Publications by authors named "Jonathan Hon Kwan Chen"

27 Publications

  • Page 1 of 1

Gastrointestinal colonization of methicillin-resistant Staphylococcus aureus: an unrecognized burden in the hospital infection control.

J Hosp Infect 2021 Dec 22. Epub 2021 Dec 22.

Infection Control Team, Queen Mary Hospital, Hong Kong West Cluster, Hong Kong Special Administrative Region, China; Department of Microbiology, Queen Mary Hospital, Hong Kong Special Administrative Region, China. Electronic address:

The incidence, risk factors, outcomes, and genomic relatedness of patients with newly diagnosed gastrointestinal colonization of meticillin-resistant Staphylococcus aureus (MRSA) were analyzed epidemiologically and genetically by whole genome sequencing (WGS) in a hospital network in Hong Kong. Between 1 October 2015 and 31 December 2018, 919 (2.7%) of 34,667 patients had newly diagnosed gastrointestinal MRSA colonization by admission screening. The incidence was 0.67±0.32 per 1,000-patient-days-per-quarter. Including patients with gastrointestinal MRSA colonization, the overall burden of MRSA increased by 59.2% (from 1.13±0.13 to 1.80±0.36 case per 1,000-patient-days-per-quarter), with an addition of MRSA 4,727 patient-days during the study period. Patients referred from residential care home for the elderly [odds ratio (95% confidential interval): 4.18 (3.50-4.99), p<0.001], with history of hospitalization in the past 6 months [1.90 (1.56-2.30), p<0.001], and consumption of fluoroquinolones [1.76 (1.34-2.30), p<0.001], cephalosporins [1.61 (1.11-2.31), p=0.011], and proton pump inhibitors [1.31 (1.10-1.56), p=0.002] in the preceding 6 months were found to be independent risk factors by multivariable analysis in the case-control analysis. The median survival of case was significantly shorter than control (860 vs 1507 days, p<0.001). 127 (13.8%) of 919 patients developed symptomatic MRSA infection in 112 days (median, range: 2-712 days). Of 19 patients with paired MRSA faecal and blood culture isolates subjected to WGS, clonality was found in 16 (84.2%) pairs of MRSA isolates. MRSA ST45 constituted 44.7% (17/38) of MRSA isolates. Gastrointestinal MRSA colonization may contribute to adverse clinical outcomes and pose an unrecognized burden to the hospital infection control.
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http://dx.doi.org/10.1016/j.jhin.2021.12.016DOI Listing
December 2021

Multipronged infection control strategy to achieve zero nosocomial coronavirus disease 2019 (COVID-19) cases among Hong Kong healthcare workers in the first 300 days of the pandemic.

Infect Control Hosp Epidemiol 2021 Mar 19:1-10. Epub 2021 Mar 19.

Department of Microbiology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, China.

Background: Nosocomial outbreaks leading to healthcare worker (HCW) infection and death have been increasingly reported during the coronavirus disease 2019 (COVID-19) pandemic.

Objective: We implemented a strategy to reduce nosocomial acquisition.

Methods: We summarized our experience in implementing a multipronged infection control strategy in the first 300 days (December 31, 2019, to October 25, 2020) of the COVID-19 pandemic under the governance of Hospital Authority in Hong Kong.

Results: Of 5,296 COVID-19 patients, 4,808 (90.8%) were diagnosed in the first pandemic wave (142 cases), second wave (896 cases), and third wave (3,770 cases) in Hong Kong. With the exception of 1 patient who died before admission, all COVID-19 patients were admitted to the public healthcare system for a total of 78,834 COVID-19 patient days. The median length of stay was 13 days (range, 1-128). Of 81,955 HCWs, 38 HCWs (0.05%; 2 doctors and 11 nurses and 25 nonprofessional staff) acquired COVID-19. With the exception of 5 of 38 HCWs (13.2%) infected by HCW-to-HCW transmission in the nonclinical settings, no HCW had documented transmission from COVID-19 patients in the hospitals. The incidence of COVID-19 among HCWs was significantly lower than that of our general population (0.46 per 1,000 HCWs vs 0.71 per 1,000 population; P = .008). The incidence of COVID-19 among professional staff was significantly lower than that of nonprofessional staff (0.30 vs 0.66 per 1,000 full-time equivalent; P = .022).

Conclusions: A hospital-based approach spared our healthcare service from being overloaded. With our multipronged infection control strategy, no nosocomial COVID-19 in was identified among HCWs in the first 300 days of the COVID-19 pandemic in Hong Kong.
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http://dx.doi.org/10.1017/ice.2021.119DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8060541PMC
March 2021

The use of multi-pronged screening strategy to understand the epidemiology of carbapenemase-producing Enterobacteriaceae in Hong Kong: transition from epidemic to endemic setting.

Eur J Clin Microbiol Infect Dis 2021 Sep 5;40(9):2017-2022. Epub 2021 Mar 5.

Infection Control Team, Queen Mary Hospital, Hong Kong, Hong Kong Special Administrative Region, China.

A multi-pronged carbapenemase-producing Enterobacteriaceae (CPE) screening strategy was implemented in Hong Kong West healthcare network. Of 199,192 fecal specimens from 77,194 patients screening from 1 July 2011 to 30 June 2019, the incidence of CPE per 1000 patient admission significantly increased from 0.01 (2012) to 1.9 (2018) (p<0.01). With appropriate infection control measures, the incidence of nosocomial CPE per 1000 CPE colonization day decreased from 22.34 (2014) to 10.65 (2018) (p=0.0094). Exposure to wet market for purchasing raw pork (p=0.007), beef (p=0.017), chicken (p=0.026), and vegetable (p=0.034) for >3 times per week significantly associated with community acquisition of CPE. Strategic CPE control measures should be implemented in both the hospital and the community.
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http://dx.doi.org/10.1007/s10096-021-04173-xDOI Listing
September 2021

Infection control challenges in setting up community isolation and treatment facilities for patients with coronavirus disease 2019 (COVID-19): Implementation of directly observed environmental disinfection.

Infect Control Hosp Epidemiol 2021 09 7;42(9):1037-1045. Epub 2020 Dec 7.

