Bacteriological culture of blood from critically ill neonatal calves.

The objectives of this study were to estimate the prevalence of bacteremia in critically ill, neonatal calves with severe diarrhea or depression, and to describe the variety of bacteria involved. Two studies were conducted in the summers of 1991 and 1993 involving 190 neonatal calves, 1-day to 19-days-old. Bacteremia was detected by blood culture in 31% (28/90) of calves in study 1, and in 24% (19/79) of ill calves and 0% (0/21) of control calves in study 2. Bacteria cultured from blood included Escherichia coli (51% of all isolates), other gram-negative enterics (25.5%), gram-negative anaerobes (5.9%), gram-positive cocci (11.8%), and gram-positive rods (5.9%). Among clinically ill calves, the average age was significantly lower in the blood culture-negative group (5.5 d) than in the blood culture-positive group (7.5 d) (P = 0.004). Mean serum IgG concentration was significantly (P = 0.0001) lower in blood culture-positive calves (1.146 g/L) than in blood culture-negative calves (3.077 g/L). The mortality rate was significantly (P < 0.0001) higher in the blood culture-positive group (57.4%) than in the blood culture-negative group (15.1%). Bacteremia appeared to be a frequent entity in this particular rearing situation. Early recognition of the problem, as well as appropriate treatment, may be beneficial in increasing survival rates. Results also support the need to address the failure of passive transfer of maternal antibodies to prevent bacteremia in calves.     

Use of blood culture medium enrichment for synovial fluid culture in horses: A comparison of different culture methods

Reasons for performing study: Standard methods for culturing equine synovial fluid (SF) are often unrewarding. Evidence‐based information on the relative efficiency of different systems used for optimisation of isolation of microorganisms from equine SF is lacking. Objectives: To compare the results of different culture systems performed in parallel on SF samples from horses clinically diagnosed with synovial sepsis. Methods: Synovial fluid specimens were collected between February 2007 and October 2008 from all horses admitted to a referral hospital that were clinically diagnosed with synovial sepsis and from control horses. Synovial fluid samples were cultured in parallel by: 1) direct agar culture (DA); agar culture after: 2) lysis‐centrifugation pretreatment (LC); 3) conventional enrichment (CE); 4) combined LC/CE; or 5) blood culture medium enrichment using an automated system (BACTEC 9050). Results: Ninety SF samples from 82 horses were included, together with 40 control samples. Seventy‐one of 90 samples (79%) were culture‐positive by using blood culture medium enrichment (BACTEC), which was significantly higher compared to all other methods. BACTEC enrichment was never negative while any of the other methods was positive. Although agar culture following LC and/or CE resulted in a slightly higher number of positive samples compared to DA, this difference was not significant. All control samples were culture negative by the 5 different techniques. Although the majority of samples containing isolates recovered without enrichment, culture results after BACTEC enrichment were available on the same day as for agar culture with or without LC (19/23 samples), while CE postponed recovery by at least one day in 20/23 samples. Conclusion: Blood culture medium enrichment is superior to other techniques for isolation of bacteria from SF of horses. The use of an automated system allows enrichment without substantially postponing recovery of microorganisms. Potential relevance: The efficient and fast isolation of microorganisms from infected SF by the BACTEC system allows for rapid susceptibility testing and a more appropriate antibiotic treatment.     

Characterisation of avian pathogenic Escherichia coli (APEC) associated with colisepticaemia compared to faecal isolates from healthy birds

