Extended-spectrum beta-lactamase-producing Klebsiella pneumoniae in a neonatal intensive care unit: risk factors for infection and colonization

An outbreak of extended spectrum beta-lactamase-producing Klebsiella pneumoniae (ESBLKp) infections in a neonatal intensive care unit (NICU) prompted a prospective investigation of colonization and infection with this pathogen. From August 1, 1997 to May 30, 1999, neonates admitted to the NICU for more than 24 h were screened for ESBLKp acquisition. Neonatal gastrointestinal screening was performed by means of faecal sampling within 48 h of admission and then weekly until discharge. Isolates were typed using pulsed-field gel electrophoresis (PFGE). Time-dependent proportional hazard models were used to identify independent effects of invasive procedures and antimicrobials after controlling for duration of stay at the NICU. During the study period, 464 neonates were admitted and 383 were regularly screened. Infections occurred in 13 (3.4%) neonates and 206 (53.8%) became colonized. Independent risk factors for colonization during the first nine days in the NICU were the antimicrobial combination cephalosporin plus aminoglycoside [hazard rate (HR)=4.60; 95% CI: 1.48-14.31], and each NICU-day was associated with a 26% increase in the hazard rate for colonization (HR=1.26; 95% CI: 1.16-1.37). Previous colonization (HR=5.19; 95% CI: 1.58-17.08) and central vascular catheter use (HR=13.89; 95% CI: 2.71-71.3) were independent risk factors for infection. In an outbreak setting the proportion of neonates colonized with ESBLKp was observed to increase with the duration of stay and antimicrobial use, and once colonized, infants exposed to invasive devices may become infected.

Issues and opportunities in public health informatics: a panel discussion

A panel was convened at the American Medical Informatics Association Spring Congress to discuss issues and opportunities that arise when informatics methods, theories, and applications are applied to public health functions. Panelists provided examples of applications that connect efforts between public health and clinical care, emphasizing the need for integration of clinical data with public health data and the analysis of those data to support surveillance and informed decision making. Benefits to be gained by both medical informatics and public health at the interface were evident; both encounter the same major issues including privacy, systems integration, standards, and many more.

HIV incidence among repeat HIV testers at a county hospital, San Francisco, California, USA

OBJECTIVES

To estimate HIV incidence, characterize correlates of HIV seroconversion, and monitor temporal trends in HIV transmission among patients repeatedly tested for HIV by a county hospital in San Francisco.

DESIGN

Retrospective longitudinal study.

METHODS

HIV incidence was retrospectively calculated among persons voluntarily tested for HIV antibody more than once at San Francisco's county hospital or one of its affiliated satellite community clinics between 1993 and 1999. Linkage of HIV test results in computerized databases identified "seroconverters" as individuals who had a negative antibody test followed by a positive test. The interval between tests was used as the person-time at risk. Cox proportional hazards analysis identified correlates of HIV seroconversion.

RESULTS

A total of 84 HIV seroconversions were identified among 2893 eligible patients repeatedly tested for HIV antibody over a cumulative 5860 person-years (PYs) (incidence of 1.4 per 100 PYs, 95% confidence interval [CI]: 1.2-1.7). The majority of seroconversions (71 [84.5%]) were among injection drug users (IDUs) (incidence of 2.0 per 100 PYs, CI: 1.6-2.4). HIV incidence was highest among men who have sex with men (MSM) who were also IDUs (incidence of 3.8 per 100 PYs, CI: 2.7-5.1) and lowest among non-IDUs, heterosexual men, and non-IDU women (incidence of 0.3 per 100 PYs, CI: 0.1-0.6). In multivariate analysis, correlates of HIV seroconversion were age 25 to 29 years (hazard ratio [HR] = 3.9, CI: 2.4-6.3), MSM (HR = 2.9, CI: 1.9-4.4), and IDU (HR = 3.2, CI: 1.8-5.8). Overall, no temporal trend in annual HIV incidence was noted during the study period; however, HIV incidence among MSM IDUs increased from 2.9 per 100 PYs in 1996 to 4.7 per 100 PYs in 1998.