Infection Control Team, Queen Mary Hospital, Hong Kong West Cluster, Hong Kong Special Administrative Region, China.

Background: Extensive environmental contamination by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been reported in hospitals during the coronavirus disease 2019 (COVID-19) pandemic. We report our experience with the practice of directly observed environmental disinfection (DOED) in a community isolation facility (CIF) and a community treatment facility (CTF) in Hong Kong.

Methods: The CIF, with 250 single-room bungalows in a holiday camp, opened on July 24, 2020, to receive step-down patients from hospitals. The CTF, with 500 beds in open cubicles inside a convention hall, was activated on August 1, 2020, to admit newly diagnosed COVID-19 patients from the community. Healthcare workers (HCWs) and cleaning staff received infection control training to reinforce donning and doffing of personal protective equipment and to understand the practice of DOED, in which the cleaning staff observed patient and staff activities and then performed environmental disinfection immediately thereafter. Supervisors also observed cleaning staff to ensure the quality of work. In the CTF, air and environmental samples were collected on days 7, 14, 21, and 28 for SARS-CoV-2 detection by RT-PCR. Patient compliance with mask wearing was also recorded.

Results: Of 291 HCWs and 54 cleaning staff who managed 243 patients in the CIF and 674 patients in the CTF from July 24 to August 29, 2020, no one acquired COVID-19. All 24 air samples and 520 environmental samples collected in the patient area of the CTF were negative for SARS-CoV-2. Patient compliance with mask wearing was 100%.

Conclusion: With appropriate infection control measures, zero environmental contamination and nosocomial transmission of SARS-CoV-2 to HCWs and cleaning staff was achieved.
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http://dx.doi.org/10.1017/ice.2020.1355DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7889843PMC
September 2021

Absence of nosocomial influenza and respiratory syncytial virus infection in the coronavirus disease 2019 (COVID-19) era: Implication of universal masking in hospitals.

Infect Control Hosp Epidemiol 2021 Feb 17;42(2):218-221. Epub 2020 Aug 17.

Infection Control Team, Queen Mary Hospital, Hong Kong West Cluster, Hong Kong Special Administrative Region, China.

Universal masking for healthcare workers and patients in hospitals was adopted to combat coronavirus disease 2019 (COVID-19), with compliance rates of 100% and 75.9%, respectively. Zero rates of nosocomial influenza A, influenza B, and respiratory syncytial virus infection were achieved from February to April 2020, which was significantly lower than the corresponding months in 2017-2019.
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http://dx.doi.org/10.1017/ice.2020.425DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7468684PMC
February 2021

SARS-CoV-2 shedding and seroconversion among passengers quarantined after disembarking a cruise ship: a case series.

Lancet Infect Dis 2020 09 12;20(9):1051-1060. Epub 2020 Jun 12.

Infectious Disease Division, Department of Medicine, Queen Mary Hospital, University of Hong Kong, Hong Kong Special Administrative Region, China.

Background: A cruise ship is a closed-off environment that simulates the basic functioning of a city in terms of living conditions and interpersonal interactions. Thus, the Diamond Princess cruise ship, which was quarantined because of an onboard outbreak of COVID-19 in February, 2020, provides an opportunity to define the shedding pattern of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and patient antibody responses before and after the onset of symptoms.

Methods: We recruited adult (≥18 years) passengers from Hong Kong who had been on board the Diamond Princess cruise ship docked in Yokohama, Japan in February, 2020. All participants had been found to be negative for SARS-CoV-2 by RT-PCR 4 days before disembarking and were transferred to further quarantine in a public estate in Hong Kong, where they were recruited. Participants were prospectively screened by quantitative RT-PCR (RT-qPCR) of nasopharyngeal and throat swabs, and serum IgG and IgM against internal nucleoprotein and the surface spike receptor-binding protein (RBD) of SARS-CoV-2 at baseline (upon entering quarantine) and on days 4, 8, and 12 of quarantine.

Findings: On Feb 22, 2020, 215 adults were recruited, of whom nine (4%; 95% CI 2-8) were positive for SARS-CoV-2 by RT-qPCR or serology and were hospitalised. Of these nine patients, nasopharyngeal swab RT-qPCR was positive in eight patients (89%; 57-99) at baseline. All nine patients were positive for anti-RBD IgG by day 8. Eight (89%; 57-99) were simultaneously positive for nasopharyngeal swab RT-PCR and anti-RBD IgG. One patient who was positive for anti-RBD IgG and had a negative viral load had multifocal peripheral ground-glass changes on high-resolution CT that were typical of COVID-19. Five patients (56%; 27-81) with ground-glass changes on high-resolution CT were found to have higher anti-nucleoprotein-IgG OD values on day 8 and 12 and anti-RBD IgG OD value on day 12 than patients without ground-glass changes. Six (67%; 35-88) patients remained asymptomatic throughout the 14-day quarantine period.

Interpretation: Patients with COVID-19 can develop asymptomatic lung infection with viral shedding and those with evidence of pneumonia on imaging tend to have an increased antibody response. Positive IgG or IgM confirmed infection of COVID-19 in both symptomatic and asymptomatic patients. A combination of RT-PCR and serology should be implemented for case finding and contact tracing to facilitate early diagnosis, prompt isolation, and treatment.

Funding: Shaw Foundation Hong Kong; Sanming-Project of Medicine (Shenzhen); High Level-Hospital Program (Guangdong Health Commission).
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http://dx.doi.org/10.1016/S1473-3099(20)30364-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7292581PMC
September 2020

Evaluation of the commercially available LightMix® Modular E-gene kit using clinical and proficiency testing specimens for SARS-CoV-2 detection.

J Clin Virol 2020 08 27;129:104476. Epub 2020 May 27.

State Key Laboratory of Emerging Infectious Diseases, The University of Hong Kong, Pokfulam, Hong Kong Special Administrative Region, China; Department of Microbiology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong Special Administrative Region, China; Carol Yu Centre for Infection, The University of Hong Kong, Pokfulam, Hong Kong Special Administrative Region, China; Hainan Medical University-The University of Hong Kong Joint Laboratory of Tropical Infectious Diseases, The University of Hong Kong, Pokfulam, Hong Kong Special Administrative Region, China. Electronic address:

Background: Rapid and sensitive diagnostic assays for SARS-CoV-2 detection are required for prompt patient management and infection control. The analytical and clinical performances of LightMix® Modular SARS and Wuhan CoV E-gene kit, a widely used commercial assay for SARS-CoV-2 detection, have not been well studied.

