Evaluation of phenotypic and genotypic markers for clinical strains of Acinetobacter baumannii (original) (raw)
Related papers
Correlation of six methods for typing nosocomial isolates of Acinetobacter baumannii
Journal of Medical Microbiology, 1995
A comparative study of biotyping, antimicrobial susceptibility, whole-cell protein analysis, plasmid analysis, pulsed-field gel electrophoresis of chromosomal DNA and polymerase chain reaction with arbitrary primers of Acinetobacter baumannii isolates from three large hospitals was performed to determine the best markers for epidemiological purposes. Ninety-two isolates were included : 38 belonged to a previously described outbreak and 54 were randomly selected from sporadic cases of infection. Biotyping, whole-cell protein and plasmid analysis were the least discriminatory methods, whereas antimicrobial susceptibility and polymerase chain reaction with arbitrary primers showed moderate discriminatory power. Typing based on pulsed-field gel electrophoresis of chromosomal DNA appeared to be the best discriminatory method (discrimination index of 0.9623). The addition of polymerase chain reaction with arbitrary primers or antimicrobial susceptibility to pulsed-field gel electrophoresis of chromosomal DNA did not further increase the discriminatory power.
Zentralblatt Fur Bakteriologie-international Journal of Medical Microbiology Virology Parasitology and Infectious Diseases, 1996
255 Acinetobacter strains, from clinical specimens of inpatients and outpatients, were identified phenotypically according to the new taxonomy proposed by Bouvet and Grimont. A. baumannii was the most frequent species (80.8%). This species underwent biotyping and serotyping according to the scheme of Bouvet and Grimont, and that of Traub, respectively. 81.2 % of samples belonged to biotypes 2, 6 and 9 with a predominance of biotype 2. 86.6% of the strains could be serotyped; 2 new serotypes were encountered. The new serotype 29, being the most frequently isolated, was related to biotype 2 (86.6%), whereas serotype 13 was related to biotype 6 (84.8%). These clones presented marked multiple resistance patterns and were widespread in different wards. No outbreak was reported during the period studied. These phenotypical methods proved to be useful in differentiating strains of A. baumannii and, if used together, they showed a high discriminatory power.
Molecular typing of Acinetobacter baumannii-Acinetobacter
Epidemiology and …, 1995
Ribotype, biotype and resistance phenotype were used to characterize 37 Acinetobacter baumannii-A. calcoaceticus complex isolates responsible for nosocomial infections in Buenos Aires. Nineteen isolates were recovered from endemic infections at 2 hospitals and 18 represent an intensive care unit outbreak that occurred in a third hospital. By ribotyping isolates were classified into five different clones of A. baumannii biotype 2, 3 of A. baumannii biotype 9, and 3 of Acinetobacter genospecies 13. Combination of the three epidemiological markers permitted categorization of 18 outbreak isolates into four probable strains: 2 A. baumannii biotype 2, named type I, and II, and 2 A. baumannii biotype 9. Type I (15 isolates) was the most prevalent strain at one hospital and was responsible for the outbreak. In conclusion, combined analysis of biotypes, resistance phenotypes, and ribotypes was an accurate approach for epidemiologic investigation of A. baumannii. Furthermore, ribotyping discriminated Acinetobacter genospecies 13 isolates which were phenotypically difficult to type.
Molecular Epidemiology of Nosocomial Acinetobacter baumannii Isolates
sciencepub.net
In view of the high rate and rapid spread of multidrug-resistant (MDR) Acinetobacter baumannii causing nosocomial infections especially in ICUs, this study was conducted to elucidate the antimicrobial susceptibility and the molecular epidemiology of the A. baumannii isolated from nosocomial infections in 3 ICUs in the El-Zaitoun Specialized Hospital, Cairo. During a 7-month study period, a total of 20 A. baumannii were isolated from nosocomial infections and environmental sources in the 3 ICUs. Susceptibility of the isolates to different antimicrobials was determined by the disk diffusion method. Molecular typing of all isolates was performed using the random amplified polymorphic DNA (RAPD)-PCR assay. A. baumannii were most frequently isolated from endotracheal aspirates (14), 4 strains from post-operative wound infection and 2 from environmental samples. All isolates were MDR and were totally resistant to imipenem, ampicillin/sulbactam, ceftazidime, ciprofloxacin, piperacillin/tazobactam and ceftriaxone. A high resistance rate was observed to amikacin and trimethoprim/sulfamethoxazole (90% each) gentamicin (85%) and doxycycline (75%). Molecular typing revealed circulation of 8 RAPD-fingerprints, of which fingerprint A accounted for 50% of A. baumannii strains including the 2 environmental isolates. Fingerprint B comprised 20% while the other isolates showed different RAPDfingerprints. In conclusion, there was an increase in the rate of MDR A. baumannii in the ICUs which necessitates the implementation of an appropriate antibiotic policy. The intrahospital spread of especially one RAPD fingerprint of A. baumannii and its isolation from environmental sources emphasize the need of strict adherence to infection control measures in hospitals as well as the value of molecular typing to investigate spread of infection.
