Transmission Patterns of Co-Circulation of Omicron Sub-Lineages in Hong Kong SAR, China, a City with Rigorous Social Distancing Measures, in 2022.

OBJECTIVE: This study aimed to characterize the changing landscape of circulating SARS-CoV-2 lineages in the local community of Hong Kong throughout 2022. We examined how adjustments to quarantine arrangements influenced the transmission pattern of Omicron variants in a city with relatively rigorous social distancing measures at that time. METHODS: In 2022, a total of 4684 local SARS-CoV-2 genomes were sequenced using the Oxford Nanopore GridION sequencer. SARS-CoV-2 consensus genomes were generated by MAFFT, and the maximum likelihood phylogeny of these genomes was determined using IQ-TREE. The dynamic changes in lineages were depicted in a time tree created by Nextstrain. Statistical analysis was conducted to assess the correlation between changes in the number of lineages and adjustments to quarantine arrangements. RESULTS: By the end of 2022, a total of 83 SARS-CoV-2 lineages were identified in the community. The increase in the number of new lineages was significantly associated with the relaxation of quarantine arrangements (One-way ANOVA, F(5, 47) = 18.233, p < 0.001)). Over time, Omicron BA.5 sub-lineages replaced BA.2.2 and became the predominant Omicron variants in Hong Kong. The influx of new lineages reshaped the dynamics of Omicron variants in the community without fluctuating the death rate and hospitalization rate (One-way ANOVA, F(5, 47) = 2.037, p = 0.091). CONCLUSION: This study revealed that even with an extended mandatory quarantine period for incoming travelers, it may not be feasible to completely prevent the introduction and subsequent community spread of highly contagious Omicron variants. Ongoing molecular surveillance of COVID-19 remains essential to monitor the emergence of new recombinant variants.

Comparison of carbapenem MIC for NDM-producing Enterobacterales by different AST methods.

Introduction: This study compared the performance of MIC test strip (ETEST), automated AST card (Vitek 2) and broth microdilution (BMD) in determining carbapenem susceptibility and MIC values of NDM-producing Enterobacterales. Methods: NDM-producing Enterobacterales recovered from clinical specimens were included. The presence of blaNDM was confirmed by PCR. Identification of bacterial isolates was done by MALDI-TOF. Phenotypic susceptibility to three carbapenems (ertapenem, imipenem and meropenem) was tested by BMD, ETEST and Vitek 2. MIC values were interpreted in accordance with CLSI M100 (2022 edition). Using BMD as the reference standard, the essential agreement (EA), categorical agreement (CA), very major error (VME) and major error (ME) rates were evaluated. Results: Forty-seven NDM-producing Enterobacterales isolates were included, 44 of which were Escherichia coli. The EA of Vitek 2 was 97.9% for ertapenem, 25.5% for meropenem and 42.6% for imipenem. Using Vitek 2, there were 0% VMEs across all three carbapenems tested. The EA of ETEST was 53.2% for ertapenem, 55.3% for imipenem and 36.2% for meropenem. The rates of VMEs for ETEST were high too (ertapenem 8.5%, meropenem 36.2%, imipenem 26.1%). The MIC values obtained from Vitek 2 were consistently higher than those from BMD, while MICs from ETEST were consistently lower than those from BMD. Conclusions: The VME rate for ETEST was unacceptably high when BMD was used as the standard for comparison. Vitek 2 had acceptable EA and CA for ertapenem when BMD was used as the standard for comparison. For meropenem and imipenem, neither of the methods (ETEST, Vitek 2) showed acceptable EA and CA when compared with BMD.

Clean clothes or dirty clothes? Outbreak investigation of carbapenem-resistant Acinetobacter baumannii related to laundry contamination through multilocus sequence typing (MLST).

