Tak-Lun Que

Tuen Mun Hospital, Hong Kong, Hong Kong

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Publications (35)146.2 Total impact

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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; · 4.16 Impact Factor
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    ABSTRACT: Human infections caused by avian influenza virus A(H7N9) re-emerged in late 2013. We reported the first Hong Kong patient without risk factors for severe A(H7N9) disease. Direct sequencing was performed on the endotracheal aspirate collected from a 36-year-old female with history of poultry contact. Bioinformatic analysis was performed to compare the current strain and previous A(H7N9) isolates. The influenza A/Hong Kong/470129/2013 virus strain was detected in a patient with acute respiratory distress syndrome, deranged liver function and coagulation profile, cytopenia, and rhabdomyolysis, The HA, NA and MP genes of A/Hong Kong/470129/2013 cluster with those of other human A(H7N9) strains. The PB1, PB2 and NS genes are most closely related to those of A/Guangdong/1/2013 strain identified in August 2013, but are distinct from those of other human and avian A(H7N9) strains. The other internal genes NP and PA genes are more closely related to those of non-A(H7N9) avian influenza A viruses. A unique PA L336M mutation, associated with increased polymerase activity, was found. The patient required salvage by extracorporeal membrane oxygenation. The A/Hong Kong/470129/2013 virus is a novel reassortant derived from A/Guangdong/1/2013 virus. The unique mutation PA L336M may enhance viral replication and therefore disease severity.
    The Journal of infection 02/2014; · 4.13 Impact Factor
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    ABSTRACT: The IncA/C plasmids are broad host-range vehicles which have been associated with wide dissemination of CMY-2 among Enterobacteriaceae of human and animal origins. Acquired metallo-β-lactamases (MBLs) such as the IMP-type enzymes are increasingly reported in multidrug-resistant Gram-negative bacteria worldwide, particularly in Enterobacteriaceae. We described the complete sequence of the first IMP-4-encoding IncA/C2 plasmid, pIMP-PH114 (151,885 bp), from a sequence type 1 Klebsiella pneumoniae strain that was recovered from a patient who was hospitalized in the Philippines. pIMP-PH114 consists of a backbone from the IncA/C2 plasmids, with the insertion of a novel Tn21-like class 1 integron composite structure (containing the cassette array bla IMP-4-qacG-aacA4-catB3, followed by a class C β-lactamase bla DHA-1 and the mercury resistance operon, merRTPCADE) and a sul2-floR encoding region. Phylogenetic analysis of the IncA/C repA sequences showed that pIMP-PH114 formed a subgroup with other IncA/C plasmids involved in the international spread of CMY-2, TEM-24 and NDM-1. Identical bla IMP-4 arrays have been described among different Enterobacteriaceae and Acinetobacter spp. in China, Singapore and Australia but the genetic context is different. The broad host range of IncA/C plasmids may have facilitated dissemination of the bla IMP-4 arrays among different diverse groups of bacteria.
    Current Microbiology 10/2013; · 1.52 Impact Factor
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    ABSTRACT: In China, IMP-4 is a major plasmid-mediated carbapenemase among multidrug-resistant Enterobacteriaceae but little is known about the plasmid scaffolds involved in the dissemination of bla(IMP-4) (1,2).…
    Antimicrobial Agents and Chemotherapy 12/2012; · 4.57 Impact Factor
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    ABSTRACT: The New Delhi metallo-β-lactamase (NDM-1) is one of the most important resistance traits in Enterobacteriaceae. We characterized nine blaNDM-1 producing Enterobacteriaceae recovered from seven patients who have recently travelled or been treated in India (n=1) or mainland China (n=6) during December 2010–May 2012. All the China-linked patients had no links to the Indian subcontinent. The blaNDM-1 carrying plasmids belonged to the novel IncX3 (~50 kb, in seven isolates including two Escherichia coli, two Klebsiella pneumoniae, one Citrobacter freundii, one Enterobacter aerogenes and one E. cloacae), IncA/C2 (~140 kb, in one E. coli) or FII-F1B groups (~110 kb, in one E. coli). Restriction fragment length polymorphism analysis of the seven IncX3 plasmids revealed identical pattern in six and two bands difference in the remaining one. The IncX3 plasmids carrying blaNDM-1 were epidemiologically linked to Guangzhou (n=1), Hunan (n=4), Haifeng (n=1) and Dongguan (n=1) in mainland China. Complete sequencing of the IncX3 plasmid pNDM-HN380 revealed that it was 54 035 bp long and encoded 52 open reading frames. The blaNDM-1 gene was found in a transposon-like structure flanked by ISAba125 and IS26, inserted into the plasmid genetic load region. The sequences of the blaNDM-1 containing module within the two IS elements were identical to those previously described for blaNDM-1-positive Tn125 in the plasmids or chromosome of Acinetobacter isolates. In summary, this is the first description of IncX3 plasmids carrying blaNDM-1. The findings indicate the worrisome involvement of an epidemic plasmid in the dissemination of NDM-1 in China.
