Journal Reviews

Nuortis JP, Butler JC, Crutcher JM, et al. An outbreak of multidrug-resistant pneumococcal pneumonia and bacteremia among unvaccinated nursing home residents. N Engl J Med 1998; 338: 1,861-1,868.

Clusters of pneumococcal disease may be under-recognized in nursing homes, and wider use of pneumococcal vaccine is important to prevent institutional outbreaks of drug-resistant Streptococcus pneumoniae infection, the authors report. They investigated an outbreak of multidrug-resistant pneumococcal pneumonia among the residents of a nursing home in rural Oklahoma. Only 4% of the residents had been vaccinated.

Pneumonia developed in 11 of 84 residents (13%), three of whom died. Multidrug-resistant S. pneumoniae, serotype 23F, was isolated from blood and sputum from seven of the 11 residents with pneumonia (64%), and from nasopharyngeal specimens from 17 of the 74 residents tested (23%) and two of the 69 employees tested (3%). Recent use of antibiotics was associated with both colonization and disease. After residents received pneumococcal vaccine and prophylactic antibiotics, there were no additional cases of pneumonia, and the rates of carriage decreased substantially.

Although the dynamics of S. pneumoniae colonization among institutionalized populations have not been well-described, transmission from hospital staff to patients has been suggested. Exactly how and when the epidemic strain was introduced into the nursing home we studied is unknown, but two findings suggest person-to-person transmission from staff members to residents, the authors report.

"First, the patients with pneumonia and the carriers were randomly distributed in the facility, so there was no pattern of transmission from colonized roommates," they found. "Second, contact with colonized nursing staff was the only potential source of exposure for two bedridden patients, who were not exposed to other residents or visitors."

In view of the lack of effective means to reduce or prevent transmission, the possible increase in pneumococcal outbreaks, and the continuing emergence of drug resistance, nursing homes should offer pneumococcal vaccine to all eligible residents and to new residents on admission to the facility, they emphasize.

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Muscher DM. Editorial: Pneumococcal outbreaks in nursing homes. N Engl J Med 1998; 338:1,915-1,916.

Inertia among health care providers is the principal reason for the underuse of a reasonably effective and benign pneumococcal vaccine. But an increasingly informed American public will ultimately provide the impetus to increase compliance with recommendations, notes the author of an editorial accompanying the above report.

"Our profession has traditionally been slow to adopt vaccination of adults for reasons that include inertia, the principle of primum non nocere (first, do no harm), and fear of litigation," he reports. ". . . [But] vaccination is benign. Many studies show that it reduces the rate of pneumococcal disease by about two-thirds. Physicians ought to use this vaccine more liberally."

Some studies suggest that the vaccine may not effectively reduce the rate of pneumococcal pneumonia in elderly populations. In contrast, many other studies using a variety of statistical approaches have documented an efficacy rate of 60% to 70%. Addressing another concern, the author emphasizes that there is no reason to believe that vaccination will lead to an increase in pneumococcal disease caused by strains that were not included in the vaccine.

Another compelling reason to immunize is that some 25% of all pneumococcal isolates from normally sterile sites now have reduced susceptibility to penicillin.

"Increasingly, the American public will demand the pneumococcal vaccine," he states. "The lay press has given sufficient attention to bacterial infections and antibiotic resistance to alarm nearly everyone, and it does not take long to realize that vaccination is one of the few steps one can take to protect oneself and one's family. And requests from our patients might remind us of the need for this vaccine among elderly persons in institutions, who may not be able to ask for it for themselves."

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Huycke MM, Sahm DF, Gilmore MS, et al. Multiple-drug resistant enterococci: The nature of the problem and an agenda for the future. Emerg Infect Dis 1998; 4:239-246.

The Centers for Disease Control and Prevention's Hospital Infection Control Practices Advisory Committee has strongly recommended restricting oral and parenteral vancomycin to control vancomycin-resistant enterococci. However, limiting use of vancomycin while ignoring widespread use of other broad-spectrum antibiotics likely will not lead to maximum control of VRE or other multidrug-resistant (MDR) enterococci, the authors point out.

Antibiotics may promote colonization and infection with MDR enterococci by at least two mechanisms, they explain. First, many broad-spectrum antibiotics have little or no anti-enterococcal activity, and administration commonly leads to overgrowth of susceptible (or resistant) enterococci at sites at risk for infection. Second, most antibiotics substantially reduce the normal resistance of the intestinal tract to colonization by exogenous organisms.

Colonization resistance results primarily from the "limiting action" of the normal anaerobic flora, and to a lesser extend from an intact mucosa, gastric acid secretion, intestinal motility, and intestinal-associated immunity. Antibiotic-induced alterations in the protective flora of the intestine provide large footholds for colonization with exogenous pathogens such as MDR enterococci.

"Antibiotic restriction programs would be more effective if they included prudent prescribing of all antibiotics, not just single agents such as vancomycin," the authors note, citing a study in which that approach substantially decreased intestinal colonization with VRE by restricting use of vancomycin, cefotaxime, and clindamycin.

At a minimum, a successful program for control of MDR enterococci requires effective passive and active surveillance to identify colonized and infected patients, absolute adherence to contact isolation by health care workers, rigorous decontamination of patient-contact areas, and judicious use or restriction of vancomycin and other broad-spectrum antibiotics, they conclude.

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Mendelson MH, Short LJ, Schechter CB, et al. Study of a needleless intermittent intravenous-access system for peripheral infusions: Analysis of staff, patient, and institutional outcomes. Infect Control Hosp Epidemiol 1998; 19:401-406.

A needleless intermittent intravenous access system with a reflux valve for peripheral infusions was effective in reducing percutaneous injuries to staff and was not associated with an increase in either insertion-site complications or nosocomial bacteremia, the authors report.

They conducted a six-month cross-over clinical trial of a needleless intermittent intravenous access system (NL; study device) compared to a conventional heparin-lock system (CHL; control device). The study included 594 patients during 602 patient admissions, comprising a random sample of all patients with a study or control device inserted within a previous 24-hour period on study and control units.

During the study, 35 percutaneous injuries were reported. Eight injuries were CHL-related; no NL-related injuries were reported. Of 773 episodes of positive blood cultures on study and control units, 6 (0.8%) were device-related, with no difference between NL and CHL. Of nursing staff responding to a product evaluation survey, 95.2% preferred the study over control device.

The projected annual incremental cost of implementation for the hospital was $82,822, or $230 per 1,000 patient days. The incremental cost per exposure prevented was estimated at $1,593.

"Although the number of injuries related to the standard device reported during the study period was higher than in the previous period, perhaps due to increased motivation by staff, it is likely that reporting still was not complete and that a greater number of injuries actually would have been prevented," they concluded.