Hot and steamy: outbreak of Bacillus cereus in Singapore associated with construction work and laundry practices

Summary Background A sudden increase in invasive infections caused by Bacillus cereus group organisms prompted an investigation at the National University Hospital in Singapore. Aim To describe the investigation and management and subsequent difficulties controlling the outbreak. Methods Clinical case reviews were performed on all patients with B. cereus group recovered from clinical samples. Widespread environmental sampling was performed followed by review of hospital ventilation systems, domestic cleaning and laundry practices. Findings B. cereus was recovered from 171 patients during a six-month period coinciding with large-scale construction work beside the hospital. Most patients presented with bacteraemia (146/171; 85.4%) with 46/171 (26.9%) requiring extended treatment courses with vancomycin or other interventions. Sampling confirmed extensive airborne dispersal inside the hospital, including isolation rooms and air-conditioned wards. Hospital linen was heavily contaminated [7403 cfu/cm2 ; 95% confidence interval (CI): 6349–8457; for 30 towels sampled], encouraged by inappropriate storage in airtight plastic bags (4437 cfu/cm2 ; CI: 3125–5750) compared with storage in porous canvas bags (166 cfu/cm2 ; CI: 76–256; P