SM Journal of Urology

Research Article

Evaluation of Uropathogens in Bladder Outlet Obstruction Secondary to Benign Prostatic Hyperplasia

Patrick Temi Adegun1*, Julius Gbenga Olaogun1 and Michael Simidele Odimayo2


Objectives: Although less than 3% of patients with Catheter Associated Asymptomatic Bacteria (CA-ASB) develop bacterimia with urinary pathogen; risk is 36 times increased with indwelling catheter. This study aimed at evaluating the uropathogens and the antimicrobial susceptibility in men with bladder outlet obstruction due to BPH to create baseline data for active surveillance and empiric antimicrobial regimens.

Methods: Urine cultures from 78 men with urinary retention secondary to BPH were evaluated. Distribution of the bacteria causing catheter associated bacterimia and their antimicrobial susceptibility test results were examined using automated identification and antimicrobial susceptibility testing system.

Results: A large proportion of patients with CA-ASB were older (≥60 years; P=0.02). The prevalence of infection was significantly higher in patients on urethral catheters than those on suprapubic catheters. (P=0.011) There was a high prevalence of micro-haematuria and proteinuria (60.5% and 37.2% respectively). Escherichia coli was the commonest organism found in all age groups. There was increased resistance of organism to the four commonly used urinary tract antibiotics (ampicillin, perfloxacin, levofloxacin and erythromycin). The prevalence of multi-resistance was 10.8%.

Conclusion: In a total of 78 samples, 83.3% showed significant growth of pathogens. A slightly more cases of CA-ASB were recorded among elderly patients (≥65 years; 52.3 %). Nitrofurantoin is recommended as the first drug of choice in this country if not contraindicated.


Catheter Associated Asymptomatic Bacteria [CA-ASB] in patients with indwelling urethral catheter, suprapubic catheter, or intermittent catheterization has been defined as the presence of ≥105 cfu/mL or ≥1 bacterial species in a single catheter urine specimen in a patient without symptoms compatible with UTI [1]. Urinary catheterization is very prevalent in hospitals especially in the initial management of patients with Benign Prostatic Obstruction [BPO] [2].

The duration of catheterization varies from patient to patient and has been reported to be the most important factor for the development of CA-ASB in the developed world [1]. Other notable risk factors include the lack of systemic antimicrobial therapy after catheterization, microbial colonization of drainage bag, blood transfusion, place of catheter insertion and older age among others [3].

There are significant consequences of CA-ASB which are usually associated with an inflammatory response in both short- term and long- term catheterized patients [4].

Although less than 3% of subjects with CA-ASB develop bacterimia with the urinary isolate [4], the risk of bacterimia in men with indwelling catheters in some centers has been reported to increase from 3 to 36 times compared to that of men without an indwelling catheter [5]. In addition, infectious complications that may arise in patients with CA-ASB include urinary catheter blockade, bladder calculus formation, urethritis, abscesses and prostatitis [6]. Non-infectious complications include nonbacterial urethral inflammation, urethral strictures, mechanical trauma, and mobility impairment [7,8].

Considering these sequelae, CA-ASB in a patient with BPO can lead to a major health calamity due to its recurrence nature. Screening for and treatment of CA-ASB are recommended to reduce this infection in catheterized patients which may develop secondary to mucosal bleeding during catheter placement [1]. Identifying patients at high risk for bacterimia would enable clinicians to target those patients for interventions such as giving antimicrobial agents, early catheter removal or surgery. Therefore, research directed at evaluating the uropathogens in men with BPO should lead to new and improved diagnosis, prevention, and treatment options.

It is with this background that this study was carried out to evaluate the uropathogens in men with BPO receiving care from Ekiti State University Teaching Hospital, Ado-Ekiti, South western Nigeria.

Materials and Methods


The study was a cross sectional study conducted at Ekiti State University Teaching Hospital, Ado-Ekiti, Nigeria. The study lasted a period of 12months;fromMarch 2016 to February 2017.

Inclusion criteria

All male patients with a diagnosis of BPO on catheter for more than 48 hours who were willing to participate in the study by signing the consent form were included in the study.

Exclusion criteria

All patients who were chronically bed ridden and those with obvious psychiatric illness, patients on antibiotic therapy and those who were symptomatic for UTI were excluded from the study.

Sample collection and processing

Clean-catch, catheter urine samples from the patients were obtained and processed within 2 hours of collection. Each well mixed specimen was inoculated using a standard wire loop into blood and MacConkey agar or using only Cysteine Lactose Electrolyte Deficient [CLED] agar and incubated aerobically at 37oc for 24hours.

