Microbiological profile and antimicrobial resistance of surgical wound infections in a tertiary hospital in Azerbaijan

Summary

Background

Surgical wound infections are a common healthcare-associated complication and are complicated by antimicrobial resistance, which limits empirical treatment options. Local pathogen and susceptibility data are needed to guide empirical therapy and stewardship in Azerbaijan.

Aim

The aim of this study was to describe the microbiological profile of surgical wound cultures and the antimicrobial susceptibility patterns of recovered isolates in a tertiary hospital in Azerbaijan.

Methods

A retrospective laboratory-based study was conducted from August to December 2024 using surgical wound culture records and susceptibility data. Antimicrobial susceptibility testing was performed by disk diffusion and minimum inhibitory concentration–based methods and interpreted according to European Committee on Antimicrobial Susceptibility Testing criteria.

Findings

Out of 344 surgical wound culture records, 45 had no microbial growth and 299 were analysed. The most frequent micro-organisms were Staphylococcus aureus (84/299, 28.1%), Pseudomonas aeruginosa (54/299, 18.1%), Staphylococcus epidermidis (24/299, 8.0%), Klebsiella pneumoniae (22/299, 7.4%), and Escherichia coli (19/299, 6.4%). Among S. aureus isolates, 13 of 84 (15.5%) were methicillin-resistant S. aureus. All tested S. aureus isolates were susceptible to vancomycin and linezolid. Ps. aeruginosa showed the highest susceptibility to meropenem (90.7%), amikacin (85.2%), and imipenem (82.7%). Among Enterobacterales, carbapenems showed the highest overall in-vitro activity in the tested panels. Of 195 isolates eligible for multi-drug-resistant (MDR)/extensively drug-resistant (XDR) assessment, 93 (47.7%) were MDR, including 8 (4.1%) possible XDR and 2 (1.0%) as confirmed XDR.

Conclusion

Surgical wound cultures were dominated by S. aureus and non-fermenting Gram-negative bacilli. Given increasing resistance, particularly among Gram-negative pathogens and persistent surveillance gaps, these findings support routine culture-based diagnosis and use of local susceptibility data to guide empirical therapy and antimicrobial stewardship.

Introduction

Surgical wound infections, including surgical site infections (SSIs), remain a major component of healthcare-associated infections (HAIs) and continue to impose a substantial burden on health systems worldwide. Despite advances in asepsis, peri-operative care, and antimicrobial therapy, HAIs remain among the most persistent challenges in modern hospitals. Early detection and accurate identification of causative micro-organisms are essential in effective management as they support etiological diagnosis, antimicrobial susceptibility testing (AST), and timely selection of targeted therapy [1].

According to the World Health Organization (WHO), HAIs affect approximately 7 out of every 100 hospitalized patients in developed countries and in 10 out of every 100 patients in developing regions [2]. The etiological agents are frequently opportunistic hospital-associated micro-organisms, characterized by enhanced survival in the healthcare environment and a tendency to develop resistance to antimicrobial agents, antiseptics, disinfectants, and other control measures. Broad and insufficiently controlled empirical antibiotic use further promotes the emergence and persistence of resistant strains. Recent WHO global antibiotic resistance surveillance (GLASS) report surveillance data further indicate that antibiotic resistance remains a major global threat, with increasing resistance trends particularly among Gram-negative bacterial pathogens and disproportionate burden in settings with limited diagnostic and surveillance capacity. Approximately one in six laboratory-confirmed bacterial infections worldwide were caused by antibiotic-resistant bacteria in 2023 [3].

Among the major pathogens involved in surgical wound infection, Staphylococcus aureus remains one of the most important, although SSIs may also be caused by a wide range of Gram-positive and Gram-negative micro-organisms depending on the hospital setting, patient profile, and infection control practices [4,5]. Clinically, these infections are significant because they delay wound healing, prolong hospitalization, increase healthcare costs, and may lead to long-term complications or increased mortality risk.

