Pak-Leung Ho

Queen Mary Hospital, Hong Kong, Hong Kong

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Publications (94)366.37 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: This study investigated 248 extended-spectrum β-lactamase-producing Escherichia coli isolates from 2012 to 2013 for hybrid blaCTX-M genes. blaCTX-M genes were detected in 228 isolates of which 14 isolates were hybrid blaCTX-M positive (6 blaCTX-M-123, 6 blaCTX-M-64, and 2 blaCTX-M-132). The 14 hybrid blaCTX-M-carrying isolates (8 from chickens, 2 each from pigs and cattle, 1 each from dog and rodent) were genetically diverse. All but 2 hybrid blaCTX-M were carried on IncI1 (5 blaCTX-M-123) and IncI2 (6 blaCTX-M-64 and one blaCTX-M-132) plasmids. Our IncI1 and IncI2 plasmids had pHNAH4-1-like and pHN1122-1-like restriction fragment length polymorphism patterns, respectively. Genetic relatedness of the plasmids to pHNAH4-1 and pHN1122-1 were confirmed by complete sequencing of 3 plasmids, pCTXM123_C0996, pCTXM64_C0967, and pCTXM132_P0421. Plasmids closely related to pHNAH4-1 and pHN1122-1 and carrying different blaCTX-M alleles have been reported from multiple geographic areas in China previously. The findings highlighted the wide dissemination of hybrid blaCTX-M variants in different parts of China. Copyright © 2015. Published by Elsevier Inc.
    Diagnostic microbiology and infectious disease 02/2015; 82(2). DOI:10.1016/j.diagmicrobio.2015.02.010 · 2.57 Impact Factor
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    ABSTRACT: Antimicrobial-resistant bacteria are either highly prevalent or increasing rapidly in Hong Kong and China. Treatment options for these bacteria are generally limited, less effective and more expensive. The emergence and dynamics of antimicrobial resistance genes in bacteria circulating between animals, the environment and humans are not entirely known. Nonetheless, selective pressure by antibiotics on the microbiomes of animal and human, and their associated environments (especially farms and healthcare institutions), sewage systems and soil are likely to confer survival advantages upon bacteria with antimicrobial-resistance genes, which may be further disseminated through plasmids or transposons with integrons. Therefore, antibiotic use must be tightly regulated to eliminate such selective pressure, including the illegalization of antibiotics as growth promoters in animal feed and regulation of antibiotic use in veterinary practice and human medicine. Heightened awareness of infection control measures to reduce the risk of acquiring resistant bacteria is essential, especially during antimicrobial use or institutionalization in healthcare facilities. The transmission cycle must be interrupted by proper hand hygiene, environmental cleaning, avoidance of undercooked or raw food and compliance with infection control measures by healthcare workers, visitors and patients, especially during treatment with antibiotics. In addition to these routine measures, proactive microbiological screening of hospitalized patients with risk factors for carrying resistant bacteria, including history of travel to endemic countries, transfer from other hospitals, and prolonged hospitalization; directly observed hand hygiene before oral intake of drugs, food and drinks; and targeted disinfection of high-touch or mutual-touch items, such as bed rails and bed curtains, are important. Transparency of surveillance data from each institute for public scrutiny provides an incentive for controlling antimicrobial resistance in healthcare settings at an administrative level.
    02/2015; 4(2). DOI:10.1038/emi.2015.8
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    ABSTRACT: We collected nasal, axilla and groin swabs from 252 adult patients from two nephrology centers in Hong Kong. Staphylococcus lugdunensis carriage was detected in 51.6% patients(groin, 39.3%; axilla, 19.8% and nose, 17.9%). The carriage rates of methicillin-sensitive S. lugdunensis (MSSL) and methicillin-resistant S. lugdunensis (MRSL) were 46.0% and 8.3%, respectively. Independent risk factors for S. lugdunensis carriage included male sex (odds ratio [OR], 4.4), hemodialysis (OR 2.2) and aged 18–50 years (OR 2.4). The isolates belonged to ten pulsotype clusters (n = 129) and eight singletons (n = 8). All MRSL and most gentamicin and tetracycline resistant strains were found in a predominating sequence type 3 clone, designated HKU1, which accounted for 51.8% of all colonizing S. lugdunensis strains. The 21 MRSL isolates had SCCmec type V (n = 18), type IV (n = 2) and type I (n = 1). The finding highlights the potential for dissemination of multidrug resistance through successful S. lugdunensis clones.
