Abstract
BackgroundAcinetobacter baumannii are of major human health importance because they cause life-threatening nosocomial infections and often are highly resistant to antimicrobials. Specific multidrug-resistant A. baumannii lineages are implicated in hospital outbreaks globally. We retrospectively investigated a suspected outbreak of carbapenem-resistant A. baumannii (CRAB) colonizing patients in an intensive care unit (ICU) of a tertiary hospital in Southwest Nigeria where genomic surveillance of Acinetobacter has hitherto not been conducted.MethodsA prospective observational study was conducted among all patients admitted to the ICU between August 2017 and June 2018. Acinetobacter species were isolated from rectal swabs and verified phenotypically with the Biomerieux Vitek 2 system. Whole genome sequencing (WGS) was performed on the Illumina platform to characterize isolates from a suspected outbreak during the study period. Phylogenetic analysis, multilocus sequence typing, and antimicrobial resistance gene prediction were carried out in silico.ResultsAcinetobacter isolates belonging to the A. baumannii complex were recovered from 20 (18.5%) ICU patients. Single nucleotide polymorphism (SNP) analysis and epidemiological information revealed a putative outbreak clone comprising seven CRAB strains belonging to the globally disseminated international clone (IC) 2. These isolates had ≤2 SNP differences, identical antimicrobial resistance and virulence genes, and were all ST1114/1841.ConclusionWe report a carbapenem-resistant IC2 A. baumannii clone causing an outbreak in an ICU in Nigeria. The study findings underscore the need to strengthen the capacity to detect A. baumannii in human clinical samples in Nigeria and assess which interventions can effectively mitigate CRAB transmission in Nigerian hospital settings.
Highlights
Acinetobacter baumannii are opportunistic pathogens of increasing global public health concern
Rectal swab samples were obtained from 108 patients admitted to the intensive care unit (ICU) at Obafemi Awolowo University Teaching Hospitals Complex (OAUTHC) between August 2017 and June 2018
As the suspected outbreak isolates within clade 1 were close to identical (≤2 single nucleotide polymorphism (SNP)), we further investigated the reason for the different sequence types (STs) assignments of the isolates within this clade
Summary
Acinetobacter baumannii are opportunistic pathogens of increasing global public health concern. These Gram-negative organisms are widely implicated in life-threatening drugresistant infections in hospitalized patients. A. baumannii are often introduced in patients through contaminated medical devices, and infections include pneumonia, urinary tract infection, bloodstream infection, endocarditis, meningitis and wound infection [1]. More so, these infections are often prone to epidemic spread within hospital settings, facilitated by the excellent ability of A. baumannii to survive in harsh hospital environments [2]. Acinetobacter baumannii are of major human health importance because they cause life-threatening nosocomial infections and often are highly resistant to antimicrobials. We retrospectively investigated a suspected outbreak of carbapenem-resistant A. baumannii (CRAB) colonizing patients in an intensive care unit (ICU) of a tertiary hospital in Southwest Nigeria where genomic surveillance of Acinetobacter has hitherto not been conducted
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