High rates of multidrug resistance among uropathogenic Escherichia coli in children and analyses of ESBL producers from Nepal

Urinary tract infection (UTI) is among the most common causes of febrile illness in children requiring antimicrobial treatment [1]. Worldwide, an estimated 8% of girls and 2% of boys experience at least one episode of UTI by the age of seven years and recurrence occurs in 12-30% of them within a year [2]. Pediatric UTI in many instances, remain under-diagnosed because of the absence of specific symptoms and signs, particularly in infants and young children [2, 3]. Therefore, accurate diagnosis and appropriate use of antimicrobials for treatment and prevention of urinary tract infections (UTIs) is vital to reduce the burden and also to prevent the possible long-term consequences [4].

Escherichia coli have been recognised as the most common pathogen accounting for majority of urinary tract infections in children [5]. Antimicrobial therapy, usually of traditional antibiotics, is commonly prescribed to treat urinary tract infections in pediatric patients. However, increased rates acquired resistance in E. coli has made usual antibiotics less acceptable choice for empirical therapy in recent years [1]. The most common mechanism associated with acquired resistance in E. coli and other Enterobacteriaceae is the production of hydrolytic enzymes called β-lactamases [6, 7]. Extended-spectrum β-lactamase (ESBL), a major beta lactamase enzyme, has the ability to hydrolyze oxyimino-cephalosporins, and monobactams but not cephamycins or carbapenems and inhibited in-vitro by inhibitors such as clavulanic acid, sulbactam and tazobactam [8]. Since their evolution in 1983, more than 300 types of ESBLs have been identified in various members of the family Enterobacteriaceae and other non-enteric organisms [3, 6]. The infections associated with these ESBL producing isolates are difficult to treat because of their resistance towards beta lactam agents and also due to the emergence of co-existing resistance determinants such as aminoglycosides and fluoroquinolones [7]. Moreover, emergence of ESBL producing bacteria, particularly E. coli and K. pneumoniae causing pediatric urinary tract infections is a worldwide concern [9]. Options for the treatment of such multidrug resistant (MDR) gram negative bacterial infections are generally limited, and very few antibiotics are approved for use in children [10].

In Nepal, pediatric UTIs are usually treated empirically because of the unavailability of standard therapeutic guidelines and local susceptibility data [11, 12]. Knowledge of the etiological agent of UTIs and their antimicrobial resistance patterns in our setting may help clinicians in choosing the appropriate antimicrobial treatment. Moreover, most of the studies on pediatric urinary tract infections caused by multidrug resistant and ESBL producing bacteria have been reported from western world [10, 13], but the same from South Asian region including Nepal are scarce on the published literature [14]. In this perspective, the present study was designed to investigate the clinical isolates of multi-drug resistant and ESBL producing Escherichia coli causing urinary tract infections in children visiting a tertiary care teaching hospital in Nepal.

To the best of our knowledge, this report represents the first description of ESBL producing uropathogenic E. coli involved in pediatric cases of urinary tract infections from our country, Nepal. Urinary tract infections are the most common infections in children and E. coli being leading pathogenic agent in these infections; it was our matter of interest. There was no previous report before this study to estimate the most common pathogen and its resistant pattern in pediatrics patients with urinary tract infection in our hospital.

The incidence of urinary tract infection based on significant bacterial growth among pediatric patients in this study was 19.6% and E. coli (68.5%) was the predominant pathogen. Similar rates have been previously reported from nearby hospitals [11, 12] and from studies of other countries [18–22]. Concurrently, significantly more females (61.0%) were found with UTI corroborating with other similar studies [12, 19, 20]. In our study, children of age group 1-4 years were found with highest number of UTI cases (contingency coefficient 0.104). Similar study from nearby hospital also reported that children less than six years of age were found UTI prone [11]. Urinary tract infection was significantly more prevalent in the female children of age group 1-4 and 5-9 years and also, more inpatients were found with UTI (p < 0.05). The higher rates of UTI in this age group might be due to immune status, sanitation, and ascending infection with fecal flora.

The high prevalence of ESBL-producing uropathogenic E. coli (38.9%) among children is reported in this study. In addition, this study also documents the enhanced resistance of ESBL producing E. coli to other antimicrobial groups like aminoglycosides and fluoroquinolones. Indeed, variations in the prevalence rates of ESBL-producing E. coli isolates in children around the globe and even among different hospitals within a country have been reported. Our prevalence rate of ESBL producing E coli (38.9%) is close to the findings reported by other studies in different parts of Asian region including Shettigar et al. (37.7%) from India [22], Pourakbari et al. (37%) and Rezai et al. (30.5%) from Iran [21, 23], Moore et al. (44%) from Cambodia [19] and Kizilca et al. (41.4%) from Turkey [24]. Extremely higher rates of ESBL E coli have also been reported, notably by Chinnasami et al. (83%) from India [25], Masud et al. (53.8%) from Bangladesh [20] and Shah et al. (50.9%) from Pakistan [18]. The increased rate of ESBL-producing bacteria causing infection in community as well as hospital settings constitutes an undeniable trend. Worldwide, pediatric UTIs due to ESBL-producing bacteria are an important part of this problem because they limit therapeutic choices and increases morbidity of infection [26]. However, lower rates of ESBL-producing E. coli were also reported, particularly from developed countries including 9.3% from USA [27], 10.2% from Korea [28], 14% from Taiwan [26], 14.1% from Lebanon [5] and 20.2% from Turkey [29]. These variations in the rate of ESBL producing strains of E coli among UTI cases might be attributable to the geographical difference, local antibiotic prescribing policy, the extensive use of broad spectrum antibiotics especially third generation cephalosporins and endemicity of drug resistance pathogens in the locality.

