Suboptimal clinical response to ciprofloxacin in patients with enteric fever due to Salmonella spp. with reduced fluoroquinolone susceptibility: a case series

Abstract

Background: Salmonella spp. with reduced susceptibility to fluoroquinolones have higher than usual MICs to these agents but are still considered "susceptible" by NCCLS criteria. Delayed treatment response to fluoroquinolones has been noted, especially in cases of enteric fever due to such strains. We reviewed the ciprofloxacin susceptibility and clinical outcome of our recent enteric fever cases.

Clinical profile of enteric fever: a prospective study of fifty enteric fever patients

“…10 mg/kg twice daily for 10 days) or ofloxacin (10 to 15 mg/kg divided twice daily for 7 to 10 days). 17 Ciprofloxacin resistance was seen in 22% (11) in our study.…”

“…Resistance to ciprofloxacin of S typhi appears to be increasing, especially in the Indian subcontinent. 15 Patients infected with relatively quinolone-resistant S typhi strains (resistant to nalidixic acid and a minimal inhibitory ciprofloxacin concentration of 0.125 to 1 mg/dl) who receive short course quinolone therapy (i.e. <5 days), may not demonstrate clinical recovery and could require repeated or alternative treatment.…”

Molecular Basis of Resistance Displayed by Highly Ciprofloxacin-Resistant Salmonella enterica Serovar Typhi in Bangladesh

“…This has resulted in the rapid emergence of Salmonella enterica serovar Typhi strains with reduced susceptibility to ciprofloxacin due to a point mutation in the gyrA gene, at either Ser-83 or Asp-87 (1,7,12,14,17). These strains are associated with failure of or a delayed response to ciprofloxacin therapy (16).…”

Development of a Real‐Time PCR Assay for Detection of gyrA Mutations Associated with Reduced Susceptibility to Ciprofloxacin in Salmonella enterica Serovar Typhi and Paratyphi A

“…In this context, it is of great importance to know whether the S. enterica serovar Typhi and Paratyphi A strains have reduced susceptibility to CPFX (MIC Ն0.125 µg/ml) before medication (1,15,17). Hence, a rapid detection system can be useful for screening such strains using novel technologies that have advantages compared to the classical susceptibility tests.…”

“…(12). The breakpoint for the MIC of reduced CPFX susceptibility was defined as Ն0.125 µg/ml and Յ1 µg/ml (1,15,17) because reduced susceptibility to CPFX was not detectable using the current CLSI breakpoints. The estimated susceptibilities of all S. enterica serovar Typhi and Paratyphi A strains matched the susceptibility determined by the E-test (Table 3).…”