Automated microdilution MIC results, obtained with the Autoreader (Sensititre, Inc., Salem, N.H.) following 5 h of incubation, were compared with manually read, concurrent control MICs following 18 h of incubation in a three-laboratory comparative study. A total of 704 members of the family Enterobacteriaceae or similar gram-negative organisms were tested against 17 antimicrobial agents. Autoreader MICs were within 1 doubling dilution of control values in 92.9% of instances. Discrepancies of +/- 2 doubling dilutions and +/- 3 or greater doubling dilutions were noted in 4.5 and 2.6%, respectively, of the 7,687 drug-organism combinations analyzed. The majority of errors occurred when beta-lactam antimicrobial agents were tested with a variety of different species. MICs at 5 h, when Pseudomonas aeruginosa was used, were possible in only half the isolates tested and yielded data on only a limited number of drugs in the remaining instances. Excluding results obtained with penicillin and ampicillin, which were uniformly poor, Staphylococcus aureus Autoreader values were within +/- 1 doubling dilution of control values in 93.6% of instances, 5.4% varied by +/- 2 dilutions, and only 1% of test values by +/- 3 or more dilutions from control values for 82 isolates tested against nine antimicrobial agents. Of eight additional S. aureus isolates tested that were resistant to methicillin, only one was read correctly by the Autoreader, with results on the remaining seven appearing as either insufficient growth or as total resistance to all drugs tested. Interlaboratory reproducibility was excellent for selected isolates of S. aureus and gram-negative bacilli. The accuracy of the Sensititre Autoreader MIC results was comparable to that of other same-day quantitative systems for members of the family Enterobacteriaceae and S. aureus, while the economic and procedural advantages of the broth microdilution method was maintained.

Anti-Bacterial Agents↗

PubMed1988

Evaluation of a commercial latex test for Clostridium difficile for reactivity with C. difficile and cross-reactions with other bacteria.

Seventy-eight species of bacteria (739 isolates) were tested for reactivity with a commercial latex test for Clostridium difficile. All noncytotoxic as well as cytotoxic strains of C. difficile reacted positively. Immuno-specific cross-reactions were found only with C. sporogenes, proteolytic C. botulinum, and Peptostreptococcus anaerobius.

Bacterial Toxins↗

PubMed1988

Studies on antifungal agents. 17. Effects of the C-5-substitution on the in vitro activity of novel 3,5-substituted isoxazolidines.

A number of novel 5-(substituted thiomethyl)-3-phenyl-3-(1H-imidazol-1-ylmethyl)-2- methylisoxazolidine derivatives were prepared and evaluated in vitro for antifungal activity in solid agar cultures against Trichophyton rubrum, Aspergillus fumigatus and Candida albicans. The effect of the 5-(substituted thiomethyl) group on the degree and scope of activity was studied and compared to that of the corresponding 5-phenoxymethyl and 5-[(substituted phenyl)thio(or amino)methyl] derivatives.

Antifungal Agents↗

PubMed1988

Studies on antifungal agents. 18. In vitro activity of 5,5-disubstituted-3-phenyl-3-(1H-imidazol-1-ylmethyl)-2-methy lisoxazol idines and related compounds.

The in vitro antifungal activity of a series of novel 5,5-disubstituted-3-phenyl-3-(1H-imidazol-1-ylmethyl)-2-methyli soxazolidines and related compounds against Trichophyton rubrum, Aspergillus fumigatus and Candida albicans was studied. The screening was performed in solid agar cultures and some structure-activity relationships involving the C-5-substitution pattern are discussed.

Aged↗

PubMed1988

Rotavirus and Cryptosporidium shedding in dairy calf feces and its relationship to colostrum immune transfer.

Twenty Holstein calves received 2 L of colostrum twice within 12 h after birth; the first feeding occurred within 2 h of parturition. The increase in adsorption efficiency was related to the gamma globulin provided in the first colostrum feeding. Absorption efficiency ranged from 2.4 to 46.1%. The number of sheddings of rotavirus and Cryptosporidium by the calves during their first 4 wk of life was associated with serum gamma globulin concentration 24 h after birth and absorption efficiency. Absorption efficiency and body weight combined accounted for 60.4% of the variation in the number of sheddings; heavier calves shed more than lighter calves. During the first 4 wk, calves that shed more frequently gained less weight; weight gain was also associated with serum gamma globulin levels 24 h after birth. Colostrum composition varied between quarters of the same cow. Total protein and gamma globulin content of colostrum from the rear quarters was higher than from the front quarters. The association between number of sheddings and absorption efficiency suggest that calves should not be fed colostrum containing less than 9 g/100 ml of total protein.

Animals↗

PubMed1987

Development and evaluation of diagnostic radiometric assays for serogroup 4 L. pneumophila urinary antigens.

We previously reported that 80% of patients with serogroup 1 Legionella pneumophila pneumonia excrete detectable quantities of specific antigens in their urine. The purpose of this study was to determine whether specific antigens can be detected in urine from patients with serogroup 4 L. pneumophila pneumonia. Antisera were prepared in 15 rabbits and used to set up 25 solid-phase radioimmunoassays. The best of these assays detected specific antigens in urine from 4 of 5 patients with culture-proven serogroup 4 infections and from 1 of 2 patients with culture-proven serogroup 10 infections. None of 100 control specimens was positive in the assays. The antigens from serogroup 4 and 10 infections behaved differently in the assays, suggesting that they are not identical molecules. This study demonstrates that it is possible to detect specific antigens in the urine of patients with serogroup 4 L. pneumophila pneumonia. This may be a useful method for diagnosing these infections rapidly.

Animals↗

PubMed1987

Ceftizoxime and cefoxitin susceptibility testing against anaerobic bacteria: comparison of results from three NCCLS methods and quality control recommendations for the reference agar dilution procedure.

Ceftizoxime and cefoxitin (control) were tested against 99 anaerobic bacteria using three commonly used susceptibility testing methods. The cefoxitin MIC results with the National Committee for Clinical Laboratory Standards (NCCLS) reference agar dilution (RAD) method and the broth microdilution (BMD) method did not differ by more than one log2 dilution step. However, the ceftizoxime BMD MIC results were 2- to 4-fold lower than those produced by the RAD procedure. Broth disk elution (BDE) tests for both cephalosporins (ceftizoxime and cefoxitin) had very high rates of false-susceptible and false-resistant error when compared to the RAD MICs: the BDE tests are not recommended for either cephalosporin. Findings indicate that because of method and possible medium or technical variability, ceftizoxime MICs should be determined only by the NCCLS RAD method. Also, cefoxitin susceptibility should be assessed primarily by RAD or BMD procedures. This should minimize confusion related to ceftizoxime's spectrum and activity against anaerobic bacteria compared to similar beta-lactam drugs. Ceftizoxime quality control guidelines were established for Bacteroides fragilis (ATCC 25285): mode, 64 micrograms/ml, range 32-128 micrograms/ml. Other control strains were not reliable.

Agar↗

PubMed1987

DNase production by Clostridium septicum.

Sixty-two Clostridium septicum isolates were assayed for extracellular DNase activity. All of the C. septicum isolates tested produced greater DNase activity than did the other DNase-producing clostridial isolates tested. The molecular weight of the DNase of C. septicum was determined to be approximately 45,000. DNase is a major extracellular protein produced by this organism.

Clostridium↗