Phenotypic and genetic relationship of Acinetobacter Baumannii isolates
Prilozi / Makedonska akademija na naukite i umetnostite, Oddelenie za biološki i medicinski nauki = Contributions / Macedonian Academy of Sciences and Arts, Section of Biological and Medical Sciences, 2011
Acinetobacter continues to rise. One of the main reasons is the emergence of multi-resistant strains, which cause outbreaks of infection involving several patients in a ward, in the intensive care unit and in different areas of the hospital. Many outbreaks of its infection or colonization in surgical, neonatal and burn intensive care units have been reported, but the epidemiology of these infections remains unclear. Aim: To investigate the relationship among the isolates of Acinetobacter baumannii, comparing some of their phenotypic and genetic features. Material and Methods: A total of 20 Acinetobacter baumanni isolates were included in the study. 12 strains of Acinetobacter baumannii were obtained within a week in July 2010, from neonates hospitalized at the paediatric intensive care unit and on the neonatal ward. Three strains were isolated from neonates at the paediatric intensive care unit three months ago. All the Acinetobacter baumannii strains were isolated from tracheal aspirates obtained from neonates with infection of the lower respiratory tract. Five additional Acinetobacter baumannii strains were included in the study as controls. They were isolated from wound swabs taken from adult patients with wound infection, hospitalized at the University Traumatology Clinic. Susceptibility of the bacterial strains to 13 different antimicrobial agents was determined by the disk diffusion method (Kirby-Bauer). Additional testing of the susceptibility was performed by the VITEK 2 system. RAPD-PCR fingerprinting was carried out using the following primer (5' GAAACAGCTATGACCATG-3'). Results: All A. baumannii isolates were multi-drug resistant. Antibiotic susceptibility-testing by the disk-diffusion method and automated VITEK 2 system showed 3 and 2 antimicrobial susceptibility patterns, respectively. RAPD-PCR assay of A. bau-Trajkovska-Dokic E, et al. Contributions, Sec. Biol. Med. Sci., XXXII/2 (2011), 157-168 mannii strains revealed two different RAPD-fingerprints. All the strains of A. baumannii isolated within a week in July 2010 from tracheal aspirates taken from neonates in the paediatric intensive care unit and neonates in the paediatric ward revealed the same RAPD-fingerprint, as well as 3 strains of A. baumannii isolated from tracheal aspirates taken from neonates in the paediatric intensive care unit three months ago. 5 strains of A. baumannii isolated from wound swabs of patients hospitalized at the Traumatology Clinic revealed a different RAPD-fingerprint. Conclusion: All the strains of A. baumannii isolated from neonates in the paediatric intensive care unit and paediatric ward were multi-drug resistant. Investigating the resistance patterns in multi-resistant isolates of Acinetobacter is a useful method which can predict the strain relationship. This method could be completed by at least one molecular method, such as the RAPD-PCR technique, which has shown itself to be a convenient and more reliable in interpreting the strain relationship of the A. baumannii isolates. Good infection control procedures, including phenotypic and molecular typing of A. baumannii isolates, are essential for preventing outbreaks of multi-drug resistant A. baumannii infections in our hospitals.
The International Arabic Journal of Antimicrobial Agents
A total of 12 Acinetobacter baumannii isolates have been recovered from hospitalized patients at two hospitals in Jordan over two different periods of time (2006 and 2008). Phenotypic and biochemical characterization with antibiotic susceptibility testing indicated that all isolates were belonging to A. baumannii. A high degree of conservation of both the 16S-23S rRNA gene intergenic spacer (ITS) length and the ITS sequence was observed among the isolates, and their identities were further confirmed by amplified ribosomal DNA gene restriction analysis (ARDRA). The application of ITS sequence-based identification and ARDRA provide promising tools for the elucidation of the clinical significance of genospecies identification of A. baumannii.
