Faecal carriage of oxyiminocephalosporin-resistant Enterobacteriaceae among paediatric units in different hospitals in the south of France.

The aim of this study was to determine the presence of oxyiminocephalosporin-resistant (OCR) Gram-negative bacilli and extended-spectrum ß-lactamase (ESBL)-producing isolates in stool specimens obtained from paediatric patients hospitalised for acute diarrhoea. We conducted a prospective, multicentre study over a period of 6 months in seven hospitals in the south of France. Samplings were carried out from infants admitted for acute diarrhoea with no previous antibiotic treatment in the last week. Bacteria in stool specimens were screened for the presence of OCR Gram-negative bacilli on Drigalski agar supplemented with ceftazidime and ESBL CHROMagar® media, and confirmed by the Rosco tablets test. Genetic detection was performed by the Check MDR® microarray and by polymerase chain reaction (PCR) and sequencing with bacterial DNA extracted from isolates. The presence of OCR enterobacteria was markedly high (177/1,118 patients, 15.2 %), with an important community origin (66.1 %). The majority of multidrug-resistant (MDR) bacteria were Enterobacter cloacae (106, 59.9 %) and Escherichia coli (61, 34.5 %). The prevalence of ESBL and CTX-M producers represented 5.2 and 4.3 % of the isolates, respectively. The main proportion of these ESBL carriers was found in children less than 1 year of age (53.4 %). One carbapenemase (IMP-1) was detected. The study revealed the wide dissemination of MDR bacteria in infants attending hospitals in the south of France during a non-outbreak situation, in particular, the spread of cefotaximase and the detection of a carbapenemase. This worrisome situation must reinforce the use of hygiene procedures and appropriate antibiotics to control the emergence and spread of OCR organisms.

Membrane permeability, a pivotal function involved in antibiotic resistance and virulence in Enterobacter aerogenes clinical isolates.

Imipenem-susceptible E. aerogenes isolates exhibiting extended spectrum ß-lactamases, target mutations and a basal efflux expression, were identified in five patients. After imipenem treatment, imipenem-intermediate susceptible (IMI-I) or resistant (IMI-R) isolates emerged in these patients. Alteration in porin synthesis and increase in efflux expression were observed in the IMI-I isolates whereas complete loss of the porins, LPS alteration and efflux overexpression were observed in the IMI-R isolates. Bacterial virulence of the strains was investigated by the Caenorhabditis elegans model. The IMI-R isolates were shown to be significantly less virulent than the IMI-susceptible or IMI-I isolates. The pleiotropic membrane alteration and its associated fitness burden exhibited by E. aerogenes isolates influence their antibiotic resistance and their virulence behaviour. These findings highlight the balance between the low permeability-related resistance and virulence and their relationships with the treatment of resistant pathogens.

Beneficial effects of implementing guidelines on microbiology and costs of infected diabetic foot ulcers.

AIMS/HYPOTHESIS: In 2003, guidelines for management of diabetic foot infection (DFI) were written by the authors' team according to the guidelines of the International Working Group on the Diabetic Foot. The effects of implementing these guidelines on the microbiology and costs of infected diabetic foot ulcers were assessed. METHODS: From 2003 to 2007, potential beneficial effects of implementing these guidelines were assessed by comparison over time of bacteriological data (number of bacterial samples, number of microorganisms isolated in cultures, prevalence of multidrug-resistant organisms [MDRO] and colonising flora), and costs related to use of antimicrobial agents and microbiology laboratory workload. RESULTS: The study included 405 consecutive diabetic patients referred to the Diabetic Foot Unit for a suspected DFI. From 2003 to 2007, a significant decrease was observed in the median number of bacteria species per sample (from 4.1 to 1.6), prevalence of MDRO (35.2% vs 16.3%) and methicillin-resistant Staphylococcus aureus (52.2% vs 18.9%) (p < 0.001). Moreover, prevalence of pathogens considered as colonisers dramatically fell from 23.1% to 5.8% of all isolates (p < 0.001). In parallel, implementation of guidelines was associated with a saving of euro14,914 (US$20,046) related to a reduced microbiology laboratory workload and euro109,305 (US$147,536) due to reduced prescription of extended-spectrum antibiotic agents. CONCLUSIONS/INTERPRETATION: Implementation of guidelines for obtaining specimens for culture from patients with DFI is cost-saving and provides interesting quality indicators in the global management of DFI.

