Abstract

Background and Objective: Acinetobacter species are opportunistic important pathogens responsible for many nosocomial infections. The purpose of this study was to determine the drug resistan pattern Acinetobacter baumannii and prevalence of ESBL producing strains in Intensive Care Unit patients in Isfahan city hospitals.

Material and Methods: The study was conducted on 100 Acinetobacter baumannii strains isolated from clinical samples.  The Isolates were identified by standard methods and confirmed by PCR method. Drug resistance pattern of isolates was determined by standard disk diffusion method according to CLSI. To identify ESBL producing strains, a Combined Disk phenotypic method was used.

Results: Hundred percent of Acinetobacter baumannii strains was MDR and the maximum antibiotics resistance was shown to cefepime, co-trimoxazole, ciprofloxacin, meropenem and ceftazidime. According to initial screening, 4.5% of strains were producing Extended Spectrum Beta Lactamase enzyme.

Conclusion: The percent of ESBLs producing strains is low. Thus, Combined Disk for initial screening of ESBLs strains and multiplex PCR for rapid detection of ESBLs strains are recommended.   This issue can be a new step in preventing from the spread of Acinetobacter Baumannii Strains in hospitals particularly in intensive care unit.

Keywords: Beta-Lactamases; Acinetobacter Baumannii; Drug Resistance

Abstract

      Background and Objective: Due to the continuous increase of multidrug-resistant Acinetobacter baumannii strains around the world, decision making for an effective treatment of infections caused by this organism depends on the results of antimicrobial susceptibility tests. In this study, the validity of disk diffusion and E-test methods was assessed by their comparison with the reference method of microbroth dilution for three antibiotics of tetracycline, doxycycline and minocycline.

     Methods: Total of 68 A. baumannii isolates were obtained from patients hospitalized in the burn center of Shahid Motahari Hospital in Tehran, Iran. Susceptibility of the Acinetobacter isolates was evaluated using the disk diffusion, E-test and microbroth dilution methods, according to the guidelines of Clinical and Laboratory Standards Institute.

     Results: Among the isolates, 82.3% were tetracycline-resistant (with minimum inhibitory concentration 50 (MIC₅₀) and MIC₉₀ of 32 and more than 32 µg/ml, respectively and 41.2% were doxycycline-resistant (with MIC₅₀ and MIC₉₀ of 4 and more than 32 µg/ml, respectively). Minocycline, with resistance of up to 13.3% (MIC₅₀ and MIC₉₀ of 1 and 8 µg/ml, respectively) showed the highest antimicrobial activity against the A. baumannii isolates. Antimicrobial susceptibility of bacteria was different depending on the type of methods used. No very major error was observed in any of the methods of susceptibility testing. Overall, the level of major and minor errors in the E-test was lower than the disk diffusion method.

     Conclusion: The results of this study indicate that minocycline has notably high antimicrobial activity against A. baumannii compared to other antibiotics of the tetracycline group.

ABSTRACT
          Background and Objective: Prophage sequences are major contributors to interstrain variations within the same bacterial species. Acinetobacter baumannii is a gram-negative bacterium that causes a wide range of nosocomial infections, especially in intensive care unit inpatients. Prophage sequences constitute a considerable proportion of several sequenced complete genomes of A. baumannii. The aim of this study was to investigate the presence of prophage sequences in A. baumannii strains isolated from burn patients, and compare the results with other studies.
          Methods: Presence of eight prophage sequences was investigated in the genome of ten multi-drug resistant A. baumannii isolates obtained from burn sites of 10 burn patients in a hospital in Isfahan, Iran. PCR and sequencing were performed to detect the prophage sequences. The presence of the eight prophage sequences in the genome of A. baumannii strains from other studies was investigated by BLAST analysis of whole nucleotide sequence of prophage sequences.
          Results: The isolates in the present study had different prophage sequence profiles. Two isolates did not contain any of the sequences, while two isolates contained three and two of the prophage sequences. Other isolates contained only one sequence. The prophage sequence profiles observed in this study were not found in A. baumannii isolates from other studies.
          Conclusion: The results of this study indicate that the prophage sequences profile can be useful for studying the epidemiology of A. baumannii strains.
          Keywords: Acinetobacter baumannii, genome, prophage sequences.

ABSTRACT
         Background and Objectives: Acinetobacter species are responsible for a wide range of clinical complications in hospitalized patients. Antimicrobial treatment of clinical strains of Acinetobacter baumannii may be compromised due to multiple-drug resistance to b-lactams. Aim of this study was to determine antibiotic resistance patterns and frequency of PER and VEB genes in A. baumannii isolates from hospitalized patients.
          Methods: In this cross-sectional study, 100 clinical strains of A. baumannii were isolated from patients hospitalized in Qom (Iran) using specific culture media and biochemical tests. The disk diffusion method was performed to determine resistance to some antibiotics. Minimum inhibitory concentration (MIC) for cefepime and ceftazidime was evaluated. Identification of ESBL-producing strains and presence of the PER and VEB genes were determined by combined disk test and polymerase chain reaction, respectively.
         Results: The isolates were highly resistant against cefixime, ceftriaxone and cefepime. Lowest level of resistance was against polymyxin B. In addition, 70% of the isolates were multi-drug resistant. MIC<128 µg/ml to ceftazidime and cefepime was observed in 84% and 91% of the strains, respectively. Moreover, 21% of the strains were ESBL-positive and frequency of the PER and VEB genes was 47% and 32%, respectively.
        Conclusion: Majority of A. baumannii isolates are highly resistant to the tested antibiotics. Due to presence of the PER and VEB genes in the isolated strains, there is the possibility of resistance spread to other bacteria. Therefore, it is recommended to modify the consumption pattern for antibiotics and pay more attention to standards of nosocomial infection control.
         Keywords: Acinetobacter baumannii, Drug resistance, PER, VEB.

