International disease surveillance. International disease monitoring, October to December 2004

To assess whether the rates of antimicrobial susceptibility in bacteria isolated from the urine of dogs with urinary tract infections are similar to those of bacteria isolated from bitches with pyometra, the antimicrobial resistance of Escherichia coli isolated from the two groups were determined and compared. The samples were collected in Sweden between April 2002 and March 2003, and potential changes over time were assessed by comparing the results with corresponding data from 1991 to 1993. Among 80 isolates of E coli from cases of pyometra, the proportions that were resistant to the antimicrobials used in canine practice were generally low (ampicillin 10 per cent, enrofloxacin 4 per cent, gentamicin 0 per cent, streptomycin 5 per cent, sulfamethoxazole 8 per cent, tetracycline 4 per cent and trimethoprim 2 per cent) and similar to the proportions reported previously. Significantly lower proportions of resistance were recorded among the pyometra isolates than among 92 isolates from urine samples submitted by animal hospitals to ampicillin (P=0.04), streptomycin (P=0.002) and tetracycline (P=0.03), but there were no differences between the pyometra isolates and 113 isolates from urine samples submitted by animal clinics.     

Phage typing coagulase-positive staphylococci from rooks and gulls

Phage typing was performed on 86 strains of Staphylococcus aureus and 25 strains of Staphylococcus intermedius from rooks and gulls with human, bovine, chicken and canine phages. Eighty per cent of the S aureus strains and 64 per cent of the S intermedius strains were typable. The S aureus biotype D strains of rook origin were specifically lysed at routine test dilution (RTD) by chicken phages from groups I or I + IV, by human phages belonging to groups I and M, and partly by canine phage 58. The other rook and gull S aureus strains did not show characteristic phage patterns. The S intermedius strains isolated from both species of birds could be typed only with canine phages and this correlated with their classification into biotypes. All the biotype 1 strains tested but only two of 12 biotype 2 strains were lysed with canine phages at RTD.     

Antimicrobial susceptibility of Pseudomonas aeruginosa isolates from dogs with otitis externa

Pseudomonas aeruginosa is a common cause of otitis externa in dogs, and treatment of these infections is becoming problematic because of the increasing number of multiresistant strains. The aim of the present study was to compare the in vitro activities of cefepime, ceftazidime, enrofloxacin, ciprofloxacin, gentamicin and ticarcillin/clavulanic acid against 104 strains of P aeruginosa isolated from dogs with otitis externa. Antimicrobial susceptibility and minimum inhibitory concentrations, in μg/ml, were evaluated by the E test (bioMérieux). The most active compound was ceftazidime, with 100 per cent efficiency. The majority of tested strains were susceptible to ticarcillin/clavulanic acid (89.4 per cent), followed by ciprofloxacin (88.5 per cent) and cefepime (60.6 per cent). The highest resistance was observed to enrofloxacin (51.9 per cent) and gentamicin (43.3 per cent). Large numbers of strains were intermediately susceptible to antibiotics registered for use in veterinary medicine in Croatia--enrofloxacin (47.1 per cent) and gentamicin (41.3 per cent).     

An investigation into the prevalence of S aureus on avian feet.

The feet of 63 domestic poultry and 37 birds of prey were swabbed and cultured. Staphylococcus aureus was isolated from 4 X 7 per cent of the former and 10 X 8 per cent of the latter. The recovery of S epidermidis was considerably higher, the organism being cultured from 80 X 9 per cent of poultry and 62 X 1 per cent of birds of prey. The significance of the low S aureus isolation rates is discussed in relation to avian staphylococcal infections and attention is drawn to the importance of the choice of plasma for the coagulase test when identifying S aureus from non-human sources.     

Biochemical properties and differentiation of coagulase-positive staphylococci from rooks and gulls

Coagulase-positive staphylococci were found in the throats of 46 rooks (69 per cent) and 47 gulls (21 per cent) out of totals of 67 and 229 birds, respectively. Of 111 strains isolated from throat swabs 86 (77.5 per cent) were classified as Staphylococcus aureus and 25 strains (22.5 per cent) as Staphylococcus intermedius. Of the S aureus strains 82 per cent from rooks and 50 per cent from gulls were biotyped. Most of them were identified as biotypes D and B, only a few as biotype A, and none as biotype C. Moreover, among the 24 S intermedius strains (96 per cent) biotypes 1 and 2 could be differentiated according to the type of growth on crystal violet agar and their ability to produce acetoin and acid from maltose, mannitol and trehalose.     

