Multidrug Resistance Pattern of Enterobacter Spp. Isolated from Acute Respiratory Tract Infected Camels (Camelus dromedarius)

| The genus Enterobacter is a gram negative commensal coliform member of Enterobacteriaceae. In immunocompromised animals Enterobacter become opportunistic pathogen and severely affects therapeutic management of infections by evading proper effects of antibiotics. Thus the present study was designed to determine resistance pattern of Enterobacter obtained from acute respiratory tract infected camels (Camelus dromedarius). Total 16 Enterobacter spp. isolates were obtained from 46 deep nasal discharge samples of acute respiratory tract infected camels and preliminarily confirmed on the basis of IMViC pattern, hemolysis and sugar fermentation pattern. Confirmed isolates were screened for susceptibility against 25 antibiotics of various groups. All isolates were showed multidrug resistance pattern and 100% isolates were resistant to ampicillin, bacitracin, erythromycin, clindamycin, rifampicin, vancomycin and oxacillin. While all isolates were sensitive to gentamicin and imepenem and in decreasing order isolates were showing variable percentage of sensitivity for cefepime and ciprofloxacin (93.75%), norfloxacin and cefotaxime (87.50%), ceftazidime and co-trimoxazole (81.25%), colistin (68.75%), chloramphenicol (62.50%), kanamycin and trimethoprim (56.25%), tetracycline (31.25%) and cephalothin (25%) isolates were sensitive.


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tracts infections (Wilberger et al., 2012).Thus it was observed that Enterobacter commonly associated with respiratory, gastrointestinal and urinary tract infections in addition to wound, bloodstream, and central nervous system infections (Bordeanu et al., 2012).
The physical examination of Enterobacter respiratory tract infections may include high fever, tachycardia, hypoxemia and cyanosis.Infected animal with pulmonary consolidation may present with crackling sounds, dullness to percussion, tubular breath sounds and egophony.Pleural effusion may manifest as dullness to percussion and decreased breath sounds (Edward and Ewing, 1972;Gohary et al., 2012).Since during the last decade Enterobacter has emerged as an important hospital pathogen responsible for nosocomial respiratory tract infections with exhibiting high resistance to broad-spectrum antibiotics and the emergence of extended-spectrum cephalosporin-resistant strains has been also documented (Thiolas et al., 2005).In addition to diseases causing, genus Enterobacter is also capable to acquire antibiotic resistance in short time with various mechanism such as Beta-lactamase & Extended-Spectrum Beta-lactamase (ESBL) production, multidrug efflux system, low outer membrane permeability, mutations in chromosomal genes and additional acquired resistance genes via plasmids, transposons and phage makes this organism highly resistant (Harbottle et al., 2006).Though multidrug resistance pattern of Enterobacter among human patients explored well but in animals especially camels it has not studied very much.Thus the present study was carried out to characterize genus Enterobacter from respiratory tract infection in camels on the basis of their biochemical properties and to determine multidrug resistance pattern of organism for prevention of further morbidity and mortality of animals because of resistant opportunistic pathogens.

ISolatIon and IdentIfIcatIon
A total of 46 samples of deep nasal discharge from acute respiratory tract infected camels were collected aseptically with sterile absorbent swabs soaked in nutrient broth.All samples has been collected from clinical complex of college of veterinary and animal science, Bikaner (Rajasthan) India on the basis of clinical symptoms of acute respiratory tract infection without discrimination of age, sex and breed of cam-els.The samples were inoculated on nutrient agar plates and then processed for isolation and identification of Enterobacter spp.(Cowan and Steel 1974;Quinn et al., 1994).Out of the 46 samples 16 suspected isolates were proceeded on the basis of phenotypic and biochemical properties such as cultural characteristics, motility, lactose fermentation, IMViC pattern, H 2 S production in TSI agar, lysine decarboxylase and urease activity.

antIbIotIc SenSItIvItY teSt
To determine the antibiogram of the isolates against various 25 antibiotics (Table 1) the method of Bauer et al. ( 1966) was followed.The isolates were inoculated in sterile 5 ml nutrient broth tubes and incubated for 18 hour at 37 o C. The opacity was adjusted to 0.5 McFarland opacity standards (Quinn et al., 1994) and inoculums were well spread over the agar surface with the help of sterilized swab.Plates were allowed to dry for 10 minute at 37 o C and then antibiotic discs (Hi Media, Mumbai) were carefully placed on the surface with enough space around each disc for diffusion of the antibiotic.Plates were incubated for 24 hour at 37 o C and the diameter of zone of inhibition of growth around each disc was measured in millimeters.After inhibition zone measurement, result interpretation was made with standard chart provided by disc manufacturer (Hi Media, Mumbai).

