Discussion

HAIs caused by MDR bacteria represent a worldwide challenge, as they pose serious life-threatening risks. ^{Reference Sandu, Vrancianu and Tantu17} Preventing these infections is therefore a major priority. Achieving effective prevention requires an understanding of local infection rates, the bacteriological profile and associated AMR patterns.

The overall prevalence of HAIs over the three consecutive years (2023–2025) was 10.9%, which is lower than the rate reported during the COVID-19 pandemic in 2020 (14.9%). ^{Reference Ghali, Ben Cheikh, Bhiri, Khefacha, Latiri and Ben Rejeb12} Key strategies include audit and feedback to enhance compliance with best practices, regular staff training, continuous surveillance of HAIs, and Celebration of the World Hand Hygiene Day. Furthermore, established protocols are in place to ensure adherence to standard and contact precautions for patients with MDROs, including the investigation of all reported MDR cases, patient isolation, and reinforcement of hygiene measures. However screening for MDRO in our hospital is not performed systematically due to limited resources. It is mainly carried out when patients are transferred from another healthcare facility to high-risk or critical units such as intensive care, nephrology, and pediatrics.

Globally, HAI prevalence varies considerably between settings. In Africa, a recent meta-analysis including 81,968 patients across 20 countries reported prevalence rates ranging from 1.6% to 90.2%. ^{Reference Bunduki, Masoamphambe, Fox, Musaya, Musicha and Feasey18} In contrast, the European PPS reported a prevalence of 7.1% in 2024. ¹⁹ These disparities may be explained by differences in hospital infrastructure and patient comorbidities. ^{Reference Zhang, Zhang, Wei, Yang, Wang and Yao20} They may also result from variations in HAI definitions, surveillance methodologies, and data collection procedures. ^{Reference Zhang, Zhang, Wei, Yang, Wang and Yao20}

Overall, the burden of HAI in the ICU remains high, with approximately four in ten ICU patients (38.5%) developing at least one HAI. These findings are consistent with reports from other countries, where the prevalence of HAIs among ICU patients ranges from 15.3% to 24.7%. ^{Reference Baklouti, Ben Hmida and Ben Ayed10,Reference Mutair, Alhumaid and Alawi21,Reference Mitchell, Lee and Bartoszko22} This high prevalence may be explained by patients’ increased vulnerability, the severity of their underlying conditions, and the frequent use of invasive devices.

BSIs represented the most common HAI site across all three surveys, in contrast to other Tunisian studies where RTIs ^{Reference Baklouti, Ben Hmida and Ben Ayed10,Reference Ghali, Ben Cheikh, Bhiri, Khefacha, Latiri and Ben Rejeb12} were more prevalent. This observation may be explained by the high device utilization rate (68.9%) observed in our cohort, given the well-established association between vascular devices and catheter-related BSIs. Therefore, strengthening BSI prevention strategies should be prioritized through the implementation of regular audits of practices related to the insertion of central and peripheral vascular catheters in our healthcare settings.

Microbiological documentation was available for 94% of HAI cases, which is higher than proportions reported in previous studies. ^{Reference Letaief, Rejaibi, Hechaichi, Safer, Dhaouadi and Bouguerra5,Reference Zhang, Zhang, Wei, Yang, Wang and Yao20}

Over the three-year period, gram-negative bacteria were isolated three times more frequently than Gram-positive bacteria (72.2% vs 26.2%). Similar patterns have been reported in international studies conducted in China, ^{Reference Zhang, Zhang, Wei, Yang, Wang and Yao20} India, ^{Reference Chakraborty, Sardar and De23} Canada, ^{Reference Mitchell, Lee and Bartoszko22} and Saudi Arabia, ^{Reference Mutair, Alhumaid and Alawi21} where gram-negative bacteria were identified as the leading pathogens responsible for HAIs. Indeed, gram-negative bacteria represent a major therapeutic challenge as they are often associated with severe infections such as pneumonia, BSIs, and UTIs, particularly among critically ill or immunocompromised patients. ^{Reference Bassetti, Peghin, Vena and Giacobbe24}

Klebsiella pneumoniae was the most frequently isolated pathogen across all three surveys, followed by Acinetobacter baumannii, Escherichia coli and Pseudomonas aeruginosa. These findings are consistent with previous Tunisian studies, ^{Reference Baklouti, Ben Hmida and Ben Ayed10,Reference Ghali, Ben Cheikh, Bhiri, Khefacha, Latiri and Ben Rejeb12} in which Klebsiella pneumoniae predominated. Nevertheless, they differ from reports where Escherichia coli was the leading pathogen. ^{Reference Bunduki, Masoamphambe, Fox, Musaya, Musicha and Feasey18,Reference Antonioli, Manzalini and Stefanati25} Such discrepancies may reflect variations in patient characteristics, healthcare practices, and local microbial ecology.

Between 2023 and 2025, MDR bacteria accounted for 41.2% of all isolated pathogens, with no statistically significant change over the study period. This stability may reflect limited changes in antimicrobial stewardship policies or infection control measures during this period across the hospital. Preventive management of MDR-related HAIs may involve cohorting of infected patients, strict adherence to standard precautions, and targeted interventions based on transmission routes. ^{Reference Sandu, Vrancianu and Tantu17}

The proportion of carbapenem-resistant Enterobacterales was 7.9% (10/126). Indeed, since 2006, several carbapenemase-producing gram-negative bacteria, along with different carbapenemase variants, have been reported in Tunisia. ^{Reference Kanzari, Ferjani, Mnif, Mahjoubi, Zribi and Meftah26} Given the limited availability of new antimicrobial agents, continuous monitoring of regional prevalence and resistance profiles is crucial. ^{Reference Kanzari, Ferjani, Mnif, Mahjoubi, Zribi and Meftah26}

At the species level, Klebsiella pneumoniae and Acinetobacter baumannii were the most frequently identified MDR organisms (11.9% each), followed by Escherichia coli (7.1%). These findings are consistent with those of the second national PPS conducted in Tunisia, in which Acinetobacter baumannii accounted for 11.7% of all isolates. ^{Reference Letaief, Rejaibi, Hechaichi, Safer, Dhaouadi and Bouguerra5} Similarly, another Tunisian study investigating long-term trends in MDR gram-negative bacteria between 1999 and 2019 reported a marked increase in carbapenem resistance in Acinetobacter baumannii, with imipenem resistance rising from 34.5% in 2008 to 84.2% in 2019. ^{Reference Kanzari, Ferjani, Mnif, Mahjoubi, Zribi and Meftah26} These findings highlight the growing therapeutic challenges posed by this pathogen in hospital settings.

In multivariate analysis, a prolonged length of hospital stay was identified as an independent predictor of MDR-related HAIs. Prolonged hospitalization is widely recognized as one of the most important risk factors for MDR-related HAIs. ^{Reference Kolbe-Busch, Djouela Djoulako and Stingu27,Reference El Mekes, Zahlane, Ait Said, Tadlaoui Ouafi and Barakate28} This study also revealed that ward type had a statistically significant association with MDR-related HAIs. The ICU showed higher odds for developing MDR infection than other wards. One explanation is that ICUs are generally associated with increased use of broad-spectrum antibiotics, greater exposure to invasive medical devices, and patient vulnerability. ^{Reference Mutair, Alhumaid and Alawi21} Such data can facilitate the design and implementation of effective antimicrobial stewardship programs. It may also help guide the selection of appropriate empirical antibiotic therapy in patients presenting with risk factors of infections.