CONCLUSIONS

The rate of seroconversion in this hospital and affiliated clinic population is unexpectedly high. Moreover, HIV transmission among IDU patients has not decreased over the last several years. The San Francisco county hospital provides a high-risk sentinel population to monitor emerging trends in HIV transmission, especially among IDUs, and presents multiple opportunities for prevention interventions, because these patients are being seen repeatedly by clinicians.

Health-care quality promotion through infection prevention: beyond 2000

Health-care value purchasing, complex health-care systems, and information technology are the three most important change drivers influencing the interrelated themes of the 4th decennial conference: accountability, quality promotion through infection prevention across the health-care delivery system, and medical informatics. Among the change drivers influencing themes of future conferences may be a societal mandate for health promotion and health-care access for all.

Bioterrorism-related inhalational anthrax: the first 10 cases reported in the United States

From October 4 to November 2, 2001, the first 10 confirmed cases of inhalational anthrax caused by intentional release of Bacillus anthracis were identified in the United States. Epidemiologic investigation indicated that the outbreak, in the District of Columbia, Florida, New Jersey, and New York, resulted from intentional delivery of B. anthracis spores through mailed letters or packages. We describe the clinical presentation and course of these cases of bioterrorism-related inhalational anthrax. The median age of patients was 56 years (range 43 to 73 years), 70% were male, and except for one, all were known or believed to have processed, handled, or received letters containing B. anthracis spores. The median incubation period from the time of exposure to onset of symptoms, when known (n=6), was 4 days (range 4 to 6 days). Symptoms at initial presentation included fever or chills (n=10), sweats (n=7), fatigue or malaise (n=10), minimal or nonproductive cough (n=9), dyspnea (n=8), and nausea or vomiting (n=9). The median white blood cell count was 9.8 X 10(3)/mm(3) (range 7.5 to 13.3), often with increased neutrophils and band forms. Nine patients had elevated serum transaminase levels, and six were hypoxic. All 10 patients had abnormal chest X-rays; abnormalities included infiltrates (n=7), pleural effusion (n=8), and mediastinal widening (seven patients). Computed tomography of the chest was performed on eight patients, and mediastinal lymphadenopathy was present in seven. With multidrug antibiotic regimens and supportive care, survival of patients (60%) was markedly higher (<15%) than previously reported.

Clinical infection control in gene therapy: a multidisciplinary conference

Gene therapy is being studied for the treatment of a variety of acquired and inherited disorders. Retroviruses, adenoviruses, poxviruses, adeno-associated viruses, herpesviruses, and others are being engineered to transfer genes into humans. Treatment protocols using recombinant viruses are being introduced into clinical settings. Infection control professionals will be involved in reviewing the safety of these agents in their clinics and hospitals. To date, only a limited number of articles have been written on infection control in gene therapy, and no widely available recommendations exist from federal or private organizations to guide infection control professionals. The goals of the conference were to provide a forum where gene therapy experts could share their perspectives and experience with infection control in gene therapy and to provide an opportunity for newcomers to the field to learn about issues specific to infection control in gene therapy. Recommendations for infection control in gene therapy were proposed.

Emergence of trimethoprim-sulfamethoxazole resistance in the AIDS era

Trimethoprim-sulfamethoxazole (TMP-SMX) is widely used for Pneumocystis carinii pneumonia prophylaxis in human immunodeficiency virus (HIV)-infected patients, but little is known about the effects of this practice on the emergence of TMP-SMX-resistant bacteria. A serial cross-sectional study of resistance to TMP-SMX among all clinical isolates of Staphylococcus aureus and 7 genera of Enterobacteriaceae was performed at San Francisco General Hospital. Resistance among all isolates was <5.5% from 1979 to 1986 but then markedly increased, reaching 20.4% in 1995. This was most prominent in HIV-infected patients: resistance increased from 6.3% in 1988 to 53% in 1995. The largest increases in resistance were in Escherichia coli (24% in 1988 to 74% in 1995) and S. aureus (0% to 48%) obtained from HIV-infected patients. A rapid increase in the use of prophylactic TMP-SMX in HIV disease was also observed during this time in San Francisco and is likely responsible for the increase in TMP-SMX resistance.

