Baumanii Isolates Research Articles

MOLECULAR ANALYSIS OF THE MCR-1 GENE IN PSEUDOMONAS AERUGINOSA AND ACINETOBACTER BAUMANII STRAINS

Objective: The emergence of antibiotic resistance in Pseudomonas aeruginosa and Acinetobacter baumanii isolates poses serious risks to public health. Our study aimed to investigate the presence of colistin resistance and mcr-1 gene positivity in these isolates. Material and Method: Culture, biochemical tests, antibiotic susceptibility tests, and molecular tests were used to isolate and identify P. aeruginosa and A. baumanii strains. Result and Discussion: A sum of 156 clinical isolates of Pseudomonas aeruginosa (n = 89) and Acinetobacter baumannii (n = 67) were obtained using the 550 clinical samples collected in one year from the largest hospital in Van, Turkey. The results of antibiotic susceptibility tests showed that approximately 82.8% of P. aeruginosa and 94.6% of A. baumannii strains were multidrug-resistant (MDR). Colistin resistance was detected in 11.23% (10/89) of P. aeruginosa isolates and 11.94% (8/67) of A. baumannii isolates using agar dilution and microdilution methods. Out of the 18 colistin-resistant isolates, the mcr-1 gene was detected in three P. aeruginosa and two A. baumannii strains. The detection of plasmid-mediated colistin resistance in P. aeruginosa and A. baumannii is of great concern due to the high potential for colistin resistance to spread in clinical settings. Understanding the unique circumstances of worldwide colistin resistance can be facilitated by promoting the creation of quick processes for identifying colistin resistance profiles and putting them into practice in hospital laboratories. Colistin and carbapenem treatment are two effective ways to treat emerging resistant super-microbes and slow down the emergence of resistance.

Efflux pumps encoding genes (adeA and adeS) in relation to antibiotic resistance pattern in Acinetobacter baumannii strains isolated from Benha university hospital

Background Acinetobacter baumannii become a growing problem in hospitals as a predominant multidrug-resistant (MDR). This resistance capacity is generated by various mechanisms including efflux pumps that can direct antibiotics outwards and prevent antibiotics from affecting the bacteria. Methods Clinical samples were cultured on blood agar and MacConkey agar medium, identified by Gram stain and biochemical reactions, and then identified to the species level by Vitek2 automated system. The adeA and adeS genes among isolated strains were detected by conventional PCR. This study included 50 A. baumannii strains to assess the antibiotic resistance pattern of A. baumannii. Results A. baumannii strains were fully resistant to Piperacillin (100%) and lowest resistance to Imipenem (54%) was observed. Out of 50 isolates, 41 (82%) of A. baumanii isolates had adeA gene and 32 (64%) had adeS gene. The clinical strains that had adeA gene and adeS gene showed significantly higher resistance to Ciprofloxacin (92.7%) and (100%), respectively. Additionally, borderline significant differences were reported regarding Gentamycin (P = 0.065), Ceftazidime (P = 0.08), and Meropenem (P = 0.08), with the resistance being higher in the adeA positive group. Conclusion Efflux pumps genes (adeA, adeS) played a key role in antibiotic resistance of A. baumanii.

The antibacterial effect mechanisms of Laurus nobilis extracts on carbapenem-resistant Acinetobacter baumanii isolates

Carbapenem-resistant Acinetobacter baumannii infections are becoming increasingly difficult to treat. Thus, this paper focused on identification of carbapenemase genes in carbapenem-resistant A. baumanii isolates, determining the antibacterial activities of Laurus nobilis L. leaves extracts in both carbapenem-sensitive and resistant strains, and comparing MIC values in strains with various carbapenemase genotypes. Besides, the components of Laurus nobilis extracts and the theoretical calculation of the antibacterial effect mechanisms of Laurus nobilis extracts on A. baumanii isolates were investigated. The MIC value of Laurus nobilis extracts was found to be 250 μg/ml in A. baumanii isolates carrying one or two carbepenemase genes, while the MIC value was found to be 500 μg/ml in strains carrying three or more carbapenemase genes. The extracts of Laurus nobilis had the highest concentration of rutin, followed by ferulic acid. The interaction of the major component of the extract, rutin, with OXA-51 was explored by molecular docking to demonstrate its binding potential. Its interaction was then compared to the interaction of a standard drug (doripenem). The binding potential of rutin was found to be slightly higher than that of doripenem that reflected the limited activity of the extract on the carbapenem-resistant strains. Consequently, new treatment drugs have needed to limit the spread of carbapenem-resistant A. baumannii.

