Antibiotic resistance pattern of bacterial isolates from cases of urinary tract infections among hospitalized and out-patients at a tertiary health facility in South Western Nigeria


Aim: Urinary tract infections (UTIs) are among the most common human infections with distribution of causative agents and their susceptibility pattern to antibiotics varying from region to region. This study aimed at determining the bacterial uropathogens and their antibiotic resistance profile among patients in a Nigerian tertiary health care facility. Materials and Methods: Appropriate urine specimens (midstream/catheter specimen urine) of all suspected cases of UTI by clinicians were processed in the medical microbiology laboratory for detection of significant bacteriuria. Bacteria uropathogens isolated were identified by standard biochemical tests and antibiotic susceptibility test to eight antibiotics was carried out on them using Kirby-Bauer disc diffusion technique. Methicillin-resistant Staphylococcus aureus (MRSA) was identified by cefoxitin disc diffusion technique and extended-spectrum beta-lactamase (ESBL) producing enterobacteria were detected using double-disc synergy test. Results: Of the total 157 males and 189 females investigated, 35.7% and 66.1% respectively had significant bacteriuria. Escherichia coli was the most commonly isolated bacterial pathogen both among in- and out-patients (52.6% vs. 65.5%). Other isolated organisms were S. aureus (13.4% vs. 19.0%), Pseudomonas aeruginosa (10.3% vs. 2.4%), Klebsiella pneumoniae (7.2% vs. 7.1%) and K. aerogenes (7.2% vs. 1.2%). Resistance rate of uropathogens to antibiotics was higher among in-patients. Resistance rate to ofloxacin, ceftazidime and ceftriaxone was generally very low compared to other tested antibiotics. Multiple resistant bacteria: MRSA and ESBL-producing enterobacteria were detected among both in-and out-patient with no significant difference in isolation rate. Conclusion: There is a need for continuous monitoring of uropathogens and their antibiotic sensitivity profile for evidence-based empirical treatment of UTI. There is an urgent need for the establishment of antibiotic stewardship programs in healthcare facilities in Nigeria.

Keywords: Antibiotic resistance, urinary tract infection, uropathogens

How to cite this article:
Timothy OO, Olusesan FJ, Adesola BO, Temitayo AA, David FO, Ige OO. Antibiotic resistance pattern of bacterial isolates from cases of urinary tract infections among hospitalized and out-patients at a tertiary health facility in South Western Nigeria. Ann Trop Med Public Health 2014;7:130-5
How to cite this URL:
Timothy OO, Olusesan FJ, Adesola BO, Temitayo AA, David FO, Ige OO. Antibiotic resistance pattern of bacterial isolates from cases of urinary tract infections among hospitalized and out-patients at a tertiary health facility in South Western Nigeria. Ann Trop Med Public Health [serial online] 2014 [cited 2017 Nov 14];7:130-5. Available from:

Urinary tract infections (UTI) are among the most common infectious diseases in, both outpatients and hospitalized patients. [1],[2] This could be because the urinary tract is in direct contact with the exterior. [3] A global estimation of yearly episodes of UTI could be in the range of 150 million with a large proportion of the infections being in apparent while some episodes manifest with obvious clinical features. [4] Manifestations of UTIs vary from mild symptomatic cystitis to pyelonephritis and septicemia. [1] Significant morbidity and or mortality may arise from improperly treated UTI. [5] UTI affects all age-groups with variable incidence. The highest incidence mostly occurs in healthy young women who present with symptoms of acute uncomplicated bacterial cystitis or pyelonephritis. Infection rate also increases with age. [6]

 Escherichia More Details coli is the most common pathogen responsible for UTI. [7],[8],[9] both in out-patient and hospitalized patient, whereas Klebsiella pneumonie, Pseudomonas aeruginosa and Staphylococcus aureus are other reported important pathogens. [10] In the laboratory, bacterial infection of the urinary tract is said to exist when a significant number of bacteria, usually greater than 10 5 cells per milliliter of urine, are detected in properly collected mid-stream “clean catch” urine or from a catheter specimen urine. [2]

