A decade of trends in the distribution and antimicrobial susceptibility of prevalent uropathogens among pediatric patients from Tehran,Iran during 2005—2016

Ali Rez Nteghin ,Sin Krji ,Khosrow Zmni

a Ali Asghar Clinical Research Development Center (AACRDC),Ali Asghar Children’s Hospital,Iran University of Medical Sciences,Tehran,Iran

b General PractitionerAli Asghar Children’s Hospital,Iran University of Medical Sciences,Tehran,Iran

c Student Research Committee,Iran University of Medical Sciences,Tehran,Iran

d Department of Microbiology,School of Medicine,Iran University of Medical Sciences,Tehran,Iran

KEYWORDS Urinary tract infection;Antimicrobial resistance;Pediatric hospital

Abstract Objectives: To determine changes in the distribution of uropathogens and their antimicrobial resistance in pediatric patients in a children’s hospital from 2005 to 2016.Methods: A cross-sectional analysis of uropathogens and their antimicrobial resistance within inpatient children was performed over the 11-year period,2005 to 2016,in Ali Asghar children’s hospital.The rate of antibiotic resistance among patients was evaluated according to demographic data including age,sex,urinary tract abnormities and history of antibiotic consumption.Results: In total,958 female and 349 male positive cultures were analyzed. Escherichia coli(E.coli)(77.6%)was the most common causative agent of urinary tract infection (UTI) in children and Klebsiella pneumoniae (10.4%), Pseudomonas aeruginosa (2.4%),and Enterococcus spp (2.4%) were less frequent isolated bacteria.The resistance rates of E.coli isolates were increased against amikacin,ceftriaxone,ceftazidime,ciprofloxacin,cotrimoxazole and imipenem from 2005 to 2010.However,we observed a decreasing trend for some of antibiotics including amikacin,gentamicin,imipenem,ceftazidime and cotrimoxazole during 2014—2016.The rate of antibiotic resistance was greater in boys than in girls against many antibiotics.The rate of resistance to amikacin,gentamicin,nitrofurantoin and cotrimoxazole in patients aged ＜1 year was higher than other age groups(p＜0.001).A higher antibiotic resistance rate was observed in patients with anatomical abnormality and those who have had a history of antibiotic consumption.Conclusion: The study indicated the significant decrease in E.coli antibiotic resistance in the last 3 years.An effective empirical treatment regime should be based on local epidemiology and antimicrobial susceptibility testing.

1.Introduction

Urinary tract infections(UTIs)are the most common infection in the pediatric population,and a common cause of hospitalizationininfancy andchildhood[1,2].UTIs aresignificantly caused by Gram-negative bacteria such as

Escherichia coli

(

E.coli

)and

Klebsiella pneumoniae

(

K.pneumonia

e),but Grampositive pathogens (

e.g.,Staphylococcus saprophyticus

and

Enterococcus faecalis

) may also be involved [3—5].The disease severity and outcome of UTI can also differ significantly,and are related to various factors,including gender,age,the genetic and susceptibility of the host,type of causative organism,response to antibiotic therapy,the pattern of antibiotic resistance,and the clinical management of the patient[6,7].Whereas,UTI clinical manifestations in neonate and children are nonspecific presentations[8].For this reason,it should be done promptly urine analysis,culture and antimicrobial susceptibility testing on urine specimens that all of thesecanbeanaid inthediagnosisofUTI.Furthermore,there is increasing prevalence of multidrug-resistant(MDR)organisms in pediatric hospitals,with particular concern for emerging resistance to broad-spectrum cephalosporins and carbapenems [9,10].Although international guidelines provided empiric treatment recommendations,these empiric recommendations should be modified by specialists and microbiologists in any hospitals for bacterial infections [11].Since we found no comprehensive study on antimicrobial resistance in this setting.Awareness and understanding of local antimicrobial resistance patterns are important for antibiotic stewardship and initiating empiric antibiotic therapy.In this study,we evaluated the frequency of uropathogens and their susceptibility to tested antibiotics over a 10-year period as well as effective factors in the incidence of UTI and antimicrobial resistance in Ali Asghar children’s hospital.

