We report detection of severe acute respiratory syndrome coronavirus 2 Omicron variant (B.1.1.529) in an asymptomatic, fully vaccinated traveler in a quarantine hotel in Hong Kong, China. The Omicron variant was also detected in a fully vaccinated traveler staying in a room across the corridor from the index patient, suggesting transmission despite strict quarantine precautions.

A new strategy known as multiplex PCR amplimer conformation was developed for detection of mutation in the gyrA gene of 138 clinical isolates of Mycobacterium tuberculosis. The method generated a single-stranded and heteroduplex DNA banding pattern of multiplex PCR amplimers of the region of interest that was extremely sensitive to specific mutations, thus enabling much more sensitive and reliable mutation analysis compared to the standard single-stranded conformation polymorphism technique. The genetic profiles of the gyrA gene of the 138 isolates as detected by MPAC were confirmed by nucleotide sequencing and were found to correlate strongly with the in vitro susceptibilities of the mutant strains to six fluoroquinolones (ofloxacin, levofloxacin, sparfloxacin, moxifloxacin, gatifloxacin, and sitafloxacin). All 32 isolates that contained gyrA mutations exhibited cross-resistance to the six fluoroquinolones (ofloxacin MIC for 90% of strains > 16 mg/liter), although moxifloxacin, gatifloxacin, and sitafloxacin (MIC for 90% of strains < 4 mg/liter) were apparently more active than ofloxacin, levofloxacin, and sparfloxacin (MIC for 90% of strains > 16 mg/liter). All gyrA mutations were clustered in codons 90, 91, and 94, and aspartic acid 94 was most frequently mutated. Twenty-three isolates without gyrA mutations were also found to exhibit reduced susceptibility to ofloxacin (MIC for 90% of strains ‫؍‬ 4 mg/liter), but largely remained susceptible to other drugs (MIC for 90% of strains < 1 mg/liter). Another 83 isolates without mutations were fully susceptible to all six fluoroquinolones (ofloxacin MIC for 90% of strains ‫؍‬ 1 mg/liter). In conclusion, high-level phenotypic resistance to fluoroquinolones among M. tuberculosis clinical isolates, which appears to be predominantly due to gyrA mutations, may be readily detected by genotyping techniques such as multiplex PCR amplimer conformation.Fluoroquinolones have antimycobacterial activities that possibly contribute a pivotal role in the second-line drug regimens used in the treatment of multidrug-resistant tuberculosis (32). However, in some communities, the resistance rates of Mycobacterium tuberculosis to these agents are surging (6, 9). To date, the genetic basis of this phenomenon has been attributed predominantly to mutations in the quinolone resistance-determining region of the gyrA gene (1,10,28,31).It would be of great relevance not only to study the genetic mutations responsible for fluoroquinolone resistance, but also to establish, as far as possible, their correlation with the resistance phenotypes of clinical isolates of M. tuberculosis. Such information facilitates rapid determination of the fluoroquinolone susceptibility status of the isolates and helps improve the clinical utility of these drugs in the settings of multidrug-resistant tuberculosis, as in cases involving streptomycin-and rifampin-resistant strains of M. tuberculosis (19,21). Hence, the major objective of this study was to identify the gyrA mutation(s), if any, in 138 clinical isolate...