A total of 114 avian pathogenic Escherichia coli (APEC) isolates were collected from cases of colisepticaemia occurring in broilers (77) and layers (37) within Ireland. In addition 45 strains isolated from faeces of healthy birds were included for comparison. All isolates were serogrouped, and examined for known virulence factors, mostly by PCR. The O78 serogroup represented 55 and 27% of broiler and layer colisepticaemic isolates respectively. All isolates were positive for curli fimbriae (crl, csg) and negative for afimbrial adhesin (afa). S-fimbrial (sfa) sequences were present in 8.8% of septicaemic isolates and 8.9% of healthy bird isolates. The majority of E. coli from cases of colisepticaemia (97.4%) and healthy bird (95.6%) isolates were positive for aerobactin (aer), and temperature sensitive haemagglutinin (tsh) was similarly detected in high numbers in 93.9 and 93.3%, respectively. In comparison to E. coli isolates from the faeces of healthy birds, a significantly higher percentage of isolates from septicaemic cases possessed Type 1 fimbriae (fimC) and increased serum survival (iss) gene sequences. Forty-seven (41.2%) isolates from septicaemic birds possessed P-fimbriae (pap) gene sequences, compared with only 15.6% from E. coli isolated from healthy birds. Haemolysin (hlyE) sequences were detected in 46.7% of isolates from healthy birds in comparison with 6.1% of septicaemic isolates. Sequences encoding colicin V (cvaC) were detected in 99.1% of septicaemic isolates and 82.2% of isolates from healthy birds. The K1 capsule was only present in two septicaemic isolates, both taken from layers. Motility was detected in 36.8% of E. coli isolated from cases of septicaemia, compared with 93.3% of isolates from healthy birds. These results demonstrate the presence of 11 virulence genes in E. coli isolated from cases of colisepticaemia within Ireland, and indicate the prevalence of iss and fimC.     

Development of a sandwich ELISA and comparison with PCR for the detection of F11 and F165 fimbriated Escherichia coli isolates from septicaemic disease in farm animals

The P fimbriae F11 and F165 that have been demonstrated on Escherichia coli septicaemic strains in poultry and calves, respectively, possess a nearly identical major subunit that demonstrates a serological cross-reaction. A polyclonal antibody-based sandwich ELISA (sELISA) that was specific for both F11 and F165 fimbriated strains was compared with a PCR method to detect F11/F165 fimbriated strains, in a collection of E. coli strains isolated from diseased animals. Of 298 isolates tested, 36 were positive by PCR of which only 14 were sELISA positive. There were no sELISA positive but PCR negative results. The 36 PCR positive isolates comprised 11 avian strains of which 10 were sELISA positive, 20 bovine strains of which 4 were sELISA positive and 3 ovine strains, 1 porcine strain and 1 equine strain all of which were sELISA negative. The F11/F165 incidence of 10.7% in 103 poultry and 18.3% in 109 bovine isolates demonstrates a moderate level of these factors in E. coli septicaemic cases in Northern Ireland.     

A possible role for Clostridium difficile in the etiology of calf enteritis

Clostridium difficile was investigated as a possible cause of enteritis in calves. The organism and its toxins (TcdA and TcdB), respectively, were found in 25.3% and 22.9% of stool samples from diarrheic calves. Culture positive samples were more likely than culture negative samples to be toxin positive. However, toxin positive stools were more common among nondiarrheic calves, but diarrheic calves were nearly twice as likely to be culture positive. Ribotype 078 was dominant among isolates. Salmonella sp. was isolated from both diarrheic and nondiarrheic calves, but large numbers of E. coli were found more commonly in diarrheic calves than in nondiarrheic animals. Prevalence rates for coronavirus and Cryptosporidium sp. were substantially higher in nondiarrheic calves than in diarrheic, but rates of detection of rotavirus and Giardia sp. were more nearly equal between groups. Lesions in naturally infected calves included superficial mucosal erosion with associated fibrinous exudates. Neutrophils and eosinophils infiltrated lamina propria. Large Gram-positive rods morphologically compatible with C. difficile were abundant in the colonic lumen and the organism was isolated by bacteriologic culture. Toxins were found throughout the colon. Purified toxins A and B (individually and conjointly) caused comparable lesions, as well as fluid accumulation, in ligated intestinal loops. Our findings are in substantial agreement with those of others [Rodriguez-Palacios, A., Stampfli, H.R., Duffield, T., Peregrine, A.S., Trotz-Williams, L.A., Arroyo, L.G., Brazier, J.S., Weese, J.S., 2006. Clostridium difficile PCR ribotypes in calves, Canada. Emerg. Infect. Dis. 12, 1730-1736; Porter, M.C., Reggiardo, C., Bueschel, D.M., Keel, M.K., Songer, J.G., 2002. Association of Clostridium difficile with bovine neonatal diarrhea. Proc. 45th Ann. Mtg. Amer. Assoc. Vet. Lab. Diagn., St. Louis, MO, U.S.A.] and add strength to a working hypothesis that C. difficile infection and the accompanying intoxication can manifest as diarrhea in calves. It seems clear that calves serve as multiplying hosts for this organism.     

