Antibiotics are considered one of the greatest medical discoveries (Moser et al., 2019). Their history dates back to 1928, when natural penicillin was discovered (Grayson, 2010). The widespread use of antibacterial drugs is due to their broad spectrum of action. Despite advances in medicine, antibiotics remain the first-line treatment for infectious diseases (Baran et al., 2023). Proper use of antibiotics saves millions of lives each year, preventing complications. However, infections still cause numerous deaths, even in developed countries with unrestricted access to antibiotics (Moser et al., 2019). Since the discovery of penicillin, many antibacterial drugs have been introduced, but the effectiveness of treating bacterial infections has been steadily decreasing. This phenomenon is caused by factors such as improper antibiotic selection for patients, incorrect dosing that hinders the achievement of therapeutic concentrations at the site of infection, and the failure to update knowledge about antibiotics, their mechanisms of action, and pharmacotherapy (Grayson, 2010; Bradley, 2018). Modern antibiotic therapy presents a significant challenge for both clinicians and microbiologists due to the growing antimicrobial resistance of pathogens. As a consequence, there are frequent therapeutic failures and rising treatment costs (Woroń, 2020; Sapilak, 2020). Microbial resistance to antibiotics poses a serious threat to the control of infectious diseases. Despite the growing demand for new therapies, the development of new antimicrobial drugs has significantly slowed, mainly due to high costs and the limited profitability of the market (Hatfull, Dedrick, and Schooley, 2022). Among infections that present a significant clinical challenge, urinary tract infections (UTIs) draw particular attention. First documented in ancient Egypt in 1550 BC, they continue to be among the most common bacterial infections worldwide. UTIs affect nearly 150 million people annually worldwide, with an annual incidence of 12% in women and 3% in men (Kuo and Jhang, 2017). UTIs affect patients of all ages and are one of the leading causes of morbidity and mortality among the old adults, accounting for 15.5% of hospitalizations and 6.2% of deaths among people aged 65 and older (Zalewska-Piątek and Piątek, 2020; Flores-Mireles et al., 2015; Cassini et al., 2016; Dubbs and Sommerkamp, 2019). UTIs can be caused by various bacteria and fungi. The most common pathogen is uropathogenic Escherichia coli (UPEC), responsible for both complicated and uncomplicated urinary tract infections (Zalewska-Piątek and Piątek, 2020; Trześniewska-Ofiara et al., 2022; Neugent et al., 2020). Other frequently encountered microorganisms include Klebsiella pneumoniae, Enterococcus faecalis, and Proteus mirabilis. Public perception of UTI treatment is that it is an easily treatable condition with antibiotic therapy (Foxman, 2014; Waller et al., 2018). However, problems remain with the chronic nature of these infections, their recurrent character, numerous complications, and rising treatment costs due to increasing resistance in uropathogens (Zalewska-Piątek and Piątek, 2020; Trześniewska-Ofiara et al., 2022; Gaitonde, Malik, and Zimmern, 2019). In recent years, the number of antibiotic-resistant pathogens has increased significantly, making the development of new methods for treating UTIs one of the priorities of modern medicine (Chegini et al., 2021). Urinary tract infections can lead to pyelonephritis and life-threatening urosepsis. Some cases of recurrent UTIs can persist for years and, due to antimicrobial resistance, may require bladder removal (Flores-Mireles et al., 2015; Neugent et al., 2020). This issue requires further research and the development of new therapeutic strategies to effectively address the growing challenges of treating urinary tract infections.

The aim of this study was to analyze the frequency of antibiotic resistance among uropathogens in urinary tract infections in hospitalized patients at the Mazowieckie Specialist Hospital (MSH) in Radom (Poland) in the years 2020–2021.

This study utilized data obtained from the Mazowieckie Specialist Hospital (M.S.H.) in Radom, Poland. The analysis covers the period from 1 January 2020, to 31 December 2021. The data consist of results from urine culture tests performed at the Laboratory Diagnostics Department of M.S.H. for samples submitted by patients hospitalized during the study period. The diagnostic criterion for urinary tract infection (UTI) was the presence of clinical symptoms, with the final diagnosis made by the attending physician. Common symptoms observed in patients included dysuria, nocturia, and pyuria.