OBJECTIVE: To investigate the source in an outbreak of carbapenem-resistant Acinetobacter baumannii (CRA) in a general hospital due to contamination of a laundry evaporative cooler and the laundry environment using multilocus sequence typing (MLST). METHODS: For CRA culture, clinical samples were collected from infected patients and close contacts, and environmental sampling was performed in patient surroundings and laundry facilities. MLST was used for the molecular typing of representative CRA isolates. Bacterial isolates with identical sequence types were considered epidemiologically linked and attributable to the same source. OXA genes in Acinetobacter baumannii were detected using polymerase chain reaction (PCR). RESULTS: In total, 58 patients were affected in this outbreak. The mean patient age was 75.3, and 50% were female. The most common diagnoses at admission were skin and soft-tissue infection (n = 12, 20.7%) and pneumonia (n = 12, 20.7%). OXA-23 was positive in 64.7% of isolates. A CRA isolate from the evaporative cooler in the laundry was identical to that of 11 patients across 3 wards, belonging to ST345. Isolates from 3 laundry linen racks were identical to those of 7 patients from 3 wards, classified as ST1145. Isolates found on another linen rack and a pajama shelf were identical to isolates from 3 other patients from 2 wards, belonging to ST2207. There was no significant difference between sequence type distributions of clinical and environmental isolates (P = .12), indicating high likelihood of CRA originating from the same source. CONCLUSIONS: MLST confirmed that contamination of the laundry evaporative cooler and surrounding environment caused a polyclonal CRA hospital outbreak. Hospital laundry is an important area for infection control and outbreak investigations of CRA.

The clinical utility of Nanopore 16S rRNA gene sequencing for direct bacterial identification in normally sterile body fluids.

The prolonged incubation period of traditional culture methods leads to a delay in diagnosing invasive infections. Nanopore 16S rRNA gene sequencing (Nanopore 16S) offers a potential rapid diagnostic approach for directly identifying bacteria in infected body fluids. To evaluate the clinical utility of Nanopore 16S, we conducted a study involving the collection and sequencing of 128 monomicrobial samples, 65 polymicrobial samples, and 20 culture-negative body fluids. To minimize classification bias, taxonomic classification was performed using 3 analysis pipelines: Epi2me, Emu, and NanoCLUST. The result was compared to the culture references. The limit of detection of Nanopore 16S was also determined using simulated bacteremic blood samples. Among the three classifiers, Emu demonstrated the highest concordance with the culture results. It correctly identified the taxon of 125 (97.7%) of the 128 monomicrobial samples, compared to 109 (85.2%) for Epi2me and 102 (79.7%) for NanoCLUST. For the 230 cultured species in the 65 polymicrobial samples, Emu correctly identified 188 (81.7%) cultured species, compared to 174 (75.7%) for Epi2me and 125 (54.3%) for NanoCLUST. Through ROC analysis on the monomicrobial samples, we determined a threshold of relative abundance at 0.058 for distinguishing potential pathogens from background in Nanopore 16S. Applying this threshold resulted in the identification of 107 (83.6%), 117 (91.4%), and 114 (91.2%) correctly detected samples for Epi2me, Emu, and NanoCLUST, respectively, in the monomicrobial samples. Nanopore 16S coupled with Epi2me could provide preliminary results within 6 h. However, the ROC analysis of polymicrobial samples exhibited a random-like performance, making it difficult to establish a threshold. The overall limit of detection for Nanopore 16S was found to be about 90 CFU/ml.

Comparison of PneumID real-time PCR assay with Amplex eazyplex LAMP assay for laboratory diagnosis of Pneumocystis jirovecii Pneumonia.

We compared PneumID PCR with Amplex eazyplex LAMP assay for the diagnosis of Pneumocystis jirovecii pneumonia (PJP). Both assays enable accurate diagnosis of definite PJP. Cut-off cycle threshold of the PneumID assay was < 26.68 while the cut-off time-to-positivity of the eazyplex assay was 16:02 (minutes:seconds). The positive and negative percentage agreement of eazyplex assay with PneumID assay was 75.0% and 100.0% respectively, while the overall agreement was substantial with kappa = 0.80. For both assays, establishment of cut-off values to differentiate probable PJP from colonization was not feasible as results overlapped.

Both PneumID PCR and Amplex eazyplex LAMP assay enable accurate diagnosis of definite Pneumocystis jirovecii pneumonia (PJP). PneumID assay was more sensitive than eazyplex assay for detection of P. jirovecii. However, differentiation between probable PJP from colonization was not feasible.

Genomic Epidemiology of Multidrug-Resistant Nontyphoidal Salmonella in Young Children Hospitalized for Gastroenteritis.