Occurrence and characteristics of CS31A antigen-producing Escherichia coli in calves with diarrhoea and septicaemia in Argentina

CS31A is a K88-related non-fimbrial adhesin first described on Escherichia coli strains isolated from diarrhoeic and septicaemic calves. In this report, CS31A antigen was screened by immunological methods and confirmed by PCR among bovine E. coli isolates. In addition, CS31A-producing strains were characterized with respect to different fimbrial antigens, O-serogroup and other properties related to virulence. Faecal or tissue specimens of 100 diarrhoeic or septicaemic calves and 27 older cattle with different pathologies from 71 outbreaks or individual cases that occurred in Buenos Aires province, Argentina, were examined. CS31A + E. coli strains were isolated from 21 (21.0%) calves from 16 outbreaks or individual cases. No CS31A + E. coli was detected in samples from cattle more than 1 year old. Fimbriae F5, F41, F17a and F17b were not detected among the CS31A-producing strains. Three (14.3%) of the CS31A+ E. coli strains expressed the F17c fimbria. All of the 21 isolates exhibited at least one property of septicaemic strains (resistance to serum, production of aerobactin or colicins) but none of them demonstrated heat-stable enterotoxigenic activity. CS31A + E. coli isolates belonged to 10 serogroups, more commonly O8, O7, O17 and O21. The results obtained here confirm the worldwide distribution of CS31A antigen in bovine E. coli strains. However, CS31A + or CS31A + /F17c + E. coli were less frequently isolated than they were in North hemisphere countries.     

Pathotyping and antimicrobial susceptibility testing of Escherichia coli isolates from neonatal calves

Neonatal calf mortality is a major concern to livestock sector worldwide. Neonatal calf diarrhoea (NCD), an acute severe condition causes morbidity and mortality in calves. Amongst various pathogens involved in NCD, E. coli is considered as one of the major causes. The study was targeted to characterize E. coli isolates from neonatal calves for diarrhoeagenic Escherichia coli (DEC) types (pathotyping), antimicrobial resistance (AMR) profiling and to correlate with epidemiological parameters. From neonates, a total of 113 faecal samples were collected, out of that 308, lactose fermenting colonies were confirmed as E. coli. Pathotypable isolates (12.3%) were represented by STEC (6.1%), EPEC (2.9%), ETEC (1.9%), EAEC (0.9%) and EHEC (0.3%). Occurrence of STEC was more in non-diarrhoeic calves, whereas ETEC was observed more in diarrhoeic calves. EPEC occurrence was observed in both diarrhoeic and non-diarrhoeic calves. Fishers extract test showed no significant association for occurrence of DEC types to type of dairies, health status, species, breed, age and sex of neonatal calves. Two hundred and eighty isolates were tested for antimicrobial susceptibility. The isolates showed maximum resistance towards ampicillin (55.4%) followed by tetracycline (54.3%), while minimum resistance was observed towards meropenem (2.5%). Multidrug resistant E. coli isolates were found to be 139 (49.6%), and Extended-spectrum beta-lactamase (ESBL) producers were 120 (42.9%). DEC pathotypes like STEC, ETEC, EHEC and EAEC that are also multidrug resistant present in neonatal calves have zoonotic potential and hence are of public health significance.