2.Material and methods

2.1.Study design and setting

The study was performed at the Ali Asghar children’s hospital,Tehran,Iran,the pediatric center in the northern end of Tehran.The source of extracted data was the hospital records of the patients regarding age,sex,date,method of urine sample collection,urine culture results,presence of urinary tract anomalies,previous antibiotic consumption and antibiogram results.The latter routinely was based on the report of the laboratory unit of Ali Asghar children’s hospital which reports antibiogram by a semi-quantitative approach based on disk diffusion method,and the available laboratory guidelines.

2.2.Inclusion criteria

In the current study,we designed a study population using simple non-random sampling to recruit all cases with the diagnosis of UTI admitted to Ali Asghar children’s hospital,Tehran,Iran in 2005—2016 period.Furthermore,UTI was defined as:I)A bacterial growth ≥10CFU/mL in midstream urine culture,or ≥10CFU/mL from a urine sample obtained by catheterization;II) The presence of greater than five leukocytes per high-powered field and bacteriuria or a positive nitrite test or leukocyte esterase.Specimens of bagged urines were included only if there were two specimens collected with identical results.Only the result of the first positive urine culture was extracted.In the event of two separate initial positive cultures,the result of suprapubic aspirate was taken into account.

2.3.Exclusion criteria

Those with incomplete records,including the absence of two confirmatory progress notes regarding urine sample collection method were excluded from the study.Mixed growth urine cultures denoting the growth of two or more organisms in one sample were excluded,as they were likely to represent contaminated samples.Episodes with urine samples growing fungal organisms were also excluded.

2.4.Data analysis

All extracted data entered in SPSS Ver.22(Armnok,NY,USA)software spreadsheets.The frequency of uropathogens and their resistance to the tested antibiotics were compared for four time periods by using the Chi-square test.In addition,we analyzed the impact of age,gender,anatomical abnormalities and previous antibiotic administration on antibiotic resistance for a period of 10 years(2005—2016).

3.Results

A total of 1307 non-duplicate urinary isolates were recovered from 958 (73.3%) girls and 349 (27.7%) boys with UTI during the study period.The biggest percentage of isolates was from children who have ＜1 year of age (37.0%),while the number of isolates were variable among the remaining age groups (18.8% in patients aged 1—2 years,6.6% in patients 2—3 years,7.1% in patients 3—4 years,5.7% in patients 4—5 years,6.9% in patients 5—6 years and 17.9% in patients ＞6 years).The most frequently recovered isolates were

E.coli,

77.6%;

K.pneumoniae

,10.7%;

Enterococcus

spp,2.4%;and

Pseudomonas aeruginosa

,2.4% (Table 1).Furthermore,among isolates recovered from girls and boys,the distribution of microorganisms was consistent with the overall study population.Besides,the resistance rates against antimicrobial agents were summarized in Table 2 for Gram-negative and Gram-positive isolated bacteria respectively.In Gram-negative uropathogens,the rates of resistance to ampicillin,cotrimoxazole,and oral cephalosporins were very high,and to imipenem,cefepime and amikacin were lower than others.Vancomycin,nitrofurantoin and ciprofloxacin were more effective against Gram-positive bacteria.In addition,the rates of resistance to amikacin,gentamicin,nitrofurantoin and cotrimoxazole in patients aged ＜1 year were higher than other age groups(

p

＜0.001).However,no significant correlation was found between aged groups with resistance to other antibiotics.Table 3 illustrated resistance rates to tested antibiotics,according to gender during the study period.Also,the rates of resistance to many antibiotics were greater in boys than in girls.As shown in Table 4,the changing of resistance was significant for amikacin,ampicillin,ceftriaxone,ceftazidime,nitrofurantoin and gentamicin during the study period (2005—2016).Although resistance to ceftriaxone increased from 30.5% in 2008 to 44.7% in 2013,the resistance rates tended to decrease in 2016.In the next section,we focused on the effects of anatomical abnormalities on the distribution of pathogens and their antibiotic resistance represented in Tables 5 and 6.The frequency of uropathogens including

Enterobacter.

spp and

Pseudomonas aeruginosa

was higher in patients with anatomical abnormalities in compared to those without anatomical abnormalities.

Table 1 Frequency of uropathogens isolated from urine cultures.

