Brucella Exposure Risk Events in 10 Clinical Laboratories, New York City, USA, 2015 to 2017

Abstract

From 2015 to 2017, 11 confirmed brucellosis cases were reported in New York City, leading to 10 Brucella exposure risk events (Brucella events) in 7 clinical laboratories (CLs). Most patients had traveled to countries where brucellosis is endemic and presented with histories and findings consistent with brucellosis. CLs were not notified that specimens might yield a hazardous organism, as the clinicians did not consider brucellosis until they were notified that bacteremia with Brucella was suspected. In 3 Brucella events, the CLs did not suspect that slow-growing, small Gram-negative bacteria might be harmful. Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS), which has a limited capacity to identify biological threat agents (BTAs), was used during 4 Brucella events, which accounted for 84% of exposures. In 3 of these incidents, initial staining of liquid media showed Gram-positive rods or cocci, including some cocci in chains, suggesting streptococci. Over 200 occupational exposures occurred when the unknown isolates were manipulated and/or tested on open benches, including by procedures that could generate infectious aerosols. During 3 Brucella events, the CLs examined and/or manipulated isolates in a biological safety cabinet (BSC); in each CL, the CL had previously isolated Brucella Centers for Disease Control and Prevention recommendations to prevent laboratory-acquired brucellosis (LAB) were followed; no seroconversions or LAB cases occurred. Laboratory assessments were conducted after the Brucella events to identify facility-specific risks and mitigations. With increasing MALDI-TOF MS use, CLs are well-advised to adhere strictly to safe work practices, such as handling and manipulating all slow-growing organisms in BSCs and not using MALDI-TOF MS for identification until BTAs have been ruled out.

Keywords: biosafety; brucellosis; laboratory-acquired infection; risk assessment.

FIG 1

Gram stains of Brucella spp. growing in blood culture broth may be mistaken for common Gram-positive organisms. Gram stains from three clinical laboratories of blood culture bottles that ultimately yielded Brucella spp. The slow-growing Gram-positive bacilli (A), Gram-positive rods and Gram-positive cocci in chains (B), and Gram-positive cocci in pairs and chains (C) were mistaken initially for streptococci or diphtheroids. Following streaking of blood culture broth on agar plates, Gram stains of colonies yielded small, Gram-negative organisms more typical of Brucella (Table 2).