Resistance of urinary tract pathogens to commonly prescribed antibiotics has increased worldwide. [11],[12] There are also reports of change in the resistance pattern over the last decade leading to serious therapeutic challenges. [5],[13] Since the distribution of these pathogens and their susceptibility to antibiotics varies regionally, [7] and treatment for UTI is usually empirical, it is mandatory that there is an adequate knowledge of the epidemiological characteristics of the pathogens involved and their antibiotic susceptibility patterns. This will help to achieve good therapeutic outcomes and prevent the emergence of drug-resistant bacteria strains.

It is against this background that this study set out to identify the bacteria uropathogens of UTI and their antibiotic resistant pattern among out-patients and hospitalized patients attending Federal Medical Centre (FMC), Ido-Ekiti, a tertiary health facility in South-western Nigeria. It is our belief that the result of this study will show the current trend of antibiotic susceptibility pattern of uropathogens in our setting, a necessary step towards defining locally effective empirical treatment of UTI.

Materials and Methods


The study was carried out at the department of Medical Microbiology and Parasitology, FMC, Ido-Ekiti, a tertiary health centre in South-western Nigeria. This centre is staffed with medical doctors and consultants in Laboratory Medicine, Internal Medicine, Surgery and subspecialties, Pediatrics, Community Medicine, Psychiatry, Family Medicine, and Obstetrics and Gynecology.

Study design and procedure

This prospective study was carried out between January 2010 and December 2010. Appropriate urine specimens of all clinically suspected cases of UTI were processed in the department of medical microbiology laboratory of the study site.

Patients who had used antibiotics within a week prior to the hospital visit and those with large fluid intake shortly before specimen collection were excluded from the study. Verbal informed consent was obtained from all patients or their parents in case of children prior to specimen collection.

Urine samples were examined macroscopically and microscopically. Uncentrifuged urine samples were inoculated onto cysteine lactose electrolyte deficient agar (Oxoid, UK), blood agar (Oxoid, UK) and chocolate agar (Oxoid, UK) plates. Inoculated plates were incubated at 37°C for 18 h. Only inoculated plates with significant bacteriuria and only one bacteria isolate were recruited into the study, while few cases of multiple bacteria isolates from same specimen were considered as contaminants and treated as negative (no isolate). In 11 cases of dual isolates of bacteria and Candida albicans, the significance of bacteria isolate was determined by counting only the bacteria colonies on each plate. The colonies were identified by standard biochemical tests and antibiotics susceptibility of the bacteria was performed using Kirby-Bauer diffusion technique in accordance with Clinical Laboratory Standard Institute criteria, 2006. [14] The following antibiotic disks were tested: Augmentin (amoxicillin + clavulanate (30 μg, REMEL), gentamicin (10 μg, REMEL), co-trimoxazole (25 μg, REMEL), ceftazidime (30 μg, REMEL), ceftriaxone (30 μg, REMEL), nitrofurantoin (300 μg, REMEL), ciprofloxacin (5 μg, REMEL), tetracycline (30 μg, REMEL), ofloxacin (10 μg, REMEL). All Gram-negative bacteria resistant to either ceftazidime or ceftriaxone (15) were screened using double-disc synergy tests (synergy between ceftazidime or ceftriaxone and clavulanate) to detect extended-spectrum beta-lactamase (ESBL) production. Methicillin-resistant S. aureus (MRSA) was detected using cefoxitin disk diffusion test. All MRSA were tested for sensitivity against vancomycin (30 μg, REMEL).

Analysis of results

The results were analyzed using SPSS 15.0 statistical software (Illinois, Chicago); two-tailed Chi-square was used to compare data from in-and out-patients with Yates correction or by Fischer exact test where applicable (in cases of small numbers) and P < 0.05 was considered as significant at 95% confidence level. Data were presented in cross-tabulations, percentages, bar and pie-charts.


