doi:10.5455/vetworld.2013.91-94 Isolation, histopathology and antibiogram of Escherichia coli from pigeons (Columba livia)

Aim: To know the prevalence of antibiotic resistant Escherichia coli among dead and/or diarrhoic pigeons in and around greater Guwahati. Materials and Methods: Samples were cultured from dead and/or diarrhoic pigeons and identification was done by standard methods. The sensitivity of the isolated E.coli strains to 15 antibiotics of human and veterinary use was also determined. Organs from those dead birds from which E.coli were recovered were processed according to the routine procedure for histopathological studies. Results: Out of 150 pigeons subjected to microbiological investigation, 91(60.67 %) samples were found positive for E. coli. The most frequently occurring serotypes were O157 (9.89%), followed by O68, O121 (7.69%), O9, O75, O131 (5.49%), O2, O13, O22 (3.30%). Antibiogram investigation of the isolates revealed that 91isolates (100%) exhibited resistance against Ampicillin followed by Nitro-furantoin (73.62%), Tetracycline (65.93 %), Oxytetracycline (62.63 %) and Streptomycin (61.54). Gross changes of some birds showed fibrinous pericarditis and perihepatitis and coligranuloma in different organs like liver and serosal surface of intestine. Microscopically, severe congestion and haemorrhages in different organs such as liver, kidney, lung and intestine. In some cases thick layer of fibrinous exudates with large number of heterophills over the surface of liver and heart with early degenerative changes as well as focal necrosis. Conclusion: The result of this study suggests that antimicrobial-resistant pathogenic E.coli is present in pigeons in and around greater Guwahati. Surveillance programs may be introduced to monitor antimicrobial resistance of pathogenic E.coli in pigeons in and around greater guwahati.


Introduction
two or more classes of antibiotics is become common in veterinary medicine [4].Pigeons had been associated with human society Therefore, the present study was undertaken to both as a source of food and as cage birds from a long identify the major serotypes of E. coli prevailing in time.Out of 8600 nos. of known species of birds, 289 pigeon, their antimicrobial susceptibility and histospecies are of pigeon.They are reared scientifically in pathological studies in and around greater Guwahati.Belgium and England, as the people used to exhibit the flock in racing competition.

Pigeons come into close contact with humans and
One hundred and fifty samples were collected animals, and may contribute to the spread of infectious from organs of fresh carcasses and/or diarrheic pigeons agents.Workers from different countries have reported in and around greater Guwahati and subjected to variable incidence of bacterial diseases in pigeons.
isolation of E.coli as per standard method [5].The Among the bacterial agents, E. coli, Streptococci and isolates were identified on the basis of their cultural, Salmonella infections are common in pigeons [1].E. morphological and biochemical characteristics [6]. coli strains causing human diarrhea which may be able The isolates were referred at National Salmonella and to survive in pigeon feces, may create potential human Escherichia Centre, Central Research Institute, Kasauli exposure.Use of antimicrobial therapy plays a major (Himachal Pradesh, India) for serotyping.role in reducing incidence and mortality from avian In-vitro antibiotic sensitivity of the isolates were colibacillosis [2].Though many isolates of E. coli are assessed using disc diffusion method [7] using disc sensitive to several antibiotics, numbers of strains are coated with 15 antibacterial drugs (Hi-Media) viz.becoming resistant to common antibiotics especially ampicillin (A)-10µg, cephalexin (Cp) -30µg, those are widely used [2].Frequent occurrence of cephotaxime (Ce) -30µg, chloramphenicol (C) -30µg, respiratory, diarrhoea and joint problems caused by ciprofloxacin (Cf) -10µg, colistin (Cl) -10µg, co-E.colifollowing treatment with antibiotics indicates trimoxazole (Co) -25 µg, furazolidone(Fr) -50µg, drug resistant strains of the organism [3].Resistance to gentamicin (G) -10µg, nalidixic acid (Na) -30µg, nitro-intestine had congestion, haemorrhage, necrosis and furantoin (Nf) -300µg, norfloxacin(Nx) -10µg, oxy-desquamation.Focal areas of diphtheritic enteritis tetracycline (O) -30µg, streptomycin(S) -10µg and characterized by the presence of necrotic tissue with tetracycline (T) -30µg.Sensitivity was determined on heterophilic debrises were present over the intestinal the basis of diameter of the zone of inhibition around mucosa.In certain cases the mucosa showed vacuolation the disc as per the chart supplied by the firm (Hi-and flattening with occasional villus hypertrophy Media).
projecting towards intestinal lumen.Liver showed a After inoculation, the remaining parts of the organ thick layer of fibrinous exudates with large number of samples were preserved in 10 per cent formalin for heterophills over the hepatic capsule along with histopathological examination.Organs from those congestion and haemorrhage.The hepatocytes showed dead birds from which E.coli were recovered were early degenerative changes as well as focal necrosis processed according to the routine procedure for (Fig. 2.i).Lungs showed congestion with fibrinous histopathological studies [8].The paraffin embedded exudate and hemorrhages filling the bronchiolar tissues were cut into sections of 4 to 5 µ thickness and lumina.Presence of fibrinous sheets over the epicardial stained with Haematoxyline and Eosin (H & E) stain.
surface intermingling with heterophills, few mono Histopathological changes in the tissues were nuclear cells and erythrocytes were also noticed.recorded.
Kidneys revealed congestion and haemorrhages with focal areas of interstitial nephritis associated with