The origin of SSIs is commonly categorized as exogenous or endogenous. Exogenous infections arise from external contamination related to the hospital environment, staff, instruments, or procedural breaches, whereas endogenous infections originate from the patient’s own flora and become clinically significant when host defences are impaired [6]. The likelihood of infection is influenced by multiple factors, including immune status, the type and severity of the wound, surgical duration and complexity, and medication exposure, including antibiotics [7]. Although individualized clinical decision-making is often required, antibacterial agents remain central to treatment regimens for infectious complications. Antibiotic prescribing rates vary widely across departments and are particularly high in intensive care units, underscoring the need for reliable microbiological support to reduce unnecessary exposure and improve antibiotic selection [8].

The spread of multi-drug-resistant (MDR) and extensively drug-resistant (XDR) pathogens further complicates treatment. Recent international reports continue to emphasize the importance of resistant Gram-negative bacteria (extended-spectrum beta-lactamase–producing Enterobacterales, MDR Pseudomonas aeruginosa, and Acinetobacter baumannii), methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus, and other priority pathogens in hospital-associated infections [[8], [9], [10]]. In surgical practice, these resistance patterns directly affect the effectiveness of prophylaxis and empirical therapy, making local surveillance data and regional susceptibility patterns essential for rational antibiotic selection.

Although the microbiology of surgical wound infections has been widely described internationally, the relative frequency of pathogens and their resistance patterns vary substantially across hospitals and regions. In Azerbaijan, published hospital-level microbiological data on surgical wound infections and local antimicrobial susceptibility patterns remain limited. This evidence gap complicates empirical treatment decisions and weakens antimicrobial stewardship. Therefore, local surveillance data are needed to support microbiological diagnosis, guide empirical antibiotic selection, and strengthen antimicrobial stewardship in tertiary care hospitals. In this context, the present study aimed to describe the microbiological profile of surgical wound isolates and their antimicrobial susceptibility patterns in a tertiary hospital in Azerbaijan.

Methods

Study design, setting, and period

A retrospective, laboratory-based descriptive study was conducted at the Main Clinical Hospital of the Ministry of Defense of the Republic of Azerbaijan. The study analysed microbiological culture records from postoperative wound–related specimens processed between August and December 2024.

Study population and clinical characteristics

The analysis was based on microbiology laboratory records from patients with postoperative wound–related infectious complications following surgical interventions. The available demographic and clinical information included age, sex, and selected clinical characteristics, which were recorded in the laboratory dataset. The dataset contained specimen-level culture records and isolate-level antimicrobial susceptibility results. For descriptive purposes, specimen-level outcomes were categorized as no growth or culture positive, whereas organism frequencies and antimicrobial susceptibility results were summarized at the isolate level. Data on peri-operative antimicrobial prophylaxis and pre-operative S. aureus screening/decolonisation were not available in the laboratory dataset.

Case definition and eligibility

For the purposes of this study, surgical wound infection was defined as a clinically suspected infectious complication at or near the operative site for which a specimen was submitted for microbiological examination after surgery. Eligible records included postoperative wound–related specimens such as deep wound aspirates, tissue biopsy material, abscess content, and other wound-associated samples collected from patients after surgical intervention. Formal Centers for Disease Control and Prevention (CDC)/National Healthcare Safety Network (NHSN) SSI criteria were not applied because this study was based on routine microbiology records, and cases were not independently adjudicated using standardized clinical signs, imaging, operative findings, or follow-up data. Records were excluded if specimens were inadequate for culture because of insufficient volume, gross contamination, improper transport, or delay beyond laboratory acceptance criteria. Records with no microbial growth were retained for specimen-level summaries but were excluded from isolate-level organism frequency and antimicrobial susceptibility analyses. Where a specimen yielded more than one organism, each organism was counted as a separate isolate in isolate-level analyses. Repeated records from the same infectious episode yielding duplicate isolates with the same identification and susceptibility profile were excluded from isolate-level summaries where appropriate.

Specimen collection and transport

Specimens were collected under routine clinical conditions according to the presumed site of infection. These included deep wound aspirates, tissue biopsy material, abscess contents, and wound-associated samples. Samples were collected using an aseptic technique by aspiration, biopsy, or deep swab, depending on the specimen type and clinical feasibility. The specimens were placed in sterile transport media and delivered promptly to the microbiology laboratory. Where possible, one portion of each specimen was used for direct microscopy and the remainder for culture. Where feasible, sampling was performed before the initiation of antimicrobial therapy.

