Capsular type diversity of Mannheimia haemolytica determined by multiplex real-time PCR and indirect hemagglutination in clinical isolates from cattle, sheep, and goats in Spain

This study compares the utility of a commercially available multiplex q-PCR assay for serotyping A1, A2, and A6 M. haemolytica serotypes with indirect hemagglutination, for determining the relative distribution of M. haemolytica capsular types associated with respiratory disorders in cattle, sheep, and goats. For the 129 isolates analyzed, both q-PCR and IHA assays exhibited nearly complete agreement for capsular types A1 (k = 0.965) and A2 (k = 0.888) and substantial agreement for A6 (k = 0.801). Despite the overall good performance of the commercial q-PCR, its effectiveness differed between the host origin of the isolates. The serotype was identified by q-PCR in 83.3 % of cattle, 77.8 % of goat, and 53.8 % of sheep isolates. Combining the results of both methods, A1 was the most prevalent in cattle and sheep (55.6 % and 22.25 %, respectively) but was not detected in goats, A2 was the most prevalent in goats (61.1 %) and the second most prevalent in cattle (16.7 %) and sheep (20.5 %). The prevalence of A6 was 7.4 %, 5.1 %, and 16.7 % in cattle, sheep, and goats, respectively. Other capsular types determined exclusively by IHA were A16 in cattle, A9 in goats, and A7, A8, A9, and A13 in sheep. Capsular type diversity was greater in sheep (H = 0.601) than in cattle (H = 0.408) and goat (H = 0.330) isolates. The commercial multiplex q-PCR is a valuable tool, alternative to IHA, for identifying isolates of capsular types A1, A2, and A6, the most frequent serotypes of M. haemolytica associated with respiratory disease in ruminants. However, when testing sheep isolates it should be complemented with immunological assays due to the wider range of serotypes implicated.

Strength of association between isolation of Pasteurella multocida and consolidation lesions in ovine pneumonic pasteurellosis

This study investigated the association of Pasteurella multocida isolation and the molecular characteristics of the isolates with the presence of pneumonic lesions in lambs at slaughter to assess its importance as a causative agent of pneumonic pasteurellosis compared with Mannheimia haemolytica. P. multocida was isolated from the 13.9% and 2.7%, and M. haemolytica from the 36.4% and 26.8%, of lungs with and without lesions, respectively (P < 0.05). Both microorganisms were frequently coisolated (23.2% and 12.5% from lungs with and without lesions, respectively). Isolation of P. multocida alone exhibited greater strength of association with pneumonic lesions (OR 11.4; 95% CI 3.2-40.6) than that exhibited by M. haemolytica alone (OR 3.0; 95% CI 1.6-5.4). Cluster analysis grouped the lungs into four clusters characterized by the isolation of M. haemolytica or P. multocida alone (clusters 1 and 4), coisolation of both microorganisms (cluster 3), and isolation of neither (cluster 2). Cluster 4 lungs exhibited higher frequencies of pneumonic lesions (87.5%) and severe (20.8%) and moderate (25.0%) lesions. Lungs coinfected with both pathogens (cluster 3) did not exhibit a higher frequency of severe and moderate consolidation lesions (6.1% and 14.3%, respectively), suggesting that P. multocida and M. haemolytica do not act synergically to cause more severe pneumonic infections. The greater strength of association of P. multocida isolation with pneumonic lesions together with the higher severity of the lesions caused could indicate a greater role played by this pathogen in the aetiopathogenesis of pneumonic pasteurellosis in sheep than is commonly assumed.

Pasteurella multocida isolates associated with ovine pneumonia are toxigenic

The P. multocida toxin (PMT), a dermonecrotic protein encoded by the toxA gene, is the major virulence factor of capsular type D P. multocida strains causing progressive atrophic rhinitis (PAR) in pigs. A high frequency of P. multocida isolates harboring the toxA gene has been found among ovine pneumonic isolates, although the ability of these isolates to express PMT has never been examined. In this study we have investigated the ability of ovine toxA+ P. multocida isolates (n = 57) to express a functional toxin by detection of PMT toxin antigen using an ELISA test and its cytopathic effect in a Vero cell assay. PMT antigen was expressed in the great majority (54/57; 94.7%) of toxA+ isolates. Moreover, the 100% toxA+ ovine isolates analyzed produced a cytopathic effect in Vero cells within 24-48 h post-inoculation, identical to that described for porcine toxigenic P. multocida isolates. These results show for the first time that, in addition to isolates associated with PAR, isolates of P. multocida associated with pneumonia in sheep are also toxigenic. In addition, we found a total agreement (Kappa = 1; C.I. 0.75-1.25) between the detection of the toxA gene and the toxigenic capability of P. multocida isolates, indicating the PCR detection of toxA would be a suitable predictive marker of the toxigenic fitness of P. multocida.