Of the total 157 males and 189 females clinically suspected cases of UTI, urine specimens of only 56 (35.7%) males versus 125 (66.1%) females showed a demonstrable significant bacteriuria with a single bacteria isolate per specimen, this gender difference in isolation rate was statistically significant; χ2 = 31.91 P < 0.05 [Table 1].

Table 1: Distribution pattern of patients investigated

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The predominant bacteria isolates in both in-patients and out-patients were E. coli 51 (52.6%) versus 55 (65.5%) and S. aureus 13 (13.4%) versus 16 (19%). Other isolates are P. aeruginosa: 10 (10.3%) versus 2 (2.4%), Klebsiella pneumonia: 7 (7.2%) versus 6 (7.1%) and Proteus mirabilis: 6 (6.2%) vs. 2 (2.4%) [Table 2].

Table 2: Distribution of isolated bacterial uropathogens among in-and out-patients

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The rate of isolation was highest in patients >50 years and those between 16 and 34 among in-patient and out-patient. Among in-patients and out-patients, significant bacteriuria was detected in 47.2% versus 21.3% of patients >50 years and 38.3% versus 59.2% of patients between 16 and 34 years. [Table 3] shows the age-range and frequency of patient with significant bacteriuria.

Table 3: Age distribution pattern of positive isolates

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Resistance of E. coli among in-patients as against out-patients was 31.4% versus 10.9%, and 15.7% versus 1.8% respectively for ciprofloxacin and ceftriaxone. For ofloxacin, ceftazidime and co-trimoxazole, the values were 5.9% versus 3.6%, 3.9% versus 3.7, and 100% versus 63.6% respectively. In the case of S. aureus, resistance was 7.7% versus 6.3% to ceftazidime, 7.7% versus 6.3% to ofloxacin, 15.4% versus 12.5% to ceftriaxone, 23.1% versus 12.5% to ciprofloxacin and 100% versus 75.0% to cotrimoxazole [Table 4].

Table 4: Antibiotic resistance pattern of isolated urinary pathogens

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There was no significant difference in detection rate of MRSA and ESBL among hospitalized and out-patients. Of the isolated S. aureus among in-patients and out-patients, 5 (38.5%) versus 2 (12.5%) were MRSA (χ2 = 1.41, P = 0.23), while four (7.8%) versus two (3.6%) of E. coli (χ2 = 0.27, P = 0.6) and one (14.3%) versus none (0%) of K. aerogenes (χ2 = 1.47, P = 0.225) were ESBL [Table 5]. All MRSA detected were sensitive to vancomycin.

Table 5: The pattern of isolation of multi-resistant MRSA and ESBL producing enteric bacteria among in-and out-patients

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Urinary tract infection is a common health problem worldwide; the epidemiology and antimicrobial resistance pattern of associated bacteria varies from region to region and may differ depending on whether it occurs in the community or in the hospital. Surveillance of bacterial spectrum and resistance pattern of uropathogens is thus very important both globally and at the local level. [15]

This study demonstrated a significantly higher prevalence rate of UTI among female patients compared to male patients, a finding in agreement with results of some earlier studies. [5],[7],[8],[16] The reason for this difference might not be unconnected with the short female urethra and its proximity to the anal orifice greatly predisposing to ascending infection of the urinary tract.

The most common bacteria pathogen isolated in this study among both in-patients and out-patients was E. coli, a finding in agreement with some previous studies indicating E. coli as the commonest bacteria isolated from cases of UTI. [7],[8],[9],[17] A surprising finding was that of S. aureus as the second most frequently isolated bacteria pathogen (13.4% vs. 19.0%) both among in-and out-patients in this study. This is at variance with some studies, [5],[8],[9] that reported higher prevalence of other Gram-negative enteric bacilli such as K. pneumonia and P. aeruginosa in UTI compared to S. aureus.[5],[8],[9] Another Nigerian study, however, had reported a similar pattern of isolated of bacterial uropathogen. [18] The reason for this finding is obscure, although, environmental factors may have important roles to play.

