Biomedical subjects
Publications and source records attributed to C H Sherlock.
A laboratory model of herpes simplex virus infection was used to assess the potential contamination of dental handpieces. When contaminated instruments were treated with surface disinfection and internal chemical disinfection, viable virus was eliminated in all instruments.
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Two common tissue sampling techniques--colposcopic biopsy and cervical scrape--and two common human papillomavirus (HPV) detection techniques--Southern blot and dot blot (SB and ViraPap [VP])--were compared to determine whether differences in these techniques alter correlations between "oncogenic" HPVs and cervical neoplasia. In 87 women with persistently abnormal Papanicolaou (Pap) smears, concurrent biopsy and scrape specimens contained HPV in 21 (24%) and contained no HPV in 26 (30%); 30 scrape specimens (34.5%) tested positive when the biopsy tested negative and 10 (11.5%) scrape specimens tested negative when the biopsy tested positive (overall concordance, 54%). Concordance for the most prevalent HPVs (16/18) was 59%. In carcinoma in situ, HPV was found in biopsy samples significantly more frequently than in scrape specimens: 17 of 23 (75%) biopsy samples versus 9 of 23 (39%) scrape specimens (P = 0.018). Conversely, in mild or no dysplasia, 0 of 42 biopsy samples tested positive for HPV 16/18 compared with 12 of 42 scrape specimens (29%; P = 0.0001). Of 229 specimens analyzed by SB and VP, 43 (19%) tested positive and 148 (65%) tested negative for HPV by both methods (concordance, 84%). Corroborative results indicated that 29 of 35 (83%) VP-positive SB-negative results were truly positive compared with none of three SB-positive VP-negative results. Both the cervical sampling technique and the method for HPV detection can significantly affect statistical correlations between cervical dysplasia and HPV type.
Bone marrow transplantation (BMT) may change the recipient's pretransplant serostatus for herpes group viruses. We reviewed 68 patient records (1 year's transplants) to determine how frequently this occurs. Only 7 had data on serostatus before as well as at days 20 to 35 and greater than 100 after BMT. Serostatus was assessed by complement fixation and ELISA. All patients received a variety of blood-product support after BMT. One patient converted from anti-varicella zoster virus (VZV) positive to negative after BMT and developed clinical chickenpox; an additional patient converted from anti-VZV negative to positive after BMT but reverted to seronegative by day 102. One patient converted from anti-cytomegalovirus (CMV) positive pre-BMT to persistently anti-CMV negative post-BMT (donor: anti-CMV negative). Two patients had a greater than 4-fold fall in anti-herpes simplex (HSV) antibody post-BMT, and both shed HSV after BMT. Most seronegative recipients of marrow from seropositive donors developed herpesvirus antibodies. We conclude that the herpesvirus serostatus of BMT recipients should be determined again after BMT to aid in decisions about antiviral prophylaxis and diagnosis of clinical disease.
Hairy leukoplakia (HL) also occurs in immunosuppressed post-bone-marrow transplantation patients, and in the presence or absence of Epstein-Barr virus. It may not always be diagnostic of HIV positivity. However, HIV status should still be determined in patients with HL.
We studied the role played by CMV in kidney transplant rejection by recording serological responses to CMV replication in cadaver graft recipients and recording clinical graft rejection by monitoring acute changes in renal function and the appearance of antidonor lymphocyte antibody (anti-Dab). If CMV plays a significant role in rejection, clinical rejection should correlate with CMV activity; if CMV does not play a role, clinical rejection would be likely to correlate with anti-Dab but not necessarily with CMV activity. We selected retrospectively 18 rejectors and 18 nonrejectors by clinical criteria and assayed for anti-Dab (by fluorescence-activated flow cytometry) and CMV antibody (by complement fixation and Western blot for IgG and IgM) over a 3-6-month period after transplantation. Primary CMV infection occurred in 8 of 12 (67%) CMV seronegative graft recipients and reactivation or reinfection occurred in 16 of 24 (67%); 12 of 14 (86%) rejectors developed anti-Dab compared with 2 of 18 (11%) nonrejectors (P less than 0.00001). Active CMV infection occurred in 11 of 18 (61.1%) rejectors and 13 of 18 (72.2%) nonrejectors (P = 0.36), and in 8 of 15 (53.3%) of those who developed anti-Dab and 12 of 17 (70.6%) of those who did not (P = 0.26). The results show no evidence to link CMV activity with kidney graft rejection.
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Weekly cultures of stools from neutropenic patients and bone marrow transplant recipients yielded Aeromonas hydrophila from 8% of 88 patients over a 2-yr period. During this time stools in the routine enteric laboratory yielded A. hydrophila in 0.24% of 1632 patients. Although the patient groups and culture methods were not directly comparable, this significant difference in isolation rate (p less than 0.001) may reflect a higher colonization rate in the immunocompromised patient.