Detection of the astA (EAST1) Gene in Attaching and Effacing Escherichia coli from Ruminants

A total of 206 attaching and effacing Escherichia coli strains from ruminants were analysed for the presence of the astA (EAST1) and bfpA genes. None of these strains was bfpA-positive. The percentage of enteropathogenic E. coli (EPEC) strains astA-positive found in healthy cattle (15.6%) suggests that this animal species may be a significant reservoir of atypical EPEC potentially pathogenic for humans.

Typing of the eae and espB genes of attaching and effacing Escherichia coli isolates from ruminants

The types of the eae and espB genes of 178 attaching and effacing Escherichia coli (AEEC) strains isolated from diarrhoeic and healthy ruminants were investigated by PCR. Six types of the eae gene: beta (beta), gamma1 (gamma-1), gamma2 (gamma-2), epsilon (epsilon), zeta (zeta) and iota (iota), and three types of the espB gene: alpha, beta and gamma were identified in the strains studied. Moreover, three strains were negative to all the types of the eae gene tested. The types beta and gamma2 in healthy cattle, beta, gamma2 and epsilon in healthy sheep and goats, and beta in diarrhoeic calves, lambs and goat kids were the most frequent types of the eae gene among the strains studied. Although the eaebeta gene was the most prevalent among AEEC from healthy and diarrhoeic ruminants, the percentages of AEEC strains with this type found in this study in diarrhoeic animals (66.7-100%) were higher than those found in healthy animals (33.3-40.6%). Thus, these data suggest that AEEC strains with the eaebeta gene are associated with neonatal diarrhoea in ruminants. The eaegamma1, eaezeta and eaeiota genes were found in low percentages in the strains studied (4.5, 2.8 and 7.3%, respectively). All the types of the eae gene, except the type iota, showed a close correlation with the types of the espB gene: the eaebeta and eae epsilon genes with the espBbeta gene, the eaegamma2 and eaezeta genes with the espBalpha gene and the eaegamma1 gene with the espBgamma gene.

Prevalence and characterization of Vero cytotoxin-producing Escherichia coli isolated from diarrhoeic and healthy sheep and goats

Faecal samples from 146 diarrhoeic lambs and goat kids, and from 511 healthy sheep and goats were screened for the presence of Vero cytotoxin-producing Escherichia coli (VTEC). In healthy sheep and goats, VTEC were isolated in 24.4 and 16.2% of the animals, respectively. Moreover, VTEC were detected in 3.1 and 5.9% of the diarrhoeic lambs and goat kids, respectively. These data suggest that VTEC seems not to be associated with diarrhoea in lambs and goat kids. Only four VTEC strains were eae-positive. The absence of the eae gene in most of these VTEC strains could indicate that these strains are less virulent for humans that the classical eae-positive enterohaemorrhagic E. coli types. However, almost half (42.9%) and 12.2% of VTEC strains isolated from healthy sheep and goats, respectively, belonged to serotypes associated with severe diseases in humans.

Verotoxin-producing Escherichia coli (VTEC), enteropathogenic E. coli (EPEC) and necrotoxigenic E. coli (NTEC) isolated from healthy cattle in Spain

AIMS

To determine the prevalence and characteristics of verotoxigenic Escherichia coli (VTEC), enteropathogenic E. coli (EPEC) and necrotoxigenic E. coli (NTEC) in healthy cattle.

METHODS AND RESULTS

Faecal samples from 412 healthy cattle were screened for the presence of VTEC, EPEC and NTEC. Four isolates from each sample were studied. VTEC, EPEC and NTEC were isolated in 8.7%, 8.2% and 9.9% of the animals, respectively. VTEC and NTEC were isolated more frequently from calves and heifers than from adults. Seventy (4.2%), 69 (4.2%) and 74 (4.5%) of the 1648 E. coli isolates were VTEC, EPEC and NTEC, respectively. Seventeen (24.3%) of the VTEC strains were eae-positive. Thirty-six (51.4%) of VTEC strains belonged to E. coli serogroups associated with haemorrhagic colitis and haemolytic uraemic syndrome in humans. The serogroups most prevalent among the EPEC strains were O10, O26, O71, O145 and O156.

