Discussion (Table 5) were more resistant to most of

 

 

Discussion

Enterobacteriaceae
family is the most   reported cause of
UTI and are usually resistant to many antibiotics resulting in recurrent UTIs,
particularly in the high risk population 16, 20.  They present a
public health challenge and thus deserve an adequate attention. For an in-depth
understanding of the underlying resistance genotypes and/mechanisms this study
characterized the enterobacterial
uropathogens with respect to drug resistance and their
?-lactamases production capacities. Antibiotic resistance is a key clinical and public health
problem in treating infections caused by enterobacterial uropathogens. Emergence
of beta-lactamases producing Enterobacteriaceae reduces therapeutic options
because the isolates often co-express resistance to other classes of
antibiotics. Our
predominant isolates (E. coli, Salmonella spp. and 
K. pneumoniae) showed variable resistance to most drugs tested  . This is similar to the findings of Ekwealor
et al. 1.
The fluoroquinolones and gentamicin were highly active against E.coli isolates and thus can be
prescribed for the emperic treatment of UTI caused by E coli. Similarly, in Libya Abubaker et al., 5
reported a very good susceptibility of uropathogenic E.coli to ciprofloxacin and a very low
resistance to gentamicin was equally reported by Elsayed et al 4 in Egypt. 

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In
the case of Salmonella spp, cefpodoxime
showed the highest activity against  Salmonella spp and unlike the E.coli isolates,  the salmonella spp. were resistant to the
flouroquonolones. Susceptibility test for K.
pneumoniae showed that amoxicilin,
cefpodoxine, cefotaxime,
aztreonam  and cefoxitin exhibited  very
poor anti-pneumococcal  activity while
the flouroquinolones showed very good 
activity which is in agreement 
with the reports of Sikarwar &
Batra 21 that a flouroquinolone, ciprofloxacin had a 90 %
antibacterial activity against uropathogens. It was observed that K.pneumoniae isolates (Table 5) were more resistant to most of the antimicrobial
agents tested than E. coli and
Salmonella  isolates . A
similar scenario of multidrug resistance (MDR) of uropathogenic Klebsiella spp. has been reported in
Libya 5. It should be noted that all the
isolates had poor susceptibility to co-trimoxazole and amoxicillin. This is in
agreement with recently published work in Ethiopia where high level of resistance (>70%) were recorded for
trimethoprim/sulfamethoxazole and ampicillin by uropathogens 22. The observed low susceptibility might not be
unconnected with the misuse of the agents as
trimethoprim-sulfamethoxazole and ampicillin were the first choice of drug for the empirical treatment of UTI 22. Several researches   have reported increasing prevalence of trimethoprim-sulfamethoxazole resistant-uropathogenic
strains and suggested fluoroquinolones as an alternative treatment choice for UTI
23. E.coli and Salmonella were very sensitive to aztreonam
and ceftazidime. This observed low resistance rates ( to aztreonam
and ceftazidime) may be due to less use of these drugs in treating bacterial
infections in Nigeria. A significant sensitivity to gentamicin was noted of E.coli and C. freundii (Table 6). Two
related studies in Abakilikii  and Enugu both in south-eastern Nigeria
equally reported a remarkable susceptibility of uropthogesns to gentamicin 18, 24.  This might be because gentamicin being a
parenteral preparation might be used with much restriction.  Improper antibiotic use: dose and duration of
administration have been reported as predisposing factors for the emergence of
antibiotic resistant strains in a locality 4.

Sixteen
(27.6 %) of the screen positive E.coli
was phenotypically confirmed to be ESBL producers. Similar rates (27.7%) of
ESBLs have been reported from a neighboring southeastern state, Enugu by
Ejikeugwu et al 18 and 26.1% in
south-western Nigeria 25. Lower prevalence
of ESBLs (6.7%) was detected phenotypically among uropathogenic  E. coli
in Northwestern Libya 5 . However, higher
prevalence of ESBL – producing uropathogenic E.coli (38.9%) was reported in Nepal 11 and 40 % in 
Potohar region of Pakistan by Ali et al.23.  The rates of resistance of ESBL – producing
bacteria to antibiotics have previously been reported to be geographically
dependent. This is due to the differences in antimicrobial usages and infection
control practices used in these locations 26

On
molecular level, the prevalence of ESBL producing was:  E.coli (60.34%), C. freundii (100%), K.pneumoniae
(64.28%) and Salmonella spp. (46.66%). These high rates are of serious
concern as the transmission of these enzymes is usually driven by insertion sequences, transposons, integrons,
and plasmids which facilitate the spread of these genes among other species of
bacteria 27. In addition, they often carry
genes that confer high levels of resistance to many other antibiotics and cause
high therapeutic failure among infected patients 16,
28. The increasing prevalence of infections caused by
antibiotic-resistant bacteria makes the empirical treatment of UTI difficult
and the outcome unpredictable and is thus associated with higher cost of
therapy, increased risk of complications, morbidity and mortality 4,16.  Many
studies reported that urine is an important source of ESBLs-producing E. coli 5,
29. A similar observation was noted by Iroha et al., 30 in a neighboring
Enugu state where 81.8% of ESBL producing
strains of E.coli was isolated from
urine of Outpatients in a tertiary hospital. 
ESBLs have been reported among 51–90% of Enterobacteriaceae in Asia.
Similar to our findings, Padmavathy et al., 31 reported that the   percentage of ESBL-producing E. coli was 66.9 %  in Chennai, India.