INTRODUCTION

Surgical site infection (SSI) is one of the most common and serious hospital-acquired infections all over the world [1-3]. According to the Centre for Disease Control and Prevention (CDC), surgical site infection is defined as "post-operative infections that develop in 30 days after any surgical procedure or within one year of any implants [4]. All over the world, around 300 million surgeries are performed every year. This increasing number of surgeries leads to an increase in the incidence of postoperative wound infections on surgical sites [5]. A recent report published by the World Health Organization (WHO) that surgical site infection (SSI) is one of the commonly occurring hospital-acquired infections (HAI) in low- and middle-income countries. This affects up to one-third of patients who have undergone a surgical procedure. Although SSI frequency is lower in developed countries, it remains the second most common type of HAI in the USA [6].

In the Kingdom of Saudi Arabia, several studies found the incidence of surgical site infections ranges from 6.8% to 24% [7-9]. Several studies have been done to assess the SSI of the particular site such as the ankle, breast, and more [10, 11]. The infection in a surgical wound is an indication of the disrupted host-microorganism equilibrium that leads to colonization of the bacteria on the surgical site. As a result, the wound healing process is greatly affected, and systemic response also will manifest [12].

The consequences and impact of postoperative wound infections have been published exhaustively all over the world that included an increase in morbidity, mortality, and increase in the duration of hospital stay. This SSI also leads to readmission of the patients, failure of primary surgical methods, and so on. This increasing incidence of SSI also impacts an additional burden on health care expenditure and the need for additional resources [13-15]. This leads to a further increase in the pressure on health care systems which is already overburdened due to the coronavirus – 19 (COVID-19) pandemics, especially in developing countries [16, 17]. Hence, it has become more important to understand the epidemiology, causative organisms, and risk factors for the SSI for the prevention of SSI.

In most post-operative infection cases, the causative organisms are endogenous in origin; the commonly found in SSI clinical isolates are Staphylococcus aureus, enterococci, E.Coli and coagulase-negative staphylococcus. Some studies have found that methicillin-resistant staphylococcus (MRSA) was also responsible for SSI [18, 19]. This scenario further makes things complicated as MRSA organisms are difficult to treat. In the past, some of the authors have made attempts to find the different risk factors for postoperative infections and commonly reported factors are the long duration of surgery, improper pre-operative preparation of the skin, type of surgery, impaired physiological states such as hypoxia, hypothermia, shock and associated co-morbid conditions (diabetes mellitus, obesity, and immune deficiency) [20-22]. Some of the authors in the past have attempted to do systematic reviews on the SSI; but with our extensive review of literature, there are limited systematic reviews available that cover the epidemiological characteristics and risk factors [23, 24]. Hence, this systematic review was planned to find the epidemiological features, prevalence, causative organisms, and predisposing risk factors for the development of postoperative infections among surgical patients of all the six WHO regions.

MATERIALS AND METHODS

The present systematic review was made as per the Preferred Reporting Items for Systematic Reviews (PRISMA) reporting statements and guidelines.

Search Methods and Inclusion Criteria

The research team made extensive literature searches from PubMed/Medline, Cochrane Library, Embase, and Database of Abstracts of Reviews of Effects (DARE). The search methods involved the keyword "post-operative infection," "surgical site infection," "prevalence of surgical site infection," "incidence of surgical site infection," "risk factor," and "causative organism". Firstly, articles published in the English language are only included and other language articles are excluded. The article was published during the last ten years; all the surgical specialties (including dental science) were included in the present review. Also, those articles must have been published in a peer-reviewed journal with an International Standard Serial Number (ISSN).

Data Extraction

All the authors have collected the articles as per the inclusion criteria. After the collection and compilation of articles, two independent authors (first and second) reviewed and included articles for data extraction and synthesis. The extracted data is initially screened based on title and abstract and then eligible articles were further assessed for data extraction. The extracted data include types of study design, sample size, prevalence, potential risk factors, and causative microorganisms. The potential risk factors evidence was synthesized based on p-value and/or odds ratio (OR), while other data were synthesized based on frequency and proportion.

RESULTS AND DISCUSSION

The below figure (PRISMA flow chart) summarizes the data extraction process for this systematic review. The number of articles included and excluded in the different stages based on the data extraction criteria is described. These articles are published in peer-reviewed journals during the past 10 years. Initially, there were around 282 articles were identified in this review. Subsequently, after exclusion from each stage, a total of 18 full-text articles were assessed for evidence synthesis.

Table 1 describes the general characteristics included in this review in terms of WHO regions, types of study designs, and types of surgery. The present study included 4 (22.2%) articles from the Southeast region and 61.1% included articles were based on elective surgical procedures.

Study description, major outcomes including the prevalence of SSI in different regions of the world are presented below table. A minimum of one article is selected from each of the six WHO regions. In general, the occurrence rate of SSI ranges from 2% to 17.8%. Regarding causative organisms, three microorganisms are commonly reported in most of the studies were Staphylococcus aureus, Klebsiella pneumonia, and E.Coli. Among the different procedures reviewed, incidence and prevalence rates were higher among emergency surgical procedures and lower among obstetrics and gynecology procedures (Table 2).

Table 3 potential risk factors for the development of SSI in the different study populations. The study included finding that associated risk factors were reviewed based on their p-value and/or odds ratio (OR) with the 95% confidence interval (CI). The OR value of more than one and 95% CI value does not include a null value of one is considered as a positive association. The higher the confidence interval indicates the strength of association is higher. In general, longer preoperative duration stay in the hospital, decreased Hb and serum albumin level, comorbid conditions such as diabetes, hypertension are potential risk factors for the development of SSI.