Urine was examined macroscopically for colour and turbidity. Microscopic examination of centrifuged urine sediments was done by examination under x 40 objective for pus cells, red blood cells, casts, crystals and parasites. Urinalysis was done on all samples.

Culture was examined for significant growth after incubating for 24 hours. Bacteriuria of 103/μL and above was considered as significant growth. Colonies were characterized using a combination of colonial morphology, Gramm staining, standard biochemical and serological tests where appropriate.

Antibiotic sensitivity testing was performed using the modified Kirby Bauer disc Diffusion method. [9] Pure colonies of isolated organism were suspended in sterile normal saline inside bijou bottles and the turbidity of the suspension adjusted to 0.5 McFarland’s standard. A sterile cotton swab was dipped into the suspension and squeezed against the side of the bottle. The swab was then used to inoculate already dried Mueller Hinton agar before the application of single antibiotic discs and subsequently incubated at 37oc aerobically for 18-24hours.

Zone diameters of inhibition around each disc were measured using a calibrated ruler and interpreted according to National Committee for Clinical Laboratory Standard (NCCLS). Escherichia coli (ATCC 25922), Staphylococcus aureus (ATCC (25923) and Pseudomonas aeruginosa (ATCC 2785) were used as control for gram negative, gram positive and pseudomonas isolates respectively.

The antibiotics discs used included Ofloxacin (5μg), Augmentin (10μg), Levofloxacin (5μg), Cefuroxime (30μg), Ceftazidine (30μg), Ceftriaxone (30μg), Nitrofurantoin (300μg) Gentamycin (30μg), Erythromycin (5μg), Perfloxacin (5μg) and Ampicillin (10μg).

Ethical Approval

Ethical approval was given by Ekiti State University Teaching Hospital ethical committee.

The study was conducted in accordance with Helsinki Declaration, 1989 Revision. All participants had written informed consent before participation in the study.

Statistical analysis

Data was analyzed using Statistical package for Social Sciences version 20; qualitative variables were reported as percentages in frequency tables. Cases of CA-ASB, isolated organisms and their sensitivity patterns were reported in proportion of the total no of cases. Level of significance was set at p< 0.05.


A total of 78 patients were recruited into the study. The age range was 45-86 years. Mean age was 67.6±10.07. The prevalence of CAASB was 83.3%.

Figure 1 shows that BPO was commonest at 65 years and above.

Figure 1: Distribution of BPO according to Age category.

Table 1 shows that growth of pathogens was significantly higher in the age group 65 years and above.

Table 1:

Age category in years








Culture positive








No growth








Table 2 shows that the most prevalent clinical presentation of BPO was urinary retention followed by dysuria.

Table 2:



Mean age (SD)


Mean weight (SD)

59.4 (8.7)

Mean height (SD)

1.6 (0.08)

Currently married (%)


Not currently married (%)


No/primary education (%)


Secondary education (%)


Tertiary education (%)


Currently employed (%)


Not currently employed (%)


Haematuria (%)


Dysuria (%)


Frequency (%)


Hesitancy (%)


Urinary retention (%)


Past history of retention (%)


Past history of UTI (%)


Duration of catheterization (%)

1. <30 days


2. ≥30 days



Type of catheterization (%)

1. Urethral


2. Suprapubic



Where catheter was passed (%)

1. Private hospital


2. Emergency unit of teaching hospital


3. Outpatient clinic



Table 3 shows that the commonest urinalysis finding in BPO was haematuria followed by proteinuria. Commonest microscopic finding was pyuria and commonest pathogen was E.coli.

Table 3:


Frequency (%)























Culture positive


Isolated Organism (N=65)







Proteus mirabilis*


Pseudomonas aerugenosa*


Sensitivity Pattern (N=65)

























*2 samples had more than one organism; **Organism resistant to all tested drugs.

Besides, nitrofurantoin was the most sensitive drug in BPO and the quinones have the highest resistant pattern.


Benign Prostatic Hyperplasia (BPH) has been reported as the most common cause of urinary retention in older men [10]. The mean age of men with urinary retention secondary to BPH in this study was 67.6%±10.07 years. This is similar to the report of Yenli and colleagues who also reported the mean age of 62.8±16.8 years among Ghanaian men with urinary obstruction secondary to BPH [11]. The prevalence of 83.3% was recorded in this study. This is a very high prevalence compared to 33% recorded by Oshodi and colleagues in their study of UTI among patients with BPH [12]. This is in agreement with the fact that indwelling catheter is associated with increased frequency of CA-ASB [1].

The tendency to develop CA-ASB increases with advance age. In our study, we discovered that older men developed CA-ASB with men aged 65 years and above having significantly higher bacteria colonization than younger men (P=0.002). This finding may be due to the fact that increasing age is associated with decreased resistance to bacterial colonization, altered bladder emptying, poor perianal hygiene and urinary incontinence capable of enhancing the likelihood of developing infection/contamination [10].

