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This work deals with the bacteriological study of an immunodeficient infant, delivered by aseptic cesarean section, and subsequently maintained in a plastic isolator. After a short period of germfree maintenance, several strains of bacteria were fortuitously introduced into the isolator, and became established in the infants' gastrointestinal tract. The qualitative and quantitative evolution of the fecal flora of this "heteroxenic" infant was followed for 170 days. Decontamination of the gastrointestinal tract was accomplished with a mixture of antibiotics, and the conditions of maintenance of sterility under antibiotic treatment were studied.

The MS-2 automate for antibiotic susceptibility testing was experimented under conditions different from those recommended by the manufacturer, namely using antibiotic discs from different firms. Susceptibility of eight Enterobacteriaceae strains recovered from urine to nine antibiotics borne by discs from three different firms was tested. Results obtained with the different brands of discs were dissonant in less than 7% of cases (major and minor disagreements compounded). Major discrepancies ranged from 2.8 to 4.2% according to the origin of discs. The reproducibility study found consistent results in 87.5% of cases, and satisfactory results (i.e. minor discrepancies excluded) in 93.5% of cases.

A performance analysis was established between three methods for testing of bacterial susceptibility to sixteen antibiotics: agar dilution or minimal inhibitory concentration (MIC) method, agar diffusion or DISK method, and semi-automatic dilution in liquid medium or ABACR method. Precision of the three methods was determined using three reference strains in repetition experiments (9 repetitions for MIC, 60 repetitions for both DISK and ABAC). The results show that MIC method was the most precise, and that the precision of DISK and ABAC methods was not sifnificantly different. Fidelity of both DISK and ABAC methods was compared in taking as reference the MIC of 200 wild strains of Gram-negative bacteria. Omitting the data concerning trimethoprim-sulfamethozoaxol, the results were found concordant between DISK and MIC methods in 68.6 percent of the cases, between ABAC and MIC methods in 73.6 percent, and between ABAC and DISK methods in 68.9 percent. With regard to MIC, ABAC method gave results slightly better than those of DISK method, especially for five antibiotics: gentamicin, minocyclin, doxycylin, chloramphenicol and polymyxin B. So, the ABAC method looks very interesting for a semi-automatic routine method in testing bacterial susceptibility to antibiotics.

The gallbladder wall, gallbladder lumen and bile duct intraoperative sampling materials had been examined in 52 patients with an operation on the biliary tract. All patients were treated by only one infusion before operation: 1 g ceftriaxone was given to 26 patients and 2 g ceftriaxone to the 26 others. Bacterial species were isolated on twenty patients. There was no significant difference in infection rate and organism identity between bacterial flora isolated from patients receiving 1 g ceftriaxone and patients receiving 2 g. Isolated germs were enterobacteriaceae (15) streptococci (14) and anaerobic bacteria (8). The mean count of bacteria in bile is 10(4) germs/ml. Half positive sampling materials contains more than one bacterial strain. The bacterial flora isolated from bile has characteristics of mixed flora infection. Ceftriaxone had a good efficacy in antibiotic prophylaxis.