Molecular Characterization of Quinolone-Resistant Neisseria gonorrhoeae Isolates from Brazil

Abstract

Despite the rapid spread of antibiotic resistance among gonococci worldwide, limited reports are available from Brazilian locations. In the present study, 25 quinolone-resistant Neisseria gonorrhoeae (QRNG) strains isolated in Rio de Janeiro, Brazil, were characterized by phenotypic and molecular methods, including analysis of mutations in the gyrA and parC genes. They represented 16.5% of the N. gonorrhoeae isolates obtained during a survey performed from 2006 to 2010. A trend for increasing resistance to ciprofloxacin was observed in the period investigated. The most prevalent pattern of mutation observed among QRNG isolates, Ser-91 to Phe and Asp-95 to Gly in gyrA and Ser-87 to Arg in parC, was detected in 40% of the isolates exhibiting MICs ranging from 4 to >32 g/ml. Gonorrhea is among the most prevalent sexually transmitted diseases (STDs) throughout the world. The causative agent, Neisseria gonorrhoeae, predominantly infects human urogenital tract, causing cervicitis, urethritis, and rectal infections. In 2003, the incidence of gonococcal infections in Brazil was estimated in 1,54 million of cases, being 657,139 cases in the Southeast region and more than 130,000 cases in Rio de Janeiro state (5). Recently, two studies conducted among men attending STD clinics (1) and among pregnant women (15) in six Brazilian cities revealed prevalences of infection by Neisseria gonorrhoeae of 18.4 and 1.5%, respectively.Since the emergence and increasing occurrence of plasmidmediated high-level or chromosomally mediated low-level resistance to penicillin and/or tetracycline, fluoroquinolones (ciprofloxacin or ofloxacin) or cephalosporins (ceftriaxone and cefixime) constitute the therapeutic regimen recommended by the World Health Organization for treatment of gonococcal infections worldwide (25).However, the emergence of quinolone-resistant N. gonorrhoeae (QRNG) isolates has generated significant concern in several countries (13,26,31). Mechanisms of quinolone resistance in N. gonorrhoeae isolates include point mutations at the "quinolone resistance-determining regions" (QRDRs) of the gyrA and parC genes which code for the enzymes DNA gyrase and topoisomerase IV, respectively, that were the target of this drug, conferring high-level quinolone resistance (13).In Brazil, reports on the antimicrobial susceptibility of N. gonorrhoeae have been sporadically available, and only a few isolates with decreased susceptibility to ciprofloxacin were described (2, 11, 12). In 2007, we detected the occurrence of resistance to ciprofloxacin in 7.7% (4/52) of the N. gonorrhoeae isolates recovered from male urethral specimens or vaginal specimens in Rio de Janeiro, Brazil (A. A. Uehara and S. E. L. Fracalanzza, unpublished data). Simultaneously, a resistance rate of 3.1% was found in strains isolated from patients attending the STD Service of the University of São Paulo teaching hospital, in São Paulo, Brazil (3).The aim of the present study was to characterize ciprofloxacin-resistant N. gonorrhoeae isolates recovered in Rio de Janeiro,...

Molecular Characterization of Fluoroquinolone-Resistant Moraxella catarrhalis Variants Generated In Vitro by Stepwise Selection

“…In Gram-negative cocci, such as Neisseria gonorrhoeae and N. meningitidis, the mechanism of fluoroquinolone resistance involves amino acid substitutions in the quinolone resistance-determining region (QRDR) of GyrA and ParC and reduced fluoroquinolone accumulation in the cells (7)(8)(9). In a recent study, we showed that T80I substitution in GyrA is involved in low-level fluoroquinolone resistance in M. catarrhalis clinical isolates (10).…”

Recent advances in the development and use of molecular tests to predict antimicrobial resistance inNeisseria gonorrhoeae

“…For instance, the gyrA S91F alteration alone has proven to be highly predictive for intermediate susceptibility and resistance to CIP. The suitability of this AMR determinant to predict CIP resistance (or susceptibility when mutation is lacking) has been shown in several studies performed in many different countries worldwide (e.g., Canada [74], Brazil [75], Australia [76], USA [77], and Switzerland [78]), and further confirmed by the validation studies of the molecular CIP AMR methods mentioned above [44,45,47,60]. Similarly, mutations in at least three 23S rRNA alleles have shown to be a good predictor of moderate-to high-level AZM resistance (i.e., MIC>2 µg/ml), although low-level resistance may still be observed due to mutations in other AMR determinants (e.g., mtrR) [2,35].…”

“…excluding settings in Asia with 90-100% resistance, identification of CIP susceptibility would be particularly valuable to guide personalized treatment and spare the use of dual antimicrobial therapy (CRO plus AZM). The detection of the GyrA S91F alteration has been proven to be highly indicative of a CIP-resistant phenotype in several validation and other epidemiological studies A c c e p t e d M a n u s c r i p t 23 [44,45,47,60,[74][75][76][77][78]. However, considering the relatively limited number of wellcharacterized clinical, and especially extra-genital, samples tested so far, additional testing using molecular assays with appropriate controls would be advisable before applying those tests on all NG positive NAAT samples.…”

Mutaciones en la región determinante de resistencia a quinolonas (QRDR) del gen gyrA de Neisseria gonorrhoeae presente en muestras clínicas de hombres que tienen sexo con hombres

“…En Brasil, la caracterización molecular de aislados de Neisseria gonorrhoeae con alta resistencia a ciprofloxacino mostraron en la QRDR del gen gyrA una mutación doble prevalente de serina a fenilalanina en la posición 91 y de aspartato a glicina en posición 95 (Uehara et al 2011); igualmente en India se reportó un patrón similar de mutaciones (Ser91-Phe y Asp95-Gly) en aislados de Neisseria gonorrhoeae resistente a gatifloxacino, lomefloxacino, enoxacino, ciprofloxacino, norfloxacino y ofloxacino (Kulkarni et al 2012). Nosotros identificamos un patrón similar de mutaciones en ambas posiciones de la QRDR, esto nos indica la relevancia de estas mutaciones en la resistencia de Neisseria gonorrhoeae a un mayor número de fluoroquinolonas y la utilidad de esta información para establecer recomendaciones de tratamiento efectivas dependiendo del grupo poblacional, tipo de resistencia informada y rutas de diseminación de las cepas resistentes.…”