The commonest presentation was complete cessation of urine (70.5%). This is majorly due to the fact that men in this country do not usually seek medical care until their medical condition has deteriorated. Thirty-four (43.6%) patients presented at the emergency department for the first time. This may be attributable to many factors visa-viz out-of-pocket payment for medical services, hospital protocols leading to prolonged waiting during consultations, ignorance and believe in traditional or alternative therapies. All these usually lead to delay in seeking early medical intervention. There is the need to urgently address the issue of medical insurance in this country as it is done in developed world.

In this study, about half of the patients (47.4%) presented to the private hospitals not necessarily because of cheaper services but due to prompt attention they get during the acute emergency of urinary obstruction. At times proximity of their residential place to the private hospitals may be responsible for the higher number of patients there rather than the tertiary care centre. Nonetheless, there was no significant difference in the development of CA-ASB (P=0.611).

The prevalence of infection was significantly higher in patients on urethral catheters than those on suprapubic catheters. (P=0.011) This is in agreement with Saint and colleagues study [8] that the use of suprapubic catheters is associated with a lower risk of UTI than the use of urethral catheters.

However, shorter duration of catheterization [<30 days] appear not to influence the outcome of CA-ASB in this study. There was no clear reason for this finding. Further studies into these trends are necessary.

Furthermore, evaluation of the urinalysis in our study indicated that the most prevalent abnormality was micro-haematuria (61.5%). This may be due to recurrent mucosal bleeding as a result of catheter placement at the initial management of the urinary obstruction or subsequent catheter replacement. This is similar to the argument of Hooton and colleagues [1] that it is necessary to screen for and treat CA-ASB in order to reduce this infection in catheterized patients which may develop secondary to mucosal bleeding during catheter placement [1]. There was also high prevalence of proteinuria (37.7%) which may be a pointer to a degree of disturbances in both the glomerular filtration and tubular reabsorption of proteins. This is indicative of a slight glomerular dysfunction and a permanent defect in the proximal tubule to reabsorb proteins probably due to a delay in the management of the obstruction [13]. This is even worse in our environment where 51.3% had previous history of urinary retention. It is important to educate people in this country on the need for early referral to a specialist when any lower urinary tract symptom is noted.

Moreover, the commonest uropathogens in this study were E.coli, Klebsiella, Proteus, and Pseudomonas species with a prevalence of 47.7%, 15.4% and 7.7% respectively. This is not too different from the finding of Oshodi and colleagues who reported a high prevalence with Proteus spp, Pseudomononasspp and E.coli in northern Nigeria [12]. But while E.coli was the commonest in our study, Oshodi and colleagues found the commonest organism to be Proteus spp. No reason could be immediately adduced for this difference but may be related to slight socio-cultural differences between the people from the western part of Nigeria and those from the northern part [14].

The isolated uropathogens were mostly sensitive to nitrofurantoin, followed by cefuroxime and ceftazidine. High resistance to perfloxacin, ampicillin, levofloxacin, and erythromycin in this study is similar to the finding of Oshodi and colleagues [12]. This implies that the resistant strains may have undergone directional selection where a single phenotype is favored, causing the trait frequency to continuously shift in one direction. The favored trait will then increase in frequency independent of its relative dominance over others [12].

The increased resistance to fluroquinones is in agreement with Zhang et al, Osterlund et al and Goettsch et al [15-18]. This is in support of our earlier reasons. However, a recent meeting organized by the National Institute of Allergy and Infectious Diseases (NIAID) in the USA seemed to promote the use of fluoroquinolones as the first empirical treatment for all complicated UTIs, including CAUTIs [19,20]. Whilst this policy might be practical, it may be difficult to extrapolate this to our community because of the high tendencies to abuse drugs.

The prevalence of multi-resistance (10.8%) recorded in this study requires further evaluation beyond the scope of this study.


There is high prevalence of CA-ASB in Nigeria and the commonest uropathogen is E.coli. Nitrofurantoin is the most common sensitive antibiotic but there are high multi-resistant strains. Quinones and penicillin are not first line medications in the management of CAUTIs in this country.


This study has some limitations. The fact that only eleven discs were tested has ruled out other antibiotic discs that may show sensitivity. Besides, only 78 urine samples were tested which is rather too few to be generalized to the entire population. Also, being a hospital based study; a community based research may yield better results.

Since no urine sample was collected prior to catheter placements, some of the patients may have harbored infection that was only manifesting after catheter has been passed. Thus giving rise to a false CA-ASB.