We next examined the effects of previous antibiotic consumption on antimicrobial resistance.For this reason,patients with anatomical abnormalities such as the neurogenic bladder,perineal stenosis,double terminal urethra were excluded and only 338 patients were included in this section.More details were represented in Table 7.

Table 2 The pattern of antibiotic resistance for selected uropathogens.

Table 3 Distribution and frequency of antibiotic resistance uropathogens by gender.

Table 4 Antimicrobial resistance trends among Escherichia coli isolates from Ali Asghar Hospital,2005 to 2016.

Table 5 Distribution of UTI etiological agents in patients with and without anatomical abnormalities.

Table 6 Distribution of resistant isolates of Escherichia coli among patients with and without anatomical abnormalities.

Table 7 Association of previous antibiotic consumption and antibiotic resistance.

4.Discussion

Antimicrobial resistance (AMR) is a serious concern world wide and the rising of multidrug resistance strains among inpatient and outpatient is accounted as a potential risk.At the national level,each country should promote knowledge through surveillance and investigation in the field of AMR.Throughout the study period,

E.coli

remained the most prevalent causative agent of UTI in the pediatric population,and this finding is consistent with previous studies[2,12—14].Although

E.coli

is one of the members of the intestines microbiota,this organism can result in various infections,including meningitis,gastroenteritis,bacteremia and UTI.In the present study,the proportion of UTI was significantly higher in females (73%) than in males(27%).Our results were consistent with other studies that showed that UTI was more frequent in females[5,13,15,16].High frequency of UTI in females can be due to anatomical differences such as shortness of urethra and close space between the anus and urethral orifice [17,18].However,some studies reported that UTI at an early age(＜2 years) is greater in boys than that in girls [19,20].This difference can be due to the lack of circumcision in young boys.In addition,in our study,the age distribution for UTI was similar to that in other studies from Iran and other countries [2,15].Overall,we found resistance rates of

E.coli

to ampicillin,cefazolin,cotrimoxazole,cefuroxime,and cephalexin were increased during the study period.In contrast,resistance to ampicillin was 40.9%in

Enterococcus

isolates.Similarly,in Taheri and coworker’s study [21],the resistance rates of

E.coli

isolates to ampicillin,cefixime,ceftizoxime,cephalexin,ceftazidime and gentamycin were93.6%,85.7%,78.9%,77.3%,53.8% and 59.5%,respectively.Furthermore,high-frequency resistance to these antibiotics was reported among

E.coli

isolates in other studies[2,13,22].Our findings suggest that ampicillin and oral cephalosporins should be used as empiric agents only when potential benefits outweigh risks.According to the results of the present study the rates of resistance to amikacin,gentamycin and nitrofurantoin in patients aged ＜1 year were higher than other age groups,while resistance to cotrimoxazole was increasing in patients aged ＞1 year.Also,the prevalence of resistance between boys was higher than girls to antibiotics such as amikacin,gentamycin,ceftriaxone,ceftazidime and nitrofurantoin.However,the impact of gender and age in increasing antibiotic resistance is a controversial issue between researchers [23,24].In addition,there are several main risk factors including catheterization,use of broad-spectrum antibiotics,acquisition of multidrug-resistant strains,prolonged hospitalization,presence of underlying diseases and urinary system disorders that influence UTI incidence and antibiotic resistance.In the current study,due to insufficient data,we only evaluated changes of antimicrobial resistance

E.coli

isolates.During the study period,from 2005 to 2010 resistance to amikacin,ceftriaxone,ceftazidime,ciprofloxacin,cotrimoxazole,and imipenem in

E.coli

isolates increased.In a previous study from Spain,the rate of resistance to third-generation cephalosporins and fluoroquinolones increased significantly for

E.coli

infection [25].The increasing trends of the amikacin,ceftriaxone,ceftazidime,ciprofloxacin,cotrimoxazole,imipenem resistance rate for

E.coli

are consistent with other national antimicrobial resistance studies [26].However,we observed decreasing antimicrobial resistance of