Antibiogram of Acinetobacter baumannii isolated from Intensive Care Unit at Prof. dr. I.G.N.G. Ngoerah Hospital in 2020-2022

Background: Acinetobacter baumannii infection is a severe problem since it tends to be multi-resistant to many antibiotics. This study aimed to determine the prevalence of A. baumannii isolated from blood, urine, and sputum cultures and their antibiotic resistance patterns. Methods: Data of A. baumanii isolated from clinical specimens of Intensive Care Unit (ICU) wards patients were collected retrospectively from laboratory records in the Clinical Microbiology Department of Prof. Dr. I. G. N. G. Ngoerah General Hospital during 2020-2022. Identification and antimicrobial susceptibility tests were conducted using the Vitek-2 Compact system (bioMérieux, France). Isolates resistant to ≥ 3 antibiotic classes were categorized as multidrug-resistant (MDR) A. baumanii. Results: A. baumanii collected from sputum, blood, and urine in Intensive Care Unit (ICU) wards were 63%, 13%, and 7.5% from 2020 until 2022. Most A. baumanii isolates in 2020, 2021, and 2022 were susceptible to Amikacin, which was 75%, 78%, and 76%, respectively. Furthermore, the isolates that were susceptible to Trimethoprim/Sulfamethoxazole were 66%, 81%, and 72%, followed by Tigecycline, 80%, 61%, and 56% respectively. A. baumanii, however, showed low sensitivity to Meropenem even though susceptibility is getting higher each year. Almost all the isolates were resistant to ceftriaxone. Conclusions: Acinetobacter baumannii isolates isolated during 2020-2022 showed high resistance to penicillin, cephalosporin and fluoroquinolones. Although A. baumanii was resistant to carbapenem, its susceptibility tends to increase throughout the 3 years of this study. These data could be considered for empirical therapy of A. baumanii infections.

Bacterial ecology of sepsis in febrile neutropenics on hematology-oncology services

Introduction: Febrile neutropenia is a hematologic emergency that develops following treatment of hematologic malignancies. It exposes patients to the risk of sepsis, which is a major cause of morbidity and mortality. Currently, coagulase-negative staphylococci are the most common bloodborne isolates while enterobacteria are isolated less frequently. The objective of our study is to determine the epidemiological, bacteriological and antibiotic susceptibility profile of strains isolated from blood cultures collected from febrile neutropenic patients at Hassan II University Hospital, Fez. Materials and methods: This is a prospective study, over a period of 4 years (January 2019 - December 2022) including 83 patients with bacteremia hospitalized in the department of hemato-oncology. Identification and detection of antibiotic resistance was performed according to conventional bacteriology methods and CA-SFM/EUCAST recommendations. Results: Among 524 blood cultures received, we diagnosed 83 cases of bacteremia. The average age of the patients was 55 years. The average age of the patients was 55 years. The predominance of women was noted, with a sex ratio of 0.88. The majority of the episodes, 94.87%, occurred in patients followed for a neoplastic pathology. Hematological malignancies were the most responsible with a rate of 61.54% against 33.33% of solid tumors. Gram-positive bacteria represent 56.6%, and 43.4% of Gram-negative bacteria. The proportions of the different bacterial classes (BGN / CG+) have remained stable over the last 4 years, Staphylococcus epidermidis was the most frequent isolated Gram-positive bacteria 24.1℅(n=29) then Staphylococcus aureus 24.6% (n=18), followed by Gram-negative bacteria of enterobacteria type especially Escherichia coli which was the most frequently isolated pathogen (16.86%), followed by Klebsiella pneumoniae (10.84℅) and non-fermenting Gram-negative bacteria such as Pseudomonas aeruginosa (8.4) and Acinetobacter baumanii (6℅). Bacteria of clinical interest have shown increasingly worrisome levels of beta-lactam resistance, with extended-spectrum beta-lactamase (ESBL)-producing strains of Klebsiella pneumoniae accounting for 4, 8% with only one case of carbapenemase, meticillin-resistant Staphylococcus aureus was 3.61% while no imipenem-resistant Pseudomonas aeruginosa or vancomycin-resistant enterococci were found. While Acinetobacter baumanii isolates (n=5) showed increased resistance to the majority of antibiotics tested, especially to imipenem which was 100%. Discussion and conclusion: Gram-positive bacteremia of the genus coagulase-negative staphylococcus is the most common type of infection in febrile neutropenias showing an increasingly resistant profile to first-line antibiotics. However, Gram-negative infections have shown decreased susceptibility compared to previous years. A regular study of the bacterial ecology of blood culture isolates and a determination of antibiotic susceptibility are necessary to optimize the probabilistic antibiotic therapy of bacteremia.

