Mutant prevention concentration of nalidixic acid, ciprofloxacin, clinafloxacin, levofloxacin, norfloxacin, ofloxacin, sparfloxacin or trovafloxacin for Escherichia coli under different growth conditions

“…Subsequently, isolated examples were described in which correlation was low for a variety of fluoroquinolones with strains of Escherichia coli, Salmonella enterica, and Staphylococcus aureus (5,8,10), and a set of 20 clinical isolates of E. coli showed a low correlation (r 2 ϭ 0.58) for ciprofloxacin (6). To determine whether a low correlation between MICs and MPCs is likely to be a general phenomenon, we calculated the correlation coefficients for several quinolones with five bacterial species and for three macrolides with Streptococcus pneumoniae using data from published and unpublished studies of clinical isolates.…”

Section: Low Correlation Between Mic and Mutant Prevention Concentrationmentioning

confidence: 99%

Low Correlation between MIC and Mutant Prevention Concentration

Drlica¹,

Zhao²,

Blondeau

et al. 2006

Antimicrob Agents Chemother

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“…Therefore, the wide range of pH found in human urine can affect the ionization status of CIP and can thus modify its antimicrobial activity (16)(17)(18)(19). Regarding oxygen levels, it has been reported that growth under conditions of anaerobiosis affects bacterial susceptibility to CIP (20). Therefore, both parameters could, in principle, influence the resistance profiles of LLQR UTI strains, thus affecting the prognosis of treatment.…”

mentioning

confidence: 99%

Urinary Tract Physiological Conditions Promote Ciprofloxacin Resistance in Low-Level-Quinolone-Resistant Escherichia coli

Martín-Gutiérrez

Rodríguez-Beltrán

Rodríguez-Martínez

et al. 2016

Antimicrob Agents Chemother

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Escherichia coli isolates carrying chromosomally encoded low-level-quinolone-resistant (LLQR) determinants are frequently found in urinary tract infections (UTIs). LLQR mutations are considered the first step in the evolutionary pathway producing high-level fluoroquinolone resistance. Therefore, their evolution and dissemination might influence the outcome of fluoroquinolone treatments of UTI. Previous studies support the notion that low urine pH decreases susceptibility to ciprofloxacin (CIP) in E. coli. However, the effect of the urinary tract physiological parameters on the activity of ciprofloxacin against LLQR E. coli strains has received little attention. We have studied the activity of ciprofloxacin under physiological urinary tract conditions against a set of well-characterized isogenic E. coli derivatives carrying the most prevalent chromosomal mutations (⌬marR, gyrA-S83L, gyrA-D87N, and parC-S80R and some combinations). The results presented here demonstrate that all the LLQR strains studied became resistant to ciprofloxacin (according to CLSI guidelines) under physiological conditions whereas the control strain lacking LLQR mutations did not. Moreover, the survival of some LLQR E. coli variants increased up to 100-fold after challenge with a high concentration of ciprofloxacin under UTI conditions compared to the results seen with Mueller-Hinton broth. These selective conditions could explain the high prevalence of LLQR mutations in E. coli. Furthermore, our data strongly suggest that recommended methods for MIC determination produce poor estimations of CIP activity against LLQR E. coli in UTIs.C iprofloxacin (CIP) is one of the agents commonly utilized for treatment of urinary tract infections (UTIs) (1-3). It is used as an appropriate therapy in patients with UTI not requiring hospitalization in areas where the prevalence of resistance is under 10%. In addition, it is considered an effective treatment in the prevention of UTI in kidney transplant recipients (4, 5). However, during recent years a clear increase in resistance to fluoroquinolones (FQ) has been described worldwide (6, 7).The predominant causative agent of community-acquired UTI, Escherichia coli, acquires resistance mainly through chromosomal mutations in the genes encoding subunits of the DNA gyrase (gyrA and gyrB genes) and topoisomerase IV (parC and parE genes) or in regulatory genes affecting permeability or efflux (8). Some of these mutations lead to generation of low-level-quinolone-resistant (LLQR) E. coli mutants, with a CIP MIC that is higher than the epidemiological cutoff value but still below the resistance breakpoint for most FQs. A high (from 17% to 39%, depending on the study) prevalence of LLQR E. coli in UTIs has been previously described (8,9). However, the causes of this prevalence are unclear, as the high CIP levels found in the bladder after treatment should be sufficient to eradicate any susceptible bacteria.It has been stated that small increases in MIC values produced by LLQR mutations have a profound impact on t...

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Mutant prevention concentration of nalidixic acid, ciprofloxacin, clinafloxacin, levofloxacin, norfloxacin, ofloxacin, sparfloxacin or trovafloxacin for Escherichia coli under different growth conditions

Cited by 33 publications

References 21 publications

Evaluation of Meropenem Regimens Suppressing Emergence of Resistance in Acinetobacter baumannii with Human Simulated Exposure in an In Vitro Intravenous-Infusion Hollow-Fiber Infection Model

Evaluation of Meropenem Regimens Suppressing Emergence of Resistance in Acinetobacter baumannii with Human Simulated Exposure in an In Vitro Intravenous-Infusion Hollow-Fiber Infection Model

Low Correlation between MIC and Mutant Prevention Concentration

Urinary Tract Physiological Conditions Promote Ciprofloxacin Resistance in Low-Level-Quinolone-Resistant Escherichia coli

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