Nontyphoidal Salmonella (NTS) gastroenteritis in children remains a significant burden on health care and constitutes a majority of all admissions for Salmonella infections in public hospitals in Hong Kong. In this prospective study, 41% of 241 children hospitalized with gastroenteritis from three public hospitals during 2019 were culture confirmed to have NTS infection. These Salmonella isolates were whole-genome sequenced and in silico predicted for their serovars/serotypes using the Salmonella In Silico Typing Resource (SISTR) and SeqSero1, and the antimicrobial resistance (AMR) genes were determined. Phylogenetic analysis revealed three major clades belonging to Salmonella enterica serovar Enteritidis sequence type 11 (ST11) (43%), multidrug-resistant (MDR) S. Typhimurium ST19 (12%) and its monophasic variant ST34 (25%), and mostly singletons of 15 other serovars. MDR S. Typhimurium and its variant were more common in infants <24 months of age and possessed genotypic resistance to five antimicrobial agents, including ampicillin (A), chloramphenicol (C), aminoglycosides (Am), sulfonamides (Su), and tetracyclines (T). Older children were more often infected with S. Enteritidis, which possessed distinct genotypic resistance to AAmSu and fluoroquinolones. In addition, 3% of the isolates possessed extended-spectrum beta-lactamase (ESBL) CTX-M genes, while one isolate (1%) harboring the carbapenemase gene blaNDM-1 was identified. Our findings provide a more complete genomic epidemiological insight into NTS causing gastroenteritis and identify a wider spectrum of determinants of resistance to third-generation beta-lactams and carbapenems, which are often not readily recognized. With high rates of multidrug-resistant NTS from studies in the Asia-Pacific region, the rapid and reliable determination of serovars and resistance determinants using whole-genome sequencing (WGS) is invaluable for enhancing public health interventions for infection prevention and control. IMPORTANCE Nontyphoidal Salmonella (NTS) gastroenteritis is a foodborne disease with a large global burden. Antimicrobial resistance (AMR) among foodborne pathogens is an important public health concern, and multidrug-resistant (MDR) Salmonella is prevalent in Southeast Asia and China. Using whole-genome sequencing, this study highlights the relationship of the MDR Salmonella serotypes and the diverse range of Salmonella genotypes that contaminate our food sources and contribute to disease in this locality. The findings update our understanding of Salmonella epidemiology and associated MDR determinants to enhance the tracking of foodborne pathogens for public health and food safety.

Current and Past Infections of HBV Do Not Increase Mortality in Patients With COVID-19.

BACKGROUND AND AIMS: We compared risk of acute liver injury and mortality in patients with COVID-19 and current, past, and no HBV infection. APPROACH AND RESULTS: This was a territory-wide retrospective cohort study in Hong Kong. Patients with COVID-19 between January 23, 2020, and January 1, 2021, were identified. Patients with hepatitis C or no HBsAg results were excluded. The primary outcome was mortality. Acute liver injury was defined as alanine aminotransferase or aspartate aminotransferase ≥2 × upper limit of normal (ULN; i.e., 80 U/L), with total bilirubin ≥2 × ULN (i.e., 2.2 mg/dL) and/or international normalized ratio ≥1.7. Of 5,639 patients included, 353 (6.3%) and 359 (6.4%) had current and past HBV infection, respectively. Compared to patients without known HBV exposure, current HBV-infected patients were older and more likely to have cirrhosis. Past HBV-infected patients were the oldest, and more had diabetes and cardiovascular disease. At a median follow-up of 14 (9-20) days, 138 (2.4%) patients died; acute liver injury occurred in 58 (1.2%), 8 (2.3%), and 11 (3.1%) patients with no, current, and past HBV infection, respectively. Acute liver injury (adjusted HR [aHR], 2.45; 95% CI, 1.52-3.96; P < 0.001), but not current (aHR, 1.29; 95% CI, 0.61-2.70; P = 0.507) or past (aHR, 0.90; 95% CI, 0.56-1.46; P = 0.681) HBV infection, was associated with mortality. Use of corticosteroid, antifungal, ribavirin, or lopinavir-ritonavir (adjusted OR [aOR], 2.55-5.63), but not current (aOR, 1.93; 95% CI, 0.88-4.24; P = 0.102) or past (aOR, 1.25; 95% CI, 0.62-2.55; P = 0.533) HBV infection, was associated with acute liver injury. CONCLUSION: Current or past HBV infections were not associated with more liver injury and mortality in COVID-19.

