Resistance of Escherichia coli and Klebsiella pneumoniae isolated from different Sources to β-lactam Antibiotics

 

Hisham A. Abbas1*, Ashraf A. Kadry1, Ghada H. Shaker1, Reham M. Goda2

1Department of Microbiology and Immunology-Faculty of Pharmacy-Zagazig University- Zagazig- Egypt

2Department of Microbiology and Biotechnology, Faculty of Pharmacy-Delta University for Science and Technology-Gamasa, Mansoura, Egypt

*Corresponding Author E-mail: hishamabbas2008@gmail.com

 

ABSTRACT:

Escherichia coli and Klebsiella pneumoniae are important human pathogens that cause many infectious diseases. β-lactam antibiotics are commonly used in the treatment of these infections. However, resistance to such antibiotics complicates the treatment. Mechanisms of resistance to β-lactams include production of β-lactamases, efflux pumps, change in drug targets and outer membrane impermeability. This study was performed to investigate the resistance of Klebsiella pneumoniae and Escherichia coli to β-lactam antibiotics. The study was carried out from May 2014 to May 2015.  Five hundred clinical isolates were collected from patients in Belquas Hospital and Mansoura University Hospitals. Three hundred isolates were identified as Klebsiella pneumoniae and Escherichia coli (one hundred and fifty isolates each). Klebsiella pneumoniae and Escherichia coli isolates showed high resistance to cefoperazone and ceftriaxone, intermediate resistance to cefoxitin, cefotaxime, ceftazidime and amoxicillin-clavulanic acid and low resistance to imipenem and meropenem. Klebsiella pneumoniae showed more resistance than Escherichia coli. Resistance of Klebsiella pneumoniae was higher to cefoperazone, ceftriaxone, ceftazidime, imipenem and meropenem. However, Escherichia coli was more resistant to cefotaxime and cefoxitin. The resistance to amoxicillin-clavulinic acid was more or less similar in both bacteria. In conclusion, the resistance of Klebsiella pneumoniae and Escherichia coli isolates to B-lactams was high and this needs a strict policy for antibiotic dispensing to reduce the emergence of resistance.

 

KEYWORDS: β-lactams, resistance, Klebsiella pneumoniae, Escherichia coli

 

 


INTRODUCTION:

Resistance of pathogenic organisms to antibiotics has become a worldwide problem with serious consequences on the treatment of infectious diseases. The excessive use and misuse of antibiotics in human medicine, agriculture and veterinary medicine are major contributing factors to antibiotic resistance. The high rate of emergence of antibiotic resistance in bacteria causing community acquired infections or nosocomial infections is a dangerous alarm particularly the multidrug resistant pathogens such as Klebsiella pneumoniae and Escherichia coli 1.

 

Beta-lactam antibiotics are commonly used for the treatment of bacterial infections caused by Klebsiella pneumoniae and Escherichia coli. However, the continuous use of β-lactams has resulted in emergence of resistance2,3. Bacterial resistance to beta-lactam antibiotics is achieved either by the production of β-lactam hydrolyzing β-lactamase enzymes, change of drug targets or the active expulsion of β-lactam molecules from Gram-negative cells by means of efflux pumps 4. It is noteworthy that β-lactamases is the single most prevalent mechanism responsible for resistance to β-lactams among clinical isolates of Enterobacteriaceae5. This study aimed to investigate the resistance of Klebsiella pneumoniae and Escherichia coli isolates to β-lactam antibiotics.

 

MATERIALS AND METHODS:

Bacterial Strains:

A total of five hundreds isolates were collected over the period from May 2014 to May 2015 from patients in Belquas Hospital and Mansoura University Hospitals. All isolates were collected and handled in accordance with accepted laboratory procedures. All regulations concerning the collection of specimens had been thoroughly followed for proper sampling techniques6. The clinical samples were obtained from blood, urine, sputum, urinary catheters, end tracheal tube aspirate (ETA), end tracheal tube part (ETTP), T-tube part (TTP) and T-tube aspirate (TTA) One hundred and fifty of isolates were identified as Escherichia coli and another 150 isolates were identified as Klebsiella pneumoniae and all isolates were subjected to further biochemical identification according to Koneman et al.6

 

Antimicrobial susceptibility testing:

E. coli and K. pneumoniae isolates were tested for their susceptibility to different antimicrobial agents by the disk diffusion method according to CLSI 7. The antibiotic disks used were imipenem (IPM, 10mg), meropenem (MEM, 10mg), cefotaxime (CTX, 30mg), ceftriaxone (CRO, 30mg), cefoxitin (FOX, 30mg), cefoperazone (CFP, 75mg), ceftazidime (CAZ, 30mg), amoxicillin-clavulanic acid (AMC, 30 mg). Four separate colonies of each isolate were transferred with sterile wire loop to a tube containing 5 ml of Mueller Hinton broth (MHB). The broth was incubated at 37oC to achieve a turbidity approximately equivalent to 0.5 McFarland standards. The broth cultures were further diluted 1: 200 in broth to obtain inoculums density ranged between 105 and 106 cells/ ml. A sterile cotton swab was dipped into the bacterial suspension (within 15 minutes of adjusting the density of inoculums) and the excess liquid was removed by rotating the swab several time against the inside wall of the tube above the fluid level. The surface of a dried Mueller Hinton agar plate was streaked with inoculating the swab in different directions. The inoculated plates were left on a flat level surface undisturbed for 3-5 minutes; the antibiotic disks were placed on the inoculated plates and lightly pressed into the agar with the forceps. The plates were incubated inverted at 37oC for 18h. The plates were examined and the diameters of the complete inhibition zones were measured in mm and interpreted according to CLSI 7.