CONCLUSIONS

Healthy cattle are a reservoir of VTEC, EPEC and NTEC.

SIGNIFICANCE AND IMPACT OF THE STUDY

Although most of the VTEC strains were eae-negative, a high percentage of VTEC strains belonged to serogroups associated with severe disease in humans.

[Mycotic pseudoaneurysm caused by Mycobacterium tuberculosis]

Mycobacterium tuberculosis can involve any organ of the body, including the arteries. Usually the mycobacteria infects the arterial wall spreading from a contiguous foci. We report a case of tuberculous pseudoaneurysm involving the iliac artery clinically manifested as fever of unknown origin. The diagnosis relied on abdominal CT-scanning. Tuberculous etiology was confirmed postoperatively by microbiologic and microscopic study. The antituberculous therapy was early started, but the patient died three months later as a consequence of a non-infectious abdominal aortic rupture. Clinicians should consider tuberculous etiology when the diagnosis of mycotic pseudoaneurysm is being entertained.

Quinolone resistance in potentially pathogenic and non-pathogenic Escherichia coli strains isolated from healthy ruminants

Quinolone resistance was studied in potentially pathogenic and non-pathogenic Escherichia coli strains from healthy ruminants. In cattle, 5.9% of the strains were resistant to nalidixic acid and 4.9% were resistant to enrofloxacin and ciprofloxacin, whereas in sheep and goats only 0.5% and 1.4%, respectively, of the strains were resistant to nalidixic acid and none to fluoroquinolones. Most of the strains resistant to quinolones were non-pathogenic strains isolated from cattle. However, the results of this study do not show that the potentially pathogenic E. coli strains isolated from healthy ruminants are more susceptible to quinolones than the non-pathogenic E. coli strains.

Association between intimin (eae) and EspB gene subtypes in attaching and effacing Escherichia coli strains isolated from diarrhoeic lambs and goat kids

Attaching and effacing Escherichia coli (AEEC) strains isolated from diarrhoeic lambs and goat kids were characterized for intimin (eae) and EspB (espB) gene subtypes by PCR and sequencing, and for genetic relatedness by PFGE. Fifty (23 ovine and 27 caprine) AEEC strains of 398 (246 ovine and 152 caprine) analysed were detected by colony blot hybridization. These strains were epidemiologically unrelated since they were isolated from different outbreaks of neonatal diarrhoea over a long period. Ovine AEEC strains belonged to serogroups O2, O4, O26, O80, O91 or were untypable, and caprine strains belonged to serogroups O3, O153 and O163. Two intimin subtypes were detected among the ovine and caprine strains studied. Most of the strains (43/50) had the beta type intimin gene, but seven ovine strains possessed a variant gamma type intimin gene (gamma(V)). Analysis of deduced amino acid sequences of the eae gene revealed that the sequences of beta intimin of ovine and caprine strains were virtually identical to those of beta intimin of rabbit EPEC, human EPEC clone 2 and swine AEEC, whereas the gamma(V) intimin present in seven ovine strains had 75-76% identity with gamma intimin of human EHEC clone 1 strains, and 96% of identity with intimin of the human EHEC strain 95NR1 of serotype O111:H-. A PCR test was developed to identify the three different espB gene subtypes, espB of human EPEC clone 1 (espBalpha), espB of human EHEC clone 1 (espBgamma) and espB of rabbit EPEC and human EPEC clone 2 (espBbeta). There was close correlation between the intimin beta type and the espBbeta gene subtype in the ovine and caprine AEEC strains. The seven ovine strains possessing the gamma(V) intimin gene possessed the espBalpha gene subtype. None of the strains studied possessed the espBgamma gene found in human O157:H7 EHEC strains. PFGE analysis of genomic DNA of selected strains showed a great diversity among strains. Cluster analysis of PFGE patterns showed greater divergence between strains with the gamma(V) intimin gene than between strains with the beta intimin gene. This study showed that most of the AEEC strains isolated from diarrhoeic lambs and goat kids possessed beta intimin and espB genes identical to those of rabbit EPEC, and they may be associated with enteric disease in small ruminants.

