Evaluation and use of a nested polymerase chain reaction assay in cats experimentally infected with Bartonella henselae genotype I and Bartonella henselae genotype II.

Cats have been shown to be infected with Bartonella henselae genotype I, B. henselae genotype II, and B. clarridgeiae. Feline bartonellosis infections and the strains involved in these infections are important in both veterinary and human medicine. Nucleic acid amplification methods such as polymerase chain reaction (PCR) are being used in both research and diagnostics as tools for understanding many infectious diseases. Bartonella bacteremia in cats is detected by blood culture; however, because of the limitations of culture (delayed turnaround time and sensitivity limits), PCR may be a more efficient method for identifying infected cats. Three distinct PCR assays that could differentiate among B. henselae genotype I, B. henselae genotype II. and B. clarridgeiae were developed and used to detect as few as 3.2 organisms. Fourteen cats experimentally infected with B. henselae genotype I and B. henselae genotype II were followed by bacterial culture and PCR through the course of infection, including periods of primary and relapsing bacteremia. The PCR assay was positive in 11 of the 14 cats for periods of 1-9 weeks after culture became negative. Of the 223 blood specimens that were culture negative, the PCR assay was positive in 38 (17%) of the specimens. Two of the 14 cats developed relapsing bacteremia. The 2 B. henselae genotypes were amplified in the cats and the bacteremic phase of these infections as determined by PCR lasted for a longer period than previously determined by culture. Using laboratory assays such as PCR to understand the strains involved in feline bartonellosis and the course of the infection is important in the understanding of these zoonotic agents.

Arthrotomy versus arthroscopy and partial synovectomy for treatment of experimentally induced infectious arthritis in horses.

To evaluate the clinical, laboratory, and histologic effects of 2 methods of treatment for infectious arthritis in horses, Staphylococcus aureus (3.4 to 3.9 x 10(3) colony-forming units) was inoculated into the tarsocrural joints of 8 horses on day 0. Each horse was treated with phenylbutazone (2 g, PO, q 24 h) and gentamicin sulfate (2.2 mg/kg of body weight, IV, q 8 h) for 14 days. On day 2, general anesthesia was induced, and each horse had 1 tarsocrural joint treated by arthrotomy, with removal of accessible fibrin and lavage with 3 L of sterile balanced electrolyte solution. An indwelling plastic drain was placed in the standing horse to provide a means for lavage with 3 L of balanced electrolyte solution twice daily for 72 hours. The contralateral tarsocrural joint was treated via arthroscopic debridement, synovectomy, and lavage with 3 L of balanced electrolyte solution. Arthrotomy and arthroscopic portals were allowed to heal by second intention. Lameness and thermographic examinations, analysis and bacteriologic culture of synovia, CBC, and WBC differential count were performed prior to inoculation and on days 1, 3, 6, 8, and 13. On day 14, each horse was euthanatized, and the joints were measured, opened, and photographed. Synovium and articular cartilage were obtained for semiquantitative histologic (H&E stain) and histochemical (safranin O fast green stain) evaluation. Lameness and joint circumference were significantly (P less than 0.05) greater in limbs treated by arthroscopy, synovectomy, and lavage. Arthrotomy with lavage eliminated the S aureus infection significantly (P less than 0.05) earlier than arthroscopy, synovectomy, and lavage, however, both treatments eliminated the infection in all but a single joint.(ABSTRACT TRUNCATED AT 250 WORDS)

Temporal study of staphylococcal species on healthy dogs.

During a 1-year period, specimens were obtained monthly from 5 hair coat and 7 mucous membrane sites of 11 healthy dogs. Among 804 isolates of staphylococci, 13 species were identified. Staphylococcus intermedius was the most frequently isolated (40.2% of total isolates) coagulase-positive species, and S xylosus was the most frequently isolated (17.3%) coagulase-negative species. Moreover, S intermedius was the most frequently isolated species from the 12 sites evaluated and was isolated persistently from 8 of the 9 dogs that completed the 1-year study. On the basis of a commercial identification system, 14 profile numbers were identified for isolates of S intermedius. However, 2 profile numbers accounted for a majority (70.9%) of the isolates. Specific S intermedius biotypes identified on the basis of hemolysis, coagulase production, beta-lactamase activity, and antimicrobial susceptibility patterns were found repeatedly in 3 dogs. Seemingly, S intermedius was a resident of the normal bacterial microflora of these dogs; however, the inability to isolate S intermedius from 1 dog during the study year indicated that not all dogs harbor S intermedius as a resident microorganism.

