Isolation of Staphylococcus aureus Isolates from hospital environment and susceptibility to common antibiotics and disinfectants

Abstract

Staphylococcus aureus is a major pathogen associated with serious community and hospital-acquired diseases. Penicillinase producing Staphylococcus aureus was isolated shortly after penicillin G became available. This study aimed to isolate Staphylococcus aureus from the air of operation room, Nursing rooms and natural delivery room of the Military Hospital and to determine the efficiency of commonly used disinfectants and antibiotics against isolated Staphylococcus aureus. Staphylococcus aureus was isolated and identified according to the standard methods based on the morphological, cultural characteristic and biochemical reactions. Kirby -Bauer disc diffusion method was used to assess the susceptibility of the isolated Staphylococcus aureus to antibiotics (Clindamycin (2µg), (Trimethoprim (1.25 µg) + sulfomethazole (23.75 µg)), Azithromycin (15 µg), Methicillin(5 µg), Gentamycin(10 µg), Vancomycin (30 µg)) and towards some commonly used disinfectants ( Chloroxylenol (Dettol) , Harbic Power plus Disinfectant (Harbic) and Sodium hypochlorite (Chlore )) each disinfectant was used at different concentration of 100% , 20% , 15% , 10% , 5% ). Staphylococcus aureus was isolated from 76.9% of the collected air samples, from these the natural delivery room showed the highest percentage of isolation of Staphylococcus aureus, 94.4% of the collected samples reveled positive growth while only 5.6% showed negative growth of Staphylococcus aureus, Staphylococcus aureus was isolated from aseptic nursing room as 73.3% of a collected samples, while septic nursing and operation room showed percentage of isolation of 68.8% from both of them. From the isolated Staphylococcus aureus 54% of them were isolated as mixed with one organism while 46% of them were mixed with more than one bacteria . The largest inhibition zone was shown with chlorxylenol (Dettol) as 48 mm at concentration of 100% followed by 47.9 mm with Harbic power plus 100%. Dettol disinfectant showed decrease in the size of the inhibition zones gradually with the decrease of the concentration of the Dettol. On the other hand Harbic inhibited the growth of Staphylococcus aureus, at concentration of 100%, 20% and 15% gave inhibition zones of 47.9 mm,25 mm and 17 mm respectively ,At concentration of 10% and 5% Harbic had no antimicrobial activity against Staphylococcus aureus . Sodium hypochlorite (Chlore) gave the lowest activity against Staphylococcus aureus it gave inhibition zone of 34 mm at concentration 100% only while 20%, 15%, 10% and 5% showed no activity against Staphylococcus aureus. The isolated Staphylococcus aureus showed high sensitivity toward Vancomycin (30µg) 72%of other Isolates were sensitive to vancomycin (30µg), 12% showed intermediate sensitivity while 16 % of other Isolates were resistant to vancomycin (30µg). The isolated Staphylococcus aureus showed sensitivity towards Clindamycin (2µg) and (Trimethoprim (1.25µg) + sulfomethazole (23.75µg))as 48% and 42% respectively .The highest sensitivity was observed with gentamycin (10 µg) as 90%. On the other hand 90% of the isolates were resistant to methicillin (5 µg), 46% resistant to Trimethoprim (1.25µg) sulfomethazole (23.75µg), 68% resistant to Azithromycin (15 µg) and 34% were resistant to Clindamycin (2 µg). The study concluded that the hospital environment harbor pathogenic Staphylococcus aureus and the isolation of the methicillin resistant Staphylococcus aureus (MRSA) is of highly health concern.