Diarrheic Buffalo Calves Research Articles

Assessment of oxidative stress and mineral profile in diarrhoeic buffalo calves

Assessment of oxidative stress and mineral profile in diarrhoeic buffalo calves

Effect of albumin depletion on electrophoretic profile of plasma protein from diarrhoeic buffalo calves

Effect of albumin depletion on electrophoretic profile of plasma protein from diarrhoeic buffalo calves

Parasitological, Molecular, and Epidemiological Investigation of Cryptosporidium Infection Among Cattle and Buffalo Calves From Assiut Governorate, Upper Egypt: Current Status and Zoonotic Implications.

Details about the epidemiological patterns and real contributions of different reservoir animals in maintaining the transmission cycle of Cryptosporidium spp. in Upper Egypt remain lacking. This study was designed to investigate the occurrence of Cryptosporidium spp. in cattle and buffalo (n = 608) from Upper Egypt. The parasite for the resulting positive samples by fecal examination was molecularly identified using nested PCR targeting the small subunit rRNA. Moreover, several explanatory variables, including animals' age, sex, condition, seasonal variations, were examined to describe the epidemiological pattern of the disease. Interestingly, the fecal examination revealed that 33.55% (204/608) of the animals under study were infected with Cryptosporidium, including 38.27% among cattle and 28.16% among buffalo. The parasite was molecularly identified using nested PCR, and their amplicons were identified in almost all fecal samples using microscopy (202/204). According to age as an individual variable factor, the infection rates of Cryptosporidium spp. in cattle calves with ages of <1, 1–3, and >3 months were 39.13, 34.04, and 54.54%, respectively. Meanwhile, in buffalo calves, the occurrence rates were 28.57, 27.27, and 29.41%, respectively. Regarding sex, female cattle calves were more susceptible to Cryptosporidium infection (51.28%) than males (26.19%) (p < 0.05), whereas male buffalo calves had a higher infection rate (32.25%) than females (25%). According to seasonal variations, the infection rates of Cryptosporidium spp. in cattle calves during spring, summer, autumn, and winter were 42.11, 30.43, 30, and 52.63%, respectively. In contrast, lower infection rates of 30, 21.42, 23.52, and 35% were reported in buffalo calves during spring, summer, autumn, and winter, respectively. The rate of infection was 45.16% in diarrheic cattle calves and 15.78% in non-diarrheic ones (p < 0.05). Meanwhile, the infection rate was 33.96% in diarrheic buffalo calves and 11.11% in non-diarrheic ones (p < 0.05). This study reported a higher occurrence of Cryptosporidium infection among the animals under study and revealed that buffalos and cattle can contribute to maintaining the transmission cycle of this zoonotic parasite in Upper Egypt.

Epidemiology, molecular characterization and antimicrobial resistance of Necrotoxigenic Escherichia coli in diarrhoeic calves

A study was carried out to investigate the epidemiology, molecular characterization and antibiotic resistance of Necrotoxigenic E. coli (NTEC) isolated from diarrhoeic calves in Andhra Pradesh (AP) and Telangana States (TS). A total of 129 faecal samples from diarrhoeic buffalo calves of 1 to 90 days were collected from various districts in AP and TS, of which 60 E.coli were isolated. The cnf2 gene was detected by PCR and In vitro antibiotic susceptibility was tested by disk diffusion methods. The prevalence of E.coli associated diarrhea in calves was 46.51% of which 5.0% was due to NTEC based on the presence of cnf2 gene and none of the E.coli isolates possessed cnf1 gene. The NTEC isolates from diarrhoeic calves showed higher antibiotic resistance to tetracyclin and aztreonam (66.67%) and sensitive to ampicillin, cefotaxime, ceftazidime, amoxycillinclavulinicacid, gentamycin, kanamycin, streptomycin, sulfisoxazole, cotrimoxazole, ciprofloxacin, chloramphenicol and imipenem antibiotics. The present study provides baseline data on epidemiology of E.coli associated diarrhoeia, NTEC prevalence and antimicrobial resistance in calves which will help in formulating prophylactic and preventive measures in this geographic region.

