Considering that many studies have not been conducted to evaluate the results of antibiotic resistance treatment in pathogens in the western region of Iran, the present study was conducted with the aim of investigating the frequency of bacterial etiological factors and antibiotic resistance of infections caused by urinary catheters in patients hospitalized in Khorramabad teaching hospitals in 2022 - 2023. Gender is one of the factors that influence urinary tract infections, according to several studies (
20). Similar to the findings of the Mohammadi et al. study (
21), women were more likely than men to have urinary infections (65.20%). The majority of the bacteria in the study by Shirvani et al. (
22) were also isolated from samples provided by women. The urethra's short length, its close proximity to the anus and vagina, and the warm, humid environment of the perineum may be contributing factors to the rise in infections among women (
23,
24). In the present study, the most common urinary pathogens in people were
E. coli (41.20%),
S. saprophyticus (20.80%), and
K. pneumoniae (18.40%).
In studies conducted in other parts of Iran and the world, this microorganism is known as the most common cause of urinary tract infection. The prevalence of this bacterium in the study of Mohammed et al. (
25), which was conducted on 117 samples in Bahrain, was 49.06%. In the study of Mohammed et al. in 2022, which was conducted on 773 samples in Somalia,
E. coli was the most common pathogen (26.3%) (
1). A study by Aktaş and Denktaş was conducted in 2020 with the aim of investigating the results of urine culture and antibiotic sensitivity of
E. coli isolates in Turkey.
E. coli accounted for 48% of the strains in this study, with
Enterococcus coming in at 9%,
Staphylococcus coagulase-negative at 8.3%, and
Klebsiella at 7.6% (
26).
Escherichia coli accounted for 50.6% of the organisms in the Tavanaee Sani and Mehrafarid study conducted in Mashhad. The most frequently occurring organisms were Candida albicans, Pseudomonas aeruginosa, and
K. pneumoniae.
Enterococcus was the most prevalent Gram-positive organism (
27). According to a study conducted in 2020 in Mashhad by Vakilzadeh et al., the most prevalent urinary pathogens in individuals with positive cultures were
E. coli (60.9%),
K. pneumoniae (13.9%), and
Enterococcus (
28). The findings of the aforementioned studies demonstrate that urinary pathogen prevalence varies over time and across geographical locations. However, one thing is certain:
E. coli is the most frequent cause of UTIs in the general population. The prevalence of other pathogens varies amongst studies.
Regardless of the bacterial strains, amoxicillin (59.2%) and ampicillin (53.6%) showed the highest resistance to UTI agents in both sexes in this study, and the findings are consistent with those of Baghani Aval et al. studies in Sabzevar (
19) and Abedi Samakoosh et al. in Quemshar (
29). Osman (
30) also carried out a study in 2019 in Erbil, Iraq, to look into antibiotic resistance in bacteria that were isolated from urine samples of patients who had urinary tract infections. In the above study, the highest resistance to ampicillin, aztreonam, cefazolin, clindamycin, and tetracycline antibiotics was observed, which was consistent with the findings of the present study in terms of ampicillin resistance (
30).
The study's findings about other antibiotics did not agree with ours, and this discrepancy might have been brought about by using different resistance assessment instruments and looking at a different number of antibiotics. For instance, the current study did not look into resistance to clindamycin, tetracycline, cefazolin, or aztreonam. In this study, the lowest rate of resistance in men and women was related to imipenem (11.6%) and then amikacin (17.6%). The results of the present study were consistent with the results of the study by Mohammadi et al. in Sanandaj (
21). Similarly, in the study conducted by Safdari and Ghazvini in Mashhad (
31) and the study conducted by Abdollahi and Mehr Azma (
32) in Imam Khomeini Hospital, Tehran, the least resistance to imipenem and amikacin was reported. In the Tavanaee Sani and Mehrafarid study in Mashhad, the highest level of sensitivity to the antibiotic amikacin was observed (
27).
In the study of Aktaş and Denktaş in 2020, the most effective antibiotics for Harvey
E. coli included imipenem, meropenem, ertapenem, and amikacin. In terms of sensitivity to imipenem and amikacin, these two studies were consistent. However, in the present study, sensitivity to ciprofloxacin and gentamicin was also high, which was not reported in the above study (
26). Considering these similarities regarding the lowest antibiotic resistance compared to amikacin and imipenem, and considering the same drug prescription pattern in different parts of the country, these two drugs can be proposed as the first line of empirical treatment for urinary tract infection. However, among the limitations of using these two drugs, the following can be mentioned: Amikacin may cause decreased kidney function, tinnitus, vertigo, and hearing loss in cases of improper administration (
33). Imipenem can also cause kidney dysfunction and convulsions (
34). Therefore, during administration, the maximum and minimum concentrations of the drug should be carefully monitored.
In this study, over 95% of patients had recently used antibiotics, and the findings indicated a statistically significant association between prior antibiotic use and resistance to amoxicillin, ampicillin, and imipenem (P < 0.05). This issue may explain why the level of antibiotic resistance in various organisms against the studied antibiotics was high. It might be possible to prevent the increasing rate of drug resistance with better and more appropriate use of antibiotics. Numerous studies in different parts of the world have shown that the cause and resistance pattern of urinary infections have changed (
35). Therefore, identifying the bacterial agents that cause urinary infections and using appropriate and effective antibiotics to eliminate them are practical approaches to dealing with these infections and preventing their consequences. A high prevalence of microbial resistance to common drugs increases treatment costs, as the lack of effectiveness of cheaper, commonly used drugs often necessitates switching to more expensive alternatives (
36). This underscores the importance of making informed decisions regarding treatment.
The large variation in antibiotic resistance levels can be attributed to differences in the use of antibiotics for treating the disease in different regions. It is well-known that inappropriate and excessive use of antibiotics leads to bacterial resistance. Reducing the prescription of certain antibiotics can, in turn, reduce resistance. The high rate of bacterial resistance to antibiotics observed in the present study, as well as in other studies conducted in Iran compared to other countries, can likely be attributed to indiscriminate antibiotic prescriptions and self-administration without a doctor’s guidance. To address this issue, measures such as performing microscopic urine examinations and urine cultures, prescribing antibiotics properly based on culture and antibiogram results, and periodically conducting similar research in different times and locations to better understand the epidemiology of urinary infections and the resistance and sensitivity levels of microorganisms to various antibiotics should receive greater attention (
37,
38).
The limitations of this study included deficiencies in the clinical and laboratory data of some patients. In certain cases, researchers were unable to access complete and accurate information for specific individuals, leading to their exclusion from the study.
5.1. Conclusions
The majority of bacterial isolates common in catheter-associated urinary tract infections suggest that amikacin and imipenem are appropriate options for initiating empirical therapy until antibiogram results are available. Given the importance of emerging antibiotic resistance and the changing susceptibility and resistance patterns of bacteria, performing antibiogram testing is essential for the effective treatment of these infections.