Antimicrobial susceptibility pattern of an emerging multidrug resistant <em>Acinetobacter baumannii </em>from intensive care units of a tertiary care hospital

Introduction: Acinetobacter baumannii is one of the most challenging gram negative, lactose non-lactose fermenting bacilli with ability to cause nosocomial infections and develop resistance to many classes of antibiotics. Multidrug-resistant (MDR) A. baumannii is a well known agent causing life-threatening infections with limited therapeutic options. In recent years, the numbers of reported carbapenem-resistant Acinetobacter spp. are increasing, which has further narrowed the treatment options and emerging as extensively drug resistant (XDR) strain. There are only a few effective drugs such as colistin, polymyxin B, and tigecycline. But given the side effects and cost effectiveness, treatment of resistant nosocomial infections by A. baumanii is the biggest challenge for clinicians and policy makers all over the world.Aim:1. To know the antibiotic susceptibility pattern of Acinetobacter baumnii2. To know the prevalence of multidrug resistant Acinetobacter baumanii in critical areas of our tertiary care centre.Methodology: Clinical samples from both critical and non critical areas were processed routinely. Only non lactose fermenting colonies were included for the study and Acinetobacter baumanii isolates were identified using standard culture method and antibiotic susceptibility testing done by disk diffusion method.Results: Of 308 NLFs, 160 were Acinetobacter baumanii. 106 (66.25%) samples were from ICU and 54 (33.75%) from non critical areas. Commonest sample was endotracheal secretion 72(45%) followed by blood 38(23.75) and others. 70% of our isolates were resistant to Aminoglycosides. Among Fluoroquinolones, maximum resistance was shown for Ciprofloxacin. 59% of the isolates were resistant to Piperacillin-tazobactum and their resistance to Cephalosporins ranged from 60-80%. 42 (39.62% of our isolates were Multidrug resistant (MDR) and 19 (17.92%) were extensively drug resistant (XDR).Conclusion: Multidrug resistant and extensively drug resistant strains of Acinetobacter baumanii are on the rise and slowly getting established in our healthcare set up especially the critical areas. Treatment options are very few and limited. Thus leaving us with call to take stringent measures to stop the inadvertent use of antibiotics and to review our infection control policies.

Study the effect of Indian premium (Saussurea costus) extract and sesame oil on the sensitivity of local Acinetobacter baumannii isolates causing infection

The current investigation was intended to assess the viability of sesame oil got from Heet city and Indian premium (saussurea costus) affectability testing against Acinetobacter baumanii isolates detached from disease destination like urine, sputum, C.S.F, wound swab, and burn swab. The results indicated that sesame oil activated the gentamycin antibiotic activity from 3.08 mm to 14.7500 mm and also the Indian premium made the same thing the activation was from 5.4167 mm to 9.3333 mm. while the addition of sesame oil to Imipenem anti biotic there was inhibition in the activity of Imipenem from 21.33 mm to 20.083mm and when we added the Indian premium there was activation to the Imipenem antibiotic was from 22.1667 mm to 23.4167mm. Finally the results of cefotaxime after adding the sesame oil we noticed that there is decrease in the activity of cefotaxime from 3.500 mm to 1.000 mm and we also noticed that the addition of Indian premium to the antibiotic there was decrease in the activity from 3.9167 mm to 3.333 mm.
 Therefore ower explanation that there is activation to some antibiotics there is also inhibition to the other by adding different plant extract.