Nosocomial Kikuchi's disease--a search for herpesvirus sequences in lymph node tissues using PCR

BACKGROUND

Histiocytic necrotizing lymphadenitis, also known as Kikuchi's disease (KD), is a rare disease. Fever and lymphadenopathies with characteristic pathologic features are present. The etiology of this disease remains undetermined. Since the disorder is self-limiting, different viruses have been implicated as the causative agent.

PATIENTS AND METHODS

Seven cases of KD were studied. Three patients acquired the disease nosocomially, three had community-acquired KD and one case was associated with systemic lupus erythematosus. PCR was performed on DNA extracted from lymph node tissues in order to detect herpesvirus-specific DNA sequences: herpes simpLex virus type 1 and 2 (HSV1-2), varicella zoster virus (VZV), human cytomegalovirus (HCMV), human herpesvirus 6 (HHV6), Epstein-Barr virus (EBV) and human herpesvirus 8 (HHV8).

RESULTS

Viral DNA was not detected in any of the lymph node tissues from the seven cases of KD.

CONCLUSION

We conclude that these herpesviruses were not involved in the etiology of the three cases of nosocomial KD, nor in the other four cases of KD investigated in this study.

Rotavirus and concurrent infections with other enteropathogens in neonatal diarrheic dairy calves in Spain

Faeces samples from 218, one to 30 days old, diarrheic dairy calves in 65 dairy herds were screened for the presence of rotavirus and concurrent infections with coronavirus, Cryptosporidium, F5+ Escherichia coli and Salmonella spp. Calves were grouped according to their age as follows: 1-7, 8-14, 15-21 and 22-30 days. Rotavirus infection was detected in 46.9%, 45.6%, 33.8% and 48.3% of the calves in the respective age-groups. No significant differences in the detection rate of rotavirus were found among calves on the different age-groups. Rotavirus was the only enteropathogen detected in 39 of the 93 (41.9%) diarrheic calves positive to this agent. Concurrent infections with other enteropathogen(s) were detected in 31.3%, 33.3%, 20.6% and 3.4% of the rotavirus infected calves in the age-groups 1-7, 8-14, 15-21 and 22-30 d, respectively. A significant age-associated decrease in the detection rate of mixed infections (p < 0.01) was found. The detection rates of the other enteropathogens considered in calves with rotavirus infection were 20.4% for coronavirus, 85.2% for Cryptosporidium, 16.7% for F5+ E. coli and 1.8% for Salmonella.

In vitro susceptibility of Escherichia coli strains isolated from diarrhoeic dairy calves to 15 antimicrobial agents

The in vitro activities of 15 antimicrobial agents against 195 strains of Escherichia coli isolated from dairy calves affected by neonatal diarrhoea were determined. Of these strains 137 produced one or more potential virulence factors (F5, F41, F17, cytotoxic necrotizing factor, verotoxin and the eae gene), but the remaining 58 strains did not produce any of these factors. The overall percentage of resistant strains to streptomycin, tylosin and tetracycline was very high (above 65%). A high level of resistance (from 23 to 50%) to ampicillin, neomycin, kanamycin, spectinomycin, chloramphenicol, sulphadimethoxine and trimethoprim was also detected. The E. coli strains were very susceptible (89-95%) to apramycin and gentamicin and highly susceptible (99-100%) to polymyxin B, florfenicol and nitrofurazone. Some significant differences (P < 0.05) in the frequencies of resistance to some of the antimicrobials tested and in the rates of multi-drug resistance among the strains producing potential virulence factors and non-fimbriated, non-toxigenic, eae-negative strains were found. Most of the strains showed multi-resistance: 76.9% of the isolates were resistant to at least two antibiotics, 67.7% were resistant to at least four antibiotics and 50.3% were resistant to at least six antibiotics.

Prevalence and characteristics of necrotoxigenic Escherichia coli (NTEC) strains isolated from diarrhoeic dairy calves