At the Laboratory Diagnostics Department, urine samples collected for microbiological testing were cultured using the Hoeprich method on two types of media: blood agar with 5% sheep blood and MacConkey agar. Disposable plastic inoculating loops with capacities of 0.01 mL and 0.001 mL (for 10² and 10³ dilutions, respectively) were used for inoculation. The cultures were incubated at 35°C–37°C for 24–48 h. The results were reported as the number of microbial cells grown per 1 mL of urine. The microbiological criterion for diagnosing a UTI was bacteriuria of ≥10⁴ CFU/mL.

The next step involved the identification and antimicrobial susceptibility testing of pathogenic microorganisms using the Phoenix M50 system by Becton Dickinson. In some cases, additional E-Test strips on Mueller-Hinton agar were used to verify antimicrobial resistance in uropathogens or to explore alternative therapeutic options.

During the analyzed period, the hospital had 613 beds spread across 21 departments and sub-departments. Data were collected from 20 of these departments, including: Clinical Department of Internal Medicine I, Clinical Department of General Surgery, Clinical Department of Oncological Surgery, Clinical Department of Oncology, Clinical Department of Neurology, Clinical Department of Otolaryngology, Clinical Department of Rehabilitation, Clinical Department of Pediatrics, Obstetrics and Gynecology Department, Trauma and Orthopedic Surgery Department, Cardiology Department, Hematology Department, Pulmonology and Pulmonary Oncology Department, Intensive Care Unit, Rheumatology Department, Internal Medicine II Department, Clinical Neurosurgery Department, Pediatric Surgery Department, Cardiac Surgery Department, Neonatology Department, and Ophthalmology Department. Data from the Emergency Department were excluded from the statistical analysis due to the short length of patient stays in that department.

The study was conducted with the approval of the Bioethics Committee of the University of Technology and Humanities (KB/17/2022) on 10 May 2022.

There were 31,635 hospitalisations in 2020 and 32,721 in 2021 at the analysed hospital wards. Urinalysis was performed on 1,885 patients in 2020 and 2,032 patients in 2021. Among patients with a urinalysis performed in 2020, 351 (18.62%) had a urinary tract infection. Among patients who had a urinalysis performed in 2021, 236 (11.61%) had a urinary tract infection. There were 2,919 urine tests carried out in 2020 and 2,951 in 2021. Among urine tests performed in 2020, 1,071 (36.69%) urine tests were positive. Among urine tests performed in 2021, 999 (33.85%) urine tests were positive. Moreover, among positive urine tests carried out in 2020, 484 (45.19%) positive urine tests were obtained 72 h after admission to the hospital ward. Additionally, among positive urine tests carried out in 2021, 444 (44.44%) positive urine tests were obtained 72 h after admission to the hospital ward.

The proper selection of antibiotics for the treatment of infections is crucial for improving clinical outcomes. Any recommendations regarding the dosing of antimicrobial drugs should be applied with great caution, taking into account local epidemiology and patterns of pathogen resistance. Factors such as the severity of the disease, kidney function, coexisting conditions, and the patient’s response to treatment must be considered (Hoff et al., 2020).

Strains isolated from urinary tract infections in patients treated at the Mazovian Specialist Hospital showed varying sensitivity to the antibiotics used. One of the most frequently isolated pathogens was Escherichia coli, which exhibited a higher level of resistance to β-lactam antibiotics compared to aminoglycosides. This observation was also confirmed by other researchers. According to Akselsen et al., E. coli was 88% sensitive to ampicillin, 50% sensitive to gentamicin, and 42% sensitive to third-generation cephalosporins (Akselsen et al., 2022). In Poland, according to data from the National Antibiotic Protection Program (NPOA), the percentage of E. coli isolates resistant to aminopenicillins is high, while resistance to aminoglycosides remains at a lower level. According to NPOA data, in 2017, the resistance of E. coli strains isolated from urinary tract infections in Poland was 69.5% to aminopenicillins and 14% to aminoglycosides (Żabicka, 2018). Similar observations were made in other European countries. According to the 2022 data from the European Antimicrobial Resistance Surveillance Network (EARS-Net), an increase in the percentage of E. coli strains resistant to third-generation cephalosporins was observed in Germany and France, while resistance to aminoglycosides remained at a lower level. In Germany, the percentage of E. coli strains resistant to third-generation cephalosporins was around 10%, while resistance to aminoglycosides remained at about 5%. In France, the percentage of resistance to third-generation cephalosporins in E. coli strains was about 12%, while resistance to aminoglycosides was around 6% (European Centre for Disease Prevention and Control, 2023).

