Colonization of the digestive tract has been supposed to be the source of many hospital-acquired infections, especially nosocomial pneumonia. To assess the relationship between oropharyngeal and gastric colonization and subsequent occurrence of nosocomial pneumonia, we prospectively studied 86 ventilated, intensive care unit (ICU) patients. Oropharyngeal or gastric colonizations were detected and quantified on admission and twice weekly during ICU stay. When nosocomial pneumonia was suspected on clinical grounds (new chest X-ray infiltrate and purulent tracheal secretions), diagnosis was assessed on fiberoptic bronchoscopy with quantitative cultures of a protected specimen brush sampling and/or a plugged telescoping catheter sampling yielding > or = 10(3) cfu/ml of at least one microorganism. Bacterial strains responsible for colonization and infection (Acinetobacter baumannii, Pseudomonas aeruginosa, Enterobacteriaceae, and Staphylococcus aureus) were compared using pulsed-field electrophoresis. A total of 31 cases (36%) of pneumonia were diagnosed. Oropharyngeal colonization, detected either on admission or from subsequent samples, was a predominant factor of nosocomial pneumonia as compared with gastric colonization. For instance, oropharyngeal colonization with A. baumannii yielded a 7.45-fold estimated increased risk of pneumonia as compared with patients not yet or not identically colonized (p = 0.0004). DNA genomic analysis demonstrated that an identical strain was isolated from oropharyngeal or gastric samples and bronchial samples in all but three cases of pneumonia, due to S. aureus. These findings provide better knowledge of the pathophysiology of nosocomial pneumonia in mechanically ventilated patients.

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Three cases of cutaneous bacillary angiomatosis in HIV-infected patients are reported. They differed profoundly with respect to the extent of the lesions and the clinical course. In two cases, Rochalimaea quintana was identified by direct sequencing of the DNA amplified with the polymerase chain reaction (PCR), whereas an easy, rapid method based on the restriction length of polymorphism analysis of PCR products (PCR-RFLP) was used in the third case. This report illustrates the variations in clinical presentations and evolutive profiles in patients with bacillary angiomatosis, and confirms the causal role of R. quintana in this disease.

A resistant (R) clinical isolate of Alcaligenes denitrificans subsp. xylosoxydans was recovered from CSF during treatment including piperacillin. This variant selected in vivo, and a second variant obtained in vitro from the initially susceptible (S) strain, both exhibited resistance to penicillins (ticarcillin, piperacillin) and cephalosporins, but remained susceptible to latamoxef and imipenem. Clavulanate (2 mg/L) restored the susceptibility of the two R-variants to penicillins. A beta-lactamase of pI 9.5 was detected in both S and R strains, but overproduction was observed only in the in-vivo and in-vitro R-variants. This inducible beta-lactamase hydrolysed benzylpenicillin, cephalothin and cephaloridine efficiently, but amoxycillin, ticarcillin and cefoperazone were only moderate substrates. The enzyme was inhibited by clavulanate, cloxacillin and imipenem (IC50 between 3 and 9 mM), but not by aztreonam and chloride ions (1 mM). Resistance to beta-lactams was not transferable by conjugation to Escherichia coli or Pseudomonas aeruginosa, and DNA agarose gel electrophoresis indicated that no plasmid was present in the isolates. Restriction patterns of chromosomal DNA isolated from the S and R isolates were similar after digestion by NotI and HindIII.