     

Determinants and Utility of the Anion Gap in Predicting Hyperlactatemia in Cattle

The objectives of this study were to investigate the determinants of the anion gap (AG) in cattle and to evaluate the utility of AG in detecting hyperlactatemia in sick neonatal calves and adult cattle. The AG was calculated as AG = ([Na+] + [K+]) - ([Cl^-] + [HCO₃]), with all values in mEq/L. The AG of healthy neonatal calves (n = 16) was 29.6 ± 6.2 mEq/L (mean ± SD), and the blood L-lactate concentration ranged from 0.5 to 1.2 mM/L. The AG was significantly (P > .05) correlated with serum phosphate (r = .66) and creatinine (r = .51) concentrations. The AG of neonatal calves with experimentally induced diarrhea (n = 16) was 28.6 ± 5.6 mEq/L, and the blood L-lactate concentration ranged from 1.1 to 2.9 mM/L. The AG was significantly correlated with blood L-lactate concentration (r = .67), serum phosphate concentration (r = .63), creatinine concentration (r = .76), and blood pH (r = -.61). The AG of adult cattle with abomasal volvulus (n = 41) was 20.5 ± 7.8 mEq/L, and the blood L-lactate concentration ranged from 0.6 to 15.6 mM/L. The AG was significantly correlated with blood L-lactate concentration (r = .60), serum phosphate concentration (r = .71), creatinine concentration (r = .65), albumin concentration (r = .47), total protein concentration (r = .54), blood pyruvate concentration (r = .67), and blood pH (r = -.41) but not plasma β-OH butyrate concentration. The results indicate that the AG in cattle is only moderately correlated with blood L-lactate concentration and is similarly correlated with serum phosphate and creatinine concentrations in neonatal calves and adult cattle, as well as with serum albumin and total protein concentrations in adult cattle. Anion gap determination is of limited usefulness in predicting blood L-lactate concentration in sick cattle, whereas the correlation between AG and serum creatinine concentration in sick cattle suggests that an increased AG should alert the clinician to the potential presence of uremic anions.     

Comparison of BACTEC 460 and MGIT 960 systems for the culture of Mycobacterium avium subsp. paratuberculosis S strain and observations on the effect of inclusion of ampicillin in culture media to reduce contamination

To compare the utility and diagnostic accuracy of BACTEC and MGIT culture systems, a total of 41 pooled faecal samples, each containing faeces from one sheep infected with the S strain of Mycobacterium paratuberculosis and four uninfected sheep was cultured. The MGIT culture system did not support the growth of the S strain of M. paratuberculosis from faeces within the time frame of the experiments, although a laboratory adapted S strain grew slowly in MGIT provided that sufficient bacteria were inoculated. In contrast, C strain grew rapidly in MGIT. The sensitivity of culture was calculated relative to the infection status of the animals, none of which had clinical signs of ovine Johne's disease. The overall sensitivity of pooled faecal culture in the BACTEC culture system was 21.9% (95% confidence limits, 10.5-37.6), a figure dependant on the proportion of multibacillary cases. The sensitivities of the BACTEC culture system for pools containing animals with multibacillary and paucibacillary lesions were 100.0% (95% confidence limits, 47.2-100.0) and 17.8% (95% confidence limits 6.06-36.8), respectively. The contamination rate of BACTEC cultures was 9.7% compared to 14.3% for MGIT. The effect of 100 microg/ml ampicillin on the S strain of the M. paratuberculosis was examined and in both BACTEC and MGIT media it delayed growth by about 1 week. The composition of MGIT medium, particularly presence of vancomycin hydrochloride, slowed the growth of the S strain. The low content of egg yolk was considered to be another possible factor. The radiometric BACTEC culture system remains the best alternative for the culture of S strain and is recommended in circumstances where the genotype (s) of the strains present in a region/farm is either unknown or S strain.     

Salmonella infections in neonatal dairy calves.

To estimate herd prevalence of Salmonella spp, fecal specimens were obtained for culture from neonatal calves of 47 Ohio dairy herds. Of the 452 calves tested, 10 calves from 7 farms were culture-positive. Salmonella serotypes isolated were S dublin, S typhimurium, S enteritidis, S agona, S mbandaka, and S montevideo. Bulk tank milk filters from these dairies were also submitted for culture. Salmonella sp was isolated from 1 of the 50 filters, and 2 calves from this herd were found to be shedding Salmonella sp of the same serotype.     

