Introduction

Urinary tract infections (UTIs) are infections caused by the presence, growth and spread of microorganisms in the urinary tract associated with significant morbidity, mortality and health care costs1. It is frequently caused by bacterial pathogens originated from the gastrointestinal tract2. Worldwide, about 150 million people are diagnosed with UTI each year, costing the global economy in excess of 6 billion dollars3,4. In developing countries, including Ethiopia, the facilities for urine culture and antimicrobial susceptibility testing are still not sufficiently available, leading to improper diagnosis and irrational antibiotic treatment of UTI, which accelerates the emergence of multi-drug resistant (MDR) strains.

The emergence of MDR bacterial uropathogens are now a major concern in many parts of the world5. The expansion of global trade and tourism leads to increased potential of MDR bacterial uropathogens to spread all over the world and decrease in export and import of various products affecting the economy of developing countries6. Regarding public health attention, MDR bacterial isolates are described as superbugs having very limited treatment options7.

Both Gram-negative and Gram-positive bacterial isolates can infect the urinary tract of geriatrics. However, by far the most common and resistant agents are the Gram-negative bacilli8. Geriatrics UTIs are caused by wider etiology of MDR bacterial isolates and the infection is characteristically polymicrobial, usually with two to five isolates. Resistant isolates include common uropathogens, such as E. coli, K. pneumoniae, P. mirabilis, Staphylococci, Enterococci, isolates with higher levels of intrinsic resistance, such as P. aeruginosa or P. stuartii, and other bacterial species9.

Urinary bacterial isolates develop resistance to antibiotics in three ways via intrinsic, acquired and adaptative mechanisms, although acquired resistance in common uropathogens may be more frequent in geriatrics10. In urinary tract infected geriatrics several different bacteria like P. mirabilis, P. aeruginosa, and P. stuartiimay form biofilm and camouflage with it. Bacteria within the biofilm survive in a relatively protected environment11. Antibiotics in the urine may not kill bacteria because of its poor diffusion into the biofilms or a reduced metabolic rate of the bacteria resulted in persister bacterial cells12. Persistent bacterial colonization of the geriatric’s urinary tract together with antibiotics exposure without effective killing promotes the emergence of multi-drug resistance13.

Risk factors that increase exposure to MDR bacterial uropathogens in geriatrics includes previous and recurrent UTIs, frequent and prolonged hospitalization, catheterization, antibiotic exposure, immune senescence, co-morbidity, and an increase in the number of geriatric patients due to a rise in life expectancy14,15. Urinary tract infected geriatrics living in long-term-care facilities are an important reservoir of MDR bacterial uropathogens, which can be transmitted to acute care hospitals through inter-hospital transfer13.

Not all UTIs require antibiotic treatment. In cases where microbial isolation is found in catheterized urine samples, simply replacing the catheter may suffice. Antibiotic treatment should only be considered if the patient exhibits UTI symptoms (such as dysuria, fever, or loin pain) and if the same organism is confirmed in blood cultures13,15.

General principles for the management of MDR UTI in geriatrics are ensuring that there is an indication for antimicrobial therapy, obtaining a urine specimen for microbiological documentation of the infecting organism and resistance testing before initiation of antimicrobial therapy, limiting the use of empirical therapy, if possible, by awaiting culture results before instituting therapy, and reassessing empirical therapy once culture results are available16,17. Additional considerations include the local or institutional prevalence of resistant uropathogens and the experience of the individual patient with prior antimicrobial therapy. When empirical therapy is used in a setting where there is an increased likelihood of resistant bacteria, a broader spectrum antimicrobial is usually selected. But it will also contribute to the larger problem of promoting multi-drug resistance4.

Multi-drug resistance is a silent tsunami, so antibiotic stewardship (ASPs) from geriatric patients, health care workers, scientists, industries, and policy makers are needed18. Geriatrics who have UTI should avoid self-medication, misuse, overuse, frequent use, leftover drugs, and sharing. They should complete the treatment course even if they feel better13. Scientists and industries need to promote the development of novel drugs and new diagnostic techniques, like bacteriophage therapy19. Health care workers should diagnose empirically if the patients are in emergency situation. However, definitive diagnosis with culture and antibiotic resistant test for acute patients and review for critical patients. Policymakers must organize awareness programs and pass laws to restrict the sale of unprescribed drugs18,20.

