Chemotherapy Research and Practice

Chemotherapy Research and Practice / 2011 / Article

Research Article | Open Access

Volume 2011 |Article ID 218431 | https://doi.org/10.1155/2011/218431

Ziad Daoud, Claude Afif, "Escherichia coli Isolated from Urinary Tract Infections of Lebanese Patients between 2000 and 2009: Epidemiology and Profiles of Resistance", Chemotherapy Research and Practice, vol. 2011, Article ID 218431, 6 pages, 2011. https://doi.org/10.1155/2011/218431

Escherichia coli Isolated from Urinary Tract Infections of Lebanese Patients between 2000 and 2009: Epidemiology and Profiles of Resistance

Academic Editor: Spyros Pournaras
Received01 Jul 2011
Revised10 Aug 2011
Accepted13 Aug 2011
Published12 Oct 2011

Abstract

The purpose of this study was to investigate the bacterial etiology of urinary tract infections in one of the busiest hospitals of Lebanon and to examine the epidemiologic and microbiologic properties of Escherichia coli isolated from urinary tract infections of Lebanese patients over a 10-year period. Methods. This retrospective study analyzed the data generated between 2000 and 2009 (10,013 Gram-positive and Gram-negative bacteria). Bacterial identification was based on standard culture and biochemical characteristics of isolates. Antimicrobial susceptibility was tested by the disk diffusion method, and ESBL production was detected by synergy with third-generation cephalosporins and amoxiclav. Results. E. coli was the most frequent isolate throughout the ten years (60.64% of the total isolates). It was followed by Klebsiella pneumoniae and Proteus sp., Pseudomonas aeruginosa, Enterococcus sp., and Streptococcus agalactiae. E. coli occurred more frequently in women (69.8%) than in men (61.4%). The lowest percentage of susceptibility of E. coli was manifested against piperacillin and ampicillin. An increase in the production of ESBL was observed (2.3% in 2000 to 16.8% in 2009). Conclusions. The etiology of urinary tract infections and their susceptibility profiles are important to be evaluated in countries like Lebanon where a severe misuse of antibiotics at all levels is observed.

1. Introduction

Urinary tract infections (UTIs) are one of the most common infectious diseases [13]. They may be symptomatic or asymptomatic, and either type of infection can result in serious sequelae if not appropriately treated [4]. Although different causative agents can be responsible for UTIs, bacteria are the major cause being responsible for more than 95% of UTI cases [5]. In this context, E. coli is the most prevalent organism and is solely responsible for the majority of these infections. An accurate and prompt diagnosis is important in shortening the disease course and for preventing the ascent of the infection to the upper urinary tract [6]. Treatment of UTI is often started empirically. UTIs are often treated with different broad-spectrum antibiotics when one with a narrow spectrum of activity may be appropriate because of concerns about infection with resistant organisms, and antimicrobial susceptibility testing of the urinary pathogens constitutes the basis for antibiotic therapy. However, in view of the increasing bacterial resistance, regular monitoring of resistance patterns is necessary to improve guidelines for empirical antibiotic therapy [68]. The present study aims at analyzing the infectious epidemiology of UTIs in a general university hospital located in Beirut over a period of ten years. In addition, it examines the susceptibility profiles of E. coli between 2000 and 2009.

2. Material and Methods

2.1. Study Design

This is a retrospective study conducted at the Microbiology section of the Medical Laboratories of the Saint George Hospital-University Medical Center in Beirut and covering ten years (2000 to 2009). The population included all in- and outpatients with documented UTI. This included 10,013 different Gram-positive and Gram-negative bacteria in addition to Candida albicans and Candida sp. There were 6,708 (66.99%) samples from female patients and 3,305 (33.01%) from male patients. Adult patients were sampled by clean catch midstream urine, and children aged less than 3 years were sampled using sterile urine bags. Only a single positive culture per patient was included in the analysis within the period of three months.

2.2. Isolation and Identification of Organisms

Samples for urine culture were tested within half an hour of sampling. All samples were inoculated on blood agar as well as Mac Conckey agar and incubated at 37°C for 24 hours, and for 48 hours in negative cases. A specimen was considered positive for UTI in the light of the number of yielded colonies (≥105 cfu/mL) and the cytology of the urine through microscopic detection of bacteriuria and PMNs (≥8 leukocytes/mm3). However, lower colony counts associated with significant pyuria or low PMN count associated with significant colony counts was considered and analyzed in the light of the clinical picture and the patient’s immunological status. Bacterial identification was based on standard culture and biochemical characteristics of isolates.