Culture conditions and microbiological identification

Specimens were inoculated onto routine bacteriological media (Liofilchem, Roseto degli Abruzzi, Italy) including nutrient agar, MacConkey agar, Endo agar, blood agar, chocolate agar, Schaedler agar for anaerobic culture where indicated, and Sabouraud Dextrose agar medium. Plates were incubated at 37°C under aerobic and anaerobic conditions for 48–72 h. Micro-organisms were identified using standard microscopic and biochemical methods, supplemented by API systems and the automated VITEK 2 platform (bioMérieux, Marcy-l'Étoile, France) where applicable [11,12].

Antimicrobial susceptibility testing

AST was performed after organism identification using Kirby–Bauer disk diffusion (antibiotic disks: Liofilchem, Roseto degli Abruzzi, Italy) and, where applicable, minimum inhibitory concentration (MIC)–based method (automated MIC determination using VITEK 2). Results were interpreted according to European Committee on Antimicrobial Susceptibility Testing (EUCAST) criteria and reported as susceptible (S), susceptible, increased exposure (I), or resistant (R) [13,14].

Phenotypic resistance characterization

Methicillin resistance in S. aureus was assessed phenotypically using cefoxitin disk diffusion screening test or oxacillin MIC, interpreted according to EUCAST criteria. Isolates classified as MRSA were considered resistant to β-lactam agents, in accordance with standard interpretive guidance. Broad-spectrum beta-lactamase activity among Enterobacterales and non-fermenting Gram-negative bacilli was evaluated phenotypically where performed in routine laboratory practice.

MDR and XDR classifications were performed for S. aureus, Enterobacterales, Ps. aeruginosa, and A. baumannii isolates in accordance with the consensus definitions proposed by Magiorakos et al. [15]. MDR was defined as acquired resistance to at least one agent in three or more applicable antimicrobial categories and XDR as resistance to at least one agent in all but two or fewer applicable categories. Species-specific intrinsic resistance and agents specific to urinary tract infections were excluded because all specimens were wound cultures. MDR isolates with incomplete AST coverage were reported as possible XDR when their observed profiles remained compatible with XDR but definitive confirmation was not possible. Isolates with insufficient AST coverage to confirm or exclude MDR were classified as not classifiable. For repeat cultures yielding the same species, only the first isolate was included. Organisms without established MDR/XDR consensus criteria were excluded.

Data handling and statistical analysis

Data were extracted from laboratory records and entered into a study database and analysed descriptively. Culture records were summarized as no growth or culture positive. Organism distribution and antimicrobial susceptibility results were presented as counts and percentages. No inferential comparative analyses were performed.

Results

A total of 344 surgical wound culture records were reviewed during the study period. Of these, 45 showed no microbial growth, while 299 isolate-level records with identified micro-organisms were included in the microbiological analysis. Because some specimens yielded more than one micro-organism, more than one isolate-level record could originate from the same specimen.

The isolated micro-organisms were dominated by Gram-positive cocci and non-fermenting Gram-negative bacilli. The most frequently recovered organism was S. aureus (84/299, 28.1%), followed by Ps. aeruginosa (54/299, 18.1%), Staphylococcus epidermidis (24/299, 8.0%), Klebsiella pneumoniae (22/299, 7.4%), and Escherichia coli (19/299, 6.4%). Other recovered organisms included viridans streptococci (18/299, 6.0%), Candida spp. (14/299, 4.7%), Corynebacterium spp. (12/299, 4.0%), Proteus mirabilis (10/299, 3.3%), Klebsiella oxytoca (8/299, 2.7%), and group D non-enterococci (8/299, 2.7%). Less frequently isolated organisms included Enterobacter aerogenes and Citrobacter freundii (6 isolates each, 2.0%), A. baumannii (5, 1.7%), Proteus vulgaris (4, 1.3%), Stenotrophomonas maltophilia (3, 1.0%), and single isolates of Edwardsiella tarda and Morganella morganii (0.3% each) (Table I).

Table I.

