Incidence, root causes, and outcomes of surgical site infections in a tertiary care hospital in Rwanda: a prospective observational cohort study

Surgical Site infections (SSI) are the infection following an invasive surgical procedure and are the most frequently reported hospital acquired infections (HAI) [1, 2]. SSI is a type of hospital-acquired infection (HAI) that arises following surgery and it is related to the surgical site [3]. Currently, SSI is defined as an infection that happens within 30 days of the operation if no implant is left in place or within 1 year of operation if an implant is left in place [4].

SSI may result in increased morbidity and mortality, prolonged hospital stay, increased hospital readmissions even reoperation and healthcare costs [5, 6]. It has been reported by numerous studies that diverse surgical specialties were associated with elevated costs next to the development of an SSI in United Kingdom [7–9]. In the United States, for example, SSI is found to be a serious complication with an incidence of 2 to 5% in patients undergoing surgery complicating approximately 300,000 to 500,000 surgeries per year and costing the health-care system upward of $1.6 billion [10, 11]. SSI is the most common surgical complications in both developed and developing countries [12]. Fan Y.et al., 2014 reported 4.5% to be an average incidence of SSI in mainland China from 2001 to 2012 and abdominal surgery to be the most common surgical procedure.

The global estimated prevalence of HAI, at any given time, approximates to 1.4 million. Incidence varies widely across countries and surgical procedures; however, it is estimated to occur in at least 2% of surgeries [10]. In low- and middle-income countries (LMIC), SSI incidence may be approximately up to 4 times higher than in high-income countries [11]. In sub-Saharan Africa, various study results showed that SSI rate is higher than in developed counties with incidences ranging from 11 to 18% [10, 12].

In Rwanda, findings from retrospective study on HAI conducted at University Teaching Hospital of Kigali indicated that SSI account for 76.8% of all HAIs in surgical department and that 35% of children with SSI experienced complications [13]. However, data are lacking the incidences of SSI until 30 days-post operation including discharged patients before that period making difficult to estimate the really burden of SSI. Moreover, the lack of published reports on SSI risk factors, microbial pathogens and their antibiotic profile has negatively impacted the prevention and management of this infection. Therefore, there is a need to explore the extent to, and for which reasons patients develop infection after surgery and the common pathogens involved in SSI in Rwanda.

The aim of the study was to establish the burden of SSI, its risk factors, the etiological bacterial agents associated with SSI and their antimicrobial susceptibility pattern as well as the outcome in patients after surgery in orthopedic and general surgery at University Teaching Hospital of Kigali known as CHUK.

The mean age of the patients was 40.41 years (standard deviation [SD], 16.7 years), with a range of 18–90 years. Half of the patients (56.5%) were between the ages of 26–44 years and the rest were almost equally distributed in the age below 25 years of age (15.7%) and above 45 years of age (17.3%). The majority 203 (69%) of the patients were Males and 91 (31%) were females. Half of the patients (55.4%) had completed primary school and 24.8% had finished high school while 16% were illiterates and only 3.7% had attained tertiary education. Participants’ mean BMI 23.4 ± 2.5 kg/m², with the majority of patients (71%) having healthy weight, 26.7% being overweight and only 1.6% obese. Alcohol consumption was found in 37.1% of patients whereas only 10 (3.4%) patients were smokers. Majority of the surgeries (73.8%) were made of orthopedics cases and cases for general surgery and urology were represented 22.4 and 3.7%, respectively.

As shown in Table 3, Majority of the surgeries 211 (71.8%) were performed by licensed Surgeons and 83 (28.25) were performed by Residents in training. There were 142 (48.3%) elective operations and 152 (51.7%) emergency operations. Severity of disease, measured using American Society of Anesthesiologists (ASA) score, ranged from healthy (class I) to severe systemic disease, which is a constant threat to life (class IV). High proportions of patients (71.8%) were found in the class I. Majority of operated patients (98.9%) and all patients who developed SSI were discharge from the hospital while 3 patients died.

Bacterial isolates and their antimicrobial susceptibility profiles

swabs from all patients with SSI were cultured and tested for antibiotic susceptibility. A positive culture was obtained from 32 out of 34 swabs. As it is depicted from Fig. 1, among the cultures with positive growth, the most common organism was Klebsiella ssp with an incidence of 55%, followed by Escherichia coli (15%) and Proteus ssp (12%). Other bacteria isolated were Acinectobacter (9%), Staphylococcus aureus (6%) and coagulase-negative staphylococci (3%).

As it is demonstrated in Fig. 2, antibiotic sensitivity profiles were reported for the organisms isolated from surgical incision sited in patients with SSI. The pathogens showed very high resistance toward amoxy-clavilinic acid (98.8%), gentamicin (92.6%), ciprofloxacin (78.1%) and ceftriaxone (53.3%). Amikacin and imipinem were the only two most effective antibiotics with 100% of isolates tested sensitive to both antibiotics.

This study has attempted to estimate the burden of SSI by determining not only its incidence and risk factors, but also the etiological bacterial agents associated with SSI and their antimicrobial susceptibility pattern at a referral and tertiary healthcare institution in Rwanda. To our knowledge, this is the first SSI surveillance study in Rwanda, which describes incidence and associated risk factors of SSI using CDC definitions and 30-day follow-up surveillance.