Infection, Genetics and Evolution, 2017
The multi-drug resistant (MDR) Acinetobacter baumannii as an important nosocomial pathogen has emerged a global health concern in recent years. In this study, we applied three easier, faster, and cost-effective methods including PCR-based open reading frames (ORFs) typing, sequence typing of blaOXA-51-like and RAPD-PCR method to rapid typing of A. baumannii strains. Taken together in the present study the results of ORFs typing, PCR-sequencing of blaOXA-51-like genes and MLST sequence typing revealed there was a high prevalence (62%, 35/57) of ST2 as international and successful clone which detected among clinical isolates of multi-drug resistant A. baumannii with ORF pattern B and blaOXA-66 gene. Only 7% (4/57) of MDR isolates belonged to ST1 with ORF pattern A and blaOXA-69 gene. Interestingly, we detected singleton ST513 (32%, 18/57) that encoded blaOXA-90 and showed the ORF pattern H as previously isolated in Middle East. Moreover, our data showed RAPD-PCR method can detect divergent strains of the STs. The Cl-1, Cl-2, Cl-3, Cl-4, Cl-10, Cl-11, Cl-12, Cl-13 and Cl-14 belonged to ST2. While the Cl-6, Cl-7, Cl-8 and Cl-9 belonged to ST513. Only Cl-5 belonged to ST1. It seems that the combination of these methods have more discriminatory than any method separately and could be effectively applied to rapid detection of the clonal complex (CC) of A. baumannii strains without performing of MLST or PFGE.
Journal of the Chinese Medical Association, 2016
Background: Acinetobacter baumannii has become one of the most serious causative agents of nosocomial infections due to its significant ability to survive on hospital surfaces. It is mainly an emerging opportunistic pathogen infecting patients in intensive care units. This study was aimed to identify the clinical isolates of A. baumannii and to investigate their heterogeneity using polymerase chain reaction (PCR)-based typing methods. Methods: A total of 197 nonduplicate isolates recovered from a wide range of clinical samples were subjected to conventional cultural and biochemical tests. For those isolates that were preliminary identified as A. baumannii, rpoB-based PCR with subsequent restriction fragment length polymorphism (RFLP) using two restriction enzymes (TagI and HaeIII) was performed to investigate the genetic diversity of the strains and their presumptive relationships with different clinical presentation of the disease caused by this pathogen. Results: In total, 50 isolates (25.4%) were identified as A. baumannii using conventional phenotypic methods with subsequent confirmation by rpoB sequencing. RFLP analysis demonstrated five different restriction enzyme patterns, designated as AeE clusters. Most A. baumannii isolates were categorized under Cluster A (32%). We found no significant relationship between clinical presentation and the clustering of the isolates. Conclusion: This study showed that the rpoB region possesses high discriminatory power to identify the isolates to the species level. This marker showed high interspecies variability that might be useful for strain typing. The results also suggest the possibility of the existence of a predominant clone of A. baumannii among infected patients in Iran.
BMC Microbiology
Background: Multi-drug resistant (MDR) Acinetobacter baumannii is one of the most important causes of nosocomial infections. The purpose of this study was to identify antibiotic resistance patterns, biofilm formation and the clonal relationship of clinical and environmental isolates of A. baumannii by Pulsed Field Gel Electrophoresis method. Forty-three clinical and 26 environmental isolates of the MDR A. baumannii were collected and recognized via API 20NE. Antibiotic resistance of the isolates was assessed by the disk diffusion method, and the biofilm formation test was done by the microtiter plate method. Pulsed Field Gel Electrophoresis (PFGE) was used to assess the genomic features of the bacterial isolates. Results: The resistance rate of clinical and environmental isolates against antibiotics were from 95 to 100%. The difference in antibiotic resistance rates between clinical and environmental isolates was not statistically significant (p > 0.05). Biofilm production capabilities revealed that 31 (44.9%), and 30 (43.5%) isolates had strong and moderate biofilm producer activity, respectively. PFGE typing exhibited eight different clusters (A, B, C, D, E, F, G, and H) with two significant clusters included A and G with 21 (30.4%) and 16 (23.2%) members respectively, which comprises up to 53.6% of all isolates. There was no relationship between biofilm formation and antibiotic resistance patterns with PFGE pulsotypes. Conclusions: The results show that there is a close relationship between environmental and clinical isolates of A. baumannii. Cross-contamination is also very important that occurs through daily clinical activities between environmental and clinical isolates. Therefore, in order to reduce the clonal contamination of MDR A. baumannii environmental and clinical isolates, it is necessary to use strict infection control strategies.
Plant Archives, 2019
Phenotypic and genotypic detection of Acinetobacter baumannii is the commonly used methods for identification. This study evaluated the accuracy of these two detection methods. A. baumannii were identified based on Gram staining, API 20 EN, Vitek-2 and Polymerase chain reaction (PCR) amplification of organism specific 16S rRNA gene and bla OXA-51 like gene. In the present study, 100 clinical specimens were isolate from different sources, including (Sputum, Wounds, Burns, UTI and blood), 61 samples were correctly identified as A. baumannii according to API 20 EN, Vitek-2, whereas the PCR result showed that 45 sample of the 61 were positive by using 16S rRNA gene and bla OXA-51 like gene detection.