High Prevalence and Frequent Acquisition of Clostridium difficile Ribotype 002 Among Nursing Home Residents in Hong Kong.

OBJECTIVETo determine the incidence and risk factors associated with Clostridium difficile colonization among residents of nursing homes and to identify the ribotypes of circulating C. difficile strains.DESIGNA prospective cohort study with a follow-up duration of 22 months.SETTINGNursing homes.PARTICIPANTSOf the 375 residents in 8 nursing homes, 300 residents (80.0%) participated in the study. A further prospective study of 4 nursing homes involving 141 residents with a minimum of 90 days of follow-up was also performed.METHODSBaseline and 90-day stool cultures were obtained; additional stool cultures were obtained for residents who had been discharged from hospitals. Polymerase chain reaction (PCR) ribotyping and slpA typing were performed for all C. difficile strains isolated.RESULTSToxigenic C. difficile was isolated in 30 residents (10%) at baseline, and 9 residents (7.3%) had acquired toxigenic C. difficile in the nursing homes. The presence of nasogastric tube was an independent risk factor (adjusted odds ratio, 8.59; 95% confidence interval, 1.18-62.53; P=.034) for C. difficile colonization. The Kaplan-Meier estimate of median carriage duration was 13 weeks. The C. difficile ribotypes most commonly identified were 002 (40.8%), 014 (16.9%), 029 (9.9%), and 053 (8.5%).CONCLUSIONSThe high incidence of C. difficile colonization and the overrepresentation of C. difficile ribotype 002 confirmed the contribution of nursing home residents to C. difficile transmission across the continuum of care. An infection control program is needed in long-term care.Infect Control Hosp Epidemiol 2018;782-787.

Influenza Vaccine Effectiveness Against Influenza A(H3N2) Hospitalizations in Children in Hong Kong in a Prolonged Season, 2016/2017.

Background: Influenza A(H3N2) viruses circulated for 12 consecutive months in Hong Kong in 2016-2017, peaking in late June and July 2017. The objective of our study was to estimate the effectiveness of influenza vaccination in preventing hospitalizations in children in Hong Kong. Methods: We conducted a test-negative study between 1 September 2016 and 31 August 2017, enrolling children 6 months to 17 years of age hospitalized for an acute respiratory infection. Influenza was diagnosed by PCR on nasopharyngeal aspirates. Results: We enrolled 5514 children, including 3608 children 6 months to 2 years, 1600 children 3-5 years, and 1206 children 6-17 years of age. Influenza-associated hospitalizations occurred throughout the study year but time of vaccination of these children was also wide spread, from September 2016 to May 2017. Influenza vaccine effectiveness (VE) was 39.7% (95% confidence interval [CI], 14.7%-57.3%) against laboratory-confirmed influenza A(H3N2). In analyses stratified by time since vaccination, the VE against influenza A(H3N2) was 52.8% (95% CI, 17.1%-73.2%) within 3 months of vaccination, and 31.2% (95% CI, -6.6% to 55.6%) 4-6 months after vaccination. Conclusions: Influenza vaccination was effective in preventing hospitalizations in children in Hong Kong.

Corynebacterium kroppenstedtii Is an Emerging Cause of Mastitis Especially in Patients With Psychiatric Illness on Antipsychotic Medication.

This retrospective study of patients with Corynebacterium kroppenstedtii infections revealed a predominance of mastitis and a potential association with psychiatric illnesses. At least one third of our patients with C kroppenstedtii mastitis had psychiatric illness, and >92% received antipsychotic medications. Drug-induced hyperprolactinemia may be an important modifiable risk factor in these patients.

Interim estimates of the effectiveness of influenza vaccination against influenza-associated hospitalization in children in Hong Kong, 2015-16.