Fecal samples from 246, 1-90-days old diarrhoeic dairy calves in 72 herds were screened for the presence of cytotoxic necrotizing factors (CNF)-producing Escherichia coli (NTEC). NTEC were detected by tissue culture assays and PCR in 39 (15.8%) of the diarrheic calves, and the majority of these animals (34 of 39, ca. 87.2%) were infected by NTEC producing CNF2. Calves were grouped according to their age (1-7 days, 8-14 days, 15-21 days, 22-30 days and 31-90 days) and analyses of prevalence were done by the Mantel-Haenzsel chi2-test for trend. A significant age-associated increase in the prevalence of NTEC producing CNF2 (p<0.0001) was found. Eighty-one (8.4%) of the 958 E. coli isolates from the 246 diarrheic calves were positive for CNF in the tissue culture assays. These strains were analyzed by PCR and this technique showed that three (3.7%) strains were CNF1-positive and 75 (92.6%) were CNF2-positive. Moreover, three of the strains positive in the tissue culture assays were negative by PCR. These strains were subsequently assayed in several biological tests (rabbit skin test, mouse intraperitoneal test and mouse footpad test) which showed that they were really NTEC, probably producing CNF2, but with some different properties to classical strains producing CNF2. NTEC strains producing CNF2 belonged to different serogroups (O2, O7, O9, O14, O15, O41, O43, O45, O55, O76, O86, O88, O109, O115, O123, O128, O153 and O159) than strains producing CNF1 (O11 and O32) or PCR-negative strains (O111). Moreover, a strong association between CNF2 and F17 fimbriae was found (78.6% of CNF2-positive strains were F17-positive, whereas only 22.9% of CNF2-negative strains were F17-positive).

Characterization of nonenterotoxigenic Escherichia coli strains producing F17 fimbriae isolated from diarrheic lambs and goat kids

Forty-five ovine and caprine nonenterotoxigenic Escherichia coli strains producing F17-related fimbriae were characterized with respect to the fimbrial structural subunit and adhesin subtypes produced. In addition, several characteristics related to the virulence of strains producing F17 fimbriae were studied. Most of the strains (73%) possessed the f17cA structural subunit gene, whereas the f17aA and f17dA genes were detected only on three (6%) and two (4%) strains, respectively. The f17bA gene was not detected. All but one of these strains possessed the f17G genes of the adhesin subfamily II. The only strain having the f17G gene of subfamily I possessed the structural subunit gene f17dA. Sequencing of the f17A and f17G genes of four selected strains confirmed the association of f17cA and f17dA structural subunit genes with the f17G genes of the adhesin subfamily II. These results indicated that adhesins of the subfamily II are prominent among ovine and caprine isolates and that they are indistinctly associated with the F17 structural subunit subtypes on these field strains. CS31A- and CNF2-related genes were not detected. Most of the strains adhered in vitro to ovine intestinal brush borders (36 of 45) and agglutinated the erythrocytes of different species in the presence of D-mannose (39 of 45). F17-positive strains produced colicin V (57%) and were resistant to the bactericidal effect of serum (91%) in significantly higher percentages than F17-negative strains (34% produced colicin V, and 66% were serum resistant). Thus, most of the studied ovine and caprine strains showed phenotypic characteristics of septicemic strains.

In vitro activities of cephalosporins and quinolones against Escherichia coli strains isolated from diarrheic dairy calves

The in vitro activities of several cephalosporins and quinolones against 195 strains of Escherichia coli isolated from diary calves affected by neonatal diarrhea were determined. One hundred thirty-seven of these strains produced one or more potential virulence factors (F5, F41, F17, cytotoxic necrotizing factor, verotoxin, and the eae gene), but the remaining 58 strains did not produce any of these factors. From 11 to 18% of the E. coli strains were resistant to cephalothin, nalidixic acid, enoxacin, and enrofloxacin. However, cefuroxime, cefotaxime, and cefquinome were highly effective against the E. coli isolates tested. Some significant differences (P < 0.05) in resistance to quinolones between the strains producing potential virulence factors and nonfimbriated, nontoxigenic, eae-negative strains were found. Thus, eae-positive, necrotoxigenic, and verotoxigenic (except for nalidixic acid) E. coli strains were significantly more sensitive to nalidixic acid, enoxacin, and enrofloxacin than nonfimbriated, nontoxigenic, eae-negative strains. Moreover, eae-positive strains were significantly more sensitive to enoxacin and enrofloxacin than F5-positive strains. Thus, the result of this study suggest that the bovine E. coli strains that produce some potential virulence factors are more sensitive to quinolones than those that do not express these factors.