Molecular detection of blaOXA-23 gene and blaOXA-51 gene in carbapenem resistant strains of Acinetobacter baumannii in patients with ventilator associated pneumonia at tertiary care hospitals.

To evaluate carbapenem resistance and to detect blaOXA-23 and blaOXA-51 genes in carbapenem-resistant Acinetobacter baumanii isolates recovered from patients having pneumonia secondary to ventilation. The cross-sectional study was conducted from July 2017 to June 2018 at the Department of Microbiology, University of Health Sciences, Lahore, Pakistan, and comprised endotracheal aspirates / tracheobroncheal lavage samples from patients irrespective of age and gender who developed pneumonia after being on the ventilator for 48 hrs at the Combined Military Hospital, and Jinnah Hospital, Lahore. The samples were inoculated on MacConkey and blood agar and aerobically incubated at a temperature of 370C for 18-24 hours. The isolated organisms were further assessed by standard morphological, cultural and biochemical profile. Antibiotic susceptibility was done by Kirby-Bauer disc diffusion method. Carbapenem-resistant Acinetobacter baumannii were checked for carbapenemase production using Modified Hodge Test. Conventional polymerase chain reaction and agarose gel electrophoresis were performed to detect blaOXA-23 and blaOXA-51 genes. Data was analysed using SPSS 17. Out of 157 samples, 92(58.6%) yielded growth of bacteria, and, among them, 39(42.4%) were identified as Acinetobacter baumannii. All (100%) Acinetobacter baumannii cases showed resistance to carbapenem, were producing carbapenemase enzyme, and were positive for blaOXA-51 gene. The blaOXA-23 gene was amplified in 38(97.4%) isolates. BlaOXA-23 gene appeared to be the major cause of carbapenem resistance.

Molecular characterization and antibiotic resistance pattern of isolated Acinetobacter baumannii in Iran

In this study, the prevalence of efflux pump genes (AdeABC) and genetic association of MDR A. baumanii isolated from intensive care units were investigated. Detection of A. baumanii was performed using species-specific PCR. Disc-diffusion antibiotic susceptibility tests of isolated strains and amplification of AdeABC genes (adeA, adeB, adeC, and adeM) were performed. Isolates were also subjected to the Repetitive Extragenic Palindromic-PCR (rep-PCR) to identify isolates clonality. The highest number of resistant A. baumanii isolates was observed in response to cephalexin, tetracycline, and cefixime (over 80% of isolates). A. baumanii isolates had the highest sensitivity in response to imipenem and amikacin (~ 50% of isolates). The distribution of adeA, adeB, adeM, and adeC in isolates were as follow; 186, 165, 172, and 117 isolates. A. baumanii was observed at an alarming level in this study (183, 93.84%). Based on rep-PCR, remarkable interspecific diversity was observed among isolates.

Bir Eğitim ve Araştırma Hastanesinde Yatan Hastalarda Acinetobacter baumannii İnfeksiyonları ve Antibiyotik Direnci: Altı Yıllık Analiz

Introduction: Acinetobacter baumanii causes difficulties in the treatment of nosocomial infections due to increasing resistance worldwide. With an increase in resistant infections, the use of colistin has come to the fore. We aimed to investigate the antimicrobial resistance profile of A. baumanii strains isolated from clinical specimens as hospital-acquired colonizations and infection agents and to evaluate the clinical and microbiologic responses and adverse effects of antibiotic regimens used in patients who were isolated because of having infectious agents. Materials and Methods: A retrospective descriptive study of 326 adult patients with nosocomial A. baumannii colonizations and infections was conducted between January 2012 and December 2017 in Niğde Education and Research Hospital. In addition, a total of 212 adult patients who received at least 72 hours of antimicrobial therapy were evaluated. Standard and automated methods were used to identify isolated strains and antibiotic susceptibility. The antimicrobial susceptibility profile change over the 6-year period was evaluated. Adverse effects, and clinical and microbiologic response were evaluated in patients receiving antimicrobial therapy. Analysis of the variables was performed using SPSS 22.0 (IBM Corporation, Armonk, New York, United States). Results: When antimicrobial resistance rates were examined, it was seen that imipenem (99.7%), ampicillin sulbactam (81.6%), cefoperazone sulbactam (60.3%), netilmicin (89.4%), tobramycin (88.4%), gentamicin (83.1%), amikacin (91.6%) and tigecycline (33.7%) had resistance rates; colistin resistance was not detected in the isolates. Resistance rate to other antibiotic groups was 100%. The resistance rates of ampicillin sulbactam, cefoperazone sulbactam, gentamicin, amikacin, and tigecycline were found to be statistically significant (p< 0.05). There were no significant differences in terms of nephrotoxicity, and clinical and microbiologic response among patients in whom colistin was used in combination with carbapenem, ampicillin/sulbactam, cefoperazone/sulbactam, and tigecycline (p> 0.05). Conclusion: In accordance with the global data, antimicrobial resistance rate in A. baumanii isolates was found to be high in our study. Treatment regimens in which colistin is used with other antimicrobial agents have no superiority in terms of efficacy and adverse effects. There is a clear need for new and effective antimicrobial agents in the treatment of resistant A. baumanii infections.

