The role of the genetic elements bla oxa and IS Aba 1 in the Acinetobacter calcoaceticus-Acinetobacter baumannii complex in carbapenem resistance in the hospital setting

ABSTRACTThe frequency of the carbapenem-resistantAcinetobacter calcoaceticus-Acinetobacter baumannii(CRACB) complex increases annually in our hospitals. However, the types and prevalence of carbapenemases among isolates still remain unclear. In this study, we identified and collected 672 carbapenem-resistant isolates from a medical center in Northern Taiwan between April and December of 2010. There were 577 genospecies 2 (Acinetobacter baumannii), 79 genospecies 13TU, and 16 genospecies 3 isolates. The isolates had an acquiredblaOXA-24-like gene, which was confirmed by sequencing for the encoded OXA-72 carbapenemase, and were often associated with high-level carbapenem resistance. These CRACB complex isolates remained susceptible to colistin (100%). The genotyping of isolates was conducted using pulsed-field gel electrophoresis with ApaI digestion. In most clonally related groups, patients were from both branch hospitals. The results indicate that interhospital dissemination of clones occurred. This study provides updated data on the types and prevalence of the CRACB complex. In addition, it presents a warning on the emergence and spread of CRACB complex harboringblaOXA-24-like genes in northern Taiwan.

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Acinetobacter calcoaceticus–Acinetobacter baumannii complex species in clinical specimens in Singapore

Epidemiology and Infection ◽

10.1017/s0950268811001129 ◽

2011 ◽

Vol 140 (3) ◽

pp. 535-538 ◽

Cited By ~ 15

Author(s):

T. H. KOH ◽

T. T. TAN ◽

C. T. KHOO ◽

S. Y. NG ◽

T. Y. TAN ◽

...

Keyword(s):

Acinetobacter Baumannii ◽

Species Complex ◽

Carbapenem Resistance ◽

Acinetobacter Calcoaceticus ◽

Complex Species ◽

Clinical Specimens ◽

Carbapenem Resistant ◽

Acinetobacter Baumannii Complex ◽

Acinetobacter Pittii ◽

Resistant Strains

SUMMARYThis study was performed to determine the prevalence, distribution of specimen sources, and antimicrobial susceptibility of the Acinetobacter calcoaceticus–Acinetobacter baumannii (Acb) species complex in Singapore. One hundred and ninety-three non-replicate Acb species complex clinical isolates were collected from six hospitals over a 1-month period in 2006. Of these, 152 (78·7%) were identified as A. baumannii, 18 (9·3%) as ‘Acinetobacter pittii’ [genomic species (gen. sp.) 3], and 23 (11·9%) as ‘Acinetobacter nosocomialis’ (gen. sp. 13TU). Carbapenem resistance was highest in A. baumannii (72·4%), followed by A. pittii (38·9%), and A. nosocomialis (34·8%). Most carbapenem-resistant A. baumannii and A. nosocomialis possessed the blaOXA-23-like gene whereas carbapenem-resistant A. pittii possessed the blaOXA-58-like gene. Two imipenem-resistant strains (A. baumannii and A. pittii) had the blaIMP-like gene. Representatives of carbapenem-resistant A. baumannii were related to European clones I and II.

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Development of Loop-Mediated Isothermal Amplification Assay for Detection of Clinically Significant Members of Acinetobacter calcoaceticus–baumannii Complex and Associated Carbapenem Resistance

Frontiers in Molecular Biosciences ◽

10.3389/fmolb.2021.659256 ◽

2021 ◽

Vol 8 ◽

Author(s):

Amit Sharma ◽

Rajni Gaind

Keyword(s):

