Literature Reviews
Adal KA, Flowers RH, Anglim AM, et al. Prevention of nosocomial influenza. Infect Control Hosp Epidemiol 1996; 17:641-648.
Researchers at the University of Virginia Hospital in Charlottesville studied compliance with preventive strategies during a nosocomial influenza A outbreak in 1988, as well as rates of vaccination of health care workers and of nosocomial influenza following changes in vaccine practices after the outbreak.
The authors emphasize the need for staff influenza vaccination and amantadine prophylaxis to prevent morbidity, absenteeism, and transmission to patients. Despite the importance of these considerations, vaccination rates among HCWs have remained low. Acceptance of routine amantadine prophylaxis by medical personnel has not been documented, they point out.
During the 1988 outbreak, exposed HCWs were identified by infection control practitioners and reported to the employee health department, which contacted them for evaluation. Unvaccinated HCWs with exposure within the previous 72 hours to unisolated cases of influenza were offered vaccine and 14 days of amantadine hydrochloride prophylaxis. Employees with exposure more than 72 hours before evaluation were offered vaccine. Exposed workers with influenza symptoms were offered amantadine. Those refusing vaccine or amantadine were asked why.
Vaccine had been offered free in the employee health department for more than 10 years prior to the outbreak, after which a new method of administration was initiated involving vaccination on hospital units from a mobile cart.
Between Jan. 23 and April 2, 1988, 31 patients were admitted to the hospital with community-acquired influenza; 10 patients were identified as having nosocomial influenza. During the outbreak, 171 HCWs had direct exposure to unisolated patients with influenza. Only seven (4%) of those exposed workers had been vaccinated during the previous fall. Thirty-five of the 171 could not be contacted for evaluation. Twenty-four were evaluated more than 72 hours postexposure, and three of those took the vaccine. Of 105 previously unvaccinated HCWs exposed within 72 hours, 15 (14.3%) agreed to take amantadine, six (5.7%) agreed to take vaccine, and only three (2.9%) took both vaccine and amantadine, as recommended by the federal Centers for Disease Control and Prevention.
Reasons most commonly given for refusal during the outbreak were doubts about efficacy, concerns about side effects, and unfamiliarity with amantadine.
Frequency of HCW vaccinations given by the employee health department could not be determined prior to the winter of 1989-1990 due to record-keeping methods. However, vaccination rates among HCWs increased from 26.3% in 1989-1990 to 38.3% in 1993-1994. Frequency of laboratory-confirmed influenza among employees decreased significantly.
"The extremely low vaccine compliance rates documented during the 1988 epidemic suggested that a policy of merely offering the vaccine free of charge to employees was unlikely to prevent the spread of nosocomial influenza," the authors state. "Mobile-cart vaccination on hospital wards was instituted later that year, and vaccination rates increased significantly in subsequent years with this strategy, but still have remained well below the ideal."
Much higher proportions of HCWs need to be immunized to further reduce nosocomial influenza. The authors cite strategies such as computer-generated reminders, education to dispel erroneous beliefs about side effects, expanding vaccine availability to night and weekend workers, requiring reluctant employees to sign informed refusal forms, awarding vacation days or preferential schedules to compliant HCWs, and making the vaccine mandatory. They also suggest informing workers that vaccination represents a national health care policy.
Acceptance of amantadine prophylaxis is affected by the drug’s "forbidding" list of side effects (including hallucinations, anorexia, nausea, and ataxia), which occur in up to 33% of patients. Rimantadine also is effective chemoprophylaxis and has less central nervous system toxicity. However, the difference in cost between the two antivirals could present a problem for employee health departments. A 100 mg capsule of generic amantadine costs $.30, whereas the same amount of rimantadine costs $1.19. t
Glatt AE. Proposed antiretroviral therapy guidelines for prophylaxis of occupationally related HIV seroconversion: A practical approach. Infect Control Hosp Epidemiol 1996; 17:672-674.
This article by the chief of infectious diseases and infection control committee chairman at Catholic Medical Center (CMC) of Brooklyn and Queens in Jamaica, NY, presents principles on which guidelines for aggressive treatment of health care workers occupationally exposed to HIV were based. The report is followed by a comment from the federal Centers for Disease Control and Prevention. (See next review item, p. 11.)
Glatt outlines the seven basic principles of his facility’s occupational HIV exposure treatment protocol, which was developed in December 1995:
1. Viral load in the index patient affects seroconversion likelihood.
2. Deep or penetrating injuries, especially from hollow needles or visibly contaminated devices, or injuries from procedures involving direct placement into an artery or vein, increase seroconversion risk.
3. Different HIV strains may carry different seroconversion likelihoods.
4. Known or potential HIV resistance alters prophylactic therapy efficacy.
5. Triple-combination antiretroviral therapy generally is superior to monotherapy or double-combination therapy for HIV treatment and for reducing viral load.
