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Biomedical subjects

L Hofherr

Publications and source records attributed to L Hofherr.

13 recordsLinked to original sources
PubMed1979

Comparison of the API 20E and Corning N/F systems for identification of nonfermentative gram-negative rods.

A total of 231 strains of nonfermenting gram-negative rods were tested on the API 20E system, the Corning N/F system, and conventional media. When the results of identification to species were compared, the API system agreed with the conventional system on 69% of the isolates, and the Corning system agreed with the conventional system on 79% of the isolates. Both kit systems were deficient in identifying Pseudomonas cepacia and the more unusual isolates.

Bacterial Infections↗
PubMed1979

A broth-disc technique for the assay of antibiotic synergism.

A broth-disc technique has been developed to demonstrate the antibiotic synergism of some broad-spectrum penicillins plus an aminoglycoside against Pseudomonas aeruginosa and enterococci. Utilizing the zone sites obtained from Kirby-Bauer susceptibility tests, approximate minimum inhibitory concentrations of each antibiotic upon individual isolates were derived using standard regression curves. One-fourth of each value was calculated and the approximate desired concentration then prepared in Mueller-Hinton broth through use of the labelled antibiotic disc content. Tubes were inoculated with a standardized suspension of organism and incubated at 35 degrees C for 18-24 h. Subsequently, inhibitory end points were recorded. This approach to synergy testing showed good correlation with the standard checkerboard method. The broth-disc synergistic assay is also reproducible, financially feasible, and less time-consuming to execute.

Amikacin↗
PubMed1979

Characterization of staphylococci using the API 20E system.

Fifty-four strains of coagulase-negative staphylococci, five isolates of coagulase-positive staphylococci, and seven species of Micrococcus were tested in the API 20E system. After 48 hours' incubation, results indicated that the various species and subgroups could be separated by their reactions. Staphylococcus saphrophyticus subgroup 3 was ONPG and mannitol positive. S. epidermidis subgroup 1 was positive for arginine dihydrolase (ADH), whereas S. epidermidis subgroup 4 was positive for ADH, mannitol, and arabinose. S. aureus coagulase negative was characterized by positive ONPG, ADH, and mannitol. In contrast, S. aureus coagulase positive was not positive for ONPG but was positive for ADH and mannitol. Most of these staphylococci were able to utilize nitrates, urea, glucose, and sucrose. The micrococci, on the other hand, gave varied reactions, with most species being only weakly reactive.

Bacteriological Techniques↗
PubMed1978

Comparison of three methods for identifying nonfermenting gram-negative rods.

Seventy-six strains of nonfermenting gram-negative rods were tested on the Analytab Products, Inc. (API) system and on conventional media. In addition, 51 strains were tested on the Oxi-Ferm system. When the identification results were compared, the API agreed with the conventional system on 41% of the isolates and Oxi-Ferm agreed with the conventional system on 72% of the isolates. API had the greatest difficulty in identifying Pseudomonas aeruginosa. API and Oxi-Ferm both had difficulty identifying P. cepacia. Oxi-Ferm had more individual discrepant biochemical reactions than did API when compared to the conventional media, but still maintained a higher percentage agreement with the conventional system.

Bacterial Infections↗
PubMed1978

Evaluation of the Microcult-GC kit as a screening method for the detection of Neisseria gonorrhoeae.

The Microcult-GC Kit was compared to the standard modified Thayer-Martin plate method for the isolation and presumptive identification of Neisseria gonorrhoeae. Two hundred and thirty specimens representing urethral, endocervical, rectal, and pharyngeal sites were inoculated to both media. If only genital and rectal cultures were compared, the overall agreement was 98 percent, with a false positive rate of 1/145 (0.7 percent) and a false negative rate of 2/145 (1.4 percent). However, in the pharyngeal cultures, 16 of 32 gave false positives, thus emphasizing the manufacturer's instructions to limit the kit's use to genital and rectal cultures. The kit system gives rapid presumptive results, has a long shelf life at room temperature, and needs little laboratory equipment for proper use.

Bacteriological Techniques↗
PubMed1978

Use of case histories in teaching clinical microbiology.

In the Winter Quarter, 1977, case histories were introduced into the Diagnostic Microbiology course of the Medical Technology curriculum at the University of Minnesota. The primary goal was to increase the students' exposure to patients and patients' illnesses and to emphasize the role and responsibilities of technologists and clinical laboratories to these patients. This goal seems to have been met as indicated by an evaluation received from the students, since 58.3 percent believed they better understood the role of the technologist and clinical laboratory in patient care. Other side benefits we hoped to achieve seem to have been partially met. These included: 1) association of infectious processes with other laboratory results; 2) a feeling of integration with the patient and health care team; and 3) the introduction of medical terminology.

Medical Laboratory Science↗