scholarly journals Prevalence and Genetic Characterization of Carbapenem- and Polymyxin-Resistant Acinetobacter baumannii Isolated from a Tertiary Hospital in Terengganu, Malaysia

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Soo-Sum Lean ◽  
Zarizal Suhaili ◽  
Salwani Ismail ◽  
Nor Iza A. Rahman ◽  
Norlela Othman ◽  
...  
Keyword(s):  
Acinetobacter Baumannii ◽  
Polymyxin B ◽  
Tertiary Hospital ◽  
Multidrug Resistant ◽  
Resistant Isolate ◽  
The Novel ◽  
Carbapenem Resistant ◽  
Lipopolysaccharide Biosynthesis ◽  
Additional Resistance

Nosocomial infection caused by Acinetobacter baumannii is of great concern due to its increasing resistance to most antimicrobials. In this study, 54 nonrepeat isolates of A. baumannii from the main tertiary hospital in Terengganu, Malaysia, were analyzed for their antibiograms and genotypes. Out of the 54 isolates, 39 (72.2%) were multidrug resistant (MDR) and resistant to carbapenems whereas 14 (25.9%) were categorized as extensive drug resistant (XDR) with additional resistance to polymyxin B, the drug of “last resort.” Pulsed-field gel electrophoresis analyses showed that the polymyxin-resistant isolates were genetically diverse while the carbapenem-resistant isolates were clonally related. The 14 XDR isolates were further investigated for mutations in genes known to mediate polymyxin resistance, namely, pmrCAB, and the lipopolysaccharide biosynthesis genes, lpxA, lpxC, lpxD, and lpsB. All 14 isolates had a P102H mutation in pmrA with no mutation detected in pmrC and pmrB. No mutation was detected in lpxA but each polymyxin-resistant isolate had 2–4 amino acid substitutions in lpxD and 1-2 substitutions in lpxC. Eight resistant isolates also displayed a unique H181Y mutation in lpsB. The extent of polymyxin resistance is of concern and the novel mutations discovered here warrant further investigations.

scholarly journals In Vivo Selection of a Missense Mutation in adeR and Conversion of the Novel blaOXA-164 Gene into blaOXA-58 in Carbapenem-Resistant Acinetobacter baumannii Isolates from a Hospitalized Patient

2010 ◽  
Vol 54 (12) ◽  
pp. 5021-5027 ◽  
Author(s):  
Paul G. Higgins ◽  
Thamarai Schneiders ◽  
Axel Hamprecht ◽  
Harald Seifert
Keyword(s):  
Acinetobacter Baumannii ◽  
Missense Mutation ◽  
Novel Mutation ◽  
Multidrug Resistant ◽  
The Novel ◽  
Reverse Transcription Pcr ◽  
Carbapenem Resistant ◽  
Genes Encoding ◽  
Hospitalized Patient

ABSTRACT The mechanism of stepwise acquired multidrug resistance in Acinetobacter baumannii isolates from a hospitalized patient was investigated. Thirteen consecutive multidrug-resistant isolates were recovered from the same patient over a 2-month period. The Vitek 2 system identified the isolates as meropenem-sensitive Acinetobacter lwoffii; however, molecular identification showed that the isolates were A. baumannii. Etest revealed that the isolates were meropenem resistant. The presence of oxacillinase (OXA)-type enzymes were investigated by sequencing. The clonal relatedness of isolates was assessed by pulsed-field gel electrophoresis (PFGE). Expression of the genes encoding the efflux pumps AdeB and AdeJ was performed by semiquantitative real-time reverse transcription-PCR (qRT-PCR). The adeRS two-component system was sequenced. All isolates had identical PFGE fingerprints, suggesting clonal identity. The first six isolates were positive for the novel bla OXA-164 gene. The following seven isolates, recovered after treatment with a combination of meropenem, amikacin, ciprofloxacin, and co-trimoxazole showed an increase of >7-fold in adeB mRNA transcripts and a missense mutation in bla OXA-164, converting it to bla OXA-58. Sequencing revealed a novel mutation in adeR. These data illustrate how A. baumannii can adapt during antimicrobial therapy, leading to increased antimicrobial resistance.

scholarly journals Carbapenem-Resistant Acinetobacter baumannii Isolates from Tunisia Producing the OXA-58-Like Carbapenem-Hydrolyzing Oxacillinase OXA-97

2008 ◽  
Vol 52 (5) ◽  
pp. 1613-1617 ◽  
Author(s):  
Laurent Poirel ◽  
Wejdene Mansour ◽  
Olfa Bouallegue ◽  
Patrice Nordmann
Keyword(s):  
Amino Acid ◽  
Acinetobacter Baumannii ◽  
Amino Acid Substitution ◽  
Multidrug Resistant ◽  
Single Amino Acid Substitution ◽  
Single Amino Acid ◽  
The Novel ◽  
Cloning And Sequencing ◽  
Carbapenem Resistant ◽  
Genetic Structures