[Evolution of antimicrobial resistance against Pseudomonas aeruginosa in a French university hospital between 2002 and 2006]. / Evolution de la résistance aux antibiotiques de Pseudomonas aeruginosa dans un centre hospitalier universitaire entre 2002 et 2006.

AIM OF STUDY: Monitor evolution of antibiotic resistance of Pseudomonas aeruginosa from 2002 to 2006 in our hospital to optimize antibiotherapy. PATIENTS AND METHOD: The infections/colonizations with P. aeruginosa have been identified by the hospital's informatic database. Bacteriological samples realized 48hours after patient's admission was considered as nosocomial. A Cochran-Armitage test was conducted to assess the evolution of resistance. RESULTS: During this period, 2098 infections/colonizations with P. aeruginosa have been identified. Bacteriological samples (68.5%) were nosocomial. Among the beta-lactam antibiotics, ceftazidime and imipenem were the most active (R=16.8% and 15.2%, respectively), followed by piperacillin and piperacillin-tazobactam (R=24.8%, 18.4%, respectively). Amikacin and tobramycin were more active than gentamicin (R=19.9%; 22.2% and 40.6%, respectively). 28.9% of strains were resistant to ciprofloxacin. Nosocomial strains were significantly more resistant than non-hospital strains: ceftazidime: 17.9% versus 14.2%, p=0.0346; ticarcillin-clavulanic acid: 47.5% versus 39.6%, p=0.0009; piperacillin-tazobactam: 20.0% versus 14.8%, p=0.0046; ciprofloxacin: 30.7% versus 25.2%, p=0.0112. A significant increase in the resistance of nosocomial strains to ceftazidime, ticarcillin-clavulanic acid and piperacillin-tazobactam was noted. Resistance from non-hospital strains to fluoroquinolones, aminoglycosides, ceftazidime, piperacillin and ticarcillin-clavulanic acid decreased significantly. CONCLUSION: P. aeruginosa is a predominantly nosocomial microorganism. There is a decrease of resistance for non-hospital strains. But the resistance of nosocomial strains to antibiotics widely prescribed in hospital is worrying.

[In vitro activity of daptomycin against strains isolated from diabetic foot ulcers]. / Activité in vitro de la daptomycine vis-à-vis de souches cliniques isolées de plaies du pied chez des diabétiques.

PURPOSE OF THE STUDY: The aim of this study was to evaluate the in vitro activity of daptomycin and other comparator agents against bacterial strains isolated from diabetic foot infections (DFI). PATIENTS AND METHODS: All diabetic patients hospitalized for a first episode of DFI (stage 2 to 4, according to the International Working Group of Diabetic Foot classification) were selected in Nîmes University hospital between June 2006 to August 2007. MIC were determined using E-test strip (AB Biodisk) and custom broth microdilution panels against bacterial strains isolated from foot samples. RESULTS: Two hundred strains were studied. Daptomycin was active against 99.5% of all the strains especially Streptococcus sp. (100%), Enterococcus sp. (100%), coagulase-negative Staphylococcus (100%) and methicillin-susceptible Staphylococcus aureus (100%). Exclusively, one methicillin-resistant S. aureus strain was not covered by this antibiotic. CONCLUSIONS: Daptomycin, a new broad spectrum antimicrobial agent against Gram-positive cocci, is qualified to belong to the therapeutic arsenal package of complicated skin and soft tissue infections in diabetic patients after microbial documentation.

[In vitro activity of ertapenem against strains isolated from diabetic foot infections]. / Activité in vitro de l'ertapénème vis-à-vis de souches bactériennes isolées de plaies infectées du pied chez des patients diabétiques.

