Home | Volume 28 | Article number 258

Original article

Bacteriological profile and antimicrobial susceptibility patterns of urine culture isolates from patients in Ndjamena, Chad

Bacteriological profile and antimicrobial susceptibility patterns of urine culture isolates from patients in Ndjamena, Chad

Michel Kengne1,&, Amon Todjimbaide Dounia1,2, Julius Mbekem Nwobegahay1,3

 

1Department of Medical Microbiology and Immunology, School of Health Sciences-Catholic University of Central Africa, Yaoundé, Cameroon, 2Ndjamena General Hospital of National Reference, Chad, 3Yaoundé Military Hospital, Cameroon

 

 

&Corresponding author
Michel Kengne, Department of Medical Microbiology and Immunology, School of Health Sciences-Catholic University of Central Africa, Yaoundé, Cameroon

 

 

Abstract

Introduction: bacteriological profile and antimicrobial susceptibility patterns of urine culture isolates were determined among patients in the Ndjamena General Hospital, a National Reference centre.

 

Methods: a cross-sectional study was carried out from July to November 2014. Six hundred and sixty patients were enrolled, to whom a cytobacteriological examination of urine was prescribed. Urine was collected and cultured. Bacterial identification and antimicrobial susceptibility patterns were performed using Vitek 2 compact automated system.

 

Results: 216 isolates were recovered from patients (age range: 10-90 years). E. coli was the pathogen frequently cultured 128 (59.3%) followed by K. pneumonia 28 (13.0%). Bacteriuria was more present in inpatients (70.4%) compared to outpatients (29.6%). High antibiotic-resistance rate (> 60%) of the total isolates was observed with ampicillin, ciprofloxacin and cephalosporins. Imipeneme (94.9%) displayed satisfactory activity against bacteria isolates. ESBLs phenotype was present in 68/105 (64.7%) of betalactamine resistant isolates. AAC(3)-I and AAC(6’)-I enzymes were found respectively in 16/36 (44.4%) and 20/36 (55.6%) of aminoglycosides resistant isolates. Resistance of isolates to quinolones was mainly due to an association of target modification (gyrA and parC), porin reduction and/or efflux mechanisms and was present in 107/213 (49%) of quinolones resistant isolates.

 

Conclusion: E. coli is the predominant uropathogen isolated in our setting and there are antibiotic-resistant uropathogens among the studied population. Therefore, routine surveillance of bacterial uropathogens to common used antibiotics must be a continuous process so as to provide physicians with up to date information about the local data of antimicrobial resistance.

 

 

Introduction    Down

Urinary tract infections (UTIs) are the third most common infection in human with an estimated annual global incidence of at least 250 million in developing country [1-3]. Different microorganisms can cause UTIs, E. coli which accounts approximately for 75% of isolates is the most common pathogen isolated from community and hospital acquired UTIs [4]. Other uropathogens such as Klebsiella spp. and S. saprophyticus have also been frequently isolated [5, 6]. The management of UTIs is usually empirical, based on the predictable spectrum of etiologic agents and their susceptibility patterns. Due to the emergence of antimicrobial resistance among uropathogens, the effectiveness of empirical therapy has been affected [7]. In Chad, antimicrobial susceptibility among pathogens involved in UTIs is poorly investigated. Therefore, it is important to obtain information on local antimicrobial resistance rates to provide adequate treatment to community and hospital acquired UTIs in this country. In this study, we investigated the bacteriological profile and the antimicrobial susceptibility patterns of urine culture isolates among patients in Ndjamena General Hospital of National Reference.

 

 

Methods Up    Down

Patients: the study participants were both inpatients and outpatients attending the Ndjamena General Hospital of National Reference from July to November 2014. Six hundred and sixty patients to whom a cytobacteriological examination of urine was prescribed and who had not received antimicrobials within the previous fifteen days were eligible for inclusion.