Gram-negative bacteria were identified by standard biochemical tests [5, 6]. Gram-positive microorganisms were identified with the corresponding recommended laboratory tests.

2.3. Susceptibility Testing

Antimicrobial susceptibility of E. coli was tested by the disk diffusion method according to the CLSI recommendations, using the Mueller-Hinton agar [6]. Antimicrobial agents tested were ampicillin, amoxicillin-clavulanic acid, aztreonam, cephalothin, cefoxitin, cefuroxime, cefotaxime, ceftriaxone, ceftazidime, cefipime, piperacillin, piperacillin-tazobactam, imipenem, gentamycin, tobramycin, norfloxacin, ciprofloxacin, trimethoprim-sulfamethoxazole, and tetracycline. The CLSI-ESBL phenotypic confirmatory test with ceftazidime, cefotaxime, ceftriaxone, and cefixime was performed for all the isolates by disk diffusion method on the Mueller-Hinton agar plates with and without 10 μg of amoxiclav. Susceptibility test results were interpreted according to the criteria established by the Clinical & Laboratory Standard Institute (CLSI). A minimum of 5 mm increase in the zone of diameter of third-generation cephalosporins, tested in combination with amoxiclav versus its zone when tested alone, was considered indicative of ESBL production. E. coli ATCC 25922 was used as ESBL-negative and K. pneumoniae 700603 was used as ESBL-positive reference strain. Statistical analysis: variables were expressed as percentages.

3. Results

Over a 10-year period, a total of 10,013 positive urine isolates including 6,071 E. coli were analyzed.

Tables 1 and 2 show the microorganisms most frequently isolated from these positive urine cultures. As expected, E. coli was the most frequent isolate throughout the ten years (average of 60.64% of the total isolates). It was followed by Klebsiella pneumoniae where rate of isolation ranged between 6.1 and 9.9%. The next most frequently isolated bacteria were Proteus sp., Pseudomonas aeruginosa, Enterococcus sp., and Streptococcus agalactiae. Candida albicans and Candida sp. were commonly isolated; however, their clinical significance was not always evident. If Candida and minor bacterial isolates are not included, Gram-negative bacteria accounted for 92% of the UTI, while Gram-positive infections were responsible only for 8%.


The microorganisms most commonly isolated from Lebanese patients with UTI between 2000 and 2004
20002001200220032004
Nb%Nb%Nb%Nb%Nb%

Acinetobacter sp.30.540.520.200.0141.3
Candida albicans152.4121.6232.4262.4312.9
Candida sp.162.5222.9282.9474.3343.1
Citrobacter sp.60.9111.5192.0171.5151.4
Enterobacter sp.40.6121.6141.560.5161.5
Enterococcus faecalis172.7182.4282.9484.4201.9
Enterococcus faecium60.9182.4202.1302.7353.2
Escherichia coli39562.544058.357559.863757.966161.1
Klebsiella sp.487.6759.9596.1857.7797.3
Morganella morganii50.840.5111.1141.3141.3
Proteus sp.457.1506.6727.5746.7656.0
Pseudomonas aeruginosa304.7385.0454.7353.2514.7
Pseudomonas sp.00.020.310.110.100.0
Staphylococcus aureus30.560.830.370.690.8
Staphylococcus saprophyticus60.970.950.520.230.3
Streptococcus agalactiae203.2152.0141.5252.3181.7
Streptococcus, Group D10.220.340.410.160.6
Other minor organisms121.9192.5384.0454.1100.9

Total isolates63275596111001081


The microorganisms most commonly isolated from Lebanese patients with UTI between 2005 and 2009
20052006200720082009
Nb%Nb%Nb%Nb%Nb%

Acinetobacter sp.191.9141.2181.6161.350.5
Candida albicans141.4373.3272.4292.4252.5
Candida sp.292.9575.1343.0312.6353.5
Citrobacter sp.151.5181.6191.7161.390.9
Enterobacter sp.161.6222.0141.2191.660.6
Enterococcus faecalis141.4151.3201.8141.2151.5
Enterococcus faecium323.2252.2343.0342.860.6
Escherichia coli60960.271163.468860.772760.062862.5
Klebsiella sp.929.1847.51008.81189.7909.0
Morganella morganii131.360.5100.9242.070.7
Proteus sp.575.6534.7706.2736.0636.3
Pseudomonas aeruginosa393.9272.4403.5443.6414.1
Pseudomonas sp.00.060.500.060.530.3
Staphylococcus aureus70.740.460.540.3101.0
Staphylococcus saprophyticus00.050.410.120.230.3
Streptococcus agalactiae272.7141.2161.4161.380.8
Streptococcus, Group D10.110.110.100.010.1
Other minor organisms282.8232.0363.2383.1505.0

Total isolates10121122113412111005

Analysis of the results according to patient gender (not shown) indicated that although E. coli is the predominant isolated pathogen from both sexes, it occurred more frequently in women (69.8% in women compared to 61.4% in men.) The trend of infectious etiology in the population did not really differ over the 10-year period.