Bovine Cryptosporidiosis and the Egyptian Diarrheic Buffalo Calves

The negative impact of diarrhea on livestock health is well known, Cryptosporidium, is one of the protozoan that causes diarrhea in calves especially buffalo calves. Some species of Cryptosporidium represent a zoonotic hazard. This study aimed to distinguish the potential species of Cryptosporidium in affected buffalo calves and evaluate a modified technique to improve the molecular detection and identification of Cryptosporidium. Twenty buffalo calves suffered from diarrhea were enrolled in the study. The enrollment criteria depended on the results of Ziehl–Neelsen stain. Sugar floatation technique was performed followed by oocyst concentration to form a pellet for DNA extraction. Multiplex PCR was performed for identification and differentiation of Cryptosporidium Spp. The results showed a mixed infection in 4 samples; the most common type of Cryptosporidium affecting the examined buffalo calves was C.parvum (10), followed by C.bovis (7 samples) and C.andersoni (6 samples) while no C.reyne was detected in the examined samples. The zoonotic type, C.parvum was found in 50% of the total affected animals. The current study detects three Cryptosporidium spp. namely C.parvum, C. andersoni, and C.bovis linked to diarrhea in the studied buffalo calves. Mixed infection with more than one species of Cryptosporidium was present. Standard detection of oocyte in fecal samples using modified Ziehl-Neelsen stain is a simple way for diagnosis of Cryptosporidium. However, a more sophisticated method is recommended to detect and differentiate the zoonotic species in calves, as they symbolize a crucial source of human infection.

Etio-Epidemiological Studies on Diarrhoea in Cattle and Buffalo Calves

Calf diarrhoea is the most commonly encountered disease syndrome and significant cause of economic losses in dairy industry. Present investigation was undertaken to find out the prevalence of causative agents of diarrhoea in the bovine calves for a period of one year. The effect of age, sex, season and parity of dam was also studied. E. coli was the major organism (86.00 %) observed in the faecal samples of the diarrhoeic calves followed by rotavirus, Eimeria spp. and Amphistomes (15.00 % each); Toxocara spp. (12.00 %); Strongyles (9.00 %); Cryptosporidium spp. (6.00 %); Trichuris spp. (5.00 %); and Salmonella spp. and Strongyloides spp. (3.00 % each). The prevalence of rotavirus, Cryptosporidium spp. and Eimeria spp. was found significantly higher in buffalo calves and crossbred calves than cow calves and Gir / local non-descript calves, respectively. The prevalence of Toxocara spp., Amphistomes and Strongyles in diarrhoeic buffalo calves was significantly higher than cow calves. Highest prevalence of E. coli and rotavirus was observed in faecal samples of diarrhoeic calves of 0-15 days age group. Rotavirus was not detected in faecal samples of diarrhoeic calves above 60 days age. The susceptibility of bovine calves for E. coli and rotavirus was found decreased with the advancement of the age. The prevalence of Salmonella spp. in diarrhoeic faecal samples of bovine calves was observed only in 16-60 days age whereas Cryptosporidium spp. was found only in 0-30 days age. The most of the parasitic infestations were observed after 30 days of age in calves. The calves of both sexes were equally susceptible to different causative agents of diarrhoea. The prevalence of E. coli and most of the helminth ova in the faecal samples of diarrhoeic calves was found maximum during rainy season whereas the rotavirus was observed mostly during winter season. The prevalence of E. coli, Salmonella spp., rotavirus and Cryptosporidium spp. was found highest in the faecal samples of the diarrhoeic calves of first or second parity dams.

Therapeutic management of acute calf diarrhoea in pre-weaned buffalo calves with herbal electrolyte combination regimens

Diverse pathobionts, undeveloped or disturbance in intestinal micro biota, unhygienic managemental practices, emergence of antibiotic resistant strain as a consequence of inappropriate use of antibiotic and various environment factors may account for acute calf diarrohea. Suppression of pathobionts and restoration of good intestinal health via use of herbal drug or synbiotics may be alternative strategy to combat diarrohea. The comparative therapeutic efficacy of different herbal-synbiotic formulations in combination with oral rehydration solution (ORS) were systematically evaluated in 24 diarrhoeic buffalo calves of either sex up to 12 weeks post-partum both in the organized and unorganized dairy farms in Jabalpur (Madhya Pradesh). The haemato-biochemical profiles of the diarrhoeic and apparently healthy calves were also monitored. The herbal anti-diarrhoreal agent (Kutaja/ Bael) in combination with synbiotics (prebiotics + probiotics) and ORS brought prompt relief to the diarrhoeic calves as evidenced by abatement of shooting diarrhoea, restoration of faecal consistency and the suckling impulse, improved skin tonicity and normal behaviour profile. The best results were obtained with the oral package: Kutaja+Synbiotic+ORS followed by Bael+Synbiotic+ORS clearly reflected in favourable changes in the internal milieu explored with the highly dependable haemato-biochemical indices.