 

Bacterial isolation, identification procedures and antimicrobial susceptibility testing: a freshly midstream morning urine sample of 2-5ml was collected in sterile container from the selected patients. Aseptic measures were maintained during samples collection. Immediately after sampling, urine was spread on Eosin Methylene Blue agar media and incubated at 37°C for 24h. A growth of > 105 CFU/ml of one type of organism was considered as significant bacteriuria. Identification of the pathogens and antimicrobial testing were performed using Vitek 2 compact automated system (bioMérieux, Marcy l’étoile, France) according to the manufacturer’s instructions.

 

The results were recorded as susceptible (S), susceptible dose dependent (SDD) and resistant (R). The following antibiotics purchased from bio-Mérieux (France) were used: amoxicillin/ clavulanic acid (20/10µg), ampicillin (10µg), oxacillin (5µg), ceftriaxone (30µg), ceftazidime (30µg), cefotaxime (30µg), aztreonam (30µg), imipenem (10µg), gentamycin (15µg), amikacin (30µg), nalidixic acid (30 µg), ciprofloxacin (5µg), ofloxacin (5µg). The reference strain used as quality control was E. coli (ATCC 25922).

 

Data analysis: data were entered and analyzed using SPSS version 12.0 for windows (SPSS, Inc., Chicago, IL). Discrete variables were expressed as frequencies and percentages.

 

Ethics: permission to collect samples was obtained from the Ndjamena General Hospital of National Reference. Informed consent was obtained from all participants ≥ 18 years, while assent consent was obtained from participant teenagers via a proxy.

 

 

Results Up    Down

From July to November 2014 (05 months study period), 660 urine samples were obtained from patients (age range: 10-90 years) and analyzed. 216 (32.7%) samples had significant bacteriuria among which 94 (43.5%) positive samples were from women and 122 (56.5%) were from men (sex ratio M/F: 1.29). Bacteriuria was more present in inpatients 152/216 (70.4%) compared to outpatients 64/216 (29.6%). The most frequent pathogen was E. coli 128 (59.2%), followed by K. pneumonia 28 (13.0%) and E. cloacae 11 (5.1%) which altogether accounted for 77.3% of the total isolates (Table 1). Bacterial uropathogen isolates from patients revealed the presence of high level of single and multiple antimicrobial resistances against commonly prescribed drugs. The total isolates displayed a resistance rate of > 60% to the antibiotics used excepted imipéneme, amikacin, aztreonam and gentamicin for which the resistance rates were 2.7%, 19.4%, 30.5% and 49.5% respectively. E.coli which is the predominant cause of UTIs in this study was susceptible to imipeneme 96.1%, aztreonam 67.1%, amikacin 62.5% and gentamycin 50%. As E. coli, K. pneumonia and E. cloacae were the most important uropathogens isolated and their susceptibility rates are displayed in Table 2.

 

Furthermore, the remainder of this report will consider only these organisms. Betalactame-type enzymes production which determines variable phenotypes of betalactamines resistance was observed among the isolates. Extended spectrum betalactamases (ESBLs) that hydrolyze extended-spectrum cephalosporins (cefotaxime, ceftriaxone, ceftazidime) and monobactams (aztreonam) were present in 68/105 (64.7%) of betalactamines resistant isolates followed by cephalosporinase overproducing phenotype 27/105 (25.7%). Aminoglycosides resistance through enzymatic production was also recorded. Aminglycoside-acetyltransferases AAC(3)-I and AAC(6’)-I phenotypes were found respectively in 16/36 (44.4%) and 20/36 (55.6%) of aminoglycosides resistant isolates, thereby explaining the resistance phenotypes observed with gentamycin and amikacin. On the other hand, phenotypes associated with quinolones resistant isolates were produced through natural resistance and acquired resistance through non enzymatic drug resistance mechanisms. Resistance of isolates to quinolones was mainly due to an association of target modification (gyrA and parC), porin reduction and/or efflux mechanism which was present in 107/213 (49%) of quinolones resistant isolates, wild type phenotype was found in 60/213 (28%) of quinolone resistant isolates (Table 3).