Antimicrobial susceptibility patterns of Acinetobacter baumanii isolates from ICU and non-ICU wards

Introduction: Acinetobacter baumanii is the most common agent of hospital-acquired infection with the increasing fatality rate due to multidrug-resistant (MDR) strain infection. The magnitude of the problem in Indonesia is unknown. Here, we provide data regarding susceptibility pattern of A. baumanii isolated from a tertiary referral hospital in Bali, Indonesia between 2012 and 2014. Methods: Data were collected retrospectively from culture-based records in the Clinical Microbiology department, Sanglah General Hospital during 2012-2014. A. baumanii was isolated from clinical specimens. Identification and antimicrobial susceptibility test were conducted using micro-dilution method (Vitek-2 Compact system). Isolates that resistant to ≥ 3 antibiotic classes were categorized as multi-drug resistant (MDR) A. baumanii. Results: A. baumanii collected from sputum in intensive care unit (ICU) wards were 7.9%, 11.1%, and 7.0%, while the isolates from sputum in non-ICU wards were 13.1%, 15.6%, and 19.9% in 2012, 2013, and 2014, respectively. There was a reduced susceptibility of A. baumanii to ciprofloxacin, levofloxacin, ceftazidime, aztreonam, imipenem, ampicillin-sulbactam, and piperacillin-tazobactam in ICU ward. Meanwhile, the susceptibility of A. baumanii to Cotrimoxazole remained high in both ICU and non-ICU ward. MDR A. baumanii is found to be resistant to fluoroquinolones, cephalosporins, aztreonam, aminoglycosides, beta-lactamase inhibitors, and carbapenem. Data were analyzed and presented in a descriptive manner. Conclusion: Three years surveillance showed that the susceptibility of A. baumanii to most common antibiotics was decreasing. MDR A. baumanii was found to be resistant to all classes of common antibiotics mostly from ICU ward isolates.

Wound infections after orthopedic surgery: distribution and resistance situations of microorganisms

Aim: Wound infections are one of the important complications of orthopedic surgery. In this study it was aimed to determine the causative microorganisms, isolation regions and antimicrobial resistance states in the postoperative surgical wound infections. Material and Method: Between 01.09.2015 - 30.09.2017, postoperative surgical wound infections of patients who applied to our orhopedia and traumatology clinic were retrospectively evaluated and 57 microorganisms were isolated. For identification of species of isolated microorganisms, conventional methods and VITEK 2 Compact® (Biomerieux, France) automated bacterial identification system were used. For antibiotic susceptibility testing VITEK2 Compact® (Biomerieux, France) automated susceptibility system were used. Results: A total of 57 microorganisms isolated, 32 (56%) were gram negative and 25 (44%) gram positive bacteria. The most frequently isolated bacteria were S. aureus 22 (38.5%) and others in order E. coli 15 (26.3%), E. cloacea 7 (12.3%), A. baumanii 3 (5.3%), P. aeroginosa 3(5.3%) E. aerogenes 1 (1.8%), E. faecalis 1 (1.8%) , E. americana 1 (1.8%) K. pneumonia 2 (3.5%), S. haemolyticus 2 (1.8%) species. With 23 isolates the hip was the orthopedic region in which the most microorganism was isolated. Antibiotic resistance rates of S. aureus isolates are very low compared to S. heamolyticus isolates. A. baumanii isolates were the most resistant in gram negatives. Conclusion: Cleaning and a sepsis of the hands and incision area are very important in preventing postoperative infections. For successful treatment of these infections, infectious agents and their in vitro antibiotic susceptibility should be known. Thus, with the use of rational antibiotics the success of treatment will increase the spread of resistant hospital infections will be prevented and the costs of treatment will be reduced.

