Search

Aim: Currently, there is lack of data regarding rapid antigen detection (RAD) kits to detect SARS-CoV-2 B.1.617.2 virus. Objective: The purpose of this evaluation is to assess analytical sensitivity of 12 RAD kits against SARS-CoV-2 B.1.617.2. Study design: Analytical sensitivity was determined by limit of detection (LOD). A serial tenfold dilution set from a respiratory specimen collected from a COVID-19 patient infected by SARS-CoV-2 B.1.617.2 was used. RT-PCR was used as a reference method. Results: The LOD results showed that 11 and one RAD kits were 100- and 1000-fold less sensitive than RT-PCR respectively. Conclusion: The results showed that the RAD kits evaluated in this study may be used for first-line screening of the SARS-CoV-2 B.1.617.2 variant., (© 2022 Future Medicine Ltd.)

Background: Numerous rapid antigen detection (RAD) kits for diagnosing COVID-19 patients are available in the market recently., Objective: To compare analytical sensitivity and clinical sensitivity for the three commercially available RAD kits., Study Design: Analytical sensitivity for the detection of SARS-CoV-2 virus was determined by limit of detection (LOD) using RT-PCR as a reference method. Clinical sensitivity was evaluated by using respiratory specimens collected from confirmed COVID-19 patients., Results: The LOD results showed that the three RAD kits varied from 10 2 -10 5 fold less sensitive than RT-PCR. Clinical sensitivity of RAD kits ranged from 22.9 %-71.4 % for detecting specimens from COVID-19 patients., Conclusions: Although RAD kits were less sensitive than RT-PCR, understanding the clinical characteristics of different RAD kits can guide us to obtain suitable specimens for testing. The likelihood of positive results for RAD kits will be higher., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Background: The rapid diagnosis of Coronavirus Disease 2019 (COVID-19) patients is essential to reduce the disease spread. Rapid antigen detection (RAD) tests are available, however, there is scanty data on the performance of RAD tests., Objective: To evaluate the performance of the commercially available BIOCREDIT COVID-19 Ag test and compare it with RT-PCR for detecting Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) virus. Analytical sensitivity for the detection of SARS-CoV-2 virus was determined for the RAD test using viral culture and RT-PCR as reference methods. The RAD test was further evaluated using respiratory samples collected from confirmed COVID-19 patients. The results were compared with RT-PCR test., Results: The detection limits between RAD test, viral culture and RT-PCR varied hugely. RAD was 10 3 fold less sensitive than viral culture while RAD was 10 5 fold less sensitive than RT-PCR. The RAD test detected between 11.1 % and 45.7 % of RT-PCR-positive samples from COVID-19 patients., Conclusions: This study demonstrated that the RAD test serves only as adjunct to RT-PCR test because of potential for false-negative results., Competing Interests: Declaration of Competing Interest None., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Four World Health Organization (WHO) Collaborating Centres for Reference and Research on Influenza and one WHO Collaborating Centre for the Surveillance, Epidemiology and Control of Influenza (WHO CCs) tested 10,641 viruses collected by WHO-recognized National Influenza Centres between May 2013 and May 2014 to determine 50% inhibitory concentration (IC50) data for neuraminidase inhibitors (NAIs) oseltamivir, zanamivir, peramivir and laninamivir. In addition, neuraminidase (NA) sequence data, available from the WHO CCs and from sequence databases (n=3206), were screened for amino acid substitutions associated with reduced NAI susceptibility. Ninety-five per cent of the viruses tested by the WHO CCs were from three WHO regions: Western Pacific, the Americas and Europe. Approximately 2% (n=172) showed highly reduced inhibition (HRI) against at least one of the four NAIs, commonly oseltamivir, while 0.3% (n=32) showed reduced inhibition (RI). Those showing HRI were A(H1N1)pdm09 with NA H275Y (n=169), A(H3N2) with NA E119V (n=1), B/Victoria-lineage with NA E117G (n=1) and B/Yamagata-lineage with NA H273Y (n=1); amino acid position numbering is A subtype and B type specific. Although approximately 98% of circulating viruses tested during the 2013-2014 period were sensitive to all four NAIs, a large community cluster of A(H1N1)pdm09 viruses with the NA H275Y substitution from patients with no previous exposure to antivirals was detected in Hokkaido, Japan. Significant numbers of A(H1N1)pdm09 NA H275Y viruses were also detected in China and the United States: phylogenetic analyses showed that the Chinese viruses were similar to those from Japan, while the United States viruses clustered separately from those of the Hokkaido outbreak, indicative of multiple resistance-emergence events. Consequently, global surveillance of influenza antiviral susceptibility should be continued from a public health perspective., (Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.)

