Journal Reviews

False positives found when skin-testing workers

Researchers cite problems with TST reagent

Blumberg HM, White N, Parrott P, et al. False-positive tuberculin skin test results among health care workers. Research letters. JAMA 2000; 283:279.

The authors report false-positive tuberculin skin test (TST) results associated with one of two commercially available reagents, concluding that when a TST is used among a low-risk population — such as health care workers in an institution that has a well-functioning tuberculosis infection control program — the majority of positive results actually may be false.

Two different commercial tuberculin reagents are available in the United States: Aplisol (Parkdale Pharmaceuticals, Rochester, MI) and Tubersol (Pasteur Mérieux Connaught USA, Swiftwater, PA). The authors cite a previous study that concluded that either product will correctly classify comparable numbers of people not infected with TB and "the choice of product used for [tuberculin] skin testing has little effect on test performance." The authors of the current paper note, however, that "experience at our institution with false-positive tuberculin skin test (TST) results among a group of health care workers, which was associated with the use of Aplisol, contradicts these conclusions."

They investigated a marked increase in TST conversions among health care workers at the Grady Health System in Atlanta that began in mid-September 1999. Tuberculin skin tests are mandatory for all health care workers every six months unless there is documentation of a previously positive result. Tests are placed and read by the hospital’s employee health service using the Mantoux method; self-reading is not permitted. Two-step testing is required for newly hired employees. A positive TST is defined as induration of 10 mm or greater.

They found that in the three six-month periods before September 1999, baseline conversion rates were as follows: four (0.09%) of 4,670 health care workers tested between January and June 1998; eight (0.2%) of 4,363 tested from July through December 1998; and five (0.1%) of 4,358 tested from January through June 1999. Between Sept. 15 and Oct. 15, 1999, 11 (1.2%) health care workers had a new TST conversion (median, 12 mm induration; range, 10-20 mm) among 914 individuals tested, a marked increase compared with the previous 1.5 years.

"All 11 health care workers were subsequently found to have chest radiographs that showed no evidence of tuberculosis," the authors noted. "Our investigation found that the pharmacy had switched from Tubersol, which had been used exclusively for the prior six years, to Aplisol because of lower price. . . . All 11 health care workers who tested positive with Aplisol were retested with Tubersol PPD and had a negative TST."


Hospitals lagging in drug resistance efforts

Prescription for prevention going unfilled

Lawton RM, Fridin SK, Gaynes RP, et al. Practices to improve antimicrobial use at 47 U.S. hospitals: The status of the 1997 SHEA/IDSA position paper recommendations. Infect Control Hosp Epidemiol 2000; 21:256-259.

The hue and cry over emerging antibiotic resistance in recent years has stirred control efforts in hospitals, but not nearly to the level experts advise is needed to meet the problem, the authors report.

Of 47 hospitals surveyed, 30% did not have clinical practice guidelines in place to address the issue, and less than half of the hospitals had a system to measure compliance with consultations on initial antimicrobial choice. "Despite recent evidence that selected restrictions decrease antimicrobial resistance, only 40% of hospitals restricted any antimicrobials," the authors found. "It is evident that, in most hospitals surveyed, practices to improve antimicrobial use existed. However, these efforts should be considered a first step in approaching more comprehensive programs."

In most hospitals surveyed, practices to improve antimicrobial use, although present, were inadequate based on joint recommendations by the Society for Healthcare Epidemiology of America and Infectious Disease Society of America, they concluded. IDSA and SHEA recommendations call for hospitals to establish a system for monitoring bacterial resistance and antibiotic usage; establish practice guidelines and other institutional policies to control the use of antibiotics; and respond to data from the monitoring system. Many hospitals employ programs to improve antimicrobial use, which may include restrictions on specific agents, automatic stop orders, clinical practice guidelines (CPGs), and multidisciplinary teams.

To determine the status of programs designed to improve antimicrobial prescribing, the researchers conducted a cross-sectional survey of pharmacy and infection control staff at 47 hospitals participating in phase three of the Intensive Care Antimicrobial Resistance Epidemiology project. All 47 hospitals had some programs to improve antimicrobial use, but the practices reported varied considerably. All used a formulary, and 43 (91%) used it in conjunction with at least one of the other three antimicrobial-use policies evaluated: stop orders, restriction, and CPGs. CPGs were reported most commonly (70%), followed by stop orders (60%) and restriction policies (40%). Although consultation with an infectious disease physician (70%) or pharmacist (66%) was commonly used to influence initial antimicrobial choice, few (40%) reported a system to measure compliance with these consultations.


