MICROBACTERIAL PROFILE OF SURGICAL SITE INFECTION AND THEIR PATTERN OF SENSITIVITY IN TERTIARY HOSPITAL IN NORTH CENTRAL HOSPITAL, NIGERIA

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A.A. Abiodun¹, A.O. Adekanye¹, C.N.D. Nwachukwu², T.S. Ayanbeku³, J.A. Abiodun⁴

1. Department of Surgery, Federal Medical Centre, Bida.
2. Department of Obstretrics and Gyneacology, Federal Medical Centre, Bida.
3. Department of Microbiology, Federal Medical Centre, Bida.
4. Department of Community Health, Federal Medical Centre, Bida.

Abstract

Background: Surgical site infections (SSI) remain a problem in surgical practice despite the improvement in advanced technology and the use of antibiotics. Also, there is also a growing menace of antibiotic resistance which poses a great challenge in treating SSI. The study aimed to find out the most common bacterial pathogens responsible for surgical site infection and their antibiotic sensitivity profile.

Material and Methods: It was a descriptive study carried out in Federal Medical Centre, Bida. 500 surgical procedures were carried out and samples were obtained from 73 patients that showed clinical evidence of SSI for culture and susceptibility test. Samples were collected from each patient using a swab stick. Bacteriological culture examination and identification were done following standard microbiological techniques. Susceptibility testing was performed by Kirby-Bauer technique according to Clinical and Laboratory Standards institute 26th edition. Data were analysed using SPSS 26.

Results: Out of the 73 samples taken, 83 isolates were obtained while five samples yielded no growth. Gram-negative bacteria (GNB) were predominant in 73(88.1%) with the dominant being E. Coli species (38.6%). From the strains that were isolated, there were 9(10.8%) Staph aureus was the only Gram-positive organism. Concerning antibiotic susceptibility, the results demonstrated remarkably high multidrug resistance. However, the meropenems and amikacin demonstrated good activities against all gram-negative isolates. The resistance pattern of enterobacteriaceae to tested antibiotics were to ciprofloxacin (90.2%) levofloxacin (82.2%) augmentin (88.5%) ceftriaxone (85.2%) ceftazidime (80.3%), gentamicin (80.3%) meropenems (14.8%) amikacin (16.4%.).

Conclusions: The study demonstrated a high alarming rate of multidrug resistance following SSI and this should call for concerns and surveillance among surgeons.

Keywords: Antibiotics, Antibiotic resistance, Bacteria

Introduction

The Centers for Disease Control and Prevention defines Surgical site infections as those infections which are confined to the incisions and involving structures adjacent to the wounds that were exposed during operation within one month after a surgical operation or one year after implant surgery.¹ According to WHO, surgical site infection (SSI) is the most common healthcare-associated infection in low and middleincome countries and can affect up to one-third of surgical patients.² The overall incidence of SSI is 14.8% in sub-Saharan Africa.³ From a meta-analysis the cumulative incidence of SSI in Nigeria was 14.5%.⁴ In a single centre study from a tertiary hospital in Nigeria, health care associated infection was 2.7% and SSI accounted for 30.4% of it.⁵ Once a surgical wound is infected, it is usually associated with prolonged postoperative hospital stays, additional surgical interventions, and higher mortality.⁶ The most common organism commonly isolated from SSI are S. aureus, Klebsiella species, E. coli, Proteus species, Streptococcus species, Enterobacter species, and Pseudomonas species.⁷ Antimicrobial resistance (AMR) is now considered a major threat to global health.⁸ Antibiotic resistance can occur naturally but there are many reasons behind the emergence and acceleration process of AMR which may be due to misuse (underdosing and overuse) and over-prescription of antimicrobials.⁹ Resistance to antibiotics has made infections difficult to treat and may impinge on the quality of care given to a surgical patient through its associated morbidity, mortality, and significant economic consequences.¹⁰

This study was aimed to determine the spectrum of bacterial pathogens isolated from infected surgical sites and their antimicrobial susceptibility profile in the Federal Medical Centre, Bida, with the view of providing guidelines to the surgeons for making rational decisions over the choice of antibiotics in the management of SSIs.

SUBJECTS AND METHODS
This was a prospective study conducted at Federal Medical Centre (FMC), Bida for 6 months from 1st May 2019 to 30th November 2019. FMC, Bida is a tertiary hospital in Niger State, North-Central Nigeria with a bed capacity of 200. All patients one month above who had undergone surgical procedures and developed SSI as diagnosed clinically by physicians within 30 days were recruited after surgery. A patient was considered to have surgical site infection, if there was pus or seropurulent discharge from the surgical wound with signs of sepsis. Patients who developed an infection from episiotomy and circumcision were excluded. A pre-tested proforma was used to obtain patients’ demographics, clinical diagnosis, date of admission, personal history, and date of surgical procedure and prophylactic antibiotics.

All samples were collected from infected surgical site early in the morning before dressing the wounds using sterile cotton swabs. The swab was firmly applied, and slowly rotated thoroughly covering the surface of the wound. The swab specimens were transported to the microbiology laboratory of the hospital within one hour of collection. The samples were processed by the standard laboratory procedure. These included direct gram stain, culture, identification of organism and antibiotic susceptibility testing on the organism. Culture of specimen: The swabs were inoculated on blood agar and MacConkey agar for culturing and isolation of organisms. The culture plates were incubated at 35°C – 37°C aerobically for 18-24 hours. The culture positive isolates were identified by their colony morphology, gram stain reaction, and also motility testing according to standard methods. Pure colonies were characterized biochemically for species identification. Antibiotic susceptibility testing was performed by Kirby-Bauer technique according to the Clinical and Laboratory Standards Institute 26th edition by disc diffusion method.¹¹ From a pure culture, 3-5 pure colonies of bacteria were taken and transferred into a tube containing 5 ml sterile nutrient broth (Oxoid) and mixed gently until the turbidity of the suspension become adjusted to a McFarland 0.5 standard. Using a sterile cotton swab, the bacteria were seeded evenly over the entire surface of Mueller-Hinton agar (pH 7.2-7.4) (Oxoid). The plates were left at roomtemperature to dry for 3-5 minutes and a set of antibiotic discs (Oxoid) with the recommended concentrations was placed on the surface of the inoculated Muller-Hinton plate. Finally, the plates were incubated at 35ºC-37ºC for 18-24 hours. Diameters of growth inhibition around the discs were measured and interpreted as sensitive, intermediate, or resistantas stated by CLSI 26th edition.¹¹