Correlation of biofilm formation and antibiotic resistance among clinical and soil isolates of Acinetobacter baumannii in Iraq

Abstract

Acinetobacter baumannii is an opportunistic pathogen that is reported as a major cause of nosocomial infections. The aim of this study was to investigate the biofilm formation by A. baumannii clinical and soil isolates, to display their susceptibility to 11 antibiotics and to study a possible relationship between formation of biofilm and multidrug resistance. During 8 months period, from June 2016 to January 2017, a total of 52 clinical and 22 soil isolates of A. baumannii were collected and identified through conventional phenotypic, chromo agar, biochemical tests, API 20E system, and confirmed genotypically by PCR for blaOXA-51-like gene. Antibiotic susceptibility of isolates was determined by standard disk diffusion method according to Clinical and Laboratory Standard Institute. The biofilm formation was studied using Congo red agar, test tube, and microtiter plate methods. The clinical isolates were 100% resistance to ciprofloxacin, ceftazidime, piperacillin, 96.15% to gentamicin, 96.15% to imipenem, 92.31% to meropenem, and 78.85% to amikacin. The soil A. baumannii isolates were 100% sensitive to imipenem, meropenem, and gentamicin, and 90.1% to ciprofloxacin. All A. baumannii isolates (clinical and soil) were susceptible to polymyxin B. The percentage of biofilm formation in Congo red agar, test tube, and microtiter plate assays was 10.81%, 63.51%, and 86.48%, respectively. More robust biofilm former population was mainly among non-MDR isolates. Isolates with a higher level of resistance tended to form weaker biofilms. The soil isolates exhibited less resistance to antibiotics than clinical isolates. However, the soil isolates produce stronger biofilms than clinical isolates.

Correlation between antimicrobial resistance and biofilm formation capability among Klebsiella pneumoniae strains isolated from hospitalized patients in Iran

“…They stated drug resistance was greater in K. pneumoniae which is biofilm producer than non-biofilm producer. However, in contrast to our results, Hassan et al concluded that the susceptible isolates to antibiotics tend to form stronger biofilms compared with the resistant strains [31]. This discrepancy suggests that the tend to form biofilm may be an important factor in the survival of non-resistant strains.…”

Molecular typing of multi-drug resistant Acinetobacter baumannii isolates from clinical and environmental specimens in three Iranian hospitals by pulsed field gel electrophoresis

“…Of the 8 antimicrobials tested, the most potent ones were colistin and tigecycline (100%) for all clinical and environmental isolates. In agreement with previously research who requested, the most effective drug in controlling A. baumannii is polymyxin B [18].…”

Correlation Between Antimicrobial Resistance and Biofilm Formation Capability Among Klebsiella Pneumoniae Strains Isolated From Hospitalized Patients in Iran

“…Using a rat model of middle ear challenge, Yadav et al (2018) demonstrated that the functional defect in LuxS, leading to the reduced colonization capability of pneumococci in vivo [29]. However, in contrast to our results, Pakhshan et al [30] concluded that the susceptible isolates to antibiotics tend to form stronger bio lms compared with the resistant strains.…”