Surveillance of respiratory viruses has been conducted for many years at the public health laboratory in Hong Kong. With the occurrence of pandemic influenza A (H1N1) 2009, we observed a change in the seasonality of influenza activity with a seemingly corresponding change in the activity of respiratory syncytial virus, parainfluenza virus, and adenovirus during 2009-2011. This phenomenon could most likely be explained by virus interference., (© 2012 Blackwell Publishing Ltd.)

Phylogenetic analysis of the haemagglutinin (HA) gene shows that the influenza A(H1N1)2009 viruses collected in Hong Kong clustered in two main branches characterised by the E391E and E391K amino acids. The main branch E391K evolved in two sub-branches with N142D and S202T mutations that first appeared in March and July 2010, respectively, with the latter becoming the predominant strain. These genetic variants that emerged display similar antigenic characteristics.Concurrent with genetic surveillance, laboratories should continue monitoring the circulating viruses antigenically.

To study the serologic response to the new pandemic influenza A (H1N1) 2009 virus in Hong Kong, the level of immunity was measured before and after the occurrence of the outbreak, and the titer of antibody to the pandemic influenza A (H1N1) 2009 virus in serum samples of laboratory confirmed cases. The presence of pre-outbreak pandemic influenza A (H1N1) 2009 virus antibodies in 37% of individuals older than >65 years suggested previous exposures to heterologous virus strains may have elicited cross-reacting antibody. Following large outbreaks of pandemic influenza A 2009 virus that peaked in September 2009, there is a change in immunity level in various age groups consistent with the attack rates among population in Hong Kong. Among individuals with mild clinical presentation, the antibody response to pandemic influenza A (H1N1) 2009 virus was stronger in those individuals aged ≤ 24 years but took more time to reach a titer of 40 when compared with those aged >24 years; however, the antibody level declined slower among individuals aged ≤ 24 years. Regardless of age, the antibody response rose rapidly and reached much higher titer among individuals with severe clinical presentation. Further study is required to collect additional data on antibody persistence and determine how much protection is conferred by previous exposure to seasonal influenza A (H1N1) viruses., (© 2010 Wiley-Liss, Inc.)

Background: To diagnose influenza A(H1N1)v virus infection, accurate and rapid detection are important. However, there is scanty data on the performance of various laboratory diagnostics., Objective: To compare the performance of rapid antigen test (RAT), viral culture and RT-PCR for the detection of influenza A(H1N1)v virus and to correlate their performance with the time after symptom onset and viral load., Study Design: From May 1, 2009 to June 25, 2009, respiratory samples were collected from 5740 individuals suspected of having influenza A(H1N1)v infection. The performance of viral culture and RT-PCR were investigated and correlated with the time after symptom onset. The sensitivity of RAT ESPLINE influenza A & B-N (Fujirebio Inc, Tokyo) was evaluated using a subset of 60 samples from patients diagnosed as having influenza A(H1N1)v infection., Results: Using respiratory samples from 587 patients diagnosed with influenza A(H1N1)v infection, comparison of laboratory diagnostics showed viral culture and RT-PCR gave comparable results with overall sensitivity of 93.9% and 98.1%, respectively. For RAT, when testing a subset of 60 samples collected < or =3 days following symptom onset, the sensitivity was 62%., Conclusions: Although viral shedding is prolonged and of higher titre in influenza A(H1N1)v infection, RAT showed a low sensitivity of 62% among patients presenting < or =3 days after symptom onset. Viral culture showed comparable performance with RT-PCR and with sensitivity better than that documented for seasonal influenza.

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.

