An intrinsic pattern of reduced susceptibility to fluoroquinolones in pediatric isolates of Streptococcus pyogenes

Abstract

A total of 116 clinical isolates collected in 2003 from a tertiary pediatric hospital and a primary pediatric department in Chicago, Illinois were screened for reduced susceptibility to selected fluoroquinolones by disc diffusion. Correlation between reduced susceptibility and point mutations in the quinolone resistance-determining region of parC and gyrA genes were evaluated, and point mutations were compared with other reports of isolates derived from adult or mixed patient populations. 9% of isolates had reduced susceptibility to one or more of these fluoroquinolones by Etest: ciprofloxacin, levofloxacin, moxifloxacin. A single point mutation (Ser-79) in parC seemed responsible for the reduced susceptibility. Resistant S. pyogenes isolates were compared using M/ emm type, RepPCR, and pulsed-field gel electrophoresis (PFGE). RepPCR provided no more separation of strains than M/emm typing and PFGE results with SgrA1 were more discriminatory than with SmaI. The majority of these isolates were M/emm type 6. PFGE analysis using SgrA1 demonstrated 2 different resistant strains among the M/emm type 6 isolates. The findings suggest that a population of S. pyogenes with an intrinsic reduced susceptibility to fluoroquinolones exists in pediatric clinical isolates. Monitoring of amino acid changes in both parC and gyrA will assist in the prediction of emergence of high level fluoroquinolone resistance.

Emergence of Ciprofloxacin-Nonsusceptible Streptococcus pyogenes Isolates from Healthy Children and Pediatric Patients in Portugal

“…To the best of our knowledge, this is the first study describing the rate of ciprofloxacin nonsusceptibility among S. pyogenes isolates collected from oropharyngeal colonization during a 7-year period (2000 to 2006). The rate of ciprofloxacin nonsusceptibility among our sample of clinical isolates was comparable to those previously reported among pediatric patients in Brazil, Belgium, and the United States (6% to 9%) (15,27,29); however, it was slightly lower than that found in a study from Spain (13.6%) (16) and much lower than the one found in Brussels (22.5%) (27).…”

“…Streptococcus pyogenes clinical isolates with reduced susceptibility to fluoroquinolones (1,3,8,14,16,18,27,29) or with high-level resistance (15,16,(23)(24)(25)28) have been described previously, and the reduced susceptibility to fluoroquinolones is mediated by point mutations in the quinolone resistancedetermining region (QRDR) of the parC gene (3,16,18) whereas high-level resistance has been associated with mutations in the QRDRs of both parC and gyrA genes (23,28). To the best of our knowledge, there are no reports documenting the prevalence and characterization of fluoroquinolone-nonsusceptible S. pyogenes associated with asymptomatic colonization.…”

Disease Manifestations and Pathogenic Mechanisms of Group A Streptococcus

“…Resistance to Fluoroquinolones GAS isolates with low-level resistance to fluoroquinolones have been reported by several groups (506,(520)(521)(522)(523)(524). GAS strains with high-level fluoroquinolone resistance occur far less frequently (499,521,(524)(525)(526).…”

“…GAS strains with high-level fluoroquinolone resistance occur far less frequently (499,521,(524)(525)(526). Low-level fluoroquinolone resistance in GAS is brought about by point mutations within the quinolone resistance-determining region (QRDR) located within topoisomerase IV (parC and parE) (499,521,(524)(525)(526). High-level resistance results from additional point mutations in the DNA gyrase (gyrA and gyrB) genes (521).…”

Genome-wide analysis of Streptococcus pyogenes associated with pharyngitis and skin infections. (c2015)

“…Fluoroquinolone resistance is another feature of GAS that has been reported by several studies (Wajima et al, 2008;Yan et al, 2008;Montes et al, 2010). Two types of resistance are observed, a low-level resistance, and a high level resistance which occurs much less frequently (Perez-Trallero et al, 2011).…”