Clinical and microbiological determinants of severe and fatal outcomes in patients infected with Enterobacteriaceae producing extended-spectrum ß-lactamase.

Although extended-spectrum ß-lactamase (ESBL)-producing Enterobacteriaceae have become a worldwide public health concern, little is known regarding the clinical course of colonized or infected individuals. Our objective was to characterize the determinants of fatal outcomes related to ESBL-producing microorganisms at a large hospital in Paris, France. In 2012-2013, all consecutive patients with clinical samples testing positive for ESBL-producing Enterobacteriaceae at Saint-Antoine Hospital were identified. Patient clinical data were obtained at hospital entry, while information on intensive care unit (ICU) admissions and death were prospectively collected. Risk-factors for fatal 1-year outcomes were assessed using logistic regression. In total, 643/4684 (13%) ESBL-positive samples were observed, corresponding to 516 episodes (n = 206, 40% treated) among 330 patients. Most episodes were nosocomial-related (n = 347/516, 67%) involving Escherichia coli (n = 232/516, 45%) or Klebsiella pneumoniae (n = 164/516, 32%). Empirical antibiotic therapy was adequate in 89/206 (43%) infections, while the median length of hospital stay was 30 days [interquartile range (IQR) = 11-55] and 39/201 (19%) were admitted to the ICU. Overall, 104/241 patients (43%) with available data died within 1 year. In the multivariable analysis, 1-year death was associated with age >80 years (p = 0.01), concomitant comorbidity (p = 0.001), nosocomial-acquired infection (p = 0.002), and being infected rather than colonized (p < 0.001). In this series of patients with identified samples of ESBL-producing Enterobacteriaceae, hospital burden was large and 1-year mortality rates high. Understanding which patients in this setting would benefit from broad-spectrum empirical antibiotic therapy should be further examined.

Possible importation and subsequent cross-transmission of OXA-48-producing Klebsiella pneumoniae, France, 2010.

We report the possible first patient-to-patient transmission of Klebsiella pneumoniae with decreased susceptibility to imipenem and producing OXA-48, CTX-M15, TEM-1 and OXA-1 in a French hospital.

Extended measures for controlling an outbreak of VIM-1 producing imipenem-resistant Klebsiella pneumoniae in a liver transplant centre in France, 2003-2004.

We report the successful control of an outbreak caused by imipenem-resistant VIM-1-producing Klebsiella pneumoniae (IR-Kp) in France. This outbreak occurred in a care centre for abdominal surgery that includes a 15-bed liver intensive care unit and performs more than 130 liver transplantations per year. The index case was a patient with acute liver failure transferred from a hospital in Greece for urgent liver transplantation who was carrying IR-Kp at admission as revealed by routine culture of a rectal swab. Infection control measures were undertaken and included contact isolation and promotion of hand hygiene with alcohol-based hand rub solution. Nevertheless, secondary IR-Kp cases were identified during the six following months from 3 December 2003 to 2 June 2004. From 2 June to 21 October, extended infection control measures were set up, such as cohorting IR-Kp carriers, contact patients and new patients in distinct sections with dedicated staff, limiting ward admission, and strict control of patient transfer. They led to a rapid control of the outbreak. The global attack rate of the IR-Kp outbreak was 2.5%, 13% in liver transplant patients and 0.4% in the other patients in the care centre (p<0.005). Systematic screening for IR-Kp of all patients admitted to the care centre is still maintained to date and no secondary IR-Kp case has been detected since 2 June 2004.

Genetic context of plasmid-carried blaCMY-2-like genes in Enterobacteriaceae.

Analysis of 15 European clinical Enterobacteriaceae isolates showed that differences in the genetic context of blaCMY-2-like genes reflected the replicon type, usually IncA/C or IncI1. These blaCMY-2 loci may originate from the same ISEcp1-mediated mobilization from the Citrobacter freundii chromosome as structures described in earlier studies.

Partition locus-based classification of selected plasmids in Klebsiella pneumoniae, Escherichia coli and Salmonella enterica spp.: an additional tool.

