Relevance of routine use of the anaerobic blood culture bottle.

Using the BacT/Alert automated system, we conducted a 1-year retrospective study on blood cultures, focusing on the relevance of routine use of the anaerobic bottle. The rate of patients with positive blood cultures was 19.7%. Among these, 13.5% had a positive anaerobic bottle in the absence of any aerobic bottle, and 2/3 of these grew with nonobligate anaerobes. These patients were hospitalized in 20 out of 26 wards of the hospital group. For 65.4% of the monomicrobial-positive blood cultures growing Enterobacteriaceae, the anaerobic bottle detected growth earlier than the corresponding aerobic bottle. These data suggest that, in our institution, the use of an anaerobic bottle is still relevant.

Colonization and infection of pulmonary artery catheter in cardiac surgery patients: epidemiology and multivariate analysis of risk factors.

OBJECTIVE: To assess the incidence and etiology of colonization and infection of pulmonary artery catheters inserted in cardiac surgery patients. To determine the influence of some variables on the risk of developing pulmonary artery catheter colonization and infection. DESIGN: Prospective observational study of pulmonary artery catheters inserted into the internal jugular vein that were in place for >48 hrs over a 13-month period. Data collected included age, gender, nature of the cardiac surgery intervention, duration of extracorporeal circulation, date of insertion and removal, subsequent infection, and curative antimicrobial therapy. End points were pulmonary artery catheter colonization with >or=10(3) colonies on quantitative cultures and pulmonary artery catheter-related bacteremia. Risk factors for colonization were determined by multiple logistic regression. SETTING: A 17-bed cardiac surgery intensive care unit in a 480-bed teaching hospital in Paris. PATIENTS: Patients undergoing cardiac surgery procedures between May 1, 1997, and May 31, 1998. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Of 164 pulmonary artery catheters inserted in 157 patients, 19 (11.6%) and 1 (0.6%) were associated with colonization (mean duration of catheterization, 7.5 +/- 2.8 days) and bacteremia, respectively. These data represent an incidence of 17.7 and 0.93 episodes per 1000 catheterization-days, respectively. Pulmonary artery catheter colonization was caused by Gram-positive cocci in 48% (67% were coagulase-negative staphylococci), Gram-negative rods in 48%, and Candida albicans in 4%. From multivariate analysis, >4 days of catheterization was the single variable associated with a significantly increased risk of pulmonary artery catheter colonization (odds ratio, 9.81; 95% confidence interval, 1.24-77.5, p = .03). CONCLUSIONS: Our data show that the risk of pulmonary artery catheter-related colonization and bacteremia is quite low despite the use of a high-risk insertion site. In cardiac surgery patient populations, a trial evaluating the impact of a systematic pulmonary artery catheter removal after 4 days is warranted.

Outbreak of methicillin-resistant Staphylococcus aureus with reduced susceptibility to glycopeptides in a Parisian hospital.

Epidemiological relationships were investigated between 40 methicillin-resistant Staphylococcus aureus (MRSA) strains with decreased glycopeptide susceptibility isolated from November 1998 to March 1999 from 39 patients (17 infected and 22 colonized patients) in nine wards of the Broussais Hospital, Paris, France. Reduced glycopeptide susceptibility was readily detected on brain heart infusion (BHI) agar containing 6 microg of teicoplanin per ml and on gradient plates, but not by the standard disk diffusion method. The MICs of vancomycin and teicoplanin, determined on BHI agar, were 4 and 8 to 32 microg/ml, respectively (standard antibiotic dilution), and 4 to 8 and 8 to 32 microg/ml, respectively (E-test). All strains were resistant to macrolides, aminoglycosides, tetracycline, rifampin, sulfonamides, and pefloxacin, showed reduced susceptibility to fusidic acid and fosfomycin, and were susceptible to trimethoprim and chloramphenicol. Pulsed-field gel electrophoresis and lysotyping revealed that a multidrug-resistant MRSA clone with decreased susceptibility to glycopeptides has been discretely endemic since at least 1996 in our institution, where it was responsible for an outbreak in November and December 1998.

Methicillin-resistant Staphylococcus aureus. Nosocomial acquisition and carrier state in a wound care center.

