Epidemiology and Pathophysiological Determinants of Staphylococcal Urinary Tract Infections in Enugu State

Abstract

In a study to investigate the epidemiology and pathophysiological determinants of staphylococcal urinary tract infection (UTI) in Enugu state, a total of 818 participants (290 males and 528 females) randomly selected, submitted freshly voided urine samples for laboratory investigation between 2013-2015. Candidates aged between 3-87 years comprised of apparently healthy individual (558) were selected from schools and various occupational groups and classes, while 119 pregnant women and 141 candidates with various medical conditions seen in the two tertiary hospitals serving the area of study were included. Samples were processed using standard microbiological techniques and confirmed with API identification systems (Biomerieux France). The major staphylococcal isolates were investigated for any pathological effects using albino Wistar rats. Results showed that 307 urine samples (37.5%) yielded significant bacterial growth of which 89 (10.9%) yielded staphylococcal species with Staph aureus 40 (44.9%) ranking highest, followed by S. xylosus 25 (28.1%), S. lentus 9 (10.1%), with S. capre, S. sciuri, S. heamolyticus and S. epidermidis yielding 3 (3.4%) each while S. hominis, S. capitis and S. saprophyticus ranked least with 1(1.1%) isolate each which difference was statistically significant (P < 0.05). Sex-wise distribution showed a female preponderance 69 (77.5%) as against their male counter parts 20 (22.5%) which difference was also statistically significant (P < 0.05) using fishers exact test for contingency. Age-wise distribution showed no statistically significant difference in the distribution of positive cases (P > 0.05) though the age group 22-32 years recorded the highest with 37 (41.6%) positives. These also apply to each of the different staphylococcal species except S. heamolyticus for which all 3 isolates were from males. According to occupational grouping of the study population, traders ranked highest in prevalence for staphylococcal spp UTI 18.7% followed by house wives 15.6%, tertiary students 11.5%, secondary students 9.2%, pupils 8.0%, civil servants 6.7%, with artisans 5.4% being the least which difference was statistically significant (P < 0.05). Of the 558 apparently healthy candidates, 60 (10.8%) were positive for staph spp UTI, pregnant women 24 (20.2%) of the 119 candidates while for candidate with different medical conditions (141), only 5 (3.5%) yielded staphylococcal organisms. Age and sex distribution for the positive staphylococcal UTI cases among the apparently healthy individuals showed a higher female positive group (40) as against their male counter parts (20) which was statistically significant (P-< 0.05), with the age group 22-32 recording the highest. For the 24 positive pregnant women, the age group 22-32 recorded the highest positive cases for staphylococcal UTI with 19 (79.2%) followed by the age group 33-43 with 4 (16.7%) while the age group 11-21 recorded only 1 (4.7%), which difference was also statistically significant (P < 0.05). Of the 141 cases sampled with different medical conditions, only 5 (3.5%) were positive for staphylococcal UTI (3.S. aureus and 2. S. sciuri) while for the apparently healthy and pregnant groups, S.aureus S. xylosus and S. lentus ranked highest. Antibiogram results showed a range of sensitivity (47.5 -72.5%) for S. aureus, (44 -72%) for S. xylosus, (44.4 -77.8%) for S. lentus while S. saprophyticus was generally resistant apart from levoflaxacin. Pathological studies using the 3 commonest Staph species revealed varying degree of toxicity effects for the kidney, liver and bladder with S. aureus showing a higher degree of toxicity especially with the kidney and effects were more significant than when compared with S. xylosus and S. lentus with effects generally increasing with increased dosing.