Outbreak and control of Achromobacter denitrificans at an academic hospital in Pretoria, South Africa

Abstract

Objective: In this study, we sought to determine the source of an outbreak of Achromobacter denitrificans infections in patients at a tertiary-care academic hospital. Design: Outbreak report study with intervention. The study period extended from February 2018 to December 2018. Setting: The study was conducted at a tertiary-care academic hospital in Pretoria, South Africa. Patients and participants: All patients who cultured A. denitrificans from any site were included in this study. During the study period, 43 patients met this criterion. Interventions: Once an outbreak was confirmed, the microbiology laboratory compiled a list of affected patients. A common agent, chlorhexidine-and-water solution, was used as a disinfectant–antiseptic for all affected patients. The laboratory proceeded to culture this solution. Environmental and surface swabs were also cultured from the hospital pharmacy area where this solution was prepared. Repetitive-element, sequence-based, polymerase chain reaction (rep-PCR) was performed on the initial clinical isolates to confirm the relatedness of the isolates. Results: In total, 43 isolates of A. denitrificans were cultured from patient specimens during the outbreak. The laboratory cultured A. denitrificans from all bottles of chlorhexidine-and-water solutions sampled from the wards and the pharmacy. The culture of the dispenser device used to prepare this solution also grew A. denitrificans. The rep-PCR confirmed the clonality of the clinical isolates with 2 genotypes dominating. Conclusions: Contaminated chlorhexidine-and-water solutions prepared at the hospital pharmacy was determined to be the source of the outbreak. Once this item was removed from the hospital, the laboratory did not culture any further A. denitrificans isolates from patient specimens.

Current viewpoint on the epidemiology of nonfermenting Gram-negative bacterial strains

“…Several hospital outbreaks, particularly BSIs and pneumonias originating from antiseptic solutions, medication vials, hot water taps, saline solutions, chlorhexidine mouth washes, high touch surfaces, ventilation systems, cleansing foams and hemodialysis systems have been reported, due to Achromobacter spp., Elizabethkingia spp., Sphingomonas spp. and B. cepacia [57 ▪ ,58,59]. It should be emphasized that pseudoinfections may sometimes mimic outbreaks when certain NFGNB are isolated from clinical specimens in the absence of befitting clinical syndrome.…”