Typhoid fever due to a Salmonella typhi strain of reduced susceptibility to fluoroquinolones

Abstract

OBJECTIVE: To report a case of typhoid fever contracted in Portugal in 1994 due to a Salmonella typhi isolate which had reduced susceptibility to fluoroquinolone (MIC 1 mg/L of ciprofloxacin) and high level resistance to nalidixic acid (MIC greater-than-or-equal 56 mg/L). METHODS: Molecular studies of reduced susceptibility to fluoroquinolones comprised complementation tests with a wild-type allele and sequencing directly from PCR products of the gyrA gene. RESULTS: Complementation tests and DNA sequencing showed that a mutation occurred in the gyrA gene of this clinical isolate, resulting in a substitution of phenylalanine for serine at position 83 of GyrA. CONCLUSIONS: Because quinolones may be regarded as a treatment of choice in typhoid fever, it seems important now to recommend cautious use of these drugs as first-line therapy and possibly use of nalidixic acid resistance as a marker for detection of 'first-step' resistance to fluoroquinolones in S. typhi.

Serotype Distribution, Antibiotic Resistance and Clinical Features of Salmonella Infections

“…27 Salmonella suşlarında florokinolon grubu antibiyotiklerere de direnç geliştiği bildirilmektedir. 28 2000-2002 yılları arasında çok merkezli bir çalış-mada S. enteritidis serotiplerinde ampisiline %16,6, kloramfenikole %9,3, trimetoprim-sulfametoksazole %1, sefotaksime %0,7; siprofloksasine %0,3; S. typhimurium serotiplerinde sırası ile bu antibiyotiklere karşı %82,3, %0,9, %79,8, %3,7, %0,9 oranında direnç saptandığı bildirilmiştir. 29 Başka bir çalışmada 2001-2004 yılları arasında izole edilen Salmonella suşlarında ampisiline %49, trimetoprim-sulfametoksazole %5,6, kloramfenikole %6,7, nalidiksik asite %20, siprofloksasine %0 direnç bulunmuştur.…”

Outbreak of typhoid fever in vaccinated members of the French Armed Forcesin the Ivory Coast

“…In recent decades, typhoid fever has been largely eradicated from industrialized countries but remains a public health concern in developing countries, including Africa [4]. The emergence of fluoroquinolone-resistant Salmonella Typhi strains [5] and the spread of multiresistant strains [6][7][8] have been reported in recent years and point to the value of typhoid vaccination to prevent the disease [9].…”

Application of an In Vitro Infection Model and Simulation for Reevaluation of Fluoroquinolone Breakpoints for Salmonella enterica Serotype Typhi

“…The vast majority of nalidixic acidresistant strains remain within the current susceptible range for ciprofloxacin (Յ1 g/ml) as recommended by the National Committee for Clinical Laboratory Standards (NCCLS). However, the probability of clinical response to fluoroquinolone therapy in patients with invasive Salmonella infection is lower in those with nalidixic acid-resistant than with -susceptible strains (7,20,21,26,32,33). These data suggest that the current susceptibility breakpoints for fluoroquinolones published by the NCCLS may need to be altered to better predict clinical efficacy.…”

“…Mounting clinical evidence suggests that infections due to serovar Typhi and nontyphoidal strains resistant to nalidixic acid but susceptible to ciprofloxacin by NCCLS criteria may not respond to fluoroquinolone therapy (8,20,21,24,(31)(32)(33). While the reasons for treatment failure are multifactorial, PK-PD remains an important predictor of response to antimicrobial therapy, and failure to achieve adequate PK-PD targets may be a likely FIG.…”