Cutaneous Melioidosis Cluster Caused by Contaminated Wound Irrigation Fluid.

Abstract

Melioidosis, caused by infection with the bacterium Burkholderia pseudomallei, is a disease with manifestations ranging from rapidly fatal septicemia, pneumonia, or meningoencephalitis to localized abscess formation, cellulitis, and asymptomatic seroconversion. This disease occurs most commonly in Southeast Asia and northern Australia after exposure to contaminated soil or surface water (1). The US National Notifiable Diseases Surveillance Systems case definition describes cutaneous melioidosis as “an acute or chronic localized infection which may or may not include symptoms of fever and muscle aches. Such infection often results in ulcer, nodule, or skin abscess” (2). Sporadic cases outside melioidosis-endemic regions usually occur in persons who have a history of travel in the tropics, which can be as long as several decades previously because of the ability of B. pseudomallei to persist undetected after the initial inoculation event (3). In these cases, B. pseudomallei infection might not be considered in the differential diagnosis. Detection of sporadic cases of melioidosis by clinical pathology laboratories requires microbiology laboratories to have robust bacterial identification procedures. Even with advanced equipment, a lack of awareness of the characteristic features of B. pseudomallei can result in misidentification of cultured organisms (4). Only a few point-source outbreaks of melioidosis have been reported (5). Two of these occurred in Western Australia; 1 was attributed to movement of livestock from the tropical north to the temperate southwest (6), and the other was caused by contamination of a potable water supply (7). Neither cluster was healthcare-associated. Only a few cases of healthcare-associated melioidosis have been reported. Some of the earliest accounts of melioidosis identified opiate injection as a potential source of infection (8). In animal healthcare, injected medication was thought responsible for a series of animal infections in northern Australia (9). The first report of hospital-acquired melioidosis originated in Hawaii, USA, and described pulmonary infection after bronchoscopy with a scope contaminated with B. pseudomallei (10). This report indicated that the contaminated bronchoscope had previously been used on a returned traveler with melioidosis. A second report described 2 patients with B. pseudomallei urinary tract infection on different wards of a hospital on whose grounds B. pseudomallei was isolated (11). Nosocomial contamination associated with faulty hospital hygiene and ineffective disinfectant solution was reported from a hospital in Thailand treating patients with melioidosis (12). More recently, cases of neonatal melioidosis from a hospital in Thailand were thought to be healthcare-associated, although the full details of transmission could not be determined (13). Melioidosis became a notifiable infection in Western Australia in January 2000 (14). Physicians, pathology service providers, and the state public health laboratory are required to report a diagnosis of melioidosis to the State Disease Control Directorate. Melioidosis notification is largely laboratory-generated in Western Australia because confirmation of infection according to the Australian Laboratory Case Definition relies on culture of B. pseudomallei from clinical specimens. Pathology service providers therefore routinely refer presumptive B. pseudomallei isolates to the state public health laboratory for confirmation, genotyping, and archiving in a reference culture collection (Western Australian Burkholderia Collection). Here we report the laboratory investigation of a cluster of cutaneous melioidosis in the temperate southwest of Australia, the identification of its source, and means of control.