ESBL producing bacteria causing infections in children may have various complications and adverse outcomes [30]. ESBL producers are non susceptible to aminopenicillins and ureidopenicillins as well as extended-spectrum β-lactam agents like second- and third-generation cephalosporins. Use of these agents as the first choice for the treatment of urinary tract infections may lead to the inappropriate treatment and predispose to long term renal complications [24]. Therefore, antimicrobial therapy in infections with ESBL producing organism is really challenging. Published reports showed that ESBL- producing strains causing UTI in children associated with prior hospitalization, beta-lactam therapy, catheterization, underlying co-morbidity and infancy [24].

In this study, multidrug resistant (MDR) and extensively drug resistant E coli were found 64.9% and 5.0% respectively. Increasing pattern of resistance of urinary tract pathogens against common antibiotics in Nepal have also been reported by other researchers [12, 31] but MDR rates and drug resistance pattern among pediatric isolates from Nepal was not available. It is observed that ampicillin, cephalexin, ciprofloxacin and cefixime were poorly effective against uropathogenic E coli. Only 13% of the isolates were found susceptible to all the antibiotics tested. Cephalosporin, the commonly prescribed antibiotic as empirical therapy in pediatric and adults, resistance to this group of antibiotics was found high. Almost 45% of E coli isolates were resistant to at least one cephalosporin and monobactam. Similar rates of antimicrobial resistance was documented in the study from Bangladesh [20], Iran [32] and India [14]. However, compared to previous reports from Nepal, we observed a considerable increase in resistance against penicillins, aminoglycosides, quinolones and ceftriaxone [12, 31]. Lower rates of resistance among the pediatric isolates causing UTI have been documented in western countries [33].

Higher resistance to penicillins third generation cephalosporins in this study has been attributable to ESBL production among gram negative isolates. In ESBL producing isolates, augumentins (combined with beta lactamase inhibitor) such as amoxicillin clavulanate or piperacillin tazobactam can be used as alternative antimicrobials [34]. However, in this study, alarming state of resistance was observed among ESBL producers towards amoxicillin clavulanate (100%) and piperacillin tazobactam (27%). In the case when UTI is caused by an ESBL producing bacteria in children, the broadest-spectrum antibiotic agents such as carbapenems are recommended [35] but they are only useful in hospitalized patients. In this study, too, carbapenems were found effective to the ESBL isolates. Nevertheless, for pediatric UTIs in our setting, cotrimoxazole, amoxicillin clavulanate, ciprofloxacin and amikacin can still be used as first line therapy. Furthermore, other non carbapenem groups of antibiotics in UTIs due to ESBL-producing strains have also been described [36, 37]. ESBL stable cephamycins, fosfomycin and nitrofurantoin were shown effective for UTIs caused by ESBL-producing strains but their clinical utility as monotherapy is controversial [38–40]. In addition, ESBLs usually confer resistance to other classes of antibiotics, such as quinolones and trimethoprim/sulfamethoxazole, therefore susceptibility testing of these agents is important [23]. In this study, entire MDR isolates were resistant to ampicillin and 33% isolates were resistant to cotrimoxazole, 19% to piperacillin tazobactam and 8% to imipenem whereas no isolates were found to be resistant to colistin and tigecycline. Similarly, all XDR isolates were resistant to most of the antimicrobials tested whereas colistin and tigecycline were the most effective regimens against XDR isolates. Similar rate of resistance has been documented by Ansari et al. [41] but their study included E coli isolates from all age groups.

The level of drug resistance in uropathogenic E coli among pediatric patient in this study is a serious issue. Previous reports have suggested that higher resistance is likely to be occurring in the communities with higher proportion of young children and high antibiotic consumption [42]. In Nepal, higher antimicrobial pressure for community infections and inappropriate therapeutic guidelines for pediatric patients might be attributable to this menacing scenario [12, 31]. Resistance to the broad spectrum cephalosporins, fluoroquinolones and aminoglycosides among the ESBL producing E.coli isolates in this study necessitates the use of carbapenem as alternative choice for pediatric UTIs. Although we found carbapenems as the most effective agent against the ESBL but the high rate of resistance from similar studies is of special concern [41]. Furthermore, the genes associated with antibiotic resistance usually reside in plasmid and may transfer antibiotic resistance to other wild strains of bacteria [20]. Therefore, evidence based therapy with broad spectrum antibiotics for serious or critical cases to prevent bacterial resistance is extremely needful. Aminoglycosides, amoxicillin clavulanate and trimethoprim sulfamethoxazole/cotrimoxazole would be useful alternatives as empirical antibiotics for children suspected with UTIs in our scenario.

We found the menacing state of drug resistance in almost all of the E coli isolates included in this study. Childhood UTIs caused by ESBL-producing E. coli has been emerged as a serious problem in our setting. Aminoglycosides and carbapenems can be used as alternative regimens for serious infections caused by MDR E coli. Furthermore, it is extremely necessary to formulate a strict antibiotics prescription policy and prudent use antibiotics in our country.