Antimicrobial resistance was ranked fifth among the top ten threats to global health by the WHO report in 201921. It is a serious public health issue that puts the huge population at risk of cross resistance even though they have not been exposed. The global spread of MDR bacteria has resulted in an increase in difficult-to-treat geriatric UTIs. Misuse and overuse of broad-spectrum antibiotics in urinary tract infected geriatrics creates selective pressure that facilitate the emergence of resistant bacterial isolates to the most routinely used antibiotics20,22. The spread of emerging strains can be minimized by raising awareness and reporting findings regularly. Therefore, this study was performed to determine the burden of multi-drug resistant bacterial isolates and their associated risk factors among UTI-confirmed geriatrics in Gondar town.

Materials and methods

Study design, period, study area, and population

A prospective cross-sectional study was conducted from May 1 to July 14, 2022 at the University of Gondar Comprehensive Specialized Hospital, and Kallen Bnakafl and Menna Geriatrics Support Centers Clinics. Both the hospital and geriatrics support centers are located in Gondar town, Amhara regional state, Northwest Ethiopia, situated at 742 km from the capital city of Ethiopia, Addis Ababa. The hospital is a tertiary level teaching and referral hospital catering more than 500 beds for inpatients and rendering referral health services for more than 5 million inhabitants in Northwest Ethiopia. Kallen Bnakafl and Menna Geriatrics Support Centers Clinics provides care and support for more than 110 versus 200 geriatrics permanently within the centers and for more than 100 versus 160 geriatrics outside the center, respectively. All geriatric patients who attended at the University of Gondar Comprehensive Specialized Hospital and lived in Kallen Bnakafl and Menna Geriatrics Support Centers were used as the source population while all UTI-confirmed geriatrics admitted at the University of Gondar Comprehensive Specialized Hospital and attended in Kallen Bnakafl and Menna Geriatrics Support Centers Clinics were used as the study population.

Inclusion criteria: Geriatric patients admitted to the University of Gondar Comprehensive Specialized Hospital and attending the Kallen Bnakafl and Menna Geriatrics Support Centers Clinics, who presented with urinary symptoms, were diagnosed with a UTI, and provided informed consent, were included in the study.

Exclusion criteria: Geriatric patients with cognitive impairments and those who had used antibiotics in the two weeks prior to or during the data collection period were excluded.

Study variables: The dependent variable was prevalence of multi-drug resistant bacterial isolates whereas the independent variables were previous history of UTI, recurrent UTI, catheterization, antibiotic use without prescriptions, diabetes Miletus, and frequent hospitalization of UTI-confirmed geriatrics.

Operational definitions

Geriatricwas defined as age group equal and above 65 years23. UTI-confirmed geriatrics were defined as those geriatrics having significant bacteriuria from microbiological analysis of urine in the hospital adult wards (C and D) and geriatric support center clinics. Significant bacteriuria was defined as when a properly collected midstream urine specimen shown to contain > 105CFU per ml24. Symptomatic UTI was associated with the patients complaining of dysuria, fever, urgent and frequent urination, flank pain, along with malodorous and/or cloudy urine and the number of bacteria on the urine is greater than 105CFU/ml of midstream urine10. Mid-stream urine was defined as a specimen obtained from the middle part of urine flow that is free of contamination, the pre-urethral area is cleansed and the patient is requested to discard the initial flow of urine before collecting the specimen in a sterile container. Multi-drug resistancewas defined as non-susceptibility to at least one agent in three or more antimicrobial classes25. Extensive-drug resistancewas defined as non-susceptibility to at least one agent in all but two or fewer antimicrobial categories tested for a particular microorganism. (i.e., bacterial susceptibility to one or two antimicrobial classes) in this study22. Pan-drug resistancewas defined as non-susceptibility all to agents in all antimicrobial classes for each bacterium in this study26.

