12/111phiA Prophage Domestication Is Associated with Autoaggregation and Increased Ability to Produce Biofilm in Streptococcus agalactiae.

CC17 Streptococcus agalactiae carrying group-A prophages is increasingly responsible for neonatal infections. To investigate the impact of the genetic features of a group-A prophage, we first conducted an in silico analysis of the genome of 12/111phiA, a group-A prophage carried by a strain responsible for a bloodstream infection in a parturient. This revealed a Restriction Modification system, suggesting a prophage maintenance strategy and five ORFs of interest for the host and encoding a type II toxin antitoxin system RelB/YafQ, an endonuclease, an S-adenosylmethionine synthetase MetK, and an StrP-like adhesin. Using the WT strain cured from 12/111phiA and constructing deleted mutants for the ORFs of interest, and their complemented mutants, we demonstrated an impact of prophage features on growth characteristics, cell morphology and biofilm formation. Our findings argue in favor of 12/111phiA domestication by the host and a role of prophage features in cell autoaggregation, glycocalyx and biofilm formation. We suggest that lysogeny may promote GBS adaptation to the acid environment of the vagina, consequently colonizing and infecting neonates.

Extended-spectrum ß-lactamase-producing Enterobacteriaceae in French nursing homes: an association between high carriage rate among residents, environmental contamination, poor conformity with good hygiene practice, and putative resident-to-resident transmission.

OBJECTIVE: We evaluated the spread of multidrug-resistant Enterobacteriaceae in 38 nursing homes (NHs) in the Centre region of France. METHODS: We conducted a multicenter prevalence study and evaluated extended-spectrum ß-lactamase- and carbapenemase-producing Enterobacteriaceae (ESBLE and CPE, respectively) colonization of 1,155 residents. The colonizing isolates were studied by randomly amplified polymorphic DNA typing. We observed hygiene practices and studied the contamination of the environment in 8 NHs. RESULTS: A total of 114 residents were ESBLE carriers (9.9%); none were CPE carriers. A total of 82.6% of the ESBLE were Escherichia coli. ESBLE colonization was associated with poor health status (P = .002), malignancy (P = .006), urinary incontinence (P = .007), fecal incontinence (P = .002), previous hospitalization (P = .033), and carbapenem treatment (P = .040). The clonal relationship between isolates within NHs suggested resident-to-resident ESBLE transmission in 15 NHs. ESBLE isolates were recovered from 6 of 232 bedrooms studied. A total of 1,533 observations revealed low rates of conformity for hand hygiene (25.7%), the use of gloves (45.9%) and protective clothing (13.3%), and waste management (46.7%). Conformity rates correlated inversely with ESBLE carriage rates. CONCLUSIONS: In most of the participating NHs, improved application of standard precautions during incontinence care is needed, and greater efforts to clean the environment of residents are required.

Difficult-to-detect carbapenem-resistant IMP13-producing P. aeruginosa: experience feedback concerning a cluster of urinary tract infections at a surgical clinic in France.

BACKGROUND: We report a carbapenem-resistant P. aeruginosa clone responsible for a cluster of urinary tract infections in elderly surgery patients, diagnosed during a three-month period in a 59-bed surgical clinic. FINDINGS: The clonal nature of the cluster was established by molecular study of the P. aeruginosa isolates (PFGE and MLST). Despite an MIC of imipenem in the susceptibility range for two isolates, all were metallo-ß-lactamase-producers (IMP13-type, clone ST621). We conducted a review of the medical and surgical procedures. We tested water delivered into the clinic and urological devices for the presence of the epidemic strain. The hygiene nurse observed hygiene practices. A week after the implementation of barrier precautions around the fourth infected patient, we studied the extent to which the patients hospitalised were colonised to assess whether the spread of the epidemic strain had been controlled. CONCLUSIONS: 1/ Our findings indicate the difficulties in the detection of the metallo-ß-lactamase in this clone, that resulted in the alert being delayed. 2/ Unlike most investigations of UTI outbreaks described in urology wards, we did not detect any contaminated urological devices or water colonisation. 3/ Consistent with outbreaks involving the IMP-13 clone in critical care units, the observation of inadequate application of standard precautions argued for patient-to-patient transmission during urinary management of the urology patients. 4/ The implementation of barrier precautions around infected patients resulted in control of the spread of the epidemic clone. This report serves as an alert concerning a difficult-to-detect multidrug-resistant P. aeruginosa clone in elderly urology patients.