    Emerging Microbes & Infections. 11/2012; 1(11).
  • International journal of antimicrobial agents 10/2012; · 3.03 Impact Factor
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    ABSTRACT: Catabacter hongkongensis is a recently described catalase-positive, motile, anaerobic, nonsporulating, Gram-positive coccobacillus that was first isolated from blood cultures of four patients from Hong Kong and Canada. Although DNA sequences representing C. hongkongensis have been detected in environmental sources, only one additional case of human infection has been reported, in France. We describe five cases of C. hongkongensis bacteremia in Hong Kong, two presenting with sepsis, one with acute gangrenous perforated appendicitis, one with acute calculous cholecystitis, and one with infected carcinoma of colon. Three patients, with gastrointestinal malignancy, died during admission. All five isolates were catalase positive, motile, and negative for indole production and nitrate reduction and produced acid from arabinose, glucose, mannose, and xylose. They were unambiguously identified as C. hongkongensis by 16S rRNA gene analysis. Of the total of 10 reported cases of C. hongkongensis bacteremia in the literature and this study, most patients had underlying diseases, while two cases occurred in healthy young individuals with acute appendicitis. Six patients presented with infections associated with either the gastrointestinal or biliary tract, supporting the gastrointestinal tract as the source of bacteremia. C. hongkongensis bacteremia is associated with a poor prognosis, with a high mortality of 50% among reported cases, especially in patients with advanced malignancies. All reported isolates were susceptible to metronidazole. Identification of more C. hongkongensis isolates by 16S rRNA gene sequencing will help better define its epidemiology and pathogenesis.
    Journal of clinical microbiology 04/2012; 50(7):2239-43. · 4.16 Impact Factor
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    ABSTRACT: Despite recent discovery of the novel human rhinovirus species, HRV-C, little is known about the association of HRV-C in diseases other than respiratory tract infections. To investigate the presence of HRV-C in fecal samples of children with gastroenteritis. 734 fecal samples from hospitalized children with gastroenteritis were subject to picornavirus detection by RT-PCR of the conserved 5'-NCR. Positive samples were subject to VP4 and 3D(pol) gene analysis for species determination. The clinical and molecular epidemiology of HRV-C and other picornaviruses was analyzed. Picornaviruses were detected in 113 (15.4%) of 734 fecal samples from children with gastroenteritis by RT-PCR of 5'-NCR, with 58 containing potential HRVs and 55 containing other enteroviruses. PCR of the VP4 and 3D(pol) regions was positive in 21 and 19 samples respectively (both regions positive in 8 samples). Sequencing analysis showed the presence of HRV-C in four samples, and diverse picornaviruses including HRV-A (n=2), HEV-A (n=2), HEV-B (n=2), HEV-C (n=21) and HPeV (n=2) in other samples, with co-detection of HRV-C and HPeV in one sample. Of the four children with HRV-C detected in fecal samples, three presented with diarrhea in the absence of respiratory symptoms, while one also had acute bronchiolitis. The four HRV-C strains from fecal samples belonged to the existing clade of diverse HRV-C genotypes, indistinguishable from previous respiratory strains. HRV-C can be detected in fecal samples of children with gastroenteritis, in the absence of respiratory symptoms. This study also represented the first to detect HPeV in our population.