Natural and experimental infection of neonatal calves with Clostridium difficile

Clostridium difficile toxins were associated with calf diarrhea in a recent retrospective study; however, no causal relationship has been prospectively investigated. This infection study tested whether the oral inoculation of neonatal calves with a toxigenic strain of C. difficile (PCR-ribotype 077) results in enteric disease. Fourteen 6-24 h old male colostrums-fed Holstein calves, received either three doses of C. difficile (1.4 x 10(8) +/- 3.5 x 10(8) cfu) (n = 8) or sterile culture broth (n = 6). Calves were euthanized on day 6 or after the onset of diarrhea, whichever came first. Fecal and intestinal samples were blindly cultured for C. difficile, and tested for its toxin A/B (C. difficile TOX A/B II ELISA, Techlab). PCR-ribotyping was used to compare inoculated and recovered isolates. Diarrhea was observed in all control calves and 3/8 of inoculated calves (p = 0.03), but it did not occur in calves that tested positive for C. difficile toxins. Fecal toxins were identified only from two controls. PCR-ribotyping confirmed the presence of C. difficile PCR-ribotype 077 in samples of all inoculated calves, but not from controls. The identification of five other PCR-ribotypes in 3/8 (37.5%) and 2/6 (33.3%) of inoculated and control calves, respectively, indicated early natural infection (< or = 24h of age). Five of 14 cecal samples had C. difficile (p = 0.01). In conclusion, the oral administration of C. difficile PCR-ribotype 077 to neonatal calves resulted in fecal/intestinal colonization but not in detection of toxins, or signs of enteric disease. Further studies are required to investigate the clinical relevance of C. difficile in calves.     

Occurrence and Characteristics of CS31A Antigen‐Producing Escherichia coli in Calves with Diarrhoea and Septicaemia in Argentina

CS31A is a K88‐related non‐fimbrial adhesin first described on Escherichia coli strains isolated from diarrhoeic and septicaemic calves. In this report, CS31A antigen was screened by immunological methods and confirmed by PCR among bovine E. coli isolates. In addition, CS31A‐producing strains were characterized with respect to different fimbrial antigens, O‐serogroup and other properties related to virulence. Faecal or tissue specimens of 100 diarrhoeic or septicaemic calves and 27 older cattle with different pathologies from 71 outbreaks or individual cases that occurred in Buenos Aires province, Argentina, were examined. CS31A+ E. coli strains were isolated from 21 (21.0%) calves from 16 outbreaks or individual cases. No CS31A+ E. coli was detected in samples from cattle more than 1 year old. Fimbriae F5, F41, F17a and F17b were not detected among the CS31A‐producing strains. Three (14.3%) of the CS31A+ E. coli strains expressed the F17c fimbria. All of the 21 isolates exhibited at least one property of septicaemic strains (resistance to serum, production of aerobactin or colicins) but none of them demonstrated heat‐stable enterotoxigenic activity. CS31A+ E. coli isolates belonged to 10 serogroups, more commonly O8, O7, O17 and O21. The results obtained here confirm the worldwide distribution of CS31A antigen in bovine E. coli strains. However, CS31A+ or CS31A+/F17c+ E. coli were less frequently isolated than they were in North hemisphere countries.     

Identification of virulence factors by multiplex PCR in Escherichia coli isolated from calves in Minas Gerais, Brazil