In Middle Eastern countries such as Saudi Arabia, a higher level of E. coli resistance to β-lactams compared to aminoglycosides has also been noted. Studies conducted in this region indicate a significant prevalence of E. coli strains producing extended-spectrum β-lactamases (ESBL), which leads to resistance to penicillins and cephalosporins. At the same time, resistance to aminoglycosides, although present, is less common. A study conducted in Saudi Arabia found that approximately 30% of E. coli strains isolated from urinary tract infections were resistant to third-generation cephalosporins, while resistance to aminoglycosides was about 15%. These data highlight the need for monitoring antibiotic resistance in this region and adjusting empirical therapy for urinary tract infections (Alhazmi et al., 2023).

Despite the limitations in the use of aminoglycosides, such as their potential nephrotoxicity, the lower level of resistance to this group of antibiotics makes them a valuable therapeutic option for urinary tract infections caused by β-lactam-resistant strains (Livermore, 2012).

An analysis of the available data confirms that E. coli strains causing urinary tract infections more often exhibit resistance to β-lactam antibiotics than to aminoglycosides, which is consistent with the results presented in this study.

Research conducted by Ruiz-Lievano and colleagues showed a systematic increase in resistance of Escherichia coli strains to fluoroquinolones in the United States, reaching an alarming level, especially in the context of hospital-acquired infections. This phenomenon is attributed to the extensive use of fluoroquinolones in both human and veterinary medicine, creating strong selective pressure that favors the development of resistant strains (Ruiz-Lievano et al., 2024).

Similar results were obtained in studies conducted in Europe. In the study by Azargun et al. (2020), it was noted that E. coli resistance to fluoroquinolones in urinary tract infections is increasing faster than resistance to β-lactams. The main mechanism underlying this resistance is the mutation of genes encoding DNA gyrase (gyrA) and topoisomerase IV (parC), which code for proteins involved in DNA replication and are the targets of fluoroquinolones (Azargun et al., 2020).

The phenomenon of increased resistance to fluoroquinolones may pose a therapeutic challenge, especially in regions where these antibiotics are often used as first-line drugs for urinary tract infections. Considering the data above, the use of fluoroquinolones should be carefully considered in justified cases, and alternative treatment strategies should be explored, especially in situations where strains are resistant to both classes of antibiotics.

Our own research, which indicates more frequent resistance of E. coli to fluoroquinolones than to β-lactams, aligns with reports from other authors, confirming the global trend of increasing resistance to fluoroquinolones in urinary tract infections.

The scientific literature increasingly supports the high sensitivity of E. coli to fosfomycin, even in strains resistant to β-lactams. A study by Mattioni Marchetti et al. (2023) showed that fosfomycin is effective against E. coli strains producing extended-spectrum β-lactamases (ESBL). Fosfomycin acts on bacteria at a different molecular level by blocking cell wall biosynthesis through inhibition of the UDP-N-acetylglucosamine enolpyruvyl transferase enzyme (MurA), which ensures its effectiveness against strains resistant to other classes of antibiotics (Mattioni Marchetti et al., 2023).

Studies conducted in Europe, including those by Falagas et al. (2016), also confirm the high sensitivity of E. coli to fosfomycin in the treatment of urinary tract infections. In regions where the percentage of E. coli strains resistant to β-lactams is increasing, fosfomycin is becoming an increasingly preferred therapeutic option, especially in outpatient treatment. Moreover, the use of fosfomycin as a single-dose drug for urinary tract infections is considered convenient and effective, which is an additional advantage in treating patients with uncomplicated urinary tract infections (Falagas et al., 2016).

It is worth emphasizing that in countries where fosfomycin is relatively rarely used, resistance to this antibiotic remains low, which makes it still effective against β-lactam-resistant E. coli strains. However, there are already early reports of the development of fosfomycin resistance mechanisms, primarily due to mutations in the murA gene or the presence of specific fosfomycinase enzymes, indicating the need to monitor the use of this antibiotic (Galindo-Méndez et al., 2022).

