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Pattern and etiological factors of surgical site infection among patients undergone surgery at Sir Salimullah Medical College and Mitford Hospital, Dhaka, Bangladesh

Surgical site infection (SSI), previously called postoperative wound infections, may be defined as an infection that occurs at or near the surgical incision within 30 post-operative days of the surgical procedure, or within 1 year if an implant is left in place (eg, mesh, heart valve). SSI is further classified as(a) superficial incisional; (b) deep incisional; and (c) organ/space SSI. Factors for acquiring infection are host factors, surgical factors, environmental factors, and the nature of microbes. Host factors contributing to increased risk of infection are age, length of hospital stay, and concurrent infection at the other side of the body. Among surgical factors the nature and extensibility of operation, site, and depth of the wound, logistics used and continued during and after an operation, and surgeons’ technical skills are remarkable. ABSTRACT

Among microbial factors virulence and numbers of bacteria are important. Local tissue defense can combat minute inoculums of virulent bacteria. But if host damage is extensive and co-morbidity in the form of diabetes or other immunosuppressive states remains, small inoculums of virulent bacteria can ensure an overwhelming infection occurs. On the other hand, virulent bacteria of drugresistant nature may be the single factor of overt and fulminant infection. [5][6][7] Environment of operation theatre (OT) and surgery ward is a crucial factor for infection.
Excess visitors in general access zone and wards, sneeze, cough, personnel carrying intranasal and facial pathogens results in spreading by droplet due to talk. On settling OT table, trolley, linens, bed etc. transmitted to the operated patients. 8 Surgery team, in the same way, transmits microbial agents to the operation wound. Unclear logistics-all as well as the dirty floor of the ward are risk factors for surgical site infection. 9 Primarily depending on the type of surgical procedure, the pathogens isolated from infections differ. In the clean surgical procedures, in which gastrointestinal, gynecologic, and respiratory tracts have not been entered, Staphylococcus aureus from the exogenous environment or the patient's skin flora is the usual cause of infection. The polymicrobial aerobic and anaerobic flora closely resembling the normal endogenous microflora of surgically resected organs are the most frequently isolated pathogens in other categories of surgical procedures including clean-contaminated and dirty. 10 The single most disadvantage with those microbes stood as their multi-drug resistance property. Newer cephalosporins and quinolones antibiotics are randomly used for prophylactic and therapeutic purposes to overcome this problem, but it is not cost-effective in developing countries.
Many times patients cannot afford those antibiotics due to poverty. So, leading to a chance of emerging resistance to that particular drug by those particular bacteria, the treatment course remains incomplete or improper. This is rather a chronic situation. Hence the high magnitude of antibiotic resistance would rightly be expected and the number of variables that can influence SSI rates is large. In the prevention of SSI, preoperative planning and intraoperative technique for both emergency and elective surgery have become important. Organism in the wound can be reduced via skilled surgical technique, judicious use of electro-cautery can reduce the risk of hematoma, adherence to the principles of prophylactic antibiotic therapy, sound infection-control practice, and better preoperative preparation of the surgical site while performing operations.
Further reducing the rate of SSI, enhancement of host defenses by increasing oxygen delivery, better core body temperature control during the perioperative period, and rigorous blood glucose control in surgical patients are new areas that have the potential to even. Consistent application of proven methods of prevention, continued progress in the biology of infection at the site will allow us to further reduce the frequency, cost, and morbidity associated with SSI. 11

General objective
The objective of this study was to assess the pattern and etiological factors of surgical site infection among patients undergone surgery at Sir Salimullah Medical College and Mitford Hospital, Dhaka, Bangladesh.

Specific objectives
The objectives of this study were (a) to find out the frequency of SSI among patients undergone surgery at SSMC and MH, Dhaka, Bangladesh; (b) to identify the factors responsible for surgical site infection following surgery; and (c) to identify the causative organism for SSI.

METHODS
This cross-sectional study was conducted in the department of surgery, SSMC and MH, Dhaka, Bangladesh during the period from August 2017 to July 2018. Through purposive sampling technic, in total 160 admitted patients who had undergone surgical procedures at the mentioned hospital were enrolled as the study population. According to the exclusion criteria of this study patients presented with infected wounds, needed drainage of abscess, patients of road traffic accident, patients below 12 years of age, and patients having prosthetic surgery were excluded. The study protocol was accepted by the ethical review committee of SSMC before commencing. The patients who were admitted into the department of surgery for undergoing elective surgery were approached for inclusion criteria.
All patients were screened according to inclusion and exclusion criteria prior to final selection. Formal permission was taken from each subject. All patients were interviewed by the researcher for baseline data like age, sex, socioeconomic status, BMI, and co-morbid disease after inclusion and assessment. Moreover, they were investigated for anesthetic fitness as well as to identify comorbidities. All patients were followed up for 30 days following the operation. As mentioned in the operational definition, wound infection or surgical site infection were defined by standard criteria. These infections were managed by both use of proper antibiotics and regular surgical dressing. Before that swabs and blood culture were sent for confirmation of infection and culture sensitivity. Antibiotics were chosen according to the sensitivity report after collection of the culture sensitivity report. Data analysis was done by SPSS 22.0.