Post-exposure prophylaxis for HIV

The advent of preventive treatment for HIV highlights the urgent need for basic, clinical, and epidemiologic research targeting the pathogenesis and prevention of cutaneous and mucosal infection. In addition, the impact of HIV prophylaxis on the frequency of risk behaviors and antiretroviral drug resistance, especially in cities with high HIV prevalence, must be evaluated. In our view, the available data (albeit not definitive) are strong enough to support the provision of post-exposure prophylaxis in select cases of sexual and injection drug use exposure in addition to occupational exposures. However, post-exposure treatment should be used judiciously and only in the context of a comprehensive prevention program. Ultimately, primary exposure prevention, whether in health care facilities or in the community, is the most important strategy to prevent AIDS.

A randomized clinical trial of mupirocin in the eradication of Staphylococcus aureus nasal carriage in human immunodeficiency virus disease

Seventy-six human immunodeficiency virus (HIV)-infected patients with Staphylococcus aureus nasal carriage were randomized to treatment groups receiving intranasal mupirocin or placebo twice daily for 5 days. Nasal cultures for S. aureus were obtained at 1, 2, 6, and 10 weeks after therapy. At 1 week, 88% of mupirocin-treated patients had negative nasal cultures compared with 8% in placebo patients (P<.001). The percentage of mupirocin-treated patients with persistently negative nasal cultures decreased over time (63%, 45%, and 29% at 2, 6, and 10 weeks, respectively) but remained significantly greater than the placebo group (3% at 2, 6, and 10 weeks). In mupirocin-treated patients, most (16/19) instances of nasal recolonization were with pretreatment strains (determined by means of by pulsed field gel electrophoresis); mupirocin resistance was not observed. Five days of treatment with mupirocin eliminated S. aureus nasal carriage in HIV-infected patients for several weeks; however, since the effect waned over time, intermittent dosing regimens should be considered for long-term eradication.

Penicillin-nonsusceptible Streptococcus pneumoniae at San Francisco General Hospital

Positive pneumococcal cultures of specimens from adult inpatients at San Francisco General Hospital (SFGH) during the period of 11 August 1994 through 31 December 1996 were identified retrospectively. Of the isolates recovered, 15.5% were not penicillin-susceptible (MIC, > or =.1 microg/mL). A case-control study was performed to evaluate risk factors for colonization or infection with penicillin-nonsusceptible Streptococcus pneumoniae (PNSP) and outcomes. Cases (n = 65) were adult inpatients with a positive culture for PNSP, and controls (n = 411) were adult inpatients with a positive culture for penicillin-susceptible pneumococci (PSSP) and no evidence of PNSP. Cases were less likely to have pneumococcal bacteremia (15.4% versus 39.4%; P<.001) and less likely to have pneumonia (50.8% versus 68.9%; P = .006). In a multiple logistic regression model, recent hospital admission and absence of bacteremia were independent predictors of penicillin-nonsusceptibility. Human immunodeficiency virus infection, mortality, and length of hospitalization were not significantly different among cases and controls. These data suggest that PNSP may be less virulent (cause less pulmonary infection) and/or less invasive (cause fewer bloodstream infections) than PSSP at SFGH.

Postexposure prophylaxis for human immunodeficiency virus (HIV) infection following sexual assault

Although the 1998 Centers for Disease Control and Prevention's guidelines for treatment of sexually transmitted diseases recommend offering postexposure prophylaxis for human immunodeficiency virus (HIV) infection following sexual assault, there are no detailed protocols on how to provide this treatment. Postexposure prophylaxis has been shown to lower the risk of seroconversion following occupational exposure to HIV by 81%, but has not yet been evaluated following sexual exposure. Though scientific data are limited, victims of sexual assault should be given the best information available to make an informed decision regarding postexposure prophylaxis. When the choice is made to take medications to prevent HIV infection, treatment should be initiated as soon as possible, but no later than 72 hours following the assault, and should be continued for 28 days. HIV postexposure prophylaxis should be provided in the context of a comprehensive treatment and counseling program that recognizes the physical and psychosocial trauma experienced by victims of sexual assault.