Additionally, studies by Saeed et al. (2021) also indicate that fosfomycin has a safe profile for use in patients with glucose-6-phosphate dehydrogenase (G6PD) deficiency because its metabolism does not lead to oxidation of red blood cells, which is crucial in this patient group (Saeed et al., 2021).

According to Falagas et al. (2016), fosfomycin can be used in a single dose, which reduces the risk of hemolysis in patients with G6PD deficiency, especially compared to long-term β-lactam therapies, which can pose a challenge in this patient population (Falagas et al., 2016). In the context of patients with G6PD deficiency who require alternative therapies, fosfomycin is a valuable option due to its safety profile and high antibacterial activity (Rodríguez-Gascón and Canut-Blasco, 2019).

Moreover, studies in Europe have shown that fosfomycin exhibits lower levels of resistance among E. coli strains than aminoglycosides. The study by Falagas et al. (2019) suggests that fosfomycin maintains high efficacy, making it an important drug, especially in the context of strains resistant to other classes of antibiotics (Falagas et al., 2019).

Further studies by Sojo-Dorado et al. (2022) confirm the increasing effectiveness of fosfomycin in the treatment of urinary tract infections. The authors emphasize that despite rare cases of fosfomycin resistance, its effectiveness in treating urinary tract infections remains high, which may be due to lower selective pressure compared to aminoglycosides, which are widely used in hospital-acquired infections. This highlights the need for further monitoring of resistance and consideration of fosfomycin as an alternative drug (Sojo-Dorado et al., 2022).

Our own research confirms that E. coli is more often resistant to β-lactams and aminoglycosides than to fosfomycin, which aligns with the literature. These findings have significant therapeutic implications, especially in patients with G6PD deficiency, for whom the use of fosfomycin may be a safe and effective alternative in treating urinary tract infections.

Studies indicate that resistance to aminoglycosides, although observed, develops more slowly in the E. coli population compared to fluoroquinolones. Aminoglycosides act on bacteria by binding to the 30S ribosomal subunit. In the study by Azargun et al. (2020) conducted in Europe, it was shown that E. coli strains causing urinary tract infections exhibit less resistance to aminoglycosides than to fluoroquinolones, which the authors attribute to the lower use of aminoglycosides in outpatient treatment (Azargun et al., 2020).

It should also be noted that the increasing resistance to fluoroquinolones in E. coli presents a serious therapeutic challenge, forcing clinicians to consider alternative options, such as aminoglycosides, especially in patients with uncomplicated urinary tract infections. However, due to potential side effects of aminoglycosides, such as nephrotoxicity and ototoxicity, their use must be carefully considered, and their long-term effects on the patient need to be monitored (Ruiz-Lievano et al., 2024).

The results of our own studies, which show that E. coli strains are more frequently resistant to fluoroquinolones than to aminoglycosides, are consistent with global trends. These findings confirm the need for continued monitoring of fluoroquinolone resistance and consideration of alternative therapies, particularly in the context of urinary tract infections caused by resistant strains.

Aminoglycosides, such as gentamicin and streptomycin, are used to treat enterococcal infections, often in combination with cell wall-targeting antibiotics to achieve a synergistic antibacterial effect. However, their effectiveness is limited due to the resistance mechanisms developed by Enterococcus faecalis. The most common resistance mechanism to aminoglycosides is the blocking of antibiotic binding to its target site, the 30S ribosomal subunit, as a result of the action of aminoglycoside-modifying enzymes (AME). Studies by Arias and Murray (2012) confirm that resistance to aminoglycosides among E. faecalis strains is becoming more widespread, limiting the effectiveness of this antibiotic class in treating urinary tract infections (Arias and Murray, 2012).

In the case of glycopeptides, such as vancomycin and teicoplanin, resistance mechanisms develop more slowly compared to aminoglycosides. Glycopeptides act by disrupting bacterial cell wall synthesis, making them effective against E. faecalis. The literature highlights that resistance to glycopeptides occurs less frequently and is mainly associated with Enterococcus faecium rather than E. faecalis. For this reason, glycopeptides remain a valuable option in the treatment of urinary tract infections caused by resistant E. faecalis strains (Guan et al., 2024).