Molecular characterization and genetic relatedness of clinically Acinetobacter baumanii isolates conferring increased resistance to the first and second generations of tetracyclines in Iran

BackgroundThe increasing resistance of Acinetobacter baumannii to antibiotics has recently been regarded as a notable therapeutic difficulty. Evaluating resistance rates of some A. baumannii isolates to tetracyclines had an impact on understanding the antibiotic resistance dissemination. By comparing genetic characteristics and relatedness of A. baumannii isolates, we are able to determine the transition dynamics of outbreak isolates.MethodsA total of 72 non-duplicate isolates of A. baumannii were recovered in 2011 and 2015 and minimum inhibitory concentration (MIC) range distribution of the isolates to tetracyclines was performed by broth micro dilution (BMD) assay, and to determine the lineage relatedness of the outbreak isolates repetitive extragenic palindromic element based on polymerase chain reaction (rep-PCR) and international clonal (ICs) investigations were performed.ResultsResistance rates to tetracycline, doxycycline and minocycline in 2011 were 73, 2 and 0%, while these rates in 2015 increased up to 90, 84 and 52%, respectively. The tetB existed in 100% of all the isolates of both years. tetA was not found in any of the isolates. According to the rep-PCR assays, up to 83% of all isolates clustered distinctly and only 6% of isolates had a common root. The percentage rates of IC1 decreased from 42% in 2011 to 22% in 2015, while those of IC2 increased from 28 to 36%, from 2011 to 2015.ConclusionsOur data showed that resistance to the first and second generations of tetracyclines is on the rise and the clonal transition dynamics of isolates are in progress in our hospital.

Antimicrobial Susceptibility Pattern and Prevalence of Extended-Spectrum β-Lactamase Genotypes among Clinical Isolates of Acinetobacter baumanii in Tabriz, North-West of Iran

Background: Multidrug resistant (MDR) Acinetobacter baumanii strains have emerged as novel nosocomial pathogens threatening patients’ lives, especially in intensive-care units (ICU). Various types of extended-spectrum β-lactamases (ESBLs) are involved in conferring resistance to β-lactam antibiotics, making their genotypic characterization an essential prerequisite to take proper preventative measures. Objectives: The aim of this study was to determine the antimicrobial susceptibility and prevalence of blaTEM, blaSHV, blaCTX-M, blaOXA-2, and blaOXA-10 genes among A. baumanii isolates obtained from patients in Tabriz city, North-west Iran. Methods: The clinical isolates of A. baumanii were collected from patients hospitalized in the Imam Reza hospital of Tabriz. Antimicrobial susceptibility patterns were determined by the disk diffusion method. The frequency of different ESBLS resistance genes were determined by PCR. Results: Antimicrobial susceptibility testing through the disk diffusion method revealed that the lowest resistance rates were against polymyxin B (16%), colistin (23%), and rifampin (27%); whereas the highest resistance rate was observed against ticarcillin (100%), cefixime (100%), and ceftizoxim (100%). Screening by double disk synergy test showed that 60% of the isolates were ESBL producers. PCR technique on ESBL-positive isolates determined blaSHV gene as the most prevalent (31.6%) and blaOXA-10 as the least prevalent (8.3%) among the studied resistance genes. Conclusions: The high prevalence of resistance genes supported the essential role of ESBLs in antibiotic resistance of A. baumanii.

Analysis of clinical and microbiological data on Acinetobacter baumannii strains assist the preauthorization of antibiotics at the patient level for an effective antibiotic stewardship program.