Prevalence of Salmonella serotypes in male mule ducks in Belgium

Salmonella species infections of male mule ducks were studied for 32 months in 100 flocks on nine duck farms in Belgium. The prevalence of Salmonella species infections changed significantly over time (P<0.001) with infection rates of 50, 13.4, 6.7, 2.6 and 2.9 per cent, respectively, at the time of arrival on the farm, at three, six and nine weeks of age, and when the ducks left the breeding unit to enter the force-feeding rooms (at 11 or 12 weeks of age). During the study period, 95 strains of Salmonella were isolated, belonging to 11 serotypes. S Indiana (42.1 per cent) and S Regent (36.8 per cent) were the two most common serotypes, whereas S Typhimurium and S Enteritidis were found only once (1.1 per cent). All isolated strains were resistant to at least two antimicrobials, but resistance to more than five antimicrobials was observed in 21.6 per cent of the strains.     

International dissemination of a high virulence rabbit Staphylococcus aureus clone

High virulence rabbit Staphylococcus aureus strains cause chronic and spreading problems of mastitis, pododermatitis and subcutaneous abscesses on rabbit flock level, whereas infections with low virulence strains are limited to individual rabbits. In the present report, 13 high virulence rabbit S. aureus strains, selected out of a large collection of strains isolated in five European countries between 1983 and 2004, were genotyped using pulsed-field gel electrophoresis, spa typing, multilocus sequence typing (MLST) and accessory gene regulator (agr) group typing. Two low virulence rabbit S. aureus strains were also included in the study. The results indicate the clonal origin of high virulence rabbit S. aureus strains present in Europe. Furthermore, the results of MLST and spa typing form a basis for international epidemiology of rabbit S. aureus strains, as these DNA sequence-based typing techniques can easily be used for intercentre comparisons.     

Immunosuppression in bitches with pyometra

The function of the immune system was studied in 34 bitches affected by pyometra. The mean age of the animals was 8.1 +/- 2.8 years. Samples of peripheral blood were examined using a battery of immunological tests. Data obtained from four sets of animals, grouped according to the severity of their disease, were compared. Leucocytosis (neutrophilia and partial monocytosis) and lymphopenia were detected in 62 per cent and 35 per cent of the bitches, respectively. The increase in the number of leucocytes was higher in the severely affected bitches. Inhibition of mitogen-driven lymphocyte proliferation was the characteristic feature of the immunological profile in bitches affected by pyometra, and this corresponded with the impairment of the general state of health. Sera from bitches showing functional inhibition of lymphocytes suppressed the activity of lymphocytes isolated from normal dogs. Sera from bitches affected by pyometra also had higher levels of immunoglobulins, lysozyme and circulating immune complexes. It can be concluded that pyometra is associated with an inflammatory response, but also with a marked suppression of immune system activity.     

Epizootiology of Salmonella typhimurium infection in chickens]

The incidence of S. typhimurium infections among fowl increased in thr region of Potsdam in general, and on various big farms in particular, 1976 and over the first half of 1977. The outbreaks included subclinical infections and clinically manifest diseases which caused remarkable loss of broilers from the affected stocks (up to 15.92 per cent). Parent stocks contaminated with S. typhimurium were to be the sources of infection in all cases. A total of 1,220 Salmonella strains were isolated from fowl and its environment, with 1,151 of them being S. typhimurium (2.98 per cent of all samples tested). The following amounts of S. typhimurium strains were isolated from different types of samples which had been collected from infected broiler stocks: 8.10 per cent from dead broilers, 5.86 per cent from dead broiler parents, 2.11 per cent from pulp linings of transport cages for day-old chicks, 1.23 per cent from litter, 1.0 per cent from hatching material (eggs or dead and jammed embryos, and 0.12 per cent from swabs used in hygiene supervision). No Salmonellae were isolated from feedstuff. The transmission of S. typhimurium, therefore, is though to have taken the route via the hatching egg and via congenitally infected chicks traded between breeders and propagation farms. The control and prophylaxis of S. typhimurium infections, therefore, should be based primarily on action in the centralised breeding stocks. Specific steps of such action are proposed. Fifty-three strains were biochemically and lysotypically analysed, with the following types being determined: ut/Ph 30 BT b, ut/Ph 30 BT c, n.c. 1/72/n.c. BT b, 2 n.c. BT a, and 1A/6 BT a. The first two types covered 84.9 per cent of all strains isolated from the fowl. All lysotype ut/Ph 30 strains isolated from fowl fell under the copenhagen variant which had rarely been isolated from man in the past. These results are likely to support the demand for a joint control programme for enteritis Salmonellae, with particular emphasis on S. typhimurium, for implementation in human and veterinary medicine.     

