• Prevalence of Extended Spectrum β-Lactamase Escherichia coli, Klebsiella spp. and Proteus spp in bronchoalveolar lavage samples by disk diffusion and molecular methods in Tabriz, Iran
  • Farzin Samadi,1,* Sara Didar,2 Toran Ebrahimi,3 Arian Beigy,4 Yasaman Asadpour,5 Amin Saadat Asqarkhani,6
    1. Department of Microbiology and Parasitology, Kia Tashkhis Ayaz laboratory, Urmia, Iran
    2. Department of Microbiology and Parasitology, Kia Tashkhis Ayaz laboratory, Urmia, Iran
    3. Department of Microbiology and Parasitology, Kia Tashkhis Ayaz laboratory, Urmia, Iran
    4. Department of Microbiology and Parasitology, Kia Tashkhis Ayaz laboratory, Urmia, Iran
    5. Department of Microbiology and Parasitology, Kia Tashkhis Ayaz laboratory, Urmia, Iran
    6. Department of Microbiology and Parasitology, Kia Tashkhis Ayaz laboratory, Urmia, Iran


  • Introduction: Resistance to a wide range of common antimicrobials has made the proliferation of extended-spectrum beta-lactamase (ESBL)--producing strains a serious global health concern, complicating therapeutic strategies. The high proportion of ESBL producers among Enterobacteriaceae and the complex molecular epidemiology with different types of ESBL genes are of concern. ESBLs are plasmid-mediated groups of enzymes that hydrolyze penicillins, extended-spectrum cephalosporins, and aztreonam. This study was conducted to identify ESBL production in different Gram-negative bacilli isolated and further identify ESBL producers among Escherichia coli and Klebsiella bacteria by PCR method in Tabriz city.
  • Methods: A total of 2000 isolates of gram-negative bacilli were isolated by examining more than 5000 Bal culture samples. Then, all the isolated bacteria were identified by microbiology diagnostic methods such as differential media and diagnostic discs. The presence of ESBL positivity was detected using a double disc synergy test (DDST). The discs used in this experiment were ceftazidime and ceftazidime clavulanate. After antibiogram analysis, PCR for beta-lactamase (bla) genes of SHV, TEM and CTX-M family was also performed using primers designed in 25 ESBL isolates of each Escherichia coli, Klebsiella and Proteus species.
  • Results: Among 2000 Gram-negative bacilli isolated, 820 (45.69%) were ESBL producers. The main source of ESBL production was bronchoalveolar lavage samples, with the highest ESBL production in Klebsiella sp. (65.12 %). Resistance to multiple classes of antibiotics was observed among ESBL producers. Among the bacteria that can have EBLS resistance, Proteus was the least of all. Among ESBL-producing genes, the prevalence of bla-CTX-M (70.3%) was the highest, followed by bla-TEM (48.2%) and bla-SHV (56.3%) in the present study. The frequency of ESBL-producing strains among clinical isolates is steadily increasing. Monitoring advanced drug resistance and molecular characteristics of ESBL isolates is essential to guide the appropriate and judicious use of antibiotics.
  • Conclusion: Gram-negative bacilli that are multidrug-resistant have been increasingly responsible for life-threatening illnesses all over the world. Multiple risk factors were associated with ESBL infections both in the community and hospital setting It must be given importance. Prediction tools are needed to improve the protocol of appropriate empiric antibiotic selection while preserving antimicrobial stewardship recommendations.
  • Keywords: Extended-spectrum β-lactamase (ESBL), bronchoalveolar lavage, Double Disk Synergy Test (DDST), Antib