Phenotypic and genotypic quinolone resistance in Escherichia coli underlining GyrA83/87 mutations as a target to detect ciprofloxacin resistance.

BACKGROUND: Quinolone resistance (QR) is one component of the MDR emerging in Escherichia coli and is of particular concern given the widespread use of fluoroquinolones. OBJECTIVES: To characterize the QR phenotypes and genotypes in E. coli responsible for bloodstream infections and to propose molecular determinants that could be targeted to predict ciprofloxacin resistance. METHODS: E. coli isolates from blood cultures in three French hospitals were studied for quinolone MICs and characterization of genotypic QR determinants (QRg). RESULTS: Among 507 isolates tested for MICs, 148 (29.2%) were resistant to quinolones based on EUCAST breakpoints and 143 (28.2%) harboured at least one QRg. QRg were mainly mutations in the QRDR (138 isolates, 27.2%), with 55.8% of these isolates carrying at least three QRDR mutations. gyrA mutations predominated (92.8%) followed by parC (61.6%), parE (32.6%) and gyrB (1.4%) mutations. Only 4.7% of the isolates harboured a plasmid-mediated quinolone resistance (PMQR) gene: aac(6')-Ib-cr (60.0%) or qnr (qnrS, qnrB) (32.0%). For the first time in France, we reported the qepA4 allele of the plasmid-encoded efflux pump QepA. Only five isolates carried PMQR without a QRDR mutation. The positive predictive value (PPV) for ciprofloxacin resistance was 100% for any QRg and 99.2% for gyrA mutations specifically. CONCLUSIONS: QR observed in E. coli isolates involved in bloodstream infections is still mainly due to QRDR mutations, especially at codons GyrA83/87, which could be used as a molecular target to rapidly detect resistance.

Fatal transfusion-transmitted infection due to Citrobacter koseri.

BACKGROUND: Transfusion-transmitted bacterial infection (TTBI) is still one of the most feared complications of blood transfusion. CASE REPORT: We report a fatal case involving an 8-year-old child with congenital dyskeratosis complicated by severe aplastic anemia who was regularly transfused with platelet (PLT) concentrates for 5 years. The patient received an apheresis PLT concentrate (APC) on Day 0 due to thrombocytopenia complicated by mucocutaneous hemorrhage. Thirty minutes after the start of the transfusion, bradycardia and dyspnea appeared, quickly followed by chills, nausea, vomiting, headache, and hyperthermia. TTBI was suspected and the patient was immediately treated with intravascular antibiotherapy. On Day 3, the patient developed severe acute respiratory distress syndrome leading to death on Day 7. Patient blood cultures and APC cultures were both positive for Citrobacter koseri. RESULTS: The donor was a 19-year-old woman. She had previously given blood. No infectious symptom was reported during the medical interviews before and after the donation and no postdonation information was received. On the day of the donation (Day -2), her white blood cell count was 5.83 × 109 /L. She came back on Day 8 to undergo additional tests. The cultures from blood, stool, urine, the skin of the inside of the elbow at the point of needle insertion, and ear samples were all negative for C. koseri. However, a nasal sample was positive for C. koseri. CONCLUSION: The isolates from the donor's blood cultures, the APC bag, the attached tube, and the donor's nasal sample all gave identical profiles; they were thus identified as the same strain and the TTBI was confirmed.

Endocarditis caused by Streptococcus canis: an emerging zoonosis?

We report a human case of infective endocarditis caused by Streptococcus canis. Identification was carried out from positive blood culture using mass spectrometry and SodA gene sequencing. S. canis related zoonotic invasive infections may have been previously underdiagnosed due to inadequate identification of group G Streptococcus species.

Group A Escherichia coli-related purpura fulminans: an unusual manifestation due to an unusual strain?

We describe an exceptional case of life-threatening group A Escherichia coli-induced purpura fulminans. Genotyping of common polymorphisms in genes involved in innate immunity or coagulation did not reveal known susceptibility to such a manifestation. Genetic analysis of the strain revealed an unusual conserved virulence plasmidic region, pointing out its potential virulence.

Control of legionellae in a new healthcare facility following implementation of a thermal control strategy.

INTRODUCTION: The management of the Legionella risk in hospitals is essentially related to preventive measures of the hot-water supplies. AIM: To monitor the control of legionellae before and after moving to a new hospital facility. METHODS: We implemented a survey program based on the surveillance of the temperature of the hot-water supply and detection and counting of Legionella pneumophila and Legionella spp. by quantitative polymerase chain reaction and culture methods. RESULTS: Our survey program revealed that the hot-water system was colonized by L. pneumophila and Legionella spp. before the arrival of the first patients, despite the implementation of preventive measures. Thus, maintenance on the hot-water production system and subsequent cleaning and superheat disinfection of the hot-water supplies were performed, leading to the eradication of L. pneumophila reservoirs and the decrease of Legionella spp. reservoirs. No reservoirs of L. pneumophila and only rare persistent reservoirs of Legionella spp. were detected after the transfer of hospitalized patients to the new healthcare facility and during the following four years, demonstrating the effectiveness of our corrective measures, without using biocides. L. anisa was identified as the only strain of viable and cultivable Legionella spp. and was undetected during the last year. CONCLUSIONS: The strict application of our survey program before and after moving to the new hospital associated with strict implementation of corrective measures allowed us to efficiently manage the Legionella-linked risk during this period.