Distribution of micro-organisms recovered from culture-positive surgical wound specimens

Micro-organism	N	%
Staphylococcus aureus	84	28.1
Pseudomonas aeruginosa	54	18.1
Staphylococcus epidermidis	24	8.0
Klebsiella pneumoniae	22	7.4
Escherichia coli	19	6.4
Viridans streptococci	18	6.0
Candida spp.	14	4.7
Corynebacterium spp.	12	4.0
Proteus mirabilis	10	3.3
Klebsiella oxytoca	8	2.7
Group D non-enterococci	8	2.7
Enterobacter aerogenes	6	2.0
Citrobacter freundii	6	2.0
Acinetobacter baumannii	5	1.7
Proteus vulgaris	4	1.3
Stenotrophomonas maltophilia	3	1.0
Edwardsiella tarda	1	0.3
Morganella morganii	1	0.3
Total	299	100.0

Note: Percentages are based on 299 recovered isolates. Some specimens yielded more than one micro-organism.

Among S. aureus isolates, 13 of 84 (15.5%) were classified as methicillin-resistant (MRSA). All tested S. aureus isolates were susceptible to vancomycin and linezolid, while susceptibility to oxacillin, erythromycin, clindamycin, ciprofloxacin, and gentamicin was lower. S. epidermidis also showed complete susceptibility to vancomycin in the tested panel but showed reduced susceptibility to erythromycin and ciprofloxacin (Table II).

Table II.

Antimicrobial susceptibility of major Gram-positive isolates, percentage susceptible

Micro-organism	N	Penicillin	Oxacillin	Cefoxitin	Erythromycin	Clindamycin	Ciprofloxacin	Gentamicin	Vancomycin	Linezolid
Staphylococcus aureus	84	20.2	84.5	84.5	63.1	63.1	60.7	57.1	100.0	100.0
Staphylococcus epidermidis	24	16.7	–	–	41.7	87.5	54.2	70.8	100.0	–

Note: MRSA was defined by cefoxitin disk diffusion according to EUCAST criteria (13/84 isolates, 15.5%). All oxacillin-susceptible isolates were cefoxitin-susceptible. Dashes (–) indicate agents not tested.

MRSA, methicillin-resistant Staphylococcus aureus; EUCAST, European Committee on Antimicrobial Susceptibility Testing.

Among Enterobacterales, carbapenems showed the highest overall in-vitro activity in the tested panels. In E. coli, susceptibility was highest to meropenem and imipenem, whereas activity of amikacin, gentamicin, and ciprofloxacin was lower. K. pneumoniae showed variable susceptibility across agents, with preserved activity of cefepime and carbapenems but reduced susceptibility to amikacin and gentamicin. Pr. mirabilis remained most susceptible to cefepime, ceftriaxone, meropenem, and ciprofloxacin, whereas susceptibility to imipenem, gentamicin, and amikacin was lower (Table III).

Table III.

Antimicrobial susceptibility of major Enterobacterales isolates, percentage susceptible

Micro-organism	N	Ampicillin	Ceftriaxone	Cefepime	Amikacin	Gentamicin	Ciprofloxacin	Imipenem	Meropenem	Trimethoprim-sulfamethoxazole
Klebsiella pneumoniae	22	–	54.5	86.4	36.4	31.8	68.2	71.4	77.3	63.6
Escherichia coli	19	31.6	63.2	73.7	31.6	15.8	57.9	94.4	100.0	52.6
Proteus mirabilis	10	50.0	80.0	100.0	0.0	10.0	70.0	30.0	80.0	50.0

Note: Dashes (−) indicate organism–agent combinations not reported because of intrinsic resistance or lack of applicable EUCAST interpretation. Susceptibility percentages are based on isolates with interpretable AST results. EUCAST, European Committee on Antimicrobial Susceptibility Testing; AST, antimicrobial susceptibility testing.

Among non-fermenting Gram-negative bacilli, Ps. aeruginosa showed the greatest susceptibility to meropenem, amikacin, and imipenem, while susceptibility to ciprofloxacin, gentamicin, ceftazidime, and cefepime was lower. In contrast, A. baumannii demonstrated limited susceptibility overall, with preserved activity only to colistin and minocycline (Table IV).

Table IV.