ABSTRACT The basis of the β-lactam resistance of 39 multidrug-resistant Acinetobacter baumannii isolates recovered from hospitalized patients was studied. These isolates were collected from 2001 to 2005 at the Sahloul Hospital in Sousse, Tunisia. They belonged to two distinct clones. One clone that grouped 19 isolates produced a carbapenem-hydrolyzing oxacillinase, OXA-97, that differed from OXA-58 by a single amino acid substitution and conferred the same β-lactam resistance profile as OXA-58. The bla OXA-97 gene was located on plasmids that varied in size in 18 isolates and was chromosomally located in a single isolate. Cloning and sequencing identified genetic structures surrounding the bla OXA-97 gene similar to those reported to be adjacent to the bla OXA-58 gene. In addition, the novel ISAba8 element (which is of the IS21 family) was identified. This is the first report of the nosocomial spread of carbapenemase producers in A. baumannii isolates in Africa.

scholarly journals In VitroPharmacodynamics of Polymyxin B and Tigecycline Alone and in Combination against Carbapenem-Resistant Acinetobacter baumannii

2013 ◽  
Vol 58 (2) ◽  
pp. 874-879 ◽  
Author(s):  
Mao Hagihara ◽  
Seth T. Housman ◽  
David P. Nicolau ◽  
Joseph L. Kuti
Keyword(s):  
Combination Therapy ◽  
Acinetobacter Baumannii ◽  
Population Analysis ◽  
Polymyxin B ◽  
Multidrug Resistant ◽  
Bacterial Killing ◽  
Content Type ◽  
Model Free ◽  
Carbapenem Resistant

ABSTRACTCarbapenem-resistantAcinetobacter baumanniiis increasing in prevalence. Polymyxin B and tigecycline are among the most active antibiotics used against this pathogenin vitro. Pastin vitrostudies, however, neglected the importance of simulating exposures observed in humans to determine their antibacterial effects. In this study, four carbapenem-resistantA. baumanniiisolates were evaluated using anin vitropharmacodynamic model. Free-drug exposures using 1 mg/kg of body weight of polymyxin B every 12 h (q12h), 100 and 200 mg tigecycline q12h, and the combination of these regimens were simulated. The microbiological responses to these treatments were measured by the change in log10CFU/ml over 24 h and the area under the bacterial killing and regrowth curve (AUBC). Resistance was assessed by a population analysis profile (PAP) conducted after 24 h of treatment. Polymyxin B achieved a reduction on the order of −2.05 ± 0.68 log10CFU/ml against theseA. baumanniiisolates, while all isolates grew to control levels with tigecycline monotherapy. Combination therapy with polymyxin B plus 200 mg tigecycline q12h achieved a greater reduction in bacterial density than did therapy with polymyxin B alone (−3.31 ± 0.71 versus −2.05 ± 0.68 log10CFU/ml,P< 0.001) but not significantly different than combination therapy with 100 mg tigecycline q12h (−2.45 ± 1.00 log10CFU/ml,P= 0.370). Likewise, combination therapy with polymyxin B plus 200 mg tigecycline q12h significantly reduced the AUBC compared to that with polymyxin B alone (62.8 ± 8.9 versus 79.4 ± 10.5 log10CFU/ml,P< 0.05). No changes in the PAP from baseline were observed for either antibiotic alone. In this study, combination therapy with simulated exposures of polymyxin B and tigecycline at an aggressive dose of 200 mg q12h produced synergistic or additive effects on humans against these multidrug-resistantA. baumanniistrains.

scholarly journals In Vitro Double and Triple Bactericidal Activities of Doripenem, Polymyxin B, and Rifampin against Multidrug-Resistant Acinetobacter baumannii, Pseudomonas aeruginosa, Klebsiella pneumoniae, and Escherichia coli

2010 ◽  
Vol 54 (6) ◽  
pp. 2732-2734 ◽  
Author(s):  
Carl Urban ◽  
Noriel Mariano ◽  
James J. Rahal
Keyword(s):  
Escherichia Coli ◽  
Pseudomonas Aeruginosa ◽  
Klebsiella Pneumoniae ◽  
Acinetobacter Baumannii ◽  
Carbapenem Resistance ◽  
Polymyxin B ◽  
Multidrug Resistant ◽  
Carbapenem Resistant ◽  
Bactericidal Activities

ABSTRACT In vitro double and triple bactericidal activities of doripenem, polymyxin B, and rifampin were assessed against 20 carbapenem-resistant clinical isolates with different mechanisms of carbapenem resistance. Bactericidal activity was achieved in 90% of all bacteria assayed using combinations of polymyxin B, doripenem, and rifampin against five each of the carbapenem-resistant Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Escherichia coli isolates studied. Combinations with these antibacterials may provide a strategy for treatment of patients infected with such organisms.

scholarly journals In Vitro Activity of Tigecycline against Multidrug-Resistant Acinetobacter baumannii and Selection of Tigecycline-Amikacin Synergy