Higher frequency of isolation was demonstrated among females in all age-group except among out-patients with age-range 0-15 and >50 years. Highest infection rate was found in patients >50 years (47.4%) among in-patients, majority of which are males (29/46) and 16-34 years (59.5%) among out-patients majority of which are females (46/50). Similar pattern had been demonstrated by Chedi et al. in Kano, Nigeria, where female patients 21-30 years and male >60 years had highest frequency rate. [19] These findings may not be unconnected with the fact that men with obstructive uropathy and related disorders who are almost always >50 years may have constituted the larger percentage of in-patients, whereas women 16-34 years who are sexually active with or without pregnancy may have dominated the out-patient group; the two groups of patients have higher risk of UTI. Increasing rate of UTI with age was not demonstrated in this study contrary to the known fact that incidence increases with age; this can easily be explained by the nature of this study that is a prevalence study as against incidence study.

As expected, pathogens isolated from in-patients generally showed higher resistance rate compared to those isolated from out-patients to tested antibiotics. Majority of the isolates from in-patients showed a high-rate of resistance to cotrimoxazole, tetracycline, augmentin (amoxicillin + clavulanate), nitrofurantoin, and gentamicin, thus these antibiotics should have no role in the empirical treatment of UTI in our hospital. From the sensitivity results, Ofloxacin should be the recommended empirical treatment of UTI in the hospital setting. Among out-patients, high-rate of resistance was demonstrated against tetracycline, cotrimoxazole, gentamicin, nitrofurantoin, and augmentin. Though ceftazidime, ofloxacin, ceftriaxone and ciprofloxacin showed good activity against these pathogens, only the quinolones antibiotics (ofloxacin and ciprofloxacin) should be used for empirical treatment of UTI in out-patients. The exclusion of the cephalosporins as empirical treatment of UTI should help in prolonging the usefulness of this class of drugs. Similar resistance pattern have been reported in previous studies, [16],[20] while high resistance rate of enterobacteriacea had been reported to ampicillin, amoxyxillin-clavulanic acid and cotrimoxazole in Senegal [21] and Tunisia. [22] It is expected that MRSA and ESBL producing enterobacteria that are multiple-antibiotic resistant should be isolated more frequently among hospitalized patients compared to out-patients. In this study, however, there was no significant difference in the isolation rate between these two categories of patients.

This pattern of antibiotic resistance among uropathogens has serious implications on developing countries such as ours due to increased healthcare cost resulting from increased duration of hospital stay and the search for more ‘high-powered’ expensive antimicrobials. [18] The resistance profile of the bacteria isolated may be attributed to irrational use of antibiotics, practices of self-medication, antibiotics misuse and abuse. Many times, an empirical antibiotic is prescribed for patients presenting with UTI and that ideally should be changed once the antibiotic sensitivity pattern is available. However, as shown by a study by Chukwuani et al., only 4.2% of in-patients had antibiotics prescribed based on sensitivity pattern. [23] In Nigeria, access to antibiotics is not well regulated, and these drugs are sold indiscriminately without prescriptions. A study carried out in the South-Eastern part of Nigeria showed that 57.8% of the patients who bought antibiotics during the study duration were without prescriptions. [24] Another study revealed 46.7% of caregivers gave unprescribed antibiotics to children with diarrhea while a community based study in Kano showed 29.4% of the participants having used antibiotics for self-medication. [25],[26] The benefits of antibiotic stewardship programs (ASPs) include a reduction in inappropriate use of antibiotics, reduction in costs and eventual reduction in the incidence of antimicrobial resistance. [27] Components of ASPs include prospective audit with feedback to prescribers, restriction of antibiotics, guidelines based on local sensitivity pattern and education. [28],[29],[30]


This study reinforces the need for continuous local surveillance of bacterial antimicrobial resistance. There is also a need for a comprehensive ASP in our hospital setting while the public should be educated on the consequences of indiscriminate use of antibiotics. The feasibility of empirical treatment of UTI with ofloxacin for both hospitalized and out-patients should be considered in our setting.

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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/1755-6783.146403


[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]

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