Objective: To evaluate the performance characteristics of the LightMix® E-gene kit in comparison with well-validated in-house developed COVID-19 RT-PCR assays.

Study Design: Serial dilutions of SARS-CoV-2 culture isolate extracts were used for analytical sensitivity evaluation. A total of 289 clinical specimens from 186 patients with suspected COVID-19 and 8 proficiency testing (PT) samples were used to evaluate the diagnostic performance of the LightMix® E-gene kit against in-house developed COVID-19-RdRp/Hel and COVID-19-N RT-PCR assays.

Results: The LightMix® E-gene kit had a limit of detection of 1.8 × 10 TCID/mL, which was one log lower than those of the two in-house RT-PCR assays. The LightMix® E-gene kit (149/289 [51.6%]) had similar sensitivity as the in-house assays (144/289 [49.8%] for RdRp/Hel and 146/289 [50.5%] for N). All three assays gave correct results for all the PT samples. Cycle threshold (Cp) values of the LightMix® E-gene kit and in-house assays showed excellent correlation. Reproducibility of the Cp values was satisfactory with intra- and inter-assay coefficient of variation values <5%. Importantly, the LightMix® E-gene kit, when used as a stand-alone assay, was equally sensitive as testing algorithms using multiple COVID-19 RT-PCR assays.

Conclusions: The LightMix® E-gene kit is a rapid and sensitive assay for SARS-CoV-2 detection. It has fewer verification requirements compared to laboratory-developed tests.
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http://dx.doi.org/10.1016/j.jcv.2020.104476DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7255195PMC
August 2020

Air and environmental sampling for SARS-CoV-2 around hospitalized patients with coronavirus disease 2019 (COVID-19).

Infect Control Hosp Epidemiol 2020 11 8;41(11):1258-1265. Epub 2020 Jun 8.

Department of Microbiology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, China.

Background: The role of severe respiratory coronavirus virus 2 (SARS-CoV-2)-laden aerosols in the transmission of coronavirus disease 2019 (COVID-19) remains uncertain. Discordant findings of SARS-CoV-2 RNA in air samples were noted in early reports.

Methods: Sampling of air close to 6 asymptomatic and symptomatic COVID-19 patients with and without surgical masks was performed with sampling devices using sterile gelatin filters. Frequently touched environmental surfaces near 21 patients were swabbed before daily environmental disinfection. The correlation between the viral loads of patients' clinical samples and environmental samples was analyzed.

Results: All air samples were negative for SARS-CoV-2 RNA in the 6 patients singly isolated inside airborne infection isolation rooms (AIIRs) with 12 air changes per hour. Of 377 environmental samples near 21 patients, 19 (5.0%) were positive by reverse-transcription polymerase chain reaction (RT-PCR) assay, with a median viral load of 9.2 × 102 copies/mL (range, 1.1 × 102 to 9.4 × 104 copies/mL). The contamination rate was highest on patients' mobile phones (6 of 77, 7.8%), followed by bed rails (4 of 74, 5.4%) and toilet door handles (4 of 76, 5.3%). We detected a significant correlation between viral load ranges in clinical samples and positivity rate of environmental samples (P < .001).

Conclusion: SARS-CoV-2 RNA was not detectable by air samplers, which suggests that the airborne route is not the predominant mode of transmission of SARS-CoV-2. Wearing a surgical mask, appropriate hand hygiene, and thorough environmental disinfection are sufficient infection control measures for COVID-19 patients isolated singly in AIIRs. However, this conclusion may not apply during aerosol-generating procedures or in cohort wards with large numbers of COVID-19 patients.
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http://dx.doi.org/10.1017/ice.2020.282DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7327164PMC
November 2020

Clinical Performance of the Luminex NxTAG CoV Extended Panel for SARS-CoV-2 Detection in Nasopharyngeal Specimens from COVID-19 Patients in Hong Kong.

J Clin Microbiol 2020 Jul 23;58(8). Epub 2020 Jul 23.

Department of Microbiology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, China.

In December 2019, the coronavirus disease 2019 (COVID-19) pandemic caused by the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) was first reported in the Hubei province of China and later spread all over the world. There was an urgent need of a high-throughput molecular test for screening the COVID-19 patients in the community. The Luminex NxTAG CoV extended panel is a high-throughput FDA emergency use-authorized molecular diagnostic assay for SARS-CoV-2 detection. This system targets three genes (ORF1ab, N, and E genes) of SARS-CoV-2, the ORF1ab region of SARS-CoV, and the ORF5 region of MERS-CoV. In this study, we evaluated the diagnostic performance of this system with nasopharyngeal swab specimens of 214 suspected COVID-19 patients in Hong Kong. The results were compared with our routine COVID-19 reverse transcription-PCR (RT-PCR) protocol with a LightMix SarbecoV E-gene kit and an in-house RdRp/Hel RT-PCR assay. The NxTAG CoV extended panel demonstrated 97.8% sensitivity and 100% specificity to SARS-CoV-2 in nasopharyngeal specimens. On low-viral load specimens, the sensitivity of the NxTAG panel could still maintain at 85.71%. Strong agreement was observed between the NxTAG panel and the routine COVID-19 RT-PCR protocol (kappa value = 0.98). Overall, the E gene target of the NxTAG panel demonstrated the highest sensitivity among the three SARS-CoV-2 targets, while the N gene targets demonstrated the least. In conclusion, the NxTAG CoV extended panel is simple to use, and it has high diagnostic sensitivity and specificity to SARS-CoV-2 in nasopharyngeal specimens. We recommend this diagnostic system for high-throughput COVID-19 screening in the community.
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http://dx.doi.org/10.1128/JCM.00936-20DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7383549PMC
July 2020

Evaluating the use of posterior oropharyngeal saliva in a point-of-care assay for the detection of SARS-CoV-2.

