Molecular Characterization of Carbapenem-Resistant Acinetobacter baumannii Isolated from the Intensive Care Unit in a Tertiary Teaching Hospital in Malaysia.

Jia Jie Woon,Kartini Abdul Jabar,Sasheela Ponnampalavanar,Chun Wie Chong,Nuryana Idris,Cindy Shuan Ju Teh

doi:10.3390/antibiotics10111340

Abstract

The emergence of carbapenem-resistant Acinetobacter baumannii (CRAB) has now become a global sentinel event. CRAB infections often instigate severe clinical complications and are potentially fatal, especially for debilitated patients. The present study aimed to conduct molecular characterization on CRAB isolated from patients in the intensive care unit from 2015 to 2016 and determine the risk factors associated with patients’ mortality. One hundred CRAB isolates were retrospectively selected and included in this study. Antimicrobial susceptibility testing showed that all isolates remained susceptible to colistin, even though 62% of them conferred resistance to all other classes of antibiotics tested. OXA carbapenemase gene was found to be the predominant carbapenemase gene, with 99% of the isolates coharbouring blaOXA-23-like and blaOXA-51-like carbapenemase genes. All isolates were carrying intact CarO genes, with the presence of various degree of nucleotide insertion, deletion and substitution. Overall, PFGE subtyped the isolates into 13 distinct pulsotypes, with the presence of 2 predominant pulsotypes. Univariate analysis implied that age, infection/colonization by CRAB, ethnicity, comorbidity and CRAB specimen source were significantly associated with in-hospital mortality. Multivariate analysis identified a higher risk of mortality for patients who are of Chinese ethnicity with diabetes as an underlying disease. As CRAB infection could lead to high rate of mortality, comprehensive infection control measures are needed to minimize the spread of this pathogen.

Highlights

Acinetobacter baumannii has gained notoriety as one of the most prevalent nosocomial pathogens, causing substantial mortality and economic burden to hospitalized patients [1]
Complete clinical data for 89 out of 100 patients with carbapenem-resistant Acinetobacter baumannii (CRAB) isolated during intensive care units (ICUs) admission were available and included in the analysis
Rapid emergence of CRAB in healthcare settings imposes a great threat for patients’ well-being, and the dissemination of strains with extremely resistant phenotypes will inevitably compromise the treatment of CRAB infection in vulnerable groups

Summary

Introduction

Acinetobacter baumannii has gained notoriety as one of the most prevalent nosocomial pathogens, causing substantial mortality and economic burden to hospitalized patients [1]. It is found predominantly in intensive care units (ICUs), affecting debilitated patients with compromised immunity, disrupted normal flora or barrier integrity [1]. Global surveillance estimated an incidence rate of A. baumannii infections at about 1,000,000 cases annually, of which more than half are associated with carbapenem resistance [5]. Carbapenem-resistant Acinetobacter baumannii (CRAB) is gaining global concern, to the extent that the World Health Organization has classified it as one of the critical priority pathogens that needs urgent research, discovery and development of new antibiotics [6]. In Malaysia, based on the National Surveillance of Antibiotic Resistance (NSAR), the rate of carbapenem resistance had risen from 49% in 2008 to 61% in 2016 and remained fairly constant at 60% yearly afterward [8]

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