Abstract
Background/aim: Acinetobacter baumannii is one of the most commonly encountered as multiresistance microorganism. This study was designated for investigating of β-lactamases resistance genes and aminoglycosides modifying enzymes (AMEs) in Acinetobacter baumannii isolated from Iraqi patients. Materials and methods: A total of 36 A. baumannii isolates were recovered from hospitalized Iraqi patients during May to September 2012. Antibiotic susceptibility test was performed against aminoglycosides antibiotics and phenotypic detection of slactamases was done using Extended Spectrum Beta Lacatmases (ESβL) strip. Polymerase Chain Reaction (PCR) amplification was achieved for investigating β-lactamases genes (blaSHV, blaTEM, and blaCTX) and aminoglycosides modifying enzymes (aac(6)Ib, ant(4')-IIb, aa(c) 3′ and aph(3′)-VI). Results: Out of 36 A. baumannii isolates, 15 (41.66%) were resistant to aminoglycosides antibiotics according to disk diffusion method. 17 (47.22%) isolates gave positive results in the preliminary screening of β-lactamases, the ESβLs type and AmpC enzyme, while 13 (36.11% ) of the isolates gave a positive result in Metallo-βlactamases production test. PCR analysis demonstrated that blaTEM was detected in 3 (20%) of the resistant isolates , blaSHV was detected in 9 (60%) , blaCTX-M was detected in 11 (73.33%), aac (6)-Ib was detected in 7 (46.66%), ant(4')-IIb was detected in 5(33.33%) , aph(3′)-VI in 2 (13.33%), and aa(c) 3′ was found in 10 (66.66%) of the resistant isolates. Conclusion: Local A. baumannii isolates with AMEs and β-lactamases genes represent a powerful nosocomial pathogen that threat the antibiotic era and life of immunocompromied and hospitalizes patients and this should be taken into account to find a new ways for the restriction of these powerful pathogens.
Highlights
Acinetobacter baumannii is an emerging pathogen responsible for causing a wide range of nosocomial infections, including pneumonia, urinary tract infections, and septicemia in immunocompromied patients (Karlowsky et al, 2003)
Out of 36 A. baumannii isolates, 15 (41.66%) were resistant to aminoglycosides antibiotics according to disk diffusion method. 17 (47.22%) isolates gave positive results in the preliminary screening of β-lactamases, the ESβLs type and AmpC enzyme, while 13 (36.11% ) of the isolates gave a positive result in Metallo-β- lactamases production test
Polymerase Chain Reaction (PCR) analysis demonstrated that blaTEM was detected in 3 (20%) of the resistant isolates, blaSHV was detected in 9 (60%), blaCTX-M was detected in 11 (73.33%), aac (6)-Ib was detected in 7 (46.66%), ant(4')-IIb was detected in 5(33.33%), aph(3′)-VI in 2 (13.33%), and aa(c) 3′ was found in 10 (66.66%) of the resistant isolates
Summary
Acinetobacter baumannii is an emerging pathogen responsible for causing a wide range of nosocomial infections, including pneumonia, urinary tract infections, and septicemia in immunocompromied patients (Karlowsky et al, 2003). Extensive use of antimicrobial chemotherapy within hospitals has contributed to the emergence and procreation of A. baumannii strains which are resistant to a wide range of antibiotics, including broad spectrum βlactams, aminoglycosides, and fluoroquinolones (Asadollahi et al, 2012). Aminoglycoside modifying enzymes (AMEs) catalyze the modification at different −OH or −NH2 groups of the 2-deoxystreptamine nucleus or the sugar moieties and can be nucleotidyltranferases, phosphotransferases, or acetyltransferases (Ramirez and Tolmasky, 2010). The emergence of aminoglycoside-inactivating enzymes has contributed to the diminished use of several aminoglycoside antibiotics and the presence of these types of enzymes have been found in A. baumannii, often occurring in combination (Arya, 2007, Seward et al, 1998)
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