Prevalence, molecular characterization and antimicrobial resistance of necrotoxigenic Escherichia coli in diarrhoeic buffalo calves

A study was carried out to investigate the prevalence, molecular characterization and antibiotic resistance pattern of Necrotoxigenic E. coli (NTEC) isolates from diarrhoeic buffalo calves in Andhra Pradesh (AP) and Telangana States (TS). A total of 375 faecal samples from diarrhoeic buffalo calves of 1 to 90 days old were collected from various districts in AP and TS, from which 302 E. coli strains (80.53%) were isolated. The cnf2 gene was detected by PCR and in vitro antimicrobial susceptibility was tested by disk diffusion methods. The prevalence of E. coli associated diarrhoea in buffalo calves was 85.04%, of which 11.26% was due to NTEC based on the presence of cnf2 gene. The NTEC pathotypes showed highest antimicrobial resistance of 55.88% to tetracycline followed by ampicillin (52.94) and aztreonam (41.18), while chloramphenicol (2.94%) and imipenem antibiotics were effective. The present study revealed that diarrhoeic buffalo calves are the important reservoirs of NTEC, which may pose a serious threat to human health in this geographic region.

A Study on the Correlation of Serum Electrolytes and Trace Elements along with Associated Risk Factors in Diarrheic Buffalo and Cattle Calves

A Study on the Correlation of Serum Electrolytes and Trace Elements along with Associated Risk Factors in Diarrheic Buffalo and Cattle Calves

Occurrence of Neglected Picobirna Virus in Buffalo Calves Associated with Diarrhoea

Picobirna viruses (PBVs) thought to be neglected viruses, are emerging as causative agents of viral gastrointestinal infections in human and other animal species with enteritis. In the present study, a total of 408 fecal samples of diarrheic buffalo calves of under age of 2 months were collected from different locations in Haryana. These samples were preliminarily screened for PBV by RNApolyacrylamide gel electrophoresis (RNA-PAGE). The RNA-PAGE positive samples were further confirmed by RT-PCR using RdRp gene specific primer pair PicoB25 (+) and PicoB43 (-) for amplification of genogroup I PBV that generated an amplicon of 201 bp. Out of 408 buffalo calves fecal samples, 52 (13%) samples were found positive for genogroup 1(GGI) PBV using RT-PCR. Genogroup II (GGII) specific primer generating 369 bp product size did not show amplification in any of the samples. The results suggested occurrence of PBV in Haryana State with predominance of GGI PBV. To the best of our knowledge, this is the first report of detection as well as occurrence of GGI picobirna virus among diarrheic buffalo calves in Haryana State.

Prevalence and molecular characterization of cryptosporidium species in buffalo calves of western Haryana

A sum total of 402 faecal samples from buffalo calves belonging to the age group of three months were collected randomly without any clinical symptom from various livestock farms and small holdings in four districts of Haryana. The presence or absence of Cryptosporidium spp. oocysts in faecal samples was confirmed by the standard microscopic examination of the modified Ziehl-Neelsen (MZN) stained faecal smears. The overall prevalence in buffalo calves was found to be 8.7%. The seasonal prevalence study revealed a maximum occurrence of Cryptosporidium infection during rainy followed by autumn, winters and minimum in summer season. Age related prevalence showed highest infection in calves between 16-30 days age which gradually decreased with increase in age. The DNA of representative positive faecal samples was extracted using standard phenol-chloroform-isoamylalcohol (PCI) method and then was subjected to nested PCR. All the extracted DNA were amplified for a 1325 bp primary fragment followed by a 834 bp nested fragment in a nested PCR of 18S rRNA gene, thereby confirming the presence of Cryptosporidium spp. The restricted enzyme digestion pattern (restricted fragment length polymorphism) of the 834 bp nested fragment using the restriction enzymes SspI and VspI confirmed the presence of C. parvum. Sequencing of Cryptosporidium DNA samples were carried out which also proved all samples to be of C. parvum. This is the first report of molecular identification of C. parvum in buffalo calves of Haryana and these Haryana isolates of Cryptosporidium parvum isolated from diarrhoeic buffalo calves are divergently related to rest of the part of the country isolates and indicates the zoonotic potential.