    Journal of clinical virology: the official publication of the Pan American Society for Clinical Virology 02/2012; 53(4):290-6. · 3.12 Impact Factor
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    ABSTRACT: Influenza-associated encephalopathy (IAE) is a potentially fatal neurological complication of influenza infection usually in the presence of high and persistent fever. Thermolabile carnitine palmitoyltransferase II enzyme (CPT-II) predisposes IAE, so far only described in Japanese. As the genetic origins of Japanese and Chinese are alike, similar genetic risk factors in CPT-II are expected. We report the first two unrelated Chinese patients of thermolabile CPT-II variants that underlain the persistent high fever-triggered viral infection-associated encephalopathy, multi-organ failure and death. Elevated (C16:0+C18:1)/C2 acylcarnitines ratio and the CPT2 susceptibility variant allele [p.Phe352Cys; p.Val368Ile] were detected. The asymptomatic family members of one patient also had abnormal long-chain acylcarnitines. In our experience of biochemical genetics, the elevated (C16:0+C18:1)/C2 acylcarnitines ratio is unusual and specific for thermolabile CPT-II variants. Allele frequency of [p.Phe352Cys; p.Val368Ile] among Hong Kong Chinese was 0.104, similar to Japanese data, and [p.Phe352Cys] has not been reported in Caucasians. This may explain the Asian-specific phenomenon of thermolabile CPT-II-associated IAE. We successfully demonstrated the thermolabile CPT-II variants in patients with viral infection-associated encephalopathy in another Asian population outside Japanese. The condition is likely under-recognized. With our first cases, it is envisaged that more cases will be diagnosed in subsequent years. The exact pathogenic mechanism of how other factors interplay with thermolabile CPT-II variants and high fever leading to IAE, is yet to be elucidated. Fasting and decreased intake during illness may aggravate the disease. Further studies including high risk and neonatal screening are warranted to investigate its expressivity, penetrance and temperature-dependent behaviors in thermolabile CPT-II carriers. This may lead to discovery of the therapeutic golden window by aggressive antipyretics and L-carnitine administration in avoiding the high mortality and morbidity of IAE.
    Journal of Human Genetics 06/2011; 56(8):617-21. · 2.37 Impact Factor
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    ABSTRACT: Little is known about the antibody response in natural infection by the novel 2009 influenza A (H1N1) virus and its relationship with clinical and virological parameters. The relative lack of background neutralizing antibody against this novel virus provides a unique opportunity for understanding this issue. Case patients presenting with influenza-like illness who were positive for the pandemic H1 gene by reverse transcription polymerase chain reaction were identified. The serum antibody response was assayed by neutralizing antibody titer (NAT) against the virus in 881 convalescent donors. We retrospectively analyzed clinical parameters and viral load. Ninety percent of the 881 convalescent donors had seroprotective titer of 1:40 or greater. The geometric mean titer of donors with convalescent NAT measured between day 21 and 42 was 1:101.1. Multivariate analysis by ordinal regression showed that pneumonia (odds ratio, 3.39; 95% confidence interval, 1.49-7.61; P = .004) and sputum production (odds ratio, 1.75; 95% CI, 1.01-3.01; P = .046) were the 2 independent factors associated with a higher level of convalescent NAT. Being afebrile on influenza presentation was associated with subsequent poor NAT (<1:40) response (P = .04). A positive correlation between the nasopharyngeal viral load on presentation and the convalescent NAT was demonstrated (Spearman correlation rho, 0.238; P = .026). About 10% of these convalescent patients do not have a seroprotective NAT and may benefit from vaccination to prevent reinfection. The convalescent NAT correlated well with the initial viral load and was independently associated with severity of the viral illness, including pneumonia. The findings provide both the clinical and virological markers for identifying potential convalescent plasma donors with high serum NAT, which can be used to produce hyperimmune intravenous immunoglobulin in a randomized treatment trial for patients with severe pandemic H1N1 infection.