Additionally, studies by Khalil et al. (2022) suggest that E. faecalis resistance to aminoglycosides is associated with frequent use of these antibiotics in the treatment of hospital-acquired infections, which creates selective pressure favoring the development of resistant strains. In contrast, the use of glycopeptides is often limited to severe infections, contributing to the slower development of resistance to this class of antibiotics (Khalil et al., 2022).

Fluoroquinolones, due to their broad spectrum of activity, have been used in the treatment of urinary tract infections. However, their effectiveness against enterococci is increasingly limited due to rising resistance. A study by Alhhazmi et al. (2024) showed that the use of fluoroquinolones is associated with the selection of resistant E. faecalis strains, and their use as first-line treatment for urinary tract infections contributes to the increase in resistance to these antibiotics (Alhhazmi et al., 2024).

In summary, the results of our own studies, indicating higher resistance of E. faecalis to aminoglycosides and fluoroquinolones compared to glycopeptides, are consistent with current scientific reports. These findings confirm the value of glycopeptides as a therapeutic option in infections caused by multidrug-resistant strains and emphasize the need to monitor resistance to ensure effective treatment of urinary tract infections caused by E. faecalis.

For Enterococcus faecium, the level of resistance to aminoglycosides is often lower than to fluoroquinolones. Studies by Arias and Murray (2012) indicate that resistance to aminoglycosides in E. faecium strains remains stable, partly due to the lower use of aminoglycosides in outpatient treatment (Arias and Murray, 2012).

Further research confirms that in the hospital environment, the use of fluoroquinolones promotes the selection of E. faecium strains resistant to these antibiotics, while aminoglycosides, due to their toxicological limitations, are used more sparingly. Mattioni Marchetti et al. (2023) note that the limited use of aminoglycosides may reduce selective pressure on the development of resistance, thus preserving their efficacy against certain E. faecium strains (Mattioni Marchetti et al., 2023).

The results of our own research, indicating higher resistance of E. faecium to fluoroquinolones than to aminoglycosides, are consistent with current literature reports. They confirm the need for careful use of fluoroquinolones in the treatment of infections caused by E. faecium and emphasize the importance of monitoring resistance, particularly in the context of multidrug-resistant strains.

In contrast to fluoroquinolones and aminoglycosides, resistance to glycopeptides in E. faecium develops much more slowly. The mechanism of glycopeptide resistance is mainly associated with the presence of the vanA and vanB genes, which alter the bacterial cell wall structure, preventing the binding of glycopeptides. In the studies by Arias and Murray (2012), resistance to glycopeptides in E. faecium was clearly lower compared to fluoroquinolones, indicating that the spread of vancomycin-resistant strains is more limited compared to resistance to fluoroquinolones (Arias and Murray, 2012). However, studies by Guan et al. (2024) suggest that while resistance to glycopeptides is significant, it is less common than resistance to aminoglycosides in E. faecium strains (Guan et al., 2024).

In summary, our results indicate that E. faecium strains are more often resistant to fluoroquinolones and aminoglycosides than to glycopeptides, which aligns with findings from other studies. The low levels of resistance to glycopeptides may be due to the more selective use of these antibiotics, especially in severe clinical cases and hospital-acquired infections. Belay et al. (2024) suggest that the controlled use of glycopeptides, limited mainly to cases of multidrug-resistant infections, helps slow the development of resistance among enterococci (Belay et al., 2024).

Resistance of Klebsiella pneumoniae to β-lactams is primarily associated with the production of extended-spectrum β-lactamases (ESBLs) and carbapenemases, which hydrolyze the β-lactam ring, rendering these antibiotics ineffective. Studies by Ramatla et al. (2023) confirm that ESBL- and carbapenemase-producing K. pneumoniae strains are increasingly prevalent in hospital settings, significantly limiting therapeutic options for treating hospital-acquired infections caused by these bacteria (Ramatla et al., 2023).

Further research suggests that the high rates of β-lactam resistance among K. pneumoniae strains result from selective pressure due to the frequent use of β-lactam antibiotics, both in hospitals and outpatient settings. Studies analyzing resistance in different regions of the world highlight that β-lactams remain one of the most commonly prescribed classes of antibiotics for treating bacterial infections, contributing to the rapid development of resistance (Mouanga-Ndzime et al., 2024).