Sample size determination and sampling technique

The sample size was determined by using a single population proportion formula. The proportion was taken at 50%, with 95% of confidence intervals (CI) and 5% of margin error.

$$\:n=\frac{{\left(Z\alpha\:/2\:\right)}^{2}P\left(1-p\right)}{{\left(d\right)}^{2}}$$
$$\:n=\frac{{\left(1.96\right)}^{2}*0.5\left(1-0.5\right)}{{\left(0.05\right)}^{2}}=384$$

Using reduction formula as the total UTI-confirmed geriatric population based on the same period of the last year’s record, estimated population was 440.

$$\:{n}_{f}=\frac{n*N}{n+N}$$
$$\:{n}_{f}=\frac{384*440}{384+440}=205$$

By considering a 10% non-response rate: 205 × 0.1 = 20.5 ~ 21,

\(\:{\text{n}}_{\text{f}}\) = 205 + 21 = 226

Therefore, the final calculated sample size was equal to 226.

Where N is the total population, \(\:{\text{n}}_{\text{f}}\) = the final sample size, Zα/2 = the standard normal deviation, at 95% confidence level = 1.96, the prevalence (p) = 0.5; 1−p = 0.5 and the desired degree of accuracy (d) = 0.05.

A total of 226 study participants having UTI were recruited in the study using systematic sampling technique.

Data collection and laboratory methods

The important socio-demographic and clinical history of the study participants such as age, gender, education level, income status, residence, occupation, history of UTI and antibiotic use, hospitalization, catheterization and presence of comorbidities like history of diabetes were collected by trained nurses using a structured questionnaire via face-to-face interviews with geriatrics. Clean catch mid-stream urine was collected in a sterile screw-capped, wide-mouthed urine cup with prior adequate instruction of the participants.

Culture and bacterial identification

Early morning mid-stream urine sample was collected and transported to Medical Bacteriology Laboratory; inoculated in Cysteine Lactose Electrolyte Deficient (CLED) agar (BIOMARKR Laboratories, India) within two hours and incubated for 18–24 h at 35–37 °C. A 0.001 ml inoculating loop was used to inoculate the urine specimen. Colonies with significant bacteriuria (> 105 CFU/ml) were sub-cultured on MacConkey agar and mannitol salt agar (MSA) for isolation of a single species and further characterization by lactose fermentation on MacConkey agar and mannitol fermentation on MSA. Identification of bacteria was done using colony characteristic, Gram staining, biochemical tests such as triple sugar iron, motility, indole, citrate, urease, lysine decarboxylase tests, and novobiocin antibiotic test.

Antimicrobial susceptibility testing

The antimicrobial susceptibility test of all identified bacterial isolates were performed in vitro according to the criteria of clinical and laboratory standards institute (CLSI) using the Kirby-Bauer disk diffusion method on Muller-Hinton agar (MHA). A loop full of bacteria (3–5 identical colonies) were taken from a pure culture colony and transferred to a tube containing 5 ml of normal saline and mixed gently until it forms a homogeneous suspension. The turbidity of the suspension then adjusted to the turbidity of McFarland 0.5 in order to standardize the inoculums size and swabbed on MHA using a sterile cotton swab. The following antimicrobials were used with their respective concentration: ampicillin (10 µg), amoxicillin-clavulanate (20/10 µg), tobramycin (10 µg), tetracycline (30 µg), ciprofloxacin (5 µg), ceftazidime (30 µg), cefazolin (30 µg), cefotaxime (30 µg), meropenem (10 µg), nitrofurantoin (300 µg) and nalidixic acid (30 µg) for Enterobacteriaceae. For Pseudomonasspecies the antimicrobial disks were gentamycin (10 µg), tobramycin (10 µg), norfloxacin (10 µg), meropenem (10 µg). Whereas, vancomycin (30 µg), norfloxacin (10 µg), penicillin (10 units), cefoxitin (30 µg), trimethoprim-sulfamethoxazole (1.25/23.75 µg), gentamycin (10 µg) and doxycycline (30 µg) were for pathogenic Gram-positive cocci. The criteria used to select the antimicrobial agents were based on both their availability for the management of UTIs and the 2022 CLSI guideline27. The plates then incubated at 37 °C for 18–24 h. Diameters of the zone of inhibition around the discs were measured to the nearest millimeter using a ruler and the isolates classified as susceptible and resistant. Isolates intermediate between susceptible and resistant were considered as resistant28.

