Multidrug-resistant (MDR) bacteria present a significant global health threat, complicating the treatment of infections and leading to increased healthcare costs and patient risks [1, 2]. Among these, Pseudomonas aeruginosa is particularly concerning due to its ability to thrive in healthcare settings and its natural resistance to many antibiotics [3]. The overuse and misuse of antibiotics are major contributors to the rise of resistant strains [4], highlighting the need for urgent action in antibiotic stewardship and infection control [5].

Healthcare environments, especially hospitals, are particularly vulnerable to MDR bacteria. High patient turnover, invasive procedures, and the frequent use of medical devices create conditions conducive to the spread of these pathogens [6]. Healthcare-associated infections (HAIs) are especially dangerous for immunocompromised patients, worsening an already critical situation [7]. Effective infection control practices, such as maintaining hygiene and sterilization, are crucial for preventing the spread of these harmful bacteria [8].

In the Middle East, the prevalence of P. aeruginosa infections is alarming, driven by factors such as high rates of chronic diseases and inadequate infection control measures [9]. The misuse of antibiotics further exacerbates the issue, promoting the development of resistant strains [10, 11]. As treatment options for P. aeruginosa are limited by the rise of MDR strains, healthcare providers are increasingly resorting to combination therapy, which involves using multiple antibiotics to enhance effectiveness [12].

Despite the significant impact of P. aeruginosa infections, there is a notable lack of research focused on susceptibility patterns and treatment practices in Jordanian hospitals. This gap in knowledge makes it difficult to develop effective infection control strategies tailored to the region. Therefore, this study aimed to investigate the susceptibility patterns of P. aeruginosa strains, examine infection characteristics, and evaluate the appropriateness of empiric antibiotic therapy. Additionally, the study sought to identify factors influencing 30-day all-cause mortality in patients with P. aeruginosa infections.

A total of 1,484 cases with positive P. aeruginosa isolates were screened, of which 1,274 cases were excluded as they did not meet the inclusion criteria. These include: 459 cases with polymicrobial infections or co-infections, 174 cases were < 18 years of age, 148 cases with inadequate susceptibility testing results, 143 cases with incomplete medical records, 137 cases involved recurrent infections, 118 cases of patients who left the hospital without receiving empiric antibiotic therapy, and 95 cases were treated as an outpatient. As such, a total of 210 cases were included and analyzed (14.1%) (Figure 1).

The study cohort, as shown in Table 1, consisted of 210 patients, with a nearly balanced gender distribution: 106 males (n = 106, 50.5%) and 104 females (n = 104, 49.5%). Approximately one-quarter of the patients were aged 65 years or older (n = 54, 25.7%). Regarding smoking status, 31.9% (n = 67) were current smokers, 7.1% (n = 15) were ex-smokers, and the majority, 61.0% (n = 128) were non-smokers. The majority of patients had public insurance coverage (n = 202, 96.2%), while only a small minority (n = 8, 3.8%) had private insurance.

In terms of health status, 82.9% (n = 174) of the cohort had chronic medical conditions. The most common chronic conditions were diabetes mellitus type II (n = 75, 35.7%), hypertension (n = 74, 35.2%), bronchiectasis (n = 25, 11.9%), and myocardial infarction (n = 21, 10.0%).

The majority of infections were community-acquired (n = 178, 84.8%), while 15.2% (n = 32) were hospital-acquired infections. The primary sites of infection were the respiratory tract (n = 81, 38.6%), skin and soft tissue (n = 48, 22.9%), and urinary tract (n = 40, 19.0%).

Infections occurred most frequently during the winter and fall seasons (n = 61 each, 29.0%). Within the three months prior to infection acquisition, 39.5% of patients (n = 83) had been hospitalized, and 39.5% (n = 83) had received antibiotics. Approximately 6.2% (n = 13) of patients had been exposed to major surgery, and 5.2% (n = 11) had undergone urethral stenting before infection acquisition.

Among the tested P. aeruginosa isolates, nearly half (47.1%, n = 99) were MDR pathogens. Regarding treatment outcomes, 4 patients (out of 210) were lost to follow-up during the 30-day period (discharged against medical advice). Of the remaining 206 patients, the 30-day all-cause mortality rate was 4.9% (n = 10), while 95.1% (n = 196) survived. Detailed information is presented in Table 2.

All patients in the study received empiric antibiotics (n = 210, 100.0%). The number of empiric antibiotics administered varied among patients: 21.0% (n = 44) received one antibiotic, while 44.3% (n = 93) received two antibiotics. In terms of the route of administration, the majority of patients were treated with intravenous antibiotics (n = 206, 98.1%). These findings are summarized in Table 3.

The most frequently used empiric antibiotics were imipenem-cilastatin (55.7%), followed by vancomycin (35.7%), piperacillin-tazobactam (26.7%), and levofloxacin (24.3%) (Figure 2). When evaluating the appropriateness of the prescribed antibiotics, almost one-third of the patients (n = 68, 32.4%) received inappropriate initial antimicrobial therapy. Antibiotic prescriptions by infection type are presented in Table S1.

