Health laboratory science最新文献

The New York State Department of Health proficiency testing program in mycobacteriology determines the ability of a laboratory to isolate the acid-fast bacillus present in a simulated specimen and to identify the strain. Until 1964 the specimens were autoclaved normal sputa seeded with mycobacteria. When mandatory testing was introduced by law in 1964, more specimens were needed. These have been prepared in simulated sputum bases, first skimmed milk, then granulated hog gastric mucin. The bases are seeded with Mycobacterium tuberculosis and other mycobacteria; Pseudomonas aeruginosa is added to simulate the contamination in clinical specimens. Laboratory performance in general has improved as a result of the proficiency testing and the concomitant educational program, but laboratories processing more than 200 specimens a year continue to perform best.

The Becton-Dickinson VACUTAINER BRAND SERUM SEPARATOR TUBE (SST) was evaluated in a field test in five hospitals. The SST evacuated blood drawing tube contains a semi-solid silicon polymer which migrates to the serum-clot interface during centrifugation causing a barrier to form which separates serum from red cells. Eighteen clinical chemistry determinations were studied. No clinically significant SST induced changes were observed when compared to conventional blood drawing tubes. Statistically significant changes (t-test, p=0.05) were observed for bicarbonate, calcium, chloride, cholesterol, glucose (Beckman Analyzer), and sodium. For each test (glucose, uric acid, etc.) data were analyzed twice; once as a complete set, and once as a subset consisting of abnormal data only. The small, statistically significant LDH bias observed in the earlier (2,3) clinical trials was not present.

Cultures of the cervix and rectum are recommended for the routine diagnosis of gonorrhea in women. Specimens are usually inoculated on separate plates of selective medium. The present study compares to the recovery rates of N. gonorrhoeae for cervical and rectal specimens plated separately to specimens combined on a single plate of modified Thayer-Martin medium (MTM). No statistically significant difference was detected between the two methods. It is concluded that the practice of combining cervical and rectal specimens on a single MTM plate provides the sensitivity of separately plated specimens at half the cost. Combining specimens could provide a significant cost benefit to gonorrhea control programs.

Application of bat guano to an area with reduced but detectable colonization by Histoplasma capsulatum had no quantitative effect on the fungus. After seeding the guano treated area and an untreated area with a soil culture of the fungus, a quantitative effect was noted in the treated area but the period of survival did not appear to be extended. Twenty-four months after seeding, the fungus was no longer detectable in the study areas and they have remained negative for more than a year.

Sera from the salt water fish (Yellow tail flounder) and the fresh water fish (rainbow trout) were tested for the presence of circulating antibodies against nine strains of Vibrio parahaemolyticus and one of V. alginolyticus. Thirteen out of 26 flounder sera tested gave agglutinating reactions against one specific strain of V. parahaemolyticus; strain No. 3525. Seven rainbow trout sera tested failed to agglutinate any of the strains tested. All agglutinating activity was lost upon boiling the antigen, therefore, the fish antibodies are due to surface antigens (K-antigens) and not to somatic antigens. The specific V. parahaemolyticus strain No. 3525 belongs to the serological type 03:K30, which might be common to the sea waters of the Eastern United States. The possibility that fish serve as a reservoir to Vibrio parahaemolyticus and its possible implication in the transmission of human disease are discussed.

Except in gas production, S. flexneri 6 is generally similar to other S. flexneri. S. flexneri 6 contains both aerogenic and anaerogenic strains which are identical serologically. It is not surprising that S. flexneri 6 is not separable from other S. flexneri types on the basis of DNA relatedness (overall genetic makeup) (4). The Manchester biotype is seen in the United States, and is easily separable from other Enterobacteriaceae by biochemical tests. One can no longer assume à priori that any given biochemical reaction rules an organism out of Shigella. This is particularly true for the production of gas from glucose, but also applies to the fermentation of lactose and the production of H2S. Clinical laboratory personnel should be alert to these possibilities.

With the change in the management of tuberculosis, many bacteriology laboratories should be prepared to examine sputum for the presence of acid-fast bacilli. The niacin test is the most reliable test that can be performed in any mycobacteriology laboratory to differentiate Mycobacterium tuberculosis from the other acid-fast bacilli, but it is not perfect. Other tests can be used to supplement it are cord formation, growth at 24 C, and the catalase test at 68 C. Incompletely identified strains should be submitted to a reference laboratory.

Rabies immunofluorescence in glycerol-preserved tissues is more intense without acetone fixation. Glycerol preservation of suspected rabid tissue should be avoided whenever possible.

NYC medium supplemented with cow blood (NYC-C) and sheep blood (NYC-S) were tested for the growth of N. gonorrhoeae and urogenital mycoplasma in comparison with standard NYC medium which contains horse blood. In situations where horse blood is not available, cow blood could be substituted in NYC standard medium, whereas the use of sheep blood was found unsuitable.

Mycoplasmas have been well established as pathogens of the bovine urogenital tract, and produce pathologic lesions resulting in infertility. Serologic examination of cattle with infertility problems with Mycoplasma bovigenitalium and Mycoplasma agalactiae subsp. bovis show a high incidence of positive reactors suggesting that mycoplasmas play an important role in bovine infertility. The similarities of pathologic lesions in the urogenital tract of cattle and women with infertility problems and the frequency of isolation of mycoplasmas from human females suggest closer examination for mycoplasmas in human infertility. Studies with bulls suggest that mycoplasmas as a cause of human male infertility should not be ignored.