Emerg Microbes Infect 2020 Dec;9(1):1356-1359

Department of Microbiology, Queen Mary Hospital, Pokfulam, Hong Kong Special Administrative Region, People's Republic of China.

During the Coronavirus disease 2019 (COVID-19) pandemic, logistic problems associated with specimen collection limited the SARS-CoV-2 testing, especially in the community. In this study, we assessed the use of posterior oropharyngeal saliva as specimens for the detection of SARS-CoV-2 in an automated point-of-care molecular assay. Archived nasopharyngeal swab (NPS) and posterior oropharyngeal saliva specimens of 58 COVID-19 patients were tested with the Xpert Xpress SARS-CoV-2 assay. SARS-CoV-2 was detected in either NPS or saliva specimens of all patients. Among them, 84.5% (49/58) tested positive in both NPS and saliva, 10.3% (6/58) tested positive in NPS only, and 5.2% (3/58) tested positive in saliva only. No significant difference in the detection rate was observed between NPS and saliva (McNemar's test  = 0.5078). The detection rate was slightly higher for N2 (NPS 94.8% and Saliva 93.1%) than that of the E gene target (Saliva: 89.7% vs 82.8%) on both specimen types. Significantly earlier median Ct value was observed for NPS comparing to that of saliva on both E (26.8 vs 29.7,  = 0.0002) and N2 gene target (29.3 vs 32.3,  = 0.0002). The median Ct value of E gene target was significantly earlier than that of the N2 gene target for both NPS (26.8 vs 29.3,  < 0.0001) and saliva (29.7 vs 32.3,  < 0.0001). In conclusion, posterior oropharyngeal saliva and NPS were found to have similar detection rates in the point-of-care test for SARS-CoV-2 detection. Since posterior oropharyngeal saliva can be collected easily, the use of saliva as an alternative specimen type for SARS-CoV-2 detection is recommended.
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http://dx.doi.org/10.1080/22221751.2020.1775133DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7448919PMC
December 2020

The role of community-wide wearing of face mask for control of coronavirus disease 2019 (COVID-19) epidemic due to SARS-CoV-2.

J Infect 2020 07 23;81(1):107-114. Epub 2020 Apr 23.

Department of Microbiology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, China. Electronic address:

Background: Face mask usage by the healthy population in the community to reduce risk of transmission of respiratory viruses remains controversial. We assessed the effect of community-wide mask usage to control coronavirus disease 2019 (COVID-19) in Hong Kong Special Administrative Region (HKSAR).

Methods: Patients presenting with respiratory symptoms at outpatient clinics or hospital wards were screened for COVID-19 per protocol. Epidemiological analysis was performed for confirmed cases, especially persons acquiring COVID-19 during mask-off and mask-on settings. The incidence of COVID-19 per million population in HKSAR with community-wide masking was compared to that of non-mask-wearing countries which are comparable with HKSAR in terms of population density, healthcare system, BCG vaccination and social distancing measures but not community-wide masking. Compliance of face mask usage in the HKSAR community was monitored.

Findings: Within first 100 days (31 December 2019 to 8 April 2020), 961 COVID-19 patients were diagnosed in HKSAR. The COVID-19 incidence in HKSAR (129.0 per million population) was significantly lower (p<0.001) than that of Spain (2983.2), Italy (2250.8), Germany (1241.5), France (1151.6), U.S. (1102.8), U.K. (831.5), Singapore (259.8), and South Korea (200.5). The compliance of face mask usage by HKSAR general public was 96.6% (range: 95.7% to 97.2%). We observed 11 COVID-19 clusters in recreational 'mask-off' settings compared to only 3 in workplace 'mask-on' settings (p = 0.036 by Chi square test of goodness-of-fit).

Conclusion: Community-wide mask wearing may contribute to the control of COVID-19 by reducing the amount of emission of infected saliva and respiratory droplets from individuals with subclinical or mild COVID-19.
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http://dx.doi.org/10.1016/j.jinf.2020.04.024DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7177146PMC
July 2020

High index of suspicion for brucellosis in a highly cosmopolitan city in southern China.

BMC Infect Dis 2020 Jan 8;20(1):22. Epub 2020 Jan 8.

Department of Clinical Microbiology and Infection Control, The University of Hong Kong - Shenzhen Hospital, Shenzhen, China.

Background: Brucellosis is one of the most widespread zoonosis in the world. In China, 90% of human brucellosis occurs in six northern agricultural provinces. However, there is a recent increase in the trend of human brucellosis in southern provinces with limited cases reported in the literature. Our study aims to describe the clinical features and epidemiology of brucellosis in a tertiary hospital in southern China.

Methods: A retrospective case series of brucellosis was conducted between January 1, 2014 and October 31. 2018. Cases were identified based on positive Brucella serology by tube agglutination test, or positive culture from clinical specimen identified by Vitek 2 and MALDL-TOF MS. Clinical details of brucellosis including patients' occupation, risk factors, and complications were analyzed. Clinical characteristics between patients from Guangdong and other provinces were also compared.

Results: A total of 13 cases of laboratory-confirmed brucellosis were identified. 7 (53.8%) of the patients were male, 6 (46.2%) were female, with age ranging from 29 to 73 years old (median age: 51 years). 5 patients (38.5%) were from Guangdong province, while the remaining patients (61.5%) were from other provinces. The commonest risk factors of acquisition were consumption of undercooked meat and goat placenta. Patients from Guangdong province were found to be more likely to have prior placenta consumption. The commonest clinical presentations were fever, osteoarticular pain, urinary symptoms, splenomegaly, and lymphadenopathy. Spondylodiscitis/ peripheral joint arthritis (5 patients, 38.5%) was the most prevalent complication, while extra-osteoarticular complications including abdominal aortitis, hepatosplenic abscess, chest wall abscess, and epididymo-orchitis were observed in 4 other patients. Furthermore, it was demonstrated that MALDI-TOF MS is reliable in Brucella identification after additional of reference spectra with standard Brucella strain.