    Diagnostic Microbiology and Infectious Disease 11/2014; 81(2). DOI:10.1016/j.diagmicrobio.2014.10.004 · 2.57 Impact Factor
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    ABSTRACT: Secondary Streptococcus pneumoniae infection after influenza is a significant clinical complication resulting in morbidity and sometimes mortality. Prior influenza virus infection has been demonstrated to impair the macrophage and neutrophil response to the subsequent pneumococcal infection. In contrast, how the secondary pneumococcal infection after influenza can affect the adaptive immune response to the initial influenza virus infection is less well understood. Therefore, this study focuses on how secondary pneumococcal infection after influenza may impact on the humoral immune response to the initial influenza virus infection in a lethal co-infection mouse model. When compared to mice infected with influenza virus alone, mice co-infected with influenza virus followed by pneumococcus had significant body weight loss and 100% mortality. In the lung, lethal co-infection significantly increased virus titer, bacterial cell counts and decreased the level of virus specific IgG, IgM and IgA, as well as the number of B cells, CD4 T cells and plasma cells. In spleen, lethal co-infection significantly reduced the size and weight of spleen, as well as the B cells along the follicular developmental lineage. In mediastinal lymph nodes, lethal co-infection significantly decreased germinal center B cells, T follicular helper cells and plasma cells. Adoptive transfer of influenza virus-specific immune serum to co-infected mice improved survival, suggesting the protective functions of anti-influenza virus antibodies. In conclusion, co-infection reduced the B cell response to influenza virus. This study helps us to understand the modulation of B cell response to influenza virus during the lethal co-infection. Secondary pneumococcal infection after influenza is an important clinical issue that often results in excess mortality. Since antibodies are key mediator of protection, this study aims to examine the antibody response to influenza virus, and demonstrated that lethal co-infection reduced the B cell response to influenza virus. This study helps to highlight the complexity of the modulation of B cell response in the context of co-infection. Copyright © 2014, American Society for Microbiology. All Rights Reserved.
    Journal of Virology 11/2014; 89(4). DOI:10.1128/JVI.02455-14 · 4.65 Impact Factor
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    ABSTRACT: This study assessed pneumococcal carriage in the early periods after routine use of 13-valent pneumococcal conjugate vaccine (PCV13) in Hong Kong. Nasopharyngeal swabs were obtained from 1110 children (<5 years) admitted with acute illness during September 2010-August 2013. Pneumococcal carriage rate was 13.5% in unvaccinated children, 14.1% in children who had ≥1 PCV dose and 15.3% in children who had ≥3 PCV doses. Nonv-PCV13 serotypes comprised 56.4% of all isolates. The most common serogroup/types were 15 (15A, 5.1%; 15B, 10.3%; 15C, 9.6%; 15F, 0.6%), 19F (17.9%), 6A (7.1%) and 6C (7.1%). Carriage of serogroup 15 was more common among vaccinated children (4.1% versus 0.6%, P = 0.033). Molecular typing revealed that expansion of several clones (clonal complex, CC63, CC199, CC1262, CC3397) was responsible for the increase in serogroup 15. Almost all CC63 and CC3397 isolates were nonsusceptible to both penicillin and erythromycin. The finding highlights the emergence of serogroup 15 following PCV13 use.
    Diagnostic Microbiology and Infectious Disease 11/2014; 81(2). DOI:10.1016/j.diagmicrobio.2014.11.006 · 2.57 Impact Factor
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    ABSTRACT: We investigated differences in outcomes between 68 children hospitalized with macrolide-sensitive Mycoplasma pneumoniae pneumonia (MSMP group) and 25 children hospitalized with macrolide-resistant M. pneumoniae pneumonia (MRMP group). In the MRMP group, 19 children received macrolides and clinical failure occurred in six of which five had pneumonia progression during therapy. Copyright © 2014. Published by Elsevier B.V.
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    ABSTRACT: Aminoglycoside resistance determinants among 188 aminoglycoside-resistant blood culture Escherichia coli isolates from a tertiary hospital in Hong Kong, from 2004 to 2010 were investigated. Overall, 91% had aac(3)-II, 12.2% had aac(6′)-Ib/Ib-cr, and 5.4% had the methylase genes (rmtB, armA). Aminoglycoside-resistant isolates with aac(′)-Ib/Ib-cr, rmtB, and armA often had coresistance to multiple other antibiotics.