E.coli

between 2011 and 2016.Furthermore,resistance to nitrofurantoin significantly decreased during the study period.From 2005 to 2010,relative increasing of resistance rates can be due to various factors such as overuse or inappropriate antibiotic therapy for hospital or communityacquired infections,antimicrobial prophylaxis,poor education for combat with antimicrobial resistance,selection of patients from referral hospital,and overuse of antibiotics for prevention and therapeutic aims in livestock and poultries.However,we found the decrease in resistance rates of

E.coli

in the last years of the study period.In this context,the management of antibiotic prescription by physicians,rising of understanding individuals for antibiotic usage and promotion of infection control policies were affected in decreasing antibiotic resistance.Previous studies indicated that various factors including the type of strains,expression of virulence factors,misuse or overuse of antibiotics in human and animal,anatomical abnormalities may influence the antimicrobial resistance rates[27—29].According to our results,there is an association between anatomical anomalies,distribution of uropathogens and antibiotic resistance.We found that frequency of

Enterobacter

spp and

Pseudomonas aeruginosa

was higher in patients with anatomical abnormities than those without anatomical abnormities.Furthermore,the study results revealed that in patients with anatomical anomalies in comparison to patients without anatomical abnormalities,the resistance rates to cefazoline,cephalexin,cefepime,ceftazidime,ceftriaxone,ciprofloxacin,gentamycin and nitrofurantoin increased (

p

＜0.05) while the rising rates of resistance was not significant for amikacin,ampicillin,imipenem or cotrimoxazole.Ahmed and coworkers [30]reported that the resistance rates to ampicillin and trimethoprim/sulfamethoxazole among patients with the genitourinary abnormality were more than those without such abnormalities.In another study conducted in Ontario,Ottawa,Allen et al.[31]reported that among patients with genitourinary tract abnormalities,the frequency of resistant

E.coli

isolates were almost four times more than those without such abnormalities.The result of this study shows that the previous history of antibiotic consumption appeared to be significantly influenced by

E.coli

resistance to amikacin,cefepime,ceftazidime,ceftriaxone,nalidixic acid and cotrimoxazole.In the management of patients with recurrent infections,vesicoureteral reflux,or other urological abnormalities,antibiotic prophylaxis is a central strategy for the prevention of UTI in children.In this context,Lutter and coworkers [32] reported that the resistance rates in

E.coli

,

Pseudomonas aeruginosa

and

Klebsiella oxytoca

isolates were increased to cefotaxime among children receiving prophylactic antibiotics.Also,Olesen et al.[27] reported that there is high association between the use of beta-lactams,cephalosporins and trimethoprim/sulfamethoxazole and quinolones and antibiotic resistance

E.coli

isolates.There are several limitations in this study,including insufficient data for uropathogens other than

E.coli

,in some cases,inconsistency of the antimicrobial susceptibility testing with clinical and laboratory standards and institute guidelines,and poor laboratory facilities.Furthermore,potential bias is that all of the samples were taken from patients in a referral hospital.

5.Conclusion

During the period of study,we found that

E.coli

isolates were the most common etiological agents among other uropathogens.Also,the prevalence of UTI was affected by different factors including gender,age,history of antibiotic exposure,and anatomical abnormalities.Furthermore,there was increasing resistance of

E.coli

isolates against some of the broad-spectrum antibiotics or first-line antibiotics between 2005 and 2010 years.Although the study found a highly significant association between risk factors UTI and antimicrobial resistance,it should be noted that many of complicated patients were referred from other hospital centers.Additionally,these patients were not the real representative of community-acquired UTIs,and more investigations should be performed for estimation of the resistance rate among common uropathogens.Therefore,we recommend that physicians should consider the increased resistance to ampicillin,oral cephalosporins and cotrimoxazole when they selected an antibiotic empirically for treatment of pediatric UTI.In this context,it’s important that local continuous studies of antimicrobial susceptibility at national and international levels are performed for the prevention of antimicrobial resistance.

Study concept and design

:Ali Reza Nateghian.

Data acquisition

:Sina Karaji.

Data analysis

:Sina Karaji,Khosrow Zamani.

Drafting of manuscript

:Khosrow Zamani.

Critical revision of the manuscript

:Ali Reza Nateghian.

The authors declare no conflict of interest.

Acknowledgment

We thank all the co-workers of the department of microbiology of the Ali Asghar Children Hospital,Tehran,Iran.