Cryptosporidium and concurrent infections with other major enterophatogens in 1 to 30-day-old diarrheic dairy calves in central Spain

Faeces samples from 218, 1 to 30-day-old, diarrheic dairy calves in 65 dairy herds were screened for the presence of Cryptosporidium and concurrent infections with rotavirus, coronavirus, F5 Escherichia coli and Salmonella spp. Calves were grouped according to their age as follows: 1-7, 8-14, 15-21 and 22-30 days. Cryptosporidium infection was detected in 43.8%, 71.9%, 63.2% and 6.9% of the calves in the respective age groups. Significant differences in the detection rate of Cryptosporidium were found between the age group 22-30 days and all other age groups, and between the age group 1-7 days and the age groups 8-14 days and 15-21 days. Cryptosporidium was the only enteropathogen detected in 60 of the 114 (52.6%) diarrheic calves. Concurrent infections with other enteropathogen(s) were detected in 64.3%, 46.3%, 39.5% and 0% of the Cryptosporidium-infected calves in the age groups 1-7, 8-14, 15-21 and 22-30 days, respectively. A significant age-associated decrease in the detection rate of mixed infections (p < 0.05) was found. The detection rates of the other enteropathogens considered in calves with Cryptosporidium infection were 87% for rotavirus, 11.1% for coronavirus, 27.8% for F5+ E. coli and 1.8% for Salmonella.

Verotoxin-producing Escherichia coli (VTEC) and eae-positive non-VTEC in 1-30-days-old diarrhoeic dairy calves

Faecal samples from 221, 1-30-days-old, diarrhoeic dairy calves were screened for the presence of verotoxin-producing Escherichia coli (VTEC) and eae-positive non-VTEC. Calves were grouped according to their age (1-7, 8-14, 15-21 and 22-30 days) and analyses of prevalences were done by Mantel-Haenzsel chi 2-test for trend. VTEC and eae-positive non-VTEC were detected in 20 (9.0%) and 18 (8.1%) of the diarrhoeic calves, respectively. A significant age-associated increase in the prevalence of VTEC (p = 0.0001), but not in the prevalence of eae-positive non-VTEC (p = 0.381), was found. Significant differences in VTEC prevalence were found between the age-group 22-30 days and in all other age-groups. 43 (5.0%) of the 861 E. coli isolates from the 221 diarrhoeic calves were VTEC, and 30 (69.8%) of these strains produced VT1 only. More than one-half of the VTEC strains (55.8%) were positive for the eae gene and all these eae-positive VTEC strains produced VT1 only. A high percentage (76.7%) of VTEC strains belonged to E. coli serogroups (O4, O26, O39, O91, O113, O128 and O145) associated with haemorrhagic colitis and haemolytic uraemic syndrome in humans. 51 (5.9%) of the E. coli strains studied were eae-positive non-VTEC and the serogroups most prevalent among these strains were O4, O14, O26 and O123. Only four of the eae-positive strains were also espB-positive by hybridization with a probe from a human EPEC isolate and none of these strains produced VT.

Proportional morbidity rates of enteropathogens among diarrheic dairy calves in central Spain

Faecal samples from 218 diarrheic dairy calves in 65 dairy herds, selected by convenience, were screened for the presence of rotavirus, coronavirus, Cryptosporidium spp., F5+ Escherichia coli and Salmonella spp. Animals surveyed were from 1 to 30 days old. Cryptosporidium and rotavirus were the most commonly detected agents (52.3% and 42.7% of the samples positive, respectively). F5+ E. coli was detected in the faeces of 11.9% of the calves and bovine coronavirus was detected in the faeces of 7.3% of the calves. Salmonella spp. was only found in the faeces of two calves (0.9%). Mixed infections with two or more agents occurred in 28% of the calves. Concurrent infection of rotavirus and Cryptosporidium was found in 21.6% of the calves. Two tests were used for the detection of rotavirus (a commercial ELISA and PAGE), F5+ E. coli (ELISA and bacterial culture) and Cryptosporidium (ELISA and microscopy). The validity of the commercial ELISA for the detection of rotavirus, F5+ E. coli and Cryptosporidium in faeces from diarrheic calves was evaluated using PAGE, bacterial culture and microscopy as gold standard, respectively. The ELISA showed a very low sensitivity (28.6%) for the detection of F5+ E. coli compared to bacterial culture.

