Extended spectrum beta-lactamase urinary tract infections.

Urinary tract infections (UTIs) are the second most commonly diagnosed infectious illness worldwide, with about 150 million diagnosed yearly.[1] Gram-negative bacilli are the most common pathogens that cause UTIs in both men and women with a ratio of 1:2, with Escherichia coli (E. coli) being the most prevalent type accounting for 75-90% of UTIs.[234] Usually these infections are treated with a variety of antibiotics, including β-lactams, β-lactam/β-lactamase inhibitory, flouroquinolones, and carbapenems.[24] However, in recent times these pathogens have increasingly become resistant to most of these antibiotics.[24]

Extended spectrum β-lactamase (ESBL) is an enzyme produced by Gram-negative bacilli responsible for the increasing resistances worldwide.[3] The enzyme is responsible for resistance of amino and ureido penicillin, oxyimino cephalosporin, and monobactams, but not to 7-α-substituted β-lactam.[56] Certain patients have been found to be more susceptible to these infections such as patients with numerous comorbidities, diabetes, live in nursing homes, frequent use of antibiotics, recurrent UTIs, older aged, and male sex.[35] Further risk factors are patients that have had intravenous treatments or urinary abnormalities.[5]

The increasing resistance to the more commonly used antibiotics has made empirical treatment more difficult. UTIs complicated by ESBL organisms tend to lead to uncertain outcomes and prolong hospitalisation, especially that these organisms tend to be multi-drug resistant.[5] Although previously these infections were only limited to hospitals, they have found their way into the community.[457] In an antibiotic susceptibility study, Hoban et al., found these resistant organisms are more susceptible to the carbapenems, imipenem and ertapenem, more than other antibiotics.[2] While Akram et al., found that ESBL infections were more susceptible to imipenem and amikacin.[1] Taneja et al., found that imipenem was the most effective, in addition to piperacillin-tazobactam and ceftrazidime-clavulanic acid.[7] They analysed over 9000 urine samples collected and examined, with about 2000 samples positive for uropathogens.[7] Of which 22.1% had multi-drug resistance and 36.5% were ESBL producers.[7]

There also seems to be a discrepancy between geographical regional resistances and susceptibilities of ESBL organisms.[12] Nonetheless, the EAU guidelines recommend the use of aminoglycoside or carbapenems as first line therapy until drug sensitivities have been established.[8] Hence why each region need to conduct a thorough study to evaluate which strain of ESBL is predominant and which antibiotic that strains is most susceptible to. This ensures a reduction in infected complicated cases. Furthermore, a look into the causality of resistance should be carried out to prevent further increasing resistances. In the meanwhile, regarding complicated UTIs in patients admitted with a high suspicion of an ESBL infection need to be treated with vigilance with empirical antibiotics with either aminoglycoside or carbapenems with urgent cultures and sensitivities sent for analysis. Once the results of the sensitivities are available, then appropriate antibiotic sensitivity to the organism can be administered. Furthermore, clinicians need to bear in mind the risk factors associated with ESBL UTIs to pre-empt a complicated infection.