 

 

Discussion Up    Down

Knowledge of the etiology and the antimicrobial resistance patterns of the agents involved in UTIs may help clinicians to choose appropriate antimicrobial treatments. The present study determined the bacteriological profile and antimicrobial susceptibility patterns of urine culture isolates among patients in Ndjamena General Hospital of National Reference, Chad. In this study, 216 (32.7%) on 660 urine samples met the criteria for urinary tract infection. This data contrasts with those presented by other surveillance studies. Irenge et al. [8] among 2,724 urine samples processed in a tertiary care hospital in south Kivu Province (Democratic republic of Congo) found a rate of 23.6%. Beyene and Tsegaye [9] obtained a bacteriuria of 9.2% from 228 cultured urine specimens in Jimma University Specialized Hospital in Southwest Ethiopia whereas Villar et al. [10] recorded a result of 25.5% from 3.105 urine samples collected from male outpatients in Argentina. The data reported in this study showed a high bacteriuria in inpatients compared to outpatients. This result is in line with that of Gupta et al. [11] and might reflect infections acquired during hospitalization. E. coli is the major etiological agent involved in urinary tract infections accounting for up to 90% of cases [5]. E. coli was the most common bacteria isolated from urine samples in both inpatients and outpatients of both sexes and this finding is in agreement with other studies [1,12-14]. In contrary to another study where the second reported isolate was Proteus mirabilis [15], in this study, it was K. pneumonia followed by E. cloacae which is in agreement with the findings of Ghorbani et al. [1].

 

Resistance to antimicrobial agents has been noted since the first use of these agents and is an increasing worldwide problem [16]. The Infectious Diseases Society of America guidelines suggest that 10-20% resistance warrants a change in the recommended antibiotic used as the first line therapy [17]. In the present study, only imipeneme (94.9%) displayed satisfactory activity against pathogens. High antibiotic-resistance rate was observed with other antimicrobial drugs. Resistance of isolates to betalactamines was mainly due to production of ESBLs. It has been found that the increasing frequency of ESBL phenotypes is an emerging problem due to the enormous potential for multidrug resistance from strains that produce these enzymes [18]. Acetylation of aminoglycosides by acetyltransferases is one of the major mechanisms of acquired resistance to these compounds [19, 20]. The 3-N-aminoglycoside acetyltransferases (AAC(3) enzymes) and the 6’-N- aminoglycoside acetyltransferases (AAC(6’) enzymes) were found to be among the modifying enzymes most commonly encountered in clinical isolates [19, 21]. The AAC(3)-I enzymes confer resistance to gentamycin, sisomicin and astromicin and are widespread among Enterobacteriaceae [21, 22]. These findings were also observed in the current study. The involved mechanisms of resistance to quinolones were alterations in the targets of quinolones, decreased accumulation due to impermeability of the membrane and/or an over expression of efflux pump systems and an association of many of these. This result agrees in some respect with other studies [23, 24].

 

The decreased susceptibility rates found for many agents in the current study is worrisome, since some of them are currently prescribed in Ndjamena as first line agents for treating hospital or community acquired infections such as UTIs. The current data may reflect the extensive use of prescribed agents. This over use may select for multidrug resistant strains, harboring the potential to disseminate within a specific region.

 

 

Conclusion Up    Down

E. coli remains the most common bacterial uropathogen responsible for UTIs in Ndjamena. This study confirms the presence of antibiotic-resistant uropathogens in this study area. As drug resistance is an evolving process, routine surveillance and monitoring studies should be conducted to provide physicians with knowledge about the most effective empirical treatment of UTIs.

What is known about this topic

  • E. coli is the most important cause of urinary tract infections;
  • Antibiotics resistance of uropathogens varies from countries and regions;
  • Infections caused by resistant microorganisms often fail to respond to empiric treatment.

