SDS-PAGE for identification of species belonging to the Mycobacterium fortuitum complex.

We performed a study to determine the usefulness of SDS-PAGE of whole cell proteins for the characterization of species of rapidly growing mycobacteria belonging to the Mycobacterium fortuitum complex. Strains included 37 M. fortuitum, 32 M. chelonae, 10 M. peregrinum, 5 M. abscessus, and 3 M. mucogenicum. Eight collection strains (including type strains of the five species) were also included in the study. All strains yielded between 44 and 58 bands in the electrophoretograms. Intraspecies similarity showed Dice coefficients higher than 95%, with only one strain of M. fortuitum having a six-band difference (Dice coefficient 87.75%). However, interspecies similarity was always below 75%, the similarity being higher between M. fortuitum and M. peregrinum (75.51%) and between M. chelonae and M. abscessus (54.9%). Visual examination of the electrophoretograms was sufficient for species characterization. SDS-PAGE of whole cell proteins is a useful technique for identification of isolates of the M. fortuitum complex, and is easy to perform without the need for complex or expensive equipment.

Inoculum standardization for antifungal susceptibility testing of filamentous fungi pathogenic for humans.

Two methods of inoculum preparation for filamentous fungi were compared: counting with a hematocytometer and spectrophotometric adjustment. One hundred eighty-two filamentous fungi pathogenic for humans were used. Colony counts were done for all inoculum preparations. The agreement between the hematocytometer counts and the colony counts (CFU per milliliter) was 97.2%. The reproducibility between the hematocytometer counts and the colony counts by means of an intraclass correlation coefficient was 0.70. Pearson's correlation index for hematocytometer counts versus colony counts was 0.56, whereas that for optical density versus colony counts was 0.008. Both methods can be used for inoculum size adjustment. However, the use of the spectrophotometric method requires that each species be standardized separately.

Effects of single oral doses of gemifloxacin (320 milligrams) versus trovafloxacin (200 milligrams) on fecal flora in healthy volunteers.

Gemifloxacin and trovafloxacin were administered to 12 volunteers in a randomized crossover trial with a 2-week washout period. Stool samples were collected predose and 1, 2, and 3 days postdose. Both quinolones reduced the number of organisms of the family Enterobacteriaceae and aerobic gram-positive organisms. Escherichia coli reduction was greater with gemifloxacin than with trovafloxacin, with postdose isolation of quinolone-resistant strains for which MICs of trovafloxacin were higher than those of gemifloxacin.

Pseudo-outbreak of Aeromonas hydrophila isolates related to endoscopy.

Over a two-month period there was a sudden increase in Aeromonas hydrophila isolated from colon i.e., biopsies from patients without related symptoms. Strains were studied by biotyping (API 20 NE, bioMerieux), antibiotyping, plasmid analysis, SDS-PAGE of whole cell proteins and toxicity for cell cultures. All strains gave identical results. In particular SDS-PAGE of whole cell proteins showed an identical electrophoretic pattern for all the strains, and so all were considered to be of the same clone. During the study period, endoscopic materials were disinfected with quaternary ammonia and glutaraldehyde phenate. After these disinfectants were changed to glutaraldehyde 2%, there were no more isolates of A. hydrophila from the biopsies. We conclude that SDS-PAGE can be a useful technique for epidemiological characterization of A. hydrophila.

Number of days required for recovery of mycobacteria from blood and other samples.

From 1991 to 1996, 541 blood samples were tested for the presence of mycobacteria; 56 were positive (30 patients, 26 human immunodeficiency virus positive). The species found were Mycobacterium avium (41 samples from 18 patients), Mycobacterium tuberculosis (12 samples from 9 patients), and three other species (1 sample each). The average time to detection was 25.23 days (22.65 for M. avium and 35.33 for M. tuberculosis). For 10 patients, the blood isolate was the only mycobacterium detected (4 M. tuberculosis).

[Spontaneous meningitis caused by gram-negative bacilli]. / Meningitis espontánea por bacilos gramnegativos.

OBJECTIVE: To analyze the causative factors, clinical and microbiological characteristics, and prognosis in spontaneous meningitis caused by Gram-negative rods in adult patients. METHODS: Descriptive and retrospective study of all clinical records and microbiological findings in patients diagnosed of meningitis by Gram-negative bacilli, from 1973 to 1995, at Fundación Jiménez Díaz. RESULTS: Twenty patients had spontaneous meningitis caused by Gram-negative bacilli (2.1% of all diagnosed meningitis during this period). Fourteen patients were older than 65 years (range: 36-81; p < 0.05). Ninety-five percent of cases had an extranosocomial origin (p < 0.001). Ninety percent of patients had some underlying disease (p < 0.001). Twelve patients were immunosuppressed. Seven patients had changes in the urinary tract or repeated UTI infections. The most common clinical symptoms were a decrease in consciousness level, fever, and neck stiffness. Cerebrospinal fluid (CSF) in 18 patients showed cellular and biochemical changes. The CSF smear revealed the presence of Gram-negative bacilli in 15 patients. E. coli was the microorganism recovered most frequently. Immunosuppression (p < 0.05), septic shock (p < 0.001) and antimicrobial therapy not including a third generation cephalosporin (p < 0.01) were independently associated with mortality. CONCLUSIONS: Spontaneous meningitis by Gram-negative bacilli is an uncommon infection. It occurs mainly in immunosuppressed patients older than 65 years or with changes in the urinary tract. It usually has an extranosocomial origin. The investigation of CSF is a highly effective for diagnosis. Therapy with third generation cephalosporins has notably improved its prognosis.