C. diff.

strikes first-time rehabilitation patients

Nosocomial infections in stroke victims

Mylotte JM, Graham R, Kahler L, et al. Epidemiology of nosocomial infection and resistant organisms in patients admitted for the first time to an acute rehabilitation unit. Clin Infect Dis 2000; 30:425-432

Addressing the need for data on nosocomial infections among patients admitted for acute rehabilitation after stabilization of an acute medical or neurological event (i.e., acute brain injury, stroke), the authors report a new finding that Clostridium difficile diarrhea represented about 15% of the nosocomial infections identified.

"This infection has not been previously identified as a problem in this population," they report. "Nevertheless, it is not surprising that C. difficile diarrhea occurs frequently in the population, given their background of prolonged acute hospital stay and high frequency of antibiotic use both before and during their stay in the rehabilitation unit."

The study also verified that urinary tract and skin/soft-tissue/wound infections were the most common nosocomial infections occurring among patients admitted for acute rehabilitation. The researchers looked for nosocomial bacterial colonization and infection among a cohort of 423 patients admitted to an acute rehabilitation unit. Overall, methicillin-resistant Staphylococcus aureus (MRSA) and enterococci were the most commonly identified colonizing organisms. Escherichia coli and Pseudomonas aeruginosa were the most commonly identified colonizing gram-negative bacilli. During 70 (16.5%) of the 423 hospitalizations in the unit, 94 nosocomial infections occurred. The most common infections were those of the urinary tract (30% of 94 infections) or a surgical site (17%), C. difficile diarrhea (15%), and bloodstream infection (12.8%). Antibiotic-resistant bacteria most commonly caused bloodstream infection (41.7%) and surgical site infection (56.3%). Independent predictors of nosocomial infection at the time of admission were functional status (measured with the functional independence measure), APACHE III score, and spinal cord injury.

The authors also noted an interesting finding that infection control surveillance at the hospital revealed that the largest reservoir of patients with antibiotic-resistant organisms (e.g., MRSA, vancomycin-resistant enterococci, and resistant gram-negative bacilli) was in the acute inpatient rehabilitation unit. "Acute severity of illness may be an important predictor of the development of nosocomial infection among patients admitted for the first time to an acute rehabilitation unit," they concluded.


Safety climate suits health workers well

Perception of management commitment key

Gershon RRM, Karkashian CD, Grosch JW, et al. Hospital safety climate and its relationship with safe work practices and workplace exposure incidents. Am J Infect Control 2000; 28:211-221.

The authors found that a perceived "safety climate" is an important variable in the hospital environment and is directly related to employee compliance with safe work practices and preventing workplace exposure incidents.

"Employees’ perceptions about the safety of their hospital significantly influences their adoption of safe work practices, which could range from the use of barrier protective devices to consistent and correct use of safety needle devices, to adherence to vaccination recommendations and much more," they emphasized. In the hospital where the study was conducted, the patient prevalence rates for bloodborne pathogens is high; the rates in adult emergency department patients are 12% for HIV, 5.1% for hepatitis B virus, and 18.2% for hepatitis C virus.

"However, even in hospitals with lower rates, the adverse effect of exposure incidents on both employees and the organization is so great that efforts to improve hospital safety climate will almost certainly be highly cost-effective," they note. "Administrations that are supportive of strong safety climates will not only improve compliance with safe work practices, thereby reducing exposure risk, but also will benefit from the far-reaching implications inherent in the safety climate message. When employee safety is considered and valued, employees feel valued."

A questionnaire, which included 46 safety climate items, was developed and tested on a sample of 789 hospital-based health care workers at risk for bloodborne pathogen exposure incidents. The researchers developed a 20-item hospital safety climate scale that measures hospitals’ commitment to bloodborne pathogen risk management programs. The safety climate scale included six different organizational dimensions: senior management support for safety programs; absence of workplace barriers to safe work practices; cleanliness and orderliness of the work site; minimal conflict and good communication among staff members; frequent safety-related feedback/training by supervisors; and availability of personal protective equipment and engineering controls. Of these, senior management support for safety programs, absence of workplace barriers to safe work practices, and cleanliness/orderliness of the work site were significantly related to compliance. In addition, both senior management support for safety programs and frequent safety-related feedback/ training were significantly related to workplace exposure incidents.

"The most significant finding in terms of enhancing compliance and reducing exposure incidents was the importance of the perception that senior management was supportive of the bloodborne pathogen safety program," they conclude.