Conclusions: Brucellosis, previously thought to be only found in northern China, is now increasingly seen in highly cosmopolitan part of southern China. MALDI-TOF MS in hospitals in China should include reference spectra with standard Brucella strain to aid bacterial identification in routine clinical practice. In addition to tuberculosis, typhoid fever and typhus, brucellosis should be considered in patients with fever of unknown origin in this locality.
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http://dx.doi.org/10.1186/s12879-019-4748-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6950854PMC
January 2020

Molecular Characterization of HIV-1 Minority Subtypes in Hong Kong: A Recent Epidemic of CRF07_BC among the Men who have Sex with Men Population.

Curr HIV Res 2019 ;17(1):53-64

Department of Microbiology, Queen Mary Hospital, The University of Hong Kong, Hong Kong.

Background: Over the past years, an increasing trend was noticed for non-B and non- CRF01_AE HIV-1 strains prevalence in Hong Kong.

Objective: In this study, we aimed at using the available HIV-1 pol sequences collected from 1994 to 2013 through our local antiretroviral resistance surveillance program to investigate the molecular epidemiology and evolution of HIV-1 minority subtypes in Hong Kong. We also aimed at investigating their potential association and impact of those transmission risk groups.

Methods: A total of 2,315 HIV-1 partial pol sequences were included. HIV-1 genotypes were determined by REGA Genotyping Tool and phylogenetic analysis with reference sequences. The viral evolutionary rates and time of the most common ancestor (tMRCA) were estimated by Bayesian Markov Chain Monte Carlo (MCMC) interference.

Results: Apart from the two prevalent HIV-1 genotypes in Hong Kong (subtype B,41.6%, CRF01_AE,40.5%), phylogenetic analysis revealed a broad viral diversity including CRF07_BC(5.1%), subtype C(4.5%), CRF02_AG(1.1%), CRF08_BC(0.8%), subtype A1(0.8%), subtype G(0.4%), subtype D(0.4%), CRF06_cpx(0.4%), subtype F(0.1%), CRF12_BF(0·04%) and other recombinants(4.5%). The top five minority subtypes were further analyzed which demonstrated distinct epidemiological and phylogenetic patterns. Over 70% of subtypes A1, C and CRF02_AG infections were circulated among non-Chinese Asians or African community in Hong Kong and were mainly transmitted between heterosexual regular partners. Instead, over 90% of CRF07_BC and CRF08_BC patients were Chinese. An epidemic cluster was identified in CRF07_BC and estimated to expand from 2002 onwards based on skyline plot and molecular clock analysis.

Conclusion: Our results highlighted the emergence of CRF07_BC epidemic in local MSM community, public health interventions targeting the community should be further enhanced to tackle the epidemic.
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http://dx.doi.org/10.2174/1570162X17666190530081355DOI Listing
February 2020

Emergence of carbapenem-resistant hypervirulent Klebsiella pneumoniae.

Lancet Infect Dis 2018 01 1;18(1):24. Epub 2017 Nov 1.

Shenzhen Key lab for Food Biological Safety Control, Food Safety and Technology Research Center, Hong Kong PolyU Shen Zhen Research Institute, Shenzhen, China; State Key Lab of Chirosciences, Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hong Kong Special Administrative Region, China. Electronic address:

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http://dx.doi.org/10.1016/S1473-3099(17)30629-1DOI Listing
January 2018

Development and in-use evaluation of a novel Luminex MicroPlex microsphere-based (TRIOL) assay for simultaneous identification of and detection of first-line and second-line anti-tuberculous drug resistance in China.

J Clin Pathol 2017 Apr 19;70(4):342-349. Epub 2016 Sep 19.

State Key Laboratory of Emerging Infectious Diseases, The University of Hong Kong, Hong Kong Special Administrative Region, Hong Kong, China.

Aims: Rapid and accurate diagnostic assays with simultaneous microbial identification and drug resistance detection are essential for optimising treatment and control of tuberculosis.

Methods: We developed a novel multiplex (TRIOL, Tuberculosis-Rifampicin-Isoniazid-Ofloxacin-Luminex) assay using the Luminex xMAP system that simultaneously identifies and detects resistance to first-line and second-line anti-tuberculous drugs, and compared its performance with that by PCR sequencing, using phenotypic drug susceptibility testing as the gold standard.

Results: Identification of by the TRIOL assay was highly sensitive (100%) and specific (100%). The overall drug-specific specificities were excellent (100%). The overall sensitivity of the TRIOL assay was lower than that of the PCR-sequencing assays (72.4% vs 82.8%) because of a lower sensitivity of detecting rifampicin resistance (71.4% vs 92.9%). The sensitivity of detecting isoniazid and ofloxacin resistance was as good as the PCR-sequencing assays. Importantly, the TRIOL assay did not miss any mutations that were included in the assay. All of the resistant isolates that were missed had uncommon mutations or unknown resistance mechanisms that were not included in the assay.

Conclusions: The TRIOL assay has higher throughput, lower cost and is less labour intensive than the PCR-sequencing assays. The TRIOL assay is advantageous in having the capability to detect resistance to multiple drugs and an open-architecture system that allows addition of more specific primers to detect uncommon mutations. Inclusion of additional primers for the identification of non-tuberculous mycobacteria, spoligotyping and improvement of rifampicin resistance detection would enhance the use of the TRIOL assay in future clinical and epidemiological studies.
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http://dx.doi.org/10.1136/jclinpath-2016-203952DOI Listing
April 2017

Clinical Characteristics, Laboratory Identification, and In Vitro Antifungal Susceptibility of Yarrowia (Candida) lipolytica Isolates Causing Fungemia: a Multicenter, Prospective Surveillance Study.

J Clin Microbiol 2015 Nov 26;53(11):3639-45. Epub 2015 Aug 26.

State Key Laboratory of Emerging Infectious Diseases, The University of Hong Kong, Hong Kong Department of Microbiology, The University of Hong Kong, Hong Kong Research Centre of Infection and Immunology, The University of Hong Kong, Hong Kong Carol Yu Centre for Infection, The University of Hong Kong, Hong Kong

Our case series showed that uncomplicated Yarrowia lipolytica fungemia might be treated with catheter removal alone. The Vitek 2 YST identification (ID) card system, matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS), and internal transcribed spacer and 25S nuclear ribosomal DNA (nrDNA) gene sequencing provided reliable identification. All isolates had low MICs to voriconazole, echinocandins, and amphotericin B.
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http://dx.doi.org/10.1128/JCM.01985-15DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4609733PMC
November 2015

Minimal intervention for controlling nosocomial transmission of methicillin-resistant staphylococcus aureus in resource limited setting with high endemicity.

