A case-control study of HIV seroconversion in health care workers after percutaneous exposure. Centers for Disease Control and Prevention Needlestick Surveillance Group.

BACKGROUND: The average risk of human immunodeficiency virus (HIV) infection after percutaneous exposure to HIV-infected blood is 0.3 percent, but the factors that influence this risk are not well understood. METHODS: We conducted a case-control study of health care workers with occupational, percutaneous exposure to HIV-infected blood. The case patients were those who became seropositive after exposure to HIV, as reported by national surveillance systems in France, Italy, the United Kingdom, and the United States. The controls were health care workers in a prospective surveillance project who were exposed to HIV but did not seroconvert. RESULTS: Logistic-regression analysis based on 33 case patients and 665 controls showed that significant risk factors for seroconversion were deep injury (odds ratio= 15; 95 percent confidence interval, 6.0 to 41), injury with a device that was visibly contaminated with the source patient's blood (odds ratio= 6.2; 95 percent confidence interval, 2.2 to 21), a procedure involving a needle placed in the source patient's artery or vein (odds ratio=4.3; 95 percent confidence interval, 1.7 to 12), and exposure to a source patient who died of the acquired immunodeficiency syndrome within two months afterward (odds ratio=5.6; 95 percent confidence interval, 2.0 to 16). The case patients were significantly less likely than the controls to have taken zidovudine after the exposure (odds ratio=0.19; 95 percent confidence interval, 0.06 to 0.52). CONCLUSIONS: The risk of HIV infection after percutaneous exposure increases with a larger volume of blood and, probably, a higher titer of HIV in the source patient's blood. Postexposure prophylaxis with zidovudine appears to be protective.

Percutaneous exposures to HIV-infected blood. Among dental workers enrolled in the CDC Needlestick Study.

The authors found that 19 percutaneous exposures among dental workers occurred both during and after use of instruments such as syringe needles and scalers. Specific information about the device and action associated with an exposure is important for prevention efforts, including safer instruments and work practices. Most of these exposures probably involved smaller, rather than larger, amounts of blood infected with the human immunodeficiency virus. To our knowledge, none of the exposures resulted in HIV transmission to an enrolled dental worker.

Occupational blood contact among prehospital providers.

STUDY OBJECTIVE: To assess the nature and frequency of blood contact (BC) among emergency medical service (EMS) workers. DESIGN: During an 8-month period, we interviewed EMS workers returning from emergency transport calls on a sample of shifts. We simultaneously conducted an HIV seroprevalence survey among EMS-transported patients at receiving hospitals served by these workers. SETTING: Three US cities with high AIDS incidence. PARTICIPANTS: EMS workers. RESULTS: During 165 shifts, 2,472 patients were attended. Sixty-two BCs (1 needlestick and 61 skin contacts) were reported. Individual EMS workers had a mean of 1.25 BCs, including .02 percutaneous exposures, per 100 patients attended. The estimated annual frequency of BC for an EMS worker at the study sites was 12.3, including .2 percutaneous exposures. For 93.5% of the BCs, the HIV serostatus of the source patients was unknown to the EMS worker. HIV seroprevalences among EMS-transported patients at the three receiving hospital emergency departments were 8.3, 7.7, and 4.1 per 100 patients; the highest rates were among male patients 15 to 44 years old who presented with pneumonia. CONCLUSION: EMS personnel regularly experience BCs, most of which are skin contacts. Because the HIV serostatus of the patient is usually unknown, EMS workers should practice universal precautions. Postexposure management should include a mechanism for voluntary HIV counseling and testing of the patient after transport and transmittal of the results to the EMS.

Investigations of patients of health care workers infected with HIV. The Centers for Disease Control and Prevention database.

OBJECTIVE: To assess the risk for transmission of the human immunodeficiency virus (HIV) from an infected health care worker to patients. DESIGN: Survey of investigators from health departments, hospitals, and other agencies who had elected to notify patients who had received care from health care workers infected with HIV. MEASUREMENTS: Information was collected about infected health care workers, their work practices, their patients' HIV test results, procedures that they did on those of their patients who were tested for HIV, and patient notification procedures. RESULTS: As of 1 January 1995, information about investigations of 64 health care workers infected with HIV was reported to the Centers for Disease Control and Prevention; HIV test results were available for approximately 22,171 patients of 51 of the 64 health care workers. For 37 of the 51 workers, no seropositive patients were reported among 13,063 patients tested for HIV. For the remaining 14 health care workers, 113 seropositive patients were reported among 9108 patients. Epidemiologic and laboratory follow-up did not show any health care worker to have been a source of HIV for any of the patients tested. CONCLUSION: Despite limitations, these data are consistent with previous assessments that state that the risk for transmission of HIV from a health care worker to a patient is very small. These data also support current recommendations that state that retrospective patient notification need not be done routinely.

Use of Presumpto Plates to identify anaerobic bacteria.

