In vitro effects of lidocaine on anaerobic respiratory pathogens and strains of Hemophilus influenzae.

Lidocaine is commonly employed as a topical anesthetic agent during fiberoptic bronchoscopic procedures or transbronchial brushing. Previous studies have demonstrated an inhibitory effect of lidocaine on the growth in culture media of gram-positive and gram-negative organisms, as well as several species of Mycobacterium and various fungi. The current in vitro investigation demonstrates an inhibitory, as well as a bactericidal, effect of lidocaine hydrochloride (in concentrations identical to those encountered during fiberoptic bronchoscopic procedures) on the common anaerobic respiratory pathogens and on multiple strains of Hemophilus influenzae. The finding helps to explaint the difficulty in producing proof via culture of the specific etiologic agent in inflammatory lesions from specimens obtained by fiberoptic bronchoscopic procedures or transbronchial brushing.

Microwave oven irradiation as a method for bacterial decontamination in a clinical microbiology laboratory.

Exposure of 10 frequently isolated clinical pathogens to microwave irradiation resulted in total sterilization with 60 s. Time exposure experiments done with commercially prepared test strips containing Bacillus stearothermophilus spores indicated that 5-min exposure was adequate to insure sterility of small, contaminated loads.

Comparison of the automicrobic system with API, enterotube, micro-ID, micro-media systems, and conventional methods for identification of Enterobacteriaceae.

Identification of Enterobacteriaceae by the AutoMicrobic System Enterobacteriaceae Biochemical Card was evaluated. Recent clinical isolates of enteric gram-negative bacilli (192) and glucose nonfermenters (3) were identified by the AutoMicrobic System, Micro-Media Systems, Micro-ID, API, and Enterotube II in comparison with conventional methods. The AutoMicrobic System and Micro-Media Systems correctly identified 97% of the organisms tested. Micro-ID, API, and Enterotube II correctly identified 94, 92, and 84% of the organisms, respectively. In addition to a high degree of identification accuracy, the AutoMicrobic System was convenient to operate and produced identification results in 8 h. Operation of the AutoMicrobic System also required minimal personnel time because it automatically monitored and interpreted the biochemical reactions and reported organism identifications. The AutoMicrobic System appears to be an efficient and accurate system for the identification of Enterobacteriaceae.

Comparison of three automated systems for antimicrobial susceptibility testing of gram-negative bacilli.

Several instruments for automated or semiautomated susceptibility testing are currently available. Three of these instruments, Autobac (General Diagnostics, Warner-Lambert Co., Morris Plains, N.J.), MS-2 (Abbott Laboratories, Dallas, Tex.), and AutoMicrobic system (AMS) (Vitek, Inc., Hazelwood, Mo.) were compared for antimicrobial susceptibility testing of gram-negative bacilli. A total of 207 isolates representing 29 species of gram-negative bacilli were tested simultaneously by each instrument and by a standardized disk diffusion reference method. Nine antimicrobial agents, including ampicillin, carbenicillin, cephalothin, gentamicin, tobramycin, amikacin, tetracycline, trimethoprim-sulfamethoxazole, and nitrofurantoin were tested. Discrepancies between the results of the automated and reference disk diffusion methods were resolved by agar dilution testing. Overall, 93% of the Autobac and MS-2 results and 83% of the AMS results were in agreement with the results obtained by the reference methods. The results of the Autobac, MS-2, and AMS systems respectively included 3.3, 2.3, and 4.2% major and very major discrepancies. Excessive testing discrepancies were found for certain drugs, including ampicillin, tetracycline, and nitrofurantoin, and for certain organisms, including species of Providencia, Serratia, and Citrobacter. The results of this comparison of three automated systems for antimicrobial susceptibility testing indicate that the Autobac and MS-2 instruments provided highly reliable results. The AMS need further development of its susceptibility testing capability to eliminate an unacceptably high number of minor discrepancies.

Comparison of the Cathra Repliscan II, the AutoMicrobic system Gram-Negative General Susceptibility-Plus Card, and the Micro-Media System Fox Panel for dilution susceptibility testing of gram-negative bacilli.

A comparative evaluation was done to test the accuracy of the Cathra Repliscan II agar dilution system (Diagnostic Equipment, Inc., St. Paul, Minn.), the AutoMicrobic system with Gram-Negative General Susceptibility-Plus Card (Vitek Systems, Inc., Hazelwood, Mo.), and the Micro-Media Fox Panel micro broth dilution system (Micro-Media Systems, Inc., San Jose, Calif.) in determining MICs of 12 antibiotics for 200 gram-negative bacilli. Of the 200 strains tested, 12 isolates did not grow in one of the three systems. The 188 remaining organisms included 158 members of the family Enterobacteriaceae, 20 Pseudomonas spp., 5 Acinetobacter sp., 3 Aeromonas spp., and 2 Vibrio spp. A total of 2,256 organism-antibiotic combinations were analyzed for each system. An MIC was considered correct if two of the three systems were in agreement. When disagreements occurred, correct MICs were determined by the standard agar dilution method. With this criterion, overall agreements of the Cathra Repliscan II system, AutoMicrobic system, and Micro-Media Fox Panel system were 94.7, 94.9, and 95.5%, respectively. Tetracycline (20%), nitrofurantoin (20%), and ampicillin (16%) accounted for 56% of the discrepancies observed. These results indicate that all three systems perform with a high degree of accuracy for susceptibility testing of gram-negative bacilli.

Relation of Campylobacter pyloridis to gastritis and peptic ulcer.

Biopsy specimens from the gastric antral mucosa of 50 patients with upper gastrointestinal complaints were studied by light and electron microscopy and culture. Of 46 assessable specimens, seven were histologically normal, and 39 showed evidence of gastritis. Twenty-seven of the specimens with evidence of gastritis (69%) contained spiral bacteria, whereas only one of the normal specimens (14%) contained these bacteria (P = .02). Of 17 patients found to have gastric ulcers, 10 (59% [P greater than .10] ) also had spiral bacteria. The bacteria could be seen scattered over the surface of the epithelial cells and just under the layer of mucus but were rarely found inside the epithelial cells. Curved or spiral gramnegative bacilli were isolated from 10 of the specimens on chocolate agar incubated at 37 C under microaerophilic conditions. The bacteria resembled the organism recently named Campylobacter pyloridis by other investigators.