Manuscript accepted on :March 14, 2016
Published online on: 25-04-2016
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Balaji Chinnasami*, Subha Sundaramoorthy , Kanimozhi Sadasivam and Sekar Pasupathy
SRM Medical College, Hospital and RC, Potheri, Kattankulathur, India. Corresponding Author Email : balajictriumphants@gmail.com
DOI : https://dx.doi.org/10.13005/bpj/949
Abstract
To identify common microbes causing urinary tract infection in pediatric population and their resistance pattern to commonly used antibiotics in a south Indian hospital. We retrospectively collected urine culture and sensitivity data of children admitted with suspected urinary tract infection from January 2015 to December 2015. Antimicrobial susceptibility testing was performed by antibiotic disc diffusion method and ESBL production confirmed by Double disk synergy test. About 130 were culture positive with E.coli being the predominant microbe grown (40.8%) and ESBL production was high to the tune of 83% in them. Most Gram negative bacteria were sensitive to aminoglycosides and carbapenams and Gram positive bacteria were susceptible to Vancomycin and Linezolid. ESBL mpositiveE.coli was resistant to many drugs including Penicillins, Cephalosporins and Quinolones. Nitrofurantoin elicited good invitro response to ESBL positive E.coli, Enterococcus and Coagulase Negative Staphylococcus. Our study shows that E.coli is the most common cause of urinary tract infection and since 80% are ESBL producers they are multidrug resistant. Oral Nitrofurantoin is a good choice for uncomplicated urinary tract infection. Parenteral aminoglycosides, Piperacillin/Tazobactum, Cefoperazone/Sulbactum can be recommended for complicated UTI reserving carbapenams for those cases who don’t respond to initial theraphy.
Keywords
Antibiotic resistance; ESBL; E.coli; Klebsiella; Proteus; nitrofurantoin
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| Copy the following to cite this article: Chinnasam B, Sundaramoorthy S, Sadasivam K, Pasupathy S. Pathogens Causing Urinary Tract Infection In Children and Their In Vitro Susceptibility to Antimicrobial Agents- A Hospital Based Study. Biomed Pharmacol J 2016;9(1) |
| Copy the following to cite this URL: Chinnasam B, Sundaramoorthy S, Sadasivam K, Pasupathy S. Pathogens Causing Urinary Tract Infection In Children and Their In Vitro Susceptibility to Antimicrobial Agents- A Hospital Based Study. Biomed Pharmacol J 2016;9(1). Available from: http://biomedpharmajournal.org/?p=6805 |
Introduction
Urinary tract infection (UTI) is one of the most common infections in children associated with significant complications like scarring of kidney, hypertension, and chronic kidney disease1. Gram-negative bacilli are the most common cause of pediatric UTI especially Escherichia coli responsible for more than 90% of uncomplicated UTI2. Enterococcus, Klebsiella and Coagulase negative Staphylococcus aureus (CoNS) are other organisms sharing remaining burden of UTI. Antibiotics have been the mainstay of treatment of UTI. Antibiotic resistance has become a major global problem especially in India where 80% of E.coli is resistant to penicillins, cephalosporins and quinolones (http://www.cddep.org/resistancemap/). Treatment of UTI is becoming difficult because of the antibiotic resistance in bacteria especially with E.coliproducing extended spectrum ß-lactamases (ESBLs). Our study aims to identify common pathogens causing UTI in children, their in vitro antibiotic susceptibility pattern to commonly used antibiotics in a clinical setting in India. These findings will help us in deciding the empirical choice of antibiotics for children presenting with UTI, thus preventing treatment failure and decreasing the drug resistance rates.
Table 1: Number and proportion of isolated pathogens (Gram negative and Gram positive pathogen) from midstream urine species
| Gram negative bacteria | Gram positive bacteria | ||||
| Bacteria Species | n | Percent | Bacteria Species | n | Percent |
| Escherichia coli | 53 | 40.8% | Enterococcus species | 29 | 24.6 % |
| Klebsiella species | 22 | 17 % | Coagulase Negative Staphylococcus (CoNS) | 5 | 3.8% |
| Proteus species | 14 | 10.8% | |||
| Enterobacter species | – | ||||
| Pseudomonas aeruginosa | 4 | 3.1% | |||
| Acinetobacter species | 1 | 0.8% | |||
Design and setting
It was a retrospective observational study collecting data from hospital records during the period of January 2015 – December 2015 in SRM medical college hospital & research centre. Urine culture reports of all pediatric patients with suspected UTI admitted in SRM hospital during that period were reviewed.