Compared to β-lactams, aminoglycosides, such as amikacin and gentamicin, show higher effectiveness against K. pneumoniae strains. Although resistance to aminoglycosides does occur, it is less frequent and is often the result of enzymatic modification of the antibiotic or changes to the target site. Studies by Yang et al. (2023) demonstrated that in hospital-acquired K. pneumoniae strains, resistance to aminoglycosides is present but develops more slowly than resistance to β-lactams, which may be due to the more restricted use of aminoglycosides (Yang et al., 2023). Additionally, studies by Maraki et al. (2024) indicate that aminoglycosides maintain higher effectiveness against K. pneumoniae compared to fluoroquinolones (Maraki et al., 2024).

The results of our own studies, which show more frequent resistance of K. pneumoniae to β-lactams and fluoroquinolones than to aminoglycosides, align with the latest scientific reports. These findings confirm that the limited use of aminoglycosides may help preserve their effectiveness, making them an important therapeutic alternative, particularly in the context of infections caused by β-lactam-resistant strains. These results emphasize the need for continued research into resistance and the monitoring of antibiotic usage to optimize treatment strategies and reduce the growing resistance.

Studies by Rezaei et al. (2024) and Geetha et al. (2020) showed that resistance to fluoroquinolones is becoming more common in K. pneumoniae strains, especially in hospital settings (Rezaei et al., 2024; Geetha et al., 2020). This increase may be linked to the widespread use of fluoroquinolones as first-line treatments for urinary tract infections and other bacterial infections. Further studies show that fluoroquinolone resistance is more common and develops faster compared to β-lactams, which may result from selective pressure caused by frequent use of fluoroquinolones. Studies by Maraki et al. (2024) suggest that the widespread use of fluoroquinolones, especially in outpatient settings, promotes the selection of fluoroquinolone-resistant strains, while resistance to β-lactams, although significant, develops more slowly (Maraki et al., 2024).

An analysis by Ramatla et al. (2023) suggests that reducing the frequency of fluoroquinolone use in cases where they are not essential could help limit the growing resistance to this drug class (Ramatla et al., 2023).

Fosfomycin remains effective against many K. pneumoniae strains, even those resistant to β-lactams or fluoroquinolones. Its unique mechanism of action makes it a valuable alternative for treating urinary tract infections, particularly in cases of multidrug resistance. In contrast to fluoroquinolones, fosfomycin is less commonly used, resulting in less selective pressure, which helps preserve the drug’s effectiveness. Studies by Leelawattanachai et al. (2020) indicate that fosfomycin remains effective against K. pneumoniae strains producing extended-spectrum β-lactamases (Leelawattanachai et al., 2020).

In summary, our results indicate that K. pneumoniae is more frequently resistant to fluoroquinolones than to β-lactams or fosfomycin, which aligns with the latest scientific reports. These findings emphasize the need for the restricted use of fluoroquinolones and highlight the value of fosfomycin as an effective therapeutic alternative in cases of infections caused by multidrug-resistant strains.

Among Proteus mirabilis strains, resistance to aminoglycosides is primarily due to the presence of aminoglycoside-modifying enzymes (AMEs). These mechanisms lead to the rapid development of resistance to drugs such as gentamicin and amikacin. Studies by Vaez et al. (2022) show that AME enzymes are frequently found in P. mirabilis strains, contributing to the high level of resistance to aminoglycosides in this population (Vaez et al., 2022).

In contrast, β-lactams, which act by inhibiting bacterial cell wall synthesis, remain more effective against P. mirabilis. In this species, β-lactamases are less common or exhibit lower activity compared to the mechanisms responsible for aminoglycoside resistance. Research by ElTaweel et al. (2024) showed that P. mirabilis is more sensitive to β-lactams, especially cephalosporins, suggesting that antibiotics in this class are a more effective treatment option for infections caused by this pathogen (ElTaweel et al., 2024).