    Journal of microbiology, immunology, and infection = Wei mian yu gan ran za zhi 11/2014; DOI:10.1016/j.jmii.2014.08.012 · 2.08 Impact Factor
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    ABSTRACT: Background Prolonged asymptomatic carriage of vancomycin-resistant enterococci (VRE) in the gastrointestinal tract and the lack of effective decolonization regimen perpetuate the endemicity of VRE in the healthcare settings. Case presentation We report a regimen for decolonization of gastrointestinal carriage of VRE by a combination of environmental disinfection, patient isolation, bowel preparation to wash-out the fecal bacterial population using polyethylene glycol, a five-day course of oral absorbable linezolid and non-absorbable daptomycin to suppress any remaining VRE, and subsequent oral Lactobacillus rhamnosus GG to maintain the colonization resistance in four patients, including two patients with end-stage liver cirrhosis, one patient with complication post liver transplant, and one patient with complicated infective endocarditis. All patients had clearance of VRE immediately after decolonization, and 3 of them remained VRE-free for 23 to 137 days of hospitalization, despite subsequent use of intravenous broad-spectrum antibiotics without anti-VRE activity. Conclusion This strategy should be further studied in settings of low VRE endemicity with limited isolation facilities.
    BMC Infectious Diseases 09/2014; 14(1):514. DOI:10.1186/1471-2334-14-514 · 2.56 Impact Factor
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    ABSTRACT: Objectives We sought to document the incidence of pediatric hospitalization for bacterial pneumonia before universal childhood conjugate pneumococcal vaccination using two different methods of diagnosis. Methods By following the World Health Organization (WHO) chest radiography (CXR) protocol, two radiologists independently read the CXRs of a cohort of systematically recruited children younger than 5 years. The children had acute respiratory infections and were admitted to one of two hospitals that care for 72.5% of all pediatric admissions on Hong Kong Island. Medical records were reviewed for clinical manifestation and to identify bacterial pneumonia diagnosed by pediatricians. Results In children younger than 5 years, the incidences of bacterial pneumonia, as diagnosed by pediatricians and by the WHO CXR standard, were 775.7 per 100,000 population [95% confidence interval (CI, 591.8–998.3)] and 439.5 per 100,000 population (95% CI, 304.6–614.5), respectively. The study period was from 2002 to 2004. Conclusion This study provided a reliable baseline estimate of the hospitalization burden of pneumococcal pneumonia in Hong Kong children before the advent of universal conjugate pneumococcal vaccination.
    Journal of microbiology, immunology, and infection = Wei mian yu gan ran za zhi 07/2014; DOI:10.1016/j.jmii.2014.05.007 · 2.08 Impact Factor
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    ABSTRACT: In Escherichia coli, fosfomycin resistance is uncommon and is mainly caused by mutations in the chromosomally encoded drug transporters (1).…
    Antimicrobial Agents and Chemotherapy 06/2014; 58(9). DOI:10.1128/AAC.02700-14 · 4.45 Impact Factor
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    ABSTRACT: 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. 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 prior to receiving 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. 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. Our multifaceted assertive proactive infection control approach can minimize the nosocomial transmission and outbreak of VRE in a nonendemic area.
    Journal of the Formosan Medical Association 05/2014; 113(10). DOI:10.1016/j.jfma.2014.04.001 · 1.70 Impact Factor
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    ABSTRACT: We compared a novel selective medium (SSL) with routine method (blood and chocolate agars) for detection of Staphylococcus lugdunensis in 990 clinical specimens (tissue, pus or wound swabs). Significantly more S. lugdunensis were detected on SSL (34/990) than on routine media (7/990. McNemar test P=0.001).
    Journal of clinical microbiology 04/2014; 52(7). DOI:10.1128/JCM.00706-14 · 4.23 Impact Factor
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    ABSTRACT: Few studies have described how an expanding elderly population influences the burden of antimicrobial resistance in micro-organisms. This study aimed to investigate trends in aged-stratified extended-spectrum β-lactamases (ESBL)-positive Escherichia coli metrics in relation to an aging population. The antimicrobial resistance database of E. coli from a healthcare region in Hong Kong from 2003-2012 was retrospectively reviewed. Future trends in aged-stratified ESBL metrics were predicted up to 2022. Susceptibility results of clinical E. coli isolates from patients aged 0-74 years (n=17853) and aged ≥75 years (n=17047) were analyzed. For the period 2003-2012, 23.7% of the hospital admissions were of patients aged ≥75 years. However, approximately half of the annual ESBL-positive E. coli isolates were recovered from patients aged ≥75 years, being 55.0% (233/424) in 2003 and 56.0% (639/1142) in 2012. During this period of time, the annual prevalence and cumulative incidence of ESBL-positive E. coli in patients aged ≥75 years were significantly higher than in patients aged 0-74 years. From 2012 to 2022, it is predicted that ESBL-positive E. coli prevalence among patients aged 0-74 years and ≥75 years would increase from 25.4% to 50.2% and from 30.8% to 70.0% respectively. In 2022, the predicted ESBL-positive E. coli cumulative incidence would be 63.7 per 10,000 admissions and 178.7 per 10,000 admissions among patients aged 0-74 years and ≥75 years, respectively. In conclusion, a rapidly expanding elderly population would substantially add to the burden of ESBL.
