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L R McCarthy

Publications and source records attributed to L R McCarthy.

33 records · Page 2Linked to original sources
PubMed1980

Clinical laboratory evaluation of the Abbott MS-2 automated antimicrobial susceptibility testing system: report of a collaborative study.

The MS-2 system (Abbott Diagnostics, Division of Abbott Laboratories, Dallas, Tex.) was evaluated for its efficacy in determining the susceptibilities of both clinical and selected challenge (nonfastidious, facultative, and aerobic) isolates. The MS-2 results were compared with standard Kirby-Bauer disk diffusion and microdilution results by using fresh clinical isolates. For gram-positive isolates other than enterococci, overall agreement between MS-2 and reference results was 93 to 98%. With enterococci, MS-2 agreement with disk diffusion was 68% but with microdilution was 86% (agreement between disk diffusion and microdilution was 73%). The main discrepancies with enterococci were with cephalothin, penicillin, gentamicin, and kanamycin. With clinical gram-negative isolates, the overall agreement was 91 to 93%, with most discrepancies occurring with Enterobacter spp. and beta-lactam antibiotics (MS-2 versus disk diffusion, 84%; MS-2 versus microdilution, 84%; disk diffusion versus microdilution, 87%) and with Serratia spp. and colistin (false-susceptible results). The agreement of MS-2 results with established reference antibiograms of a special collection of challenge strains was 91 to 97% for the gram-positive cocci and 86 to 98% for the gram-negative strains. (With Enterobacter spp., agreement was 86%, but was greater than 90% for all other organism groups.) Of the 98 finite MS-2 minimum inhibitory concentrations (MICs) that could be directly compared with microdilution MICs, 77 (79%) were within +/- 1 well of the geometric mean microdilution MIC. MS-2 analysis time ranged from 2.8 to 6.5 h (mean, 4.2 h). On the basis of these results, we conclude that the MS-2 can be expected to yield rapid and accurate results with most nonfastidious, facultative, and aerobic pathogens.

Anti-Bacterial Agents↗
PubMed1980

Evaluation of the MS-2 system for rapid identification of Enterobacteriaceae.

The precision, accuracy, and other performance characteristics of the MS-2 (Abbott Laboratories, Diagnostic Division, Dallas, Tex.) system for the identification of Enterobacteriaceae were evaluated in a collaborative study involving three clinical laboratories. When identifying 150 unknown, coded organisms, the MS-2 system was 97%, 98%, and 93% accurate, respectively, in three laboratories. The system showed an overall accuracy of 94% when compared with conventional manual tube methods in identifying 1,154 clinical isolates of 26 species of Enterobacteriaceae. Discrepancies between automated and conventional methods were chiefly caused by biochemical variants, especially among Enterobacter species. The MS-2 system was rapid and simple to operate and produced printed results of bacterial identification in 5 h. The cost of disposable components compared favorably with commercial, visually read systems for identifying Enterobacteriaceae.

Bacteriological Techniques↗
PubMed1979

In vitro activity of sodium fusidate against anaerobic bacteria.

The microtiter broth dilution method was employed to determine the in vitro susceptibility of 525 recent clinical isolates of anaerobic bacteria to sodium fusidate. The minimal inhibitory concentrations of sodium fusidate ranged from </=0.06 to 1.0 mug/ml for 155 strains of anaerobic gram-positive rods and 130 strains of anaerobic gram-positive cocci. Minimal inhibitory concentrations ranging from </=0.06 to 32 mug/ml were observed for 240 strains of anaerobic gram-negative rods. Among the latter group a minimal inhibitory concentration of 16 mug/ml or greater was encountered with 16% of 45 Bacteroides fragilis strains, 19% of 32 Bacteroides thetaiotaomicron, and all 7 strains of Fusobacterium necrophorum. Minimal inhibitory concentrations for Veillonella parvula, the only gram-negative coccus tested, ranged from 0.5 to 8.0 mug/ml.

Bacteria↗
PubMed1979

Antibiotic susceptibility of Haemophilus vaginalis (Corynebacterium vaginale) to 21 antibiotics.

A total of 56 strains of Haemophilus vaginalis were tested for their in vitro susceptibility to 21 antimicrobial agents by an agar dilution method. All strains were inhibited by 1 mug or less of penicillin, ampicillin, carbenicillin, and vancomycin per ml. The cephalosporins were less active; 4 mug of cefazolin per ml, 16 mug of cephalothin per ml, or 128 mug of cephalexin per ml was required to inhibit all strains. Kanamycin, gentamicin, tobramycin, and neomycin were relatively inactive against H. vaginalis. All strains were inhibited by 4 mug of streptomycin per ml and 2 mug of chloramphenicol per ml. Only 57% of the strains were inhibited by 4 mug of tetracycline per ml, whereas 43% were inhibited by 16 to 64 mug/ml. The combination sulfamethoxazole/trimethoprim was relatively inactive against H. vaginalis. All strains tested exhibited minimal inhibitory concentrations of >/=128 mug when tested against colistin, nalidixic acid, and sulfadiazine. Erythromycin and clindamycin were the most active of the antibiotics tested; for all strains the minimal inhibitory concentrations were </=0.06 mug/ml.

Anti-Bacterial Agents↗
PubMed1979

Modified coagglutination procedure for the serological grouping of streptococci.