The percentages of susceptibility (and subsequently of nonsusceptibility including both resistant and intermediately resistant strains) of E. coli isolates to the panel of antibiotics which are commonly used to treat Escherichia infections are shown in Table 3. The lowest percentage of susceptibility was manifested against piperacillin (between 9 and 24%) followed by ampicillin (between 26 and 38%), whereas an absolute susceptibility was observed with imipenem (100%). In general, the urinary isolates showed a slightly better susceptibility profile in comparison to all the hospital isolates of E. coli. Over the successive years, the susceptibility to cephalosporins, including generations 3 and 4, tends to decrease; this is coupled by an increase in the production of ESBL as shown in Table 4 where ESBL production goes from 2.3% in 2000 to 16.8% in 2009 for the urinary isolates.


Percentages of susceptibility of E. coli isolated from Lebanese patients
YearSite of isolationNumberAntibacterial Agent
Ampicillin Amox-Clav Aztreonam Cephalothin Cefoxitin Cefuroxime Cefotaxim Ceftriaxone Ceftazidime Cefepime Piperacillin Pipera-Tazo Imipenem Gentamycin Tobramycin Norfloxacin Ciprofloxacin Trimeth-Sulfa

2000General6203758955492899696959720931008988757851
Urinary3953859985797959696979924941009289888354
Nonurinary2253556915281829595949617931008588597052
2001General6972856924991829393929518931008988757848
Urinary4403263945192889696979722941009289888351
Nonurinary2572249914789749189879213911008786617345
2002General9013062926096849494929612961008379647650
Urinary6993469946297909697979716971008680778153
Nonurinary202265489569377909187947931008177507345
2003General12212858815496838383828313951007874607748
Urinary6373265835697898990899017961008175738251
Nonurinary5162450785194777680747710941007574487244
2004General1094286552599577828282829991007881626564
Urinary66132725461968388898989131001008182757067
Nonurinary433255950569371757575747971007879526360
2005General9982661534995768080808110981007699586251
Urinary60930685551968286878788149910079100716754
Nonurinary389245551489372757372748971007499516049
2006General10722964795495808383838310991007999437149
Urinary711337181569686899090901410010082100567652
Nonurinary361256079559475797878788991007699397448
2007General10492965815995788181818110991008099444847
Urinary688347283619684878888881410010083100575350
Nonurinary361236080589373787777777991007899364544
2008General1098286677558973788080809991007593424745
Urinary7273067805596788288888915991008298625251
Nonurinary371256576548469757373735981007089394540
2009General10112660794696767979797913981007999444647
Urinary6283169814796848686875318991008399635251
Nonurinary3832353794596697474758011991007699354144


ESBL production in E. coli isolated between 2000 and 2009
20002001200220032004
IsolatesAllUNUAllUNUAllUNUAllUNUAllUNU

Number of isolates62039522569744025790169920212216375841094661433
% of ESBL2.32.12.343.94.39.89.99.513.614.512.112.911.014.1
20052006200720082009

IsolatesAllUNUAllUNUAllUNUAllUNUAllUNU

Number of isolates9986093891072711361104968836110987273711011628383
% of ESBL20.315.726.117.415.619.119.4519.219.819.417.122.018.616.821.8

Table 5 shows the susceptibility profiles of ESBL producing E. coli to families of antibiotics other than beta-lactams. Tigecycline, amikacin, and piperacillin-tazobactam seem to have the highest antibacterial activity on these organisms.


Percentages of susceptibility of ESBL producing E. coli
Antibacterial agent
YearIsolatesAmikacinCefoxitinGentamycinPip + TazoTSMTigecyclineCiprofloxacin

2005All90.585.629.897.639.4ND21.1
Urinary92.387.635.297.541.1ND16.4
Nonurinary88.283.525.197.837.1ND17.9
2006All97.980.727.393.324.1ND17.6
Urinary95.684.433.594.140.8ND18.8
Nonurinary98.376.922.193.518.9ND16.5
2007All93.681.430.192.223.589.623.1
Urinary91.287.522.489.936.891.225.7
Nonurinary90.275.636.895.441.393.219.1
2008All94.280.627.894.125.687.418.8
Urinary89.182.424.487.926.691.421.1
Nonurinary97.377.132.298.823.982.115.5
2009All93.683.430.894.219.591.619.6
Urinary94.684.536.196.625.494.419.5
Nonurinary91.882.226.392.210.689.919.2

Table 6 shows the percentages of simultaneous resistance in the urinary isolates of E. coli to various families of antimicrobial agents.