2008 ◽  
Vol 52 (8) ◽  
pp. 2940-2942 ◽  
Author(s):  
Ellen S. Moland ◽  
David W. Craft ◽  
Seong-geun Hong ◽  
Soo-young Kim ◽  
Lucas Hachmeister ◽  
...  
Keyword(s):  
Acinetobacter Baumannii ◽  
Polymyxin B ◽  
Multidrug Resistant ◽  
Vitro Activity ◽  
Resistant Isolate ◽  
In Vitro Activity ◽  
Bactericidal Activities ◽  
Time Kill ◽  
Selection Of

ABSTRACT Polymyxin B, minocycline, and tigecycline were the most potent of 10 antibiotics against 170 isolates of multidrug-resistant Acinetobacter baumannii. In time-kill studies, the exposure of a highly tigecycline-resistant isolate to tigecycline resulted in enhanced susceptibility to amikacin and synergistic bactericidal activities of the two drugs.

scholarly journals Characterization of Carbapenem-Resistant Acinetobacter baumannii Strains Isolated from Hospitalized Patients in Palestine

2017 ◽  
Vol 2017 ◽  
pp. 1-7 ◽  
Author(s):  
Regeen Handal ◽  
Lulu Qunibi ◽  
Ibrahim Sahouri ◽  
Maha Juhari ◽  
Rula Dawodi ◽  
...  
Keyword(s):  
Acinetobacter Baumannii ◽  
Virulence Gene ◽  
Multidrug Resistant ◽  
Resistant Bacteria ◽  
Drug Resistant ◽  
Single Patient ◽  
Carbapenem Resistant ◽  
Control And Prevention ◽  
Sequence Types

The American Centers for Disease Control and Prevention (CDC) recognizes Acinetobacter baumannii as a source of global outbreaks and epidemics especially due to its increasing resistance to commercially available antibiotics. In this study, 69 single patient multidrug resistant isolates collected from all over Palestine, except Gaza, were studied. All the isolates were resistant to all the β–lactam antibiotics including the carbapenems. Of the 69 isolates, 82.6% were positive for blaOXA-23, 14.5% were positive for blaOXA-24, and 3% were positive for blaOXA-58. None were positive for blaOXA-143 and blaOXA-235. In addition, 5.8% and 0% were positive for blaNDM and blaKPC, respectively. Of the 69 isolates, none were positive for the aminoglycoside aphA6 gene while 93% were positive for the aphA1 gene. The acetyltransferases aacC1 and aacA4 genes tested positive in 22% and 13% of the isolates, respectively. The ompA biofilm-producing virulence gene was detected in all isolates. Finally, Multilocus Sequence Typing (MLST) of 13 isolates revealed that more than one strain of A. baumannii was circulating in Palestinian hospitals as results revealed that 7 isolates were of ST208, 2 isolates ST218, 1 isolate ST231, 1 isolate ST348, and 2 new Sequence Types. The detection of these drug resistant pathogens is a reminder of the importance of active surveillance for resistant bacteria in order to prevent their spread in hospital settings.

scholarly journals Genotypic and Phenotypic Characterization of Novel Sequence Types of Carbapenem-Resistant Acinetobacter baumannii, With Heterogeneous Resistance Determinants and Targeted Variations in Efflux Operons

2021 ◽  
Vol 12 ◽  
Author(s):  
Srinivasan Vijaya Bharathi ◽  
Manjunath Venkataramaiah ◽  
Govindan Rajamohan
Keyword(s):  
Acinetobacter Baumannii ◽  
Health Care Systems ◽  
Multidrug Resistant ◽  
Phenotypic Characterization ◽  
High Morbidity ◽  
Phenotype Microarray ◽  
Human Pathogens ◽  
Carbapenem Resistant ◽  
Care Systems

Acinetobacter baumannii has emerged as one of the dominant nosocomial human pathogens associated with high morbidity and mortality globally. Increased incidences of carbapenem-resistant A. baumannii (CRAB) have resulted in an enormous socioeconomic burden on health-care systems. Here, we report the genotypic and phenotypic characterization of novel ST1816 and ST128 variants in A. baumannii strains belonging to International clone II (GC2) with capsule types KL1:OCL8 and KL3:OCL1d from India. Sequence analysis revealed the presence of diverse virulome and resistome in these clinical strains, in addition to islands, prophages, and resistance genes. The oxacillinase blaOXA–23detected in the genomic island also highlighted the coexistence of blaOXA–66/blaOXA–98, blaADC73/blaADC–3, and blaTEM–1D in their mobile scaffolds, which is alarming. Together with these resistance-determining enzymes, multidrug efflux transporters also harbored substitutions, with increased expression in CRAB strains. The hotspot mutations in colistin resistance-conferring operons, PmrAB, LpxACD, and AdeRS, were additionally confirmed. Phenotype microarray analysis indicated that multidrug-resistant strains A. baumannii DR2 and A. baumannii AB067 preferred a range of antimicrobial compounds as their substrates relative to the other. To our knowledge, this is the first comprehensive report on the characterization of A. baumannii variants ST1816 and ST128, with different genetic makeup and genome organization. The occurrence of CRAB infections worldwide is a severe threat to available limited therapeutic options; hence, continued surveillance to monitor the emergence and dissemination of such novel ST variants in A. baumannii is imperative.

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