ABSTRACT
          Background and Objectives: Acinetobacter baumannii is an opportunistic pathogen associated with nosocomial infections. Treatment of infections caused by this bacterium has become challenging due to increasing rate of resistance to a wide range of antibiotics such as carbapenems. One of the main mechanisms of resistance to carbapenems is the production of carbapenemase. The objective of this study was to evaluate antibiotic resistance patterns and frequency of carbapenemase-producing A. baumannii strains using the CarbAcineto NP Test.
          Methods: In this descriptive cross-sectional study, 130 A. baumannii isolates were collected from clinical specimens of teaching hospitals in Zahedan in 2016. After determining the antibiotic resistance patterns, all A. baumannii isolates were examined using the phenotypic method of CarbAcineto NP test to evaluate production of carbapenemase enzymes.
          Results: Based on the antibiogram results, more than 90% of the isolates were resistant to the antibiotics tested in this study. However, the lowest rate of resistance was observed against colistin, minocycline, tigecycline and doxycycline, respectively. Based on the results of the CarbAcineto NP test, 96% of carbapenem-resistant strains were positive for the production of carbapenemases.
          Conclusion: Due to the high resistance of A. baumannii to carbapenems, they are not currently suitable for the treatment of infections caused by this bacterium. However, since most carbapenem-resistant strains are susceptible to colistin, minocycline, tigecycline, and doxycycline, these antibiotics or their combination are recommended for the treatment of the infections caused by the resistant strains. Rapid identification of carbapenemase-producing bacteria using efficient methods such as CarbAcineto NP test is essential to prevent their spread, particularly in hospitals.
          KEYWORDS: Acinetobacter baumannii, Carbapenemase, CarbAcinetoNP Test.

ABSTRACT
            Background and Objectives: Acinetobacter baumannii is an opportunistic pathogen that affects different groups of people, especially intensive care unit (ICU) patients. The prevalence of infections caused by this bacterium is very high. Today, prevalence of infections caused by multidrug-resistant (MDR) and extreme-drug resistant (XDR) strains is increasing. This study aimed to determine the antibiotic susceptibility pattern of A. baumannii isolates from ICU patients.
            Methods: This cross-sectional study was conducted from October 2014 to March 2015 on patients admitted to ICU of Imam Khomeini hospital in Tehran, Iran. Clinical samples of various sources were collected from patients. Isolates were detected and identified via microbiological and biochemical tests as well as PCR amplification of the bla_Oxa51 gene. Then, susceptibility testing was performed using the Kirby-Bauer disk diffusion test. Statistical analysis was performed with SPSS (version 22, Chicago, IL, USA) using Chi-square and Fisher’s exact tests.
            Results: Of the total of 62 clinical samples, 24 (39%) were respiratory samples and only three (6%) were cerebrospinal fluid samples. Most MDR and XDR strains were isolated from respiratory samples. The highest resistance rate was against ceftriaxone, ticarcillin and erythromycin (100%), while the lowest resistance rate was against to minocycline (20%).
            Conclusion: Owing to detection of high multi-drug resistance isolates in the present study, and importance of multi-drug resistance in A. baumannii, the identification of multi-drug resistance genes and their reporting to health care/treatment centers is important. Thus, it is recommended to perform susceptibility testing to help determine the most effective antibiotic(s) for the treatment of infections in ICU patients.
            Keywords:  Acinetobacter baumannii, MDR, XDR, ICU.

Background: Acinetobacter baumannii (A. baumannii) has emerged as the predominant etiological agent responsible for bloodstream infections among hospitalized patients. The objective of this study was to evaluate antibiotic resistance in A. baumannii isolates identified from blood cultures.
Methods: A retrospective cohort evaluation was conducted on 117 A. baumannii isolates obtained from blood cultures collected between 2018 and 2019 at the Microbiology Laboratory of Tokat Gaziosmanpaşa University Hospital (Türkiye). The blood culture samples were incubated using the BACT-ALERT 3D system (bioMérieux, Durham, NC, USA). Microorganism identification and antibiotic susceptibility testing were performed using the VITEK 2 (bioMérieux, France) automated system.
Results: Of the 117 samples, 59.8% were obtained from males and 40.2% from females. A total of 90.6% of blood culture samples were collected from the intensive care unit, and 88.9% of isolates were identified as multidrug-resistant (MDR). The highest resistance was observed against meropenem (99.1%), while the lowest resistance was noted for colistin (17.1%) and tigecycline (27.3%). Resistance to amikacin was 74.4%, while resistance levels to gentamicin, tobramycin, cefoxitin, and cefotaxime were within the range of 80–90%. Resistance to imipenem, amoxicillin/clavulanic acid, ampicillin/sulbactam, ceftazidime, cefepime, ciprofloxacin, levofloxacin, meropenem, and ertapenem exceeded 90%.
Conclusion: The increasing number of MDR A. baumannii isolates poses a significant threat to all hospitalized patients. However, colistin and tigecycline remain preferable options for the treatment of MDR A. baumannii infections. Considering the increasing prevalence of MDR A. baumannii isolates, periodic analysis of epidemiological data in healthcare centers is important for managing resistance to colistin and tigecycline.