[Significant decrease of rate and incidence of methicillin resistant Staphylococcus aureus in a French general hospital between 1999 and 2001]. / Surveillance des bactéries multirésistantes: diminution significative du taux et de l'incidence de Staphylococcus aureus résistant à la méticilline (SARM) dans un centre hospitalier général entre 1999 et 2001.

In our French general hospital of 1000 hospitalization beds, a specific isolation for multiresistant bacteria (MRB) colonized or infected patients was set up since 1998. To assess the impact of these recommendations, the rate and incidence of methicillin resistant Staphylococcus aureus (MRSA), the most important MRB recovered in French hospitals, were calculated for each year since 1999. All the strains isolated from clinical samples, except duplicates (same bacteria in the same patient), were included. The results were compared with the chi(2)-test. Between 1999 and 2001, 644 strains were isolated. MRSA rate went from 46% in 1999 to 41% in 2000, and to 37% in 2001 (P = 0.007). In the study proposed by the CCLIN Paris-Nord, in April, May and June of each year, the rate of SARM was 52% in 1999, 43% in 2000 then 36% in 2001. The incidence per 100 admissions was 0.73 in 1999, 0.59 in 2000 and 0.54 in 2001 (P = 0.002) and the incidence per 1000 hospitalization days was, respectively, 0.92, 0.74, 0.67 in 1999, 2000 and 2001 (P < 0.001). The significant decrease of the rate and incidence of SARM proved that the isolation policy was effective in our hospital. This decrease was obtained through cooperation between staff members, bacteriologists and hospital nosocomial infection committee members. We know that measures to prevent MRSA cross transmission are very difficult to maintain over a long time and we hope that indicators would not increase next year. The use of alcohol based hand-rub since May 2002 should contribute to maintain this decrease.

TEM-24 extended-spectrum beta-lactamase-producing Enterobacter aerogenes: long-term clonal dissemination in French hospitals.

OBJECTIVE: To investigate interstrain relatedness of TEM-24-producing Enterobacter aerogenes clinical strains isolated between 1993 and 1998 in 10 French hospitals from nine areas by pulsed-field gel electrophoresis (PFGE) and plasmid patterns. METHODS: Fifteen TEM-24-producing strains and a set of 16 control strains having various other antibiotic resistance phenotypes were genotyped by PFGE. Plasmid DNA from TEM-24-producing strains and transconjugants was analyzed. RESULTS: Analysis of XbaI macrorestriction patterns revealed only minor variations, and showed that all 15 TEM-24-producing strains were closely related. Some isolates originating from distant areas had indistinguishable patterns. According to their clustering correlation coefficients, they were also genomically distant from the control strains. Two plasmid patterns were observed in TEM-24-producing strains, one of them in 13 of the strains. Large plasmids of 85 kb encoding TEM-24 beta-lactamase were present in all isolates and, in all except one strain, could be transferred with high frequency by conjugation. CONCLUSIONS: These results confirm that the spread of the TEM-24 extended-spectrum beta-lactamase in France was essentially due to the dissemination of a single clone.

Arbitrary primed PCR rules out Clostridium difficile cross-infection among patients in a haematology unit.

Eight out of 20 (40%) patients with haematological malignancies hospitalized in the same unit of our hospital from 24 January to 24 April 1995, suffered from diarrhoea due to Clostridium difficile. The C. difficile isolates were characterized by serotyping and by arbitrary primed polymerase chain reaction (AP-PCR) using three different 10-mer oligonucleotides. It was found by serotyping that five patients had non-typeable isolates and three had serogroup H isolates. The AP-PCR typed all the isolates and yielded various patterns suggesting that there had been no cross-transmission between the patients. Control faecal sample cultures showed that two patients were still carrying the same isolates after specific treatment with vancomycin or metronidazole, and that one patient had acquired an isolate with a new AP-PCR type. AP-PCR was found to be a rapid, effective discriminative method for the immediate epidemiological tracking of hospital-acquired infections due to C difficile.

Pyxigraphic sampling to enumerate methanogens and anaerobes in the right colon of healthy humans.

BACKGROUND: A major limitation in studying the proximal human colonic flora is the lack of suitable sampling methods. The aim of this study was (1) to describe a prototype technique, pyxigraphy, which uses swallowed capsules containing a mechanism allowing the remote control of sampling the gastrointestinal tract contents, and (2) to use this sampling method to examine the distribution of methanogens in the colon of methane (CH4) excretors and non-CH4 excretors. METHODS: In six CH4 excretors and four non-CH4 excretors, samples of the right colonic contents were obtained by means of the pyxigraphic sampling method. Methanogens and total anaerobes were enumerated in both the right colonic and fecal contents. RESULTS: In CH4 excretors, the concentration of methanogens was higher in the feces than in the right colonic contents, representing 12% and 0.003%, respectively, of the total anacrobes (P < 0.02). In non-CH4 excretors, no difference was observed, methanogens representing < 0.003% of the total anaerobes in both the right colonic and fecal contents. CONCLUSIONS: Pyxigraphy is a noninvasive, simple, and safe sampling method that allows to study the microbial populations of the proximal colon. The results obtained showed that methanogens preferentially colonize the distal part of the colon in CH4 excretors.

Interrelations between populations of methanogenic archaea and sulfate-reducing bacteria in the human colon.

In humans, CH4 is produced in the colon by methanogenic archaea and is detected in breath samples from approximately 50% of healthy adults, identified as CH4-excretors. Methanogenesis and sulfate reduction have been described as two mutually exclusive processes, potentially regulated by sulfate availability. To determine whether microbial population balances reflected these apparently co-regulated activities, we compared sulfate-reducing bacteria, methanogenic archaea, sulfate and sulfide concentrations in faeces of 10 CH4-excretors (CH4+) and 9 non-CH4-excretors (CH4-). The mean +/- SE of the logarithm of methanogenic archaea per gram wet weight were 9.0 +/- 0.2 and 4.0 +/- 0.7 for CH4+ and CH4-, respectively (P < 0.001). Sulfate-reducing bacterial counts were 6.5 +/- 0.1 and 7.3 +/- 0.2, respectively (P < 0.001). Fecal sulfate and sulfide concentrations did not differ between groups. These results suggest that a competitive interrelation between methanogenic archaea and sulfate-reducing bacteria occurs in the human colon. However, it does not lead to a complete exclusion of the two populations.

Prevalence of Staphylococcus aureus and coagulase-negative staphylococci with decreased sensitivity to glycopeptides as assessed by determination of MICs.

The prevalence of staphylococci with decreased sensitivity to glycopeptides was assessed at a Paris hospital by determination of the MICs. The values obtained using the MIC method were compared to those obtained using the routine disk agar diffusion method. One hundred independently isolated strains were tested including 57 Staphylococcus aureus isolates and 43 coagulase-negative staphylococci (CNS). For all strains vancomycin MICs were less than or equal to 4 mg/l but for 5.3% of the Staphylococcus aureus isolates and 25.6% of the CNS isolates teicoplanin MICs were high (greater than or equal to 8 mg/l). Moreover, teicoplanin MICs did not correlate well with zone sizes. The MIC method is therefore recommended for evaluating the susceptibility of staphylococci to teicoplanin.