Serogroups, toxins and antibiotic resistance of Escherichia coli strains isolated form diarrhoeic goat kids in Spain

Fifty-five Escherichia coli strains isolated from 55 diarrhoeic goat kids from 13 flocks in Spain were serotyped and investigated for production of enterotoxins (LT and STa), verotoxins (VT1 and VT2), cytotoxic necrotizing factors (CNF1 and CNF2), alpha-hemolysin (Hly) and enterohemolysin (EntHly), and for antibiotic resistance. Only 3 (5%) strains were toxigenic: 1 VT1+EntHly+ (serogroup O8) and 2 CNF2+ (both of serogroup O153). The strains serotyped belonged to 19 serogroups. However, 31 (56%) were of one nine serogroups (O3, O8, O9, O10, O11, O21, O44, O103 and O153) and only three of them (O8, O9 and O11) accounted for 29% of the strains. The highest percentages of antibiotic resistance in order of frequency were: streptomycin (93%), sulfadiazine (89%), tetracyline (84%), kanamycin (82%), neomycin (82%) and ampicillin (69%). We conclude that E. coli strains isolated from diarrhoeic goat kids are usually non-toxigenic and belong to a large number of serogroups.

Influence of age of the donor sheep on the phagocytosis of Staphylococcus aureus subspecies anaerobius and S aureus by neutrophils

The age of the sheep donating neutrophils had a marked influence in vitro on their phagocytic ability with respect to Staphylococcus aureus and S aureus subspecies anaerobius. Neutrophils from lambs five to eight weeks old phagocytosed these organisms significantly less efficiently (P < 0.001) than neutrophils from adults two to four years old. However, neutrophils from the young animals phagocytosed S aureus significantly (P < 0.001) better than S aureus subspecies anaerobius (61.5 v 53.8 per cent), whereas there was no significant difference in the ability of the neutrophils from adult sheep to phagocytose S aureus and S aureus subspecies anaerobius (68.2 v 68.2 per cent).

In vitro susceptibility of Escherichia coli strains isolated from diarrhoeic lambs and goat kids to 14 antimicrobial agents

The in vitro activities of 14 anti-microbial agents were determined against 92 strains of E. coli isolated from lambs (60 strains) and kids (32 strains) affected by neonatal diarrhoea. The overall percentage of resistant strains to streptomycin, sulphadimethoxine and tetracycline was very high (above 70%). A high level of resistance (from 30% to 50%) to ampicillin, kanamycin, neomycin and chloramphenicol was also detected. The E. coli strains were highly susceptible to cephalosporins, polymyxin and quinolones. Most of the strains showed multiresistance: 77.2% of isolates were resistant to at least two antibiotics, 55.4% were resistant to at least four antibiotics and 33.7% were resistant to at least six antibiotics. A total of 34 antibiotypes could be distinguished.

Serogroups, toxins and antibiotic resistance of Escherichia coli strains isolated from diarrhoeic lambs in Spain

One hundred and forty-four Escherichia coli strains isolated from 144 diarrhoeic lambs (5 to 21 days old) from 38 flocks in Spain were serotyped and investigated for production of enterotoxins (LT and STa), verotoxins (VT1 and VT2), cytotoxic necrotizing factors (CNF1 and CNF2), alpha-haemolysin (Hly) and enterohaemolysin (EntHly), for necrotic and lethal activities and for antibiotic resistance. The strains belonged to 39 different serogroups; however, 58% were of one of 13 serogroups (O4, O6, O7, O8, O9, O11, O23, O26, O77, O80, O101, O103 and O161) and only four of them (O8, O9, O11 and O77) accounted for 34% of strains. In total 10 (7%) toxigenic strains were detected: two LT+, two VT1+ EntHly+, four VT1+ EntHly-, one CNF1+ Hly+ and one CNF2+. The highest percentages of antibiotic resistance were reached in the group of antibiotics (tetracycline, streptomycin, sulphadiazine, ampicillin, kanamycin, neomycin, chloramphenicol, trimethoprim and cotrimoxazole) that are most generally used by Spanish veterinary clinics. We conclude that E. coli strains isolated from diarrhoeic lambs are not generally toxigenic and belong to a large number of serogroups.

In vitro activity of fifteen antimicrobial agents against methicillin-resistant and methicillin-susceptible Staphylococcus intermedius

In this study the susceptibility of 91 methicillin-resistant and -susceptible Staphylococcus intermedius strains (MRSI and MSSI, respectively) against 15 antimicrobial agents was determined. The activity of the antimicrobial agents was studied at pH 7.2 and pH 8.5. Methicillin was more active at pH 7.2 (28 strains methicillin-resistant) than at pH 8.5 (55 strains methicillin-resistant). Gentamicin showed excellent activity, with only 3 strains resistant at pH 8.5. However, gentamicin would have to be administered parenterally. Oxytetracycline cannot be recommended for treatment of canine staphylococcal dermatitis, due to the high percentage (over 25%) of strains that were found to be resistant. Clindamycin showed little activity in inhibiting growth of the strains studied, the percent resistance at pH 7.2 was 93.4%. Rifampin behaved differently at the two pH values. However, a close relationship was noted between methicillin-resistant and rifampin-resistant strains, particularly at the lower pH. Of the fluoroquinolones, ciprofloxacin or enrofloxacin would be a good useful alternative for the treatment of methicillin-resistant strains of S. intermedius. Lastly, very high resistance to sulphamethoxypyridazine was found, as was the case with trimethoprim and a combination of trimethoprim/sulphamethoxypyridazine, against not only MRSI but also MSSI strains.