Risks of AKI and Major Adverse Clinical Outcomes in Patients with Severe Acute Respiratory Syndrome or Coronavirus Disease 2019.

BACKGROUND: Severe acute respiratory syndrome (SARS) and coronavirus disease 2019 (COVID-19) are closely related. The effect of AKI on the clinical outcomes of these two conditions is unclear. METHODS: This retrospective, territory-wide cohort study used an electronic public healthcare database in Hong Kong to identify patients with SARS or COVID-19 by diagnosis codes, virologic results, or both. The primary endpoint was a composite of intensive care unit admission, use of invasive mechanical ventilation, and/or death. RESULTS: We identified 1670 patients with SARS and 1040 patients with COVID-19 (median ages, 41 versus 35 years, respectively). Among patients with SARS, 26% met the primary endpoint versus 5.3% of those with COVID-19. Diabetes mellitus, abnormal liver function, and AKI were factors significantly associated with the primary endpoint among patients with either SARS or COVID-19. Among patients with SARS, 7.9%, 2.1%, and 3.7% developed stage 1, stage 2, and stage 3 AKI, respectively; among those with COVID-19, 6.6%, 0.4%, and 1.1% developed stage 1, stage 2, and stage 3 AKI, respectively. In both groups, factors significantly associated with AKI included diabetes mellitus and hypertension. Among patients with AKI, those with COVID-19 had a lower rate of major adverse clinical outcomes versus patients with SARS. Renal function recovery usually occurred within 30 days after an initial AKI event. CONCLUSIONS: AKI rates were higher among patients with SARS than those with COVID-19. AKI was associated with major adverse clinical outcomes for both diseases. Patients with diabetes mellitus and abnormal liver function were also at risk of developing severe consequences after SARS and COVID-19 infection.

Evaluation of the Xpert Xpress SARS-CoV-2/Flu/RSV Assay for Simultaneous Detection of SARS-CoV-2, Influenza A and B Viruses, and Respiratory Syncytial Virus in Nasopharyngeal Specimens.

Patients infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), influenza A (flu A), influenza B (flu B), and respiratory syncytial virus (RSV) have overlapping clinical presentations, but the approaches to treatment and management of infections caused by these viruses are different. Therefore, rapid diagnosis in conjunction with infection prevention measures is important to prevent transmission of the diseases. Recently, a new Xpert Xpress SARS-CoV-2/Flu/RSV (Xpert 4-in-1) assay enables the detection and differentiation of SARS-CoV-2, flu A, flu B, and RSV in upper respiratory tract specimens. In this study, we evaluated the performance of the Xpert 4-in-1 assay by comparing it with that of the Xpert Xpress SARS-CoV-2 and Xpert Xpress Flu/RSV assays for the detection of the four viruses in nasopharyngeal (NP) specimens. A total of 279 NP specimens, including 66, 56, 64, and 53 specimens positive for SARS-CoV-2, flu A, flu B, and RSV, respectively, were included. The Xpert 4-in-1 assay demonstrated high concordance with the comparator assays, with overall agreement for SARS-CoV-2, flu A, flu B, and RSV at 99.64%, 100%, 99.64%, and 100%, respectively, and a high Cohen's kappa (κ) value ranging from 0.99 to 1.00, indicating an almost perfect correlation between assays. The cycle threshold value association between positive samples also showed a good correlation between assays. In conclusion, the overall performance of the Xpert 4-in-1 assay was highly comparable to that of the Xpert SARS-CoV-2 and Xpert Flu/RSV assays for the detection and differentiation of SARS CoV-2, flu A, flu B, and RSV in NP specimens.

Deep learning model for prediction of extended-spectrum beta-lactamase (ESBL) production in community-onset Enterobacteriaceae bacteraemia from a high ESBL prevalence multi-centre cohort.