degeneration and areas of necrosis. Out of 150 samples, 91 samples yielded E.coli
Hjarre's disease or coligranuloma: The gross and based on cultural, morphological and biochemical microscopic lesions observed in three cases were characteristics.All the isolates were serotyped as E.coli suggestive of Hjarre's disease or coligranuloma.by National Salmonella and Escherichia Centre, Grossly, liver in two cases showed round and hard Central Research Institute, Kasauli (H.P.).Of these 91 caseated nodular structures on its surface, deeply isolates, 75 were typable, 6 rough and 10 untypable.
The duplicate section from these granulomas Grossly, the pigeon carcasses were highly congested.
stained by modified Gram's stain revealed gram-There were severe congestion and haemorrhage in the negative large rods morphologically indistinguishable intestinal mucosa and in some cases showed catarrhal from E. coli.enteritis.Fibrinous perihepatitis, pericarditis, and Discussion peritonitis were present in some cases.
Histopathologically, the mucosal epithelium of Majority of E.coli serotypes identified in this study, were reported to be potential pathogens for both large number of heterophills over the hepatic capsule young and old poultry, although the pathogenicity along with congestion and haemorrhage.The varies among different serotypes [9].In the present hepatocytes showed early degenerative changes as study, the most frequent serotype found was O157 well as focal necrosis.The changes in the liver and (9.89%), followed by O68, O121 (7.69%), O9, O75, intestine are possibly due to the response and reaction O131 (5.49%), O2, O13, O22 (3.30%).Strains belonging in detoxification and excretion of endotoxins, to sero-group O157, isolated in the present study were enterotoxin release by E.coli.earlier shown to be verocytotoxigenic [10].There is Lungs showed congestion with fibrinous exudate evidence of E. coli serotypes O133, O50, O79, O21, and haemorrhage filling the bronchiolar lumina.The O55, O2 and O125 in pigeon prevalent in Assam [11], similar changes like congestion, haemorrhage were [12].Multiple-antimicrobial-resistant APEC (Avian described by Phangcho [11].Pathogenic Escherichia coli) strains i.e.O78, O86, Presence of fibrinous sheets over the epicardial O141, O1 and O2 among rural chickens in the arid surface intermingling with heterophills, few mono region of north-eastern Nigeria [13] is also reported.
nuclear cells and erythrocytes were also noticed.Variation in feed and water supply along with Fibrinous exudates are due to acute inflammatory geographical variation might be the cause of variation reaction caused by toxin beta haemolycin released by in prevalence of serotypes.
E.coli resulting marked increased in vascular In-vitro antibiotic sensitivity of the isolates (Table -permeability.This violent type of injury leads to escape 1), revealed high sensitivity towards Ciprofloxacin of fibrinogen into the surrounding tissue [15].(96.70%) followed by Norfloxacin (93.41%),Kidneys revealed congestion and haemorrhages Gentamicin (91.21%),Chloramphenicol (76.92%) and with focal areas of interstitial nephritis associated with Cephotaxime (74.73%).Similar results have been degeneration and areas of necrosis.Degeneration and reported by earlier worker [13].Comparatively lower necrosis are due to E.coli toxins followed by susceptibility was recorded against Nitrofurantoin and inflammatory reaction leading to interstitial type of Tetracycline.Ampicillin was not at all effective [13], nephritis.The histopathological changes as observed in [14].Lower sensitivity of the isolates towards these the present study were also recorded by Ficken [16].drugs might be due to frequent and inadequate use in In coligranuloma, liver showed large granulothe pigeon.matous inflammatory reaction characterized by central Grossly, the pigeon carcasses were highly congested.
areas of caseo-necrosis occasionally mixed with Fibrinous perihepatitis, pericarditis, and peritonitis cellular debrices and at the periphery surrounded by were present in some cases.Haemorrhage and congestion epitheloid cells, lymphocytes and giant cells.The were observed in kidneys with congestion in various whole structure was surrounded by a connective tissue other organs indicating septicemic nature of the disease.
capsule leading to atrophy of the surrounding These findings agree with the earlier reports [11].
hepatocytes (Fig. 2.i & 2.ii).Similar granulomatous Histopathologically, the mucosal epithelium of lesions were also observed by earlier workers [17,18] intestine had congestion, haemorrhage, necrosis and in mesentery and serosal surface of intestine, liver and desquamation.Changes like desquamation, necrosis caecum.and heterophilic infiltration in the intestinal mucosa The pigeons may acquire infection from contawere also observed earlier workers [11].In certain minated environment, feed and water or from other cases the mucosa showed vacuolation and flattening carrier birds.But the commonest source of E. coli in with occasional villus hypertrophy projecting towards captive birds may be the bird's own commensals intestinal lumen indicating a concurrent viral infection.
intestinal flora which may cause the diseases under Liver showed a thick layer of fibrinous exudates with stressful conditions.such resistant strains might being potential danger to