Occupational exposures to body fluids among medical students. A seven-year longitudinal study

BACKGROUND

Medical students may be at high risk for occupational exposures to blood.

OBJECTIVE

To measure the frequency of medical students' exposure to infectious body substances, to identify factors that affect the probability of such exposure, and to suggest targets for the prevention of such exposure.

DESIGN

Review of all exposures reported by medical students at the University of California, San Francisco, School of Medicine.

SETTING

Teaching hospitals affiliated with the University of California, San Francisco.

PARTICIPANTS

Third- and fourth-year medical students from the classes of 1990 through 1996 at the University of California, San Francisco, School of Medicine.

INTERVENTIONS

A needlestick hotline service was instituted at teaching hospitals affiliated with the University of California, San Francisco, and a required course was created to train students in universal precautions and clinical skills before the beginning of the third-year clerkship.

MEASUREMENTS

Reports of exposures made to the needlestick hotline service, including type of exposure, training site, clerkship, and time of year.

RESULTS

119 of 1022 medical students sustained 129 exposures. Of these exposures, 82% occurred on four services: obstetrics-gynecology, surgery, medicine, and emergency medicine. The probability of exposure was not related to graduation year, clerkship location, previous clerkship experience, or training site. Surveys of two graduating classes at the beginning and end of the study showed that the percentage of exposures reported increased from 45% to 65% over the 7-year study period. Thus, the reported injury rates represent minimum estimates of actual occurrences. Human immunodeficiency virus infection and hepatitis were not reported, although follow-up was limited.

CONCLUSIONS

Instruction in universal precautions and clinical procedures is not sufficient to prevent exposures to blood during medical training. Medical schools must assume greater responsibility for ensuring that students are proficient in the safe conduct of clinical procedures and must develop systems that protect students so that they can report and learn from their mistakes.

Incidence and clinical implications of isolation of Mycobacterium kansasii: results of a 5-year, population-based study

BACKGROUND

Mycobacterium kansasii, an unusual pathogen in the pre-AIDS era, is increasingly reported to cause infection among patients with HIV infection. Little is known about the epidemiology and clinical implications of M. kansasii infection in the AIDS era.

OBJECTIVE

To compare the incidence, demographic characteristics, and clinical features of M. kansasii infection in HIV-positive and HIV-negative persons.

DESIGN

Population-based laboratory surveillance.

SETTING

Three counties in northern California.

PATIENTS

All persons who had a positive culture for M. kansasii between 1 January 1992 and 31 December 1996.

MEASUREMENTS

Cumulative incidence rates were calculated for each year by dividing the number of adult patients by the annual estimated adult population. Demographic and socioeconomic data for a single county were obtained by linkage with the 1990 U.S. Census report.

RESULTS

270 patients (69.3% of whom were HIV positive) were identified, for an incidence of 2.4 cases per 100,000 adults per year (95% CI, 2.1 to 2.7), 115 cases per 100,000 HIV-positive persons per year (CI, 99 to 133), and 647 cases per 100,000 persons with AIDS per year (CI, 554 to 751). Indicators of lower socioeconomic status were common among patients: Median incomes were $32,317 in census tracts in which cases were identified and $38,048 in census tracts without cases (P = 0.001), and 35.7% of patients had unstable housing situations. Ninety-four percent of cases were from respiratory isolates, and 87.5% of patients had evidence of infection. Persons with HIV infection differed from those without HIV infection with respect to mycobacteremia (9.6% compared with 0%; P = 0.001), need for hospitalization (77.4% compared with 51.9%; P < 0.001), and smear positivity (41.7% compared with 20.7%; P = 0.005). Chronic diseases were common among HIV-negative persons; however, 40.3% had no predisposing medical condition.