    Clinical Infectious Diseases 08/2010; 51(3):274-9. · 9.37 Impact Factor
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    ABSTRACT: Acquired immunodeficiency due to autoantibody against gamma interferon has recently been associated with opportunistic nontuberculous mycobacteriosis, especially among Southeast Asians. We report another 8 cases, all except one apparently immunocompetent hosts who suffered from concomitant or sequential infections by other intracellular pathogens causing penicilliosis, extraintestinal nontyphoidal salmonellosis, and burkholderiosis. The only case with an underlying immunodeficiency syndrome had systemic lupus erythematosus that was quiescent throughout the multiple infective episodes. Eight out of 10 (80.0%) patients with serological evidence of penicilliosis, 5 out of 7 (71.4%) with culture-positive extraintestinal nontyphoidal salmonellosis, 5 out of 28 (17.9%) with serological evidence of melioidosis, and 7 out of 13 (53.8%) with culture-positive nontuberculous mycobacteriosis possessed autoantibody against gamma interferon, whereas only 1 out of 100 patients with systemic lupus erythematosus did. Our study represents the first and largest case series linking this emerging immunodeficiency syndrome with these atypical infections in apparently immunocompetent hosts. Thus, we advocate that any patient with unexplained recurrent or polymicrobial infections due to these intracellular pathogens should be screened for acquired immunodeficiency due to autoantibody against gamma interferon.
    Clinical and vaccine Immunology: CVI 05/2010; 17(7):1132-8. · 2.60 Impact Factor
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    ABSTRACT: Although high-density resequencing microarray is useful for detection and tracking the evolution of viruses associated with respiratory tract infections, no report on using this technology for the detection of viruses in patients with conjunctivitis is available. To test if high-density resequencing microarray can be applied to detection of viruses in conjunctival swabs for patients with conjunctivitis. In this prospective proof-of-concept study, every 4 or 5 bacterial culture-negative conjunctival swab samples were pooled and subject to viral detection using TessArray Resequencing Pathogen Microarrays-Flu 3.1 (RPM-Flu-3.1). Results were compared with human adenovirus (HAdV) hexon gene PCR sequencing and viral culture. Thirty-two of the 38 conjunctival swab samples were bacterial culture-negative. Four of the 7 pooled samples were positive for HAdV using RPM-Flu-3.1. Hexon gene PCR sequencing on the 38 original individual samples showed that 3 and 4 samples contained HAdVs species D and B respectively. All the 6 samples that were positive for hexon gene PCR but negative for bacterial culture were also positive by the resequencing microarray. Viral culture was positive for HAdV type 3 in 1 sample, which was also positive by PCR and resequencing microarray. Resequencing microarray is as sensitive as PCR for detection of HAdV in conjunctival swabs. Unlike viral culture and hexon gene PCR sequencing, resequencing microarray was not able to differentiate the type and species of HAdV. Development of microarrays for conjunctivitis can be performed for rapid diagnosis of the viral cause of conjunctivitis.
    Journal of clinical virology: the official publication of the Pan American Society for Clinical Virology 03/2010; 47(3):282-5. · 3.12 Impact Factor
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    ABSTRACT: A bacterial collection (n=249) obtained in Hong Kong from 2002 to 2004 was used to investigate the molecular epidemiology of aminoglycoside resistance among Escherichia coli isolates from humans and food-producing animals. Of these, 89 isolates were gentamicin-sensitive (human n=60, animal n=29) and 160 isolates were gentamicin-resistant (human n=107, animal n=53). Overall, 84.1% (90/107) and 75.5% (40/53) of the gentamicin-resistant isolates from human and animal sources, respectively, were found to possess the aacC2 gene. The aacC2 gene for 20 isolates (10 each for human and animal isolates) was sequenced. Two alleles were found that were equally distributed in human and animal isolates. PFGE showed that the gentamicin-resistant isolates exhibited diverse patterns with little clonality. In some isolates, the aacC2 gene was encoded on large transferable plasmids of multiple incompatibility groups (IncF, IncI1 and IncN). An IncFII plasmid of 140 kb in size was shared by one human and three animal isolates. In summary, this study showed that human and animal isolates share the same pool of resistance genes.