Methicillin resistant Staphylococcus aureus detection

A lawn culture of S. aureus was made on the MHA plate and cefoxitin (30 µg) disc applied and incubated at (35–37 °C) for 24 h in ambient air. According to CLSI criteria < 10, 11–12 mm, and > 13 mm were categorized as methicillin resistant, intermediate and susceptible, respectively.

Quality control

The questionnaire was checked for its completeness and validity. It was also assured for its consistency by develop first in English, translated to the local language (Amharic), and then re-translated back to English. The culture media were checked for sterility prior to inoculation by incubating 5% of the newly prepared media at (35–37 °C) overnight. Gram’s staining reagents, culture media, and antimicrobial discs were also assured for their expiry date. Turbidity of the suspension was standardized against 0.5 McFarland standards. All antimicrobial discs and culture plates were stored at recommended refrigeration temperature (2–8 °C). Reference strains of E. coli (ATCC-25922), P. aeruginosa (ATCC-27853), and S. aureus (ATCC-25923) were used to check the performance of the media and antimicrobials.

Statistical analysis

Data was coded, entered into Epi Data version 4.6.0.0 and its completeness and clearance was checked to ensure the validity of all recorded data. Then it was exported to Stata/IC version 14.0 software for analysis. The study population was described by using summary statistics. Texts, tables, and figures were used to present the data. Logistic regression model was used to see the association between each independent and the outcome variable. All variable with P-value < 0.05 in the bivariate analysis were included in the final model of multivariate analysis in order to identify associated factors for the prevalence of MDR UTI. The direction and strength of the statistical association were measured using an odds ratio with a 95% confidence interval. An adjusted odds ratio along with a 95% CI was estimated, and a P-value < 0.05 was considered statistically significant.

Results

Socio-demographic and clinical characteristics of the study participants

In this study, out of the expected 226 study participants, only 204 were eligible and included as study subjects with a response rate of 90.3%. Of which, the highest number 187 (91.7%) of study participants were females and their age was ranged from 65 to 88 years with mean age of (70.6 ± 6.83) SD years. The majority of the participants 129 (63.2%) were in the age group of 65–75 and 158 (77.5%) of them had not get the chance of formal education. Due to their age and health problem, most of this study participants 138 (67.7%) had no a job and 89 (43.6%) of them had no any monthly income. According to their residence, the majority 121 (59.3%) of participants were urban dwellers. The most common symptoms reported in large number of UTI-confirmed geriatrics were dysuria 117 (57.4%), urgency of urine 155 (76%), fever 159 (77.9%), frequency of urination 164 (80.4%), and loin pain 175 (85.8%) in ascending order. However, relatively lower number of UTI-confirmed geriatrics manifested abdominal pain and vomiting each symptoms accounted 100 (49%), and 67 (32.8%), respectively (Table 1).

Table 1 Socio-demographic and clinical characteristics of UTI-confirmed geriatrics. ETB Ethiopian Birr, others types of job farmer, cultural drink (tela, tej and areki) workers and food handler, UTI urinary tract infection.
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Prevalence of MDR and MRSA bacterial isolates of the study participants

The overall prevalence of MDR UTI-confirmed geriatrics in this study was 115 (56.4%) (95% CI: 49.79–58.90). The prevalence of MDR bacterial isolates was 126 (49.6%) (95% CI: 41.79–55.90) and the highest prevalence rate was obtained in both 65 to 75 and 76 to 86 years-old age groups equally of 48 (41.7%) (Fig. 1).

Fig. 1
Fig. 1
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Prevalence of MDR bacterial isolates across various age groups in geriatric patients with confirmed UTIs.

