One year study of aerobic bacterial profile and antimicrobial susceptibility pattern of pus samples

Introduction: Pyogenic wound infection is one of the major cause of morbidity. The pace at which the bacterial isolates develop drug resistance is far exceeding the rate of discovery of newer drugs and thus highlights the need for conducting periodic studies to determine their antimicrobial susceptibility patterns. Materials and Methods: This study was conducted from June 2015 to May 2016, in Santhiram medical college and general hospital. Pus samples submitted to Microbiology department were processed and identified using standard protocols. Antimicrobial testing of all isolates was performed by KirbyBauer’s disc diffusion method as per CLSI guidelines. Results: In our study a total of 490 pus samples were received, of which 279 (56.9%) were culture positive. Gram negative bacilli (78%) outnumbered Gram positive cocci (22%). Majority of samples were from Surgical departments (94.6%). E.coli (29%) was the commonest organism isolated followed by klebsiella spp. (19.7%), Staphylococcus aureus (15.4%). All Staphycoccal isolates were susceptible to Linezolid, Teicoplanin, Vancomycin where as Gram negative bacilli were susceptible to Imipenem (96.7%), Piperacillin-tazobactum (84.7%), Gentamicin (62.2%), Cefeperazone sulbactum (57.6%). Among Pseudomonas isolates, Imepenem (97.2%), Piperacillintazobactum (94.3%), were effective drugs. Conclusion: Microbiological analysis and antibiogram of pus isolates can serve as a useful tool for appropriate and judicial use of antibiotics and thus minimizing the evolution of drug resistance strains in future. © 2020 Published by Innovative Publication. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by/4.0/)


Introduction
Pyogenic infections are associated with local and systemic inflammation characterised with pus formation. 1 The cause of these infections may be either exogenous or endogenous. As the bacteria make their entry into the body, the immune cells accumulate at the site of entry to fight against the bacteria and eventually lead to formation of pus. 2 Several studies have been conducted from time to time to access the bacterial profile and the antibiotic sensitivity pattern in pus samples, which will help the treating physician to start empirical treatment in patients until the lab culture reports are available. 3 Though various studies show similarity in bacterial profile of pus samples, there is much variation in the susceptibility pattern of antibiotics which highlights the emergence of resistant bacteria and also a need for continuous surveillance of such changing trends. The present study was designed to evaluate the profile of aerobic pyogenic bacteria along with their susceptibility pattern to various antimicrobial agents.

Results
A total of 490 samples were received for aerobic culture and sensitivity testing in microbiology lab. 279 (56.9%) isolates were culture positive and 211 (43.06%) were negative. Among culture positives 209 (74.9%) were from male patients and 70(25%) were from females ( Figure 1). Male: female ratio is 2.99. With regard to age distribution among culture positive samples patients between 51-60 yrs contributed 29.3% (Table 1).  followed by orthopaedics (5.73%)and obstetrics and gynaecology

Discussion
In our study, we found the predominance of Gram negative bacteria as the causative agents of pyogenic lesions which is supported by Zubair et al 5 and Ghosh et al. 6 we found that E.coli was the most common organism isolated which differs from the studies of Swati et al 7 and Birader et al 8 where they got Pseudomonas spps and staphylococcus aureus respectively. The above variation can be attributed to much bigger sample size in our study when compared to the mentioned studies.        9 Among Gpc's Staphylococcus aureus is the most common isolate in our study which also corelates with the studies of Tivari et al 10 and LeeCY et al, 11 but the prevelance of Methicillin resistant Staphylococcus aureus (MRSA) was low in our study 4 (9.3%) when compared to the studies Swati et al (35.9%). The reason can be because of the variation in the location of the hospitals where the studies were done. As our study was done in a hospital located in a rural area where the usage of higher class antibiotics was much lower when compared to above mentioned studies which were done in hospitals located in urban areas. All isolates of Staphylococcus aureus are 100% sensitive to vancomycin, which correlates with studies of Samra et al 12 15 As surgical departments contributed to more numb er of culture positive isolates, it highlights the need for proper antibiotic coverage among the patients. In our study all the isolates of E.coli were sensitive to imipenem but in studies of Birader et al and Rhaghav et al 20% of isolates were resistant to imipenem.

Limitations of Our Study
1. Anerobic cultures were not done. 2. Lack of adequate history on prior antibiotic usage before sample was sent to the lab.

Conclusion
Pyogenic infections are a major concern in health care settings as they are the major cause of morbidity in many occasions. The situation has been more worsened now a days with the emergence of multidrug resistant strains. Inspite of some limitations, the present study can serve as an useful tool for clinicians for appropriate and judicial use of antibiotics which not only contribute to the better treatment but also aids in prevention of emergence of drug resistant strains in future.

Source of funding
None.

Conflict of interest
None.