Health laboratory science最新文献

A new dehydrated test system (Microcult G.C.), developed by the Ames Company for the detection of Neisseria gonorrhoeae, was evaluated with stock cultures and fresh isolates. When evaluated against fresh, modified Thayer-Martin (MTM) medium, the new test was slightly less sensitive (81.6% vs 84.2% detection); however, Microcult G.C. has the unique advantage of long room-temperature storage life without deterioration. Thus, it would probably not be used where fresh MTM is readily available, proving most useful in areas where laboratory services are less accessible.

Urethral swabs from 75 males with urethritis were extracted into tryptose phosphate broth and then equal aliquots were dispensed into vials containing sucrose phosphate buffer (2SP) and urease color test medium (U-9). No antibiotics were present in the media. After transport to the laboratory, the recovery of Chlamydia trachomatis and Ureaplasma urealyticum was evaluated after inoculation into McCoy's cell cultures and agar medium, respectively. C. trachomatis was recovered from significantly more patients (17 versus 12, P = 0.03) with higher inclusion counts (P less than 0.01) in specimens transported in 2SP as compared with those in U-9 medium. No significant differences between the isolation rate of U. urealyticum and that of Mycoplasma hominis were found with the two media. The rate of inactivation of C. trachomatis and U. realyticum at 4 C was examined by means of reference strains. The inactivation of C. trachomatis was similar in both 2SP and U-9 media, but the number of inclusions was consistently greater in the 2SP medium. In contrast, the number of colony-forming units of U. urealyticum actually increased over a 24-hour period in both media. We conclude that 2SP is the best medium for the combined recovery of C. trachomatis and genital Mycoplasma. The use of one transport medium and hence a single swab culture has the obvious advantages of saving time and expense for both physician and laboratory, and for the patient it will eliminate the possible discomfort of having multiple cultures taken.

Soluble antigens were released by sonication from the cells of 60 primary cultures of Neiserria gonorrhoeae, 7 other species of neisseriae and 26 "mixed" cultures containing colonies of N. gonorrhoeae and other bacteria. Rabbits were injected with the soluble antigens of four strains of gonococci (clonal types 1 and 2), four other species of neisseriae and ten bacterial genera other than Neisseria. The antigens were tested against the non-absorbed antisera by a counter-immunoelectrophoresis method. It was found that the antiserum produced against the antigens of one N. gonorrhoeae strain, the strain GEK, reacted exclusively with the sonicates of all N. gonorrhoea cultures whether pure or mixed with other microorganisms. In contrast, the antisera to the antigens of all other N. gonorrhoeae strains cross-reacted with antigens of N. catarrhalis or N. sicca. Thus, the unique restricted reactivity of the anti-GEK antiserum permits its utilization as an immunological reagent for prompt identification of gonococcal cultures.

The incidence of antibiotic-resistant fecal coliforms in raw and treated hospital and municipal wastes was investigated to determine whether such wastes may serve as reservoirs for the spread of resistant bacteria and resistance transfer factors. Multiple resistance occurred in 87.8% of isolates from hospital and 42.6% of isolates from municipal wastes. Antibiotic resistance was transferable to Escherichia coli and Salmonella cholerae-suis recipient strains from 62.3% of resistant isolates from hospital and 90.9% of resistant isolates from municipal wastes, and from 56.2% of all isolates from hospital and 45.9% of all isolates from municipal wastes. Numbers of multiply-resistant fecal coliforms decreased during passage through a sewage treatment plant, but their proportion did not change appreciably, although proportions exhibiting resistance to 3, 4, 5, 6, and 7 drugs decreased. A study of transfer in sewage indicated that transfer of resistance from donors present in sewage to pathogenic Salmonella strains can occur under appropriate conditions. The data suggest that both raw and treated wastes, and especially those from hospitals, may serve as reservoirs for the spread of antibiotic-resistant bacteria and transferable resistance in the environment.