Drug resistant Acinetobacter baumannii (A. baumannii) poses serious treatment challenges and is on the rise worldwide. The Infectious Diseases Society of America/Society for Healthcare Epidemiology of America recommends preauthorization of antibiotics to ensure successful antibiotic stewardship programs (ASWPs). This study estimates and analyzes the microbiological and clinical characteristics of A. baumanii strains with differentiating criteria for sepsis versus colonization, in order to support preauthorization and assist ASWPs at the patient level. A retrospective observational study was performed from 2008 to 2014. The clinical and microbiological characteristics of A. baumannii strains were correlated to assess pathogenic status and antibiotic resistance patterns. A flow chart was produced to differentiate between sepsis and colonization amongst patient groups. A. baumannii was cultured in 2656 cases, with a prevalence of 0.9-2.4% during 7 years study periods. There was a statistically significant difference between the sepsis and colonization groups (P=0.02). Sepsis accounted for 37-51% of A. baumanii isolates and colonisation for 49-63% (P=<0.01). Multidrug resistant (MDR), extensive drug resistant (XDR) and pandrug resistant (PDR) A. baumannii was detected in 53-60%, 1-19% and 1% of cultures in the sepsis group, and 75%, 8-23% and 1% in the colonized group. There was a high percentage of polymicrobial infection in the sepsis group and pure growth was not always significant for sepsis. Cases of MDR and XDR A. baumannii increased over the seven-year study, while PDR strains emerged. For a successful ASWP, both clinical and microbiological information should be interpreted when establishing preauthorization/decision to treat.

English

Multiple drug-resistant strains of Acinetobacter have become common in hospitals worldwide. The problem becomes more acute with existence of hidden Carbapanemase-resistance genes that co-exist with other resistance determinants. Based on this, this research aims to determine the occurrence and co-existence of OXA-type carbapenemases and 16S rRNA methylase gene among clinical isolates of A. baumannii in a Jilin hospital, China. Between January 2012 to December 2013, 32 A. baumanii non-repetitive strains were isolated from nosocomial clinical specimens. Susceptibility to antibiotics was determined by the standard microdilution method and phenotypic testing was used to detect the presence of carbapenemases. PCR was performed using specific primers for detection of class D carbapenemase genes and 16S rRNA methylase gene. Results revealed that all imipinem resistant A. baumannii isolates were resistant to all antibiotics tested except polymycin E. The isolates harbored different Oxacillin Type Carbapenemases, that is, 62.5% of the isolates harbored OXA-51, 37.5% OXA-23, 18.8% OXA-58, 3.1% OXA-24 and 59.4% harbored 16S rRNA methylase gene. Of the 19 isolates harboring 16S rRNA methylase gene, 47.4% coexisted with at least one oxacillinase gene while 40.6% of the 32 A. baumanii isolates harbored more than one different oxacillinase gene. At least one oxacillinase gene was detected in 28.1% of the isolates that were phenotypically negative for carbapenemase production. The current study therefore shows co-existence of resistance determinant genes and existence of hidden genes responsible for resistance. Multiple mechanisms are likely to work in synergism to produce this phenotype. Key words: A. baumannii, metallo-&beta;-lactamases, nosocomial infection.

Detection of New Delhi Metallo Beta Lactamase-1 (BlaNDM-1) Gene among a Group of Carbapenem Resistant Acinetobacter Baumannii Isolates

Background: A variety of carbapenemases have been reported in Acinetobacter species. One of the most clinically significant carbapenemases is the recently described New Delhi metallo- β -lactamase (bla NDM-1 ). Objective: This study aimed to determine the presence of bla NDM-1 gene among a group of carbapenem resistant Acinetobacter baumanii isolates from hospitalized patients. Methodology: Thirty carbapenem resistant Acinetobacter baumanii isolates from different sites of nosocomial infections from ICU patients were included in the study. They were tested by real time PCR for the presence of bla NDM-1 gene. Results: None of the tested isolates in this study was positive for this gene. Conclusion: Further studies on larger numbers should be done to confirm or rule out the role of the bla NDM-1 gene in carbapenem resistance of Acinetobacter baumanii in nosocomial infections.