Uropathogenic virulence factors in isolates of Escherichia coli from clinical cases of canine pyometra and feces of healthy bitches

Escherichia coli is commonly isolated in canine pyometra, but little is known of the virulence factors that may be involved in the precipitation of this disease. The aim of this study was to compare the prevalence of uropathogenic virulence factor (UVF) genes in E. coli isolates from canine pyometra and from feces of healthy bitches to evaluate their role in the pathogenesis of pyometra. E. coli from 23 cases of canine pyometra and from the feces of 24 healthy bitches were analyzed, by polymerase chain reaction, for UVF genes associated with canine and human urinary tract infections (UTIs). The prevalences of UVFs in E. coli from canine pyometra were similar to that in canine and human uropathogenic E. coli. The prevalence of pap was greater (P=0.036) for E. coli from pyometra (52%) than for fecal isolates (21%), and the papGIII allele was present in all pap-containing isolates. The prevalences of genes for alpha-haemolysin and cytotoxic necrotising factor 1 were not significantly higher (P=0.075) in E. coli from pyometra than from feces. The proportion of pyometra strains with >or=3 UVFs was higher (P=0.039) than that of fecal strains, suggesting that possession of >or=3 UVF genes enhances the pathogenicity of the strain. Our findings demonstrate that E. coli associated with canine pyometra are similar to uropathogenic strains, and that operons that encode P fimbriae, alpha-haemolysin and cytotoxic necrotising factor 1 probably enhance the virulence and pathogenicity of the strain in the canine genital tract.     

Comparative efficacy of three antibiotic products for the treatment and prevention of subclinical mastitis during the dry period

The comparative efficacy of a product containing 500 mg benzathine cloxacillin (Orbenin D.C.). another product containing 100 mg nafcillin, 300 mg procaine benzylpenicillin and 100 mg dihydrostreptomycin (Nafpenzal D.C.) and a third product containing 250 mg cephalonium (Cepravin D.C.), in the elimination and prevention of mastitis due to gram-positive microorganisms during the dry period was investigated in 1253 cows located in 14 herds in Isra?l. Although more uniform results were observed after treatment with Nafpenzal D.C. differences among herds were rather large. The mean cure rate for Staphylococcus aureus quarter infections was 81.4 per cent. New S. aureus infections which occurred between drying off and post calving sampling time were found in 7.0 per cent of the quarters. Dry period therapy reduced infection level with S. aureus from 13.5 per cent of quarters to 8.0 per cent. A similar proportional decrease was found in infection level due to non-agalactiae Streptococcus quarter infections.     

The use of a new phage set for typing poultry strains of Staphylococcus aureus obtained from seven countries

1. Eighty per cent of poultry strains of Staphylococcus aureus tested from French, Belgian, English, West German, Japanese and Argentinian sources were typable using a set of typing phages isolated in this laboratory. Strains from Bulgaria, however, with few exceptions were not typable with this phage set. 2. Strains isolated from lesions generally resembled those from apparently healthy poultry. 3. The existence of two distinct Staph. aureus biotypes on poultry was confirmed by isolates from six of the countries; one of these biotypes closely resembled Staph. aureus variety gallinae as described by Witte et al. (1977).     

Survey of marbofloxacin susceptibility of bacteria isolated from cattle with respiratory disease and mastitis in Europe

A monitoring programme conducted in Europe since 1994 to survey the marbofloxacin susceptibility of bacterial pathogens isolated from cattle has established the susceptibility of bacterial strains isolated before any antibiotic treatment from bovine mastitis and bovine respiratory disease (BRD) cases between 2002 and 2008. Minimum inhibitory concentration (MIC) was determined by a standardised microdilution technique. For respiratory pathogens, Pasteurella multocida and Mannheimia haemolytica isolates (751 and 514 strains, respectively) were highly susceptible to marbofloxacin (MIC≤0.03 μg/ml for 77.39 per cent of the strains) and only 1.75 per cent of M haemolytica strains were resistant (MIC≥4 μg/ml). Histophilus somni isolates (73 strains) were highly susceptible to marbofloxacin (0.008 to 0.06 μg/ml). Mycoplasma bovis MIC (171 strains) ranged from 0.5 to 4 μg/ml. For mastitis pathogens, the majority of Escherichia coli isolates were highly susceptible to marbofloxacin (95.8 per cent of 617 strains). Staphylococcus aureus and coagulase-negative staphylococci (568 and 280 strains) had a homogenous population with MIC centred on 0.25 μg/ml. Streptococcus uberis and Streptococcus dysgalactiae (660 and 217 strains) were moderately susceptible with MIC centred on 1 μg/ml. Marbofloxacin MIC for these various pathogens appeared stable over the seven years of the monitoring programme and was similar to previously published MIC results.     