    Journal of Medical Microbiology 02/2010; 59(Pt 6):702-7. · 2.30 Impact Factor
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    ABSTRACT: A prospective multicenter study was conducted to assess the epidemiology of antimicrobial resistance among uropathogens causing uncomplicated cystitis. Adult women with clinical diagnosis of uncomplicated cystitis were enrolled from 54 participating centers distributed all over Hong Kong during 2006 to 2008. A positive urine culture was found in 59.5% (352/592) patients. The patients had mean age of 44.9 years, and most (89.2%) were otherwise healthy. The most prevalent causative organism was Escherichia coli (77%), followed by other Enterobacteriaceae (14.2%), staphylococci (5.1%), and other Gram-positive bacteria (3.7%). The resistance rates of E. coli to co-trimoxazole and ciprofloxacin were 29.5% and 12.9%, respectively, and 14 isolates (5.2%) were confirmed as extended-spectrum beta-lactamase (ESBL) producers. Of the ESBL producers, molecular studies showed CTX-M-14, CTX-M-24, or CTX-M-9. Nitrofurantoin and fosfomycin were active against >90% of the isolates, regardless of resistance phenotypes for other drugs. Pulsed-field gel electrophoresis of representative isolates showed that the antibiotic-resistant strains were genetically diverse. Patients with history of recent antibiotic use were significantly more likely to have infection by E. coli with co-trimoxazole resistance (odds ratio [OR], 2.8; 95% confidence interval [CI], 1.4-5.7; P = 0.003) and ciprofloxacin resistance (OR, 2.5; 95% CI, 1.1-5.8; P = 0.03). Knowledge of the resistance data and risk factors could inform better use of antibiotics for empiric therapy for acute uncomplicated cystitis.
    Diagnostic microbiology and infectious disease 06/2009; 66(1):87-93. · 2.45 Impact Factor
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    ABSTRACT: To determine the antibiotic susceptibility patterns of 60 strains of Laribacter hongkongensis isolated from humans and fish to eight antibiotics and compare the results obtained from broth microdilution, Etest and disc diffusion susceptibility testing. The susceptibilities of 60 isolates of L. hongkongensis from humans with gastroenteritis and fish to eight antibiotics were tested by three methods [broth microdilution (reference method), Etest and disc diffusion] and their results were compared. All isolates were susceptible to imipenem and ciprofloxacin by all three methods, except for one strain which was resistant to ciprofloxacin by broth microdilution. All were susceptible to ampicillin/sulbactam by Etest and disc diffusion, but eight were resistant by broth microdilution. By broth microdilution, 90%, 100%, 46.7%, 100% and 8.3% of isolates were resistant to ampicillin, ceftriaxone, cefuroxime, erythromycin and tetracycline, respectively. Although broth microdilution generally yielded higher MICs of beta-lactams, MICs obtained with Etest were in good correlation with broth microdilution for all drugs except ampicillin/sulbactam, with >90% agreement within 2 log(2) dilutions for imipenem, ciprofloxacin, erythromycin and tetracycline. Comparison of susceptibilities between broth microdilution and the other two methods showed the highest (>95%) percentage agreement for imipenem, ciprofloxacin and tetracycline. The highest discrepancies were observed with erythromycin (58.3% agreement), with an apparent increase in susceptibility by disc diffusion. A higher proportion of human isolates than fish isolates were tetracycline-resistant by all three tests (P=0.022). Etest and disc diffusion appear to be reliable for evaluation of susceptibilities of L. hongkongensis to imipenem, ciprofloxacin and tetracycline. However, these methods may underestimate resistance to other beta-lactams.