Effect of hydroxyapatite coating and polymethylmethacrylate on stainless steel implant-site infection with Staphylococcus epidermidis in a sheep model.

We aimed to study the influence of hydroxyapatite (HA) coating and polymethylmethacrylate (PMMA) cement on the risk of development of stainless steel implant-site infection with Staphylococcus epidermidis in a sheep model. Uncoated, HA-coated, and PMMA-cemented stainless steel implants were inserted in the left femur of 30 sheep. For each type of implant, sheep were inoculated with S. epidermidis in the intramedullary canal and one non-inoculated group was used as control. After 6 weeks, infection was evaluated using clinical, radiological, bacteriological, and histological criteria. Radiological and clinical results were normal. Cultures were negative in the control sheep. In the inoculated sheep, interposition tissue and bone cultures were positive in 2 of 6 uncoated, 6 of 6 HA, and 6 of 6 PMMA implants with a mean bacteria count of 5.2 +/- 1.17, 3.5 +/- 0.7, and 3.9 +/- 0.9 log10 cfu/g, respectively (NS), for interposition tissue, and 4 +/- 0.01, 2.9 +/- 0.6, and 2.5 +/- 1.3 log10 cfu/g, respectively (NS) for bone. The polymorphonuclear leukocyte (PMN) score (mean number of PMN per 10 different microscopic high-power fields >or=5) in interposition tissue was >or=3 in 6 of 6 HA, significantly different from uncoated (3 of 6) and PMMA (2 of 6) groups (p = 0.04). The HA and PMMA inoculated groups had a higher infection rate than the uncoated inoculated group (p = 0.06). In this experimental sheep model of S. epidermidis infection at the bone-biomaterial interface, HA seems to be at higher risk of infection compared with uncoated or PMMA-cemented stainless steel, when inoculation is intramedullary and contemporary with implantation.

Nasal carriage of methicillin-resistant staphylococcus aureus in vascular surgery.

The purpose of this study was to determine the prevalence of nasal carriage of methicillin-resistant Staphylococcus aureus (MRSA) and to define risk factors allowing identification of high-risk patients for MRSA nasal carriage at admission to the vascular surgery unit. From March 23, 2004 to July 13, 2004, screening for nasal carriage of MRSA was conducted at admission to the vascular surgery unit and 1 week thereafter. To analyze risk factors for MRSA nasal carriage at admission to the vascular surgery unit, a case-control study was carried out in patients presenting colonization at the time of admission. A total of 308 patients underwent nasal screening for MRSA. Thirteen were colonized with MRSA (nine at admission and four acquired), i.e., 4.2% of patients. Methicillin-susceptible Staphylococcus aureus (MSSA) was found in 11.4% of patients who underwent screening. Six patients with MRSA infection were identified during the study period. The two patients who acquired infection were colonized at the time of admission. Arrival from another health-care facility and from another department was a significant risk factor for carriage of MRSA. The prevalence of nasal carriage in vascular surgery was 4.2%. Nasal screening is highly cost-effective since 60% of MRSA carriers were undetected using diagnostic specimens alone. French recommendations issued for cardiac and orthopedic surgery by the consensus conference on preoperative management of infectious risk on March 5, 2004, should be extended to vascular surgery.

Virulence and cord blood mononuclear cells cytokine production induced by perinatal listeria monocytogenes strains from different phylogenetic lineages.