OBJECTIVE: The authors aimed to evaluate the in vitro activity of ertapenem against bacterial strains isolated from diabetic foot infections (DFI). METHODOLOGY: All diabetic patients hospitalized for a first episode of DFI (stages 2 to 4, according to the International Working Group of Diabetic Foot Classification) were selected in the Nîmes University hospital between January 2005 to December 2005. MICs were determined using both E-test strips and dilution methods on bacterial strains isolated from foot samples. RESULTS: Two hundred and fifty-two bacteria (154 Gram-positive cocci including 94 Staphylococcus aureus, 80 Gram-negative bacilli with 56 Enterobacteriaceae, and 18 anaerobes) were studied. Ertapenem was active against all Streptococcus spp., Enterobacteriaceae, anaerobes, and also against 89.8% of methicillin-susceptible S. aureus isolates. However, this antibiotic was active only against 31.5% of Staphylococcus epidermidis, 21.8% of Enterococcus faecalis, and 15.8% of Pseudomonas aeruginosa. CONCLUSION: Our results indicate that ertapenem may be a useful agent to treat patients suffering from DFI after bacterial identification.

In vitro activity of tigecycline against strains isolated from diabetic foot ulcers.

PURPOSE OF THE STUDY: The aim of this study was to evaluate the in vitro activity of tigecycline and other comparator agents against bacterial strains isolated from diabetic foot infections (DFI). PATIENTS AND METHODS: All diabetic patients hospitalized for a first episode of DFI (stage 2 to 4, according to the International Working Group of Diabetic Foot classification) were selected in Nîmes University hospital between January 2005 and June 2006. MICs were determined using custom broth microdilution panels against bacterial strains isolated from foot samples. RESULTS: Three hundred fifteen strains were studied. Tigecycline was active against 83.7% of all the strains especially Gram-positive cocci (97.3%) in particular methicillin-resistant Staphylococcus aureus (96%), Enterobacteriaceae (88.5%) and anaerobes (100%). Exclusively Pseudomonas aeruginosa and Proteae were not covered by this antibiotic. CONCLUSIONS: Tigecycline, a new broad spectrum antimicrobial agent, is qualified to belong to the therapeutic arsenal package of complicated skin and soft tissue infections in diabetic patients after microbial documentation.

Virulence genotype and nematode-killing properties of extra-intestinal Escherichia coli producing CTX-M beta-lactamases.

This study evaluated the virulence potential of Escherichia coli isolates producing CTX-M beta-lactamases. During a 24-month period, 33 extended-spectrum beta-lactamase (ESBL)-producing E. coli, including 14 CTX-M-producers, were isolated from urinary tract infections at Nîmes University Hospital, France. The prevalence of 14 major virulence factors (VFs) was investigated by PCR and compared with the prevalence in a group of 99 susceptible E. coli isolates. Ten VFs were less prevalent (p <0.05) in the ESBL isolates than the susceptible E. coli, while iutA and traT were more prevalent in ESBL isolates (p <0.05). Moreover, the CTX-M-producing isolates had significantly fewer VFs than TEM-producing isolates. A novel infection model using the nematode Caenorhabditis elegans was developed to assess the virulence properties of extra-intestinal pathogenic E. coli (ExPEC) strains in vivo. C. elegans infection assays, using 14 ESBL-producing E. coli and ten susceptible E. coli isolates, indicated that the ability to kill nematodes correlated with the presence of VFs, and that CTX-M-producing isolates had relatively low virulence in vivo. Overall, the results suggested that hospital-acquired CTX-M-producing E. coli, although adapted for survival in an antibiotic-rich environment such as the hospital milieu, have a relatively low intrinsic virulence potential.

[Antimicrobial susceptibility of Proteus mirabilis urinary tract isolates from 1999 to 2005 at Nîmes University Hospital]. / Profils de résistance des souches urinaires de Proteus mirabilis de 1999 à 2005 au CHU de Nîmes.