PLoS One 2014 19;9(6):e100493. Epub 2014 Jun 19.

Department of Microbiology, Queen Mary Hospital, Hong Kong Special Administrative Region, China; Carol Yu Centre for Infection, The University of Hong Kong, Hong Kong Special Administrative Region, China.

Objective: To control nosocomial transmission of methicillin-resistant Staphylococcus aureus (MRSA) in resource-limited healthcare setting with high endemicity.

Methods: Three phases of infection control interventions were implemented in a University-affiliated hospital between 1-January-2004 and 31-December-2012. The first phase of baseline period, defined as the first 48-months of the study period, when all MRSA patients were managed with standard precautions, followed by a second phase of 24-months, when a hospital-wide hand hygiene campaign was launched. In the third phase of 36-months, contact precautions in open cubicle, use of dedicated medical items, and 2% chlorhexidine gluconate daily bathing for MRSA-positive patients were implemented while hand hygiene campaign was continued. The changes in the incidence rates of hospital-acquired MRSA-per-1000-patient admissions, per-1000-patient-days, and per-1000-MRSA-positive-days were analyzed using segmented Poisson regression (an interrupted time series model). Usage density of broad-spectrum antibiotics was monitored.

Results: During the study period, 4256 MRSA-positive patients were newly diagnosed, of which 1589 (37.3%) were hospital-acquired. The reduction of hospital-acquired MRSA per 1000-patient admissions, per 1000-patient-days, and per 1000-MRSA-positive-days from phase 1 to 2 was 36.3% (p<0.001), 30.4% (p<0.001), and 19.6% (p = 0.040), while the reduction of hospital-acquired MRSA per 1000-patient admissions, per 1000-patient-days, and per 1000-MRSA-positive-days from phase 2 to 3 was 27.4% (p<0.001), 24.1% (p<0.001), and 21.9% (p = 0.041) respectively. This reduction is sustained despite that the usage density of broad-spectrum antibiotics has increased from 132.02 (phase 1) to 168.99 per 1000 patient-days (phase 3).

Conclusions: Nosocomial transmission of MRSA can be reduced with hand hygiene campaign, contact precautions in open cubicle, and 2% chlorhexidine gluconate daily bathing for MRSA-positive despite an increasing consumption of broad-spectrum antibiotics.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0100493PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4063951PMC
March 2015

HIV-1 transmission networks among men who have sex with men in Asia.

Clin Infect Dis 2014 Sep 18;59(6):910-1. Epub 2014 Jun 18.

Centre of Excellence for Research in AIDS (CERiA), Department of Medicine, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia.

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http://dx.doi.org/10.1093/cid/ciu480DOI Listing
September 2014

Proactive infection control measures to prevent nosocomial transmission of vancomycin-resistant enterococci in Hong Kong.

J Formos Med Assoc 2014 Oct 3;113(10):734-41. Epub 2014 May 3.

Department of Microbiology, Queen Mary Hospital, Hong Kong Special Administrative Region, China; Carol Yu Centre for Infection, The University of Hong Kong, Hong Kong Special Administrative Region, China. Electronic address:

Background/purpose: The study describes a proactive infection control approach to prevent nosocomial transmission of vancomycin-resistant enterococci (VRE) and tests if this approach is effective for controlling multiple-drug resistant organisms in a nonendemic setting.

Methods: In response to the increasing prevalence of VRE in Hong Kong since 2011, we adopted a multifaceted assertive approach in our health care network. This included active surveillance culture, extensive contact tracing, directly observed hand hygiene in conscious patients before they received meals and medications, stringent hand hygiene and environmental cleanliness, and an immediate feedback antimicrobial stewardship program. We report the occurrence of VRE outbreaks in our hospital after institution of these measures and compared with the concurrent occurrence in other public hospitals in Hong Kong.

Results: Between July 1, 2011 and November 13, 2013, VRE was identified in 0.32% (50/15,851) of admission episodes by active surveillance culture. The risk of VRE carriage was three times higher in patients with a history of hospitalization outside our hospital networks in the past 3 months (0.56% vs. 0.17%; p = 0.001) compared with those who were not. Extensive contact tracing involving 3277 patient episodes was performed in the investigation for the 25 VRE index patients upon whom implementation of contact precautions was delayed (more than 48 hours of hospitalization). One episode of VRE outbreak was identified in our hospital network, compared with the 77 VRE outbreaks reported in the other hospital networks (controls) without these proactive infection control measures.

Conclusion: Our multifaceted assertive proactive infection control approach can minimize the nosocomial transmission and outbreak of VRE in a nonendemic area.
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http://dx.doi.org/10.1016/j.jfma.2014.04.001DOI Listing
October 2014

Proactive infection control measures to prevent nosocomial transmission of carbapenem-resistant Enterobacteriaceae in a non-endemic area.

Chin Med J (Engl) 2013 Dec;126(23):4504-9

Department of Microbiology, Queen Mary Hospital, Hong Kong, China; Infection Control Team, Queen Mary Hospital, Hong Kong, China.

Background: Identification of hospitalized carbapenem-resistant Enterobacteriaceae (CRE)-positive patient is important in preventing nosocomial transmission. The objective of this study was to illustrate the implementation of proactive infection control measures in preventing nosocomial transmission of CRE in a healthcare region of over 3200 beds in Hong Kong between October 1, 2010 and December 31, 2011.

Methods: The program included active surveillance culture in patients with history of medical tourism with hospitalization and surgical operation outside Hong Kong within 12 months before admission, and "added test" as an opportunistic CRE screening in all fecal specimens submitted to the laboratory. Outbreak investigation and contact tracing were conducted for CRE-positive patients. Serial quantitative culture was performed on CRE-positive patients and the duration of fecal carriage of CRE was analyzed.

