Extremely low prevalence of erythromycin-resistant Streptococcus pyogenes isolates and their molecular characteristics by M protein gene and multilocus sequence typing methods

Background: Group A streptococci (GAS) are notorious bacteria causing a wide variety of clinical manifestations ranging from mild, acute streptococcal pharyngitis to chronic non-suppurative diseases and immunological sequelae. They are further complicated by the global rise on the emergence of macrolide resistance among these bacteria in which several M protein gene (emm) and sequence types are associated with invasive diseases. Objectives: The current study aimed at determining the erythromycin resistance patterns and molecular characteristics of GAS clinical strains by emm and multilocus sequence typing (MLST) methods. Methods: Thirty-five GAS clinical isolates were subjected to antibiotic susceptibility testing by disk diffusion method. The minimum inhibitory concentration (MIC) of erythromycin against GAS by E-test was determined. Clinical and laboratory standards institute (CLSI) guideline was used for the interpretation of results. Detection of ermA, ermB, and mefA genes by polymerase chain reaction (PCR) was performed and emm typing was done by amplification and sequencing of emm genes per standard protocol. Allele and sequence type (ST) of GAS were obtained using the S. pyogenes MLST database. Results: All the isolates were sensitive to erythromycin, penicillin, clindamycin, chloramphenicol, and vancomycin (100%). Resistance to tetracycline was 54.3%. The mefA gene was found in one erythromycin susceptible isolate. No other erythromycin resistance genes were detected in the isolates. Twenty different emm types were found and the most frequent emm types/subtypes detected were emm1, emm18.21, emm28.5, emm97.4, and emm102.2 (each 8.6%). However, no new emm type was detected. A total of 15 sequence types (STs), eight clonal clusters (CCs), and eight singletons were identified among 21 representative isolates. Three isolates exhibited CC1 (ST28/emm1). Conclusions: High susceptibility of GAS isolates against erythromycin could be due to low antibiotic selective pressure in Malaysian clinical settings. High diversity of emm and ST types revealed the heterogenic nature of the strains circulating in Malaysian hospitals. Continuous epidemiological monitoring by molecular typing methods is warranted to improve the management strategies of GAS infections in future

Genotyping and drug resistance profile of Candida spp. in recurrent and one-off vaginitis, and high association of non-albicans species with non-pregnant status

Recurrent vulvovaginal candidiasis affects women worldwide and the resistance to azole drugs may be an important factor. The extent of strain-to-strain variation within a species and its relationship to the ability of the organism to colonize the vulvovaginal mucosa is not well established. The aims of this study were to compare: (i) the genotypes of Candida strains in sequential infections in patients with recurrent vaginitis, (ii) the genotypes of strains in patients with only one episode of infection in a period of 1 year and (iii) determine the in vitro antifungal susceptibilities of strains that cause recurrent vaginitis. Fifty-one cultured specimens from six distinct Candida species were genotyped via random amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR) method using the ERIC1 and ERIC2 primers (ERIC, enterobacterial repetitive intergenic consensus). Statistical analyses allowed three different scenarios to be discerned for recurrent cases: (i) strain maintenance without genetic variation, (ii) strain maintenance with minor genetic variation and (iii) outright strain replacement. The genetic relatedness between strains from patients with recurrent vaginitis and patients with single episode of vaginitis were demonstrated by the dendogramme and the mean pairwise similarity coefficient S(AB) for the intergroup comparison was 0.223. However, intragroup genetic relatedness was slightly higher than intergroup comparison, with mean S(AB) of 0.261 and 0.331 for Groups I and II, respectively. A high proportion of Group I isolates (87.5%) causing recurrent infections were resistant to ketoconazole, whereas 41.7% of these isolates were cross-resistant to both clotrimazole and ketoconazole as shown by the in vitro antifungal susceptibility test, especially for C. glabrata isolates. Pregnancy status of patients displayed a highly significant association with C. albicans species whereas non-albicans species had a markedly higher prevalence in non-pregnant patients (p<0.001). These results may have a profound impact on the management of vaginal candidiasis, especially in recurrent cases