 

RESULTS

Isolation and identification of isolates:

Out of five hundred different clinical isolates, three hundred were identified as Klebsiella pneumoniae and Escherichia coli isolates. One hundred and fifty isolates were identified as Escherichia coli and another 150 isolates were identified as Klebsiella pneumoniae. K. pneumoniae and E. coli isolates were presumptively identified as Gram negative rods with lactose fermenting colonies on MacConkey agar. Further Confirmation was based on their biochemical characters as in table 1.


 

Table 1. Identification of E. coli and K. pneumoniae isolates.

Test

Indole test

Methyl red test

Voges-proskauer test

Citrate utilization test

Growth on TSI agar

Motility

Urease test

E. coli

+

+

-

-

A/A+CO2

+

-

K. pneumoniae

-

-

+

+

A/A+CO2

-

+

TSI: Triple sugar iron A: Acidic, K: Alkaline

 


Susceptibility patterns of K. pneumoniae and E. coli isolates to different antimicrobial agents by the disk diffusion method.

To investigate the resistance of Klebsiella pneumoniae and Escherichia coli isolates to β-lactams, the disk diffusion method was used and the results are presented in table 2-4. Fifteen isolates (10%) were resistant to each of imipenem and meropenem, while 50 (33.33%) isolates were resistant to cefotaxime and 58 (38.67%) isolates were resistant to amoxicillin-clavulanic acid. Moreover, 63 (42%) isolates were resistant to cefoxitin, 74 (49.33%) isolates to ceftazidime, while 126 (84%) and 128 (85.33%) isolates were resistant to cefoperazone and ceftriaxone, respectively. Concerning the resistance of E. coli, 2 (1.33%) isolates were resistant to each of imipenem and meropenem. However, 59 (39.33%) isolates were resistant to amoxicillin-clavulanic acid, 64 (42.67%) and 66 (44%) isolates were resistant to cefotaxime and ceftazidime, respectively. Furthermore, 87 (58%) isolates were resistant to cefoxitin, 97(64.67%) isolates were resistant to ceftriaxone and 106 (70.67%) isolates were resistant to cefoperazone.

 

Table 2. Antibiotic susceptibility of K. pneumoniae and E. coli isolates by the disk diffusion method

Antibiotics

Number (%) of resistant  isolates

E. coli

K. pneumoniae

Cefoperazone

106 (70.67)

126 (84)

Ceftriaxone

97 (64.67)

128 (85.33)

Cefotaxime

64 (42.67)

50 (33.33)

Amoxicillin-clavulinic acid

59 (39.33)

58 (38.67)

Cefoxitin

87 (58)

63 (42)

Ceftazidime

66 (44)

74 (49.33)

Imipenem

2 (1.33)

15 (10)

Meropenem

2 (1.33)

15 (10)

 

DISCUSSION:

The emergence of resistance to β-lactamas has drawn attention to the need to newer drugs to allow more specific therapy. Therefore, the detection of such resistance can lead to successful infection control, involving antimicrobial stewardship and public health interventions aimed at controlling the emergence of such life-threatening beta-lactams resistant bacteria 8. Antibiotic susceptibility test was conducted for Klebsiella pneumoniae isolates. High resistance rates were observed with cefoperazone (84%) were resistant to and ceftriaxone (85.33%). Intermediate resistance rates were found with cefotaxime (33.33), amoxicillin-clavulanic acid (38.67%), cefoxitin (42%) and ceftazidime (49.33%). These results were in agreement with Du et al.9 on the other hand, low resistance were reported with imipenem and meropenem (10% each). These rates were higher than that reported by Du et al.9 who found that only 3.3% and 2.6% of isolates were resistant to imipenem and meropenem, respectively. Escherichia coli isolates showed high resistance to cefoperazone (70.67%) and ceftriaxone (64.67%). Intermediate resistance was found with cefoxitin (58%), cefotaxime (42.67%), ceftazidime (44%) and amoxicillin-clavulanic acid (39.33%), while low resistance was observed with imipenem (1.33%) and meropenem (1.33%). These results were in accordance with those of. Our finding is similar to the observation of Khadgi et al.10 Comparing the resistance rates of Klebsiella pneumoniae and Escherichia coli isolates, Klebsiella pneumoniae was generally more resistant than Escherichia coli. Klebsiella pneumoniae showed higher resistance to cefoperazone, ceftriaxone, ceftazidime, imipenem and meropenem. However, Escherichia coli showed higher resistance to cefotaxime and cefoxitin. The resistance to amoxicillin-clavulinic acid was more or less similar in both bacteria.

 

CONCLUSION:

Klebsiella pneumoniae and Escherichia coli isolates showed significant resistance to most of the commonly prescribed β-lactam antibiotics. This high resistance necessitates a strict antibiotic policy to reduce the emergence of resistance. On the other hand, resistance to carbapenems was found to be low and these drugs would be the appropriate empiric therapy for serious or life threatening systemic infections caused by Klebsiella pneumoniae and Escherichia coli.

 

CONFLICT OF INTEREST:

There is no conflict of interest

 

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Received on 13.10.2016             Modified on 06.11.2016

Accepted on 15.02.2017           © RJPT All right reserved

Research J. Pharm. and Tech. 2017; 10(2): 589-591.

DOI: 10.5958/0974-360X.2017.00116.0