CONCLUSIONS

Mycobacterium kansasii isolation is more common in HIV-positive persons, but most patients with M. kansasii infection have clinical and radiologic evidence of infection regardless of HIV status. Persons infected with HIV and M. kansasii have a higher rate of hospitalization and a greater burden of organisms. A possible association with poverty suggests mechanisms of transmission and requires further study.

Understanding, predicting and controlling the emergence of drug-resistant tuberculosis: a theoretical framework

The high prevalence of tuberculosis in developing countries and the recent resurgence of tuberculosis in many developed countries suggests that current control strategies are suboptimal. The increase in drug-resistant cases exacerbates the control problems. Currently employed epidemic control strategies are not devised on the basis of a theoretical understanding of the transmission dynamics of Mycobacterium tuberculosis. We describe and discuss a theoretical framework based upon mathematical transmission models that can be used for understanding, predicting, and controlling tuberculosis epidemics. We illustrate how the theoretical framework can be used to predict the temporal dynamics of the emergence of drug resistance, to predict the epidemiological consequences of epidemic control strategies in developing and developed countries, and to design epidemic control strategies.

Nosocomial transmission of opportunistic infections

Immunocompromised patients are at high risk for opportunistic infections. Traditionally, these infections were thought to arise from endogenous reactivation of previously acquired latent infections, and nosocomial transmission therefore was deemed to be so unlikely that no special infection control interventions were needed to prevent transmission in healthcare settings. However, new data have challenged this view and suggest that some opportunistic pathogens are transmissible from one immunosuppressed patient to another. Epidemiological investigations, molecular genotyping, animal studies, and air-sampling experiments lend support to the hypothesis that reinfection with opportunistic pathogens does occur, that airborne transmission is possible, and that nosocomial spread is a plausible explanation for case clusters. Taken together, these observations support the view that some opportunistic infections are exogenous in origin and that additional epidemiological investigations are needed to define the true risk of nosocomial spread and need for isolation.

The care of persons with recent sexual exposure to HIV

Until recently, patients had little motivation to seek medical care soon after sexual exposure to HIV. However, evidence that antiretroviral treatment prevents HIV infection after occupational exposure has led to the recommendation that prophylaxis be considered after sexual exposure. This recommendation will result in an increased number of recently exposed patients presenting for care. Clinicians should seize this opportunity to reach persons who are at high risk for HIV seroconversion and provide them with evaluation, treatment, and counseling. A comprehensive approach to the care of persons recently exposed to HIV is proposed. Candidates for postexposure prophylaxis should be identified and given appropriate antiretroviral treatment. Physicians must perform HIV antibody testing to determine which persons are already infected with HIV and must do baseline laboratory studies. Follow-up care includes assessment of side effects from postexposure treatment and surveillance for development of primary HIV infection. Most important, clinicians must provide risk-reduction counseling to decrease the chance of future exposures. Public health messages must emphasize that postexposure treatment should be used only as a backup for failure of primary prevention methods, such as avoidance of high-risk sexual exposures or use of condoms.

Accidental exposures to blood and body fluids among health care workers in dental teaching clinics: a prospective study

The authors evaluated accidental exposures to blood and body fluids reported to a hotline or to health officials at four dental teaching clinics. The authors used a standard questionnaire to solicit and record data regarding each exposure. During a 63-month period, 428 parenteral exposures to blood or body fluids were documented. Dental students and dental assistants had the highest rates of exposure. Syringe needle injuries were the most common type of exposure, while giving injections, cleaning instruments after procedures and drilling were the activities most frequently associated with exposures.