Inclusion criteria All children with suspected UTI and whose urine culture shows single pathogen with colony counts higher than or equal to 105 colony forming units (CFU)/ml were included for the study.
Table 2: The distribution of pathogens in patients according to gender
| Boys | Girls | |||
| Bacteria
|
Number of patients | Percent | Number of
patients |
Percent
|
| Escherichia coli | 23 | 43.4 % | 30 | 56.6 % |
| Klebsiella species | 20 | 59.1 % | 9 | 40.9 % |
| Proteus species | 14 | 100 % | – | – |
| Enterobacter species | – | – | – | – |
| Pseudomonas aeruginosa | –
|
– | – | – |
| Acinetobacter species | 1 | 100 % | – | – |
| Enterococcus species | 20 | 69 % | 9 | 31.03 % |
| Coagulase Negative Staphylococcus (CoNS) | 02 | 40% | 3 | 60% |
Exclusion Criteria Results of urine cultures without growth, multiple pathogens in urine culture, colony counts less than 105 colony forming units (CFU)/ml were excluded from the study.
Antibiotics and reagents
Urine culture was done semi-quantitatively on 5% sheep Blood Agar and MacConkey Agar plates incubated at 37°C overnight. Standard technique for semi-quantitative culture of urine was applied for colony count. After identification of organism antimicrobial susceptibility testing of the bacterial isolates was performed by Kirby Bauer’s disk diffusion method using commercial antibiotic disks (Himedia, India) as per the Clinical and Laboratory Standards Institute (CLSI) guidelines3. The list of antibiotics used was appropriate for the urine sample and the type of organism (Gram positive/gram negative). ESBL-producing E.coli, were detected using a double-disc synergy test.
It included Ampicillin (10µg), Amikacin (30µg), amoxicillin/ clavulanic acid (30µg+10µg), Cefotaxime (30µg), Cefepime (30µg), Ceftazidime (30µg), Ceftazidime+Clavulanic acid (30µg+10µg), Cefeperazone/sulbactam (75/30µg), Cefpodoxime (10µg), Ceftriaxone (30µg), Cefuroxime (30µg), Cefoxitin (30µg), Ciprofloxacin (5µg), Co-trimoxazole (25µg), Gentamicin (10µg), Imipenem (10µg), Meropenem (10µg), Nitrofurantoin (300µg), Norfloxacin (10µg), Ofloxacin (5µg), Piperacillin/Tazobactam(100µg).
The Eschericia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853 , Staphylococcus aureusATCC 29213, Enterococcus faecalisATCC 29212 strains were used as controls for the susceptibility testing of Enterobacteriacea, Nonfermenters, Staphylococcus species and Enterococcus species respectively. The interpretation of the zone diameters was done as per the CLSI break points13.
