title: Emergence of multidrug-resistant Salmonella enterica serovar Typhi associated with a class 1 integron carrying the dfrA7 gene cassette in Nepal.
abstract: A total of 121 Salmonella enterica serovars Typhi and Paratyphi A isolated from enteric fever patients at a university hospital in Nepal between February 2004 and January 2006 were tested for their antimicrobial susceptibility. The occurrence and cassette content of integrons as well as the molecular mechanisms of resistance among the multidrug-resistant (MDR) S. Typhi were evaluated. Thirty-nine percent of the isolates were susceptible to all the antimicrobial agents tested. Seven of the S. Typhi strains were MDR. None of the 121 S. enterica isolates were resistant to ciprofloxacin, cefazolin, rifampicin or kanamycin. All MDR S. Typhi isolates contained a class 1 integron with a single cassette, dfrA7, conferring resistance to trimethoprim. Pulsed-field gel electrophoresis (PFGE) of XbaI-generated genomic restriction fragments yielded 12 different patterns. Five of the seven MDR isolates containing class 1 integrons had an identical PFGE pattern. Resistance to sulfamethoxazole, streptomycin, ampicillin, tetracycline and chloramphenicol was mediated by sul1, strA-strB, blaTEM-like, tetB and catA genes, respectively. To the best of our knowledge, this is the first report of integron-associated multidrug resistance as well as the first molecular characterisation of the mechanism of resistance of S. Typhi isolated from Nepal. This study indicates the spread of integron-associated multidrug resistance in S. Typhi in Nepal.
authors.affiliation: Department of Microbiology, School of Medicine, Kyungpook National University, 101 Dongin-dong-2 ga, Jung-gu, Daegu 700-422, South Korea.
authors.forename: Migma Dorji
authors.initials: MD
authors.lastname: Tamang
authors.forename: Jae Young
authors.initials: JY
authors.lastname: Oh
authors.forename: Sung Yong
authors.initials: SY
authors.lastname: Seol
authors.forename: Hee Young
authors.initials: HY
authors.lastname: Kang
authors.forename: Je Chul
authors.initials: JC
authors.lastname: Lee
authors.forename: Yoo Chul
authors.initials: YC
authors.lastname: Lee
authors.forename: Dong Taek
authors.initials: DT
authors.lastname: Cho
authors.forename: Jungmin
authors.initials: J
authors.lastname: Kim
mesh_terms: D016000:Cluster Analysis; D016172:DNA Fingerprinting; D004269:DNA, Bacterial / Q000235:genetics; D015252:Deoxyribonucleases, Type II Site-Specific / Q000378:metabolism; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics*; D016521:Electrophoresis, Gel, Pulsed-Field; D005798:Genes, Bacterial; D005838:Genotype; D006801:Humans; D032023:Integrons / Q000235:genetics*; D008826:Microbial Sensitivity Tests; D009390:Nepal; D010284:Paratyphoid Fever / Q000382:microbiology; D012150:Polymorphism, Restriction Fragment Length; D012482:Salmonella paratyphi A / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification; D012485:Salmonella typhi / Q000187:drug effects* / Q000235:genetics* / Q000302:isolation & purification; D014435:Typhoid Fever / Q000382:microbiology*
chemical_list: D004269:DNA, Bacterial; C025580:endodeoxyribonuclease XBAI; D015252:Deoxyribonucleases, Type II Site-Specific