What this study adds

  • E. coli is the most common bacterial uropathogen responsible for UTIs in Ndjamena;
  • Imipenem is the appropriate antibiotic for treating UTIs in Ndjamena;
  • Antibiotics resistance of the uropathogen responsible for UTIs occurs mainly through production of extended spectrum betalactamases (ESBLs).

 

 

Competing interests Up    Down

The authors declare no competing interests.

 

 

Authors’ contributions Up    Down

Michel Kengne: conceived, designed, financed the study and produced the first draft of this manuscript. Amon Todjimbaide Dounia performed the sample collection, the laboratory assays and the data analysis and interpretation. Julius Mbekem Nwobegahay corrected the research proposal before the study and did a thorough review of the manuscript. All authors have read and agreed to the final manuscript.

 

 

Acknowledgments Up    Down

Special thanks are due to the participants who provided the specimen and to the Director of the Ndjamena General Hospital of National Reference in Chad who granted the research authorization for this study.

 

 

Tables Up    Down

Table 1: distribution of uropathogens in patients

Table 2: percentage of resistance of isolates to antibiotics

Table 3: resistance mechanism/phenotype of resistant isolates

 

 

References Up    Down

  1. Ghorbani A, Ehsanpour A, Roshanzamir N, Omidvar B. Alterations in antibiotic susceptibility of urinary tract infection pathogens. J Nephropathol. 2012 Apr;1(1):43-8. PubMed | Google Scholar

  2. Ronald AR, Nicolle LE, Stamm E et al. Urinary tract infection in adults: research priorities and strategies. Int J Antimicrob Agents. 2001 Apr;17(4):343-8. PubMed | Google Scholar

  3. Barisić Z, Babić-Erceg A, Borzić E, Zoranić V, Kaliterna V, Carev M. Urinary tract infections in South Croatia: etiology and antimicrobial resistance. Int J Antimicrob Agents. 2003 Oct;22 Suppl 2:61-4. PubMed | Google Scholar

  4. Jinnah F, Islam MS, Rumi MAK, Morshed MG, Huq F. Drug sensitivity pattern of E. Coli causing urinary tract infection in diabetic and non-diabetic patients J Int Med Res. 1996 May-Jun;24(3):296-301. PubMed | Google Scholar

  5. Ronald A. The etiology of urinary tract infection: traditional and emerging pathogens. Am J Med. 2002 Jul 8;113 Suppl 1A:14S-19S. PubMed | Google Scholar

  6. Lau SM, Peng MY, Chang FY. Resistance rates to commonly used antimicrobials among pathogens of both bacteremic and non bacteremic community-acquired urinary tract infection. J Microbiol Immunol Infect. 2004 Jun; 37(3):185-91. PubMed | Google Scholar

  7. Cuba GT, Pignatari AC, Patekosky KS, Luchesi LJ, Kiffer CR. Pharmacodynamic profiling of commonly prescribed antimicrobial drugs against Escherichia coli isolates from urinary tract. Braz J Infect Dis. 2014 Sept-Oct;18(5):512-7. PubMed | Google Scholar

  8. Irenge LM, Kabego L, Vandenberg O, Chirimwami RB, Gala JL. Antimicrobial resistance in urinary isolates from inpatients and outpatients at a tertiary care hospital in South-Kivu Province (Democratic Republic of Congo). BMC Res Notes. 2014 Jun 18;7:374. PubMed | Google Scholar

  9. Beyene G, Tsegaye W. Bacterial uropathogens in urinary tract infection and antibiotic susceptibility pattern in Jimma University Specialized Hospital, Southwest Ethiopia. Ethiop J Health Sci. 2011 Jul;21(2):141-6. PubMed | Google Scholar

  10. Villar HE, Jugo MB, Macan A, Visser M, Hidalgo M, Maccallini GC. Frequency and antibiotic susceptibility patterns of urinary pathogens in male outpatients in Argentina. J Infect Dev Ctries. 2014 Jun 11;8(6):699-704. PubMed | Google Scholar

