Presence of Qac genes in clinical isolates of methicillin-resistant and methicillin-susceptible Staphylococcus pseudintermedius and their impact on chlorhexidine digluconate susceptibility.

OBJECTIVE: To evaluate the presence of quaternary ammonium compound (QAC) (resistance genes, qac A/B, smr, qacG, and qacJ, in clinical isolates of methicillin-susceptible Staphylococcus pseudintermedius (MSSP) and methicillin-resistant S pseudintermedius (MRSP) from dogs and the impact on in vitro chlorhexidine susceptibility. STUDY DESIGN: Experimental in vitro study. SAMPLE POPULATION: Seventy isolates from dogs colonized or infected with MRSP (n = 50) or MSSP (n = 20). METHODS: Agar dilution was used to determine the minimum inhibitory concentration (MIC) of chlorhexidine digluconate. Real-time polymerase chain reaction was used to detect the presence of QAC resistance genes, qacA/B, smr, qacG, and qacJ genes. RESULTS: One or more qac genes were identified in 52 of 70 (74%) isolates. Overall, there was no association between chlorhexidine MIC and the presence of one or more qac genes (P = .85) or the presence of qacA/B (P = .31), smr (P = .72) or qacJ (P = .93) individually. There was an association between qacG and MIC (P = .012), with a median MIC of 1.5 µg/mL for isolates possessing this gene and 1 µg/mL for those not possessing it. CONCLUSION: Quaternary ammonium compound resistance genes were present in MRSP and MSSP isolates. With the exception of qacG, the presence of these genes was not associated with increased MIC. All isolates exhibited MIC 5000 to 80 000 times lower than the concentration recommended for use. CLINICAL SIGNIFICANCE: Despite the presence of QAC genes, chlorhexidine digluconate should be effective against MRSP and MSSP if used correctly.

Invasive cutaneous angiomatosis and thrombocytopenia in a cat.

CASE DESCRIPTION: A 9-year-old 6.9-kg (15.18-lb) castrated male Siamese cat was evaluated because of a 3-year history of repeated hemorrhage from the right metacarpal pad. CLINICAL FINDINGS: Physical examination findings were unremarkable except for a 2-mm-diameter erosion of the right metacarpal pad. A CBC revealed marked thrombocytopenia. Serum biochemical analyses, retroviral screening, thoracic radiography, and abdominal ultrasonography revealed no abnormalities. Via ultrasonographic examination, the vasculature in the right metacarpal pad appeared increased, compared with that of the left pad; an aberrant arterial plexus that was confined to the metacarpal pad was identified via arterial angiography. TREATMENT AND OUTCOME: Surgical resection of the metacarpal pad (without digital pad transposition) with primary closure was performed. Histologic evaluation of the pad tissue revealed invasive cutaneous angiomatosis. The incision healed without complications, and limb function was considered normal. Administration of prednisone (2 mg/kg [0.91 mg/lb], PO, q 24 h) was initiated 4 weeks prior to surgery to treat suspected immune-mediated thrombocytopenia and continued afterwards with a tapering dosage. Platelet count was within reference limits 4 months after surgery; at 12 months, there was no evidence of recurrence of abnormal vasculature in the right metacarpal pad region. CLINICAL RELEVANCE: Complete resection of the metacarpal pad (without pad transposition) resulted in successful and well-tolerated treatment of cutaneous angiomatosis of the metacarpal pad of a cat. Recurrence of abnormal vasculature was not evident at a 12-month follow-up examination. Thrombocytopenia is commonly associated with vascular anomalies in humans and may have been a contributing factor in this cat.

Biomechanical Properties of the 1.5 mm Locking Compression Plate: Comparison with the 1.5 and 2.0 mm Straight Plates in Compression and Torsion.

OBJECTIVES: The purpose was to compare the biomechanical properties of a 1.5 mm locking compression plate (1.5 LCP) to the 1.5 mm straight plate (1.5 P), 1.5 mm straight plate stacked (1.5 PSt) and 2.0 mm straight plate (2.0 P) in compression and torsion. We hypothesized that biomechanical properties of the 1.5 LCP would be equivalent to properties of the 1.5 P and would represent an alternative for the treatment of radial fractures in miniature breed dogs in which those plates would be used. MATERIALS AND METHODS: A 1 mm fracture gap model was created with a bone surrogate stabilized with a six-hole plate. Sixteen constructs were built for each of the four plate configurations. Eight constructs from each group were tested in compression to failure and eight constructs were tested in torsion to failure. RESULTS: In compression testing, the 1.5 LCP was stiffer than the 1.5 P, and had similar stiffness than the 1.5 PSt and the 2.0 P. The load at yield of the 1.5 LCP was slightly lower than the 1.5 P. In torsion, the 1.5 LCP and 1.5 P had similar stiffness, but 1.5 LCP was slightly stronger than 1.5 P. The 1.5 PSt and 2.0 P were overall superior to the 1.5 LCP but only marginally so for the 1.5 PSt. CLINICAL RELEVANCE: The 1.5 LCP can be considered biomechanically equivalent to the 1.5 P under the present experimental conditions. The use of the 1.5 LCP can be considered as an option for radial fracture repair in dogs in which a 1.5 P would have otherwise been used. The use of a locking plate to improve overall success rate, in these fractures, remains to be confirmed clinically.

Ex vivo torsional properties of a 2.5 mm veterinary interlocking nail system in canine femurs. Comparison with a 2.4 mm limited contact bone plate.

OBJECTIVE: To evaluate the torsional properties of the Targon® Vet Nail System (TVS) in small canine femurs and to compare these properties to those of the 2.4 mm LC-DCP® plates. METHODS: Thirty-six cadaveric femurs were allocated to three groups (n = 12). In all bones, points just distal to the lesser trochanter and just proximal to the fabellae were marked and a midshaft transverse osteotomy was performed. Group 1: bones were fixed with the 2.5 mm TVS with the bolts applied at the pre-identified marks. Group 2: A TVS system with 25% shorter inter-bolt distance was used. Group 3: A 7-hole 2.4 mm LC-DCP® plates were applied. All constructs were tested non-destructively for 10 cycles, followed by an acute torsion to failure. RESULTS: Torque at yield was 0.806 ± 0.183 and 0.805 ± 0.093 Nm for groups 1 and 2 and 1.737 ± 0.461 Nm for group 3. Stiffness was 0.05 ± 0.01, 0.05 ± 0.007, and 0.14 ± 0.015 Nm/° for groups 1 to 3 respectively. Maximal angular displacement under cyclic loading was 16.6° ± 2.5°, 15.6° ± 2.1°, and 7.8° ± 1.06° respectively. There was no significant difference for any of the parameters between groups 1 and 2. Both torque at yield and stiffness were significantly greater between group 3 and groups 1 and 2. CLINICAL SIGNIFICANCE: The TVS had approximately half the torsional strength and approximately 1/3 of the stiffness of the 2.4 mm bone plate. Slippage of the locking mechanism was probably the cause of the early failure. The system should be considered as a low-strength and low-stiffness system when compared to bone plates.