RESUMO
BACKGROUND: We describe the antimicrobial susceptibility pattern of 100 typhoidal Salmonella isolates recovered from blood cultures and also investigate the association of decreased ciprofloxacin susceptibility with mutations in the genes coding for DNA gyrase and topoisomerase IV in 55 isolates. METHODS: The study was conducted between January 2013 and December 2015 at a tertiary care centre in north India. Antimicrobial susceptibility testing was performed by Kirby-Bauer disc diffusion and E-test. Genotypic characterization included the screening of mutations in the quinolone resistance-determining region of gyrA, gyrB, parC, and parE by PCR. DNA sequence analysis was done for 55 isolates. RESULTS: Out of 100 isolates recovered 80 were S. Typhi, 18 were Paratyphi A and two were Paratyphi B. Eighty two percent (66/80) of S. Typhi and 15/18 S. Paratyphi A showed decreased ciprofloxacin susceptibility. The most common mutation in gyrA led to a change at codon 83 of serine to phenylalanine (n=37) or tyrosine (n=12). Five S. Typhi isolates that were resistant to ciprofloxacin (MICs of 12, 16, 24 and 32 µg/ml) had a second mutation at codon 87 in the gyrA gene changing aspartate to asparagine. CONCLUSIONS: There is a need to urgently review the use of fluoroquinolones for the management of enteric fever in endemic areas.
Assuntos
Ciprofloxacina/farmacologia , DNA Girase/genética , DNA Topoisomerase IV/genética , Farmacorresistência Bacteriana/genética , Salmonella paratyphi A/genética , Salmonella typhi/genética , Febre Tifoide/microbiologia , Antibacterianos/farmacologia , Proteínas de Bactérias/genética , Testes de Sensibilidade a Antimicrobianos por Disco-Difusão , Fluoroquinolonas , Genótipo , Humanos , Índia , Testes de Sensibilidade Microbiana , Mutação , Reação em Cadeia da Polimerase , Salmonella enterica/efeitos dos fármacos , Salmonella enterica/genética , Salmonella enterica/isolamento & purificação , Salmonella paratyphi A/efeitos dos fármacos , Salmonella paratyphi A/isolamento & purificação , Salmonella paratyphi B/efeitos dos fármacos , Salmonella paratyphi B/genética , Salmonella paratyphi B/isolamento & purificação , Salmonella typhi/efeitos dos fármacos , Salmonella typhi/isolamento & purificação , Análise de Sequência de DNA , Sorogrupo , Centros de Atenção Terciária , Febre Tifoide/tratamento farmacológicoRESUMO
BACKGROUND: We describe the antimicrobial susceptibility pattern of 64 blood stream isolates of Salmonella enterica serotypes Typhi and Paratyphi A studied from January 2013 to December 2014 at a tertiary care centre in North India. METHODS: Isolates were identified by standard biochemical reactions and confirmed by slide agglutination using specific antisera. Antimicrobial susceptibility testing was performed by Kirby-Bauer disc diffusion method and by E-test. RESULTS: In this study, 92% (46/50) of Salmonella Typhi and all Paratyphi A (n=14) isolates were susceptible to ampicillin, chloramphenicol and cotrimoxazole. Eighty percent of Typhi (40/50) and 64% (9/14) of Paratyphi A were intermediately susceptible to ciprofloxacin. Nineteen percent (12/64) of isolates were resistant to ciprofloxacin. No resistance to ceftriaxone and azithromycin was detected. CONCLUSIONS: Our study adds to the current knowledge of world-wide reports of multidrug resistance in S. Typhi.