Survival of a dog with pneumonia caused by Mycobacterium fortuitum.

Pneumonia caused by Mycobacterium fortuitum was diagnosed in the left lung lobes of a 3-year-old male Samoyed. Unilateral pneumonectomy and antibiotic treatment (primarily amoxicillin trihydrate-clavulanate potassium and kanamycin) were associated with resolution of the pneumonia. In dogs, M fortuitum causes pulmonary disease that radiographically resembles bacterial pneumonia. Therefore, M fortuitum infection should be considered in dogs with radiographic signs of bronchopneumonia that worsen despite antibiotic treatment.

Comparison of single-dose and conventional trimethoprim-sulfadiazine therapy in experimental Staphylococcus intermedius cystitis in the female dog.

Cystitis was produced in 4 groups of 6 female dogs each, using salicylic acid, ethanol, and Staphylococcus intermedius. Group-I dogs served as nontreated controls. Starting 2 days after infection was induced, group-II dogs were treated with trimethoprim-sulfadiazine at a dosage of 15 mg/kg given orally 2 times a day for 21 days; groups-III and -IV dogs were treated with single oral dosages of the antibiotic at 60 mg/kg and 90 mg/kg, respectively. Group-I dogs (controls) remained infected for the 26-day duration of the study. The response to therapy seen in group-II dogs was better than the therapeutic responses in groups-III and -IV dogs (P less than 0.05). Results of the present study do not support the efficacy of single-dose therapy for this model of cystitis.

Protein A in Staphylococcus intermedius isolates from dogs and cats.

The presence and quantity of extracellular and cell-bound protein A of Staphylococcus intermedius isolates from dogs and cats were determined, using an enzyme-linked immunoglobulin-binding assay. Horseradish peroxidase-conjugated rabbit anti-bovine immunoglobulin G purified by affinity chromatography was reacted with whole cell and supernatant fractions of S intermedius (n = 139), a protein A-producing strain of S aureus, and a protein A-deficient strain of S epidermidis. Extracellular protein A was found in 118 (84.9%) of 139 isolates of S intermedius. Most (69/118; 58.5%) of these isolates produced greater than 0.2 micrograms of extracellular protein A/ml. Cell-bound protein A was found in 6 (4.3%) of 139 isolates. Only 1 of these isolates contained cell-bound protein A exclusively. The other 5 isolates produced significantly greater amounts of extracellular protein A than cell-bound protein A. Additionally, greater than 96% of extracellular protein A could be removed from supernatants by adsorption with agarose gel containing immunoglobulin G.

Growth of gram-positive mastogenic bacteria in normal, simulated bulk tank, and mastitic milk held at simulated fluctuating temperatures of farm bulk tank.

Growth of Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus agalactiae, Streptococcus dysgalactiae, Streptococcus bovis, and Streptococcus uberis was studied in normal milk, simulated bulk tank milk, and aseptic mastitic milk held at simulated fluctuating temperatures of farm bulk tank for 48 h. With the exception of S. bovis, growth rates of the other five bacteria were similar in both normal and simulated bulk tank milk. Mastitic milk inhibited growth of all bacteria studied. A 24-h adjustment period occurred before most of the bacteria started growing. The mastitis level in a dairy herd may be monitored by cultures of bulk tank milk samples and by calculations as discussed in this study.

Diskospondylitis in a kennel of dogs: clinicopathologic findings.

Selected aspects pertaining to the cause and pathogenesis of diskospondylitis were investigated in a kennel of 45 Airedale Terriers. Diskospondylitis was detected via spinal radiography in 17 male and 14 female dogs. Bacteria isolated from the coat, vagina, and urine of affected Airedales were not statistically different from those isolated from clinically normal Airedales. Serologic evidence of Brucella canis infection was not detected. There was no difference in response to thyrotropin stimulation tests between affected and clinically normal dogs. Necropsy findings in affected dogs included hypercellular renal glomeruli and pulmonary arterial thrombi.