It is important to note that the use of β-lactams as first-line antibiotics for treating P. mirabilis infections is supported by their relatively low resistance levels. In contrast to aminoglycosides, which are prone to enzymatic resistance, β-lactams remain effective in a wide range of infections caused by this species. At the same time, studies highlight the need for cautious use of aminoglycosides in treating P. mirabilis infections and recommend monitoring their effectiveness.

Compared to fluoroquinolones, β-lactams have diverse mechanisms of action and are not subject to mutations in the same target genes. Resistance to β-lactams in P. mirabilis is primarily associated with the production of β-lactamases, but these enzymes are less prevalent in hospital strains than mutations leading to resistance to fluoroquinolones. Research by Rubic et al. (2021) confirms that P. mirabilis exhibits lower levels of resistance to β-lactam antibiotics, making them an effective option for treating infections caused by this pathogen (Rubic et al., 2021).

Our own study results show that P. mirabilis is more frequently resistant to aminoglycosides and fluoroquinolones than to β-lactams, which is consistent with the scientific literature. These findings underscore the importance of using β-lactams as the preferred therapeutic option for treating P. mirabilis infections and the need to monitor resistance to aminoglycosides and fluoroquinolones to prevent the development of multidrug-resistant strains.

Pseudomonas aeruginosa strains, due to the extensive use of fluoroquinolones, quickly develop resistance to this class of drugs. In addition to mutations in the gyrA and parC genes, P. aeruginosa may also develop resistance to fluoroquinolones through the activation of efflux pumps, such as MexAB-OprM, which actively expel the drug from the cell, and by reducing the permeability of the outer membrane, limiting the entry of the antibiotic into the cell. Studies by Thompson et al. (2024) and Shariati et al. (2022) demonstrated that these mechanisms are common in P. aeruginosa strains resistant to fluoroquinolones, making this drug class less effective in urinary tract infections (Thompson et al., 2024; Shariati et al., 2022).

The high resistance to fluoroquinolones in P. aeruginosa is of clinical importance because it limits the effectiveness of this drug class in treating infections, especially hospital-acquired ones, which are often caused by multidrug-resistant strains. Therefore, cautious use of fluoroquinolones is recommended, and alternative options, such as β-lactams or their combinations with inhibitors, should be considered to slow the development of resistance.

In the case of β-lactams, such as piperacillin/tazobactam, ceftazidime, or meropenem, resistance in P. aeruginosa develops more slowly and to a lesser extent. The mechanisms of resistance to β-lactams include the production of β-lactamases, such as carbapenemases (e.g., OXA and VIM enzymes), which hydrolyze the β-lactam ring and inactivate the antibiotic. Nevertheless, β-lactams often remain effective against P. aeruginosa, especially when used in combinations that may include β-lactamase inhibitors. Studies by Schwartz et al. (2024) showed that β-lactams retain higher effectiveness against P. aeruginosa compared to fluoroquinolones, making them a valuable therapeutic option for treating infections caused by this pathogen (Schwartz et al., 2024).

Our own research findings, which show that P. aeruginosa is more frequently resistant to fluoroquinolones than to β-lactams, are consistent with other studies. These findings highlight the need for the rational use of fluoroquinolones and continued monitoring of resistance to ensure the effectiveness of therapy against infections caused by P. aeruginosa.

Pseudomonas aeruginosa develops resistance to aminoglycosides through aminoglycoside-modifying enzymes (AMEs); however, the level of this resistance is generally lower compared to fluoroquinolones. Studies by López Montesinos et al. (2022) showed that aminoglycosides, especially amikacin, retain higher effectiveness against P. aeruginosa strains in urinary tract infections. This may be due to the more limited use of these antibiotics and less selective pressure (López Montesinos et al., 2022).

Resistance of Acinetobacter baumannii to β-lactams, including penicillins and carbapenems, is the result of complex mechanisms such as the production of β-lactamases (e.g., OXA carbapenemases), reduced membrane permeability, and activation of efflux pumps. In particular, the production of OXA-type carbapenemases, such as OXA-23 and OXA-58, is commonly found in A. baumannii strains and contributes to high levels of carbapenem resistance, making carbapenems, among the most effective β-lactams for treating multidrug-resistant infections, less useful. Research by Castanheira et al. (2023) showed that A. baumannii strains causing urinary tract infections often exhibit resistance to β-lactams, significantly limiting therapeutic options (Castanheira et al., 2023).