Table 3: Antibiotic susceptibility test results to antibiotics commonly used against ESBL- positive and ESBL-negative Escherichia coli
|
ESBL-positive Escherichia coli (n= 44) |
ESBL-negative Escherichia coli (n= 9) | |||||
| Antimicrobial drug | S% | I% | R% | S% | I% | R% |
| Imipenem | 42(95.5) | – | 2(4.5) | 9 (100) | – | – |
| Ciprofloxacin | 2 (4.5) | 1(2.3) | 41(93.2) | 7 (77.8) | – | 2 (22.2) |
| Nitrofurantoin | 40(90.9) | – | 4(9.1) | 8 (88.9) | – | 1 (11.1) |
| Meropenem | 42 (95.5) | – | 2 (4.5) | 9(100) | – | – |
| AmoxycillinClavulanic acid | – | – | 44 (100) | 3 (33.3) | – | 6 (66.7) |
| Amikacin | 42 (95.5) | 1(2.3) | 1(2.3) | 9 (100) | – | – |
| Gentamicin | 42(95.5) | – | 2(4.5) | 9 (100) | – | – |
| cefazolin | – | – | 44 (100) | 6 (66.7) | 1(11.1) | 2(22.2) |
| cefepime | 4(9.1) | 1(2.3) | 39(88.6) | 3 (33.3) | – | 6 (66.7) |
| cefotaxime | – | – | 44(100) | 9 (100) | – | – |
| Ceftazidime | – | – | 44 (100) | 9 (100) | – | – |
| cefuroxime | 1(2.3) | – | 43(97.7) | 9 (100) | – | – |
| Colistin | 44 (100) | – | – | 9 (100) | ||
| Ertapenem | 43 (97.7) | – | 1(2.3) | 9 (100) | – | – |
| Nalidixic acid | – | – | 44(100) | 2 (22.2) | – | 7 (77.8) |
| Netilmycin | 41(93.2) | 1(2.3) | 3(6.8) | 9 (100) | – | – |
| Norfloxacin | 13(29.5) | – | 31(70.5) | 9 (100) | – | – |
| Piperacillin/Tazobactum | 34(77.3) | 3(6.8) | 7(15.9) | 9 (100) | – | – |
| Co-trimoxazole | 8(18.2) | – | 38(86.4) | 4 (44.4) | – | 5 (55.5) |
| Ampicillin | – | – | 44 (100) | 3 (33.3) | – | 6 (66.7) |
| Ceftriaxone | 1 (2.3) | 43 (97.7) | 9(100) | – | – | |
| Cefaperazonesulbactum | 38(86.4) | 3 (6.8) | 3 (6.8) | 9 (100) | – | – |
*S%- Percentage sensitive, I%- Percentage Intermediate Sensitive, R%- Percentage Resistant
Results
About 551 urine samples from suspected UTI children were subjected to culture and antibiotic susceptibility testing by Kirby Bauer Disc diffusion method. About 130 were culture-positive, had significant colony count and included in the final analysis. E coli was detected in 40.8 % of cultures, followed by Enterococcus spp (22.3%), Klebsiellaspp (17.0%), Proteus spp (10.8%), Coagulase negative Staphylococcus (3.8%), Pseudomonas (3.1%), and Acinetobacter (0.8%). The detection rate of ESBL-producing E coli was 83%. E.coli&Klebsiella were almost equally distributed among both sexes but all cases of Proteus and most cases of Enterococcus (69%) occurred in males.
Most Gram negative bacteria were sensitive to Aminoglycosides and Carbapenams and Gram positive bacteria were sensitive to Vancomycin and Linezolid. ESBL positive E.coli was more problematic with resistance to Amoxycillin/clavulanic acid, Cephalosporins and Quinolones. They were also not uniformly sensitive to Piperacillin/Tazobactum (77.3%), Cefoperazone/Sulbactum (86.4%) as ESBL negative E.Coli.Nalidixic acid resistance which is considered as a marker of fluoroquinolone resistance ranges from 100% in ESBL positive E.colito 25% in Klebsiella. The surprise drug has been Nitrofurantoin with ESBL positive E.coli, Enterococcus & Coagulase Negative Staphylococcus being sensitive. Not only in ESBL positive E.coli, cephalosporin resistance was observed one in three times in Klebsiella and 80% resistance to Cefazolin was seen in Proteus. Also Trimethoprim/Sulfamethoxazole resistance was high in the range of 35%-86% among various enterobacteraciaea.
Table 4 : Antibiotic susceptibility test results to antibiotics commonly used against Klebsiellasppand Proteus spp.