From 1 September 2015 through 31 January 2016, we enrolled 2068 children 6 months to 17 years of age admitted to hospital with a febrile acute respiratory infection in our test-negative study. Information on receipt of 2015-16 northern hemisphere inactivated influenza vaccination was elicited from parents or legal guardians. Using conditional logistic regression adjusting for age and matching on calendar time, we estimated influenza vaccine effectiveness against hospitalization with influenza A or B to be 79.2% (95% confidence interval: 42.0%-92.4%). Annual influenza vaccination should be more widely used in children in Hong Kong.

Clinical features and molecular epidemiology of plasmid-mediated DHA-type AmpC ß-lactamase-producing Klebsiella pneumoniae blood culture isolates, Hong Kong.

Knowledge of risk factors and clinical characteristics of bacteraemia caused by plasmid-mediated AmpC ß-lactamase (pAmpC)-producing Klebsiella pneumoniae (pAmpC-Kp) is not well described. This was a retrospective cohort study of patients with K. pneumoniae bacteraemia in three Hong Kong regional hospitals. Demographic and clinical data were retrieved from medical records. Pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) were performed for molecular epidemiology. A total of 109 patients were included, divided into four groups: bacteraemia due to K. pneumoniae with (i) DHA-type pAmpC (n=23), (ii) extended-spectrum ß-lactamase (ESBL) (n=37), (iii) DHA-type pAmpC+ESBL (n=26) and (iv) controls (n=23). Nursing home residence was independently associated with pAmpC-Kp bacteraemia compared with ESBL-Kp bacteraemia [adjusted odds ratio (aOR)=7.13, 95% confidence interval (CI) 1.36-37.54] and controls (aOR=41.47, 95% CI 4.55-377.75). Compared with controls, patients with pAmpC-Kp bacteraemia also suffered from more severe illness [median Acute Physiology and Chronic Health Evaluation (APACHE) II scores 16 and 25, respectively; P=0.006]. Importantly, the pAmpC group received discordant empirical antimicrobial therapy more frequently (OR=24.00, 95% CI 5.01-114.97), resulting in higher 7-day mortality (OR=20.17, 95% CI 2.32-175.67) and 30-day mortality (OR 4.68, 95% CI 1.29-16.98). PFGE detected six pulsotypes, corresponding to the predominant sequence type 11. Severity of illness and mortality of patients with bacteraemia caused by pAmpC-Kp were high. Patients who are nursing home residents presenting nosocomial sepsis should be treated with broad-spectrum antimicrobials.

Prevalence of aminoglycoside modifying enzyme and 16S ribosomal RNA methylase genes among aminoglycoside-resistant Escherichia coli isolates.

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.

High prevalence of Escherichia coli sequence type 131 among antimicrobial-resistant E. coli isolates from geriatric patients.

Previous work on the subclones within Escherichia coli ST131 predominantly involved isolates from Western countries. This study assessed the prevalence and antimicrobial resistance attributed to this clonal group. A total of 340 consecutive, non-duplicated urinary E. coli isolates originating from four clinical laboratories in Hong Kong in 2013 were tested. ST131 prevalence among the total isolates was 18.5 % (63/340) and was higher among inpatient isolates (23.0 %) than outpatient isolates (11.8 %, P<0.001), and higher among isolates from patients aged ≥65 years than from patients aged 18-50 years and 51-64 years (25.4 vs 3.4 and 4.0 %, respectively, P<0.001). Of the 63 ST131 isolates, 43 (68.3 %) isolates belonged to the H30 subclone, whereas the remaining isolates belonged to H41 (n = 17), H54 (n = 2) and H22 (n = 1). All H30 isolates were ciprofloxacin-resistant, of which 18.6 % (8/43) belonged to the H30-Rx subclone. Twenty-six (41.3 %) ST131 isolates were ESBL-producers, of which 19 had blaCTX-M-14 (12 non-H30-Rx, two H30-Rx and five H41), six had blaCTX-M-15 (five non-H30-Rx and one H30-Rx) and one was blaCTX-M-negative (H30). In conclusion, ST131 accounts for a large share of the antimicrobial-resistant E. coli isolates from geriatric patients. Unlike previous reports, ESBL-producing ST131 strains mainly belonged to non-H30-Rx rather than the H30-Rx subclone, with blaCTX-M-14 as the dominant enzyme type.