Some of the phylogenetic lineages of Listeria monocytogenes are more likely to cause invasive disease in humans than are strains from other phylogenetic lineages. This suggests that strains belonging to these lineages display different levels of pathogenicity. To investigate this, we carried out a plaque-forming assay with HT-29 cells to evaluate the virulence of six perinatal strains from the three lineages that compose the species. All of the strains were largely over the 3.34 cutoff (between 4.29 and 5.97 mean log) with the HT-29 model and can therefore be considered to be equally virulent. We also explored part of the immune response of cord blood mononuclear cells by measuring cytokine production. All strains induced the production of similar amounts of TNF-alpha and IL-1beta. High concentrations of IL-6 and IL-8 were produced (between 6,000 and 17,000 pg/ml), whereas little or no IFN-gamma or IL-12 was produced. Thus, there is no difference between the strains from the three genetic lineages in terms of virulence or cytokine response. Given the epidemiological distribution of the serotypes responsible for human listeriosis and the genetic structure of the L. monocytogenes species, our results suggest: (i) that all strains from lineage I (serotypes 1/2b and 4b), a genetically homogeneous subpopulation, have a similar level of pathogenicity, and (ii) that lineage II (serotypes 1/2a and 1/2c), which is genetically more heterogeneous, is composed of strains with different levels of pathogenicity. The ones responsible for invasive diseases, particularly perinatal infections, display a similar level of pathogenicity to lineage-I strains and are not virulence-attenuated strains that can only infect the most immunocompromised hosts, whereas the other lineage-II strains are probably less pathogenic for humans.

Genetic features of Pseudomonas aeruginosa isolates from cystic fibrosis patients compared with those of isolates from other origins.

In order to improve our understanding of the colonization of the pulmonary tract of cystic fibrosis (CF) patients by Pseudomonas aeruginosa, 162 isolates from five different ecological origins were studied. The genetic features of each isolate were determined by random amplification of polymorphic DNA (RAPD) and by searching for eight virulence genes (six known virulence genes, algD, lasB, toxA, plcH, plcN and exoS, and two genes encoding putative neuraminidases, nan1 and nan2). Five RAPD groups were identified. Most of the CF isolates were distributed equally in three of these groups (RA, RB and RC). The CF isolates in RB were related to isolates from a wide variety of origins. The CF isolates in RA were related to a population composed of 65 % of the non-CF isolates from pulmonary tract infections. RC was mainly composed of CF isolates that were related to 30 % of isolates from plants. All genes except exoS and nan1 were present in all isolates. The exoS and nan1 virulence factor genes were most prevalent in CF isolates. exoS, which encodes exoenzyme S, was present in 94 % of CF isolates but also in 80 % of non-CF isolates from pulmonary tract infections. nan1, which encodes a putative neuraminidase, was found in 82.5 % of the isolates from group RC, which was composed largely of CF isolates. In conclusion, three major genogroups of P. aeruginosa isolates, each of which exhibits peculiar genetic features, are able to colonize CF patients. This may have different consequences on the outcome of pulmonary disease.

Enzyme polymorphism in Pseudomonas aeruginosa strains recovered from cystic fibrosis patients in France.

Each of 314 strains of Pseudomonas aeruginosa recovered from 87 French cystic fibrosis (CF) patients was typed by multilocus enzyme electrophoresis to investigate the genetic diversity, the relatedness and the molecular epidemiology of strains isolated from cases of chronic pulmonary colonization. Comparison of allele profiles at 18 enzyme loci identified 17 electrophoretic types (ETs). Of the 314 isolates, 290 (92%) were either ET1 (n = 127) or ET2 (n = 163), which differed only at the shikimate dehydrogenase (SKD) locus. The mean genetic diversity (H) was 0.138. These results suggest that there is cross-colonization between patients and/or that two predominant groups of strains are able to colonize French CF patients. Sequential isolates collected from 18 patients during a period of 12-28 months were analysed to assess genomic variability and its relationship to clinical outcome. Six patients were colonized by a stable strain. For the others, double infections or changes in colonization over time were observed. No relationships were detected between the clinical outcome and the persistence of stable isolates, the emergence of transient superinfecting variants, the presence of multiple ETs or the shift of ET during the monitoring.