Studies of necrotizing enteritis of suckling piglets (Clostridium perfringens type C enterotoxemia) in industrialized sow breeding units. 4. Epizootiology]

Necrotising enteritis had been the cause of death of 4.9 per cent in 5,177 nursed piglets, which was established by pathological examination. The number of piglets, in that context, which had come from industrialised sow breeding units was equivalent to 92 per cent. The nursed piglet held the third position, next to smaller ruminants (19.4 per cent) and fowl (6.0 per cent), with regard to the occurrence of Clostridium perfringens enterotoxemia or necrotising enteritis in 112,218 animals which were pathologically examined after death. Necrotising enteritis so far has been rare in the GDR. No regional accumulation has been observed. Several outbreaks on industrialised sow breeding units actually remained stationary. The occurrence of the disease may be favoured by a number of factors which are conducive to accumulation of Clostridium perfringens Type C in a given stock. Group keeping of pregnant sows, simultaneous farrowing of larger groups of sows, group treatment of nursed piglets, using neomycin, chloramphenicol, oxytetracycline, and other antibiotics to which Clostridium perfringens is primarily resistant or has acquired resistance in the course of time are some of those contributive factors. Transmission of Clostridium perfringens Type C through feedstuff is possible, though it would lead to a real outbreak only by high intensity of the contamination, and it played a minor role in proliferation of the disease. 3479 Clostridium perfringens strains were isolated from 9,481 animals, both clinically intact and after death, with 30 species being included. Type classification revealed 2454 strains of Type A (70 per cent), 204 of Type D (5.88 per cent), 164 of Type C (four per cent), and 48 of Type B (1.34 per cent). There were 688 atoxic strains (17 per cent). Swine is the major carrier of Clostridium perfringens Type C, with 87 per cent of all Clostridium perfringens Type C strains having been isolated from swine. Swine was followed by fowl (four per cent), sheep (four per cent), cattle, rabbit, and dog (1.27 per cent each). Clostridium perfringens Type C was obtained from the faeces of clinically intact sows in seven instances, including two cases with sows (0.46 per cent) from farms with no previous record of necrotising enteritis.     

Comparative efficacy of three antibiotic products for the treatment and prevention of sub‐clinical mastitis during the dry period

Summary

The comparative efficacy of a product containing 500 mg benzathine cloxacillin (Orbenin D.C.), another product containing 100 mg nafcillin, 300 mg procaine benzylpenicillin and 100 mg dihydrostreptomycin (Nafpenzal D.C.) and a third product containing 250 mg cephalonium (Cepravin D. C.), in the elimination and prevention of mastitis due to gram‐positive microorganisms during the dry period was investigated in 1253 cows located in 14 herds in Israël.

Although more uniform results were observed after treatment with Nafpenzal D.C., differences were not found among the products with respect to the overall efficacy but differences among herds were rather large. The mean cure rate for Staphylococcus aureus quarter infections was 81.4 per cent. New S. aureus infections which occurred between drying off and post calving sampling time were found in 7.0 per cent of the quarters.

Dry period therapy reduced infection level with S. aureus from 13.5 per cent of quarters to 8.0 per cent. A similar proportional decrease was found in infection level due to non‐agalactiae Streptococcus quarter infections.     

Conjunctival flora observed in 70 healthy domestic rabbits (Oryctolagus cuniculus)

Conjunctival swabs were taken from both eyes of 70 healthy domestic rabbits and cultured to determine the microbial population. Bacteria were recovered from 83 per cent of the specimens. DNase-negative Staphylococcus species (57 per cent) were the most commonly recovered organisms followed by Micrococcus species (25 per cent) and Bacillus species (19 per cent). Other organisms isolated included Stomatococcus species (8 per cent), Neisseria species (8 per cent), Pasteurella species (6 per cent), Corynebacterium species (6 per cent), Streptococcus species (6 per cent) and Moraxella species (4 per cent), and other bacteria were isolated less frequently. Statistical analysis showed that there appeared to be no significant difference between the bacterial isolation rates from different breeds of rabbit. Significantly more of the swabs taken from young rabbits yielded cultivable bacteria than did those taken from rabbits over 12 months of age.     

