Sandra L. Aarnaes

Evaluation of five cell types for the isolation of herpes simplex virus.

Five cells were evaluated in a comparative analysis for sensitivity, specificity, and rapidity in detecting the presence of herpes simplex virus HSV-1 and HSV-2. Included in this study were human embryonic kidney (HEK), rabbit kidney (RK), MRC-5, mink lung (ML), and Microtus agrestis (UMMA). A total of 274 specimens from genital, throat, skin, or other sources that were submitted for HSV isolation were used in the study. The sensitivity of the different cells was assessed by the total number of positive cultures detected by all the cells under evaluation. At 48 hr, HEK and RK detected 80% of the positives, ML detected 79%, MRC-5 detected 73%, and UMMA detected 60%. All cells tested were satisfactory; however, the choice of which cell to use for isolation of HSV depends upon the needs of the specific laboratory.

Comparison of the ProSpecT and Color Vue enzyme-linked immunoassays for the detection of Cryptosporidium in stool specimens

Two enzyme-linked immunosorbent assays, the ProSpecT (Al-exon, Sunnyvale, CA, USA) and the Color Vue (Seradyn, Indianapolis, IN, USA) were compared for their ability to detect Cryptosporidium in 236 formalin-fixed stool specimens using the Merifluor C/G (Meridian, Cincinnati, OH, USA) stain as the reference method. The initial sensitivities of the ProSpecT and the Color Vue were 96.0% and 76.0%, which upon repeat testing of all discrepancies remained at 96.0% for the ProSpecT and decreased to 72.0% for the Color Vue. There were 25 (11%) specimens positive by the reference method. Initially, there were five false positive specimens by the ProSpecT, only one of which remained positive on retesting. The specificity of the Color Vue was 100% for the initial and repeated results, whereas the ProspecT had an initial specificity of 97.6% that increased to 99.5% upon repeat testing. The enzyme-linked immunosorbent assays offered the advantages of objectivity, batch testing, and, in the case of the ProSpecT, an acceptable sensitivity.

Evaluation of a shell vial centrifugation method for the detection of herpes simplex virus

A MRC-5 shell vial method was compared to a MRC-5 conventional tube cell culture method in 410 specimens, 88 of which were positive for herpes simplex virus. The shell vial had a sensitivity of 92% and a specificity of 99% when compared to conventional cell culture.

Evaluation of a new herpes simplex virus typing reagent for tissue culture confirmation

Monoclonal antibody typing reagents for herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2) from California Integrated Diagnostics, Inc. (Berkeley, CA) were compared to two other commercially available HSV monoclonal antibody typing reagents. Of the 105 specimens tested, of which 81 were positive for HSV, there was 100% agreement with all three typing reagents.

Rotavirus gastroenteritis in Southern California

The epidemiology of rotavirus infections in Southern California was analyzed over a three year period, from January 1, 1981 through December 31, 1983. Data was available from patients seen at the University of California Irvine Medical Center (UCIMC), in addition to referral testing provided to the community in Orange County. Over the 3 yr period the laboratory performed 1172 rotavirus assays. Out of these, 345 were positive for an overall positive rate of 29.4%. The 643 stool specimens from UCIMC corresponded to 508 patients, of which 31.1% (158/508) were positive for rotavirus. The majority of patients with a positive rotavirus test were under 1 yr of age (117/158), with only ten cases found in the 2-15 yr old group. The distribution of the positive rotavirus tests was similar for the female and male population. Approximately 70% of the positive results occur during October through December, with the month of November having the highest incidence. The distribution of positive rotavirus tests did not appear to correlate with either the coldest or the driest month of the year in Southern California.

Evaluation of the cellmatics and direct monoclonal fluorescence antibody staining for detection of genital chlamydial infections

Three methods for Chlamydia trachomatis detection were compared: the Cellmatics (Difco Laboratories, Detroit, MI), a commercially available tissue culture system which contains a rat cell line; a direct fluorescent Chlamydia antibody (DFA) (Microtrak, Syva Corp., Palo Alto, California) stain; and a standard tissue culture isolation method employing McCoy cells. Of the 121 specimens in the study, 20 were positive by the standard cell culture. All 20 of these specimens were also positive by the Cellmatics but only 10 were positive by DFA.

The Effect of Media and Temperature on the Storage of Chlamydia Trachomatis

Four media, Eagles minimal essential medium with 10% fetal bovine serum (MEM/FBS), tryptic soy broth (TSB), 2-SP, and 4-SP, were compared for their ability to maintain the viability of Chlamydia trachomatis at 4 degrees C, -20 degrees C, -70 degrees C, and -176 degrees C (liquid nitrogen) over a 1-week period. 2-SP maintained viability of C. trachomatis to the greatest extent for all of the time intervals and temperatures examined. Therefore, in an attempt to further stabilize the viability of C. trachomatis, 2-SP was supplemented with various concentrations of bovine serum albumin (BSA) or fetal bovine serum (FBS). For the times and temperatures examined, 2-SP supplemented with 20% or 40% FBS or 5% BSA preserved infectivity to a greater extent than unsupplemented 2-SP. In some supplemented media, up to 65% of the infectivity was preserved after one week of storage at -176 degrees C, whereas only 0-3% of infectivity remained when stored in unsupplemented media at -20 degrees C and 4 degrees C, respectively. Therefore, supplementation of 2-SP with FBS or BSA can prolong the survival of chlamydia, which is critical in the transportation and storage of clinical specimens. In addition, storage for prolonged periods of time should be at -70 degrees C or lower temperatures.