A significant percentage of urinary tract infections are caused by gram-positive microorganisms. The rapid identification of these uropathogens is important in determining the appropriate treatment of such infections. A selective medium containing colistin sulfate and nalidixic acid (Columbia CNA Agar) was modified by the addition of esculin, ferric ammonium citrate, mannitol and phenol red. The new medium (Esculin-Mannitol Agar) was extensively evaluated as a primary plating medium for urine specimens. Isolates were presumptively identified solely by colonial morphology and reaction of the medium. Presumptive identification of the isolates was confirmed by conventional tests. The accuracy of the presumptive identification indicated that Esculin-Mannitol Agar was useful in the primary plating of urine specimens when employed together with an appropriate medium for the recovery of gram-negative organisms.

A filter-rinse technique capable of detecting low levels of airborne hepatitis B surface antigen (HBsAg) was devised and evaluated. Laboratory tests showed the procedure to have an efficiency of 22% with a coefficient of variation of 11% and a capability of detecting as little as 5 x 10(-5) ml of aerosolized antigen positive serum in a single air sample. The technique was field-tested in a hemodialysis center serving a patient population with a high prevalence of HBsAg seropositivity. The antigen was not detected in any of 60 air samples collected under conditions favoring the occurrence of aerosols.

This study was designed to investigate the effects of viruses in the pathogenesis of Listeria monocytogenes. The organisms used in this study were: Listeria monocytogenes Type 1 isolated from a local fatal case; Mouse adapted influenza A/PR8/34 (HONI); Streptococcus pneumoniae Group B (U.M. Med. Ctr.) and poliovirus Type 2 MEF--G3M2. Balb-C mice were inoculated intraperitoneally with one LD50 of Listeria monocytogenes. Ten days later, the survivors were challenged intransally with 10 LD50 of influenza virus and observed for 14 days. Another set of Balb-C mice was inoculated intranasally with one LD50 of influenza virus and the survivors challenged 14 days later intraperitoneally with 10 LD50 of Listeria monocytogenes. Controls consisted of similar inoculation and challenge methods in mice using Streptococcus pneumoniae and polio virus with Listeria monocytogenes and influenza virus. Cross protection was observed only between Listeria monocytogenes and influenza virus. Cellular immunity may play a role in this interaction. This findings seem to agree with reports from others who showed cross protection between Listeria monocytogenes and other intracellular bacteria and parasites.

Thirty Pasteurella multocida strains were tested against 19 antibiotics using an agar dilution method. Penicillin G was the single most active agent tested. Anti-staphylococcal penicillins were markedly less inhibitory than penicillin G. Other penicillins including phenoxymethyl penicillin, and tetracyclines, chloramphenicol and cephalosporins all inhibited the organisms in low concentrations. Erythromycin and lincomycins had poor activity against several of the strains. The range of M.I.C.s observed for most antibiotics was narrow but wide variation was seen in zone size when antibiotic disk tests were performed.

The antimicrobial activity of embalming chemicals an topical disinfectants was evaluated to determine the degree of disinfection achieved during the embalming of human remains. The administration of arterial and cavity embalming chemicals resulted in a 99% reduction of the postmortem microbial population after 2 hours of contact. This level of disinfection was maintained for the 24 hours test period. Topical disinfection of the body orifices was also observed. Therefore, it is probable that present embalming practices reduce the hazard from transmission of potentially infectious microbial agents within the immediate environment of embalmed human remains.

For approximately five years the Seattle-King County Public Health Laboratory has measured its diagnostic laboratory workload quantitatively in terms of relative values. Seattle-King County has used the laboratory average cost-per-relative value concept. However, increasing operational costs, multiple demands for the same tax dollar, and professional desire for more precise costing information led the laboratory staff to refine their method of determining a cost-per-relative value. This article shares their new methodology of determining a cost-per-relative value for each primary cost center. Also shared are a few examples of how costs differ when using the old method in comparison to using the new method.