Incidence of clinical mastitis on farms with low somatic cell counts in bulk milk

A total of 1140 clinical cases of mastitis, with at least one inflamed quarter, were reported on 125 farms with somatic cell counts in bulk milk less than 150,000/ml. The average annual incidence was 17.9 cases per 100 cows and ranged from none to 80 cases per 100 cows. The microorganisms most frequently isolated were Escherichia coli (16.2 per cent), coagulase negative staphylococci (13.0 per cent), Staphylococcus aureus (9.6 per cent) and Streptococcus uberis (8.0 per cent). Only two cases of Streptococcus agalactiae were found. As the incidence of clinical mastitis increased, the proportion of S aureus also increased, while the proportions of E coli, S uberis and Streptococcus dysgalactiae remained about the same. Most of the clinical cases of mastitis occurred in early lactation, in November, December and January. However, after correction for the number of calvings per month, the incidence of mastitis was highest in the early summer months.     

Treatment of persistent intramammary infections with Streptococcus uberis in dairy cows

A survey was conducted of the prevalence of environmental pathogens, especially Streptococcus uberis, as causes of clinical mastitis in dairy cows. The response of intramammary infections with S uberis to conventional treatment was monitored by taking milk samples for bacteriology and somatic cell counting seven, 14 and 21 days after the treatment. The results showed that 51 per cent of the infections failed to respond, and the odds of cases failing to respond was significantly increased when the individual quarter somatic cell count seven days after the treatment was greater than 201,000 cells/ml. Ninety-six per cent of the suspected S uberis isolates identified by culture were confirmed as S uberis by using the api 20 Strep system. Restriction endonuclease fingerprinting was used to type the strains of S uberis isolated from 75 milk samples from 32 cows. Analysis showed that 96 per cent of the cases of S uberis that failed to respond to conventional treatment were persistent infections with one strain rather than reinfections with different strains. The persistent cases of S uberis were treated further with an extended course of intramammary preparations containing either procaine penicillin with dihydrostreptomycin or cefquinome. There was no significant difference between the cure rates achieved by the two preparations, and 55 per cent of the cases that had failed to respond to conventional treatment responded to the additional treatment.     

Virulence factors in Escherichia coli strains isolated from urinary tract infection and pyometra cases and from feces of healthy dogs

The aim of this study was to compare the prevalence of virulence genes in 158 Escherichia coli strains isolated from 51 clinical cases of UTIs, 52 of pyometra and from 55 fecal samples from healthy dogs by PCR. papC was found in 12 (23.5%) strains isolated from UTIs, 19 (36.5%) from pyometra and 10 (18.2%) from feces. papGII was observed in 3 (5.8%) strains from pyometra, and papGIII in 10 (19.6%) from UTIs, 15 (28.8%) from pyometra and 9 (16.4%) from feces. sfaS was detected in 22 (43.1%) strains from UTIs, 24 (46.1%) from pyometra and 19 (34.5%) from feces. hlyA was observed in 17 (33.3%) strains from UTIs, 18 (34.6%) from pyometra and 7 (12.7%) from feces, while cnf-1 was detected in 11 (21.6%) from UTIs, 21 (40.4%) from pyometra and 9 (16.4%) from feces. iucD was observed in 12 (23.5%) strains from UTIs, 9 (17.3%) from pyometra and 1 (1.8%) from feces. usp was found 17 (33.3%) isolates from UTIs and 36 (69.9%) from pyometra.     

Reinfection of bovine mammary glands following dry-cow antibiotic therapy

Dry-cow antibiotic therapy (DCT) was administered to quarters with Staphylococcus aureus or streptococcal infections and the quarters were closely monitored for the presence of new or reactivated mammary infections throughout the dry period and the following lactation. Strains of S. aureus were characterized using a selection of biotyping tests to allow a comparison of S. aureus strains isolated before and after DCT. Cows with 3-4 quarters infected prior to DCT had a high susceptibility to reinfection in the following year. In contrast, for cows with 1-2 quarters infected prior to DCT and for heifers with no previous history of infection, the susceptibility to reinfection or new infection was very low. The majority of the S. aureus infections appearing in the lactation following DCT were due to S. aureus strains which differed from strains isolated prior to DCT, suggesting that these were new infections. Histopathological examination of quarters which had had recurrent S. aureus infections revealed lesions typical of chronic S. aureus mastitis, including extensive lobular fibrosis and atrophy.