Results: During the study period, a total of 6533 patients were screened for CRE, of which 76 patients were positive (10 from active surveillance culture, 65 from "added test", and 1 secondary case from contact tracing of 223 patients with no nosocomial outbreak), resulting in an overall rate of CRE fecal carriage of 1.2%. The median time of fecal carriage of CRE was 43 days (range, 13-119 days). Beta-lactam-beta-lactamase-inhibitors, cephalosporins, and fluoroquinolones were associated significantly with high fecal bacterial load when used 90 days before CRE detection, while use of cephalosporins, carbapenems, and fluoroquinolones after CRE detection are significantly associated with longer duration of carriage. The duration of fecal carriage of CRE also correlates significantly with the initial fecal bacterial load (Pearson correlation: 0.53; P = 0.02).

Conclusion: Proactive infection control measures by enhanced surveillance program identify CRE-positive patients and data obtained are useful for the planning of and resource allocation for CRE control.
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December 2013

Performance comparison of an in-house integrase genotyping assay versus the ViroSeq™ Integra48, and study of HIV-1 integrase polymorphisms in Hong Kong.

J Clin Virol 2013 Sep 22;58(1):299-302. Epub 2013 Jul 22.

Department of Microbiology, Queen Mary Hospital, The University of Hong Kong, Hong Kong Special Administrative Region.

Background: Integrase inhibitors are recently prescribed to multi-class drug resistant HIV-1 patients in Hong Kong. Unlike pol gene, there are no FDA-approved genotypic resistance tests available for int. Limited studies compared the performance between an in-house and commercial integrase genotyping system. Information on baseline polymorphisms was also insufficient in our region.

Objectives: To compare integrase genotyping data obtained from an in-house and ViroSeq™ Integra48 assay, and to illustrate integrase polymorphisms on HIV-1 B and non-B subtypes in Hong Kong.

Study Design: A total of 283 HIV-1 patients were recruited during 2006-2012 in Hong Kong. All samples were genotyped by an in-house assay for pol and int separately, and 46 of them were further genotyped by ViroSeq™ Integra48. Polymorphisms and resistance mutations were analyzed by Stanford HIV Drug Resistance Database.

Results: The included patients were mainly infected by HIV-1 subtype B (38.9%) and CRF01_AE (43.1%), followed by CRF07_BC (5.3%), C (3.9%), CRF02_AG (2.8%), D (1.4%), CRF08_BC (1.1%) or others (3.5%). Of 46 samples genotyped by ViroSeq™ and the in-house assays, all major and minor resistance mutations were concordant. Integrase major resistance mutations were identified in two CRF01_AE raltegravir-treated patients. Integrase minor resistance mutations were observed in subtypes B and CRF01_AE.

Conclusions: With 25% of the commercial cost, the in-house integrase genotyping assay managed to regenerate over 96% concordant results as good as the RUO ViroSeq™ assay. Further investigations are required to understand the effect on integrase minor mutations, which are present in many subtype B and CRF01_AE samples.
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http://dx.doi.org/10.1016/j.jcv.2013.06.040DOI Listing
September 2013

Determination of the high prevalence of Dual/Mixed- or X4-tropism among HIV type 1 CRF01_AE in Hong Kong by genotyping and phenotyping methods.

AIDS Res Hum Retroviruses 2013 Aug 31;29(8):1123-8. Epub 2013 May 31.

Department of Microbiology, Queen Mary Hospital, the University of Hong Kong, Hong Kong Special Administrative Region, China.

In Hong Kong, the CCR5 antagonist has recently been introduced into salvage therapy for multiclass drug-resistant HIV-1-infected patients. Coreceptor usage must be determined prior to the usage of the CCR5 antagonist, which does not inhibit X4-tropic viruses. This study aimed to determine the tropism prevalence for HIV-1 subtypes B and CRF01_AE in Hong Kong. In addition, a modified promoter-PCR phenotypic assay was used to validate the genotypic tropism prediction on CRF01_AE. One hundred and five subtype B and 98 CRF01_AE antiretroviral-naive patients were recruited for this study. The viral env V3 region isolated from the patients was sequenced and analyzed by Geno2pheno (FPR=5.75% or 10%, Clonal or Clinical), position-specific scoring matrix (WebPSSM, x4r5 subtype B matrix), and the combination of 11/25 and net charge rules. Fifteen concordant and 22 discordant tropism genotyped CRF01_AE samples were further phenotyped by either enhanced sensitivity Trofile assay or an optimized promoter-PCR phenotypic assay. The prevalence of Dual/Mixed- or X4-tropic virus in antiretroviral-naive subtype CRF01_AE was 39.1%, which was significantly higher than subtype B (p<0.05), regardless of the choices of genotypic algorithms. Our phenotypic data proposed that a better genotypic tropism prediction for HIV-1 CRF01_AE would be using both Geno2pheno (FPR=10%, Clonal) and WebPSSM (x4r5 subtype B matrix) algorithms in combination. The sensitivity and specificity for this combination were 88.9% and 89.3%, respectively. The comparatively high prevalence of Dual/Mixed- or X4-tropic virus in CRF01_AE demonstrated the need for special attention to future treatment strategies.
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http://dx.doi.org/10.1089/aid.2013.0067DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3715771PMC
August 2013

An unprecedented outbreak investigation for nosocomial and community-acquired legionellosis in Hong Kong.

Chin Med J (Engl) 2012 Dec;125(23):4283-90

Department of Microbiology, Queen Mary Hospital, Hong Kong, China.

Background: The environmental sources associated with community-acquired or nosocomial legionellosis were not always detectable in the mainland of China and Hong Kong, China. The objective of this study was to illustrate the control measures implemented for nosocomial and community outbreaks of legionellosis, and to understand the environmental distribution of legionella in the water system in Hong Kong, China.

Methods: We investigated the environmental sources of two cases of legionellosis acquired in the hospital and the community by extensive outbreak investigation and sampling of the potable water system using culture and genetic testing at the respective premises.