Acinetobacter Baumannii ◽

Lamp Assay ◽

Carbapenem Resistance ◽

Acinetobacter Calcoaceticus ◽

Isothermal Amplification ◽

Colony Count ◽

Dna Concentration ◽

Loop Mediated Isothermal Amplification ◽

Carbapenem Resistant ◽

Clinically Significant

Background:Acinetobacter calcoaceticus–baumannii (ACB) complex has emerged as an important nosocomial pathogen and is associated with life-threatening infections, especially among ICU patients, including neonates. Carbapenem resistance in Acinetobacter baumannii has emerged globally and is commonly mediated by blaOXA-23. Clinically significant infections with carbapenem-resistant Acinetobacter baumannii (CRAB) are a major concern since therapeutic options are limited and associated mortality is high. Early diagnosis of both the pathogen and resistance is important to initiate the optimal therapy and prevent selection of resistance. In the current study, a loop-mediated isothermal amplification (LAMP) assay was developed for rapid detection of the ACB complex and carbapenem resistance mediated by blaOXA-23.Methodology: Universal LAMP primers were designed for the detection of significant members of the ACB complex and carbapenem resistance targeting the ITS 16S–23S rRNA and blaOXA-23 gene respectively. The optimal conditions for the LAMP assay were standardized for each primer set using standard ATCC strains. The sensitivity of the LAMP assay was assessed based on the limit of detection (LOD) using different DNA concentrations and colony counts. The specificity of LAMP was determined using the non-ACB complex and non-Acinetobacter species. The results of the LAMP assay were compared with those of polymerase chain reaction (PCR).Results: The optimal temperature for the LAMP assay was 65°C, and the detection time varied with various primers designed. Using the ITS Ab1 primer, LODs of LAMP and PCR assays were 100 pg/μl and 1 ng/μl of DNA concentration and 104 cfu/ml and 108 cfu/ml of colony count, respectively. The LAMP assay was 10- and 104-fold more sensitive than PCR using DNA concentration and colony count, respectively. The LAMP assay was found to be specific for clinically important ACB complex species.Significance of the study: The LAMP assay can be applied for early detection of significant species of the ACB complex from clinical samples and their carbapenem-resistant variants. Depending on the emerging pathogen and locally prevalent resistance genes, the LAMP assay can be modified for detection of colonization or infection by various resistant bugs.

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Antimicrobial Susceptibility Pattern of Acinetobacter calcoaceticus-Acinetobacter baumannii Complex Isolated from Sputum in a Tertiary Care Hospital

Journal of Institute of Medicine ◽

10.3126/jiom.v41i3.37367 ◽

2019 ◽

Vol 41 (3) ◽

pp. 59-62

Author(s):

Jyotshna Sapkota ◽

Manisha Sharma ◽

Deepti Shrestha ◽

Beena Jha

Keyword(s):

Multidrug Resistance ◽

Acinetobacter Baumannii ◽

Tertiary Care ◽

Acinetobacter Calcoaceticus ◽

Clinical Microbiology Laboratory ◽

Care Hospital ◽

Sputum Specimen ◽

Susceptibility Pattern ◽

Acinetobacter Species ◽

Acinetobacter Baumannii Complex

Introduction Acinetobacter calcoaceticus-Acinetobacter baumanni (ACB) complex is one of the commonest cause of hospital acquired and ventilator associated pneumonia. Multidrug resistant Acinetobacter species have become a matter of huge concern. This study was done to find out the antibiotic susceptibility pattern of Acinetobacter calcoaceticus-Acinetobacter baumanii complex from sputum samples. MethodsThis descriptive cross-sectional study was carried out in Clinical Microbiology laboratory from July 2018 to Jan 2019 after ethical approval. Acinetobacter calcoaceticus-Acinetobacter baumannii complex was identified on the basis of its microscopy and morphological characteristics followed by biochemical tests. Antibiotic sensitivity test of isolated pathogens was done using Muller Hinton Agar by Kirby-Bauer method. ResultsOf the 384 culture positive sputum specimen, 76 (19.80%) were Acinetobacter calcoaceticus-Acinetobacter baumannii complex. Most of the isolates were resistant to commonly used antibiotics, 72.36% of the isolates were multidrug resistance and 3.95% isolates were resistant to tigecycline. ConclusionThis study provides valuable information regarding prevalence of Acinetobacter calcoaceticus-Acinetobacter baumannii complex from sputum specimen. The alarming number of Multidrug resistance isolates is worrisome finding. Antibiotics like Tigecycline and Colistin which is still sensitive to isolates should be cautiously used only in MDR cases.

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