OBJECTIVE: To assess methicillin-resistant Staphylococcus aureus (MRSA) nosocomial acquisition and carrier state in a wound care center. DESIGN AND SETTING: The results of an intervention to control MRSA were compared with those of historical controls at the wound care center of university-based Hôpital Broussais, Paris, France. PATIENTS: Patients admitted for specific care of chronic ulcers and surgical wounds. MAIN OUTCOME MEASURES: Incidence rates of MRSA carriers and acquisition in wounds. RESULTS: Of 88 patients admitted during a 3-month preintervention period in 1993, 18 (21%) were MRSA carriers. Of 334 patients admitted in 1994 and 395 in 1996, 65 (19.5%) and 81 (20.5%) were MRSA carriers, respectively (P=.80). In 1993, 6 (9%) of 70 patients without MRSA acquired MRSA wound infections; the corresponding numbers were 6 (2.2%) of 269 in 1994 and 3 (0.9%) of 314 in 1996. Despite that the number of MRSA carriers remained stable at admission to the wound care center, the rate of MRSA infections in wounds per 100 noncarriers decreased significantly between the preintervention period and subsequent years: 1994 (P=.02) and 1996 (P=.002). CONCLUSIONS: Although our results are limited by the use of historical controls, they showed that simple infection control measures, such as the use of soap and water and barrier precautions associated with staff education, seemed to significantly reduce MRSA infection rates in patients with chronic skin breaks.

[Stenotrophomonas maltophilia endocarditis following mitral valve prosthesis implantation. Report of a case]. / Endocardite à Stenotrophomonas maltophilia après plastie mitrale. A propos d'un cas.

The authors report the first case of early postoperative endocarditis after mitral valvuloplasty due to Stenotrophomonas Maltophilia, a Gram negative organism, in a 37 year old man with no special risk factors. Pyrexia and mitral valve vegetations were the main features, and, in the absence of complications or of embolism, the patient was treated initially with triple antibiotherapy (ceftazidime, amikacine, ciprofloxacine). Relapse two weeks after withdrawal of treatment due to two variants of Stenotrophomas Maltophilia, one of which was resistant to ciprofloxacine, and the presence of a large vegetation, required repeat mitral valvuloplasty and a change in antibiotic therapy (ticarcilline with clavulanic acid, trimethoprim sulphamethoxazole, colistine). This time, the outcome was good. The little known Stenotrophomonas Maltophilia infectious endocarditis is a serious complication and, in the absence of standardised management, the authors suggest that, in view of the multi-resistant character of the organism and in the light of this case, surgery should be considered in association with prolonged antibiotic therapy.

Colonization by Acinetobacter baumanii in intensive-care-unit patients.

We prospectively studied the value of systematic rectal swabs performed for the detection of colonization and the prediction of infections by Acinetobacter baumanii in 751 consecutive patients admitted to five intensive-care units (ICUs) over an 8-month period. Gastrointestinal tract colonization was found in 8.7% of ICU admissions. The positive and negative predictive values of rectal swabs for the detection of subsequent infection were 17% and 99%, respectively. Sensitivity and specificity were 55% and 93%, respectively. We also determined the comparative values of rectal or nasal swabs and skin cultures for the detection of A baumanii colonization in 25 patients already colonized or infected with A baumanii. The combination of rectal and nasal swabs was positive in 20 (80%) of 25. The results of the present study suggest that detection of gastrointestinal tract A baumanii colonization is not an accurate predictor of subsequent A baumanii infection and that combined rectal and nasal swabs might be used for the detection of A baumanii colonization in ICU patients.

Carbapenem resistance in a clinical isolate of Citrobacter freundii.

Carbapenem resistance was studied in two sets of Citrobacter freundii strains: (i) strain CFr950, resistant to imipenem (MIC, 16 microg/ml) and isolated in vivo during imipenem therapy, and strain CFr950-Rev, the spontaneous, imipenem-susceptible revertant of CFr950 selected in vitro, and (ii) strains CFr801 and CFr802, two imipenem-resistant mutants selected in vitro from the susceptible clinical isolate CFr800. In all strains, whether they were imipenem-susceptible or -resistant strains, production of the cephalosporinase was derepressed and their Km values for cephaloridine were in the range of 128 to 199 microM. No carbapenemase activity was detected in vitro. The role of cephalosporinase overproduction in the resistance was demonstrated after introduction of the ampD gene which decreased the level of production of cephalosporinase at least 250-fold and resulted in an 8- to 64-fold decrease in the MICs of the carbapenems. The role of reduced permeability in the resistance was suggested by the absence, in CFr950 and CFr802, of two outer membrane proteins (the 42- and 40-kDa putative porins whose levels were considerably decreased in CFr801) and the reappearance of the 42-kDa protein in imipenem-susceptible strain CFr950-Rev. This role was confirmed after introduction of the ompF gene of Escherichia coli into the CFr strains, which resulted in 8- to 16-fold decreases in the MICs of carbapenems for CFr802 and CFr950. We infer from these results that the association of reduced, porin-mediated permeability with high-level cephalosporinase production, observed previously in other gram-negative bacteria, may also confer carbapenem resistance on C. freundii.

Inducible and constitutive expression of resistance to glycopeptides and vancomycin dependence in glycopeptide-resistant Enterococcus avium.