Cowan I staphylococci coated with antisera to streptococcal groups A, B, C, D, F, and G were used as coagglutination reagents in a modified coagglutination procedure (MCAP). Streptococcal group antigens were extracted with a Streptomyces albus-lysozyme enzyme mixture for 30 min at 55 degrees C and centrifuged, and the supernatant was tested by slide coagglutination. Positive coagglutination reactions occurred within 30 s. The cell pellets from overnight broth cultures and colonies taken directly from sheep blood agar plates were tested and compared with the results of the Lancefield capillary precipitin method. Of the 102 strains of broth-grown cells tested, 100 were grouped by the MCAP and the Lancefield capillary precipitin method. The remaining two isolates were serologically identified only by the MCAP. Of the original 102 strains, 97 were tested by MCAP after extraction of five well-isolated colonies from a sheep blood agar plate. When this latter method was used, 95.9% of the strains were correctly identified. Nonspecific reactions were observed only while testing the MCAP with the direct plate assay. These cross-reactions were remedied promptly by either absorption or dilution of the antisera involved. The MCAP was found to be a rapid and reliable technique for the serological grouping of streptococci.

Agglutination Tests↗
PubMed1978

Comparison of a commercial identification kit and conventional biochemical tests used for the identification of enteric gram-negative rods.

A comparison between 11 Minitek biochemical tests and corresponding conventional tubed media was undertaken with 1,089 isolates of enteric gram-negative rods. Overall correlation between Minitek and conventional biochemicals was 97.4%. Minitek proved to be a time- and space-saving miniaturized biochemical system that can be used effectively for the identification of enteric gram-negative rods.

Bacteriological Techniques↗
PubMed1977

Thymidine-dependent strain of Salmonella oslo selected by trimethoprim-sulfamethoxazole therapy.

A case report describing the isolation of a multiple-drug-resistant strain of Salmonella oslo from urine and stool specimens is presented. After ten days of trimethoprim-sulfamethoxazole therapy, a second strain of Salmonella oslo was isolated from another stool specimen. The second strain was determined to be a thymidine-requiring organism. The significance of this thymidine-requiring strain is described.

Adult↗
PubMed1977

Antimicrobial susceptibility of Haemophilus parainfluenzae.

Fifty random clinical isolates of Haemophilus parainfluenzae were tested for their susceptibility to 10 antibiotics by a microtiter broth dilution method. Three of the strains tested were resistant to ampicillin, whereas eight were resistant to tetracycline. All strains tested were susceptible to chloramphenicol, kanamycin, gentamicin, cephalothin, and colistin. The ranges of minimal inhibitory concentrations for the three remaining antibiotics were: 0.5 to >/=128 mug of penicillin G per ml, 0.03 to 4 mug of carbenicillin per ml, and 1 to 16 mug of erythromycin per ml. Elevated minimal inhibitory concentrations for penicillin and carbenicillin were noted for the three ampicillin-resistant strains. Tests for beta-lactamase production demonstrated the presence of this enzyme in each of the three ampicillin-resistant strains.

Ampicillin↗
PubMed1977

Further modifications of the auxanographic method for identification of yeasts.

A modified auxanographic carbohydrate assimilation procedure for the identification of medically important yeasts is described. This method employs a heavy inoculum of unstarved yeasts, autoclaved yeast assimilation medium, pour plates of shallow depth, and commercially available carbohydrate-impregnated disks. The accuracy of this procedure was established in a comparison with the Wickerham broth method.

Carbohydrate Metabolism↗
PubMed1976

Critical analysis of hypertonic medium and agitation in detection of bacteremia.

Over 18,000 clinical specimens collected in Vacutainer tubes with sodium polyanethol sulfonate were inoculated into modified Columbia broth (MCB) with and without 10% sucrose. The effects of venting and shaking on recovery were studied. The volume of the blood had a definite effect on the recovery rate. When inoculum size was held constant, recovery of aerobic and facultative organisms was maximal in vented and shaken bottles; the presence of sucrose had no demonstrable effect, recovery of anaerobes was maximal using an unvented bottle incubated under stationary conditions; a significantly greater recovery of facultatives and a marginally greater recovery of anaerobes was obtained with the hypertonic formulation. We conclude that a hypertonic formulation of MCB offers no advantage in the recovery of anaerobes but is of value in the recovery of facultatives and anaerobes. It is recommended that blood cultures be routinely inoculated into isotonic MCB and then vented and shaken for at least 4 hours, and hypertonic MCB incubated without venting or shaking.

Aerobiosis↗
PubMed1975

Recurrent Aeromonas sepsis in a patient with leukemia.

A case of recurrent sepsis due to Aeromonas hydrophila in a patient with acute myelogenous leukemia is reported. The patient's first infection leading to bacteremia followed contamination of a mosquito bite by stagnant water. After recovery from the first bacteremia, the patient again became septic with a second strain of Aeromonas hydrophila, which again responded to antimicrobial therapy. It is hypothesized that contamination of the local water supply may have led to the establishment of a gastrointestinal carrier state that produced the second bout of Aeromonas sepsis when the patient was markedly leukopenic. The importance of the oxidase test to differentiate Aeromonas species from members of the family Enterobacteriaceae is re-emphasized.

Adult↗