Nosocomial infections become prominent in surgical wards because of surgical intervention and operative procedures. A total of 147 isolates were recovered from 122 patients in the present study over one and a half years.
In this study, the prevalence of SSI was 23.3%, in contrast to previous studies in Addis Ababa 39% [14], Mekelle Hospital 44% [10] in Ethiopia, and 7.3% in Pakistan [15]. The difference in surgical site infection’s magnitude may be due to the type of procedures, surgical setup, and environmental factors. Bacterial isolates were examined for the determination of its categories and antibacterial sensitivity patterns. The present analysis shows that gram-negative bacterial isolates predominate in SSIs; Klebsiella species (26%) is perhaps the most common isolated pathogen followed by Escherichia coli (21%), S. aureus (17%), P. aeruginosa (12%), CoNS (10%), Proteus species (4%), and Enterobacter species (4%). The current findings of the SSI infection-causing pathogenic pattern are different with earlier research in Bahir Dar [8] and Gondar [9, 16], where S. aureus is recorded as the widespread SSI-causing organism [17,18,19]. The reason for the predominancy of gram-negative bacteria might be because most of the infected patients are associated with abdominal surgery, and it is previously reported that gram-negative bacteria are predominantly related to intraabdominal procedures [20]. Findings of this research also indicated that more than 66% of gram-negative rods were resistant to ampicillin. A previous study also indicated that, in Gondar, Ethiopia, ciprofloxacin was effective for more than 90% of gram-negative isolates [9]. However, in the present study, ciprofloxacin was effective for more than 61% of the isolates. This sharp fall in effectiveness may be due to overuse of it as an empiric treatment option for most patients.
Among gram-negative isolates, Klebsiella species, Pseudomonas aeruginosa, and Escherichia coli demonstrated high resistance to most of the antibiotics tested. Eighty-four percent of Klebsiella species, 77% of Pseudomonas aeruginosa, and 61% of Escherichia coli were resistant to multiple antibiotics. Although they are not dependable for empiric treatment, ciprofloxacin and ceftriaxone were relatively useful for most bacterial isolates. This finding was also in agreement with the findings of other studies from Bahir Dar and Gondar, Ethiopia [8, 9, 16].
Resistance towards gentamicin in S. aureus differs globally; in our analysis, moderate resistance (52%) was observed that was greater than just that recorded at the university hospital in Gondar [16]. A higher incidence of methicillin resistance in S. aureus was also recorded in the present study; 36% of S. aureus isolates were methicillin-resistant Staphylococcus aureus (MRSA). The finding was higher than the recent report from Gondar University Hospital within the country (24%) [16], and in Mwanza, Tanzania (18.8%) [18].
In our experiment, gram-negative microbes exhibited higher resistance to widely recommended cost-effective antibiotics like penicillin derivatives, doxycycline, and chloramphenicol. The observed high resistance rate could be attributed because these low-priced antimicrobial agents are simple to administer, relatively inexpensive, and commonly prescribed in the evidential management of different infectious diseases. In order to efficiently treat surgical site infections, the use of such medications must be strictly examined for the therapeutic outcome and must be driven by microbiological tests. In the present study, resistance to the third-generation cephalosporins in gram-negative pathogens was higher, and these findings are similar to many prior reports from the Bahir Dar and Gondar regions of Ethiopia, and other nations [9, 16, 21]. An intensified unnecessary prescribing of ceftriaxone as a surgical prophylactic antibiotic at this referral hospital may be a potential cause for the observed greater resistance. Research on antibiotic usage in the same hospital reported ceftriaxone as the most frequently used injectable medication, with some more than 300 prescriptions each month in the surgical ward itself, as a piece of unpublished information from the hospital drugstore.
Besides, several patients from this study got ceftriaxone as a prophylactic antibiotic to avoid infections at the surgical site, and that may have disrupted the exposure of gram-negative pathogens susceptible to ceftriaxone. Most of the Pseudomonas aeruginosa strains isolated were highly sensitive to ceftazidime and moderately to ciprofloxacin and gentamicin. These findings agree with those studies from Gondar University Hospital [9, 16] and Karachi, Pakistan [15]. The above information demonstrates the ability of these classes of medicines for prescribing to treat Pseudomonas in SSIs.
Limitation of the study
Due to the limited resources, individual characterization of the isolates at the species level like Klebsiella spp., Proteus spp., Enterobacter spp., CoNS, Citrobacter spp., Enterobacter spp. was not possible to be performed.