Prior antimicrobial therapy duration influences causative pathogens identification in ventilator-associated pneumonia.

OBJECTIVE: To determine whether prior antimicrobial therapy, divided in recent or current antibiotic treatment, influences the identification rate and/or the type of causative pathogens in patients with suspected episodes of ventilator-acquired pneumonia. DESIGN: Monocentric retrospective study. SETTING: Intensive car unit in a universitary hospital. PATIENTS: 230 episodes of ventilator-associated pneumonia with a Clinical Pulmonary Infection Score≥6 were retrospectively evaluated. Based on the antimicrobial treatment regimen, we defined 3 groups: the no antimicrobial treatment group (VAP is suspected in patients that has never received antibiotics during the last 90days), group 2: the current antimicrobial therapy (VAP is suspected under antimicrobial therapy) and group 3: the recent antimicrobial therapy (VAP is suspected whereas an antimicrobial treatment has been used during the last 90days but discontinued for >24h). INTERVENTION: Bacteriologic analysis using a protected distal sampling with microscopic examination, culture and microbial identification using MALDI-TOF. MEASUREMENTS AND MAIN RESULTS: Suspected episodes of VAP were sorted as follow: 70 suspected episodes in the no antimicrobial therapy group, 106 suspected episodes in the current antimicrobial therapy group and 54 suspected episodes in the recent antimicrobial therapy group. The rate of positive culture was significantly lower in the current antimicrobial treatment group (group 2) when compared to the recent (group 3) and to the no antimicrobial treatment groups (group 1) (42%, 68% and 86%, respectively). When compared to the recent antibiotherapy group, we observed that current antibiotherapy was significantly associated with a higher rate of MDR positive culture, mainly due to higher rate of MDR Pseudomonas aeruginosa. CONCLUSION: In patients with a high probability of VAP, current but not recent antibiotic use is associated with a lower rate of positive culture with a higher proportion of MDR pathogens, mostly MDR Pseudomonas aeruginosa.

Erysipelothrix rhusiopathiae bacteremia: a challenging diagnosis!

Erysipelothrix rhusiopathiae, a Gram-positive bacillus, is reported to cause for cutaneous infections and endocarditis. We report a case of E. rhusiopathiae bacteremia without severe clinical illness. The patient, a 74-year-old man, is suffering from a chronic lymphoid leukemia (LLC). Following a trauma, the patient developed a bruise on the left inch. Because the site of shock seemed clinically infected, oral amoxicilline-acid clavulanic (AAC) treatment was started after withdrawn 1 set of blood cultures. These blood culture specimens yielded a Gram-positive bacillus identified as E. rhusiopathiae by mass spectrometry MALDI-TOF (Microflex Brüker). The strain was sensitive to beta-lactam, fluoroquinolones and macrolides, resistant to vancomycin (natural resistance), and amikacin but sensitive to gentamicin. After 5 days of treatment by AAC, the patient became apyretic. One year after this episode, we reported no further symptoms of infection, or endocarditis. The natural resistance of E. rhusiopathiae in glycopeptides underlines the importance of a microbiological diagnosis. Indeed, vancomycine can be the treatment of first intention in Gram-positive bacillus bacteremia. The identification of bacteria using mass spectrometry is available the same day of the blood culture positivity and allows to prescribe the most adapted antibiotic treatment for the patient.

Correlation between biofilm formation and production of polysaccharide intercellular adhesin in clinical isolates of coagulase-negative staphylococci.

The ability to form a biofilm seems to play an essential role in the virulence of coagulase-negative staphylococci (CoNS) by permitting them to cause persistent prosthetic device-related infections. The most clearly characterized component of staphylococcal biofilms is the polysaccharide intercellular adhesin (PIA) encoded by the icaADBC operon. In the present paper, we assess the link between the ability to form a biofilm (Bf+/-), to synthesize PIA (PIA+/-) and the presence of the ica locus (ica+/-). For this purpose, 66 CoNS strains were tested in vitro. Seventy three percent of all strains revealed presence of the ica locus (ica+), and therefore were potentially able to produce PIA and to form a biofilm. However, the characteristics observed indicated that 15% of all strains were biofilm forming without PIA production (Bf+, PIA-, ica+/-) while 8% were PIA producers without biofilm formation (Bf-, PIA+, ica+). On the basis of the obtained data we conclude that (i) PIA synthesis alone is not sufficient to produce a biofilm and (ii) staphylococci can also form a biofilm without producing PIA.