A commercially available latex agglutination test for Clostridium difficile was compared with a cell culture cytotoxin assay and bacteriological culture for the laboratory diagnosis of C. difficile-associated diarrhea and colitis (CAD). Stool specimens from 626 patients were tested by the three methods, and specimens from 118 patients (19%) were positive by at least one of the methods. The results of the three tests agreed in 88% of the specimens tested, overall, but they agreed in only 34% of the 118 positive specimens. Ninety-three patients were evaluated to assess the significance of positive and negative results for each assay. Of 40 patients found to have CAD, 70% were positive by the cytotoxin assay, 78% were positive by the latex agglutination test, and 90% were culture positive. Of 53 patients who did not have CAD, 2% were positive by the cytotoxin assay, 8% were positive by the latex test, and 4% were culture positive. The detection of CAD was improved by using the tests in combination, and 97% of specimens positive by two or three methods were from patients who had CAD. Testing of multiple specimens from individual patients also increased the sensitivity of detection of CAD. The results suggest that the latex agglutination test may be useful for rapid diagnosis of CAD, especially in laboratories that lack cell culture facilities. However, the accuracy of CAD detection is improved when the latex test is used in combination with culture or the cytotoxin assay.
We evaluated the type specificity of complement-fixing (CF) antibody against the AG-4 early antigen of herpes simplex virus (HSV) type 2 (HSV-2) by comparing a commercial AG-4 CF kit (Simplex-2; Gene Link Australia, Inc., Princeton, N.J.) with quantal microneutralization (MN) and absorption-Western blotting in testing sera from patients with and without a history of genital herpes. Sera characterized as HSV type 1 (HSV-1) or HSV-2 positive or negative by MN were selected and tested by CF, and those with discordant results were further analyzed for specific antibodies by absorption with HSV-1 or HSV-2 antigen and Western blotting with heterologous HSV proteins. A total of 34 of 42 (81%) sera HSV-2 positive by MN, 19 of 43 (44%) sera HSV-1 positive by MN, and 0 of 19 sera negative by MN were positive by CF. Absorption-Western blotting showed that 12 of 18 (67%) sera HSV-1 positive by MN but positive by CF had no HSV-2-specific antibody and that all 7 sera HSV-2 positive by MN but negative by CF had HSV-2-specific antibody. When MN and absorption-Western blotting data were combined to analyze patients with no history of genital herpes, 7 of 19 (37%) with no HSV-2-specific antibody were positive by CF, and 7 of 27 (26%) with HSV-2-specific antibody were negative by CF. The positive and negative predictive values for the CF test were 78 and 75%, respectively, in this group. The presence of antibody to the HSV AG-4 antigen does not discriminate sufficiently between HSV-1- and HSV-2-infected patients to be of value in predicting HSV-2 infection in the absence of symptomatic disease.
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This study was undertaken to develop an accurate, yet inexpensive, method for determining whether the bowel of a neutropenic patient is colonized with bacteria resistant to the antimicrobial agents used in empiric therapy. Selective agar media were prepared in which Mueller-Hinton agar or MacConkey agar were supplemented with one of the following antimicrobial agents: carbenicillin (16 micrograms/ml), gentamicin (4 micrograms/ml), or tobramycin (4 micrograms/ml). Moxalactam was incorporated initially at 16 micrograms/ml and subsequently at 8 micrograms/ml. Stools from neutropenic patients and bone marrow transplant recipients were inoculated on these media and on unsupplemented MacConkey agar. All bacteria that grew on the antibiotic-containing media were categorized as resistant to the supplementing drug; failure to detect an organism that did grow on the antibiotic-free MacConkey agar indicated susceptibility. These results were compared with those obtained for all isolates on all media by agar disk diffusion. There were 512 gram-negative enteric isolates from 320 stools obtained from 98 patients. The antibiotic-containing media suppressed the growth of 95% of bacteria that were identified as susceptible by agar disk diffusion. In detecting resistant organisms, the correlation between agar disk diffusion and direct stool screening with Mueller-Hinton agar ranged from 73 to 83%, and on MacConkey agar it ranged from 87 to 97%. The predictive value of a resistant result was 80 to 97% for the four antimicrobial agents when MacConkey agar was used. MacConkey agar performed better than Mueller-Hinton agar because of the greater ease of detecting different bacterial morphotypes. The cost of direct stool screening with antibiotic-supplemented MacConkey agar is approximately half the cost of routine methods of surveillance. Its cost and accuracy make the method a useful adjunct to the routine management of neutropenic patients.
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