|
Antimicrobial drug |
Klebsiellaspp, n= 22 | Proteus spp, n=14 | |||||
| S% | I% | R% | S% | I% | R% | ||
| Imipenem | 21 (95.5) | 1 (4.5) | – | 14 (100) | _ | – | |
| Ciprofloxacin | 21(95.5) | – | 1(4.5) | 9 (64.3) | 2 (14.3) | 3 (21.4) | |
| Nitrofurantoin | 13 (59.1) | 7 (31.8) | 2 (9.1) | 7 (50) | 2 (14.3) | 5(35.7) | |
| Meropenem | 22 (100) | – | – | 14 (100) | – | – | |
| Amikacin | 21(95.5) | – | 1(4.5) | 13 (92.9) | 1 (7.1) | – | |
| Gentamicin | 21(95.5) | – | 1(4.5) | 14(100) | – | – | |
| Cefazolin | 13 (59.1) | – | 9 (40.9) | 14 (100) | – | – | |
| Cefepime | 14 (63.6) | 1(4.5) | 7(31.8) | 3 (21.4) | 2 (14.3) | 9(64.3) | |
| Cefotaxime | 14(63.6) | – | 8(36.4) | 11(78.6) | – | 3(21.4) | |
| Ceftazidime | 14(63.6) | – | 8(36.4) | 12 (85.7) | – | 2 (14.3) | |
| Cefuroxime | 15(68.2) | – | 7(31.8) | 14 (100) | – | – | |
| Colistin | 11(50) | – | – | 7(50) | 4(18.2) | 3(21.4) | |
| Ertapenem | 21(95.5) | – | 1(4.5) | 14(100) | – | – | |
| Nalidixic acid | 15 (68.2) | 2(9.1) | 5(22.7) | 9(40.9) | 1(7.1) | 4(18.2) | |
| Netilmycin | 20 (90.9) | 1(4.5) | 1 (4.5) | 13(92.9) | – | 1 (7.1) | |
| Norfloxacin | 18(81.8) | 3(13.6) | 1(4.5) | 11(78.6) | 1(7.1) | 2(14.3) | |
| Piperacillin/Tazobactum | 19(86.4) | 2(9.1) | 1(4.5) | 14 (100) | – | – | |
| Co-trimoxazole | 14(63.6) | – | 8(36.4) | 4(28.6) | 1(7.1) | 9(64.3) | |
*S%- Percentage sensitive, I%- Percentage Intermediate Sensitive, R%- Percentage Resistant
Discussion
This studydescribes one year susceptibility pattern of microorganisms causing UTI in pediatric population in SRM hospital. Male preponderance (62%) was there in our study. E.coli (40.8%) was the most common bacteria grown followed by Enterococcus (24.6%) and Klebsiella (17.0%). Studies done earlier also suggest a similar pattern4-6. However in our study 83% of E.coliwere ESBL producers, higher than what has been reported by other studies.
E.coli treatment options
E.coli arising from gut flora and causing UTI is a real challenge to clinicians because of the production of ESBL. Due to indiscriminate usage of antibiotics, E.coli in the gut are exposed to multiple drugs and due to selective pressure develop resistance against them. Plasmids transmit such drug resistance genes to remaining bacteria7. Our susceptibility results suggest that ESBL positive E.coliare resistant to more number of commonly used antibiotics than ESBL negative E.coli.
We are now facing a situation where we don’t have a good oral antibiotic against E.coli with no option of quinolones, cephaosporins and penicillins. One ray of hope is orally available Nitrofurantoin which is still sensitive against ESBL positive E.coli(91%). At present Nitrofurantoin can be given empirically for uncomplicated UTIs but studies related to its efficacy in complicated UTI is not convincing.
Aminoglycosides can be recommended as initial empiric choice parenterally for ESBL positive E.colialthough nephrotoxic potential has to be kept in mind. Usually a resistance of 20% is taken as the threshold for changing the empirical treatment of UTI8. Based on this recommendation, eventhoughPiperacillin/Tazobactum (15.9% resistance) and Cefoperazone/Sulbactum (6.8% resistance) are not uniformly sensitive, still can be recommended as first choices for ESBL positive E.coli. Carbapenams should be reserved as the final choice when patients fail to respond to the above antibiotics.
