Cutaneous antimicrobial preparation prior to intravenous catheterization in healthy dogs: clinical, microbiological, and histopathological evaluation.

The purpose of this study was to determine the effects of a one-minute chlorhexidine gluconate skin preparation protocol prior to cephalic vein catheterization. Twenty-three healthy beagle dogs had one leg aseptically prepared and the opposite leg served as a control. Twenty-six- and 77-hour time groups were studied. Chlorhexidine-treated legs had significantly lower cutaneous bacterial counts than the control legs prior to catheter insertion and prior to catheter withdrawal for both time groups. Control legs developed significantly more dermatitis than the treated legs after 77 h. A one-minute preparation with 4% chlorhexidine gluconate was an effective method for sustained reduction of cutaneous bacterial counts at peripheral intravenous catheter insertion points in dogs. Increased cutaneous bacterial counts were associated with significantly more microscopic dermatitis in untreated legs after 77 h of catheterization.     

Characterization of the protective response against a homologous challenge infection with Strongyloides venezuelensis in rats

The protective response in rats against a homologous challenge infection with Strongyloides venezuelensis was characterized. In an initial infection with 1000 filariform larvae and migrating larvae (L(3)) of S. venezuelensis, the population of L(3) in the lungs on day 3 postinfection (PI), and that of adult worms in the small intestine on day 7 PI, were 180.8+/-14.5 and 336.8+/-70.7, respectively. The latter were gradually expelled towards day 42 PI. After the initial infection, the rats developed strong immunity against a homologous challenge infection as manifested by a marked reduction in worm populations, stunted body length and width, damage to reproductive organs, impaired egg production and rapid expulsion of the worms by day 14 after challenge. Expulsion of the worms was preceded by a significantly elevated (P<0.05) peripheral blood eosinophil (PBE) count, both in the initial (200.0+/-26.5 x 10(3)ml) and the challenge infection (400.9+/-165.4 x 10(3)ml). These findings suggest that rats acquire strong homologous immunity following initial exposure to S. venezuelensis. It is suggested that PBEs are involved in worm expulsion. A major target of these effector mechanisms is the reproductive system of S. venezuelensis.     

Evaluation of the Sprague-Dawley rat as a model for vertical transmission of Brucella abortus

Vertical transmission of Brucella abortus in Sprague-Dawley (SD) rats was verified with microbiologic, serologic, and polymerase chain reaction (PCR) methods. The 38 initially Brucella-free SD rats, weighing 200 to 250 g, were injected subcutaneously with 50 microL of a suspension containing 1 x 10(9) colony-forming units (cfu) of B. abortus biotype 1 Korean isolate. The rats were allowed to mate with uninfected SD rats. The isolate was detected by culture and by AMOS (abortus, melitensis, ovis, suis) PCR in testis tissue of infected male rats and splenic tissue of infected female rats. By 7 d after inoculation, the results of both the rose bengal test (RBT) and the plate agglutination test (PAT) were positive for antibody against B. abortus; the reciprocal antibody titre ranged from 200 to 400 in the 1-mo-old offspring and 800 in their dams. The infected rats directly transmitted Brucella to their breeding partners and offspring. Fetuses of infected dams were found to be infected at 20 d of gestation. These data are discussed in relation to a model for epizootic and zoonotic cases possibly involving wild animals. Additional rigorous experiments are warranted to explore the value of this model in developing measures to prevent congenital brucellosis.     

Evaluation of activity of selected ophthalmic antimicrobial agents in combination against common ocular microorganisms

OBJECTIVE: To determine in vitro efficacy of gentamicin, tobramycin, and miconazole when used in combination, with or without atropine, against Pseudomonas or Aspergillus sp. PROCEDURE: Selected ophthalmic agents were combined for predetermined times. Sterile disks impregnated with the combined solutions were prepared and placed on Mueller-Hinton plates that were seeded with Pseudomonas or Aspergillus sp. Zones of growth inhibition were measured at postincubation hours 24 and 48. RESULTS: Tobramycin alone inhibited growth of Pseudomonas sp, whereas miconazole inhibited growth of Aspergillus sp. Significant differences in zones of growth inhibition when atropine was combined with tobramycin, when gentamicin was combined with miconazole, or when atropine was combined with miconazole and gentamicin, were not detected. CLINICAL RELEVANCE: Combining selected ophthalmic therapeutic agents for as long as 6 hours does not appear to alter the in vitro efficacy of the agents against microorganisms used in this study.     

Brucella abortus infection in indigenous Korean dogs

Three dogs reared on a dairy farm with a high incidence for Brucella abortus were serologically positive for B. abortus and no other Brucella spp. The identity of the organism was confirmed to be B. abortus by AMOS (abortus melitensis ovis suis)-polymerase chain reaction with specific primers for B. canis. One hundred percent homology of the canine isolate and the bovine pathogen isolated from the farm was demonstrated. The only possible source of infection was infected cattle on the same farm. It is suggested that dogs be routinely included in brucellosis surveillance and eradication programs.     

Evaluation of the effect of pH on in vitro growth of Malassezia pachydermatis

The purpose of this study was to evaluate the effects of pH on the growth of canine Malassezia pachydermatis isolates in vitro. Yeast growth was monitored by measuring the optical density with a spectrophotometer. The growth of American Type Culture Collection and field strains of M. pachydermatis was optimal between the pH values of 4.0 and 8.0, and inhibited at the ranges of 1.0 to 3.0 and 9.0 to 10.0. An analysis of covariance showed no significant differences among the growth curves at pH levels 5.0 to 8.0. Although specific contrast tests showed that the growth slope at pH 4.0 was significantly different from that at pH 5.0 to 8.0, only small, random differences were found when the growth slope at pH 4.0 was compared to the individual slopes at pH 5.0, 6.0, 7.0, and 8.0. The findings of this study suggest that topical acidifying products could be beneficial therapeutic options for cutaneous yeast infections in dogs.     

Methicillin resistance among staphylococci isolated from dogs

OBJECTIVE: To determine whether methicillin-resistant staphylococci from dogs expressed the mecA gene and to determine what proportion of canine staphylococcal isolates positive for the mecA gene were resistant to oxacillin and other antibiotics. SAMPLE POPULATION: 25 methicillin-resistant (10 coagulase-positive and 15 coagulase-negative) and 15 methicillin-susceptible (8 coagulase-positive and 7 coagulase-negative) staphylococci isolated from dogs. PROCEDURE: All strains were tested for methicillin resistance by use of oxacillin agar screening and identified by use of standard techniques. Minimum inhibitory concentrations of 16 antibiotics were determined for all 40 isolates. A polymerase chain reaction method targeting a 533-basepair fragment of the mecA gene was used to detect mecA gene expression. RESULTS: 23 of the 25 methicillin-resistant isolates and none of the methicillin-susceptible isolates possessed the mecA gene. For 10 of 16 antibiotics, the proportion of mecA-positive isolates that were resistant or of intermediate susceptibility was significantly higher than the proportion of mecA-negative isolates that were resistant or of intermediate susceptibility. Only 1 methicillin-resistant coagulase-positive isolate was identified as Staphylococcus intermedius; the other 9 were identified as S. aureus. CONCLUSIONS AND CLINICAL RELEVANCE: Results confirm that staphylococci isolated from dogs may have methicillin resistance mediated by the mecA gene. Isolates positive for the mecA gene were more likely to be resistant to various antibiotics than were isolates negative for the mecA gene. Results suggest that in dogs, infections caused by staphylococci that have the mecA gene may be difficult to treat because of resistance to antibiotics.