The dissemination of antimicrobial resistance genes in Enterobacteriaceae has been largely attributed to plasmids, circular DNA molecules capable of autonomous replication. Whereas high-copy-number plasmids primarily rely on passive diffusion for plasmid maintenance, low-copy-number plasmids utilize so-called partition (par) systems. Plasmid partition relies on three structures, i.e. a centromere like DNA site, a centromere-binding protein and an ATPase or a GTPase motor protein for plasmid positioning. Identification and classification of plasmids is essential for tracing plasmids conferring drug resistance. PCR-based replicon typing is currently the standard method for plasmid identification but there are new classification schemes, especially the relaxase gene typing (PRaseT). Here we developed a multiplex PCR set targeting par loci found on the plasmids most frequently encountered in Enterobacteriaceae. This method, called "plasmid partition gene typing" (PAR-T), was validated with 136 transconjugants or transformants harboring various replicon types. The method was tested with 30 multidrug-resistant clinical isolates including Escherichia coli, Klebsiella pneumoniae and Salmonella enterica subsp. enterica carrying 1-4 replicons; all replicons were tested in parallel with PRaseT for comparison. Six multiplex PCRs and one simplex PCR including 18 pairs of primers recognized plasmids of groups IncA/C, FIA, FIB, FIC, FIIk, FII, HI1, HI2, I1, L/M, N, X. Our set of multiplex PCRs showed high specificity for the classification of resistance plasmids except for IncX replicons.

Identification of a Clostridium cocleatum strain involved in an anti-Clostridium difficile barrier effect and determination of its mucin-degrading enzymes.

We isolated Gram-positive circular bacterium HB1 from intestinal microflora showing resistance to colonization by Clostridium difficile in mice (Su et. al., 1986a,b). We studied its enzymatic capacity to degrade mucin the first potential barrier to implantation of strains in the intestine. Its biochemical characteristics, terminal metabolites and the electrophoretic profiles of proteins and DNA-DNA homology indicated that it was a strain of Clostridium cocleatum. This strain displayed numerous glucosidase activities which were assumed to play a role in the degradation of mucin oligosaccharide chains in the digestive tract. These enzymes included alpha- and beta-galactosidases, beta-glucosidase, beta-N-acetylglucosaminidase, sialidase and alpha-N-acetylgalactosaminidase.

Cardiac abscess following percutaneous transluminal coronary angioplasty.

We report the first case of myocardial abscess directly related to percutaneous transluminal angioplasty (PTCA). Infectious complications of PTCA are very rare and limited to a few cases of groin infection and septic endarteritis most often after repeated procedures. In our patient, a problematic and repeated procedure probably led to a direct colonization and subsequent infection of an intimal dissection of the right coronary artery. Standard aseptic techniques can be inadequate in the case of early repuncture or if there is an indwelling line. Prophylactic antibiotic treatment should be considered in this case, although its usefulness has not been yet formally demonstrated.

An outbreak of imipenem-resistant Acinetobacter baumannii in critically ill surgical patients.

OBJECTIVE: To describe an outbreak of imipenem-resistant Acinetobacter baumannii (IR-Ab) and the measures for its control, and to investigate risk factors for IR-Ab acquisition. DESIGN: An observational and a case-control study. SETTING: A surgical intensive care unit (ICU) in a university tertiary care hospital. METHODS: After admission to the ICU of an IR-Ab-positive patient, patients were prospectively screened for IR-Ab carriage upon admission and then once a week. Environmental cleaning and barrier safety measures were used for IR-Ab carriers. A case-control study was performed to identify factors associated with IR-Ab acquisition. Cases were patients who acquired IR-Ab. Controls were patients who were hospitalized in the ICU at the same time as cases and were exposed to IR-Ab for a similar duration as cases. The following variables were investigated as potential risk factors: baseline characteristics, scores for severity of illness and therapeutic intervention, presence and duration of invasive procedures, and antimicrobial administration. RESULTS: Beginning in May 1996, the outbreak involved 17 patients over 9 months, of whom 12 acquired IR-Ab (cases), 4 had IR-Ab isolates on admission to the ICU, and 1 could not be classified. Genotypic analysis identified two different IR-Ab isolates, responsible for three clusters. Ten of the 12 nosocomial cases developed infection. Control measures included reinforcement of barrier safety measures, limitation of the number of admissions, and thorough environmental cleaning. No new case was identified after January 1997. Eleven of the 12 cases could be compared to 19 controls. After adjustment for severity of illness, a high individual therapeutic intervention score appeared to be a risk factor for IR-Ab acquisition. CONCLUSION: The outbreak ended after strict application of control measures. Our results suggest that high work load contributes to IR-Ab acquisition.

Molecular characterisation by PCR-restriction fragment length polymorphism of TEM beta-lactamases.