    Journal of Antimicrobial Chemotherapy 02/2009; 63(4):704-8. · 5.34 Impact Factor
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    ABSTRACT: We investigated the occurrence and diversity of extended-spectrum beta-lactamase (ESBL) enzymes among antibiotic-resistant Escherichia coli and Klebsiella pneumoniae isolates obtained from human feces. All ESBL-positive isolates were characterized at the molecular level by polymerase chain reaction, sequencing and pulsed-field gel electrophoresis (PFGE). Eight of 46 antibiotic-resistant E. coli (6 from children and 2 from adults) and 4 of 8 K. pneumoniae (all from adults) isolates were found to be ESBL-positive by the double-disk synergy test. Seven isolates were found to have CTX-M-14, 2 each had CTX-M-24 and CTX-M-38, and 1 had CTX-M-9. In addition, 8 isolates were found to carry TEM-1b or TEM-1c. No SHV-type enzyme was found among the E. coli strains. In 9 strains, the plasmidic bla(CTX-M) determinants were transferable to E. coli by conjugation. Analysis by PFGE showed evidence of clonal and non-clonal spread. The present study shows fecal carriage of organisms producing bla(CTX-M) determinants and underscores the role that commensals could play as a reservoir for their dissemination.
    Journal of microbiology, immunology, and infection = Wei mian yu gan ran za zhi 11/2008; 41(5):428-32. · 1.63 Impact Factor
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    ABSTRACT: This prospective study assessed the epidemiology of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) among patients with purulent skin and soft tissue infections (SSTIs) in Hong Kong. Among 298 patients with SSTIs, 10.4% (13/125) of all S. aureus isolates and 5% (12/241) of all abscesses were attributed to pvl-positive CA-MRSA. Overall, 77% and 69.9% of CA-MRSA and methicillin-sensitive S. aureus (MSSA) were susceptible to erythromycin, 77% and 74.8% to clindamycin, 100% and 97.1% to minocycline, and 100% and 98.1% to rifampin, respectively. Filipino ethnicity was the only clinical and epidemiologic factor significantly associated with CA-MRSA infection (odds ratio, 14.8; 95% confidence interval, 3.3-70.0; P < 0.001). Pulsed-field gel electrophoresis analysis showed that 6 CA-MRSA isolates belonged to the ST30-HKU100 clone, 5 belonged to the ST59-HKU200 clone, and 1 was singleton. Features of HKU100 isolates include SCCmec type IV, agr3, spa t019, and pan-susceptibility to non-beta-lactam antibiotics. In contrast, HKU200 isolates are characterized by having SCCmec type IV or V, agr4, spa t437, and variable non-beta-lactam susceptibility profiles. The major CA-MRSA spa types were shared by a minority of the MSSA.
    Diagnostic Microbiology and Infectious Disease 07/2008; 61(3):245-50. · 2.26 Impact Factor
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    ABSTRACT: To compare the performance of polymerase chain reaction versus conventional methods (cell culture and direct immunofluorescent assay) in diagnosing neonatal chlamydial conjunctivitis and their correlations to the severity of conjunctivitis. Consecutive cases of neonatal conjunctivitis were recruited over a year. Both eyes were clinically graded according to the severity of conjunctivitis and investigated using the three aforementioned chlamydial tests. Neonatal chlamydial conjunctivitis was assumed if one of these three tests was positive and there was clinical improvement after treatment. Sensitivity and specificity of each of the tests were analyzed. Three hundred sixty-eight sets of chlamydial tests were done for 184 neonates. The percentage of positive results was 93.8% and 71.9% for polymerase chain reaction and conventional methods, respectively. Using positive results in either cell culture or direct immunofluorescent assay as a standard to diagnose neonatal chlamydial conjunctivitis, the sensitivity and specificity of polymerase chain reaction were 92.0% and 97.7%, respectively. If we used polymerase chain reaction as a standard, the sensitivity and specificity of cell culture were 73.3% and 99.7%, respectively. A discrepancy was noted in the number of positive results between polymerase chain reaction and conventional methods in milder disease. Polymerase chain reaction might have a higher sensitivity and similar specificity in diagnosing neonatal chlamydial conjunctivitis compared to conventional methods, and it has an additional advantage as a diagnostic tool in mild disease.