Adequate empirical antimicrobial coverage is instrumental in clinical management of community-onset Enterobacteriaceae bacteraemia in areas with high ESBL prevalence, while balancing the risk of carbapenem overuse and emergence of carbapenem-resistant organisms. It is unknown whether machine learning offers additional advantages to conventional statistical methods in prediction of ESBL production. To develop a validated model to predict ESBL production in Enterobacteriaceae causing community-onset bacteraemia. 5625 patients with community-onset bacteraemia caused by Escherichia coli, Klebsiella species and Proteus mirabilis during 1 January 2015-31 December 2019 from three regional hospitals in Hong Kong were included in the analysis, after exclusion of blood cultures obtained beyond 48 h of admission. The prevalence of ESBL-producing Enterobacteriaceae was 23.7% (1335/5625). Deep neural network and other machine learning algorithms were compared against conventional statistical model via multivariable logistic regression. Primary outcomes compared consisted of predictive model area under curve of receiver-operator characteristic curve (AUC), and macro-averaged F1 score. Secondary outcomes included sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). Deep neural network yielded an AUC of 0.761 (95% CI 0.725-0.797) and F1 score of 0.661 (95% CI 0.633-0.689), which was superior to logistic regression (AUC 0.667 (95% CI 0.627-0.707), F1 score 0.596 (95% CI 0.567-0.625)). Deep neural network had a specificity of 91.5%, sensitivity of 37.5%, NPV of 82.5%, and PPV of 57.9%. Deep neural network is superior to logistic regression in predicting ESBL production in Enterobacteriaceae causing community-onset bacteraemia in high-ESBL prevalence area. Machine learning offers clinical utility in guiding judicious empirical antibiotics use.

Significantly Lower Case-fatality Ratio of Coronavirus Disease 2019 (COVID-19) than Severe Acute Respiratory Syndrome (SARS) in Hong Kong-A Territory-Wide Cohort Study.

BACKGROUND: The case-fatality ratios (CFR) of coronavirus disease 2019 (COVID-19) and severe acute respiratory syndrome (SARS) appeared to differ substantially. We aimed to compare the CFR and its predictors of COVID-19 and SARS patients using a territory-wide cohort in Hong Kong. METHODS: This was a territory-wide retrospective cohort study using data captured from all public hospitals in Hong Kong. Laboratory-confirmed COVID-19 and SARS patients were identified. The primary endpoint was a composite endpoint of intensive care unit admission, use of mechanical ventilation, and/or death. RESULTS: We identified 1013 COVID-19 patients (mean age, 38.4 years; 53.9% male) diagnosed from 23 January to 14 April 2020 and 1670 SARS patients (mean age, 44.4 years; 44.0% male) from March to June 2003. Fifty-five (5.4%) COVID-19 patients and 432 (25.9%) SARS patients had reached the primary endpoint in 30 days. By 30 June 2003, 286 SARS patients had died (CFR, 17.1%). By 7 June 2020, 4 COVID-19 patients had died (CFR, 0.4%). After adjusting for demographic and clinical parameters, COVID-19 was associated with a 71% lower risk of primary endpoint compared with SARS (adjusted hazard ratio, 0.29; 95% confidence interval, .21-.40; P < .0001). Age, diabetes mellitus, and laboratory parameters (high lactate dehydrogenase, high C-reactive protein, and low platelet count) were independent predictors of the primary endpoint in COVID-19 patients, whereas use of antiviral treatments was not associated with primary endpoint. CONCLUSIONS: The CFR of COVID-19 was 0.4%. Age and diabetes were associated with worse outcomes, whereas antiviral treatments were not.

Liver injury is independently associated with adverse clinical outcomes in patients with COVID-19.

OBJECTIVE: Data on serial liver biochemistries of patients infected by different human coronaviruses (HCoVs) are lacking. The impact of liver injury on adverse clinical outcomes in coronavirus disease 2019 (COVID-19) patients remains unclear. DESIGN: This was a retrospective cohort study using data from a territory-wide database in Hong Kong. COVID-19, severe acute respiratory syndrome (SARS) and other HCoV patients were identified by diagnosis codes and/or virological results. Alanine aminotransferase (ALT)/aspartate aminotransferase (AST) elevation was defined as ALT/AST ≥2 × upper limit of normal (ie, 80 U/L). The primary end point was a composite of intensive care unit (ICU) admission, use of invasive mechanical ventilation and/or death. RESULTS: We identified 1040 COVID-19 patients (mean age 38 years, 54% men), 1670 SARS patients (mean age 44 years, 44% men) and 675 other HCoV patients (mean age 20 years, 57% men). ALT/AST elevation occurred in 50.3% SARS patients, 22.5% COVID-19 patients and 36.0% other HCoV patients. For COVID-19 patients, 53 (5.1%) were admitted to ICU, 22 (2.1%) received invasive mechanical ventilation and 4 (0.4%) died. ALT/AST elevation was independently associated with primary end point (adjusted OR (aOR) 7.92, 95% CI 4.14 to 15.14, p<0.001) after adjusted for albumin, diabetes and hypertension. Use of lopinavir-ritonavir ±ribavirin + interferon beta (aOR 1.94, 95% CI 1.20 to 3.13, p=0.006) and corticosteroids (aOR 3.92, 95% CI 2.14 to 7.16, p<0.001) was independently associated with ALT/AST elevation. CONCLUSION: ALT/AST elevation was common and independently associated with adverse clinical outcomes in COVID-19 patients. Use of lopinavir-ritonavir, with or without ribavirin, interferon beta and/or corticosteroids was independently associated with ALT/AST elevation.