Distribution of staphylococcal species on clinically healthy cats.

Among 827 isolates derived from 113 clinically healthy cats, 12 species of staphylococci were identified. Staphylococci were isolated from each cat and from 54.9% of the anatomic sites evaluated. A mode of 6 (range = 2 to 11) of the 11 anatomic sites evaluated per cat yielded staphylococci. A mode of 8 (range = 2 to 12) isolates were found per cat. Staphylococcus simulans was the most isolated (43.9% of total) coagulase-negative species. Moreover, S simulans was the most isolated species from each of the 11 sites evaluated and, except for the mouth and haircoat, comprised greater than 50% of the isolates from each site. Staphylococcus intermedius was the most isolated (13.5% of the total) coagulase-positive species. Three other species (S epidermidis, S xylosus, and S aureus) comprised 32.2% of the isolates, and 7 species (S haemolyticus, S hominis, S hyicus, S capitis, S warneri, and S saprophyticus) comprised 10.4% of the isolates. Six species (S intermedius [96 of 112 isolates], S haemolyticus [20 of 22], S sciuri [17 of 18], S warneri [10 of 13], S hyicus [10 of 10], and S capitis [7 of 8]) were isolated primarily from household cats. Only 1 species, S xylosus (75 of 87), was isolated primarily from cattery cats. Haircoat specimens (n = 452) yielded 508 isolates (61.4% of the total) distributed among all 12 staphylococcal species and included greater than 50% of the isolates of all species other than S simulans and S sciuri. A more heterogeneous population of staphylococci was isolated from household cats than was isolated from cattery cats.

Comparison of coagulase test methods for identification of Staphylococcus intermedius from dogs.

Staphylococcus intermedius isolates from dogs were tested for coagulase activity by 6 commercial methods and by conventional methods, using rabbit and dog plasma. When compared with the conventional tube method using rabbit plasma, none of the 6 commercial methods was suitable for identification of S intermedius, although the 6 tests performed well using strains of S aureus. Use of rabbit plasma identified more S intermedius isolates than did use of dog plasma.

Detection of beta-lactamase produced by Staphylococcus intermedius.

One iodometric, 2 chromogenic, and 3 acidometric methods were compared for the detection of beta-lactamase produced by Staphylococcus intermedius (n = 105) isolated from dogs. Of 575 tests performed, using the 6 methods evaluated, 316 (55.0%) were positive for beta-lactamase production. The iodometric method was the reference method. With the exception of a high correlation (r = 0.962) between 1 acidometric method and 1 chromogenic method, the 5 commercial methods had correlation coefficients less than 0.900 when comparisons were made among them. The 6 methods were in agreement for 69 (65.7%) of the isolates. Based on the findings of this study, an inexpensive, laboratory-prepared, paper strip iodometric method was as reliable as 5 commercial methods for beta-lactamase detection and is recommended for routine use in clinical laboratories.

Screening for neonatal isohemolytic anemia in calves.

Anti-erythrocytic immunoglobulins in serum and colostrum of 124 anaplasmosis-vaccinated cows were detected with a saline agglutination test. Positive results were correlated with the occurrence of neonatal isohemolytic anemia (NIA) in calves and were used to predict the occurrence of NIA. The disease was prevented by withholding colostrum from calves with a high potential for NIA.

Comparative evaluation of a commercial microdilution method and a conventional disk diffusion method for determination of antibiograms of gram-positive cocci.

A commercial broth microdilution system for testing the antimicrobial susceptibility of gram-positive cocci was compared with the standardized disk agar-diffusion method by testing 254 clinical strains of staphylococci and streptococci using both methods. A total of 2,794 parallel determinations were made with 92.3% complete agreement between the 2 methods; of the discrepancies encountered, 3.0% were minor, 2.5% were major, and 2.1% were very major. The results indicate that the commercial microdilution system may provide a reliable quantitative method for antimicrobial susceptibility testing of clinical isolates from animals.

