The antibiotic profile of bacteria isolated from cases of urinary tract infections in Ile- Ife and the characterisation of the predominant escherichia coli
The primary objective of this study was to determine the antibiotic resistance profile of the various uropathogenic isolates from both in-patient and out-patient cases, and to investigate the virulence factors exhibited by the predominant E. coli isolates in order to determine their level of pathogenicity. Clean voided midstream urine samples were collected daily from patients at the Obafemi Awolowo University Teaching Hospital Complex (OAUTHC), and the Seventh Day Adventist Hospital (SDAH), Ile-Ife, between May 2002 and December 2004. Urine samples were obtained from 215 in-patients and 181 outpatients. There were 168 male (42.42%) and 228 female (57.58%) patients. The samples were cultured on McConkey Agar (Oxoid) or Cysteine Lactose Erythrocyte Deficient (CLED) medium for isolation of the organism with bacterial counts of 105 colony forming unit per milliliter (CFU/ml.) and above were considered as being indicative of urinary tract infection (UTI). Bacterial isolates were identified based on cultural, morphological and biochemical characteristics. Their antibiotic susceptibility pattern was determined by the agar disc diffusion method, using standard antibiotic discs. Production of virulence factors such as haemaglutinatinin, haemolysin, colicin and capsule by the E. coli isolates were also determined using standard methods. . The samples yielded a total of 412 isolates, made up of 33.25% E. coli, 19.42% Klebsiella pneumoniae, 9.47% Staphylococcus aureus, 8.50% Pseudomonas aeruginosa and, Proteus species (7.04%). Other organisms occurred to less than 5% of the total and these are: Serratia marcescens (4.13%), Coagulase negative staphylococci (3.88%), Providencia species (3.15%), unspeciated cocci (3.64%), Enterobacter aerogenes (2.66%), Salmonella species (1.46%), Pantoa aglomerans (1.21%), Morganella morganii (0.98%) and Citrobacter species (1.21%). The major organisms were more than 50% resistant to amoxicillin, trimethoprim/sulphamethaxole. gentamycin, nalidixic acid, augmentin tetracycline and erythromycin. The result also highlighted a high level of resistance to the fluoroquinolones; norfloxacin, (76.3% and 86.9%), ciprofloxacin (50.0%, and 65.7) and ofloxacin (42.5% and 51.1%) by the predominant E. coli and Klebsiella pneumoniae respectively. There was not much difference in the antibiotic resistance patterns of inpatient and outpatient isolates. Gram-positive isolates generally demonstrated lower antibiotic resistance than the Gram-negative ones. Nitrofurantoin was highly effective against all the Gram-negative isolates except Pseudomonas aeruginosa. Twenty-one (63.64%) of the 33 trimethoprim resistant E. coli were able to transfer their resistance traits into plasmidless E. coli K12 C600. Furthermore, the results revealed for the first time in this environment, that most of these multiple and highly antibiotic resistant E. coli isolates possess virulence factors such as haemolysin (7.3%), mannose resistant haemagglutinin (13.87%), colicin (9.49%) and capsule (37.23%), thus confirming that they are truly uropathogenic E. coli (UPEC) strains. In conclusion, this study shows that the resistance of isolates from both the inpatient and outpatient cases of UTI is high and widespread in this environment.