Antimicrobial susceptibility of major non-fermenting Gram-negative isolates, percentage susceptible

Micro-organism	N	Ceftazidime	Cefepime	Piperacillin-tazobactam	Amikacin	Gentamicin	Ciprofloxacin	Imipenem	Meropenem	Colistin	Minocycline
Pseudomonas aeruginosa	54	61.1	72.5	75.0	85.2	50.0	63.0	82.7	90.7	81.5	–
Acinetobacter baumannii	5	–	–	20.0	40.0	40.0	40.0	40.0	40.0	100.0	100.0

Note: Dashes (−) indicate organism–agent combinations not reported because of intrinsic resistance or lack of applicable EUCAST interpretation. Susceptibility percentages are based on isolates with interpretable AST results. EUCAST, European Committee on Antimicrobial Susceptibility Testing; AST, antimicrobial susceptibility testing.

Among the 195 isolates eligible for MDR/XDR assessment, 93 (47.7%) were classified as MDR. Of these, 8 (4.1% of all eligible isolates) had profiles compatible with possible XDR, and 2 (1.0%) were classified as confirmed XDR. MDR phenotype, including possible and confirmed XDR profiles, was observed in 34 of 78 (43.6%) S. aureus isolates, 47 of 72 (65.3%) Enterobacterales isolates, 10 of 42 (23.8%) Ps. aeruginosa isolates, and 2 of 3 (66.7%) A. baumannii isolates. The confirmed-XDR isolates comprised one Ps. aeruginosa isolate and one Enterobacterales isolate. A total of 22 isolates (11.3%) were classified as non-MDR. The remaining 80 isolates (41.0%) could not be classified as MDR or non-MDR because the available routine AST panel did not provide sufficient coverage of the applicable antimicrobial categories (Table V).

Table V.

MDR/XDR phenotypes among eligible bacterial isolates

Organism	N∗	MDR, N (%)	XDR, N (%)	Non-MDR, N (%)	NC, N (%)
Staphylococcus aureus	78	34 (43.6)	0 (0.0)	0 (0.0)	44 (56.4)
Enterobacterales	72	47 (65.3)	1 (1.4)	2 (2.8)	23 (31.9)
Pseudomonas aeruginosa	42	10 (23.8)	1 (2.4)	19 (45.2)	13 (31.0)
Acinetobacter baumannii	3	2 (66.7)	0 (0.0)	1 (33.3)	0 (0.0)
Total	195	93 (47.7)	2 (1.0)	22 (11.3)	80 (41.0)

Note: N indicates the number of isolates included in the MDR/XDR assessment. For patients with repeat cultures yielding the same species, only the first isolate was included; 25 repeat isolates were excluded. MDR and XDR were classified according to Magiorakos et al. [15], using EUCAST resistant (R) results for category assignment. The MDR category includes isolates with possible XDR and confirmed XDR profiles. Possible XDR indicates an MDR isolate with a resistance profile compatible with XDR but with incomplete AST coverage preventing confirmation. Possible XDR profiles were identified in 8 MDR isolates: Enterobacterales, 5 of 72 (6.9%); Pseudomonas aeruginosa, 2 of 42 (4.8%); and Acinetobacter baumannii, 1 of 3 (33.3%). NC: not classifiable as MDR or non-MDR because of insufficient AST coverage. MDR, multi-drug-resistant; XDR, extensively drug-resistant; EUCAST, European Committee on Antimicrobial Susceptibility Testing; AST, antimicrobial susceptibility testing.

Overall, the microbiological profile of surgical wound infections in this cohort was characterized by the predominance of S. aureus and Ps. aeruginosa, together with substantial representation of resistant Gram-negative bacilli, particularly K. pneumoniae, E. coli, and A. baumannii.

Discussion

The present study provides hospital-based data on the microbiological profile and antimicrobial susceptibility patterns of surgical wound infections in a tertiary care setting in Azerbaijan. The findings show a pathogen distribution dominated by S. aureus and Ps. aeruginosa, with substantial contributions from other Gram-negative bacilli, including K. pneumoniae and E. coli. This overall pattern is broadly consistent with published data showing that surgical wound infections and SSIs are commonly caused by S. aureus together with hospital-associated Gram-negative pathogens, although the relative frequency of individual organisms varies by hospital, patient population, and local antibiotic use practices [1,2,8]. These findings are relevant in the broader context of HAIs because surgical wound infections are a significant cause of prolonged hospitalization, increased antimicrobial exposure, and additional healthcare costs in tertiary care hospitals. In this setting, the prevalence of S. aureus alongside non-fermenting and Enterobacterales pathogens emphasizes the importance of linking routine microbiological surveillance with infection prevention and antimicrobial stewardship efforts [3].

