Emerging fluoroquinolone and macrolide resistance of Campylobacter jejuni and Campylobacter coli isolates and their serotypes in Thai children from 1991 to 2000.

This study investigated fluoroquinolone, macrolide resistances and serotype distributions among Campylobacter jejuni and Campylobacter coli isolated from children in Bangkok and rural settings during 1991-2000. Phenotypic identification, serotyping, and susceptibility testing were performed by standard microbiological procedures. The predominant serotypes of C. jejuni were Lior 36, 2 and 4 and of C. coli were Lior 8, 29 and 55. Resistance to nalidixic acid increased significantly during 1991-2000 and the frequency of isolates resistant to both nalidixic acid and ciprofloxacin in Bangkok was significantly greater than in rural settings. In 1996-2000, a significant trend was observed in C. jejuni isolates resistant to ciprofloxacin from Bangkok but not for macrolide resistance from both settings. In summary, fluoroquinolone resistance among C. jejuni and C. coli isolates became widespread in both Bangkok and rural settings in Thailand in the 1990s while widespread resistance to macrolides was undetected.

Characterization of antimicrobial resistance, plasmids, and gene cassettes in Shigella spp. from patients in vietnam.

The objective of the study was to investigate antimicrobial resistance, plasmids and class 1 integrons in 150 Shigella strains isolated from patients with diarrhea in Vietnam. Most isolates were resistant to the majority of antimicrobial agents used for treatment in the isolation areas and 90% were resistant to three or more antibiotics. A total of 20 strains yielded class 1 integrons, which harbored oxa1, dfrA, orfF, and aadA gene cassettes. The most common gene cassette, aadA2, was always located closest to the 3' conserved segment of the integrons and oxa1 and dfrA closest to the 5' end. Plasmid profiles of the 20 class 1 integron-positive strains all contained more than one plasmid, and 14 different profiles were found. No correlation was found between species, antibiograms, plasmid profiles, or presence of class 1 integrons. Conjugation resulted in 25 transconjugants, which all were resistant to four or more antimicrobial agents and all harbored at least one plasmid (>60 kb). Class 1 integrons were detected in 64% of the transconjugants. Phenotypic resistance pattern and plasmid profiles of the transconjugants seemed independent of the presence of an integron. Class 1 integrons seemed of less importance in phenotypic antibiograms and in transfer of resistance genes than conjugative plasmids.

Trends in antibiotic resistance among diarrheal pathogens isolated in Thailand over 15 years.

Antibiotic resistance trends were examined for Shigella species, nontyphoidal Salmonella species, enterotoxigenic Escherichia coli (ETEC), and Campylobacter species isolates from indigenous persons and travelers in Thailand for up to 15 years. Resistance to trimethoprim-sulfamethoxazole was found in >90% of Shigella and 40% of ETEC and nontyphoidal Salmonella isolates. Resistance to nalidixic acid was found in 97%-100% of Shigella dysenteriae 1 strains isolated between 1992 and 1995. Ciprofloxacin resistance was detected in 1% of ETEC isolates in 1994 and 1995 and in one of 349 nontyphoidal Salmonella isolates in 1995. Ciprofloxacin resistance among Campylobacter species increased from zero before 1991 to 84% in 1995 (P < .0001). Azithromycin resistance was found in 7%-15% of Campylobacter isolates in 1994 and 1995, as well as 15% of ETEC and 3% of Salmonella isolates in 1995. Enteric pathogens in Thailand have developed resistance to virtually all antibiotics routinely used in the treatment of diarrhea, as well as the newer fluoroquinolone and macrolide classes of drugs.