Multi-drug resistant bacterial isolates in females 108 (93.9%) was relatively higher than that of males 7 (6.1%) (Fig. 2). Of the total 204 urine specimens with significant growth, 154 (75.5%) being single growth and 50 (24.5%) being mixed growth with two organisms (Fig. 3). Fifty of two hundred four (24.5%) samples with two bacteria each were isolated, making the number of bacteria isolated to be 254. Out of 23 S. aureus isolates 18 (78.3%) were resistant to cefoxitin (surrogate marker for methicillin resistance).

Fig. 2
Fig. 2
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Comparative prevalence of MDR bacterial isolates in male and female geriatric patients with confirmed UTIs.

Fig. 3
Fig. 3
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Results of bacterial growth in culture media.

From a total of 254 different isolated bacterial uropathogens, 206 (81.1%) were Gram-negative bacilli, and 48 (18.9%) were Gram-positive cocci. Out of the total MDR bacteria isolated, the prevalence of Gram-negative bacteria (GNB) was significantly higher (105 (83.3%) than that of Gram-positive bacteria (GPB), 21 (16.7%). The most frequently isolated MDR bacteria was E. coli 60 (47.6%), followed by K. pneumoniae 24 (19.1%). Other urinary tract pathogens that cause a significant MDR UTI burden includes S. aureus 13 (10.3%), P. mirabilis and S. saprophyticus 8 (6.4%), Pseudomonas spp. 6 (4.8%), P. vulgaris 4 (3.2%) and K. rhinos 3 (2.4%). Out of the total 254 isolates the magnitude of MDR isolates were almost half 126 (49.6%) (Table 2).

Table 2 Distribution of MDR bacterial isolates in UTI-confirmed geriatrics. MDR multi-drug resistant, UTI urinary tract infection.
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Risk factors of the study participants

In bivariate analysis of UTI-confirmed study participants, risk factors for MDR UTI included history of previous UTI, history of recurrent UTI, use of a urinary catheter, history of antibiotic use without prescription, diabetes Miletus, and hospitalization of ≥ 3 days. Among the variables analyzed in bivariate logistic regression, those with a P-value < 0.05 were eligible and entered into multivariate analysis (Table 3).

Multivariate logistic regression modeling revealed four independent risk factors associated with UTI by MDR bacterial isolates: history of recurrent UTI (≥ 2 per 6 months) (AOR = 5.02; CI, 1.15–21.85, P = 0.032) and (≥ 3 per 12 months) (AOR = 6.61; CI, 1.98–22.02, P = 0.002), use of a urinary catheter (AOR = 2.83; CI, 1.98–22.02, P = 0.038), history of antibiotic use without prescription (AOR = 3.36; CI, 1.17–9.68, P = 0.025), and hospitalization of 4 days (AOR = 5.46; CI, 1.01–29.59, P = 0.049) and ≥ 5 days (AOR = 5.61; CI, 1.27–24.83, P = 0.023) (Table 3).

Table 3 Bivariate and multivariate analysis of risk factors associated with multi-drug resistance. AOR adjusted odds ratio, CI confidence interval, COR crude odds ratio, 1 reference category.
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MDR, XDR, and PDR isolates and antibiogram

The antibiotic resistance profile of 254 bacterial isolates were studied. Among the tested bacterial isolates, 126 (49.6%) were MDR, 63 (24.8%) were XDR, and 6 (4.8%) were PDR. Among tested GNB isolates, 105 (51%) were MDR, 63 (30.6%) were XDR, and 6 (2.9%) were PDR respectively. The results of MDR within species showed that the species of P. vulgaris 4 (57.1%), followed by E. coli 60 (55.1%), P. mirabilis 8 (53.3%), K. pneumoniae 24 (52.2%), Pseudomonas spp. 6 (50%), and K. rhinos 3 (30%). Likewise, 6 (40%) of P. mirabilis, 6 (50%) of Pseudomonas spp., 37 (34%) of E. coli, 2 (28.6%) of P. vulgaris, 11 (23.9%) of K. pneumoniae, and 1 (10%) of K. rhinos were XDR isolates. However, there was no MDR, XDR and PDR isolates detected in Citrobacter spp. The only PDR bacterial isolate was attributed to Pseudomonas spp. 6 (50%) (Table 4).