Table 5 : Antibiotic susceptibility test results to antibiotics commonly used against CoNSand Enterococcus spp
| CoNS , n= 5 | Enterococcus spp, n=29 | ||||||
| Antimicrobial drug | S% | I% | R% | Antimicrobial drug | S% | I% | R% |
| Amikacin | 5 (100) | – | – | Ampicillin | 20 (69) | 3(10.3) | 6(20.7) |
| Cefazolin | 4 (80) | – | 1(20) | Gentamicin (High level) | 14(48.3) | – | 15(51.7) |
| Ciprofloxacin | 2(40) | – | 3(60) | Linezolide | 28(96.6) | – | 1(3.4) |
| Gentamicin | 5(100) | – | – | Nitrofurantoin | 26(89.7) | 1(3.4) | 1(3.4) |
| Linezolide | 5(100) | – | – | Penicillin | 21(72.4) | – | 8(27.6) |
| Nitrofurantoin | 5(100) | – | – | Tetracyclin | 28(96.6) | 1(3.4) | – |
| Norfloxacin | 5(100) | – | – | Vancomycin | 26(89.7) | 2(6.9) | 1(3.4) |
| Penicillin | – | – | 5(100) | ||||
| Rifampicin | 5(100) | – | – | ||||
| Tetracyclin | 4(80) | 1(20) | – | ||||
| Cotrimoxzole | 2(40) | 1(20) | 2(40) | ||||
| Vancomycin | 5(100) | – | – | ||||
*S%- Percentage sensitive, I%- Percentage Intermediate Sensitive, R%- Percentage Resistant CoNS- Coagulase Negative Staphylococcus
Klebsiella treatment options
Nine percentage resistance with Nitrofurantoin makes it an oral option for UTI due to Klebsiella. Quinolones may be recommended with caution because Norfloxacin(4.5%) resistance is low but Nalidixic acid resistance (22.7%) is higher. Few patients may not respond invivo to quinolones. Cephalosporins are poor choices as more than 30% resistance to cephalosporins is seen. Aminoglycosides and Piperacillin/Tazobactum should be the empiric first choice parenteral antibiotics.
Proteus treatment options
Resistance to Nitrofurantoin (35.7%) is high and hence cannot be recommended as an oral option but AmoxycillinClavulanic acid can be tried orally since it is 100% sensitive. Aminoglycosides, Cefazolin and Piperacillin/Tazobactum should be the empiric parenteral choices.
Gram positive bacteria- treatment options
Coagulase Negative Staphylococcus (CONS) and Enterococcus were highly sensitive to Nitrofurantoin, Linezolid and Vancomycin. Hence uncomplicated UTI may be treated with oral Nitrofurantoin and complicated ones with parenteral Vancomycin and Linezolid.
Combating antibiotic resistance
The last time when an antibiotic was approved for gram negative sepsis was in 1973 and it was trimethoprim/sulfamethoxazole. Our research is unable to catch the pace at which bacteria are relentlessly developing resistance. With no new antibiotic classes in the near future it is just a matter of time that they will develop resistance against all current options also.
One option for combating resistance will be to explore promising drugs like fosfomycin, cycloserine and include them in our armamentarium. Fosfomycin is a phosphonic acid with broad spectrum Gram positive and Gram negative activity including Methicillin Resistant Staphylococcus Aureus (MRSA), Vancomycin Resistant Enterococcus (VRE) and Pseudomonas used often in Europe and US9, 10. However it has not yet been included in the list of antibiotics for susceptibility testing. Cycloserine which is used as second option for tuberculosis has been explored previously for UTI11. Since limited studies are available cycloserine can be studied further as an oral option.
Other strategies like vaccination with orally administered UrovaxonR 12 and parenteral StrovacR 13, Probiotics15, Immune drugs14 should be further researched as relying only on antibiotics may lead to disaster in the near future. Till then judicious and rational use of antibiotics based on culture and susceptibility patterns should be recommended.
Conclusion
Our study shows that ESBL producing E.coli is the major pathogen causing UTI among pediatric population. Major cause of concern is that most of the organisms grown are resistant to three or more antibiotics. Oral Nitrofurantoin seems to be a promising oral option for uncomplicated UTI. Parenteral aminoglycosides, Piperacillin/Tazobactum and Cefoperazone/ Sulbactum can be given as first choice for Gram negative bacteria and parenteral Vancomycin, Linezolid for Gram positive bacteria. Carbapenams should be kept as reserve for patients who fail to respond with first choice antibiotics. Strict hospital antibiotic stewardship program should be in place which routinely reviews culture and susceptibility patterns and optimizes the selection and dosing accordingly.
Conflict of interest: None
Source of funding
Self- funded project
Acknowledgement
We sincerely thank the head of the department Microbiology, Dr. S. Gomathi, for making the data available to us.
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