Deep throat saliva as an alternative diagnostic specimen type for the detection of SARS-CoV-2.

Nasopharyngeal swabs (NPS) are widely accepted as specimens for the detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in the current pandemic of coronavirus disease 2019. However, the collection procedures for NPS specimens causes sneezing and coughing in most patients, which generate droplets or aerosol particles that are hazardous to the healthcare workers collecting these specimens. In this study, 95 patient-matched paired deep throat saliva (DTS) and NPS specimens from 62 patients were analyzed. Samples were tested for SARS-CoV-2 by reverse-transcription polymerase chain reaction (RT-PCR). The rates of detection for DTS (53.7%) and NPS (47.4%) samples were comparable (P = .13). It is important to note that the patients should be clearly instructed or supervised during DTS collection. In conclusion, SARS-CoV-2 detection by RT-PCR was equivalent in DTS and NPS specimens.

Effectiveness of antimicrobial hospital curtains on reducing bacterial contamination-A multicenter study.

OBJECTIVE: To determine the efficacy of 2 types of antimicrobial privacy curtains in clinical settings and the costs involved in replacing standard curtains with antimicrobial curtains. DESIGN: A prospective, open-labeled, multicenter study with a follow-up duration of 6 months. SETTING: This study included 12 rooms of patients with multidrug-resistant organisms (MDROs) (668 patient bed days) and 10 cubicles (8,839 patient bed days) in the medical, surgical, neurosurgical, orthopedics, and rehabilitation units of 10 hospitals. METHOD: Culture samples were collected from curtain surfaces twice a week for 2 weeks, followed by weekly intervals. RESULTS: With a median hanging time of 173 days, antimicrobial curtain B (quaternary ammonium chlorides [QAC] plus polyorganosiloxane) was highly effective in reducing the bioburden (colony-forming units/100 cm2, 1 vs 57; P < .001) compared with the standard curtain. The percentages of MDRO contamination were also significantly lower on antimicrobial curtain B than the standard curtain: methicillin-resistant Staphylococcus aureus, 0.5% vs 24% (P < .001); carbapenem-resistant Acinetobacter spp, 0.2% vs 22.1% (P < .001); multidrug-resistant Acinetobacter spp, 0% vs 13.2% (P < .001). Notably, the median time to first contamination by MDROs was 27.6 times longer for antimicrobial curtain B than for the standard curtain (138 days vs 5 days; P = .001). CONCLUSIONS: Antimicrobial curtain B (QAC plus polyorganosiloxane) but not antimicrobial curtain A (built-in silver) effectively reduced the microbial burden and MDRO contamination compared with the standard curtain, even after extended use in an active clinical setting. The antimicrobial curtain provided an opportunity to avert indirect costs related to curtain changing and laundering in addition to improving patient safety.

Surveillance of antibiotic resistance among common Clostridium difficile ribotypes in Hong Kong.

Incidence of Clostridium difficile infection (CDI) is rapidly increasing and it poses a major health burden globally. However, data regarding the epidemiology of CDI in Asia are limited. We aimed to characterize the antimicrobial susceptibility patterns of common ribotypes of toxigenic C. difficile in Hong Kong. Fifty-three PCR ribotypes were identified among 284 toxigenic C. difficile clinical isolates. The five most prevalent ribotypes were 002 (13%), 017 (12%), 014 (10%), 012 (9.2%), and 020 (9.5%). All tested C. difficile strains remained susceptible to metronidazole, vancomycin, meropenem and piperacillin/tazobactam, but highly resistant to cephalosporins. Of the fluoroquinolones, highest resistance to ciprofloxacin was observed (99%), followed by levofloxacin (43%) and moxifloxacin (23%). The two newly emerged PCR ribotypes, 017 and 002, demonstrated high levels of co-resistance towards clindamycin, tetracycline, erythromycin and moxifloxacin. PCR ribotypes 017 and 002 with multi-drug resistance are rapidly emerging and continuous surveillance is important to monitor the epidemiology of C. difficile to prevent outbreaks of CDI.