Results: The diagnosis of nosocomial legionellosis was suspected in a patient presenting with nosocomial pneumonia not responsive to multiple beta-lactam antibiotics with subsequent confirmation by Legionella pneumophila serogroup 1 antigenuria. High counts of Legionella pneumophila were detected in the potable water supply of the 70-year-old hospital building. Another patient on continuous ambulatory peritoneal dialysis presenting with acute community-acquired pneumonia and severe diarrhoea was positive for Legionella pneumophila serogroup 1 by polymerase chain reaction (PCR) testing on both sputum and nasopharyngeal aspirate despite negative antigenuria. Paradoxically the source of the second case was traced to the water system of a newly commissioned office building complex. No further cases were detected after shock hyperchlorination with or without superheating of the water systems. Subsequent legionella counts were drastically reduced. Point-of-care infection control by off-boiled or sterile water for mouth care and installation of water filter for showers in the hospital wards for immunocompromised patients was instituted. Territory wide investigation of the community potable water supply showed that 22.1% of the household water supply was positive at a mean legionella count of 108.56 CFU/ml (range 0.10 to 639.30 CFU/ml).

Conclusions: Potable water systems are open systems which are inevitably colonized by bacterial biofilms containing Legionella species. High bacterial counts related to human cases may occur with stagnation of flow in both old or newly commissioned buildings. Vigilance against legionellosis is important in healthcare settings with dense population of highly susceptible hosts.
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December 2012

The use of high-resolution melting analysis for rapid spa typing on methicillin-resistant Staphylococcus aureus clinical isolates.

J Microbiol Methods 2013 Feb 13;92(2):99-102. Epub 2012 Nov 13.

Department of Microbiology, Queen Mary Hospital, Hong Kong Special Administrative Region, China.

Methicillin-resistant Staphylococcus aureus (MRSA) has been endemic in Hong Kong for three decades. This study evaluated the practical use of high-resolution melting (HRM) real-time PCR analysis on MRSA staphylococcal Protein A (spa) typing on local MRSA isolates. Among 55 clinical MRSA isolates collected in 2011, 12 different spa types were observed by the conventional PCR-sequencing method including the locally predominant spa type t1081 and two locally predominant community acquired MRSA spa types t019 and t437. By using the HRM method, it could differentiate all 12 spa genotypes by distinct melting curves and HRM difference plot analysis. These two methods demonstrated 100% concordance whereas the HRM method required only 3h of turnaround time and one-fifth of reagent cost compared to the conventional method. Our study confirmed that the cost effective and rapid HRM typing approach is practically useful for MRSA community transmission monitoring and nosocomial outbreak control in Hong Kong.
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http://dx.doi.org/10.1016/j.mimet.2012.11.006DOI Listing
February 2013

Phylodynamics of HIV-1 subtype B among the men-having-sex-with-men (MSM) population in Hong Kong.

PLoS One 2011 22;6(9):e25286. Epub 2011 Sep 22.

Department of Microbiology, Queen Mary Hospital, the University of Hong Kong, Hong Kong Special Administrative Region, China.

The men-having-sex-with-men (MSM) population has become one of the major risk groups for HIV-1 infection in the Asia Pacific countries. Hong Kong is located in the centre of Asia and the transmission history of HIV-1 subtype B transmission among MSM remained unclear. The aim of this study was to investigate the transmission dynamics of HIV-1 subtype B virus in the Hong Kong MSM population. Samples of 125 HIV-1 subtype B infected MSM patients were recruited in this study. Through this study, the subtype B epidemic in the Hong Kong MSM population was identified spreading mainly among local Chinese who caught infection locally. On the other hand, HIV-1 subtype B infected Caucasian MSM caught infection mainly outside Hong Kong. The Bayesian phylogenetic analysis also indicated that 3 separate subtype B epidemics with divergence dates in the 1990s had occurred. The first and latest epidemics were comparatively small-scaled; spreading among the local Chinese MSM while sauna-visiting was found to be the major sex partner sourcing reservoir for the first subtype B epidemic. However, the second epidemic was spread in a large-scale among local Chinese MSM with a number of them having sourced their sex partners through the internet. The epidemic virus was estimated to have a divergence date in 1987 and the infected population in Hong Kong had a logistic growth throughout the past 20 years. Our study elucidated the evolutionary and demographic history of HIV-1 subtype B virus in Hong Kong MSM population. The understanding of transmission and growth model of the subtype B epidemic provides more information on the HIV-1 transmission among MSM population in other Asia Pacific high-income countries.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0025286PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3178636PMC
February 2012

Increased genetic diversity of HIV-1 circulating in Hong Kong.

PLoS One 2010 Aug 16;5(8):e12198. Epub 2010 Aug 16.

Department of Microbiology, Queen Mary Hospital, The University of Hong Kong, Hong Kong, Special Administrative Region, China.

HIV-1 group M strains are characterized into 9 pure subtypes and 48 circulating recombinant forms (CRFs). Recent studies have identified the presence of new HIV-1 recombinants in Hong Kong and their complexity continues to increase. This study aims to characterize the HIV-1 genetic diversity in Hong Kong. Phylogenetic analyses were performed by using HIV-1 pol sequences including protease and partial reverse transcriptase isolated from 1045 local patients in Hong Kong from 2003 to 2008. For the pol sequences with unassigned genotype, the evidence of recombination was determined by using sliding-window based bootscan plots and their env C2V3 region were also sequenced. Epidemiological background of these patients was further collected. The pol phylogenetic analyses highlighted the extent of HIV-1 genetic diversity in Hong Kong. Subtype B (450/1045; 43.1%) and CRF01_AE (469/1045; 44.9%) variants were clearly predominant. Other genotypes (126/1045; 12.1%) including 3 defined subtypes, 10 CRFs, 1 unassigned subtype and 33 recombinants with 11 different mosaic patterns were observed. Recombinants of subtype B and CRF01_AE were mainly found among local Chinese MSM throughout 2004 to 2008, while the CRF02_AG and subtype G recombinants were circulating among non-Chinese Asian population in Hong Kong through heterosexual transmission starting from 2008. Our study demonstrated the complex recombination of HIV-1 in Hong Kong and the need in developing surveillance system for tracking the distribution of new HIV-1 genetic variants.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0012198PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2922374PMC
August 2010
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