Evaluation of Biofilm Formation Capacity of Acinetobacter baumannii Isolated from Clinical Samples in Baghdad Hospitals using Phenotypic Methods


During the period from November/2016 to March/2017, a total of 475 specimens from various clinical sources (wounds, burns, urine, sputum, blood and throat) were collected from patients suffering different infections from a number of hospitals in Baghadad city (Karkh and Resafa), as follows: (Al-Yarmuk, Al-Karama, Al-Karkh, Al- Kadmia, Martyr Gazi Al-Hariry, the Medical city, Al-Kindi Teaching, Al-Imam Ali, Ibn-Al Balady and Baghdad Teaching Hospitals). Acinetobacter baumannii isolates in selective (CHROMagar) and specific differential medium, microscopic features, biochemical tests and API20 NE and VITEK-2 system at probability 98%. Furthermore the identification of isolates depending of molecular method by using polymerase chain reaction (PCR) technique which is used to amplify specific gene by using special primers, to genus level was confirmed finally by detection of 16SrRNA gene while identification of A.baumannii isolates to species level was done by blaOXA-51-like gene, gaving ratio 100%. The results showed that the 83 A.baumannii isolates were obtained from clinical specimens (17.47%), distiributed according to the sources from highest to lowest percentage as follow in 31(25.20%) wound, 21(19.81%) burn, while 10(12.82%) urin, 8(11.94%) sputum, 7(12.72%) blood and low percentage 6(13.04%) from throat. This study focused on the phenotypic to determine methods the ability of biofilm production using three methods includes: Congo red agar (CRA), Tube method (TM) and microtiter plates (MTP). The results showed a significant differences between all 83 A.baumannii isolates. A seventy four isolates (89.15%) have the ability to adherence and produce slim layer with significant differences in thickness degrees (strong, moderate and weak). While 9 isolates which represented (10.84%) from isolates have no ability to adherence and produce slim layer. When comparing between these methods to detect strong biofilm production isolates, the results showed that MTP assay was excelled on CRA and TM at 58(69.87%), 48(57.83%) and 45(54.21%), respectively measured by optical densities values at 630 nm. Conclusion: The study concludes that there a positive correlation between biofilm formation and multi drug resistance A. baumannii. Each of the three phenotypic methods used for detection of biofilm formation has its advantages and disadvantages. But MTP method is most widely used and was considered as standard test for detection of biofilm formation.