Prevalence and predictive factors of harboring fluoroquinolone-resistant and extended-spectrum ß-lactamase-producing rectal flora in Hong Kong Chinese men undergoing transrectal ultrasound-guided prostate biopsy.

OBJECTIVE: To study the prevalence of fluoroquinolone-resistant (FQ-resistant) and extended-spectrum ß-lactamase-producing (ESBL-producing) bacteria in the rectums of patients undergoing transrectal ultrasound-guided prostate biopsy (TRUS-Bx), identifying predictive factors for such carriage and to correlate with the microbiology of those who developed postbiopsy infection (PBI). METHODS: A total of 371 men undergoing TRUS-Bx were prospectively enrolled from August 2011 to March 2012. Rectal swab was obtained before antimicrobial prophylaxis on the day of biopsy and grown in selective media for resistant bacteria. Standard FQ prophylaxis was used without guidance from rectal swab results. Univariate and multivariate analyses were performed to identify predictive factors of either FQ-resistant or ESBL-producing bacteria carriage. RESULTS: A total of 199 of 371 patients (53.6%) carried antimicrobial-resistant rectal flora, with 150 (40.4%) and 152 (41.0%) patients having FQ-resistant and ESBL-producing bacteria, respectively. Diabetes mellitus (odds ratio, 2.075; P = .028) and the use of antimicrobials within the prior 5 years (odds ratio, 1.550; P = .047) were independent predictors of rectal carriage of such flora. PBI occurred in 9 patients, of which 7 harbored prebiopsy antimicrobial-resistant bacteria, which completely matched the microbiological data collected during the patients' PBI episodes. CONCLUSION: A high prevalence of FQ-resistant and ESBL-producing rectal flora in Chinese men undergoing TRUS-Bx was found. Diabetes mellitus and prior antimicrobial use within 5 years were significant predictors for resistant bacterial carriage. Despite the high-resistant bacteria prevalence, PBI rate remained low. A targeted approach of antimicrobial prophylaxis using prebiopsy culture swab in areas with high prevalence of resistant bacteria should be further investigated.

Application of a target enrichment-based next-generation sequencing protocol for identification and sequence-based prediction of pneumococcal serotypes.

BACKGROUND: The use of whole-genome sequencing in microbiology at a diagnostic level, although feasible, is still limited by the expenses associated and by the complex bioinformatics pipelines in data analyses. We describe the use of target enrichment-based next-generation sequencing for pneumococcal identification and serotyping as applied to the polysaccharide 23 valent vaccine serotypes as an affordable alternative to whole genome sequencing. RESULTS: Correct identification of Streptococcus pneumoniae and prediction of common vaccine serotypes: 12 to serotype level and the rest to serogroup levels were achieved for all serotypes with >500 reads mapped against serotypes sequences. A proportion-based criterion also enabled the identification of two serotypes present in the same sample, thus indicating the possibility of using this method in detecting co-colonizing serotypes. The results obtained were comparable to or an improvement on the currently existing molecular serotyping methods for S. pneumoniae in relation to the polysaccharide vaccine serotypes. CONCLUSION: We propose that this method has the potential to become an affordable and adaptable alternative to whole-genome sequencing for pneumococcal identification and serotyping.

A cost-effective approach for detection of toxigenic Clostridium difficile: toxigenic culture using ChromID Clostridium difficile agar.

We evaluated the performance and the cost of toxigenic culture using a commercial chromogenic medium (CDIF) for 538 stool specimens. Compared with real-time PCR, this method was found to detect an additional 9% of positive specimens and result in 61% reduction in material costs, with a trade-off increase in turnaround time of 1 day.

Prevalence, prediction, and clonality of methicillin-resistant Staphylococcus aureus carriage at admission to medical units in Hong Kong, China.