Among GPB isolated, MDR isolates accounted for 21 (43.8%). Within the tested isolates 13 (56.5%) and 8 (32%) of S. aureus and S. saprophyticus were found to be MDR, respectively. However, there was no XDR and PDR isolates detected in the S. aureus and S. saprophyticus bacterial species (Table 4).

Table 4 Bacterial resistance levels in urine samples. MDR multi-drug resistant, PDR pan-drug resistant, R0 sensitive for all classes of antibiotics, R1 resistant for one class of antibiotics, R2 resistant for two classes of antibiotics, R3 resistant for three classes of antibiotics etc., XDR extensive-drug resistant. The Gram-negative bacterial isolates were highly resistant to gentamycin 12 (100%), nalidixic acid 167 (91.8%), ampicillin 144 (79.1%), tetracycline 139 (76.4%), norfloxacin 9 (75%), cefazolin 114 (62.6%), and ceftazidime 108 (59.3%) for the tested isolates but demonstrated low level of resistance to meropenem 27 (13.9%), ciprofloxacin 52 (28.6%), nitrofurantoin 60 (33.0%), tobramycin 72 (37.1%), Amoxicillin-clavulanate 70 (38.5%), and cefotaxime 87 (47.8%). The overall resistance rate was 1061 (48.6%), which means almost half of isolates were resistant to antibiotics tested (table 5).
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Table 5 Resistance profile of Gram-negative bacteria identified from UTI-confirmed geriatrics. AMC amoxicillin-clavulanate, AMP ampicillin, AMR antimicrobial resistance, CAZ ceftazidime, CPR ciprofloxacin, CTX cefotaxime, CZN cefazoline, GEN gentamycin, MRP meropenem, NAL nalidixic acid, NIT nitrofurantoin, NOR norfloxacin, R resistance isolates in %, T total number of tested isolates, TET tetracycline, TOB tobramycin. The Gram-positive bacterial isolates were highly resistant to penicillin 30 (62.5%). However, low level of resistance to gentamycin 5 (22.9%), trimethoprim-sulfamethoxazole 15 (31.3%), doxycycline 11 (33.0%), norfloxacin 16 (33.3%), Vancomycin 18 (37.5%), and cefoxitin 21 (43.8%). Among tested Gram-positive isolates, the drug resistance rate of S. Aureus was higher 65 (40.4%) than S. Saprophyticus 51 (29.1%). The total resistance rate of Gram-positive bacterial isolates was 116 (34.5%) (table 6).
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Table 6 Resistance profile of Gram-positive bacteria identified from UTI patients. AMR antimicrobial resistance, DOX doxycycline, FOX cefoxitin, GEN gentamycin, NOR norfloxacin, PEN penicillin, R resistant isolates in percentage, SXT trimethoprim-sulfamethoxazole, T total number of tested isolates, VAN Vancomycin.
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Discussion

Resistance to multiple antibiotics is a major concern across the globe, which leads to frequent treatment failure and complications29,30. Therefore, strengthen knowledge of antimicrobial resistance through surveillance and research is necessary and now applied by World Health Organization (WHO)20. Age or chronic diseases related immune alteration, the high prevalence of UTI and fear of its complication in geriatric patients encourages the irrational use of antibiotics22,31, especially in the developing world where empirical treatment is common. Knowing the prevalence of drug-resistant bacterial uropathogens among geriatric patients could help the clinicians to improve the wise prescription of antibiotics.

In this study, the overall prevalence of MDR UTI was 115 (56.4%). The prevalence of MDR bacterial isolates was 126 (49.6%). This prevalence was comparable with studies in Saudi Arabia 111 (46.3%)32, Turkey 129 (53.8%)33, and Ethiopia-Gondar 473 (44.1%)20. In contrast, this study reported a lower prevalence than studies in Ghana 25 (80.1%)34, and Hawassa-Ethiopia 102 (80.3%)35. On the other hand, the result of this study was higher than studies done in Nepal 90 (41.1%)36, and German 147 (41.4%)22and 3 (5.5%)8. The variation in prevalence of MDR bacteria could be due to increase in trend of MDR bacteria with time, and difference in study period, target population, MDR definition and the antibiotics tested.

