Frameshift mutation (690delG) in cpxA contributes to the extensive drug resistance of a Serratia marcescens clinical isolate.

OBJECTIVES: To identify the genetic change responsible for resistance to penicillins, extended-spectrum cephalosporins (ESCs), aminoglycosides and ciprofloxacin in a Serratia marcescens clinical isolate recovered from a pancreatic abscess 6 weeks after a WT strain was isolated from the same patient. The impact on the fitness was also assessed. METHODS: The genomes of both S. marcescens isolates were sequenced using Illumina technology, assembled, annotated and compared with each other. PCR amplification followed by Sanger sequencing was carried out to confirm the mutation. Complementation of the resistant isolate with a recombinant plasmid harbouring the WT gene was performed. The growth rates were measured for both isolates in LB medium. RESULTS: Comparative genomic analysis disclosed only one frameshift mutation (690delG) in the cpxA gene, which codes for the histidine kinase of a two-component system (TCS). This change introduced a premature termination codon, leading to the truncated CpxA_HatR variant that contained 234 amino acids instead of 464. Complementation, which consisted of transfer of the WT cpxA into the resistant S. marcescens derivative, restored completely its susceptibility to ESCs, aminoglycosides and ciprofloxacin, thus confirming the contribution of the CpxA_HatR variant to resistance. Growth analysis showed that the fitness of the resistant isolate was unchanged. CONCLUSIONS: This study shows for the first time that constitutive activation of the Cpx pathway can per se confer resistance to ESCs and ciprofloxacin, in addition to the aminoglycoside resistance usually described. It sheds new light on the role of altered TCSs in fostering bacterial survival.

Antibiotics for amniotic-fluid colonization by Ureaplasma and/or Mycoplasma spp. to prevent preterm birth: A randomized trial.

OBJECTIVE: To assess whether antibiotics used for treatment in asymptomatic second-trimester women positive for Mycoplasma or Ureaplasma spp. detected by amniotic-fluid PCR prevents preterm delivery. DESIGN: A randomized, double-blind, placebo-controlled trial. SETTING: 10 maternal fetal medicine centers in France. POPULATION: Women with a singleton pregnancy who underwent amniocentesis between 16 and 20 weeks' gestation (weeks) for Down syndrome screening. A sample of 238 women with PCR-positive findings per treatment group was needed to show a 50% reduction in the preterm delivery rate. METHODS: Amniotic fluid was tested. Women with positive findings on real-time PCR of amniotic fluid for Mycoplasma hominis, Mycoplasma genitalium, Ureaplasma urealyticum and Ureaplasma parvum were randomized to receive josamycin or placebo. Amniotic fluid was also tested for 16S PCR. MAIN OUTCOME MEASURES: The primary outcome was delivery before 37 weeks. RESULTS: In total, 1043 women underwent amniotic-fluid screening with specific PCR detection between July 2008 and July 2011: PCR detection failed in 27 (2.6%), and 20 (1.9%) underwent termination of pregnancy. Among the 1016 women with PCR results, 980 had available data for the primary outcome (delivery before 37 weeks) and 29 (3.0%) were positive for Ureaplasma and/or Mycoplasma spp. Because of the low rate of women with PCR-positive findings, the trial was stopped prematurely. In total, 19 women were randomized to receive placebo (n = 8) or josamycin (n = 11) and their characteristics were comparable, as was the rate of preterm delivery and secondary outcomes. In comparing all PCR-positive and -negative women regardless of treatment, PCR positivity for Ureaplasma and/or Mycoplasma spp. was not associated with any adverse pregnancy or neonatal outcome. Amniotic-fluid screening by 16S PCR showed no other bacterial colonization associated with preterm birth. CONCLUSIONS: Because of a low amniotic fluid colonization rate, the trial was interrupted. Maternal amniotic-fluid colonization by Mycoplasma and/or Ureaplasma spp. at 16-20 weeks in asymptomatic women is rare and not associated with adverse pregnancy outcomes. TRIAL REGISTRATION: ClinicalTrials.gov NCT00718705.

Characterization of Streptococcus pyogenes isolates responsible for adult meningitis in France from 2003 to 2013.

Sixty-three cases of Streptococcus pyogenes meningitis in adults were studied. Three predominant emm types were associated with meningitis: emm1 (44%), emm3 (11%), and emm6 (11%). Streptococcal toxic shock syndrome and mortality rates were 40% and 38%, respectively.

Bacillus cereus, an unusual cause of fulminant liver failure: diagnosis may prevent liver transplantation.

Bacillus cereus is a well-known cause of foodborne disease usually of benign course. Here, we present the case of a 15-year-old boy who developed reversible fulminant liver failure associated with rhabdomyolysis after pasta consumption. Suspecting B. cereus as the aetiological agent may prevent unnecessary liver transplantation.

Streptococcus australis meningitis.

We report a case of meningitis due to Streptococcus australis, a species of oral streptococcus. Accurate identification was performed by various molecular techniques.

Molecular mechanisms of tetracycline and macrolide resistance and emm characterization of Streptococcus pyogenes isolates in Tunisia.

Streptococcus pyogenes or group A Streptococcus, a major human pathogen, remains susceptible to beta-lactams, but resistance to other antibiotics is becoming more common. The purpose of this study was to characterize both phenotypic and genotypic epidemiological markers of group A Streptococcus and to identify the mechanisms of resistance to macrolides and tetracyclines. A total of 103 strains, isolated at Charles Nicolle University Hospital of Tunis, were investigated. The rate of resistance to erythromycin was low (5%), whereas a high rate of tetracycline resistance was found (70%). All the macrolide-resistant isolates expressed the constitutive macrolide, lincosamide, and streptograminB phenotype and harbored the erm(B) gene. Resistance to tetracycline was mainly due to the tet(M) gene, which is commonly associated with the conjugative transposon Tn916. No significant association was found between erm(B) and tet(M) genes. The tetracycline-resistant strains belonged to 28 distinct emm types. Among them, emm118 was the most prevalent type, followed by emm42, std432, emm76, and emm18. However, emm1, emm4, emm6, emm28, and emm3 were the most frequent types among tetracycline susceptible isolates. Only emm118 and emm42 types (p ≤ 0.05) were significantly associated with resistance to tetracycline.

Globicatella sanguinis meningitis associated with human carriage.

Globicatella sanguinis is a rare cause of acute meningitis. We demonstrated human carriage of Globicatella by identifying cefotaxime-resistant strains in groin and rectal specimens 9 months after invasive infection. The pathogenic strain isolated from the cerebrospinal fluid and the carriage strains were accurately identified by sodA gene sequence analysis.

Primary peritonitis due to Streptococcus pyogenes with reduced susceptibility to fluoroquinolones.

We report the 1st case of primary peritonitis caused by Streptococcus pyogenes with a reduced susceptibility to fluoroquinolones in a healthy woman, leading to a clinical and microbiological treatment failure. DNA sequencing of parC and gyrA revealed the association of the following 3 substitutions in ParC: Ser80Pro, Asp91Asn, and Ser140Pro.