When evaluating predictors of mortality in patients with P. aeruginosa infection (Table 4), infection localization was significantly associated with 30-day all-cause mortality. Patients with non-localized infections, such as bacteremia and sepsis, were 17.45 times more likely to experience mortality compared to those with localized infections [adjusted odds ratio (AOR) = 17.455, P < 0.001].

When evaluating the relationship between previous medication use and the presence of MDR versus non-MDR P. aeruginosa infections (Table 5), recent antibiotic use is significantly associated with MDR infections (P < 0.001). In contrast, corticosteroid use does not show a significant correlation with MDR infections (P = 0.091). Furthermore, the use of immunosuppressants or chemotherapy is significantly linked to non-MDR infections (P = 0.029).

This study offers an examination of P. aeruginosa infections at a tertiary teaching hospital in Jordan, focusing on clinical profiles, infection sources, antibiotic susceptibility patterns, and management strategies. The study found that the majority of P. aeruginosa infections (84.8%) were community-acquired, which contrasts with the traditional belief that P. aeruginosa is predominantly a hospital-acquired pathogen [13]. The primary infection sites were the respiratory tract (38.6%), skin and soft tissue (22.9%), and urinary tract (19.0%), which is consistent with P. aeruginosa’s preference for moist environments and areas with impaired defense mechanisms [14]. P. aeruginosa can colonize and multiply in hospital water systems such as sinks, showers, and water distribution, leading to biofilm formation. Inhalation of these droplets or direct contact with contaminated water can result in respiratory infections or colonization of the skin and soft tissues [15].

Early empiric therapy for high-risk patients was crucial, with most patients receiving combination antibiotic therapy. Clinicians favored imipenem-cilastatin and vancomycin, reflecting the need to provide broad-spectrum coverage for both Gram-negative and Gram-positive pathogens, especially MDR strains common in Jordan [14]. The study also highlighted concerning resistance patterns, particularly to ciprofloxacin (48.6%) and meropenem (49.8%), which are critical antibiotics for managing severe infections. Notably, colistin demonstrated the highest sensitivity, with only 3.4% resistance, highlighting its role as a last-resort therapy for MDR infections. However, the emerging resistance to colistin, even at low levels, signals a growing concern for its long-term efficacy [16].

Antibiotic resistance in P. aeruginosa was widespread, with 48% of isolates being MDR. These findings align with global trends and mirror those observed in Qatar, where similar resistance patterns were reported, emphasizing the increasing challenge of treating P. aeruginosa infections [17]. This highlights the need for effective antimicrobial stewardship programs to manage and limit the spread of resistant strains. Our study finds that recent antibiotic use is significantly associated with the presence of MDR P. aeruginosa infections. This can be explained by selective pressure, where frequent antibiotic use eliminates non-resistant bacteria, allowing resistant strains to survive and multiply [18]. Additionally, immunosuppressive therapies weaken the immune system, making patients more vulnerable to infections caused by non-resistant bacteria.

Despite the high resistance rates, the study found no significant difference in the 30-day mortality rate between patients infected with non-MDR strains and those infected with MDR strains. This is consistent with other research, which has indicated that MDR strains do not always lead to worse outcomes if treated promptly and effectively [19]. The key predictor of mortality in this study was infection localization, with non-localized infections such as bacteremia and septicemia significantly increasing the likelihood of death. This finding emphasizes the importance of early detection and treatment of systemic infections to improve patient outcomes [20].

The study also found that 32.4% of patients received inappropriate initial therapy, likely due to inadequate coverage of P. aeruginosa or resistance to prescribed antibiotics. This highlights the need for better utilization of antibiograms and rapid diagnostic tools to guide empirical therapy and optimize patient outcomes [21].

This study was conducted within a single tertiary teaching hospital in Jordan, which may limit the generalizability of the results to other healthcare settings. The retrospective design and exclusion of newer antibiotics, such as ceftazidime-avibactam and imipenem-cilastatin-relebactam, from the susceptibility testing may affect the completeness of the resistance patterns observed. Moreover, by restricting the study to hospitalized patients who received empirical antibiotic therapy during their hospital stay, outpatients were excluded. This exclusion may have led to an overestimation of resistance patterns. Consequently, the observed trends likely represented more severe infections requiring hospitalization, making it difficult to generalize the findings to milder cases managed in outpatient settings. Additionally, due to the retrospective nature of the study and incomplete documentation in the medical records, we did not evaluate the effect of empiric antibiotics on patient health conditions, focusing instead on the appropriateness of empiric therapy and 30-day mortality. Furthermore, the exclusion of polymicrobial or co-infection cases limits the understanding of the complexity and severity of infections involving multiple microbes. Future research should include these cases to provide a more comprehensive understanding and improve treatment strategies.