Search Results

Abstract

Objective—To determine diagnostic accuracy of a compartmented bacteriologic culture and antimicrobial susceptibility testing plate (CCSP) for detection of bacterial urinary tract infection (UTI) in dogs and antimicrobial susceptibility testing of bacterial isolates.

Design—Evaluation study.

Sample—62 frozen, previously characterized bacterial isolates from canine urine cultures and 147 canine urine samples.

Procedures—The study was conducted in 2 phases: preliminary assay validation (phase 1) and diagnostic validation (phase 2). For phase 1, the frozen bacterial isolates were revitalized and tested with the CCSP and with standard aerobic microbiological culture (SAMC). For phase 2, the urine samples were tested with the CCSP and SAMC in parallel.

Results—For phase 1, after 24 hours of culture, 46 of 62 (74%) bacterial isolates had growth on the CCSP and all (100%) had growth in SAMC. For bacterial isolates with growth, the CCSP allowed correct identification of 45 of 46 (98%) isolates. Isolates yielding no growth on the CCSP were gram-positive cocci (Staphylococcus spp [n = 7] and Enterococcus spp [9]). In phase 2, the overall diagnostic accuracy of the CCSP, compared with SAMC, was 94% (sensitivity, 81%; specificity, 99%). The positive predictive value was 98% and negative predictive value was 92%. Susceptibility results for enrofloxacin and trimethoprim-sulfamethoxazole as determined with the CCSP had greatest concordance with those determined by SAMC (71% and 96%, respectively), compared with other antimicrobial susceptibilities.

Conclusions and Clinical Relevance—Use of the CCSP led to accurate exclusion of UTI in dogs without a UTI but was less reliable for diagnosis of UTI, particularly infections caused by gram-positive cocci. Standard aerobic microbiological culture remains the gold standard for detection of UTI in dogs.

Abstract

Objective—To determine whether resistance to oxacillin and other antimicrobials in 3 Staphylococcus spp commonly isolated from dogs increased from 2001 to 2005.

Design—Retrospective case series.

Sample Population—1,772 clinical samples of various types obtained from dogs examined at the University of Tennessee Veterinary Teaching Hospital or at regional veterinary hospitals and submitted to the bacteriology and mycology laboratories associated with the teaching hospital.

Procedures—Samples were submitted by attending veterinarians to the bacteriology and mycology laboratories for routine aerobic microbial culture. Identification and antimicrobial susceptibility procedures were performed on all isolates. Susceptibility reports for each antimicrobial and Staphylococcus spp were determined from aggregate electronically archived test results. Oxacillin and multidrug resistance for Staphylococcus intermedius was analyzed by reviewing disk diffusion zone measurements.

Results—Oxacillin resistance increased among S intermedius isolates during the past 5 years, and the increase was associated with multidrug resistance. In 2005, 1 in 5 Staphylococcus spp isolates from canine clinical samples was resistant to oxacillin. The most common staphylococcal species isolated were S intermedius (n = 37), Staphylococcus schleiferi (21), and Staphylococcus aureus (4), and frequencies of oxacillin resistance in isolates of these species were 15.6%, 46.6%, and 23.5%, respectively.

Conclusions and Clinical Relevance—Veterinarians should be aware of the potential for empiric drug treatment failures in instances where Staphylococcus spp infections are common (eg, pyoderma). Judicious use of bacterial culture and susceptibility testing is recommended.

Abstract

Objective—To determine the methicillin-resistant profile of staphylococcal isolates from the skin of dogs with pyoderma.

Animals—90 dogs with pyoderma.

Procedure—Staphylococci isolated from dogs with pyoderma were tested for susceptibility to methicillin by use of a standard disk diffusion test with oxacillin disks. The DNA extracted from the isolates was tested for the mecA gene that encodes the penicillinbinding protein 2a (PBP2a) by use of a polymerase chain reaction (PCR) assay. The expression of PBP2a was determined with a commercial latex agglutination assay. Species of staphylococcal isolates were identified by use of morphologic, biochemical, and enzymatic tests.

Results—Most of the isolated staphylococci were methicillin-susceptible, coagulase-positive Staphylococcus intermedius isolates. Whereas only 2 of 57 S intermedius isolates were resistant to methicillin, approximately half of the isolates had the mecA gene and produced PBP2a. Staphylococcus schleiferi was the second most common isolate. Widespread resistance to methicillin was found among S schleiferi isolates. More coagulase-negative S schleiferi isolates were identified with mecA gene-mediated resistance to methicillin, compared with coagulase-positive S schleiferi isolates.

Conclusions and Clinical Relevance—The latex agglutination assay for the detection of PBP2a expression coupled with the PCR assay for the mecA gene may provide new information about emerging antimicrobial resistance among staphylococcal isolates. (Am J Vet Res2004;65:1265–1268)

Abstract

Objective—To determine the frequency of isolation and susceptibility patterns of Staphylococcus schleiferi from healthy dogs and dogs with otitis, pyoderma, or both that had or had not received antimicrobial treatment.

Design—Prospective study.

Animals—50 dogs.

Procedure—Dogs were allocated to 1 of 4 groups: healthy dogs (n = 13), dogs without otitis but with pyoderma (10), dogs with otitis but without pyoderma (11), and dogs with otitis and pyoderma (16). Bacteriologic culture of ear swab specimens was performed in all dogs. Bacteriologic culture of skin swab specimens was also performed in dogs with concurrent pyoderma. Isolates were identified as S schleiferi subsp schleiferi or S schleiferi subsp coagulanson the basis of growth and biochemical characteristics.

Results—S schleiferi was not isolated from any dogs with pyoderma only. Staphylococcus schleiferi subsp schleiferi was isolated from the ears of 2 healthy dogs, and the skin and ears of 2 dogs and the skin of 1 dog with otitis and pyoderma. Staphylococcus schleiferi subsp coagulans was isolated from the ears of 3 dogs with otitis only, and the ears of 6 dogs and the skin of 2 dogs with otitis and pyoderma. One of the S schleiferi subsp schleiferi isolates from ears, 2 of the S schleiferi subsp coagulansisolates from ears, and 1 of the S schleiferi subsp coagulansisolates from the skin were resistant to methicillin. One methicillin-resistant isolate from the ears and 1 from the skin were also resistant to fluoroquinolones.

Conclusions and Clinical Relevance—S schleiferi subsp schleiferiwas detected in healthy dogs and dogs with otitis and pyoderma. Methicillin-resistant and -susceptible S schleiferi subsp schleiferi and S schleiferi subsp coagulans were detected as the predominant organisms in dogs with otitis. ( J Am Vet Med Assoc 2005;227:928–931)