MECHANISMS OF RESISTANCE TO CIPROFLOXACIN AND GENETIC DIVERSITY OF ESCHERICHIA COLI STRAINS ORIGINATING FROM URINE CULTURES PERFORMED FOR ROMANIAN ADULTS.

Urinary tract infections (UTI) with Escherichia coli are among the most common infections presenting in general practice. Fluoroquinolones (FQs) are relied on for their empirical therapy but recent reports indicate a concerning increase in the percentage of FQ-resistant E. coli isolates in many countries, including Romania. Sixty E. coli strains with ciprofloxacin resistance and cephalosporin susceptibility isolated from urine specimens of non-hospitalized patients during a five-month period (October 2014 - February 2015) were further analyzed to determine the molecular basis of FQ resistance (i.e. mutations in chromosomal gyrA, gyrB, parC genes and presence of plasmid-borne qnrA, qnrB, qnrS, and aac(6'-Ib-cr genes), the phylogenetic background (i.e. phylogenetic groups A, B1, B2, C, D, E, F or clade I), O25b/ST131 status, and genetic relatedness inferred from the XbaI pulsed-field gel electrophoresis (PFGE) profiles as a measure of isolate-specific genetic composition. The PCR-based phylotyping showed that most strains were assigned to non-B2 phylogenetic groups (i.e. group A/21 strains, group B1/14 strains, group B2/10 strains, group C/8 strains, group D/3 strains, group F/4 strains). Already described chromosomal mutations associated to FQ resistance were found, the strains being double gyrA mutants (i.e. Ser83Leu, Asp87Asn) with one or two parC mutations (e.g. Ala56Thr, Ser80Ile, Glu84Gly). Seven percent of the strains harboured plasmid-borne genes qnrS1 (2 strains) and aac(6'-Ib-cr (2 strains). Based on the PCR results, 15% of the strains were members of the O25b/ST131 clone and possessed the gyrA/parC allele combination which is considered as hallmark of H30 subclone. PFGE genotyping revealed a genetically diverse population of FQ-resistant E. coli. ST131 strains displayed more homogeneous PFGE profiles than non-ST131. The ST131 cluster extended to 77.74% similarity versus 60% overall. These findings underscore the need for ongoing surveillance to capture the complexity of the emerging population of FQ-resistant strains disseminated across our community.

Screening for group B streptococcus: a private laboratory experience.

We examined group B streptococcus (GBS) isolates colonizing women at the 35-37 weeks of pregnancy. A total of 257 group B streptococcus (GBS) isolates for serotyped using direct agglutination with a set of commercially available antisera (Ia, Ib, II, III, IV, and V) and tested for susceptibility to antimicrobials (penicillin, macrolides, lincosamides, fluoroquinolones and tetracyclines). Fourteen isolates could not be serotyped with the antisera set used in the study. Serotype III was the predominant serotype (33%), followed by serotypes V (23%), and Ia (20%). Whereas all isolates were susceptible to penicillin, the rates of susceptibility to the other antimicrobials tested were the following: 91% for ofloxacin, 80% for clindamycin, 77% for erythromycin, and 4% for tetracycline. More than half (67%) of the macrolide resistant isolates belonged to serotypes V and III. A systematic surveillance of the autochthonous GBS serotypes, performed at the level of laboratories processing a high number of human specimens, is mandatory for strengthening the national epidemiological GBS surveillance. While penicillin remains the drug of choice for intrapartum prophylaxis, the resistance of autochthonous GBS isolates to other antibiotics should be actively monitored.