Molecular epidemiology of Clostridium difficile infection in a major chinese hospital: an underrecognized problem in Asia?

Clostridium difficile infection is almost unrecognized in mainland China. We have undertaken a study in a large Chinese teaching hospital in Changsha, Hunan, China, to identify cases of C. difficile, record patient characteristics, and define the molecular epidemiology with respect to ribotype distribution and cross-infection. Between April 2009 and February 2010, we examined fecal samples from 70 hospitalized patients with diarrhea who were receiving or had received antibiotics within the previous 6 weeks. Clinical information was collected and the samples were cultured for C. difficile retrospectively. Isolates were ribotyped, and multiple-locus variable-number tandem-repeat assay (MLVA) subtyping was performed on clusters of the same ribotype. The mean age of patients from whom C. difficile was cultured was 58 years, with only 4/21 patients aged >65 years. All patients, with a single exception, had received a third-generation cephalosporin and/or a quinolone antibiotic. Twenty-one isolates of C. difficile were recovered, and seven different ribotypes were identified, the dominant types being 017 (48%), 046 (14%), and 012 (14%). We identified two clusters of cross-infection with indistinguishable isolates of ribotype 017, with evidence of spread both within and between wards. We have identified C. difficile as a possibly significant problem, with cross-infection and a distinct ribotype distribution, in a large Chinese hospital. C. difficile may be underrecognized in China, and further epidemiological studies across the country together with the introduction of routine diagnostic testing are needed to ascertain the size of this potentially significant problem.

Hong Kong Chinese school children with elevated urine melamine levels: a prospective follow up study.

BACKGROUND: In 2008, the outbreak of kidney stones in children fed by melamine-tainted milk products in Mainland China has caused major public concern of food safety. We identified Hong Kong school children with elevated urine melamine level from a community-based school survey in 2007-08 and reviewed their clinical status in 2009. METHODS: In 2007-08, 2119 school children participated in a primary and secondary school survey in Hong Kong using a cluster sampling method. Urine aliquots from 502 subjects were assayed for melamine level. High urine melamine level was defined as urine melamine/creatinine ratio >7.1 µg/mmol. Subjects with high urine melamine level were invited for clinical evaluation in 2009 including urinalysis and ultrasound imaging of the urinary system. RESULTS: The age range of this subcohort was 6 - 20 years with 67% girls (335 female and 167 male subjects). The spot urine melamine/creatinine ratio of the 502 urine aliquots ranged from undetectable to 1467 µg/mmol (median 0.8 µg/mmol). Of these, 213 subjects had undetectable level (42%). We invited 47 (9%) subjects with high urine melamine level for re-evaluation and one subject declined. The median duration of follow-up was 23.5 months (interquartile range: 19.8 - 30.6 months). None of the 46 subjects (28% boys, mean age 13.9 ± 2.9 years) had any abnormality detected on ultrasound study of the urinary system. All subjects had stable renal function with a median urine albumin-creatinine ratio of 0.70 mg/mmol (interquartile range: 0.00 - 2.55 mg/mmol). CONCLUSIONS: Hong Kong Chinese school children with high urine melamine levels appeared to have benign clinical course in the short term although a long term follow-up study is advisable in those with persistently high urine melamine level.

Staphylococcus aureus carriage in the anterior nares of close contacts of patients with atopic dermatitis.

