Urinary tract infections (UTIs) are the result of the intrusion of the urinary tract by microbial agents. They are rated as some of the most common infections in the world. Bacteria are mostly responsible for most of the UTIs worldwide [1] . Urinary tract infections affect both male and female patients of all age groups [2] . The migration of microbes from the bowel flora to the urethra is the most common route of infection in females [3] . Microscopy, culture and urine chemistry are the most common laboratory diagnostic tools used to detect causative agents of UTIs and their antibiotic sensitivity patterns. Due to emerging resistance, antibiotic sensitivity patterns have become important in informing appropriate treatment [2] .

Urinary tract infections mostly occur in women than in men due to their anatomical differences. A shorter and wider urethra in women than in men makes it easier for bacteria to make their way to the urinary tract [4] . Women also have more moisture around their urethra than men, causing microbes to be trapped [5] . Wiping from back to front enhances the spread of organisms to the urinary tract. The common symptoms of UTIs include: dysuria, pyuria, nocturia, increased frequency of micturition, urgency to urinate, cloudy or dark urine or hematuria, lower abdominal pain and back discomforts, nausea and spewing, loss of appetite, fever, fatigue and foul smelling urine [4] [6] .

The risk factors associated with acquiring UTIs include: diabetes, immune suppression, hypertension, allergies, increased sexual activity, catheterization, use of diaphragms, birth control pills and spermicidal agents, age and gender, delays in micturition and abuse of antibiotics [5] [7] -[9] . In most developing countries, especially in Africa, malnutrition, poor hygiene and low economic status are part of the risk factors of UTIs [3] [8] . The ABO blood group has also been regarded as a risk factor for UTIs [5] .

There are a number of drugs universally used against microbes causing UTIs such as tobramycin, kanamycin, gentamycin, ciprofloxacin, amikacin, and cotrimoxazole where some resistance has been detected [7] [8] [10] . Studies have shown the resistance of E. coli to a variety of drugs such as sulfamethoxazole, ampicillin, cephalothin, ciproflaxin, amoxilin, augmentin, gentamycin and other medications [3] [8] [10] .

Gram negative organisms are mostly isolated particularly E. coli and K. pneumoniae. The common gram positive isolates are S. aurues and S. epidermidis [5] [9] -[11] . Past studies have shown that the common etiological agents of urinary tract infections include E. coli causing up to 80% of the infections [8] [10] . According to most international studies; E. coli, Klebsiella sp., Enterococcus sp., Proteus sp., Pseudomonas aeruginosa and Candida sp. are the most commonly isolated organisms [5] [9] -[12] .

In Africa, women are the frequent victims of UTIs and E. coli is also said to be the most common agent isolated [4] [13] . However, a study done in Benin in Midwestern Nigeria proved otherwise. In this study, males were more affected by UTIs than females and Alcaligenes species were the most common isolates from patients, followed by K. aerogenes, then E. coli [3] . In another study, Klebsiella species were the leading uropathogens in both sexes of out-patients, followed by E. coli, S. aureus and then C. albicans [14] . A study done in Benin City in Nigeria showed that S. aureus was the most common organism isolated from both genders [15] . Emergence of antibiotic resistance in UTI causing organisms is a serious public health problem particularly in the developing world [3] [12] .

The study was aimed at determining the common etiological agents of urinary tract infections, their antibiotic sensitivity patterns, and the most affected gender by the UTIs in patients referred to Namibia Institute of Pathology (NIP) in Windhoek throughout 2012.

The study determined the common etiological agents of UTIs among patients whose urine samples were submitted to NIP. As expected E. coli (18.9%) was frequently encountered. However, the comparatively low percentage of E. coli in this study does not compare to those reported by other studies. Other studies had a higher percentage of E. coli. In some European studies for instance the percentage of E. coli ranged from 35% to 67% [5] [7] [9] [16] , while in some African studies the percentage of E. coli ranged from 32% to 49% [2] [13] [14] .The difference in E. coli percentage could be due to different population sizes and the number of microbes isolated; this study’s population size was 20,438 from which 119 isolates were obtained. Other studies had a much smaller population size and the number of isolates where also not so many [3] [4] [15] [17] .

E. coli’s prevalence was consistent with some studies around the world [2] [8] [9] [11] [13] . However, in Africa there were changes in the prevalence of microbes responsible for UTIs with Klebsiella species, Alcaligens species and Staphylococcus species being the common isolates [3] [14] [15] [18] . This could be due to the presence of different organisms in communities from different geographical regions which can potential infect the different populations.