RESULTS
In the present investigation 16 Enterobacter spp.were isolated from 46 nasal samples from acute respiratory tract infected camels on the basis of their phenotypic and biochemical properties.All the isolates showed pink lactose fermenting, non-metallic sheen, mucoid colonies on respective culture media with typical IMViC pattern (--+ +) and not produced H 2 S gas in Triple Sugar Iron (TSI) agar.Typically all isolates were motile, urease positive and negative for lysine decarboxylation.In antibiogram study, all isolates were 100% sensitive to gentamicin and imipenem while completely resistant to ampicillin, bacitracin, erythromycin, clindamycin, rifampicin, vancomycin and oxacillin.All Enterobacters showed multidrug resistance pattern with minimum resistance to fifteen antibiotics.

DISCUSSION
In the present study, Enterobacter spp.showed typical biochemical and cultural phenotypic characteristic as described in literature (Edward and Ewing, 1972;Cowan and Steel, 1975 Osterblad et al., 1999) and in the study of Magnet et al. (2013), Enterobacter spp.were resistant to most of antibiotics, but were moderately sensitive (50%) to ciprofloxacin, tetracycline and doxycycline.
Observations in present study had accordance with the Al-Juboori et al. ( 2013), who revealed that the Enterobacter isolates from clinical and subclinical mastitis from camel milk showed moderate sensitivity to carbenicillin, streptomycin, sulphamethoxazole and gentamicin while less sensitive or even resistive towards ampicillin, colistin, penicillin G and tetracycline.Greenup and Blazevic, (1971) found slight variations that all the 28 strains of Enterobacter were sensitive towards gentamicin, chloramphenicol and nalidixic acid followed by sulfisoxazole, kanamycin, tetracycline, streptomycin and all were resistant to ampicillin.The Enterobacter was resistant to ampicillin (81.3%), chloramphenicol (75.0%), ciprofloxacin (6.3%), enrofloxacin (18.8%), neomycin (37.5%), norfloxacin (25.0%), streptomycin (56.3%) and tetracycline (75.0%) in the study of antimicrobial susceptibility of Enterobacter aerogenes from free-range chickens (Ojo et al., 2012)  McEwen and Fedorka-Cray ( 2002) has also concluded that excessive use of antibiotics induces the selection of resistant strains by producing hydrolytic enzymes and decreasing the active drug concentration via the alteration of permeability in outer membranes and enhances persistence and dissemination of antibiotic resistance not only in hospitals but also in food chains and ecosystems.In the presence of above facts, present study may conclude that antibiotic resistance not only govern by various inherited and acquired mechanisms but also by indiscriminate use of antibiotic thus the present study suggest prudent and wise use of antibiotics and further molecular studies to find exact mechanism of antibiotic resistance along with genetic characterization of Enterobacter strains to curb mortality and morbidity due to resistant infections.

Advances in Animal and Veterinary Sciences February 2015 | Volume 3 | Issue 2 | Page 130Table 1 :
The studied isolates were sensitive with following decreasing percentage such as cefepime & ciprofloxacin (93.75%), norfloxacin & cefotaxime (87.50%), ceftazidime & co-trimoxazole (81.25%) and 56.25% Antibiogram of Enterobacter spp.obtained from acute respiratory tract infected camels Enterobacter strains in this investigation.Wilberger et al. (2012) also found similar positive correlation of increased use of antibiotic and their resistance for enrofloxacin and gentamicin in the USA during study of antibiotic resistance among Enterobacter spp.isolated from infection in animals.