Comparative in vitro activity of 11 beta-lactam antibiotics against 91 Staphylococcus intermedius strains isolated from staphylococcal dermatitis in dogs

A study was made of the susceptibility of 91 strains of Staphylococcus intermedius, isolated from staphylococcal dermatitis of dogs, to 11 beta-lactam antimicrobial agents. The activity of these antimicrobial agents against all strains was tested at pH 7.2 and 8.5. Finally, a comparative study was made of the susceptibility of these micro-organisms, dividing them into six groups: beta-lactamase positive and negative, methicillin resistant and susceptible and oxacillin resistant and susceptible. Only three of the 11 antimicrobial agents studied exhibited satisfactory behaviour at the two pH levels studied: mezlocillin, cefazolin and cefalotine. There was a good correlation at pH 8.5 between methicillin-resistant strains and those resistant to penicillin G, ampicillin, amoxycillin, cefamandole and cefuroxime. This correlation was not observed, however, between oxacillin-resistant strains and strains resistant to the other antimicrobial agents studied.

In vitro activities of enoxacin, enrofloxacin, sparfloxacin, and ciprofloxacin against Escherichia coli strains isolated from diarrheic lambs and kids

The in vitro activities of four fluoroquinolone compounds were tested against 92 Escherichia coli strains of ovine and caprine origin under aerobic and anaerobic incubation conditions. The four fluoroquinolones proved to be highly effective against the E. coli isolates tested. When bacteria were cultured anaerobically, at least fourfold increases in the MICs of enoxacin for the strains occurred and no detectable changes in enrofloxacin, sparfloxacin, and ciprofloxacin MICs occurred.

Experimental intramammary infection of ewes with Staphylococcus aureus subsp anaerobius

The susceptibility of the ovine mammary gland to experimental infection with Staphylococcus aureus subsp anaerobius was studied in five lactating Churra ewes. The left mammary gland of each ewe was inoculated with bacteria while the right halves remained untreated and served as a control. A rapid cellular response was elicited in all inoculated glands. The reaction of inoculated mammary glands varied from that of clinical mastitis (ewes C and D) to subclinical mastitis (ewes B and E) or merely to a transient increase of somatic cell counts (ewe A). S aureus subsp anaerobius is less pathogenic for ewes by the intramammary route than S aureus since doses of about 10(8) bacteria caused clinical mastitis in only two of the inoculated animals.

Polyclonal antibodies against Staphylococcus aureus ATCC 12600 catalase do not recognize any protein in cellular extracts from S. aureus subsp. anaerobius

Rabbits were immunized with electrophoretically pure catalase from Staphylococcus aureus ATCC 12 600. The antiserum was used to study whether S. aureus subsp. anaerobius was able to synthesize the apoprotein of catalase. Proteins were separated on polyacrylamide gels (SDS-PAGE) and transferred to nitrocellulose membranes and were detected by immunoblotting. No protein reacting with the purified immunoglobulins against S. aureus ATCC 12,600 catalase could be detected in crude and partially purified cellular extracts from S. aureus subsp. anaerobius or its aerotolerant mutants.

Enterotoxin and toxic shock syndrome toxin-one production by staphylococci isolated from mastitis in sheep

From 160 staphylococci isolated from ovine mastitis, 125 were identified as coagulase-positive staphylococci (CPS) and 35 as coagulase-negative staphylococci (CNS). Of these, 108 (87.8%) S. aureus produced at least one of the staphylococcal enterotoxins (SE) described. However, no CNS was found to be enterotoxigenic. Enterotoxin C (SEC) was the type most frequently produced. TSST-1 was shown to be produced by 91 (74.0%) of S. aureus, almost invariably in combination with SEC. Three CNS strains were also found to produce TSST-1 (two strains of S. xylosus and one strain of S. epidermidis).