In a population-based study, we use ICD-9-CM codes to estimate the hospitalization rates for pneumococcal disease among young children in Hong Kong, 2000-2005 and the preventable burden using several outcome indicators. For children aged

Objective: To determine the prevalence and molecular epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) strains among residents in residential care homes for the elderly in Hong Kong., Design: Cross-sectional and descriptive study., Participants: A total of 949 residents in 13 residential care homes for elderly persons in Hong Kong in January 2005., Methods: MRSA colonization was assessed by culture of swab specimens from anterior nares and active skin lesions. Characteristics of residents were obtained by a standard questionnaire. All MRSA isolates were analyzed by polymerase chain reaction for their staphylococcal cassette chromosome (SCC) mec content and were typed by pulsed-field gel electrophoresis (PFGE) and multilocus sequencing., Results: MRSA colonization was detected in 27 residents (2.8%). No MRSA was found in 2 facilities. The rate of MRSA carriage in the other 11 facilities ranged from 1.9% to 4.2%. In univariate analysis, functional immobility (odds ratio [OR], 1.4), history of hospital admission (OR, 2.3), and the use of nebulized medication (OR, 5.4) were significantly associated with MRSA colonization. The isolates had 11 unique antibiograms, with 14 isolates susceptible to all but 1 or 2 of the non- beta -lactam antimicrobial agents tested. The isolates exhibited SCCmec types I (1 isolate), II (2 isolates), III (1 isolate), IV/IVA (10 isolates), and V (13 isolates). No isolates had the Panton-Valentine leukocidin genes. PFGE analysis clustered all except 1 isolate into 7 PFGE types, designated HKU10 to HKU70. Between 1 and 4 unique PFGE types were found in the individual residential care facilities., Conclusion: This study documented the emergence of SCCmec types IV and V among genetically diverse MRSA strains in residential care homes for elderly persons in Hong Kong.

This study evaluated the clinical and epidemiologic features of individuals with community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) in Hong Kong from January 2004 through December 2005. Twenty-four episodes of skin and soft tissue infections and 1 episode of meningitis due to CA-MRSA were identified. CA-MRSA infections or carriage was found in 6 (13%) of 46 household contacts. A total of 29 isolates were analyzed by the Staphylococcus cassette chromosome mec (SCCmec) typing, pulsed-field gel electrophoresis (PFGE), and multilocus sequence typing. In addition, polymerase chain reaction detection of the genes encoding Panton-Valentine leukocidin was also carried out. It was observed that 24 had SCCmec IV/IVA and 5 had SCCmec V, and 23 were pvl positive. PFGE analysis clustered all except 1 isolate into 3 pulsed-field types (PFTs), HKU100 through HKU300. The HKU100 isolates had genotype ST30-IV identical to the Southwest Pacific clone. The HKU200 isolates belonged to ST59-V and were multiresistant, including an ermB-mediated macrolide resistance trait, which is characteristic of the predominant CA-MRSA clone in Taiwan. The HKU300 isolates had unique features (ST8, Panton-Valentine leukocidin negative, and SCCmec IVA) typical of CA-MRSA in Japan. In conclusion, CA-MRSA has a propensity to spread within families. Our findings showed that CA-MRSA strains in Hong Kong have diverse genetic backgrounds.

A study was conducted to evaluate the occurrence of extended-spectrum beta-lactamases (ESBLs)-producing Escherichia coli from fecal samples of healthy food animals in Hong Kong. Rectal or cloacal swabs were obtained from cattle, pigs, chicken, ducks, geese, and pigeons in slaughterhouses or wholesale markets over a 5- month period in 2002. Antibiotic-containing medium was used for selective isolation of potentially ESBL-producing E. coli. Of 734 samples analyzed, six (2%) from pigs, three (3.1%) from cattle, and one (3%) from pigeons had E. coli strains with the ESBL phenotype. The ESBL content for the 10 isolates include CTXM- 3 (n = 4), CTX-M-13 (n = 3), CTX-M-14 (n = 2), and CTX-M-24 (n = 1). In five isolates, the bla (CTX-M) gene was encoded on transferable plasmids (60 or 90 kb), and the gene was found to transfer to E. coli (J53 or JP995) with frequencies of 10(7) to 10(3) per donor cells. The ten isolates had five distinct pulsotypes with some clonal spread. However, the isolates from the different kinds of animals were not clonally related. These findings imply that bacteria of animal origins may serve as reservoirs of some ESBL genes.