Respiratory tract infections can be caused by a heterogeneous group of viruses and bacteria that produce similar clinical presentations. Specific diagnosis therefore relies on laboratory investigation. This study developed and evaluated five groups of multiplex nested PCR assays that could simultaneously detect 21 different respiratory pathogens: influenza A virus (H1N1, H3N2, and H5N1); influenza B virus; parainfluenza virus types 1, 2, 3, 4a, and 4b; respiratory syncytial virus A and B; human rhinoviruses; human enteroviruses; human coronaviruses OC43 and 229E; severe acute respiratory syndrome coronavirus; human metapneumoviruses; Mycoplasma pneumoniae; Chlamydophila pneumoniae; Legionella pneumophila; and adenoviruses (A to F). These multiplex nested PCRs adopted fast PCR technology. The high speed of fast PCR (within 35 min) greatly improved the efficiency of these assays. The results show that these multiplex nested PCR assays are specific and more sensitive (100-to 1,000-fold) than conventional methods. Among the 303 clinical specimens tested, the multiplex nested PCR achieved an overall positive rate of 48.5% (95% confidence interval [CI], 42.9 to 54.1%), which was significantly higher than that of virus isolation (20.1% [95% CI, 15.6 to 24.6%]) and that of direct detection by immunofluorescence assay (13.5% [95% CI, 9.7 to 17.4%]). The improved sensitivity was partly due to the higher sensitivity of multiplex nested PCR than that of conventional methods in detecting cultivatable viruses. Moreover, the ability of the multiplex nested PCR to detect noncultivatable viruses, particularly rhinoviruses, coronavirus OC43, and metapneumoviruses, contributed a major gain (15.6%) in the overall positive rate. In conclusion, rapid multiplex nested PCR assays can improve the diagnostic yield for respiratory infections to allow prompt interventive actions to be taken.

Consensus primers targeting human papillomaviruses (HPVs) have biases in sensitivity toward certain HPV types. We applied 3 primer sets (GP51/61, MY09/11, PGMY09/11) in parallel on 120 Chinese cervical cancer specimens. GP51/61 exhibited a poor sensitivity for HPV52, for which the prevalence among squamous cell cervical cancer was underestimated from 14.6% to 0%. The fact that HPV52 should rank second in prevalence among squamous cell cervical carcinoma in Hong Kong could be missed if GP51/61, a worldwide commonly used primer set, was selected for HPV detection. Biases in HPV type-specific sensitivity may result in misprioritization of vaccine candidates. ' 2005 Wiley-Liss, Inc.Key words: human papillomavirus; detection; genotype; vaccine; Chinese; Hong Kong; PCR Cervical cancer is the second most common cancer in women worldwide. Strong and consistent evidence accumulated over the past 2 decades confirms the aetiologic role of human papillomaviruses (HPVs) and provides a strong impetus for developing HPV vaccines to prevent cervical cancer. More than 100 HPV types have been identified, and at least 30 have been found in cervical cancers. 1 Given the diversity of HPV types and the largely typespecific immunity after natural infections, 2-4 it is important to delineate the prevalence of different HPV types found in cervical cancers so as to guide the selection of vaccine candidates. Most studies on HPV have employed consensus primers with an intention to cover a broad spectrum of HPV types. With the more than 10% sequence variation between HPV types, biases in sensitivity of a given primer set toward certain types could happen. In our study, we examined the influence of detection methods on assessing the prevalence of HPVs and thus their priority as cervical cancer vaccine candidates. Material and methodsA total of 120 cervical cancer specimens (105 fresh frozen and 15 paraffin embedded; 89 squamous cell carcinoma, 26 adenocarcinoma, 4 adenosquamous carcinoma and 1 lymphoepitheliod carcinoma) collected from Hong Kong Chinese aged 26-84 years (mean 55 years; SD 13.9) were examined. Total DNA was extracted by the QIAamp DNA mini kit (QIAGEN, Hilden, Germany) and with the quality of extracted preparations confirmed by beta-globin PCR. 5 The clinical materials were collected with a written informed consent. Our study was approved by the local institutional ethics committee, and the human experimentation guidelines of the local institute were followed in the conduct of our study.HPV detection and typing was accomplished by 3 different methods in parallel. In the first method, HPV DNA was amplified by the GP51/61 primers that target an approx. 150 bp fragment of the L1 region. 5,6 The HPV type was identified by direct sequencing of PCR amplicons. In the second method, the MY09/ 11 primers that target an approx. 450 bp fragment of the L1 region was used for PCR. 7,8 HPV type was identified by restriction fragment length polymorphisms (RFLPs) using endonucleases RsaI and DdeI as previously described. 8 Ambiguous RFLPs w...