Although A. baumannii can also show resistance to aminoglycosides, especially through enzymatic modification of the antibiotics, the level of this resistance is often lower than that seen with β-lactams or fluoroquinolones. Studies conducted by various research groups suggest that aminoglycosides, particularly amikacin, maintain relatively high effectiveness against A. baumannii strains isolated from urinary tract infections. This may be due to the more limited use of aminoglycosides and less selective pressure compared to fluoroquinolones (Zohar et al., 2024; Gharaibeh et al., 2024; Rafailidis et al., 2024).

In the context of treating A. baumannii infections, especially urinary tract infections, the choice of antibiotics should be based on the results of susceptibility testing. High resistance to β-lactams indicates the need for cautious use of this antibiotic class and consideration of aminoglycosides or combination therapy to enhance treatment effectiveness and prevent further development of resistance.

Resistance of A. baumannii to fluoroquinolones, such as ciprofloxacin and levofloxacin, is the result of several mechanisms. Primarily, this involves mutations in the gyrA and parC genes. Additionally, A. baumannii possesses efflux pumps such as AdeABC, which effectively expel fluoroquinolones from the bacterial cell, contributing to their reduced efficacy. Studies by Aboelenin et al. (2024) and Kherroubi et al. (2024) show that these resistance mechanisms are widely spread among A. baumannii strains, limiting the effectiveness of fluoroquinolones, especially in hospital settings (Aboelenin et al., 2024; Kherroubi et al., 2024).

Research by Scoffone et al. (2025) confirms that in some cases, β-lactams are more effective than fluoroquinolones for treating A. baumannii-caused infections, making them an important therapeutic tool (Scoffone et al., 2025).

In conclusion, the selection of antibiotic therapy in urinary tract infections depends on the specific resistance profile of the pathogen involved. For infections caused by Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Pseudomonas aeruginosa, and Acinetobacter baumannii, resistance to various antibiotic groups, such as β-lactams, aminoglycosides, and fluoroquinolones, poses a significant clinical challenge (Abayneh et al., 2023; Nelson et al., 2024; Murray et al., 2022).

For Escherichia coli and Klebsiella pneumoniae strains, β-lactam antibiotics, particularly cephalosporins and carbapenems, often remain effective, although widespread use of these drugs contributes to increasing resistance, primarily due to β-lactamase production. In strains resistant to β-lactams, fosfomycin demonstrates high efficacy, especially in outpatient treatment and in patients with G6PD deficiency who are at risk of hemolytic reactions from other antibiotics (Romyasamit et al., 2024).

In the treatment of infections caused by Pseudomonas aeruginosa and Acinetobacter baumannii, often multidrug-resistant pathogens, the choice of antibiotics is more limited. P. aeruginosa shows higher resistance to fluoroquinolones compared to β-lactams, making carbapenems and β-lactam combinations with β-lactamase inhibitors more effective therapeutic options (Morris et al., 2019; Zheng et al., 2022). Similarly, A. baumannii demonstrates higher resistance to fluoroquinolones and β-lactams than to aminoglycosides, making the latter a useful alternative, although their use is limited due to potential toxicity (Jeong et al., 2024).

Aminoglycosides such as amikacin and gentamicin remain effective options in the treatment of infections caused by strains resistant to fluoroquinolones and β-lactams, especially Acinetobacter baumannii. However, their use requires caution and monitoring due to the potential nephrotoxic and ototoxic effects (Adeniji et al., 2022; Alqurashi et al., 2022; Rafailidis et al., 2024; Thy et al., 2023).

These data highlight the importance of individualizing therapy based on the results of susceptibility testing, particularly in hospital settings, where there is significant selective pressure that favors the development of resistant strains. Proper antibiotic use, resistance monitoring, and a rational approach to antibiotic therapy can help limit the development of resistance and improve the effectiveness of treatment for urinary tract infections caused by multidrug-resistant pathogens.

In conclusion, the problem of antibiotic resistance in urinary tract infections treated in hospital settings requires a multifaceted approach, including regular resistance monitoring, responsible antibiotic use, therapy individualization, and the search for and use of alternative drugs. These actions are crucial for ensuring the effectiveness of treatment and preventing the further development of resistant pathogens.