This paper reports the first case of Haemophilus quentini bacteremia with reduced susceptibility to levofloxacin and resistance to nalidixic acid identified by 16S rRNA sequencing. There was an S 84 L substitution in gyrA and an S 84 I substitution in par C. The isolate had co-resistance to ampicillin (beta-lactamase positive) and tetracycline mediated by the tet(B) gene.

Objectives: A study was conducted to evaluate the occurrence and characterization of extended-spectrum beta-lactamases (ESBLs) among blood isolates of Proteus mirabilis collected over a 4 year period in Hong Kong., Methods: Production of ESBLs among 99 consecutive and non-duplicate isolates was evaluated by the double-disc synergy test. The ESBLs were characterized by isoelectric focusing and PCR sequencing using specific primers. The epidemiological relationship of the isolates was studied by the Dienes test and PFGE., Results: ESBLs were identified in 13 isolates, from none in 1999-2000 and up to 18.5% (5/27) in 2001 and 25.8% (8/31) in 2002. The ESBL-producing isolates were more resistant to ceftriaxone than to ceftazidime, and were more likely than non-ESBL-producers to have resistance to ciprofloxacin (76.9% versus 14%) and gentamicin (38.5% versus 9.3%). The ESBL content included CTX-M-13 (n=8), CTX-M-14 (n=3), SHV-5 (n=2), TEM-11 (n=1), and an unidentified ESBL with a pI of 7.5. The Dienes test revealed that the genetic background in the 99 isolates was highly heterogeneous, with 54 distinct types among 92 isolates and seven were non-typeable. Among the 13 ESBL-producing isolates, five different backgrounds, including one cluster (Dienes-pulsotype A) with nine isolates, were identified by both Dienes test and PFGE, thus suggesting both clonal and multi-clonal spread of the CTX-M enzymes., Conclusions: Our findings indicate the emergence of CTX-M enzymes among P. mirabilis in Hong Kong. More ESBL screening of this species is required to improve their recognition.

Objectives: A total of 139 consecutive and non-duplicate bloodstream isolates of Enterobacter spp. collected from inpatients in Hong Kong during 2000-2002 were studied for production of extended-spectrum beta-lactamases (ESBLs)., Methods: All isolates were evaluated by the modified double-disc synergy test (m-DDST), the combined disc method (CDM) and the three-dimensional (3D) test. The m-DDST and CDM were modified by the use of cefepime discs. beta-Lactamases were characterized by isoelectric focusing and PCR sequencing using specific primers., Results: ESBLs were identified in nine isolates (overall 6.5%), including seven of 39 (17.9%) Enterobacter hormaechei, one of 27 (3.7%) Enterobacter aerogenes and the only Enterobacter intermedius strain. The E. intermedius strain was positive only in the 3D test but not in the other two tests. The other eight strains were positive in all three tests. No ESBL was detected in the other species, including non-hormaechei members of the Enterobacter cloacae complex (n=61), Enterobacter agglomerans (n=7), Enterobacter gergoviae (n=4) and Enterobacter sakazakii (n=1). The ESBL content included five different CTX-M enzymes (CTX-M-9, CTX-M-13, CTX-M-14, CTX-M-24 and a novel CTX-M-2-like beta-lactamase), SHV-12 (n=2) and unidentifiable ESBLs with a pI of 7.7 or 7.9 in two strains. The seven ESBL-producing E. hormaechei were genotyped by pulsed-field gel electrophoresis and were found to be unrelated to each other. In three of the CTX-M-producing strains, ISEcp1-like elements, including promoters for the beta-lactamase gene, were found., Conclusions: Our data underscore the diversity of CTX-M enzymes among Enterobacter spp. in Hong Kong.

Among 563 strains of Haemophilus influenzae from young children in Hong Kong, 5 (0.9%) had decreased susceptibility to quinolones. The five strains had a Ser-84-Lys or Asp-88-Asn substitution in GyrA. Pulsed-field gel electrophoresis showed that the isolates are genetically diverse.