OBJECTIVE: To determine the prevalence, risk factors, and molecular epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) colonization at the time of admission to acute medical units and to develop a cost-effective screening strategy. METHODS: Nasal and groin screening cultures were performed for patients at admission to 15 acute medical units in all 7 catchment regions in Hong Kong. All MRSA isolates were subjected to spa typing. RESULTS: The overall carriage rate of MRSA was 14.3% (95% confidence interval [CI], 13.5-15.1). MRSA history within the past 12 months (adjusted odds ratio [OR], 4.60 [95% CI, 3.28-6.44]), old age home residence (adjusted OR, 3.32 [95% CI, 2.78-3.98]), and bed-bound state (adjusted OR, 2.19 [95% CI, 1.75-2.74]) were risk factors selected as MRSA screening criteria that provided reasonable sensitivity (67.4%) and specificity (81.8%), with an affordable burden (25.2%). spa typing showed that 89.5% (848/948) of the isolates were clustered into the 4 spa clonal complexes (CCs): spa CC1081, spa CC032, spa CC002, and spa CC4677. Patients colonized with MRSA spa types t1081 (OR, 1.77 [95% CI, 1.49-2.09]) and t4677 (OR, 3.09 [95% CI, 1.54-6.02]) were more likely to be old age home residents. CONCLUSIONS: MRSA carriage at admission to acute medical units was prevalent in Hong Kong. Our results suggest that targeted screening is a pragmatic approach to increase the detection of the MRSA reservoir. Molecular typing suggests that old age homes are epicenters in amplifying the MRSA burden in acute hospitals. Enhancement of infection control measures in old age homes is important for the control of MRSA in hospitals.

Clonality and antimicrobial susceptibility of Staphylococcus aureus and methicillin-resistant S. aureus isolates from food animals and other animals.

Out of 3,081 animals studied, 24.9% of pigs, 4.7% of chickens, 6.3% of dogs, 10.5% of cats, and 7.1% of rodents were Staphylococcus aureus positive. Prevalence of methicillin-resistant S. aureus (MRSA) was high in pigs (animals, 21.3%; batches, 46.5%), with all MRSA isolates and most methicillin-sensitive S. aureus isolates belonging to clonal complex 9 (CC9) and being multidrug resistant. The predominant S. aureus CCs among dog and cat isolates were similar. Among rodent isolates, CC398 predominated, with spa t034 the most frequent spa type detected.

Identification and characterization of a novel incompatibility group X3 plasmid carrying bla NDM-1 in Enterobacteriaceae isolates with epidemiological links to multiple geographical areas in China.

The New Delhi metallo-ß-lactamase (NDM-1) is one of the most important resistance traits in Enterobacteriaceae. We characterized nine bla NDM-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 bla NDM-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 bla NDM-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 bla NDM-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 bla NDM-1 containing module within the two IS elements were identical to those previously described for bla NDM-1-positive Tn125 in the plasmids or chromosome of Acinetobacter isolates. In summary, this is the first description of IncX3 plasmids carrying bla NDM-1. The findings indicate the worrisome involvement of an epidemic plasmid in the dissemination of NDM-1 in China.

Effect of clinical and virological parameters on the level of neutralizing antibody against pandemic influenza A virus H1N1 2009.

BACKGROUND: 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. METHODS: 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. RESULTS: 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). CONCLUSIONS: 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.

Viral load in patients infected with pandemic H1N1 2009 influenza A virus.