Identification of anaerobic bacteria requires special media and growth conditions that contribute to a higher cost per identification than that for aerobic isolates. Newer rapid methods streamline the identification process, but confirmation to the species level is often difficult. The Presumpto Plate method for the identification of commonly encountered anaerobes consists of three quadrant plates, each containing four conventional media, that result in the generation of 21 test parameters: growth on Lombard-Dowell medium; production of indole, indole derivative, catalase, lecithinase, and lipase; proteolysis of milk, H2S, and esculin; growth on 20% bile; precipitate on bile; DNase, glucose, casein, starch, and gelatin hydrolysis; and fermentation of lactose, mannitol, and rhamnose. Identification charts were developed by using the results from 2,300 anaerobic isolates. Because conventional media were used, there was a high degree of agreement between the Presumpto Plate method and the reference method when testing commonly encountered anaerobes. The Presumpto Plate method is as accurate as commercially available enzyme systems for the identification of many anaerobic species but is less expensive to perform.

Serosurvey of human immunodeficiency virus, hepatitis B virus, and hepatitis C virus infection among hospital-based surgeons. Serosurvey Study Group.

BACKGROUND: Because occupational blood contact places health-care workers at risk for infection with bloodborne pathogens, we wanted to estimate the prevalence of infection with human immunodeficiency virus (HIV), hepatitis B virus (HBV), and hepatitis C virus (HCV) among hospital-based surgeons and correlate the results with occupational and nonoccupational risk factors. STUDY DESIGN: All surgeons in training or in practice in general surgery, obstetrics and gynecology, or orthopedics at 21 hospitals in moderate to high AIDS incidence areas were eligible to participate in a voluntary, anonymous serosurvey. Serum samples were tested for HIV antibody, for HCV antibody, and for markers of HBV infection: hepatitis B surface antigen, total antibody to hepatitis B core antigen, and antibody to hepatitis B surface antigen. RESULTS: Of 2,887 eligible surgeons, 770 (27 percent) participated in the study. One of 740 surgeons not reporting nonoccupational risk factors was HIV seropositive (0.14 percent, upper limit 95 percent confidence interval [CI] equals 0.64 percent). None of 20 participants reporting nonoccupational HIV risk factors and none of ten not responding to the question on nonoccupational risk factors were HIV positive. Of 129 (17 percent) participants with past or current HBV infection, three (0.4 percent) had chronic HBV infection; all were negative for hepatitis B e antigen. Risk factors for HBV infection included not receiving hepatitis B vaccine (odds ratio [OR] 14.7, 95 percent CI 8.3 to 26.0) and practicing surgery at least ten years (OR 2.2, 95 percent CI 1.3 to 3.8). Seven (0.9 percent) participants had anti-HCV. CONCLUSIONS: Although not necessarily generalizable to all surgeons in moderate to high AIDS incidence areas, these results do not indicate a high rate of previously undetected HIV infection among surgeons who trained or practiced in these areas, or both. Hepatitis B virus posed the highest risk of infection with a bloodborne pathogen, followed by HCV and HIV.

Risk of human immunodeficiency virus infection among emergency department workers.

PURPOSE: To estimate (1) the prevalence of human immunodeficiency virus (HIV) infection in emergency department (ED) patients, (2) the frequency of blood contact (BC) in ED workers (EDWs), (3) the efficacy of gloves in preventing BC, and (4) the risk of HIV infection in EDWs due to BC. PATIENTS AND METHODS: We conducted an 8-month study in three pairs of inner-city and suburban hospital EDs in high AIDS incidence areas in the United States. At each hospital, blood specimens from approximately 3,400 ED patients were tested for HIV antibody. Observers monitored BC and glove use by EDWs. RESULTS: HIV seroprevalence was 4.1 to 8.9 per 100 patient visits in the 3 inner-city EDs, 6.1 in 1 suburban ED, and 0.2 and 0.7 in the other 2 suburban EDs. The HIV infection status of 69% of the infected patients was unknown to ED staff. Seroprevalence rates were highest among patients aged 15 to 44 years, males, blacks and Hispanics, and patients with pneumonia. BC was observed in 379 (3.9%) of 9,793 procedures; 362 (95%) of the BCs were on skin, 11 (3%) were on mucous membranes, and 6 (2%) were percutaneous. Overall procedure-adjusted skin BC rates were 11.2 BCs per 100 procedures for ungloved workers and 1.3 for gloved EDWs (relative risk = 8.8; 95% confidence interval = 7.3 to 10.3). In the high HIV seroprevalence EDs studied, 1 in every 40 full-time ED physicians or nurses can expect an HIV-positive percutaneous BC annually; in the low HIV seroprevalence EDs studied, 1 in every 575. The annual occupational risk of HIV infection for an individual ED physician or nurse from performing procedures observed in this study is estimated as 0.008% to 0.026% (1 in 13,100 to 1 in 3,800) in a high HIV seroprevalence area and 0.0005% to 0.002% (1 in 187,000 to 1 in 55,000) in a low HIV seroprevalence area. CONCLUSIONS: In both inner-city and suburban EDs, patient HIV seroprevalence varies with patient demographics and clinical presentation; the infection status of most HIV-positive patients is unknown to ED staff. The risk to an EDW of occupationally acquiring HIV infection varies by ED location and the nature and frequency of BC; this risk can be reduced by adherence to universal precautions.