To rapidly characterise TEM-derived extended-spectrum beta-lactamases a fast and easy method using polymerase chain reaction-restriction fragment length polymorphism was developed. This method was validated with ten reference TEM-type extended-spectrum beta-lactamases. The mutations involved in TEM-20 and TEM-21, which were previously reported only with biochemical analysis, were then characterised. TEM-20 differed from TEM-19 by a silent mutation at position 925 (A for G), and TEM-21 differed from TEM-3 and TEM-14 by a single mutation (G for A) in an unreported position 660. beta-lactamase conferring low resistance to ceftazidime (TEM-29), was described. TEM-29 derived from TEM-1, with an amino acid substitution, his-164. Finally, the combination of polymerase chain reaction-restriction fragment length polymorphism and plasmid analysis allowed us to investigate nosocomial outbreaks due to clinical isolates of multi-resistant Klebsiella pneumoniae in three hospitals.

[Beta-lactamase inhibitors]. / Les inhibiteurs des beta-lactamases.

UNLABELLED: BETA-LACTAMASE: The capacity to produce beta-lactamase, an enzyme which hydrolyses penicillin and cephalosporines, is the main source of bacterial resistance to beta-lactamines, thus the important contribution of beta-lactamase inhibitors (clavanulanic acid, sulbactam and tazobactam). MECHANISM OF ACTION: Beta-lactamase inhibitors inactivate these enzymes and, in association with beta-lactamines, offer wide spectrum bactericidal action (Gram negative bacilli, anaerobic germs, methicillin-sensitive staphylococci and streptococci) and can be used as first-line treatment in certain community-acquired and nosocomial infections. SIDE EFFECTS: Widespread use of these inhibitors selects intermediate or resistant strains. Toxicity is low. Undesirable effects (poor digestive tolerance for oral formulations) are dose-dependent. RIGOROUS PRESCRIPTION: Recent development of bacterial resistance emphasizes the importance of rational use of these associations and the need for a better definition of the optimal doses. Prescriptions must avoid underdosing and excessively long treatments. Treatment should be simplified if sensitivity to an antibiotic with a narrower spectrum is recognized.

[HIV infection and "malignant" strongyloidiasis]. / Infection VIH et anguillulose "maligne".

Disseminated Strongyloides stercoralis infection occurs in immunocompromised patients. Despite the epidemiological overlap of HIV infection and strongyloidiasis observed in certain parts of the world, only six cases of dissemination have been reported in AIDS patients. The clinical presentation has no special features, except for the frequency of other opportunistic infections. The prognosis is poor. This lack of association between disseminated strongyloidiasis and HIV infection had led to the exclusion of extra-intestinal forms of this paraistosis from the revised classification of AIDS.

Genetic environment of acquired bla(ACC-1) beta-lactamase gene in Enterobacteriaceae isolates.

We studied the genetic organization of bla(ACC-1) in 14 isolates of Enterobacteriaceae from France, Tunisia, and Germany. In a common ancestor, ISEcp1 was likely involved in the mobilization of this gene from the Hafnia alvei chromosome to a plasmid. Other genetic events involving insertion sequences (particularly IS26), transposons (particularly Tn1696), or sulI-type integrons have occurred, leading to complex genetic environments.

Pharmacokinetics of quinolones with special reference to the respiratory tree.

Successful treatment of respiratory tract infections with the fluoroquinolones requires knowledge about whether the prescribed antibiotic will reach the site of infection at clinically active concentrations. The difficulty in extrapolating pharmacokinetic information from animal models to man has resulted in new approaches to determine the distribution of antibiotic within the human lung. Bronchoalveolar-lavage (BAL) allows the collection of epithelial-lining-fluid, alveolar macrophages, bronchial mucosal samples and sputum, thereby permitting measurement of the cellular and extracellular concentrations of an antibiotic. All fluoroquinolones show similar patterns of penetration into the lung parenchyma, bronchial mucosa or bronchial secretions. The main differences between these agents concern antibacterial potency and the nature, frequency and severity of adverse reactions. Many respiratory infections are caused by obligate or faculative intracellular pathogens, which are likely to be eradicated by the intracellular and extracellular concentrations of quinolones achieved and is supported by models of phagocytic cell function.

[Role of the microbiology laboratory in the diagnosis of nosocomial diarrhea]. / Apport du laboratoire de microbiologie au diagnostic des diarrhées nosocomiales.

