Sequential outbreaks in a Spanish hospital caused by multiresistant OXA-58-producing Acinetobacter baumannii ST92

Abstract

The aim of this study was to assess the epidemiology and molecular basis of the infection and dissemination of multidrug-resistant Acinetobacter baumannii (MDRAB) in three sequential outbreaks at the intensive care units (ICUs) of a tertiary university hospital in Granada, Spain, between 2009 and 2011. Strains from all patients infected and/or colonized by MDRAB during outbreak periods were characterized using PFGE and multilocus sequence typing (MLST). The first outbreak appeared in the summer of 2009 involving 38 ICU patients: 25 from a Traumatology-Rehabilitation hospital (TRH) and 13 from a Medical-Surgery hospital (MSH). Between 2010 and 2011, outbreaks were limited to the MSH-ICU, affecting 9 and 11 patients, respectively. Two PFGE types were detected. In the 2009 outbreak, two clones were identified: profile 1 strains were isolated at the TRH, whilst profile 2 was isolated at the MSH. Only one clone was identified in the 2010 and 2011 outbreaks: the profile 2 clone detected at the MSH in 2009. After MLST analysis, a single sequence type (ST92) was identified. This suggested that an endemic strain could evolve and cause localized outbreaks in vulnerable patients. Multiplex PCR for OXA group enzymes yielded a positive result for bla OXA-58-like and bla OXA-51-like genes, and gene sequencing showed the presence of bla OXA-58 . However, the absence of ISAba1 upstream of the bla OXA-51-like gene suggested the absence of OXA-51 expression. The susceptibility pattern was not an appropriate method for MDRAB surveillance, as several susceptibility patterns were identified in a single clone. Consequently, molecular methods of characterization are recommended for epidemiological surveillance of MDRAB.

Insufficient Discriminatory Power of Matrix-Assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry Dendrograms to Determine the Clonality of Multi-Drug-ResistantAcinetobacter baumanniiIsolates from an Intensive Care Unit

“…Multi-drug-resistant (MDR) Acinetobacter baumannii ( A. baumannii ) outbreaks have been recognized as an increasing threat in hospitals. Numerous nosocomial outbreaks of A. baumannii , especially in intensive care units (ICUs), have been reported [ 9 , 10 ]. The application of MALDI-TOF MS for the rapid detection of carbapenem resistance in a large series of A. baumannii clinical isolates has been evaluated [ 11 , 12 ]; however, the application of A. baumannii MALDI-TOF MS dendrograms has never been reported.…”

Next-Generation Sequencing and Comparative Analysis of Sequential Outbreaks Caused by Multidrug-Resistant Acinetobacter baumannii at a Large Academic Burn Center

“…Although sequential hospital outbreaks of MDRAB have been reported (16)(17)(18)(19)(20)(21)(22), there are very few studies that apply NGS for MDRAB strain typing in this setting. Here, we describe the molecular investigation of this outbreak, showing that this actually represents several sequential outbreaks within the burn unit.…”

A Locked Nucleic Acid (LNA)-Based Real-Time PCR Assay for the Rapid Detection of Multiple Bacterial Antibiotic Resistance Genes Directly from Positive Blood Culture

“…The mechanism of drug resistance is related with the acquisition of enzymes that inactivate antibiotic molecules or target gene mutation. A series of drug resistance genes have been identified, including mec A, van A, and van B in gram-positive bacteria [ 2 – 4 ] and extended-spectrum β-lactamase (ESBL) genes, plasmid-acquired AmpC lactamases (pAmpC) genes [ 5 , 6 ], and carbapenemase genes [ 7 – 11 ] in gram-negative bacteria. The rapid and accurate detection of drug resistance genes prior to treatment is very important for the selection of effective antibiotics to control infection.…”