Percentage of resistance profiles
Resistance profile of urinary E. coli 20052006200720082009

Resistant to aminoglycosides and fluoroquinolones3.22.63.133.7
Resistant to 3rd-Generation cephalosporins and fluoroquinolones3.634.98.29.6
Resistant to 3rd-Generation cephalosporins and aminoglycosides3.93.43.52.53.1
Resistant to 3rd-Generation cephalosporins, aminoglycosides, and fluoroquinolones8.799.813.87.3

4. Discussion

This study shows the distribution of microbial species and antibiotic susceptibility patterns of E. coli isolated from Lebanese patients with UTIs. Saint George Hospital is a 300-bed hospital located in Beirut; however, it is one of the busiest hospitals in the country and receives patients from different areas of Lebanon. In this retrospective study, no clinical data are provided, and this constitutes by itself a limitation. Subsequently, important information related to symptomatic versus asymptomatic, complicated versus uncomplicated UTI, and health-care-associated versus catheter-related UTIs could not be addressed and discussed. The majority of pathogens were isolated from women (69.8%). It has been extensively reported that adult women have a higher prevalence of UTI than men, principally owing to anatomic and physical factors [9].

Antibiotic resistance is a major clinical problem in treating infections caused by these microorganisms. The resistance to the antimicrobials has increased over the years. Resistance rates vary from country to country [10]. In Lebanon, there is an evidence for increase in ESBL producing Enterobacteriaceae. This was previously reported in our hospital as well as in other institutions in the country [1115]

In this study, E. coli accounted for approximately 61% of all clinically significant urinary isolates and 76.8% of all Enterobacteriaceae. This is consistent with the findings of previous studies in which E. coli was the predominant pathogen isolated from patients with UTIs [16, 17]. The rate of isolation of Klebsiella pneumoniae might be described as high when compared to other studies [16, 17]; however, this can be explained by the fact that our study includes both hospital and acquired UTI.

E. coli isolates from urinary infections show a similar pattern of susceptibility to those isolated from all body site infections although with a more enhanced susceptibility percentages. Aminopenicillins do not constitute a therapeutic option in this population; even the combination amoxicillin-clavulanic acid does not seem to offer important alternative for treatment. In view of the increasing ESBL production, all cephalosporins activities are affected and challenged by these inactivating enzymes. Imipenem remains the only antibiotic with 100% of susceptibility.

It is pretty alarming to note that between 7.3 and 13.8% of the urinary isolates of E. coli show simultaneous resistance to third-generation cephalosporins, aminoglycosides, and fluoroquinolones. A genetic investigation on these isolates should be performed in order to identify the mechanisms of resistance and discover whether they are correlated to each other or independently occurring.

Conflict of Interests

The authors declare that they have no conflict of interests.