In this study, multiplex PCR was employed to investigate the virulence factors of Escherichia coli strains isolated from 60-day-old calves. Faecal samples were collected from 54 calves at 12 dairy farms in the state of Minas Gerais, Brazil. A total of 156 isolates were obtained after culture and microbiological isolation and were tested by multiplex PCR for the presence of genes encoding toxins (Stx1, Stx2 and STa) and adherence factors (intimin, F41 and F5). Seventy of 156 isolates were positive for at least one virulence factor: ten (14.3?%) from diarrhoeic animals and 60 (85.7?%) from healthy calves. The virulence markers identified were: Stx1 (82.8?%), eae (24.3?%), F41 (11.4?%), F5 (10?%), STa (4.28?%) and Stx2 (4?%). In diarrhoeic animals, Stx1 (70?%) and F41 (30?%) were identified, while Stx1 (83.3?%), eae (28.3?%), F41 (8.3?%), F5 (11.6?%), STa (5?%) and Stx2 (1.6?%) were detected in isolates from healthy calves. Mixed infections with pathotypes Shiga toxin-producing E. coli (STEC)/enteropathogenic E. coli, STEC/enterohaemorrhagic E. coli and STEC/other (eae/F5, Stx1/STa) were detected in five healthy calves. Pathogenic E. coli were identified in 59.26?% of all calves and on 75?% of the dairy farms studied, not only in diarrhoeic (five of six) but also in healthy calves (27 of 48), which demonstrates the importance of this agent in the aetiology of diarrhoea in calves in the state of Minas Gerais.     

Comparison of the recovery of Mycobacterium bovis isolates using the BACTEC MGIT 960 system, BACTEC 460 system, and Middlebrook 7H10 and 7H11 solid media.

The BACTEC Microbacteria Growth Indicator Tube (MGIT) 960 system was evaluated to determine how it compares with the BACTEC 460 radiometric system and solid media for recovery of Mycobacterium bovis from tissue samples. A total of 506 bovine lymph node samples were collected from abattoirs in the United States and Mexico between November 2003 and September 2004. Processed samples were inoculated into an MGIT 960 tube, BACTEC 460 vial, and Middlebrook 7H10 and Middlebrook 7H11 solid media. Ziehl-Neelsen slides were prepared to check for contaminants and confirm the presence of acid-fast positive bacilli. Samples containing acid-fast bacilli were confirmed as members of the Mycobacterium tuberculosis complex by a nucleic acid assay. Niacin and nitrate biochemical tests were used to distinguish M. bovis from M. tuberculosis isolates. Statistical analyses were performed to compare recovery rate, mean time to detection, contamination rates, as well as pair-wise comparisons in each category. The results showed that the MGIT 960 system had a higher recovery rate of M. bovis (122/129) than did the BACTEC 460 (102/129) and solid media system (96/129). The average time to detection was 15.8 days for the MGIT 960 system, 28.2 days for the BACTEC 460 system, and 43.4 days for solid media. Contamination rates were 6.9% for the MGIT 960 system, 3.4% for the BACTEC 460 system, and 21.7% for solid media. These results indicate the MGIT 960 system can be used as an alternative to the BACTEC 460 system for recovering M. bovis from tissue samples.     

Bacteremia in equine neonatal diarrhea: a retrospective study (1990-2007)

Background: Bacteremia in sick foals is associated with survival, but the association of bacteremia and diarrhea is not reported.
Hypothesis: Neonatal foals with diarrhea will commonly be bacteremic.
Animals: One hundred and thirty-three neonatal foals.
Methods: Records of all foals <30 days of age presenting with diarrhea between January 1990 and September 2007 were reviewed.
Results: Sixty-six of 133 foals (50%) were bacteremic at admission, with 75 isolates from the 66 samples. The blood culture from a further 18 foals (13.5%) grew coryneform bacteria. Nine foals (6.8%) had 2 or more organisms grown on blood culture. One foal had 5 different organisms, interpreted as contamination. Forty-eight foals (36%) had no growth on admission blood cultures. No cultures isolated fungal organisms. Excluding coryneform bacteria, 43 isolates (57%) were Gram-negative organisms and 32 isolates (43%) were Gram-positive organisms. The most common isolate was Enterococcus spp. (22 isolates, 29%), followed by Pantoea agglomerans (13 isolates, 17%). IgG concentration at admission was not associated with blood culture status. Blood culture status was not associated with survival to hospital discharge.
Conclusions and Clinical Importance: Bacteremia is common in neonatal foals with diarrhea. Decisions regarding antimicrobial selection should be made with these differences in mind.     

