ABSTRACT
Nosocomial infections occur worldwide and also in the Kurdistan region. Frequently patients colonized with multiresistant Pseudomonas aeruginosa isolates are encountered in many hospitals. As information is lacking with respect to the mechanisms of resistance responsible for the multiresistant character of the P. aeruginosa isolates and their genetic relationship, isolates were prospectively collected and characterized with respect to their mechanism of resistance. During 2012 and 2013, 81 P. aeruginosa isolates were collected from three teaching hospitals in the city of Erbil, Iraq. Susceptibility testing was performed using the VITEK-2 system. Isolates were screened for the presence of extended-spectrum ß-lactamases (ESBLs) and for the presence of metallo ß-lactamases (MBLs). The presence of serine carbapenemases was detected by PCR. The genetic relationship of the isolates was demonstrated by amplified fragment length polymorphism (AFLP). Susceptibility results revealed high rates of resistance against all classes of antibiotics except polymyxins. Genetic characterization demonstrated the presence of ESBL-genes, that is, blaVEB (30%) and blaPER (17%), also ESBL blaPME was detected in four isolates. AFLP typing revealed clonal spread of blaVEB, blaPER, and three clusters of blaOXA-10-positive isolates. Only one isolate was MBL (blaVIM) positive. Of a selected number of isolates (n = 11), whole-genome sequencing analysis revealed that these isolates belonged to "high-risk" MLSTs ST244, ST235, ST308, and ST654. This study reveals the presence and clonal spread of widely resistant high-risk clones of P. aeruginosa in Iraqi Kurdistan. As far as we are aware, this is the first report of multiple, polyclonal, PME producing P. aeruginosa outside the Arabian Peninsula.
Subject(s)
Cross Infection/microbiology , Drug Resistance, Multiple, Bacterial/genetics , Genes, Bacterial/genetics , Pseudomonas Infections/microbiology , Pseudomonas aeruginosa/genetics , Pseudomonas aeruginosa/isolation & purification , beta-Lactamases/genetics , Amplified Fragment Length Polymorphism Analysis/methods , Anti-Bacterial Agents/pharmacology , Bacterial Proteins/genetics , Cross Infection/drug therapy , Drug Resistance, Multiple, Bacterial/drug effects , Humans , Iraq , Microbial Sensitivity Tests/methods , Polymerase Chain Reaction/methods , Polymorphism, Restriction Fragment Length/genetics , Pseudomonas Infections/drug therapy , Pseudomonas aeruginosa/drug effectsABSTRACT
In addition to intrinsic resistance in Acinetobacter baumannii, many different types of acquired resistance mechanisms have been reported, including the presence of VIM and IMP metallo ß-lactamases and also of blaOXA-23-like and blaOXA-58-like enzymes. In the Kurdistan region of Iraq, the multiresistant A. baumannii-calcoaceticus complex is prevalent. We characterized the different mechanisms of resistance present in clinical isolates collected from different wards and different hospitals from the Kurdistan region. One hundred twenty clinical nonduplicate A. baumannii-calcoaceticus complex isolates were collected from four hospitals between January 2012 and October 2013. The identification of the isolates was confirmed by MALDI-TOF. The susceptibility to different antibiotics was determined by disk diffusion and analyzed in accordance to EUCAST guidelines. By PCR, the presence of blaOXA-51-like, blaOXA-23-like, blaOXA-24-like, and blaOXA-58-like genes was determined as well as the presence of the insertion element ISAba1. Clonal diversity was analyzed by pulsed-field gel electrophoresis (PFGE) using the restriction enzyme ApaI and, in addition, multilocus sequence typing (MLST) was performed on a selected subset of 15 isolates. All 120 A. baumannii isolates harbored blaOXA-51-like genes. One hundred one out of 110 (92%) imipenem (IMP)-resistant A. baumannii-calcoaceticus complex isolates additionally carried the blaOXA-23-like gene and four isolates (3%) were positive for blaOXA-24-like. All 101 blaOXA-23-like-positive isolates had the ISAba1 insertion sequence, 1,600 bp upstream of the blaOXA-23-like gene. The blaOXA-58-like gene was not detected in any of the 110 IMP-resistant strains. Eight different PFGE clusters were identified and distributed over the different hospitals. MLST analysis performed on a subset of 15 representative isolates revealed the presence of the international clone ST2 (Pasteur). Besides ST2 (Pasteur), also many other STs (Pasteur) were encountered such as ST136, ST94, ST623, ST792, and ST793, all carrying the blaOXA-23 gene. In clinical A. baumannii-calcoaceticus complex isolates from Kurdistan-Iraq, the blaOXA-23 gene in combination with the upstream ISAba1 insertion element is largely responsible for carbapenem resistance. Several small clusters of identical genotypes were found from patients admitted to the same ward and during overlapping time periods, suggesting transmission within the hospital. Identification of source(s) and limiting the transmission of these strains to patients needs to be prioritized.