Prophylaxis for occupational exposure to HIV

Effective prophylaxis for infection with the human immunodeficiency virus (HIV) is important for health care providers at risk for exposure to infected blood. The average risk from percutaneous exposure is approximately 0.3%, but exposures involving a high titer of HIV or a large volume of infections material are apt to be much riskier. A convergence of indirect evidence strongly suggests that chemoprophylaxis with zidovudine after exposure to HIV may be efficacious. Treatment with zidovudine after percutaneous exposure appears to reduce the odds of infection by almost 80%. Zidovudine prophylaxis effectively prevents perinatal HIV transmission, and treatment during acute retroviral infection may attenuate HIV disease. Reports of "aborted" HIV infection among health care providers who have been stuck with contaminated needles suggest that antiretroviral treatment in the window of opportunity after exposure to HIV could prevent virus propagation and allow local cutaneous host defenses to clear the infection. Although efficacy has not been shown in controlled clinical trials, these data support a potential benefit from treatment after exposure. It is difficult to define the optimal regiment that should be used for prophyaxis, given the emergence of antiretroviral resistance among source patients. Current recommendations favor the use of zidovudine plus lamivudine for 4 weeks. Use of indinavir or other protease inhibitors is advised when the source patient is likely to harbor resistant virus or when exposure is especially hazardous.

Are universal precautions realistic?

In concluding whether universal precautions are necessary, it certainly appears that we need something to reduce the significant problem of HIV transmission to health-care providers. As occupational risk goes, it exceeds the occupational risk of a number of other high-risk professions. Unfortunately, we do not know if universal precautions are effective. We also do not know the true compliance rate in use of universal precautions, nor whether they have an impact on transmission even if effectively used. What are the alternatives? They are not great, but some have not been adequately explored or implemented. Re-engineering around needle use in the hospital is clearly the most likely area to produce concrete results, because needlesticks are overwhelmingly the greatest source of infection, but this has not been encouraged to the degree it could be, even with systems already developed. Universal testing does not appear to be a viable alternative, for numerous reasons already discussed. Finally, are universal precautions more important for other pathogens than HIV? I would say yes. Hepatitis B, hepatitis C, and nosocomial infections are more important both as public health issues and as health-care provider prevention issues. If universal precautions are effective in reducing any of these, they are worthwhile.

Hand protection

The traditional purpose of surgical gloves is to prevent transmission of pathogens (usually bacterial) from surgeon to patient. Yet the hand is also the most common site of injury and blood contamination among operating room personnel. Thus, gloves also can protect against transmission of pathogens from patient to surgeon. This article focuses on the value of gloves for hand protection. The current data on such protection derive exclusively from studies that use glove leak and contamination as outcome measures. There are no data that measure protection in terms of actual disease transmission.

Effect of testing method on apparent activities of antiviral disinfectants and antiseptics

This study was designed to evaluate the independent effects of various test methods on the activities of antiviral chemical germicides. The activities of germicides against MS2 and phi 6 bacteriophages in a new porcine tissue carrier model were compared to those obtained by four other methods (suspension, glass carrier, tile carrier, and fingerpad tissue carrier tests). After a 1-min contact followed by neutralization (and elution off the carriers), the residual virus in the treated samples was quantified and the amount was compared with that in the saline controls. Antiviral activity was highly dependent on the test method for both viruses and was always greatest in suspension tests and lowest in tissue carrier tests. Results obtained for hydrophilic MS2 with the porcine tissue carrier were comparable to those from fingerpads, but lipophilic phi 6 was subject to spontaneous inactivation on human skin and proved unsuitable for fingerpad testing. These data indicate that the activities of germicides in tests with nonbiological substrates may overestimate antiviral antiseptic activity on skin surfaces. Products intended for use as antiviral antiseptics or hand-washing agents should be evaluated in a tissue carrier system. The porcine tissue carrier model provides a safe, inexpensive, accurate, and reproducible method for testing the activities of antiseptics.