OBJECTIVE: To study the prevalence of Staphylococcus aureus colonization in close contacts of patients with atopic dermatitis (AD) and the influence on AD severity. DESIGN: Prospective case-control study. SETTING: Pediatric dermatology clinic in a Hong Kong university hospital. Patients We recruited 211 subjects prospectively, including 50 AD patients, 50 non-AD control subjects, 60 close contacts of AD patients, and 51 close contacts of controls. Intervention Nasal swabs and skin swabs were taken. Severity of AD was assessed using the SCORAD (Scoring Atopic Dermatitis) index. MAIN OUTCOME MEASURES: The prevalence of S aureus colonization in the close contacts of AD patients was compared with that of the close contacts of non-AD controls. Between-group differences were assessed, where appropriate, by unpaired t test or Pearson chi(2) test. Multivariate logistic regression using the forward stepwise method was performed to identify independent predictors of severe AD. A probability value of P < .05 was considered statistically significant. RESULTS: Significantly more nasal carriers of S aureus were found among the close contacts of AD patients (14 of 60 [23%]) than among the close contacts of non-AD controls (4 of 51 [8%] [P = .03]). The difference was still significant after the exclusion of the AD patients' close contacts who also had AD (24% vs 8% [P = .03]). By multivariate analysis, only skin colonization of S aureus was independently associated with severe AD (odds ratio, 17.0; 95% confidence interval, 1.60-181.1 [P = .02]). CONCLUSIONS: Anterior nares of close contacts of AD patients are reservoirs of S aureus. The presence of S aureus carriers among close contacts does not predict AD severity. Skin colonization is associated with severe AD.

High-level gentamicin resistance mediated by a Tn4001-like transposon in seven nonclonal hospital isolates of Streptococcus pasteurianus.

We report on the first occurrence of high-level gentamicin resistance (MICs > or = 512 microg/ml) in seven clinical isolates of Streptococcus pasteurianus from Hong Kong. These seven isolates were confirmed to be the species S. pasteurianus on the basis of nucleotide sequencing of the superoxide dismutase (sodA) gene. Epidemiological data as well as the results of pulse-field gel electrophoresis analysis suggested that the seven S. pasteurianus isolates did not belong to the same clone. Molecular characterization showed that they carried a chromosomal, transposon-borne resistance gene [aac(6')Ie-aph(2'')Ia] which was known to encode a bifunctional aminoglycoside-modifying enzyme. The genetic arrangement of this transposon was similar to that of Tn4001, a transposon previously recovered from Staphylococcus aureus and other gram-positive isolates. Genetic linkage with other resistance elements, such as the ermB gene for erythromycin resistance, was not evident. On the basis of these findings, we suggest that routine screening for high-level gentamicin resistance should be recommended for all clinically significant blood culture isolates. This is to avoid the inadvertent use of short-course combination therapy with penicillin and gentamicin, which may lead to the failure of treatment for endocarditis, the selection of drug-resistant Streptococcus pasteurianus and other gram-positive organisms, as well as the unnecessary usage of gentamicin, a drug with potential toxicity.

Continuous ambulatory peritoneal dialysis peritonitis: broth inoculation culture versus water lysis method.

BACKGROUND/AIM: In the setting of empiric antibiotic treatment of peritoneal-dialysis-related peritonitis complications, the speed with which a bacteriological diagnosis can be achieved is of importance. We compare the clinical performance of two culture methods to diagnose the causative microorganisms as suggested by the International Society for Peritoneal Dialysis and the United Kingdom Health Protection Agency. METHODS: We prospectively evaluated microbiological cultures of peritoneal fluid samples by the direct broth culture versus water lysis. Samples from 17 consecutive patients with dialysis-associated peritonitis were examined. RESULTS: Of the 17 dialysates cultured, 14 (82.4%) were positive by one of the two methods. The final culture results agreed in 16 of 17 specimens (94.1%). The preliminary organism identification rate by Gram staining with the broth culture method was 70.6%, which was significantly greater than 17.6% by the water lysis method (p = 0.0019). In particular, the broth culture technique demonstrated superior Gram stain performance to identify Gram-positive organisms. Among the 13 dialysate samples positive by both methods, the broth culture method detected organisms faster than the water lysis method (1.3 +/- 0.7 vs. 2.6 +/- 1.6 days, p = 0.005). CONCLUSIONS: Our results support the routine use of the broth culture technique using BacT/Alert blood culture bottles in order to facilitate early streamlining of empiric antibiotic therapy. Gram staining of sediments after centrifugation is associated with low diagnostic yield. Whether the lysis-centrifugation technique could provide additional value in case of peritonitis with a high likelihood of culture-negative results needs to be evaluated.