Viral shedding profile of infections caused by the pandemic H1N1 2009 influenza A virus has not been reported. The aim of this study was to determine the viral load in different body sites. Viral loads of pandemic H1N1 virus in respiratory specimens, stool, urine, and serum were determined by quantitative reverse transcriptase-polymerase chain reaction (RT-PCR). Respiratory specimens from patients with seasonal influenza were used as historical controls. Initial pre-treatment viral load were compared between these two groups. Serial respiratory specimens from patients with pandemic H1N1 virus infection were obtained for analysis of viral dynamics. Twenty-two pandemic H1N1 cases and 44 seasonal influenza historical controls were included. The mean initial viral load before oseltamivir therapy was 1.84 x 10(8) copies/ml for pandemic H1N1 virus compared with 3.28 x 10(8) copies/ml in seasonal influenza historical controls (P = 0.085). Among patients with pandemic H1N1 virus infection, peak viral load occurred on the day of onset of symptoms, and declined gradually afterwards, with no virus being detectable in respiratory specimens by RT-PCR 8 days and by culture 5 days after the onset of symptoms respectively, except in one patient. Pandemic H1N1 virus was detected in stool and in urine from 4/9 and 1/14 patients, respectively. Viral culture was also positive from the stool sample with the highest viral load. Younger age was associated with prolonged shedding in the respiratory tract and higher viral load in the stool. Data from this quantitative analysis of viral shedding may have implications for formulating infection control measures.

Identification of novel porcine and bovine parvoviruses closely related to human parvovirus 4.

Human parvovirus 4 (PARV4), a recently discovered parvovirus found exclusively in human plasma and liver tissue, was considered phylogenetically distinct from other parvoviruses. Here, we report the discovery of two novel parvoviruses closely related to PARV4, porcine hokovirus (PHoV) and bovine hokovirus (BHoV), from porcine and bovine samples in Hong Kong. Their nearly full-length sequences were also analysed. PARV4-like viruses were detected by PCR among 44.4 % (148/333) of porcine samples (including lymph nodes, liver, serum, nasopharyngeal and faecal samples), 13 % (4/32) of bovine spleen samples and 2 % (7/362) of human serum samples that were sent for human immunodeficiency virus and hepatitis C virus antibody tests. Three distinct parvoviruses were identified, including two novel parvoviruses, PHoV and BHoV, from porcine and bovine samples and PARV4 from humans, respectively. Analysis of genome sequences from seven PHoV strains, from three BHoV strains and from one PARV4 strain showed that the two animal parvoviruses were most similar to PARV4 with 61.5-63 % nt identities and, together with PARV4 (HHoV), formed a distinct cluster within the family Parvoviridae. The three parvoviruses also differed from other parvoviruses by their relatively large predicted VP1 protein and the presence of a small unique conserved putative protein. Based on these results, we propose a separate genus, Hokovirus, to describe these three parvoviruses. The co-detection of porcine reproductive and respiratory syndrome virus, the agent associated with the recent 'high fever' disease outbreaks in pigs in China, from our porcine samples warrants further investigation.

Risk factors associated with life-threatening rickettsial infections.

We retrospectively analyzed 92 cases of severe rickettsial infections in patients (median age = 49 years, 57% male, 37.0% with scrub typhus) in Hong Kong. Immunofluorescence assay was used for diagnostic confirmation. Identification of > or = 1 diagnostic sign (exposure history, rash, or eschar) was possible in 94.6% of the cases. Multivariate analysis suggested that pulmonary infiltrates (odds ratio [OR] = 25.2, 95% confidence interval [CI] = 3.9-160.9, P = 0.001) and leukocytosis (OR = 1.3, 95% CI = 1.0-1.5 per unit increase, P = 0.033) were independent predictors of admission to an intensive care unit (14.1%). Delayed administration of doxycycline was independently associated with major organ dysfunction (23.9%; oxygen desaturation, renal failure, severe jaundice, encephalopathy, cardiac failure) (OR = 1.2, 95% CI = 1.0-1.5 per day delay, P = 0.046; adjusted for age and rickettsia biogroup) and prolonged hospitalization > 10 days (25%) (OR = 1.4, 95% CI = 1.1-1.9 per day delay, P = 0.014). Treatment with fluoroquinolone/clarithromycin did not correlate with clinical outcomes (P > 0.05). Early empirical doxycycline therapy should be considered if clinico-epidemiologic signs of rickettsial infections are present.