    Journal of Medical Microbiology 04/2014; DOI:10.1099/jmm.0.068270-0 · 2.27 Impact Factor
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    ABSTRACT: To the Editor:In March 2013, a novel influenza A H7N9 virus of avian origin was reported to cause severe pneumonia in mainland China (1-3). While the great majority of patients were treated with oral oseltamivir, impaired gastrointestinal absorption in critically ill patients, the lack of virological response among patients requiring extracorporeal membrane oxygenation (ECMO) and detection of an amino acid change (arginine to lysine at residue 292 in N2) in the viral neuraminidase associated with drug resistance in two H7N9 strains are major concerns (1, 4). Here, we report a case of severe pneumonia due to avian influenza A H7N9 requiring ECMO support; there was rapid clinical and virological response following intravenous zanamivir therapy.On November 21, 2013, in Hong Kong, China, a 36-year-old Indonesian female began to have fever, malaise and cough. She had been previously healthy except for a history of vitiligo. She sought medical advice from two clinics and was given symptomatic treatment. She attended the accident and emergency department of a regional hospital in Hong Kong on November 27 when the symptoms deteriorated. Her temperature was 40.0°C, blood pressure.
    European Respiratory Journal 04/2014; 44(2). DOI:10.1183/09031936.00006414 · 7.13 Impact Factor
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    ABSTRACT: Besides seasonal and pandemic influenza (1), avian influenza viruses jumping from poultries to humans can also cause significant morbidity and mortality (2).…
    Journal of clinical microbiology 03/2014; DOI:10.1128/JCM.00446-14 · 4.23 Impact Factor
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    ABSTRACT: This study investigated the prevalence of IncX plasmid subtypes in commensal and pathogenic Escherichia coli isolates and the biological features of the IncX4 subtype. Two hundred twenty-five E. coli isolates from multiple sources (47 chicken, 41 pigs, 30 cattle and 107 humans), 2006-2012 were tested for presence of IncX1 to IncX5. Overall, the prevalence of IncX plasmids in chicken, pig, cattle and human isolates were 21.2% (10/47), 19.5% (8/41), 3.3% (1/30) and 4.8% (5/107) respectively. IncX4 was the most common subtype, followed by IncX1 and IncX3 while no IncX2 and IncX5 were found. Seven out of 16 (43.8%) IncX4 plasmids were found to carry blaCTX-M genes and six of them originating from different host sources (four chickens, one pig and one human) had identical or highly similar RFLP patterns. Three IncX4 carrying blaCTX-M plasmids from different host sources were investigated further. It was found that the IncX4 plasmids had little effect on bacterial host growth parameters after their introduction to J53 recipients. Conjugation experiments demonstrated that the IncX4 plasmids could be efficiently transferred at 30 -42oC at rates which were generally 102 to 105 folds higher than those for the epidemic IncFII plasmid carrying blaCTX-M (pHK01). In conclusion, the IncX plasmids are more common than previously recognized. The efficient transfer of IncX4 plasmid at different temperatures and lack of fitness burden on bacterial hosts highlight the ability of this plasmid replicon to be an important vehicle for dissemination of antimicrobial resistance.
    Journal of Medical Microbiology 03/2014; DOI:10.1099/jmm.0.074021-0 · 2.27 Impact Factor
  • Journal of microbiology, immunology, and infection = Wei mian yu gan ran za zhi 02/2014; DOI:10.1016/j.jmii.2013.11.010 · 2.08 Impact Factor
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    ABSTRACT: To control nosocomial transmission of methicillin-resistant Staphylococcus aureus (MRSA) in resource-limited healthcare setting with high endemicity.
    PLoS ONE 01/2014; 9(6):e100493. DOI:10.1371/journal.pone.0100493 · 3.53 Impact Factor
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    ABSTRACT: 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 prior to receiving 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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    ABSTRACT: 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. 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. 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). 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.
    Chinese medical journal 12/2013; 126(23):4504-9. · 1.02 Impact Factor

Publication Stats

2k Citations
366.37 Total Impact Points

Institutions

  • 2002–2015
    • Queen Mary Hospital
      Hong Kong, Hong Kong
  • 2014
    • Hong Kong SAR Government
      Hong Kong, Hong Kong
    • Lands Department of The Government of the Hong Kong Special Administrative Region
      Hong Kong, Hong Kong
  • 2003–2014
    • The University of Hong Kong
      • Department of Microbiology
      Hong Kong, Hong Kong
  • 2010
    • Tuen Mun Hospital
      • Department of Clinical Pathology
      Hong Kong, Hong Kong