AIM OF THE STUDY: To analyse antimicrobial resistance trends of Proteus mirabilis urinary tract isolates from 1999 to 2005 at the Nîmes University hospital. MATERIALS AND METHODS: We retrospectively collected non-duplicate urinary tract infections and colonization isolates from inpatients between 1 January 1999 and 31 December 2005. RESULTS: One thousand and eight non-duplicate urinary tract isolates were studied, 63.1% were from females and the mean age was 76 years. The mean resistance rate was 59.0% for amoxicillin (AMX), 48.0% for piperacillin (PIP), 3.9% for cefotaxim, 33.9% for amoxicillin plus clavulanic acid (AMC) and 2.8% for piperacillin plus tazobactam (TZP). A significant increase in resistance was observed for AMC and TZP. The mean resistance rate was 35.0% for norfloxacin, 34.8% for ofloxacin and 23.5% for ciprofloxacin. No significant increase in resistance to fluoroquinolones was seen except for ciprofloxacin whereas a significant increase was observed for aminoglycosides. The mean rate resistance for cotrimoxazole was 33.2% with a significant decrease in the resistance during the study period. CONCLUSION: P. mirabilis stilled sensitive to cefotaxim or ceftazidim and to TZP. The significant increase in the rate resistance to AMC and TZP could be explained by production of beta-lactamases and in particular extended-spectrum beta-lactamases. The increase in resistance observed for fluoroquinolones become a major concern. Amikacine was the most active aminoglycosides. These data suggested for the re-enforcement of the antimicrobial susceptibility surveillance in order to optimise the rational use of antibiotics.

Risk factors for multidrug-resistant Pseudomonas aeruginosa nosocomial infection.

A case-control study was conducted in a university hospital to determine the risk factors for nosocomial infection with multidrug-resistant Pseudomonas aeruginosa (MDR-PA) among all hospitalized patients and among those with a nosocomial infection due to P. aeruginosa. Eighty patients infected with MDR-PA, 75 infected with a non-MDR phenotype and 240 random controls were included in the 12-month study. Among all hospitalized patients, age, severity index, having a bedridden condition, transfer from other units, nasogastric feeding, urinary catheterization and exposure to beta-lactams (OR=2.5) or fluoroquinolones (OR=4.1) in the seven days before infection were linked to nosocomial infection due to MDR-PA. Among patients infected by P. aeruginosa, exposure to fluoroquinolones (OR=4.7) or surgery (OR=0.5) were linked to the isolation of MDR-PA. This study showed that, in addition to urinary catheterization, nasogastric feeding is an important risk factor in MDR-PA infection. Indeed, an imbalance in gut flora, modifications to the mucous membranes due to the use of nasogastric feeding and the selection pressures exerted by antibiotics were implicated in the occurrence of this infection.

Epidemiological study by pulsed-field gel electrophoresis of an outbreak of extended-spectrum beta-lactamase-producing Klebsiella pneumoniae in a geriatric hospital.

Twelve cases of infections caused by extended-spectrum beta-lactamase (ESBla)-producing Klebsiella pneumoniae were reported between August 1991 and March 1993 in the Geriatric Department of the Nimes University Hospital, where these bacterial had not been previously isolated. Restriction profiles of total genomic DNAs cleaved by XbaI and SpeI were compared by pulsed-field gel electrophoresis. The strains that were tested included the 12 isolates from K. pneumoniae-infected patients, strains recovered from rectal swabs of asymptomatic patients in the same ward, and strains isolated in other hospitals in Nîmes at the same time. The restriction profiles of the 12 isolates and those recovered from asymptomatic patients in the same ward were very similar. Over a period of more than 1 year, extended-spectrum beta-lactamases were not detected in K. pneumoniae isolates with restriction patterns different from that of the epidemic strain. It seems, therefore, that there was no transfer of a plasmid or a gene coding for ESBla to strains of K. pneumoniae that were different from the epidemic strain. At the same time, ESBla-producing K. pneumoniae isolates exhibiting restriction endonuclease profiles very different from that of the epidemic strain were isolated from other hospitals in Nîmes. None of these strains caused an outbreak. Pulsed-field gel electrophoresis, which allows precise characterization of strains beyond the species level, is a useful tool for studying the ESBla-producing K. pneumoniae strains involved in nosocomial outbreaks.

DNA polymorphisms in methicillin-susceptible and methicillin-resistant strains of Staphylococcus aureus.