Serotyping, antibiotic susceptibility, and virulence genes screening of Escherichia coli isolates obtained from diarrheic buffalo calves in Egyptian farms.

Aim:In Egypt as in many other countries, river water buffalo (Bubalus bubalis) is considered an important source of high-quality milk and meat supply. The objective of this study was to investigate serotypes, virulence genes, and antibiotic resistance determinants profiles of Escherichia coli isolated from buffalo at some places in Egypt; noticibly, this issue was not discussed in the country yet.Materials and Methods:A number of 58 rectal samples were collected from diarrheic buffalo calves in different regions in Egypt, and bacteriological investigated for E. coli existence. The E. coli isolates were biochemically, serologicaly identified, tested for antibiotic susceptibility, and polymerase chain reaction (PCR) analyzed for the presence of antibiotic resistance determinants and virulence genes.Results:Overall 14 isolates typed as E. coli (24.1%); 6 were belonged to serogroup O78 (10.3%), followed by O125 (4 isolates, 6.9%), then O158 (3 isolates, 5.2%) and one isolate O8 (1.7%), among them, there were 5 E. coli isolates showed a picture of hemolysis (35.7%). The isolates exhibited a high resistance to β lactams over 60%, followed by sulfa (50%) and aminoglucoside (42.8%) group, in the same time the isolates were sensitive to quinolone, trimethoprim-sulfamethoxazole, tetracycline (100%), and cephalosporine groups (71.4%). A multiplex PCR was applied to the 14 E. coli isolates revealed that all were carrying at least one gene, as 10 carried blaTEM (71.4%), 8 Sul1 (57.1%), and 6 aadB (42.8%), and 9 isolates could be considered multidrug resistant (MDR) by an incidence of 64.3%. A PCR survey was stratified for the most important E. coli virulence genes, and showed the presence of Shiga toxins in 9 isolates carried either one or the two Stx genes (64.3%), 5 isolates carried hylA gene (35.7%), and eae in 2 isolates only (14.3%), all isolates carried at least one virulence gene except two (85.7%).Conclusion:The obtained data displayed that in Egypt, buffalo as well as other ruminants could be a potential source of MDR pathogenic E. coli variants which have a public health importance.

Prevalence and antimicrobial resistance pattern of Shiga toxigenic Escherichia coli in diarrheic buffalo calves.

Aim:Aim of the study was to investigate the prevalence, virulence gene profiles, and antimicrobial resistance pattern of Shiga toxigenic Escherichia coli (STEC) in diarrheic buffalo calves from Andhra Pradesh and Telangana States.Materials and Methods:A total of 375 fecal samples from diarrheic buffalo calves of 1-7, 8-30, 31-60, and 61-90 days age were collected from which STEC were isolated, and virulence genes were detected using multiplex polymerase chain reaction. The antimicrobial resistance of isolates was tested by disk diffusion method.Results:The prevalence of E. coli associated diarrhea in buffalo calves was 85.04%, of which 35.01% was STEC origin. In STEC, the combination of eaeA and, hlyA virulence genes was highest (42.45%) followed by stx1 (16.04%), stx1, stx2 and hlyA (13.21%), stx2 (12.64%), stx1, eae and hlyA (9.43%) and stx1 and hlyA (6.6%) genes were detected. Highest antimicrobial resistance was observed for tetracycline (63.21%) and ampicillin (48.11%), while chloramphenicol, gentamycin (96.33%) and imipenem (99.06%) antibiotics are susceptible. Multidrug resistance was detected in 69.81% of the STEC isolates from diarrheic buffalo calves.Conclusion:Higher prevalence of eaeA and hlyA genes carrying isolates of STEC may be a serious zoonotic threat and increased prevalence of multidrug resistance in E. coli may necessitate stringent selection of appropriate antimicrobial agent in treating buffalo calf diarrhea cases.