Incidence and prevalence of human immunodeficiency virus, hepatitis B virus, hepatitis C virus, and cytomegalovirus among health care personnel at risk for blood exposure: final report from a longitudinal study

In a 10-year dynamic cohort study, 976 health care providers were followed a mean of 1.9 years to evaluate the risk of human immunodeficiency virus (HIV) transmission, delayed seroconversion, and seronegative latent infection following occupational exposures. The seroprevalence and incidence of HIV, hepatitis B virus (HBV), hepatitis C virus (HCV), and cytomegalovirus (CMV) infection were also measured, with annual serologic testing for viruses and postexposure HIV tests. One of 327 percutaneous exposures (0.31%; confidence interval, 0.008%-1.69%) and 0 of 398 mucocutaneous exposures to HIV-infected blood transmitted HIV. Neither delayed seroconversions nor seronegative latent infections were detected. The baseline seroprevalences of HBV, HIV, HCV, and CMV infection were 21.7%, 0, 1.4%, and 43.4%, respectively. Corresponding incidence density rates were 3.05, 0.055, 0.08, and 2.48 (per 100 person-years). Despite infection control precautions and availability of hepatitis B vaccine, these health care providers remain at risk for acquiring bloodborne viral infections.

Efficacy of gloves in reducing blood volumes transferred during simulated needlestick injury

This study was designed to evaluate factors that affect blood volumes transferred to skin during simulated needlestick injuries in an in vitro paper prefilter model and an ex vivo porcine tissue model. The effect of needle type and size, penetration depth, and glove use on the volume of radiolabeled blood transferred was determined in each model. Blood volumes ranged from 0.47 +/- 0.26 microL (30-gauge needle, 0.5-cm depth, in vitro model) to 5.88 +/- 1.45 microL (18-gauge needle, 2.0-cm depth, in vitro model). Needle size and penetration depth were significantly associated with transfer volume. Glove material reduced the transferred blood volume by 46%-86% in both models. Transfer volumes were within the same order of magnitude for all conditions. Hence, virus titer in the source blood may be a better predictor of needlestick infectivity than is exposure volume. Regardless, gloves may exert some protective effect and should be worn whenever needles are handled.

Procedure-specific infection control for preventing intraoperative blood exposures

Contemporary intraoperative infection control must address the risk of infection transmission to both patients and their providers. The patient must be protected from intraoperative wound contamination and exposure to blood-borne pathogens during procedures. Providers must be protected from injuries and mucocutaneous exposure to the patient's blood. Procedure-specific infection control precautions, or similar strategies that address this bidirectional potential for infection transmission, may prove successful in accomplishing improved safety for all.

Management of occupational exposures to bloodborne pathogens: hepatitis B virus, hepatitis C virus, and human immunodeficiency virus

Being a health care worker in today's world is not without risks. Accidental exposure to blood carries with it a definite risk of transmission of infection by various bloodborne pathogens, especially the hepatitis B, hepatitis C, and human immunodeficiency viruses. While infectious disease specialists, hospital epidemiologists, and infection control clinicians can develop many important strategies to reduce this risk--aggressive training, utilization of safer needles, identification of high-risk activities, and efficient disposal systems--their overriding responsibility is to design and implement a comprehensive plan for expeditiously and effectively dealing with accidental exposures when they occur. Among other things, the plan must address a number of key issues, including testing, administering postexposure prophylaxis, providing short- and long-term follow-up care, and, particularly, counseling for helping the health care worker deal with the tremendous anxiety associated with the injury. Drs. Julie L. Gerberding of the University of California, San Francisco, and San Francisco General Hospital and David K. Henderson of the National Institutes of Health and the Warren G. Magnuson Clinical Center have both made significant contributions in this area; in this month's AIDS Commentary they discuss the essential elements of such a plan.

Comparison of conventional susceptibility tests with direct detection of penicillin-binding protein 2a in borderline oxacillin-resistant strains of Staphylococcus aureus

Six selected strains of Staphylococcus aureus classified as borderline oxacillin-resistant, according to standard disk diffusion and microdilution susceptibility test methods, and seven methicillin-resistant and seven methicillin-susceptible control strains were examined for the presence of penicillin-binding protein 2a (PBP 2a) by fluorography and immunoblotting and for DNA hybridization with a mec-specific probe in a dot blot assay. Oxacillin agar screen tests with and without NaCl supplementation were also performed with all strains. PBP 2a was detected both by fluorography and by immunoblotting in all seven methicillin-resistant control strains and in none of the susceptible controls. PBP 2a was detected in two borderline strains. Results of agar screen tests performed without NaCl supplementation were completely concordant with susceptibility determined by PBP 2a and mec detection methods. Agar screening with NaCl supplementation was less accurate. These findings were confirmed with 20 additional borderline strains. Direct detection methods for the presence of PBP 2a or mec, the gene encoding it, allow accurate and definitive classification of borderline strains. Further efforts to develop a rapid, clinically useful, antibody detection system for PBP 2a are warranted.