  11. Gupta K, Sahm DF, Mayfield D, Stamm WE. Antimicrobial resistance among uropathogens that cause community–acquired urinary tract infections in women: a nationwide analysis. Clin Infect Dis. 2001 Jul 1;33(1):89-94. Epub 2001 Jun 5. PubMed | Google Scholar

  12. Farajnia S, Alikhani MY, Ghotaslou R, Naghili B, Nakhlband A. Causative agents and antimicrobial susceptibilities of urinary tract infections in the northwest of Iran. Int J Infect Dis. 2009 Mar;13(2):140-4. Epub 2008 Aug 13. PubMed | Google Scholar

  13. Tessema B, Kassu A, Mulu A, Yismaw G. Pridominant isolates of urinary tract pathogens and their antimicrobial susceptiblity patterns in Gondar University Teaching Hospital, nothwest Ethiopia. Ethiop Med J. 2007 Jan;45(1):61-7. PubMed | Google Scholar

  14. Raka L, Mulliqi-Osmani G, Berisha L, Begolli L, Omeragiq S, Parsons L, Salfinger M, Jaka A, Kurti A, Jakupi X. Etiology and susceptibility of urinary tract isolates in Kosova. Int J Antimicrob Agents. 2004 Mar;23 Suppl 1:S2-5. PubMed | Google Scholar

  15. Andrade SS, Sader HS, Jones RN, Pereira AS, Pignatari AC, Gales AC. Increased resistance to first-line agents among bacterial pathogens isolated from urinary tract infections in Latin America: time for local guidelines?. Mem Inst Oswaldo Cruz. 2006 Nov;101(7):741-8. PubMed | Google Scholar

  16. Sefton AM. The impact of resistance on the management of urinary tract infections. Int J Antimicrob Agents. 2000 Dec;16(4):489-91. PubMed | Google Scholar

  17. Warren JW, Abrutyn E, Hebel JR, Johnson JR, Schaeffer AJ, Stamm WE. Guidelines for antimicrobial treatment of uncomplicated acute bacterial cystitis and acute pyelonephritis in women. Clin Infect Dis. 1999 Oct;29(4):745-58. PubMed | Google Scholar

  18. McCraig LF, Besser RE, Hughes JM. Antimicrobial drug prescription in ambulatory care settings, United States 1992-2000. Emerg Infect Dis. 2003 Apr;9(4):432-37. PubMed | Google Scholar

  19. Davies J, Wright GD. Bacterial resistance to aminoglycoside antibiotics. Trends Microbiol. 1997 Jun;5(6):234-40. PubMed | Google Scholar

  20. Mingeot-Leclercq MP, Glupczynski Y, Tulkens PM. Aminoglycosides: activity and resistance. Antimicrob Agents Chemother. 1999 Apr;43(4):727-37. PubMed | Google Scholar

  21. Miller GH, Sabatelli FJ, Hare RS, Glupczynski Y, Mackey P, Shlaes D, Shimizu K, Shaw KJ, the aminoglycoside resistance study groups. The most frequent aminoglycoside resistance mechanisms changes with time and geographic area: a reflection of aminoglycoside usage patterns? Clin Infect Dis. 1997 Jan;24(1):S46-S62. PubMed | Google Scholar

  22. Javier Terán F, Alvarez M, Suárez JE, Mendoza MC. Characterization of two aminoglycoside-(3)-N-acetyltransferase genes and assay as epidemiological probes. J Antimicrob Chemother. 1991 Sep;28(3):333-46. PubMed | Google Scholar

  23. Ruiz J. Mechanisms of resistance to quinolones: target alterations, decreased accumulation and DNA gyrase protection. J Antimicrob Chemother. 2003 May;51(5):1109-17. PubMed | Google Scholar

  24. Bălăşoiu M, Bălăşoiu AT, Mănescu R, Avramescu C, Ionete O. Pseudomonas aeruginosa resistance phenotypes and phenotypic highlighting methods. Curr Health Sci J. 2014 Apr-Jun;40(2):85-92. Epub 2014 Mar 29. PubMed | Google Scholar