Molecular Characterization of Bovine Rotaviruses in Pakistan

Background: Group A bovine Rotaviruses (BRV) are one of the main factors of neonatal calf diarrhea and mortality around the world. The current study was carried out to assess the genetics of BRV circulating in the Pakistani livestock and characterize the antigenic genes of Rotavirus contributing towards calf diarrhea. Methods: A total of 200 fecal samples were collected from diarrheic buffalo and cattle calves from ten districts of Punjab, Pakistan. Samples were selected on the basis of agro-ecological zones of the province. Fecal samples were analyzed for the presence of BRV using Ag-capture ELISA. Positive samples were subjected to PCR for the amplification of VP4 and VP6 genes and subsequent sequencing. Phylodynamics was performed to infer genetic clustering and evolutionary distances of characterized strains of BRV in accordance to the BRV available publically. Results: In ELISA, a total of 12 calf samples (5 cattle and 7 buffalo), 6%, were found positive. The sequencing and phylogenetic analysis of both genes showed that Pakistani BRV (BRV/QOL/13) depicted maximum identity (98%) of the VP4 gene with Indian BRV VP4 gene. Pakistani BRV VP6 gene (Pakistan/MM85/QOL) showed maximum identity of 98% with Indian BRV A VP6 gene (accession No. JF720873, EF200565). Conclusions: Bovine rotavirus presents 6% of calf diarrhea in Pakistani cattle and buffalo samples. The VP4 and VP6 genes show closed relationships with bovine rotavirus reported from Indian isolates.

Clinical and Laboratory Studies on Diarrhea Problem in Newborn Calves

The study was carried on a total number of 130 calves. From them 53 buffalo calves were held in the animal farm station of Faculty of Veterinary Medicine, Suez Canal University and 77 Frisian cattle calves were held in El-Salhya private farm, Ismailia, Egypt. Two control groups 9 from the faculty farm and 11 for El-Salhya farm were used from each group. All groups were clinically examined for presence of fever, signs of diarrhea and dehydration. Blood with and without anticoagulant and fecal samples were collected from both diseased and control calves at the same time. Heparinized blood was used for blood picture. Clear serum samples were used for biochemical analysis of sodium, potassium, chloride, total proteins, albumin and globulins as well as Protein electrophoresis pattern was performed to detect the level of each protein fraction. Fecal samples were examined microscopically to detect the presence of parasitic infestation. According to the severity of dehydration the diseased calves were divided into three groups mild, moderate and severe one. Diseased calves showed mild to severe diarrhea and few cases showed signs of dehydration. Hematological findings revealed no significant variations in hemoglobin values and leukocyte counts but RBCs counts showed a significant decrease in mild cases of diarrheic calves; however PCV showed a highly significant increase in severe diarrheic calves in both farms. Biochemical analysis of serum showed no significant differences in sodium and potassium, while chloride showed highly significant increase in severe diarrheic buffalo calves. Total proteins showed a significant increase in severe diarrheic buffalo calves in the faculty farm, while albumin showed a significant increase in severe group of El-salhya farm, also globulin showed a significant increase in all diseased buffalo calves. Protein electrophoresis revealed that only α1 globulins showed highly significant increase in diseased calves. No severe blood changes were recorded. The obtained result support the idea that mild diarrhea does not affect blood parameters in early stages of the disease.

Predominance of G10 Genotype of Rotavirus in Diarrheic Buffalo Calves: A Potential Threat for Animal to Human Zoonotic Transmission

Predominance of G10 Genotype of Rotavirus in Diarrheic Buffalo Calves: A Potential Threat for Animal to Human Zoonotic Transmission

Concurrent Infection of Rotavirus and Shiga ToxigenicEscherichia coli(STEC) in Buffalo Calves in Mumbai Metropolis, Western India

Faecal samples from 113 diarrhoeic cattle and buffalo calves less than one year of age, from different farms in Mumbai metropolis in India, were screened for the presence of Rotavirus and Shiga toxin-producing Escherichia coli (STEC). RNA-Poly acrylamide gel electrophoresis (RNA-PAGE) analysis of these samples revealed 11 (9.73%) as positive for group A rotavirus (GARV). Out of 11 samples found positive by RNA-PAGE, which were subjected to amplification of VP7 gene of GARV, 10 samples yielded a specific product of 1, 013 bp. The incidence of Shiga toxigenic E. coliin diarrhoeic buffalo calves was 13.23% (9 out of 68) and 6.66% in the cattle calves (3 out of 45) as demonstrated by multiplex polymerase chain reaction (PCR) of the shiga toxin (stx) genes. Eight (66.66%) isolates carried stx2 gene and four (33.33%) isolates had stx1 gene. To the best of our knowledge, we report for the first time the concurrent infection of Shiga toxigenic E. coli and GARV (6 cases; 8.82%) in diarrhoeic faecal samples of buffalo calves from India.

