Abstract & Commentary: Group A strep strikes 24 health care workers
Are standard precautions adequate?
Source: Kakis A, et al. An outbreak of group A streptococcal infection among health care workers. Clin Infect Dis 2002; 35:1,353-1,359.
Abstract: A patient with group A streptococcal respiratory and soft tissue infection was the source of an outbreak involving 24 health care workers.
A previously healthy 43-year-old woman presented to the emergency department with bullae involving her left breast. She had had the onset of fever and upper respiratory symptoms three days earlier. Over several hours, the lesions of the breast began to coalesce and spread, followed by sloughing. She developed vomiting, diarrhea, renal failure, and respiratory distress. Chest X-ray showed pulmonary infiltrates.
The woman was admitted to the critical care unit and underwent nasotracheal intubation. Group A streptococci (GAS) were isolated from blood, respiratory secretions, and soft tissue. She was treated with vancomycin, piperacillin-tazobactam, clindamycin, intravenous immuglobulin, and hemodialysis. On the sixth hospital day, she underwent mastectomy; there was extensive tissue necrosis along with multiple abscesses. The patient ultimately died on hospital day 17.
On hospital day 4, three intensive care unit nurses complained of sore throat and fever. Initial surveillance identified 20 symptomatic staff who had direct patient contact. Of these, a total of 10 had positive pharyngeal cultures for GAS. Expanded culture surveillance of asymptomatic staff who had patient contact identified a total of 24 culture-positive individuals, and one symptomatic physician who treated himself with penicillin before undergoing culture (he was included as a case). Isolates from the culture-positive staff were compared with the source patient’s isolates by DNA typing.
Twenty-three had a DNA pattern identical to that of the patient. The employee with a different pattern had two children at home with GAS pharyngitis; her isolate was identical to that of her children. Thus, there were 24 nosocomial cases of GAS infection among hospital staff. All infected staff had had contact with the patient within the first 25 hours after presentation.
All staff received treatment with penicillin or a macrolide. There were no secondary cases among patients or families.
Commentary by Robert Muder, MD, hospital epidemiologist at the Pittsburgh VA Medical Center
This outbreak of GAS infection is unusual in that it involved a large number of hospital staff exposed over a relatively short period of time. One contributing factor may have been the streptococcal isolate. It was M type 1, and produced NADase. These factors have been associated with invasiveness and transmissibility.
The extensive nature of the patient’s infection was no doubt a contributing factor, as well. In addition to extensive skin and soft tissue infection, she also had GAS pneumonia and underwent nasotracheal intubation shortly after admission. Thus, there would have been ample opportunity for both contact and respiratory droplet transmission.
In a survey of compliance with infection control procedures done after the outbreak, staff caring for the patient nearly always wore gloves, but rarely wore gowns or masks. Although none of the staff involved in this outbreak had serious sequelae, a large number of employees required antibiotic therapy and a minimum of 24 hours of exclusion from work. Had there been secondary cases among patients, additional morbidity or even mortality might have occurred.
The most recent Centers for Disease Control and Prevention (CDC) guidelines for isolation procedures in hospitals recommend droplet precautions (e.g., private room and masks) for pediatric, but not adult, patients with GAS pharyngitis or pneumonia. Although one hesitates to draw sweeping conclusions, this report indicates that standard precautions may be inadequate for patients with pneumonia or very extensive soft tissue infection due to GAS.
Given the potential seriousness of an outbreak of GAS in a hospital, I would recommend that such patients be managed with both contact and droplet precautions until at least 24 hours after institution of effective antibiotic therapy.
A patient with group A streptococcal respiratory and soft tissue infection was the source of an outbreak involving 24 health care workers.
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