Isospora orlovi infection in suckling dromedary camel calves (Camelus dromedarius) in Kenya

Outbreaks of isosporosis in young suckling dromedary camel calves (Camelus dromedarius) in Dubai, UAE and in Kenya were recently described. In the former outbreak the pathogen was shown to be Isospora orlovi by morphological features and was later characterized molecularly. In the present study, we have made a longitudinal investigation of 159 suckling dromedary calves < or =12 weeks of age belonging to 8 ranched camel herds (M1) in Northern Kenya. The study was carried out during 18 months. In three of the herds frequent samples were taken irregularly every 1-6 weeks. All calves < or =12 weeks of age present in the respective herds were sampled during the visits. In addition, 91 calves of the same age group but belonging to 42 pastoral herds (M2) in Northern Kenya were point sampled at convenience. Faecal samples from each calf were taken and the faeces were investigated for coccidia. Samples found with coccidian oocysts were suspended in a 2% potassium dichromate solution. Isospora sp. was identified and samples with relatively high numbers of Isospora sp. were analysed molecularly. The SSU rRNA gene and internal transcribed spacer 1 (ITS1) were amplified with primers complementary to conserved regions of the SSU rRNA gene in eukaryotes as well as a conserved part of the 5.8S rRNA gene of Eimeria. A relatively high number of the calves exhibited diarrhoea, 30.2% and 41.8% in the M1 and M2 herds, respectively. Isospora sp. was only found in diarrhoeic calves or in calves convalescent from recent scouring periods. No calf >8 weeks of age was found to be excreting Isospora sp. The parasite was only found in calves < or =4 weeks of age in the M1 herds and in the M2 herds in calves <8 weeks of age. Of the M1 and M2 calves exhibiting diarrhoea, 20.8% and 26.3% excreted Isospora sp., respectively. Morphologically the Isospora sp. was similar to I. orlovi and sequence analysis of the SSU rRNA gene from four Kenyan isolates (unfortunately only from the pastoral herds, M2) and ITS 1 segments from three of the isolates from Kenya and one from Dubai, confirmed that the Isospora isolates belonged to the species I. orlovi, and that the sequences were similar to the Dubai isolates.     

Meningitis in neonatal calves: 32 cases (1983-1990).

Case records of 32 neonatal calves with the antemortem diagnosis of meningitis were reviewed. Mean age at admission was 6 days (range, 11 hours to 30 days), and the most common concurrent clinical problem was diarrhea (16/32). Twenty-seven of the calves were available for necropsy. At postmortem, there was evidence of septicemia in 22 (81%) of these calves. Escherichia coli was the organism most frequently isolated (11/16; 69%) from the CNS. The major clinical signs of CNS disturbance observed over the course of hospitalization were lethargy, recumbency, anorexia, loss of suckle reflex, and coma. Leukocytosis and a left shift was evident in 11 of 15 (73%) calves. Concurrent metabolic problems that could have aggravated the CNS disturbance included hyperkalemia and respiratory acidosis. Analysis cerebrospinal of fluid from 22 of the calves, revealed pleocytosis, xanthochromia, turbidity, and high total protein concentration. Cytologically, neutrophils predominated in the CSF in calves with acute disease. Mononuclear cells dominated in calves with chronic disease. Microscopically, bacteria were evident in 10 of 22 (45%) of the antemortem CSF samples and bacteria were isolated from slightly more than half (11/19) of the specimens subjected to microbial culturing. Escherichia coli was the agent most frequently isolated from the CSF. Two of the 9 E coli isolates were resistant to trimethoprim potentiated sulfonamide drugs and all (4/4) of the CSF E coli isolates tested for susceptibility to triple-sulfonamide drugs were resistant. Twenty-seven of the 32 calves died or were euthanatized within 2.43 days after hospitalization.(ABSTRACT TRUNCATED AT 250 WORDS)     

Enzyme-linked immunosorbent assay, using monoclonal antibody, to detect enterotoxic Escherichia coli K99 antigen in feces of dairy calves