Genetic relatedness of clinical and environmental Acinetobacter baumanii isolates from an intensive care unit outbreak

Determination of microbial genetic relatedness is important for improving efficiency of infection control measures during hospital outbreaks. This study aimed to analyze the clonal relationships of clinical and environmental Acinetobacter baumannii strains isolated during an outbreak in the intensive care unit (ICU) of a secondary care hospital in Saudi Arabia. Twelve clinical and fourteen environmental A. baumannii isolates identified during an outbreak in February 2013 in the 14-bed adult intensive care unit of a tertiary care hospital in Riyadh, Saudi Arabia, were studied. Bacterial identification and antimicrobial susceptibility testing were carried out using Microscan Walkaway 96 automated system. Determination of clonal diversity was investigated by repetitive-sequence-based polymerase chain reaction (rep-PCR) with the semi-automated DiversiLab system. The majority of the clinical isolates were from endotracheal tube aspirates (n = 9), one from a wound swab and two were from urine and sputum, respectively. Environmental isolates were from bed railings (n = 10) and with one each from curtain, stethoscope, computer mouse and telephone. Isolates were categorized into 6 clusters (Groups 1-6). Most of the isolates were associated with two clusters namely Groups 2 (n = 11) and 3 (n = 9). All isolates were multidrug resistant showing resistance to three or more classes of antibiotics. One clinical strain from Cluster 3 was resistant to colistin (MIC > 4ug/ml). This outbreak was caused by two clonal groups of multidrug resistant A. baumannii. The presence of multiple environmental clones was suggestive of environmental source dissemination via healthcare workers within the ICU.

Antimicrobial Susceptibility of Multidrug-Resistant &amp;lt;i&amp;gt;Acinetobacter baumanii&amp;lt;/i&amp;gt; in a Teaching Hospital: A Two-Year Observation

Multidrug-resistant (MDR) Acinetobacter baumanii (A. baumanii) caused hospital acquired infection, typically in critical-ill patients with medical devices. This is a retrospective descriptive study on epidemiology and microbiology data to determine the antimicrobial susceptibility pattern of MDR-Acinetobacter baumanii isolates from a teaching hospital in Tangerang, Indonesia from Januari 2013 to December 2014. A total of 84 A. baumanii were collected. Patients suffering from respiratory tract infection had the highest number (41.7%) of A. baumanii isolate. There were 39 (46.6%) patients admitted in critical care. A. baumanii isolates in this study mostly were multidrug-resistant organisms with low susceptibility level to 11 antibiotic tested, 44% - 69% in 2013 and 26% - 67% in 2014. A high susceptibility level was observed to amikacin (80% and 79% in 2013, 2014 consecutively) and trimethoprim-sulfamethoxazole (73% and 72% in 2013, 2014 consecutively). A. baumanii is a hospital acquired pathogen in critically-ill patients. The susceptibility pattern of this study result showed MDR organism. There was a sharp decrease of susceptibility in all antibiotics studied from 2013 to 2014 except amikacin and trimethoprim-sulfamethoxazole.

English

There is mounting evidence that Acinetobacter baumannii has a naturally occurring carbapenemase gene intrinsic in this species. Presence of class 1 integrase gene in Acinetobacter isolates is a useful marker for causing outbreaks in hospitals and for being epidemic strains of A. baumannii. The goal of the present study was to detect the resistance and outbreak marker genes by multiplex polymerase chain reaction (PCR) (blaOXA-51-like gene and class 1 integrase gene). Also to detect the correlation between imipenem susceptibility and detection of blaOXA-51-like gene. For these purposes, 51 consecutive, non-duplicate, A. baumanii strains were isolated from various clinical and environmental specimens from the Intensive Care Units (ICUs) of Assiut University Hospitals, Egypt. All the isolates were identified by conventional standard methods. The antibiotic sensitivity pattern was determined by Kirby Bauer disc diffusion method. For imipenem, the minimum inhibitory concentrations (MICs) were determined using Epsilometer (E test). Multiplex PCR was performed for the detection of the blaOXA-51-like and Class I integrase genes. The blaOXA-51-like gene was detected in (95.8%) and (96.3%) in clinical and environmental isolates, respectively. Class I integrase gene was detected in (75%) and (70.3%) in clinical and environmental isolates, respectively with statistically significant difference (P value of clinical samples = 0.041 and P value of environmental samples =0.011). This means that these strains have metallo-beta-lactamase (MBL) gene (cause outbreak in hospital at any time). Also (67.35%) of A. baumanii isolates are imipenem sensitive and positive for blaOXA-51-like gene and this means that these isolates contain hidden metallo beta lactamase MBL gene. &nbsp; Key words: Acinetobacter baumanii, blaOXA-51-like genes, Class I integrasegene, MBL gene.&nbsp