Other frequently isolated organisms in this study were P. mirabilis, E. faecalis, K. pneumoniae, S. epidermidis, Yeast but not C. albicans, ESBL’s E. coli, C. albicans, S. odorifera, K. oxytoca and Enterococcus species. However, all this isolates were mostly isolated from females than in males. The commonly isolated organisms from males were: ESBL’s K. pneumoniae, P. aeruginosa and S. haemolyticus. These findings were also isolatedby other researchers not necessarily in this particular order of frequency [9] [14] [19] . Several UTI studies have indicated that most of the time the most common organisms causing UTIs in women are not the same organisms frequently isolated in males [3] [13] -[15] .

Specimens received from females were more prone to UTIs than males in the current study. Apart from one study conducted in Nigeria where males were more affected by UTIs than females [3] , most studies have shown that women stand a higher chance of acquiring a urinary tract infection than man [6] [7] [9] [13] [15] . This is due to the anatomical difference in women and men. In women it is easier for microbes that are normal flora in the rectum, especially the gram negative bacteria, to migrate from the anus to the urethra [14] [20] . More moisture around the urethra in females traps the microbes enabling them to spread [3] . This also explains why Candida albicans and other yeast were frequently isolated from females than males. Fungi grow and spread well in moist areas. The most affected age group in this study was that of 20 - 29 in both males and females with 24.9%. These findings were common in most studies and this could be because the age group is the most sexually active; which is one of the common risk factors attributed to UTIs [2] [3] [8] .

Data on the antibiotic sensitivity patterns of the isolated organisms was also compiled and analyzed. The drugs to which the common organisms were resistant to were amoxicillin and cotrimoxazole; they were resistant to almost all the common isolates in this study. The high resistance of amoxicillin and cotrimoxazole in this study was similar to most studies in the world [7] [12] [17] [21] -[24] . In contrast to this, a study done in the United States of America showed that E. coli was sensitive to cotrimoxazole [25] . Other anti-microbial agents such as augmentin, amikacin, cefuroxime, ciprofloxacin, gentamycin, nalidixic acid, nitrofurantoin, were resisted by at least one common isolate, especially ESBL’s E. coli. These findings partially corresponded to somestudies, which indicated them as the most effective drugs and while others indicated that they were also resisted by ESBL’s E. coli [3] [4] [7] [10] [13] [17] [22] -[24] .

Ten cases of UTIs were caused by Schistosoma haematobium. In another study done in Ibadan Nigeria, four cases of UTIs that were caused by Schistosoma haematobium [2] .This study has indicated that the isolated bacteria are resistant to at least two antibiotics. This calls for physicians to rely on laboratory guidance before they prescribe therapy. This will minimize the chance of microorganisms developing resistant genes. There a rise in the frequency of isolation of organisms such as Serratia species and Staphylococcus haemolyticus, which according to literature are not found in large quantities in UTIs. The rise in ESBL’s E. coli and ESBL’s K. pneumoniae was also quite alarming [26] .

The limitations of the study were that only a single laboratory was used to collect the data as other laboratories in Windhoek would have also contributed valuable information concerning urinary tract infections. Some organisms isolated had only their genus name recorded but not the species name. Furthermore not all the microbes were tested against the available antibiotics and sometimes there were only less than 5 isolates that were tested against a specific antibiotic. Available data on comorbidities could have been included and analyzed to show any relationship between UTIs and other clinical factors.

The common etiology of UTIs in Windhoek was Escherichia coli and women were mostly affected than men. Most of the isolates were resistant to at least one antibiotic, although ESBL’s had resistance to more than ten antibiotics. The common causes of urinary tract infections in males were ESBL’s Klebsiella pneumoniae. The most ineffective drugs for this study were amoxicillin cefapime, ofloxiccin and piptaz and cotrimoxazole.

The authors would like to thank the Namibia Institute of Pathology for providing access to the data used in the study.

Niitembu JanyengaVeronika Jatileni,InnocentMaposa,Rooyen TinagoMavenyengwa, (2015) A Retrospective Study of the Variability in Etiological Agents of Urinary Tract Infections among Patients in Windhoek-Namibia. Open Journal of Medical Microbiology,05,184-192. doi: 10.4236/ojmm.2015.54023