Transferable trimethoprim resistance in Shigella strains.
The susceptibility patterns of 35 Shigella isolates (16 S. flexneri, 14 S. dysenteriae and 5 S. sonnei) to trimethoprim (Tp) and various antibiotics including amoxycillin, amoxycillin-clavulanic acid, nalidixic acid, ciprofloxacin, ceftazidime and ceftriaxone, were investigated. Twenty-two (62.8%) strains were resistant to Tp with a minimal inhibitory concentration (MIC50) value of 512 mg/L. Only six isolates were amoxycillin resistant, to which clavulanic acid restored sensitivity in all of them. None of the isolates were resistant either to extended spectrum cephalosporins or to quinolones. Resistance to Tp was transferred from 7 of the 22 isolates (31.8%) to the recipient Escherichia coli K12. Tp MIC values of the transconjugants were 512 mg/L. In no strain could amoxycillin resistance be transferred. Our results indicate that as the prevalence of transferable Tp resistance in Shigella isolates in Izmir is substantially high, alternative antimicrobial agents should be considered for empirical antibiotic therapy.
Dokuz Eylül University, School of Medicine, Department of Infectious Diseases and Clinical Microbiology, Inciralti, Yzmir, Turkey.
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Yüce
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Gülay
M A
MA
Mehr
S G
SG
Amyes
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Cakir
N
N
Yulug
D000658:Amoxicillin / Q000494:pharmacology; D019980:Amoxicillin-Potassium Clavulanate Combination / Q000494:pharmacology; D000890:Anti-Infective Agents / Q000494:pharmacology; D002442:Ceftazidime / Q000494:pharmacology; D002443:Ceftriaxone / Q000494:pharmacology; D002511:Cephalosporins / Q000494:pharmacology; D002939:Ciprofloxacin / Q000494:pharmacology; D003227:Conjugation, Genetic; D004359:Drug Therapy, Combination / Q000494:pharmacology; D008826:Microbial Sensitivity Tests; D009268:Nalidixic Acid / Q000494:pharmacology; D010406:Penicillins / Q000494:pharmacology; D010957:Plasmids / Q000235:genetics; D012760:Shigella / Q000187:drug effects* / Q000235:genetics; D014295:Trimethoprim / Q000494:pharmacology; D014296:Trimethoprim Resistance / Q000235:genetics*
D000890:Anti-Infective Agents; D002511:Cephalosporins; D010406:Penicillins; D009268:Nalidixic Acid; D002939:Ciprofloxacin; D019980:Amoxicillin-Potassium Clavulanate Combination; D002443:Ceftriaxone; D000658:Amoxicillin; D002442:Ceftazidime; D014295:Trimethoprim