It has been shown that people and pets can harbour identical strains of meticillin-resistant (MR) staphylococci when they share an environment. Veterinary dermatology practitioners are a professional group with a high incidence of exposure to animals infected by Staphylococcus spp. The objective of this study was to assess the prevalence of carriage of MR Staphylococcus aureus (MRSA), MR S. pseudintermedius (MRSP) and MR S. schleiferi (MRSS) by veterinary dermatology practice staff and their personal pets. A swab technique and selective media were used to screen 171 veterinary dermatology practice staff and their respective pets (258 dogs and 160 cats). Samples were shipped by over-night carrier. Human subjects completed a 22-question survey of demographic and epidemiologic data relevant to staphylococcal transmission. The 171 human-source samples yielded six MRSA (3.5%), nine MRSP (5.3%) and four MRSS (2.3%) isolates, while 418 animal-source samples yielded eight MRSA (1.9%) 21 MRSP (5%), and two MRSS (0.5%) isolates. Concordant strains (genetically identical by pulsed-field gel electrophoresis) were isolated from human subjects and their respective pets in four of 171 (2.9%) households: MRSA from one person ⁄ two pets and MRSP from three people ⁄ three pets. In seven additional households (4.1%), concordant strains were isolated from only the pets: MRSA in two households and MRSP in five households. There were no demographic or epidemiologic factors statistically associated with either human or animal carriage of MR staphylococci, or with concordant carriage by person-pet or pet-pet pairs. Lack of statistical associations may reflect an underpowered study.
Background
While screening programs have reduced the risk of infectious disease transmission by donors in human and veterinary blood banking, bacterial contamination of blood products has emerged as a major complication in human medicine.
Objectives
To describe a Pseudomonas fluorescens (Pf)-contaminated feline packed RBC (pRBC) unit and experimentally investigate Pf-contaminated canine pRBCs.
Methods
Canine pRBCs were inoculated with Pf-rich pRBCs from the sentinel feline unit and stored at 4°C or 20°C for 72 hours. Aliquots from the pRBCs were serially evaluated by microscopy, culture, and a eubacterial 16S rRNA real-time PCR assay.
Results
One Pf-contaminated feline unit turned black after 22 days of storage and was removed from the blood bank; a source was not found, and no other contaminated units were identified. Canine pRBCs spiked with 5 or 25 μL of the sentinel unit became culture- and/or 16S PCR-positive at ≥8 hours at 20°C and 48 hours at 4°C and developed a color change at ≥24 hours. Sensitivity studies indicated that without incubation, inoculation of ≥100 μL Pf-rich pRBCs was necessary for a positive 16S PCR test result.
Conclusions
P. fluorescens grows in stored pRBCs slowly at 4°C and rapidly at 20°C. Screening of blood products for color change, estimating bacterial concentration with microscopy, and 16S PCR testing are simple and fast ways to detect bacteria in stored blood. Aseptic collection, temperature-controlled storage, and regular visual monitoring of stored units is recommended. Discolored units should not be transfused, but examined for bacterial contamination or other blood product quality problems.
The SCCmec type II element is typically associated with nosocomial MRSA infections of people. Cats may serve as reservoirs for MRSA infections in humans.
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