Isolation of Bacteria from Different Surfaces of a Hospital Wards and Clinical Laboratory in Karachi, Pakistan, With Determination of Biofilm Forming Property

Abstract

Purpose of Study: The present research study is based on the isolation and evaluation of the bacteria forming biofilm which is mainly associated with hospital acquired infections and nosocomial infections. Biofilms play important role in bacterial defense and make them more resistant to available antimicrobial drugs which lead to serious health problems. Inhibition of bacterial biofilm formation is very necessary to overcome the nosocomial infections incidences because such bacteria become more pathogenic and virulent.

Methodology: Collection of swab samples was carried out from the different surfaces of Emergency ER, ICU, CCU, Wards and Clinical laboratory at the Memon Medical Institute (MMI) Hospital, Karachi, Pakistan.

A total of 250 samples were collected and cultured at Mueller Hilton Agar (MHA) with the standard growth requirements for bacteria. The bacterial growth positive cultures were isolated and identified through the cultivation on the differential media like Blood agar for gram-positive and MacConkey’s agar for gram-negative bacteria. Biochemical colonial and morphological evaluation of bacteria was done for the identification of bacteria on the specie level. Determination of biofilm forming property of isolated bacteria was done with the Congo Red Agar (CRA) method and confirmative analysis was done with the help of trypticase soya broth (TSB). Out of 250 swab samples 80 samples were observed with bacterial growth and 20 fungal cultures were isolated.

Result and Conclusion: Out of 80 bacterial cultures, 33 were identified as Bacillus subtilis, 11 as Escherichia coli and 29 as Staphylococcus aureus. The number of biofilm forming isolates on CRA is 15 Bacillus subtilis, 4 Escherichia coli and 12 Staphylococcus aureus. Sub culturing of bacterial cultures was done on enriched CRA plates and the raise in biofilm formation was observed as 18 Bacillus subtilis, 5 Escherichia coli and 15 Staphylococcus aureus.