In the present study, among MDR isolates the magnitude of GNB were 105 (83.3%) which was higher than the study documented in Iraq 96 (76.2%)37, and Arba Minch-Ethiopia 66 (50.4%)30. In this study, 63 (30.6%) and 6 (2.9%) of the Gram-negative isolates were XDR and PDR, respectively, which were higher than the study conducted in Indian women patients XDR 11 (12%)26, and in Iraq XDR 5 (4%) vs. PDR 1 (0.8%)37. The reason for this higher resistance might be due to self-medication, non-compliance with medication and sales of the substandard drugs may account for the rise in antibiotic resistance observed in this study. In this study area; there is also high tourist flow, and many of residents have relatives from abroad, which may have an impact on the emergence of MDR GNB in this locality, particularly38.

In the current study, among MDR isolates the prevalence of GPB was 21 (16.7%). Among the isolated MDR GPB, S. aureusrepresents a high drug resistance 13 (61.9%). This result was higher than previous study documented in Ethiopia-Gondar 31 (6.6%)20. Methicillin resistant S. aureus (MRSA) isolates were also found at a higher rate 18 (78.3%) in this study. The high rate of resistance might be due to easy access, self-medication, weak adherence of patients to prescribed antimicrobial agents, and wider availability of empirical treatment in the setting.

Comparatively, this study showed that MDR-GNB 105 (83.3%) were more common than MDR-GPB 21 (16.7%). This pattern was similar with studies reported in Ethiopia-Dessie MDR-GNB and MDR-GPB (42 (73.7%) vs. 15 (26.3%))2, German (140 (95.2%) vs. 7 (4.76%))22, and Turkey (129 (100%) vs. 0 (0%))33. According to this study, XDR-GNB and PDR-GNB (63 (24.8%) vs. 6 (2.4%)) were also frequently reported than XDR-GPB and PDR-GPB (0 (0%) for each), respectively. This might be due to the resistant GNB originated from the patient’s gastro-intestine, which is the frontline exposed to different antibiotics and the constant source of infection, poor hand-hygiene practices after a toilet and before a meal in geriatric patients, and the number of antibiotic choices for GPB is relatively fewer with last resorts.

The predominant MDR bacteria was E. coliisolated from UTI-confirmed geriatric patients indicate high levels of resistance 60 (47.6%) to the commonly used antibiotics. This pattern was similar with studies in India 46 (66.7%)26, and Ethiopia-Gondar 104 (65%)38. The main possible reason might be due to plasmid-mediated transfer of multi-drug resistance among MDR E. coli isolates. Other MDR bacteria isolated were K. pneumoniae 24 (19.1%), S. aureus 13 (10.3%), P. mirabilis and S. saprophyticus (8 (6.4%) for each), Pseudomonas spp. 6 (4.8%), P. vulgaris 4 (3.2%), and K. rhinos 3 (2.4%).

Escherichia coli was also the frequent XDR bacteria isolated at a rate of 37 (58.7%), followed by K. pneumoniae 11 (17.5%), P. mirabilis and Pseudomonas spp. (6 (9.5%) for each), P. vulgaris 2 (3.2%), and K. rhinos 1 (1.6%). However, there was no any Citrobacter spp., S. aureus and S. saprophyticus XDR bacterial isolate reported. The possible reasons may be due to the increasing irrational use of antibiotics, the transmission of resistance genes between people and people or/and animals to people, and consumption of animal products that were treated with antibiotics.

Pseudomonas spp. were the only bacterial species that obey the definition of MDR, XDR, and PDR (6 (100%) for each). And were also the lonely bacterial species detected as PDR in this study. Besides, this bacterium is frequently difficult to treat, most probably due to their intrinsic, acquired and adaptive resistance ability to multiple groups of antibiotics.