    Journal of Pediatric Ophthalmology & Strabismus 01/2008; 45(4):234-9. · 0.86 Impact Factor
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    ABSTRACT: This study evaluated the antimicrobial resistance profile of outpatient urinary Escherichia coli isolated from women obtained throughout Hong Kong during 2004-2005. Of 1067 single patient isolates analyzed, 60.1% were resistant to ampicillin, 34% were resistant to co-trimoxazole, and 22.1% were resistant to ciprofloxacin. Thirty-four (6.6%) of 519 isolates in 2004 and 55 (10%) of 548 isolates in 2005 were extended-spectrum beta-lactamase (ESBL) producers with a CTX-M phenotype. Rates of non-beta-lactam resistance and ESBL production were strongly influenced by patient age. The age-stratified rates for dual co-trimoxazole and ciprofloxacin resistance and for ESBL production were 10.9% and 7.6% in women aged 18-35 years, 13% and 6.9% in women aged 36-50 years, 20.4% and 8.8% in women aged 51-64 years, and 23.7% and 11.8% in women aged > or =65 years, respectively. Nitrofurantoin and fosfomycin remain active against >90% of the isolates, irrespective of the resistance phenotypes for other drugs. Our results documented the emergence of problematic resistance phenotypes among community urinary E. coli and highlight the need to explore strategies for their containment.
    Diagnostic Microbiology and Infectious Disease 12/2007; 59(4):439-45. · 2.26 Impact Factor
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    ABSTRACT: A highly reproducible and discriminative typing system is essential for better understanding of the epidemiology of Penicillium marneffei, the most important thermal dimorphic fungus causing respiratory, skin, and systemic mycosis in Southeast Asia. The sequences of 11 housekeeping genes were identical among 10 strains of P. marneffei, but those of MP1 and its 13 homologues, a novel superfamily of mannoproteins in the subdivision Pezizomycotina of Ascomycetes, mostly species of Penicillium and Aspergillus, showed significant variations. Therefore, a multilocus sequence typing (MLST) system for P. marneffei was constructed using MP1 (549 bp) and the four of its homologues (MPLP4 [337 bp], MPLP7 [347 bp], MPLP10 [546 bp], and MPLP13 [422 bp]) that showed the greatest variations. Among the 2,201 bp of the five loci, 183 polymorphic sites were observed in 44 strains of P. marneffei. The median number of alleles at each locus was five (range, 5 [MPLP4, MPLP7, and MPLP13] to 15 [MPLP10]). Four of the five genes had nonsynonymous substitution/synonymous substitution (d(n)/d(s)) ratios of >1. A total of 35 different sequence types (STs) were assigned to the 44 P. marneffei isolates, with 28 of the 35 STs identified only once. The discriminatory power was 0.9884. MP1 and its homologues were better than housekeeping genes for MLST in P. marneffei. Due to their more rapid evolutionary rates, lineage-specific genes may be better candidates than housekeeping genes for sequence-based typing, especially in microbes that evolve slowly or have evolved recently.
    Journal of Clinical Microbiology 12/2007; 45(11):3647-54. · 4.07 Impact Factor

Publication Stats

662 Citations
146.20 Total Impact Points

Institutions

  • 2003–2013
    • Tuen Mun Hospital
      • • Department of Clinical Pathology
      • • Department of Paediatrics and Adolescent Medicine
      • • Department of Accident and Emergency
      Hong Kong, Hong Kong
  • 2002–2013
    • The University of Hong Kong
      • Department of Microbiology
      Hong Kong, Hong Kong
  • 2002–2010
    • Queen Mary Hospital
      Hong Kong, Hong Kong