6. Zidovudine (AZT, Retrovir) prophylaxis reduces seroconversion risk.
7. Viral replication in a new host is a rapid, dynamic, continuously evolving process.
CMC’s protocol is similar to the U.S. Public Health Service’s (PHS) recently released provisional recommendations for chemoprophylaxis after occupational HIV exposure (see related story in Hospital Employee Health, August 1996, pp. 85-92), with several minor differences.
The protocol states that CMC employees who incur a needlestick or mucous membrane exposure from a known or potentially HIV-infected source should be evaluated and considered for the following interventions:
• HCWs should be evaluated immediately either in the employee health service or the emergency department (or by the most readily accessible knowledgeable physician, if neither is available).
• After local wound cleansing and care, general medical evaluation, and HIV screening and counseling, HCWs deemed at risk of occupational HIV seroconversion should be recommended for antiretroviral prophylaxis as soon as possible postexposure.
While PHS guidelines "recommend" therapy for workers at highest risk and only "offer" treatment to those with lower-risk exposures reserving triple-drug therapy for those at higher risk and suggesting single-agent or double therapy for the remainder CMC recommends triple therapy for any exposure deemed capable of transmitting HIV. Glatt defines such exposures as all that are not negligible.
"It is very difficult as a practical matter to distinguish among risk exposures, and even if possible, drug resistance still may be present. Finally, why should a health care worker not be recommended optimal therapy’ just because his risk is fortunately lower," Glatt states.
His preferred prophylaxis regimen is triple-drug combination therapy for four weeks (with dosing adjusted as necessary for renal or hepatic impairment):
• AZT 200 mg PO three to five times per day. Glatt notes that PHS guidelines recommend tid therapy (the standard treatment dose, especially when used with lamivudine), but many patients in the CDC’s December 1995 MMWR report were treated with a 1,000 mg/day regimen;
• lamivudine (3TC, Epivir) 150 mg PO bid;
• a protease inhibitor, either indinavir (Crixivan) 800 mg tid, ritonavir (Norvir) 600 mg PO bid, or saquinavir (Invirase) 600 mg PO tid. PHS guidelines recommend indinavir as first choice, followed by saquinavir. Ritonavir is not recommended at all, probably due to potential drug interactions, Glatt surmises, but "indinavir is not readily available, and ritonavir is a very potent agent, especially useful for patients not taking other medications." CMC guidelines allow the most potent available protease inhibitor to be used.
AZT alone is offered to employees who prefer to take only one drug. If two medications are preferred, AZT and 3TC are used. Informed consent is obtained, regardless of the therapy.
Glatt notes that the CMC recommendations are merely suggestions, not mandatory or absolute guidelines. All affected employees are referred to a private doctor or to the employee health service for follow-up. t
Bell DM. Comment from the CDC. Infect Control Hosp Epidemiol 1996; 17:674.
Responding to the article reviewed above, the chief of the federal Centers for Disease Control and Prevention’s HIV infections branch explains the U.S. Public Health Service’s rationale for not recommending that the new antiretroviral drugs be used routinely to treat lower-risk exposures.
First, limited data are available on the safety and tolerability of the newer drugs. Also, "the overwhelming majority of workers with lower-risk exposures will not become infected," says Bell, who notes that the average risk of HIV transmission is 0.3% after a percutaneous exposure to HIV-infected blood and less than that for a mucous membrane or skin exposure.
He also explains that the PHS currently considers indinavir the most appropriate protease inhibitor for postexposure prophylaxis "based on considerations of antiretroviral activity, bioavailability, safety and tolerability as initial therapy, and number of drug interactions."
Ritonavir was not recommended, mainly due to frequent gastrointestinal symptoms at treatment onset when combined with zidovudine. Dose escalation regimens to reduce these symptoms are probably inappropriate for postexposure prophylaxis, where rapid initiation of therapy is important, Bell advises. He further suggests that indinavir can be ordered and available for immediate use by calling Merck & Co. at (800) 637-2579.
Because limited information on safety and tolerability of antiretroviral agents as postexposure prophylaxis impedes development of recommendations, Bell asks health care providers to enroll prospectively all HCWs who receive HIV postexposure prophylaxis in a registry with no personal identifiers. The number is (888) 737-4448.
Violence in the Workplace: Risk Factors and Prevention Strategies is a National Institute for Occupational Safety and Health (NIOSH) report that identifies factors associated with the risk of workplace violence, examines injury rates and deaths by industry and occupation, and suggests practical strategies. The report notes that health care workers are at greatest risk of nonfatal assaults. Copies of the document Current Intelligence Bulletin 57, DHHS NIOSH Publication No. 96-100 are available from NIOSH Publica tions Dissemination, 4676 Columbia Parkway, Cincinnati, OH 45226-1998. Telephone (800) 35-NIOSH. Fax: (513) 533-8573. It also is available on NIOSH’s World Wide Web home page at http:// www.cdc.gov/niosh/homepage.html.
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