The hen’s egg is more proteinase food supplement and rich in nutrients. Hens are used as food purpose and hatching of chicks too. Contrary to this whole egg provides a brilliant environment for the growth of bacterial microflora, plus pathogenic bacteria (Stepien-Pysniak 2010). In present study, a total of 300 egg samples, i.e. 150 egg shells and 150 egg interiors were collected and evaluated for the bacterial growth on nutrient agar and lactose broth, respectively (Fig. 1). In general, there was significant difference in positive vs. negative samples being highest prevalence (82%) of pathogenic bacteria on egg shells and very low bacterial prevalence in egg interior (10%, n = 15). On the other hand, approximately 90% of the egg interior samples (n = 135) did not show any bacterial growth. The egg albumen may possesses some antimicrobial defense mechanisms, such as its organization in the aluminous sac and the viscosity of its protein (Al-Jaff 2005). The penetrability of some pathogens through the shell, light brown fertile and brown infertile eggs was subjected to microbiological analyses (Al-Jaff 2005). Among all, four different types of bacterial isolates i.e., Enterobacter spp. and Salmonella enterica based on their morpho-microscopic and molecular characteristics were identified. Microbiologist also isolated Salmonella bacteria and many other microorganisms from the shell of hen’s eggs (Stepien-Pysniak 2010).
In a pilot study conducted in Grenada with 160 table eggs, majority of the bacterial isolates belong to Enterobacteriaceae group (Sabarinath et al. 2009). The results of research showed that incidence of Salmonella spp. in chicken egg from the general shop in Khulna city is higher than the normal ratio (Hasan et al. 2009). More over incidence of Salmonella spp. in broken eggs is relatively very high than the fresh eggs (Hasan et al. 2009). The shell probably receives microorganisms when passing through the cloaca and during the time until the egg is used (Al-Jaff 2005). The fact that eggs can be contaminated or infected through the shell or transovarially, makes them a probable cause of pathogens contributing in the etiology of foodborne illnesses in humans (Stepien-Pysniak 2010). It has been observed in both the US and the UK union in common conduction of infection caused by S. enteritidis in human (Zou et al. 2012). These species possessed great resistance power against the action of antibiotics and retain their growth even in the presence of drugs. These microorganisms develop resistance to antibiotics under the mechanisms such as choice, change, phage transduction, and conveyance while microbial resistance can either be intrinsic in the organism or developed through the environment (Chinedum 2005).
In this study, the antibiotic sensitivity of the four isolates was tested against 06 antimicrobial agents of β-lactam and cephalosporin antibiotics. All the bacterial isolates were susceptible to β-lactam group of antibiotics except Enterobacter sp. ES1, which showed complete resistance towards Amoxicillin. Similarly, S. enterica ES2 also showed complete resistance towards Amoxicillin. Clinically, E. cloacae and E. hormaechei are the maximum collective species in the genus Enterobacter. For 10 years, the two species have been increasingly considered as causative agent for the infections in hospitalized patients. They are characterized by resistance to broad-spectrum β-lactam agents by producing extended-spectrum β-lactamase and inducible chromosome-encoded cephalosporinase (Davin-Regli et al. 1997). Resistance of Enterobacter species to extended-spectrum cephalosporin is identified to be interceded by hyper manufacture of chromosomal AmpC β-lactamases (Davin-Regli et al. 1997). S. enterica ES5 did not show significant difference in inhibition zones for β-lactam group of antibiotics, however, Enterobacter sp. ES1 and S. enterica ES4 displayed significant differences among the treatments. Contrarily, all the four isolates showed complete resistance to cephalothin and cefuroxime sodium, whereas there was significant sensitivity of ceftriaxone against all the four bacterial isolate (Learn-Han et al. 2009). Learn- Han et al. (2009) also reported the order of resistant profile of S. enterica against ceftriaxone, cefuroxime, ampicillin, cephalothin and cefotaxime to be 14%, 12%, 10%, 9% and 7%, respectively (Learn-Han et al. 2009). In present study, the antimicrobial activity of four fluoroquinolone antibiotics, i.e. enoxacin, ciprofloxacin, sparfloxacin and moxifloxacin were examined. Although, all the isolates were sensitive to enoxacin, ciprofloxacin and sparfloxacin antibiotics, fluoroquinolones are often the treatment of choice in the cases of life-threatening Salmonellosis due to multidrug-resistant strains (Giraud et al. 2000).
Fluoroquinolones and the third-generation cephalosporin’s are recommended for use in areas where there are resistant organisms (Chiu et al. 2002). However, the S. enterica isolates, i.e. S. enterica ES4 and S. enterica ES5, displayed complete resistance against moxifloxacin antibiotic. While fluoroquinolone used animals that is failed to produce any resistance (Chiu et al. 2002). However, Enterobacter species showed significant sensitivity to moxifloxacin, also signified that among the tested fuoroquinolones, sparfloxacin was rated as most significant treatment against all the bacterial isolates. Fluoroquinolone is used for treatment of invasive gastrointestinal infections across the world (Aarestrup et al. 2003). Moreover, the bacterial isolates Enterobacter sp. ES1, S. enterica ES2, S. enterica ES4 and S. enterica ES5 were tested for antimicrobial sensitivity against one sulfonamide (sulphamethoxazole), two aminoglycoside (amikacin and gentamicin) and two macrolide (erythromycin and azomax) antibiotics. In general, all the four bacterial isolates were sensitive to amikacin and gentamicin antibiotics, whereas the Enterobacter sp. ES1 and S. enterica ES2 also showed significant and highest sensitivity to sulphamethoxazole. Contrarily, both the S. enterica isolates, i.e. ES4 and ES5, were completely resistant to sulphamethoxazole. S. enterica serotype typhimurium is frequent agents of bacterial enteritis that shows great resistance against multiple drugs, especially sulfonamides (Tosini et al. 1998). However, all the four bacterial isolates were resistant erythromycin, while only Enterobacter sp. ES1 showed moderate sensitivity towards Azomax, the macrolide antibiotics.
Antibiotics showed a great effective result against the gram’s positive bacteria, on other hand gram’s negative bacteria posed great resistance against these drugs (Poole 2005). While, the antibiotic sensitivity of the four isolates against three antimicrobial agents, i.e. vancomycin, urixin and fosfomycin, the representatives of glycopeptide, pipemidic acid and phosphonic antibiotics, respectively. All isolates were significantly sensitive to urixin (pipemidic acid) antibiotic, while the isolates were resistant to the glycopeptide, vancomycin. The increase of resistance to vancomycin new classes of antibiotics, revealed active against MRSA, such as linezolid and daptomycin, is irritating (Ge et al. 2008). In addition, only Enterobacter sp. ES1 isolates was found to be resistant to Fosfomycin, whereas, the other three isolates displayed significant sensitivity to fosfomycin (the phosphonic antibiotic). Clinical effectiveness of an old antibiotic, fosfomycin, high effective activity against multidrug-resistant gram-negative bacilli belonging to the family Enterobacteriaceae (Wachino et al. 2010). Unfortunately, resistance develops rapidly when fosfomycin is used as monotherapy, therefore, combinations with other antimicrobials are preferred in clinical practice for the treatment of serious infections (Souli et al. 2011).