Isolation, Characterization and Antibiotic Sensitivity Pattern of Different Bacteria in Pus Sample

This study was undertaken to determine the frequently isolated organism from pus culture and to determine the antibiotic sensitivity patterns so that it helps to manage the drug resistant organism well in time which poses challenge to clinician to treat the patients. Total 2050 samples were collected from April 2016 to March 2017 to study antibiograms of various organisms. Organisms were identified as per standerd operative procedure and drug sensitivity was done as per CLSI guidelines. Most commonly encountered organism was Staph. aureus followed by Klebsiella, Pseudomonas, Proteus, Citrobacter, E.coli and Acinetobacter. Staph.aureus was showing sensitivity towards Vancomycin, whereas gram negative organisms were showing sensitivity towards Imipenem, Gentamycin, Ciprofloxacin and Ceftriaxone. Antimicrobial resistence is a predictable outcome of antimicrobial use. Lengthy or inappropriate antimicrobial therapy allow microbes to mutate into new forms that help them to survive antibiotic treatment and quickly become resistance strain. Knowledge of local common pathogens and their resistance status can guide clinician to choose appropriate antibiotic for empirical treatment of patients.

Pyogenic infection are characterized by local and systemic inflammation with pus formation . Infection of soft tissue are generally associated with the production of pus and bacteria involved are said to be pyogenic (pus producing). Wide variety of aerobic and anaerobic species of bacteria may be present either singly or in combination in infection of wounds and soft tissue. Some infection resolve without specific therapy but some infection especially mixed infection can cause severe synergic therapy 1 . Antimicrobial resistence is a predictable outcome of antimicrobial use. Lengthy or inappropriate antimicrobial therapy allow microbes to mutate into new forms that help them to survive antibiotic treatment and quickly become resistance strain. Knowledge of local common pathogens and their resistance status can guide clinician to choose appropriate antibiotic for empirical treatment of patients 2. Various studies across the world have shown periodic monitoring of the bacterial profile in the pyogenic wound infection, which is helpful for the empirical treatment of the patient. Keeping this in mind this study has been undertaken to know the common organism involved and their antibiogram in our set up.

MATERIALS AND METHODS
This is a Retrospective study conducted in department of Microbiology, Silchar Medical College, Silchar. In the present study the data was collected from the period April 2016 to March2017. The total number of 2050 pus sample were collected from cases of pyogenic infection attending both OPD and indoor in the department of Surgery, O&G, Orthopaedics and ENT. Under strict aseptic condition sample were collected and transported to the Department of Microbiology for processing. The media and reagents are purchased from HIMEDIA laboratories. Mumbai, India. First , samples were inoculated in 5% sheep Blood agar and MacConkey agar culture media, then it was subjected to Gram staining of direct smear and Gram stain was examined for the presence of pus cells and any bacteria. The inoculated media were incubated aerobically at 37® C for 24 hours. If there was no growth, incubation time is extended up to 48 hours to be considered sterile. All the bacteria growing on blood agar and MacConkey agar were examined to look for the colony character, Gram staining and motility.  (4) .For antimicrobial sensitivity testing Muller Hinton agar was used. The antimicrobial disc used were purchased from HiMedia laboratory Ltd. Inhibition zones were measured and reported as sensitive or resistant according to manufacturer, s guidelines. Escherichia coli ATCC 25922,Pseudomonas    7%). The antibiogram of gram positive cocci showed 100% sensitivity to vancomycin and Linezolid followed by high sensitivity to Azithromycin, Cefuroxime while moderate sensitivity was observed to Cefoxitin, Levofloxacin Ampicillin and Amoxycillin/ clavulanic acid.Gram positive cocci showed high resistence to Ciprofloxacin, Ceftriaxone and Amikacin. MRSA noted was 75.68%. The antibiogram of enterobacteriaceae (Klebsiella and Proteus ) showed high susceptibility to Imipenem. E. coli showed highest susceptibility to Amikacin and Levofloxacin.Citrobacter showed highest susceptibility to Levofloxacin.High resistence is observed towards Ceftazidime (Klebsiella), Aztreonam (E.coli), Cefuroxime (Proteus) and Citrobacter (Ceftriaxone) respectively. Pseudomonas and Acinetobacter showed maximam susceptibility to Piperacillin/tazobactam .

DISCUSSION
The prevalence of culture positive pus samples in our study is 50.73% . The observation of this study very well coincide with the works reported by various authors across the country .S.aureus was found to be the most commonly occurring pathogen in study group done by Tiwari et al 5

CONCLUSION
The result of the above study exemplify there is an increasing need for gaining knowledge about the pattern of microbes and their antibiotic sensitivity and resistance, which varies in a geographical manner.The isolates from this study showed that Staphylococcus aureus was the most isolated organisms from the pus culture report followed by Klebsiella,Pseudomonas, Proteus, Citrobacter, E.coli and Acinetobacter.
In Staphylococcus aureus Vancomycin showed highest sensitivity followed by Enterobacterecia showed highest sensitivity to Imepenem , Levofloxacin. Nonfermenter like Pseudomonas and Acinetobacter also showed highest sensitivity to Piperacillin/Tazobactam. Knowledge of causative agents of pyogenic infection and their antibiotic sensitivity pattern is very essential for the judicial administration of empirical therapy before culture result are available. Antibiotic sensitivity of microorganism varies from place to place and time to time, hence regular monitoring of bacterial sensitivity to antibiotics is essential. However there is a scope for further study of microorganism in other clinical specimen also to know their antibiotic sensitivity will invariably add to the knowledge of our microbiologist and clinician.