This is the first report of transferable fluoroquinolone resistance due to a new qnr allele, which appeared to be linked to bla(CTX-M-14), in isolates of Salmonella Enteritidis in Hong Kong.

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Two hundred twenty isolates of Vibrio cholerae O1 and O139 collected from 1994 to 2002 in Hong Kong were analyzed by pulsed-field gel electrophoresis (PFGE). Chromosomal DNAs from all V. cholerae isolates in agarose plugs were digested with the restriction enzyme NotI, resulting in 20 to 27 bands. Sixty distinctive PFGE patterns in the range of 10 to 300 kb were noted among 213 isolates typeable by PFGE. By comparing the common PFGE patterns obtained from four well-defined outbreaks of V. cholerae O1 and O139 with those obtained from other, epidemiologically unrelated isolates during the study period, indistinguishable and similar PFGE patterns were identified, indicating their close relatedness, in agreement with the results of epidemiological investigations. Heterogeneous PFGE patterns (with four to six banding differences), however, were identified among strains that were imported from other parts of Asia, including Indonesia, India, and Pakistan. Correlations with epidemiological information further support the usefulness of PFGE as an epidemiological tool in laboratory investigations of suspected outbreaks. Standardization of PFGE methodology will allow international comparison of fingerprint patterns and will form the basis of a laboratory network for tracking V. cholerae.Serious pandemics of cholera have occurred throughout the known history of humankind. More recent data (12) from taxonomical evidence, epidemiological evidence, laboratorybased survival studies, and environmental isolations of Vibrio cholerae have provided evidence for the existence of an environmental reservoir which may be substantially influenced by climatic conditions (7). This has led to a better understanding of the epidemiological behavior of the organism. With the advent of molecular techniques, various DNA-based subtyping methods have been used to study interrelationships among V. cholerae strains at the genetic level. In particular, pulsed-field gel electrophoresis (PFGE) has been demonstrated in previous studies to be capable of analyzing relatedness (1,15,23).Hong Kong is situated in the Pearl River delta and surrounded by brackish waters. The main water supply provides a safe water source for the whole local population, but cases of cholera still occur sporadically. Since the postwar years, cholera has been a notifiable disease in Hong Kong: the law requires that cholera cases be reported to the Department of Health. The Public Health Laboratory has examined specimens collected from patients as well as food samples from case investigations and has performed bacterial subtyping by conventional methods. In this study, the PFGE technique was used to examine and analyze the genetic interrelationships in our collection of V. cholerae strains, and results were correlated with epidemiological findings for defined outbreaks that have occurred where secondary spread of the organism is limited.Through this approach, we aimed to assess how PFGE can be useful in a longitudinal study of a collection of isolates in one defined locality. We...

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