The predominance of S. aureus is clinically important because this pathogen remains a major cause of wound-related morbidity and is frequently associated with resistance to commonly used antibiotics. In the present study, 15.5% of S. aureus isolates were classified as MRSA. Although MRSA was not the dominant phenotype, its presence is still relevant for empirical therapy because even moderate MRSA prevalence may reduce the reliability of routine anti-staphylococcal β-lactam treatment in selected patients [[16], [17], [18]].

An important finding was complete susceptibility of tested S. aureus isolates to vancomycin and linezolid. This supports the continued role of glycopeptides and oxazolidinones as reliable treatment options for serious Gram-positive surgical wound infections in this setting [14].

The substantial contribution of Gram-negative pathogens, particularly Ps. aeruginosa, K. pneumoniae, and E. coli, is also important. In tertiary care hospitals and settings with higher antimicrobial pressure, Gram-negative bacteria often contribute significantly to surgical wound infections [[8], [9], [10]]. In our study, Ps. aeruginosa showed its highest susceptibility to meropenem, amikacin, and imipenem, whereas susceptibility to ciprofloxacin and gentamicin was lower. This pattern is consistent with the recognized therapeutic challenges posed by Ps. aeruginosa, including its intrinsic and acquired resistance mechanisms. These findings are also consistent with WHO GLASS 2025 data showing that antimicrobial resistance increased in 40% of monitored pathogen–antibiotic combinations between 2018 and 2023, with particularly concerning trends among Gram-negative pathogens [3].

Among Enterobacterales, carbapenems showed greater in-vitro activity than several other tested agents. K. pneumoniae and E. coli showed more favourable susceptibility to carbapenems than to ceftriaxone and aminoglycosides. Although molecular resistance characterization was not performed, these results reinforce the importance of culture-based diagnosis and susceptibility-guided therapy rather than reliance on standard empirical regimens alone [9,10,19,20]. This is particularly relevant in surgical wound infections, where empirical use of cephalosporins may be inadequate if local resistance rates are high. WHO GLASS 2025 similarly stresses that rising resistance among Gram-negative pathogens is narrowing empirical treatment options and increasing reliance on broader-spectrum agents, especially in settings with constrained diagnostic capacity [3].

The recovery of A. baumannii, although limited in number, is also clinically significant. This organism remains one of the most problematic healthcare-associated pathogens worldwide because of its persistence in hospital environments, association with multi-drug resistance, and limited treatment options [9,10,21,22]. In the present study, susceptibility of A. baumannii to most tested antibacterial agents was low overall, whereas all isolates remained susceptible to colistin and minocycline.

The findings indicate a substantial burden of multi-drug resistance among bacterial isolates recovered from wound cultures, with nearly half of eligible isolates meeting the MDR definition or showing a more extensive resistance phenotype. The identification of possible XDR and confirmed XDR isolates is clinically important because extensive resistance may substantially limit available treatment options. These findings support the need for continued antimicrobial resistance surveillance and for broader susceptibility testing when extensive resistance is suspected.

Some recovered organisms, including S. epidermidis, viridans streptococci, Corynebacterium spp., and Candida spp., should be interpreted cautiously as they may reflect colonization, mixed wound flora, or contamination rather than true infection. In particular, S. epidermidis is a common skin commensal, and without specimen-depth stratification, its role as a true pathogen versus a contaminant cannot be confirmed from these data alone. Clinical correlation with specimen type and growth characteristics is therefore required. This limitation is inherent to retrospective culture-based analyses and highlights the importance of careful specimen collection, standardized microbiological methods, and clinical correlation when interpreting laboratory results.

From a practical perspective, the present findings suggest that glycopeptides remain reliable options for serious Gram-positive surgical wound infections in this setting, while carbapenems demonstrated the greatest overall in-vitro activity against several major Gram-negative isolates. In particular, vancomycin retained complete activity against the major staphylococcal isolates, while meropenem and imipenem were among the most active agents against Ps. aeruginosa, E. coli, and K. pneumoniae in the tested panels. Amikacin also showed greater activity than gentamicin for some Gram-negative pathogens, supporting the view that aminoglycosides should not be considered interchangeable in empirical practice. At the same time, the variable performance of some non-carbapenem agents, including selected beta-lactam/beta-lactamase inhibitor combinations, indicates that empirical treatment should be guided by local microbiological data whenever possible rather than by generalized assumptions. However, these findings represent laboratory susceptibility data rather than direct evidence of comparative clinical effectiveness, and local prescribing decisions should continue to be individualized according to patient status, wound characteristics, and microbiological confirmation.