Diarrhea that occurs in hospitalized patients is frequent and may be due to infectious or noninfectious causes. In adults with nosocomial diarrhea, the most commonly detected agent is Clostridium difficile; in children, rotaviruses are predominant. Various studies have shown that bacterial enteric pathogens (e.g. Salmonella spp., Shigella spp., Campylobacter spp...) or parasites are common causes of community-acquired diarrhea but rarely cause nosocomial enteritis. Stool cultures for these pathogens and ova and parasite examination should not be performed in patients hospitalized for more than three days unless there are plausible clinical or epidemiological reasons to do so. In contrast, C. difficile toxins assay (and rotavirus screening in children) should be primarily requested. The detection of C. difficile toxin B by stool cytotoxicity assay remains the 'gold standard'. Identification of toxin A (or A + B) can also be performed by immuno-enzymatic (ELISA) tests: results may be obtained in three hours. Electronic microscopy is the standard method for rotavirus diagnosis but tests using latex agglutination or immuno-enzymatic assay are now available. Various typing methods have been developed and may be routinely used in epidemiological investigations.

Identification of a carbenicillin-hydrolyzing beta-lactamase in Alcaligenes denitrificans subsp. xylosoxydans.

Eleven strains of Alcaligenes denitrificans subsp. xylosoxydans produced a beta-lactamase with a pI of 5.7 with kinetic data characteristic of a PSE-1-type enzyme. A CARB-type enzyme was identified by using an intragenic DNA probe of blaCARB. Hybridization of genomic DNA after XbaI restriction and pulsed-field electrophoresis suggested a chromosomal location for the gene.

Opportunistic nosocomial multiply resistant bacterial infections--their treatment and prevention.

One of the most difficult problems confronting the clinician who deals with nosocomial infections is that of microbial resistance. The predominant nosocomial infections (urinary tract infections, pneumonia, septicaemia, surgical wound infections) involve increasing numbers of Gram-positive bacteria, Staphylococcus epidermidis, Corynebacterium jeikeium or resistant enterococci as well as new multiresistant Gram-negative bacilli such as Xanthomonas maltophilia, Acinetobacter baumannii and Alcaligenes xylosoxydans. The emergence and spread of Klebsiella pneumoniae and other Enterobacteriaceae producing novel plasmid-mediated beta-lactamases active against third-generation cephalosporins contribute to the difficulty in treating nosocomial infections.

Bactericidal in-vitro activity of beta-lactams and beta-lactamase inhibitors, alone or associated, against clinical strains of Acinetobacter baumannii: effect of combination with aminoglycosides.

Five Acinetobacter baumannii strains of various phenotypes were selected on the basis of the results of a national survey in France in 1991. beta-Lactamases in Acinetobacter isolates were characterized by isoelectrofocusing. We carried out a 24 h time-kill study to assess the bactericidal effect of antibiotic alone or in combination against A. baumannii strains. The initial inoculum was 10(6) cfu/mL. Antibiotics were tested at MIC x 2 when an antibiotic was tested alone and at the MIC for each combination including ticarcillin, piperacillin, ceftazidime or imipenem with or without amikacin or netilmicin and/or beta-lactamase inhibitors. Concentration of inhibitors were: 2 mg/L for clavulanic acid, 4 mg/L for tazobactam and 8 mg/L for sulbactam. Sulbactam and tazobactam showed an intrinsic in-vitro activity against strains susceptible to ticarcillin. A complete killing at 24 h was observed when beta-lactams were combined with amikacin in comparison with antibiotics alone. Synergy was lost when the strain presented a low resistance level to beta-lactams or aminoglycosides except for ticarcillin. Combinations of sulbactam with ticarcillin showed the best bactericidal activity against strains multiresistant to beta-lactams.

Clinical and bacteriologic epidemiology of extended-spectrum beta-lactamase-producing strains of Klebsiella pneumoniae in a medical intensive care unit.

The epidemiology of extended-spectrum beta-lactamase (ESBL)-producing strains of Klebsiella pneumoniae was studied over a 16-month period in a medical intensive care unit (ICU). A control program involving enhanced isolation procedures, surveillance cultures at admission and then at 1-week intervals, and selective digestive decontamination (SDD) was instituted. Phenotypic and genotypic markers (plasmid content and DNA macrorestriction polymorphism determined by pulsed-field gel electrophoresis) were used to compare 138 strains of ESBL-producing K. pneumoniae. The incidence of colonization and/or infection with ESBL producers was 11.9%. ESBL-producing K. pneumoniae strains were isolated from 64 of 65 patients. Fifty-five cases were considered acquired in the ICU, while nine cases were imported. Forty-five infections occurred in 32 patients; 20 infections involved the urinary tract. SDD failed to reduce the incidence of acquisition of ESBL-producing K. pneumoniae. Combined use of markers was necessary to achieve accurate differentiation of strains. A single epidemic clone (SHV-4 beta-lactamase-producing K. pneumoniae) was the cause of 85% of the ICU-acquired cases. Sporadic occurrence of SHV-5, TEM-3, SHV-2, and SHV-3 producers accounted only for a few cases.