Effect of beta-lactamase of Staphylococcus intermedius on disk agar diffusion susceptibility tests.

Clinical strains of canine Staphylococcus intermedius (n = 120) were tested for susceptibility to beta-lactam antimicrobics (n = 6) by the standardized disk agar diffusion method and for beta-lactamase (BL) production. Significant differences between susceptibilities for BL producing (n = 68) and non-producing (n = 52) strains were found for penicillin G and ampicillin. Zone sizes of BL producing strains were significantly smaller than those of non-producers for penicillin G, ampicillin, cephalothin, carbenicillin and amoxicillin-clavulanic acid but not for methicillin. However, all strains were sensitive to cephalothin and amoxicillin-clavulanic acid; only one strain was resistant to methicillin; and one strain was intermediate in susceptibility to carbenicillin. Although 62 (52%) strains were sensitive to penicillin G and ampicillin based on established zone size interpretive criteria, 15 (24%) of these strains produced BL. Zone size measurements obtained with beta-lactam antimicrobics that are highly susceptible to inactivation by BL are not reliable and should be disregarded for canine S. intermedius which produce BL.

Antimicrobial susceptibility of coagulase-positive staphylococci isolated from Louisiana dogs.

Disk diffusion susceptibility tests were done on 1,178 clinical strains of coagulase-positive staphylococci (CPS) isolated from dogs during a 7-year period. Relative decreases of 7% to 33% were found in the percentages of CPS sensitive to 8 antimicrobics. Relative percentages of CPS sensitive to 9 other antimicrobics were increased or decreased less than 5%. Sensitivity to the beta-lactam antibiotics showed the least relative change. Regression analysis demonstrated that the greatest change in percentage sensitivity of CPS occurred to gentamicin and cephalothin and the least change occurred to penicillin and ampicillin. Recent canine clinical isolates of CPS, specifically identified as Staphylococcus intermedius (n = 109), were uniformly sensitive to novobiocin, amikacin, tobramycin, spectinomycin, and amoxicillin-clavulanic acid. Twenty-two isolates were also sensitive to 17 other antimicrobics. Eighty-seven isolates were resistant to 1 or more antimicrobics tested. Resistance was most common to sulfonamides, penicillin G, ampicillin, tetracycline, and streptomycin. Differences in susceptibility results between S intermedius and unspecified CPS were not statistically significant.

Disseminated protothecosis in a dog.

A dog with forelimb lameness, bilateral retinal detachment, and hemorrhagic diarrhea, died. Necropsy demonstrated multifocal lesions in the skeletal musculature, myocardium, liver, thyroid glands, kidneys, eyes, and brain. Microscopically, the lesions contained numerous organisms and minimal cellular infiltrates. The morphologic and cultural characteristics of the organisms were similar to prototheca. The organisms in tissue sections reacted positively for Prototheca zopfii, using an indirect fluorescent antibody technique.

Species of Staphylococcus isolated from animal infections.

One hundred randomly selected clinical strains of staphylococci were identified by species using a commercial micromethod system. Eight species of staphylococci were identified. Staphylococcus intermedius was the most frequent (n = 74) species identified and accounted for 70/74 (94.6%) of the coagulase-positive strains and 70/79 (88.6%) of the total isolates from dogs. Other species identified, in order of their frequency, included S. epidermidis (8), S. aureus (7), S. simulans (4), S. sciuri (2), S. xylosus (2), S. hyicus (2) and S. saprophyticus (1). These results show that at least 8 different species of staphylococci can be recovered from animal infections and that coagulase-positive species such as S. intermedius may be more common than S. aureus. The relative significance of these other species in animal infections needs to be assessed.

Fatty acid composition of equine erythrocytes.

Fatty acid composition of erythrocytes of healthy horses was determined. Three fatty acids (C16:0, C18:0, and C18:1) were found in approximately equal quantities and comprised 72.17% of the total. Nine other fatty acids were found in small amounts. Saturated fatty acids constituted 67.2% of the total. Marked variation was demonstrated in the occurrence and distribution of fatty acids in the sterol ester, triglyceride, phospholipid, and free fatty acid fractions.