A modified, double-antibody, enzyme-linked immunosorbent assay (ELISA) was developed to detect the K99 pilus antigen of enterotoxic Escherichia coli (ETEC) in feces of calves. Extremely high positive to negative ratios (greater than 200) were obtained by using monoclonal antisera as the primary antibody. Strong positive reactions were obtained with strains of E coli known to produce the K99 antigen; however, non-enteropathogenic E coli (strains not producing the K99 antigen), Salmonella, Proteus, Klebsiella, Pseudomonas, Staphylococcus, Streptococcus, and rotavirus produced negative results. Seventy-five fecal samples, 8 from healthy calves and 67 from calves with neonatal calf diarrhea were examined with the K99 ELISA for the presence of ETEC. Rotavirus test and fecal culture results were available on feces from calves with diarrhea and were used with the K99 ELISA results to determine the specific cause of the disease. Enterotoxic E coli was the predominant agent detected in the feces of 29 diarrheal calves less than 5 days of age. Mixed infections of rotavirus and ETEC were also common in these calves, but rotavirus infections alone were not detected. In 38 calves greater than or equal to 5 days, rotavirus was detected without ETEC. Of these calves, only 2 produced positive tests with the K99 ELISA. Salmonella sp and Proteus sp were detected from 5 of 67 calves with diarrhea.     

Occurrence and characteristics of enterohemorrhagic Escherichia coli O26 and O111 in calves associated with diarrhea

The aims of this study were: (1) to examine whether or not enterohemorrhagic Escherichia coli O26 and O111 (EHEC O26 and O111) are involved in neonatal calf diarrhea; (2) to determine the specific age periods at which the calves are vulnerable to these organisms, and (3) to reveal the biochemical, genetic and cytotoxic characteristics of the isolates. The study investigated the occurrence of EHEC O26 and O111 in calves associated with or without diarrhea. A total of 442 diarrheic and non-diarrheic young calves from 115 different farms were examined. Of the 257 calves with diarrhea, 37 (14.4%) and 32 (12.5%) tested positive for EHEC O26 and EHEC O111, respectively. Of the 185 non-diarrheic calves, 14 (7.6%) and 11 (5.9%) tested positive for EHEC O26 and EHEC O111, respectively. EHEC O26 and O111 were recovered from 14/69 (20%) and 11/69 (16%) diarrheic calves <2-weeks-old, respectively, and no EHEC O26 and O111 were detected in the non-diarrheic claves of this age group, suggesting that EHEC O26 and O111 are possible causes of the disease in infected neonatal calves. However, there were similar rates of occurrence in the diarrheic and non-diarrheic calves in the older animals (particularly, aged >10 weeks). PCR analysis showed that the isolates carried various virulence genes such as Ehly, eae, stx1 and stx2, which highlight the potential importance of these attributes for the infection, colonization and the possible pathogenesis of calf diarrhea. Cytotoxicity analysis revealed that many of the EHEC isolates showed high cytotoxicity to Vero cells, re-emphasizing the potential for cattle being a direct source of EHEC infections in humans.     

Bacterial isolates from blood and their susceptibility patterns in critically ill foals: 543 cases (1991-1998)

OBJECTIVE: To assess microorganisms isolated from blood specimens obtained from critically ill neonatal foals and to evaluate their antimicrobial susceptibility patterns. DESIGN: Retrospective study. ANIMALS: 543 neonatal foals. PROCEDURE: Medical records of foals that were < 1 month old and were admitted to a referral neonatal intensive care unit were reviewed for results of bacteriologic culture of blood and antimicrobial susceptibility patterns. RESULTS: At least 1 microorganism was isolated from 155 of 543 (28.5%) foals. Escherichia coli was the most commonly isolated bacterium. A single gram-positive organism was detected in 49 foals. Although 90% of the E coli isolates were susceptible to amikacin, some gram-negative and gram-positive organisms had resistance against multiple antimicrobials. CONCLUSIONS AND CLINICAL RELEVANCE: Gram-negative bacteria remain the most common isolates from blood of neonatal foals; however, gram-positive organisms were also found, and with greater prevalence than reported elsewhere. Susceptibility patterns may vary, and resistance to multiple antimicrobials may develop. This is especially true for organisms such as Enterobacter spp and Enterococcus spp. Prudent empirical treatment for neonatal sepsis should include broad-spectrum antimicrobials.