References

  1. A. Hoberman and E. R. Wald, “Urinary tract infections in young febrile children,” Pediatric Infectious Disease Journal, vol. 16, no. 1, pp. 11–17, 1997. View at: Publisher Site | Google Scholar
  2. J. R. Delanghe, T. T. Kouri, A. R. Huber et al., “The role of automated urine particle flow cytometry in clinical practice,” Clinica Chimica Acta, vol. 301, no. 1-2, pp. 1–18, 2000. View at: Publisher Site | Google Scholar
  3. K. Hryniewicz, K. Szczypa, A. Sulikowska, K. Jankowski, K. Betlejewska, and W. Hryniewicz, “Antibiotic susceptibility of bacterial strains isolated from urinary tract infections in Poland,” Journal of Antimicrobial Chemotherapy, vol. 47, no. 6, pp. 773–780, 2000. View at: Google Scholar
  4. M. Pezzlo, “Detection of urinary tract infections by rapid methods,” Clinical Microbiology Reviews, vol. 1, no. 3, pp. 268–280, 1988. View at: Google Scholar
  5. M. Bonadio, M. Meini, P. Spitaleri, and C. Gigli, “Current microbiological and clinical aspects of urinary tract infections,” European Urology, vol. 40, no. 4, pp. 439–445, 2001. View at: Publisher Site | Google Scholar
  6. Clinical and Laboratory Standards Institute, “Performance standards for antimicrobial susceptibility testing,” CLSI document M100-S15, Clinical and Laboratory Standards Institute, Wayne, Pa, USA, 15th International supplement, 2005. View at: Google Scholar
  7. N. Grude, Y. Tveten, and B. E. Kristiansen, “Urinary tract infections in Norway: bacterial etiology and susceptibility. A retrospective study of clinical isolates,” Clinical Microbiology and Infection, vol. 7, no. 10, pp. 543–547, 2001. View at: Publisher Site | Google Scholar
  8. C. Kripke, “Duration of therapy for women with uncomplicated UTI,” American Family Physician, vol. 72, no. 11, 2005. View at: Google Scholar
  9. M. Kumar, V. Lakshmi, and R. Rajagopalan, “Occurrence of extended spectrum β-lactamases among Enterobacteriaceae spp. isolated at a tertiary care Institute,” Indian Journal of Medical Microbiology, vol. 24, no. 3, pp. 208–211, 2006. View at: Google Scholar
  10. N. R. Kahan, D. P. Chinitz, D. A. Waitman, D. Dushnitzky, E. Kahan, and M. Shapiro, “Empiric treatment of uncomplicated urinary tract infection with fluoroquinolones in older women in Israel: another lost treatment option?” Annals of Pharmacotherapy, vol. 40, no. 12, pp. 2223–2227, 2006. View at: Publisher Site | Google Scholar
  11. S. S. Kanj, J. E. Corkill, Z. A. Kanafani et al., “Molecular characterisation of extended-spectrum β-lactamase-producing Escherichia coli and Klebsiella spp. isolates at a tertiary-care centre in Lebanon,” Clinical Microbiology and Infection, vol. 14, no. 5, pp. 501–504, 2008. View at: Publisher Site | Google Scholar
  12. Z. Daoud, C. Moubareck, N. Hakime, and F. Doucet-Populaire, “Extended spectrum β-lactamase producing enterobacteriaceae in lebanese ICU patients: epidemiology and patterns of resistance,” Journal of General and Applied Microbiology, vol. 52, no. 3, pp. 169–178, 2006. View at: Publisher Site | Google Scholar
  13. C. Moubareck, Z. Daoud, N. I. Hakimé et al., “Countrywide spread of community- and hospital-acquired extended-spectrum β-lactamase (CTX-M-15)-producing Enterobacteriaceae in Lebanon,” Journal of Clinical Microbiology, vol. 43, no. 7, pp. 3309–3313, 2005. View at: Publisher Site | Google Scholar
  14. G. M. Matar, S. Al Khodor, M. El-Zaatari, and M. Uwaydah, “Prevalence of the genes encoding extended-spectrum β-lactamases, in Escherichia coli resistant to β-lactam and non-β-lactam antibiotics,” Annals of Tropical Medicine and Parasitology, vol. 99, no. 4, pp. 413–417, 2005. View at: Publisher Site | Google Scholar
  15. Z. Daoud and N. Hakime, “Prevalence and susceptibility patterns of extended-spectrum betalactamase-producing Escherichia coli and Klebsiella pneumoniae in a general university hospital in Beirut, Lebanon,” Revista Espanola de Quimioterapia, vol. 16, no. 2, pp. 233–238, 2003. View at: Google Scholar
  16. C. A. McNulty, J. Bowen, G. Clark, A. Charlett, and K. Cartwright, “How should general practitioners investigate suspected urinary tract infection? Variations in laboratory-confirmed bacteriuria in South West England,” Communicable Disease and Public Health, vol. 7, no. 3, pp. 220–226, 2004. View at: Google Scholar
  17. G. Kahlmeter, “Prevalence and antimicrobial susceptibility of pathogens in uncomplicated cystitis in Europe. The ECO. SENS study,” International Journal of Antimicrobial Agents, vol. 22, no. 2, pp. S49–S52, 2003. View at: Publisher Site | Google Scholar

Copyright © 2011 Ziad Daoud and Claude Afif. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


More related articles

 PDF Download Citation Citation
 Download other formatsMore
 Order printed copiesOrder
Views25255
Downloads1314
Citations

Related articles

We are committed to sharing findings related to COVID-19 as quickly as possible. We will be providing unlimited waivers of publication charges for accepted research articles as well as case reports and case series related to COVID-19. Review articles are excluded from this waiver policy. Sign up here as a reviewer to help fast-track new submissions.