DISCUSSION
In this study, all of the patients had undergone elective surgery. The most common surgical procedure performed was cholecystectomy (31.9%), most of them being laparoscopic cholecystectomy. This was followed in the second and third by mastectomy and gastrectomy. Sickder et al found hernioplasty to be the most common elective operation done in their study. 6  Anemia was examined and found to be a risk factor for SSI by Lubega et al who reported that the chance of SSI increased with the degree of anemia. 11 In the study by Mawalla et al, smoking was significantly associated with SSI. By Laloto et al obesities were found to be associated with an increased chance of SSI. 7 To the length of operative procedures, the risk of wound infection had repeatedly been shown to be proportional. When the duration of operation was more than 60 and 150 minutes, a higher incidence of post-operative wound infection was observed

SSIs Site Among The Patients
Superfacial Deep Nur-E-Elahi et al. 8 An increase in wound infections with longer procedures, roughly doubling with every hour of the procedure found by Cruse et al. 12 This may be due to several factors like doses of bacterial contamination increases with time and longer procedures are more liable to be associated with blood loss and shock, thereby reducing the general resistance of the patients. The increased amount of suture and electro-coagulation may also reduce the local resistance of the wounds. The most common organisms isolated through the culture test were S. aureus, Enterococcus spp, Klebsiella spp.; and P. aerginosa. 13 The etiology of SSI may be normal patient flora contaminated either through the surgical equipment or through the environment of entry. Gram-positive pathogens such as Staphylococcus aureus and Enterococcus spp. colonize the skin above the waist. On the other hand, both gram-positive pathogens and gramnegative pathogens normally colonize the skin below the waist. The microbiology of SSI may vary with the particular entry route. 14 Drug sensitivity patterns varied depending on the organism isolated. E. coli showed resistance mostly to cloxacillin, cefixime, ciprofloxacin was sensitive to ceftriaxone, nitrofurantoin, and gentamicin. S. aureas showed high sensitivity to ceftriaxone and meropenem. P. aeruginosa showed high sensitivity to gentamicin and meropenem and complete resistance to amoxycilin, cefixime, ciprofloxacine. In 2011 the study by Nur-E-Elahi et al found that Escherichia coli was found resistant to amoxycillin in 93.02% cases followed by gentamicin in 37.21%, ciprofloxacin in 32.56%, nitrofurantoin in 25.58% and least being ceftriaxone in 11.63%, and in the case of S. aureus. 8 Amoxycillin was (87.88%) followed by cloxacillin (63.64%), gentamicin (48.48%), ciprofloxacin (36.36%), and ceftriaxone (12.12%). P. aeruginosa remained resistant to amoxycillin in all (100%) cases also found in their study. This shows that the resistance of E. coli to ciprofloxacin has increased over time.
But the sensitivity of gentamicin was higher than in their study. Also, for S. aureas sensitivity to amoxicillin and cloxacillin remained constant over time. This was also notable that till now ceftriaxone has remained sensitive to many cases. Without appropriate use of the drug which may decrease. In this study, fortunately, meropenem was found to be 100% sensitive for all bacteria isolated.
As a special technique may not equally convenient for every operating surgeon. Sample size was small to generate representative findings. Patient outcome report could have been subjected to inter and intra observer variations.

CONCLUSION
SSI are serious postoperative complications with a significant impact on morbidity and mortality. In this study, the incidence of SSI among elective postoperative patients at SSMC and MH is high compared to that in the developing world and slightly less than developed countries. Staphylococcus aureus causes the majority of superficial SSIs, whereas E. coli is the most frequent organism isolated from deep SSIs. The development of SSI was associated with hypertension, anemia, DM, increasing age, and malnutrition. Sensitivity screening showed meropenam and gentamycin were the two most potent antibiotics against organisms that cause SSI among the patients. However, the findings provide an idea about the most recent pattern of SSI and its aetiology and further nationwide studies are recommended.