A clinical isolate of Enterococcus avium, Ea1, which exhibited inducible, low-level resistance to vancomycin and teicoplanin, and two mutants selected from this strain, Ea3 and Ea31, were studied. Ea3 was vancomycin dependent and derived from Ea1, while Ea31 was not vancomycin dependent, was constitutively resistant, and was derived from Ea3. Hybridization studies revealed that vanA was present in Ea1 and suggested that it was located on a high-molecular-weight plasmid. In the absence of induction, Ea1 synthesized only the natural UDP-MurNAc-pentapeptide precursor, and after induction it synthesized an additional precursor identified as UDP-MurNAc-tetrapeptide-D-lactate. The latter was the only precursor found in Ea3 and Ea31, even after precursor accumulation. From these results, we infer that (i) the low level of resistance to glycopeptides in strain Ea1 may be in part due to the residual synthesis of the normal precursor and (ii) the vancomycin dependence of mutant Ea3 could be due to the fact that this strain does not produce any peptidoglycan precursor in the absence of induction.

Revisited indications for bone marrow examinations in HIV-infected patients.

We reviewed the indications for and the results of bone marrow examination (BME) from HIV-infected patients as an attempt to improve its diagnostic yield. One-hundred-and-eight bone marrow specimens from 90 patients during a 3-year period were examined. A cytological, histological and microbiological study was carried out on the specimens. Forty-three evaluable examinations (40% of total) performed for cytopenia showed normo- or hypercellularity in 33 (77%). Fifty bone marrow specimens were cultured for mycobacteria with a yield of 42% when the indication was persistent fever. Positive cultures yielded Mycobacterium avium complex in 8 out of 12 patients. Twenty-seven patients had both culture and biopsy; granulomas were associated with all the positive (10/10) and with 1 out of 17 negative cultures (chi-square test: p < 0.001). A bone marrow involvement with lymphoma was found in 2 out of 6 patients with previously diagnosed lymphoma, and biopsy revealed a lymphoma in 2 patients. Morphological bone marrow examination should be associated with other techniques in order to appreciate bone marrow production. Bone marrow biopsy is useful for the investigation of persistent fever since granulomas suggestive of disseminated mycobacteria are frequent and allow a treatment to be initiated before microbiological confirmation and antibiotic susceptibility test.

Analysis of pristinamycin-resistant Staphylococcus epidermidis isolates responsible for an outbreak in a Parisian hospital.

In 1990, over a 6-month period, an increase from 1 to 10% in the incidence of pristinamycin resistance among coagulase-negative staphylococci was observed in four intensive care units of a Parisian hospital. Twenty-three such isolates, as well as 25 pristinamycin-susceptible Staphylococcus epidermidis isolates, were collected and typed by analyzing various bacterial constituents. Two structurally related plasmids of 7.3 and 14.3 kb, carrying the gene vga encoding resistance to pristinamycin, were detected in the 23 pristinamycin-resistant coagulase-negative staphylococci which were identified as S. epidermidis. Although related by numerous common characteristics, 20 of these 23 isolates could be divided into two types, A (17 isolates) and B (three isolates). These types were characterized on the basis of their plasmid contents and hybridization patterns obtained when the EcoRI-digested DNA was probed with plasmid pIP1551 containing an internal fragment of the insertion sequence IS256. These findings suggest that the dissemination of type A epidemic strains was, in large part, responsible for the outbreak.

Antimicrobial resistance in Streptococcus pneumoniae: an epidemiological survey in France, 1970-1990.

The antimicrobial resistance of Streptococcus pneumoniae was surveyed in 1970-1990 at Saint Joseph and Broussais hospitals in Paris (3,279 isolates) and in 1984-1990 at the National Reference Center for Pneumococci (NRCP) in Créteil (8,128 isolates). All isolates were tested for susceptibility and serotyped. At St. Joseph and Broussais hospitals, the rate of resistance to tetracycline increased from 14% in 1970 to 46.5% in 1978 and then decreased to approximately 20% in 1988-1990. Resistance to chloramphenicol appeared in 1972; its frequency remained at less than 10% until 1990. Resistance to macrolides was first detected in 1976, increased to 20% in 1984, and reached 29% in 1990. Among strains submitted to the NRCP, resistance to penicillin (MIC, greater than or equal to 0.1 mg/L) remained infrequent (less than or equal to 1.1%) between 1984 and 1986 but then increased steadily, reaching 12% in 1990. The frequency of high-level resistance to penicillin (MIC, greater than 1 mg/L) among penicillin-resistant pneumococci increased from 13% in 1988 to 48% in 1990. Compared with other serotypes, the penicillin-resistant serotype isolated most frequently (23F, 49.3%) was more often highly resistant to penicillin and was more often multiresistant.