Chapter 125. Health Care– Associated Infections (Part 9) Tuberculosis Important measures for the control of tuberculosis (Chap. 158) include prompt recognition, isolation, and treatment of cases; recognition of atypical presentations (e.g., lower-lobe infiltrates without cavitation); use of negative- pressure, 100% exhaust, private isolation rooms with closed doors and 6–12 or more air changes per hour; use of N95 "respirators" (approved by the National Institute for Occupational Safety and Health) by caregivers entering isolation rooms; possible use of high-efficiency particulate air filter units and/or ultraviolet lights for disinfecting air when other engineering controls are not feasible or reliable; and follow-up skin-testing of susceptible personnel who have been exposed to infectious patients before isolation. The use of new serologic tests, rather than skin tests, in the diagnosis of latent tuberculosis for infection control purposes is being studied. Group a Streptococcal Infections The potential for an outbreak of group A streptococcal infection (Chap. 130) should be considered when even a single nosocomial case occurs. Most outbreaks involve surgical wounds and are due to the presence of an asymptomatic carrier in the operating room. Investigation can be confounded by carriage at extrapharyngeal sites such as the rectum and vagina. Health care workers in whom carriage has been linked to nosocomial transmission of group A streptococci are removed from the patient-care setting and are not permitted to return until carriage has been eliminated by antimicrobial therapy. Fungal Infections Fungal spores are common in the environment, particularly on dusty surfaces. When dusty areas are disturbed during hospital repairs or renovation, the spores become airborne. Inhalation of spores by immunosuppressed (especially neutropenic) patients creates a risk of pulmonary and/or paranasal sinus infection and disseminated aspergillosis (Chap. 197). Routine surveillance among neutropenic patients for infections with filamentous fungi, such as Aspergillus and Fusarium, helps hospitals to determine whether they are facing unduly extensive environmental risks. As a matter of routine, hospitals should inspect and clean air- handling equipment, review all planned renovations with infection-control personnel and subsequently construct appropriate barriers, remove immunosuppressed patients from renovation sites, and consider the use of high- efficiency particulate air intake filters for rooms housing immunosuppressed patients. Legionellosis Nosocomial Legionella pneumonia (Chap. 141) is most often due to contamination of potable water and predominantly affects immunosuppressed patients, particularly those receiving glucocorticoid medication. The risk varies greatly within and among geographic regions, depending on the extent of hospital hot-water contamination and on specific hospital practices (e.g., inappropriate use of nonsterile water in respiratory therapy equipment). Laboratory-based surveillance for nosocomial Legionella should be performed, and a diagnosis of legionellosis should probably be considered more often than it is. If cases are detected, environmental samples (e.g., tap water) should be cultured. If cultures yield Legionella and if typing of clinical and environmental isolates reveals a correlation, eradication measures should be pursued. An alternative approach is to periodically culture tap water in wards housing high-risk patients. If Legionella is found, a concerted effort should be made to culture samples from all patients with nosocomial pneumonia for Legionella. Antibiotic-Resistant Bacteria Control of antibiotic resistance, particularly in outbreaks (Table 125-3), depends on close laboratory surveillance, with early detection of problems; on aggressive reinforcement of routine asepsis (e.g., hand hygiene); on implementation of barrier precautions for all colonized and/or infected patients; on use of patient-surveillance cultures to more fully ascertain the extent of patient colonization; and on timely initiation of an epidemiologic investigation when rates increase. Colonized personnel who are implicated in nosocomial transmission and patients who pose a threat may be decontaminated. In a few ICUs, selective decontamination of patients has been used successfully as a temporary emergency control measure for outbreaks of infection due to gram-negative bacilli. Other promising ICU control measures include daily bathing of patients with chlorhexidine and enforcement of environmental cleaning; in recent trials, each of these measures reduced cross-transmission of VRE. The value of "search-and- destroy" methods—i.e., the use of active surveillance cultures to detect and isolate the "resistance iceberg" of patients colonized with methicillin-resistant S. aureus (MRSA) or VRE—in non-outbreak settings has been controversial but is credited with elimination of nosocomial MRSA in the Netherlands and Denmark. . Chapter 125. Health Care– Associated Infections (Part 9) Tuberculosis Important measures for the control of tuberculosis. of N95 "respirators" (approved by the National Institute for Occupational Safety and Health) by caregivers entering isolation rooms; possible use of high-efficiency particulate air. latent tuberculosis for infection control purposes is being studied. Group a Streptococcal Infections The potential for an outbreak of group A streptococcal infection (Chap. 130) should