ISOLATION OF SALMONELLA SPECIES FROM BUFFALO CALVES MEAT AND PRELIMINARY EVALUATION OF ITS IRRADIATED VACCINE

The bacteriological examination of 200 meat samples obtained from diarrheic buffalo calves revealed that Salmonella isolates could be recovered with an incidence 2 %. Serological identification of Salmonella species by using O and H antisera revealed that the most common Salmonella serovars were Salmonella typhimurium followed by Salmonella dublin and Salmonella anatum with an incidence 1 %, 0.5% and 0.5 % respectively. Salmonella typhimurium is inactivated by 3 KGy dose of irradiation of meat and also the isolated organism for preparation of the vaccine. The result of vaccination inoculation challenge studies revealed that the prepared Salmonella typhimurium vaccine was effective in protecting rabbits from salmonellosis.

USING OF TRADITIONAL AND QUANTITATIVE CYTOCHEMICAL METHODS FOR IDENTIFICATION AND ENZYME CHARACTERIZATION OF SOME E.COLI SEROGROUPS CAUSING ENTERITIS IN BUFFALOES

Enteritis is most fatal disease especially for neonatal and young buffalo calves. Out of 150 fecal samples, 100 from diarrheic and 50 from non diarrheic (apparently healthy) buffalo calves were collected from private farms for isolation and identification of E.coli using morphological, cultural, biochemical and serological examination. Further cytochemical enzyme characterization of the different identified serogroups were carried out through the cytochemical quantitative determination of bacterial mitochondrial Adenosene-tri phosphatase (ATP-ase) and succinic dehydrogenase (SDH-ase) enzyme activities for their possible variations among the isolated and identified E.coli serogroups. Four values to each of E.coli serogroup (2 for each enzyme) as optical densities (OD.) could be obtained : (ATP-ase activity & Actual ATP-ase reaction and SDH-ase activity & Actual SDH-ase reaction) for E.coli-serogroups: E.coli O26, E.coli O55, E.coli O78, E.coli O86 and E.coli O111 as following: (0.595 & 0.285 and 0.560 & 0.210), (0.565 & 0.265 and 0.550 & 0.200), (0.590 & 0.255 and 0.540 & 0.190), (0.590 & 0.205 and 0.490 & 0.180) and (0.600 & 0.160 and 0.560 & 0.150) nm respectively. It was observed that the SDH-ase enzyme activity differentiate between the majority of the studied E.coli-serogroups for the significant (P≤0.05) variations between their enzyme activities (except between the serogroups E.coli O26 and E.coli O111 which showed the same (non-significant) SDH-ase activity, but ATP-ase enzyme activity could not differentiate between the different E.coli serogroups because of its non-significant variations among different serogroups (except with the serogroup E.coli O55 which showed the significant lower ATP-ase enzyme activity and noted to be lower pathogenic than the other E.coli serogroups), so that the actual ATP-ase enzyme activities (the difference between the OD. after and before incubation period) may be used for differentiation between different serogroups. Further cytochemical characterization to other bacterial enzymes and to other E.coli serogroups should be carried out as additional tool for a definite differentiation and characterization of E.coli serogroups causing enteritis in buffalo calves.

Comparative mutant prevention concentration and antibacterial activity of fluoroquinolones against Escherichia coli in diarrheic buffalo calves

Owing to emerging threat of antimicrobial resistance, mutant prevention concentration (MPC) is considered as an important parameter to evaluate the antimicrobials for their capacity to restrict/allow the emergence of resistant mutants. Therefore, MPCs of ciprofloxacin, enrofloxacin, levofloxacin, moxifloxacin, and norfloxacin were determined against Escherichia coli isolates of diarrheic buffalo calves. The minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) were also established. The MICs of ciprofloxacin, enrofloxacin, levofloxacin, moxifloxacin and norfloxacin were 0·009, 0·022, 0·024, 0·028, and 0·036 μg/ml, respectively. The MBCs obtained were very close to the MICs of respective drugs that suggested a bactericidal mode of action of antimicrobials. The MPCs (μg/ml) of ciprofloxacin (4·2×MIC), moxifloxacin (4·8×MIC), and norfloxacin (5·1×MIC) were approximately equal but slightly lower than enrofloxacin (7·6×MIC) and levofloxacin (8·5×MIC) against clinical isolates of E. coli. The MPC data suggested that enrofloxacin has the potential for restricting the selection of E. coli mutants during treatment at appropriate dosing.