These results have implications for hospital infection control policy beyond empirical treatment. As surgical wound infections are an important subgroup of HAIs, local data on pathogen distribution and resistance can inform the review of peri-operative prophylaxis practices, support targeted infection prevention interventions, and strengthen antimicrobial stewardship strategies in tertiary care settings. In Azerbaijan, where published hospital-level microbiological data are limited, this type of surveillance could be particularly useful in improving prescribing practices and infection control planning.

This study has several limitations. It was a single-centre, retrospective, laboratory-based study, and the findings may not be fully generalizable to other hospitals or regions. Detailed clinical variables such as wound classification, prior antibiotic exposure, surgical speciality, comorbidity burden, and patient outcomes were not available for analysis. The absence of data on peri-operative prophylaxis and S. aureus screening/decolonisation limited our ability to assess their potential influence on pathogen distribution. Resistance mechanisms were inferred from phenotypic susceptibility patterns rather than confirmed by molecular testing. Routine AST panels were incomplete for some isolates. Therefore, 80 isolates could not be classified as MDR or non-MDR, and possible XDR isolates were reported separately from confirmed XDR isolates. Because some specimens yielded more than one organism, specimen-level and isolate-level results required separate interpretation. Formal CDC/NHSN SSI criteria were not applied as cases were based on routine microbiology records without independent clinical adjudication. The study population is therefore clinically heterogeneous, and for organisms commonly associated with colonization or contamination – including coagulase-negative staphylococci, viridans streptococci, Corynebacterium spp., and Candida spp. – the distinction between true infection and contamination cannot be reliably established from laboratory data alone, and clinical correlation is essential.

Despite these limitations, the study provides useful baseline information on surgical wound pathogens and antimicrobial resistance patterns in a tertiary hospital in Azerbaijan, where hospital-level microbiological data remain limited. The predominance of S. aureus together with the substantial contribution of resistant Gram-negative organisms highlights the need for continued local surveillance, incorporation of culture data into empirical prescribing, and sustained infection prevention and antimicrobial stewardship efforts. Future studies should include multi-centre data, standardized clinical classification, and more detailed resistance characterization in order to strengthen the evidence base for local treatment guidance and regional policy.

In conclusion, surgical wound infections in this tertiary hospital were microbiologically dominated by S. aureus and Ps. aeruginosa, with additional contribution from Enterobacterales and A. baumannii. The observed susceptibility patterns indicate preserved activity of vancomycin and linezolid against major Gram-positive isolates and relatively strong in-vitro activity of carbapenems against several major Gram-negative pathogens. At the same time, resistance to multiple commonly used agents remains clinically relevant. These findings support routine microbiological investigation of surgical wound infections and the use of local susceptibility data to guide empirical therapy and antimicrobial stewardship.

CRediT authorship contribution statement

Tarana H. Suleymanova: Writing – review & editing, Writing – original draft, Methodology, Investigation, Formal analysis, Conceptualization. Gunduz A. Garayev: Writing – review & editing, Writing – original draft, Methodology, Investigation, Formal analysis, Conceptualization. Hagigat A. Gadirova: Writing – review & editing, Writing – original draft, Supervision, Resources, Methodology, Investigation, Formal analysis, Conceptualization. Ravil M. Huseynov: Writing – review & editing, Investigation, Formal analysis. Orkhan A. Mukhtarov: Writing – review & editing, Investigation, Formal analysis.

Consent to participate

Not applicable.

Consent to publish

Not applicable. The manuscript contains no identifiable patient information.

Ethics statement

This retrospective study used residual diagnostic specimens and de-identified data obtained during routine care. No identifiable information is included and no additional procedures were performed. According to local institutional policy for anonymized retrospective analyses, ethical review and informed consent were not required.

Funding sources

This work received no specific grant from any funding agency.

Conflict of interest statement

None declared.