AIDS risk and risk reduction in the radiology department

As the AIDS epidemic progresses, concern about the risk of occupational transmission of the causative organism, human immunodeficiency virus (HIV), is increasing. In this article, we summarize the risk of occupational acquisition of HIV in the health care setting and specify protocol and equipment that can reduce this risk in the radiology department. Accidental needle-stick injury is the most common form of exposure to infected blood, which is the only body fluid implicated to date in the occupational transmission of HIV. Prospective cohort studies demonstrate a 0.3-0.4% risk of infection for each needle-stick event. The most important instruction to health care workers that can reduce this risk is the following: Do not recap needles. Other risk-reduction measures include the adoption of universal precautions against transmission of infectious disease; sharp-instrument precautions; the use of protective garb to prevent skin and mucous membrane contamination when blood or bloody body fluid may splash; the availability of stable, puncture-resistant disposal containers for sharp instruments; the exclusion of breakable glass syringes; and the accessibility of resuscitation equipment in all rooms in order to avoid direct mouth-to-mouth contact. These and other measures discussed here are designed to prevent exposure of skin or mucous membrane to blood. If exposure does occur, the contaminated area should be washed immediately. A multicenter research protocol to evaluate the effectiveness of zidovudine (AZT) therapy in preventing seroconversion after exposure to HIV-contaminated blood recommends AZT therapy after massive exposure (e.g., injection of measurable quantities of blood) and endorses it for serious parenteral exposure (e.g., deep needle sticks).

Does knowledge of human immunodeficiency virus infection decrease the frequency of occupational exposure to blood?

Implementation of universal precautions is advocated to prevent exposure to human immunodeficiency virus (HIV) and other bloodborne pathogens. Critics of this approach argue that additional benefit can be derived by identifying and labeling patients known to be infected. Knowledge of HIV infection status could result in a reduced exposure rate by two mechanisms: (a) by motivating improved compliance with universal precautions, or (b) by allowing changes in procedure or technique not feasible for all patients. Compliance with universal precautions may reduce the frequency of some types of exposure but has not been associated with a reduction in the frequency of needlestick exposures in several studies. Despite the perception by some health care workers that awareness of HIV status will result in improved safety, no objective data have demonstrated a direct benefit from testing or identifying infected patients. Health care workers who recognize the presence of occupational HIV risk are apt to be motivated to practice universal infection control precautions and experience little additional benefit from testing individual patients. Health care workers in low prevalence areas may experience less incentive to comply routinely with universal precautions and selectively may be motivated when HIV infection is diagnosed in individual patients. However, routine testing in areas of low HIV prevalence is not likely to be cost effective. Until further research clarifies the efficacy and costs of universal precautions or HIV testing, infection control standards should maximize local autonomy in developing rational policies consistent with institutional needs.

Transmission of HIV in health care workers

Health care workers may be occupationally exposed to human immunodeficiency virus (HIV). The risk of infection is highest with accidental needlestick and similar percutaneous exposures. Emphasis should be placed on avoiding this type of accident. Strategies to prevent accidents and to manage exposures once they have occurred should be developed in each work environment. It is to be hoped that a combination of better infection control, safer devices and technologies, and postexposure prophylaxis with zidovudine (AZT) or other chemotherapeutic agents will help prevent infection in health care providers caring for HIV-infected patients.

Reducing occupational risk of HIV infection

At San Francisco General Hospital and many other institutions in areas of high HIV prevalence, a policy of body substance isolation has proved easier to implement than the CDC's across-the-board recommendations. Prevention of needle-stick injury and use of barrier methods of infection control are emphasized. Preoperative HIV testing is addressed.