Restriction fragment length polymorphisms in methicillin-susceptible and methicillin-resistant (MRSA) strains of Staphylococcus aureus isolated in the same hospital over a 4-month period were studied by using SmaI and ApaI digestion of genomic DNA and pulsed-field gel electrophoresis. Each of the 20 methicillin-susceptible strains had a unique SmaI pattern, but the 27 MRSA strains showed only seven SmaI patterns. More than half of the SmaI fragments in all of these seven patterns were identical, as were those in the patterns from two unrelated MRSA strains. Digestion with ApaI, which cuts staphylococcus DNA into at least twice as many fragments, confirmed the results obtained with SmaI. Lastly, the plasmid contents of MRSA strains showing identical SmaI and ApaI electrophoretic patterns were not identical. These results are interpreted as supporting the hypothesis that all MRSA strains arose from a single clone and emphasize the need to use several methods in epidemiological investigations of MRSA outbreaks.

Use of pulsed-field gel electrophoresis for investigation of hospital outbreaks of Acinetobacter baumannii.

Genomic DNAs from taxonomically and epidemiologically well-defined strains of Acinetobacter baumannii were digested with restriction endonucleases that cleave with low frequency, and the fragments were separated by pulse-field gel electrophoresis. Restriction fragment length polymorphisms were observed. Restriction fragment length polymorphism analysis can be used as an epidemiological tool to delineate outbreaks of nosocomial infections caused by A. baumannii.

Teicoplanin treatment of alkaline encrusted cystitis due to Corynebacterium group D2.

Alkaline-encrusted cystitis (AEC) is a chronic inflammation of the bladder related to the gram-positive bacillus Corynebacterium Group D2. This germ is often resistant to many antibiotics and is particularly difficult to eradicate in the particular setting of AEC. The authors report two observations of AEC treated with the glycopeptid antibiotic teicoplanin, which led to permanent cure of AEC.

[A severe epidemic of Streptococcus group G infection in hemodialysis: epidemiologic survey by molecular biology and preventive measures]. / Epidémie d'infection sévère à streptocoque G en hémodialyse: enquête épidémiologique par biologie moléculaire et mesure préventive.

An outbreak of group G streptococci infection affected 6 patients of an hemodialysis unit. Group G streptococci were isolated from patients and from numerous atmospheric specimens, different parts of two dialysis machines, and two blankets, but from only one nurse on the hospital staff. Typing of group G streptococci by an improved method of DNA fingerprinting showed that the isolates from one patient, the nurse and the two blankets differed from one another. The group G streptococci were probably transmitted to patients by dialysis machines with defective microporous filters. No further case of group G streptococci infection was reported three years later since microporous guard filters were systematically doubled.

Use of low-frequency-cleavage restriction endonucleases for DNA analysis in epidemiological investigations of nosocomial bacterial infections.

Epidemiological investigations of bacterial infections are generally based on multiple phenotypic markers that are often difficult to verify. A more general and reliable method is genomic DNA analysis by restriction endonucleases. However, the commonly used endonucleases produce too many fragments for correct separation by agarose electrophoresis. In contrast, simple electrophoretic patterns are obtained after genomic DNA digestion by low-frequency-cleavage restriction endonucleases and pulsed-field gel electrophoresis, making it easier to compare numerous strains from the same species. This technique was used to investigate an Acinetobacter calcoaceticus outbreak in a urologic department and bronchial colonization of artificially ventilated patients by Pseudomonas aeruginosa in an intensive care unit. The method allowed a clear distinction between epidemic and self-contaminating strains in these different epidemiological situations.

[Pneumococcal pneumonia and septic shock in the newborn infant]. / Pneumopathie et choc septique à pneumocoque chez le nouveau-né.

Pneumococcal sepsis and pneumonia in the neonate are rarely reported. They appear either as an early-onset respiratory distress with a high mortality rate or as a delayed infection. The authors describe 3 term neonates with an early respiratory distress syndrome and recall the main points of this severe foeto-maternal infection. Neonatal pneumococcal sepsis is strikingly similar to early-onset group B streptococcal infection. The isolation of the germ in the mother's vaginal flora is hazardous. Such cases suggest that early respiratory support and intensive circulatory resuscitation lead only to a slight decrease in the mortality rate, and thus preventive antibiotherapy is a necessity.