Assessment of Biofilm Formation and Resistance to Imipenem and Ciprofloxacin among Clinical isolates of Acinetobacter baumannii in Tehran

Abstract

Background:Biofilms are communities of bacteria attached to the surfaces in an extracellular polymeric matrix which are associated with many chronic infections in humans. Acinetobacter spp. are emerging as a major cause of nosocomial infections and Acinetobacter baumannii is the predominant species associated with this kind of infections.Objectives:In the present study, the potential of biofilm formation of clinical isolates, A. baumannii, was assessed by using crystal violet method. Furthermore, susceptibility pattern of these strains to ciprofloxacin and imipenem was determined.Methods and Materials:Biofilm formation by 75 A. baumannii isolates was evaluated by using microtiter plate and tube methods and crystal violet staining. Tube method was carried out under static and shaking conditions. Then, the susceptibility of isolates to ciprofloxacin and imipenem was determined.Results:Results showed that in tube method under shaking, 22% of clinical isolates were strong biofilm producers while 23% of them were not able to form biofilms. In this experiment, 18% and 42% of isolates were considered as moderate and weak biofilm-forming strains, respectively. In microtiter plate tests, 18% of strains were strong-biofilm producers and 25% of them were notable biofilm producers. In this assessment, 10% and 47% were considered as moderate and weak biofilm-forming isolates, respectively. The susceptibility tests, using microdilution method, confirmed that 92% of these isolates were resistant and 6.6% were susceptible to ciprofloxacin, although these results for imipenem were 68% and 24%, respectively.Conclusions:It can be concluded that most of A. baumannii isolates can form biofilm in microtiter plate and tube. The results also verified that most of these isolates were resistant to ciprofloxacin and imipenem.

Biofilm Production by Multi Drug Resistant Bacterial Pathogens Isolated From Patients in Intensive Care Units in Egyptian Hospitals

“…These results was higher than that presented by Abdi-Ali et al in Tehran, which presented that 28% of the isolates were strongly adherent, while 41% were moderately adherent and 25% were non adherent [31]. This difference may come from the genetic diversity of MDR A. baumannii isolates between Egyptian and Iranian hospitals.…”

“…Results of microtiter plate method confirmed by the molecular detection of specific genes responsible for biofilm formation by many MDR bacteria as A. baumannii which might increase the colonization and persistence of bacteria that may lead to higher rates of device related infections [31].…”

“…In this study, no significant disagreement between the tube test results and microtiter-plate was observed. While in the study conducted by Abdi-Ali et al, considerably more strains were classified as weak adherent by the quantitative microtiter-plate method [31]. Factors that may affect the adherence of A. baumannii, P. aeruginosa and S. maltophilia including the hydrophobicity of the test tubes and shaking which raises the chances of bacterial interaction with the glass surface and uniform nutrients dispersion, which may be the main reasons for the difference in results between both studies.…”

The Correlation Between Biofilm Formation and Drug Resistance in Nosocomial Isolates of Acinetobacter baumannii

“…Biofilm-forming A. baumannii have been reported to show high levels of resistance (> 75%) to imipenem, ciprofloxacin, cefotaxime, amikacin and aztreonam in India (15,17). In an Iranian study, 92% and 68% of the isolates from urinary catheter isolates were resistant to ciprofloxacin and imipenem, respectively (18). Our results showed 100% resistance to both imipenem and ciprofloxacin.…”

Evaluation of biofilm formation activity of standard microorganism strains

“…This structure may exhibit different phenotype characteristics by the growth speed and gene transcriptions of the microorganisms [1][2][3].…”