Authors appreciate the efforts of Dr. K.A. Adekeye for the statistical work of this manuscript. We also appreciate all the resident doctors, Mrs. R.O Olofinbiyi and Mrs. F. Davies of the department of Nursing Services, Ekiti State University, Ado-Ekiti, Nigeria for their enormous contributions to this work.


  1. Hooton TM, Bradley SF, Cardenas DD, Colgan R, Geerlings SE, Rice JC, et al. Diagnosis, Prevention, and Treatment of Catheter-Associated Urinary Tract Infection in Adults: 2009 International Clinical Practice Guidelines from the Infectious Diseases Society of America. Clinical Infectious Diseases. 2010; 50: 625-663.
  2. Nicolle LE, Strausbaugh LJ, Garibaldi RA. Infections and antibiotic resistance in nursing homes. Clinical Microbiology Reviews. 1996; 9: 1-17.
  3. Rogers MA, Blumberg N, Heal JM, Kuhn L, Greene MT, Shuman E, et al. Role of transfusion in the development of urinary tract-related bloodstream infection. Arch Intern Med. 2011; 171: 1587-1589.
  4. Tambyah PA, Maki DG. Catheter-associated urinary tract infection is rarely symptomatic: a prospective study of 1,497 catheterized patients. Arch Intern Med. 2000; 160: 678-682.
  5. Nicolle LE. Urinary tract infections in the elderly. Clin Geriatr Med. 2009; 25: 423-436.
  6. Nicolle LE . Catheter associated urinary tract infections. Antimicrob Resist Infect Control. 2014; 3: 23.
  7. Hollingsworth JM, Rogers MA, Krein SL, Hickner A, Kuhn L, Cheng A, et al. Determining the noninfectious complications of indwelling urethral catheters: a systematic review and meta-analysis. J Am Geriatr Soc. 2013; 159: 401-410.
  8. Saint S, Lipsky BA, Baker PD, McDonald LL, Ossenkop K. Urinary catheters: what type do men and their nurses prefer? Journal of the American Geriatrics Society. 1999; 47: 1453-1457.
  9. Bauer AW, Kirby WM, Sherris JC, Turck M. Antibiotic susceptibility testing by a standardized single disk method. Am J Clin Pathol. 1966; 45: 493-496.
  10. Rowe TA , Juthani-Mehta M . Urinary tract infection in older adults. Aging Health. 2013; 9: 519-533.
  11. Yenli EMT, Aboah K, Gyasi-Sarpong CK, Azorliade R, Arhin AA. Acute and chronic urine retention among adults at the urology section of the Accident and Emergency Unit of Komfo Anokye Teaching Hospital, Kumasi, Ghana. African Journal of Urology. 2015; 21: 129-136.
  12. Oshodi AJ, Nwabuisi C, Popoola AA, Edungbola LD, Agbede OO, Akanbi II AA, et al. Bacterial Uropathogen among Benign Prostatic Hyperplasia Patients at a Tertiary Hospital in Nigeria. Open Journal of Medical Microbiology. 2015; 5: 22-27.
  13. Al-Hazmi H. Role of duration of catheterization and length of hospital stay on the rate of catheter-related hospital-acquired urinary tract infections. Res Rep Urol. 2015; 7: 41-47.
  14. Mustonen S, Ala-Houhala IO, Tammela TL. Characteristics of protein excretion in patients with acute urinary retention. BJU Int. 2001; 87: 187-191.
  15. Ripples foundation supporting African women.
  16. Zhang YL, Geng SN, Lai FC, Wang NP. Survey on drug resistance to ciprofloxacin in common pathogenic bacteria. Di Yi Jun Yi Da Xue Xue Bao. 2002; 22: 378-379.
  17. Osterlund A, Olsson-Liljequist B. Fluoroquinolone resistance of human pathogenic bacteria. Resistant E. coli now appearing in Sweden. Lakartidningen. 1999; 96: 1965-1966.
  18. Goettsch W, Van Pelt W, Nagelkerke N, Hendrix MG, Buiting AG, Petit PL, et al. Increasing resistance to fluoroquinolones in Escherichia coli from urinary tract infections in the Netherlands. J Antimicrob Chemother. 2000; 46: 223-228.
  19. Schaeffer AJ. The expanding role of fluoroquinolones. Am J Med. 2002; 113: 45S-54S.
  20. Nicolle LE. Urinary tract infection: traditional pharmacologic therapies. Am J Med. 2002; 113: 35S-44S.

Citation: Adegun PT, Olaogun JG and Odimayo MS. Evaluation of Uropathogens in Bladder Outlet Obstruction Secondary to Benign Prostatic Hyperplasia. SM J Urol. 2017; 3(3): 1033.

Download PDF