The current prioritized lists of bacterial pathogens by WHO, categorized E. coli, K. pneumoniae, Pseudomonas and Proteus spp. identified in our study, as critical or most life-threatening Gram-negative pathogens under surveillance due to their high antibiotic resistance. In particular, S. aureus, K. pneumoniae and Pseudomonas spp. have further been described by the Infectious Diseases Society of America as ESKAPE (E. faecium, S. aureus, K. pneumoniae, A. baumannii, Pseudomonas spp. and Enterobacter spp.) pathogens, frequently associated with MDR39,40. These three ESKAPE pathogens were reported 43 (34.1%) of MDR bacterial isolates therefore, posing a major threat to public healthcare in Ethiopia.

In our study, history of recurrent UTIs (≥ 2 per 6 months) and (≥ 3 per 12 months) were significantly associated (P = 0.032) and (P = 0.002) with the prevalence of MDR bacteria, respectively. This result had a similar pattern with a study in Turkey (≥ 2 per 6 months) (P= 0.001)33. The possible reasons for this finding might be due to prolonged hospitalization, catheterization, lack of new novel antibiotics and the frequent use of antibiotics associated with relapse and reinfection.

In this study, the use of a urinary catheter was one of the independent risk factors for MDR bacteria to emerge. This finding is similar with the studies recorded in Serbia41and by a recollective study in Bulgaria, Greece, Hungary, Israel, Italy, Romania, Spain and Turkey UTI geriatric patients5. From the total of 77 (37.8%) previously catheterized geriatrics, 57 (49.6%) of them were infected by MDR bacteria. This finding reflected that the catheter introduces extraneous more resistant types of bacteria from the environment and/or the patient’s own flora. The possible reasons might be due to previous inappropriate technique of catheter insertion, poor hand hygiene and prolonged catheterization.

History of antibiotic use without prescriptions was one of the most important variables significantly associated (P= 0.025) with the presence of MDR bacterial uropathogens. Out of 127 (62.3%) previous antibiotic users, 87 (75.7%) of them were infected with MDR bacterial uropathogens. Our study reflected that the prior and continuous use of antibiotics correlates with an increase in the prevalence of multi-drug resistance. This might be due to the use of broad-spectrum antibiotics, empirical treatment of geriatric patients before culture and drug resistance test has been done, misuse and overuse of antibiotics which creates selective pressure where antibiotics kill susceptible strains and leave the resistant one to multiply. This finding correlated with the study conducted in Turkey33, and Ethiopia-Gondar38.

The statistically significant association between the presence of MDR bacterial uropathogens and hospitalization of 4 days (P = 0.049) and ≥ 5 days (P= 0.023) could be due to long duration of hospitalization, vulnerability of patients to the hospital environments, and the presence of highly resistant bacteria available in an environment. This finding was in agreement with the study reports in Greece42, and German22.

Limitation of the study

The study did not include obligate anaerobic bacteria, and some bacterial isolates could not be identified at the species level due to limited resources. Additionally, antimicrobial susceptibility testing was conducted solely using the disk diffusion method rather than the more precise microdilution technique.

Conclusion and recommendations

The study reveals a high burden of multidrug-resistant (MDR) bacterial isolates, with Escherichia coli being the most common MDR and XDR pathogen, and Pseudomonas spp. as the only pan-drug-resistant (PDR) isolate. Most MDR isolates showed heightened resistance to tetracyclines, beta-lactams, and quinolones. Independent risk factors included recurrent UTIs, urinary catheterization, antibiotic use, and hospital stays of ≥ 4 days. These findings stress the need for routine diagnostics and antimicrobial susceptibility testing over empiric treatment.

The misuse of broad-spectrum antibiotics without prescriptions exacerbates resistance, reducing treatment efficacy and fostering resistant strains in the population. Healthcare policies should promote accurate diagnoses, prudent antibiotic use, and mitigate risks such as recurrent UTIs, improper catheterization, and prolonged hospitalizations (≥ 4 days). In geriatric patients, MDR prevalence necessitates careful UTI management, with treatment for catheterized patients only when identical organisms are confirmed in urine and blood cultures. Antimicrobial stewardship programs are essential to control MDR spread. Future research should prioritize identifying effective strategies to reduce the risk factors associated with multidrug-resistant (MDR) bacterial uropathogens. Additionally, molecular studies should be conducted to better characterize the diverse MDR bacterial isolates.