The finding of this study are based on operated cases, of which, the majority (73.8%) were made of orthopedics cases and cases for general surgery and urology were represented 22.4 and 3.7%, respectively. In this study, the overall incidence of SSI was 10.9%, which is comparable to the average of 11.8% in developing countries [4, 16].

The incidence reported here appears to be also of the same magnitude as that reported in a study in India (11%) [17]. However, the incidence rate was higher than those of several developed countries. For example, incidence rates were 1.9% in the United States, 2.2% in Europe, 1.6% in Germany, 1.4% in England, 1.6% in France, and 2.0% in Portugal [18].

The difference observed in the incidence rate of SSI in developed countries compared to developing countries, including Rwanda, may be due to several reasons. These reasons include poor set-up of hospitals (lack of equipment and materials necessary to maintain strict guidelines for asepsis), poor hygiene of patients increasing colonization of skin by bacterial flora, late presentation of patients to healthcare system leading to contaminated wounds, and overwhelmed emergency services due to population burden.

The present findings seem to be consistent with other research which highlighted some SSI risk factors, which are discussed below, such as age, ASA class, wound classification, skill and experience of the surgeon, duration of surgery, blood transfusion and emergency surgery [4, 17]. SSI incidence rate increased with age, which may be due to a poorer immune response and coexistence of other comorbidities. ASA score of 2 or was significantly associated with higher rate of SSI, which may be due to the severity of systemic illness which hinders immunological response in these patients.

SSI incidence rate was higher in contaminated and dirty wounds, not surprisingly, because numerous bacteria, which are the source of the infection, thrive in contaminated/dirty wounds. Consistent with the finding of this study, the skill and grade of the surgeon has been shown to directly affect the incidence of SSI. The more senior and experienced the surgeons, the less likely it was for the patient to develop an SSI.

Two other major risk factors found to be associated with a high incidence of SSI were duration of surgery, which is due to a prolonged exposure of tissue to the environment, prolonged hypothermia and declining levels of antibiotics; long hospital stay, which can be explained by a prolonged stay providing further opportunity for bacterial colonization. Higher rates of SSI in patients who were transfused during surgery can be explained by a reduced Hemoglobin in these patients which may cause hypoxia and impairment in surgical and traumatic tissue oxygenation and healing to favor wound infection.

Emergency surgeries have also been associated with increase in the incidence rate of SSI due like inadequate preoperative preparation, lack of proper control of other medical comorbidities (such as uncontrolled diabetes). Higher frequency of contaminated or dirty wounds in emergency surgeries could also be a contributing factor. Although there was no significant difference in the incidence of SSI in the relation to other potential factors such as timing of prophylactic antibiotic, smoking, BMI, sex, number of staff during, SSI rates seem to be somehow affected by these factors.

In other study, for example, patient factors (smoking, BMI, life style, nutritional status) are associated with resistance of body to germs after operation; similarly, surgical complexity would influence operation duration and exposure possibility [19, 20].

Finally, the microorganisms causing SSI and their antimicrobial resistance patterns were evaluated. Klebsiella ssp with an incidence of 55%, followed by Escherichia coli (15%) and Proteus ssp (12%) were the predominant isolate which is in contrast with the finding of other studies. In these studies, S. aureus, has been found to be the predominant cause of SSI, which is can be explained by its presence in the skin as normal flora and can thus enter to deep site during surgery. However, the results of this study agree with the findings of other studies, in which, Klebsiella ssp was found to be the predominant bacteria isolated [21, 22].

This difference in the distribution of SSI bacteria may be due to variation in common nosocomial pathogens inhabitant, difference in policy of infection control and prevention between countries and hospitals. Although there are no clear explanations of about high prevalence of Entero-bacterial isolates in the current study, but faecal contamination due to poor personnel hygiene or due to post procedural contamination and outbreaks could be the possible reasons.

High resistance rates to commonly used antibiotic, ranging from 53.3 to 98.8%, were observed in bacterial isolates causing SSI in our study. Not surprising, 53.3% of SSI showed resistance to ceftriaxone, which was prescribed as prophylaxis to all who undergoes surgery. Amikacine and Imipinem were the only effective drugs as 100% of SSI bacterial exhibited very high sensitivity.

The presence of multidrug resistant bacteria isolated in SSI has also been described in other studies in developing countries. This remarkably higher resistance may be due to their easily availability and inappropriate use of the drugs in our hospitals.

SSI incidence rate (10.9%) was revealed to be within acceptable international ranges. However, multi drug resistance was seen in half of the isolates leaving clinicians with few choices of drugs for the treatment of patients with SSI. There was statistically significant association of SSI with wound class, longer surgery and hospital stay, surgeon experience and grade and emergency surgeries. Therefore, periodic surveillance of bacteria and antibiotic susceptibility coupled with the implementation of strict protocol for antibiotic administration and operative room regulations are important to minimize the burden of SSI with resistant bacteria pathogens.