11. Culture and Susceptibility Testing
When you explain to Joyce that you are concerned about resistant bacteria she becomes very concerned. She explains that her aunt recently had a horrible skin infection that wouldn’t respond to antibiotic therapy, and she thinks it was a staph infection. She asks if Junior could have the same infection and if he could give it to her kids.
You try to calm Joyce down by explaining what you know about staphylococcal skin infections. Just as Staphylococcus intermedius is a common inhabitant of healthy dog skin and mucosa but can cause canine pyoderma, Staphylococcus aureus is a common inhabitant of healthy human skin and mucosa but can also cause infections. However, you explain to Joyce that while you cannot say for sure, her aunt most likely had an S. aureus infection whereas Junior most likely has an S. intermedius infection. You also explain that it has been reported that S. intermedius can occasionally be transmitted from dogs to humans, and although S. aureus is primarily found in people, animals can also become colonized or infected by this bacterium. You tell Joyce that the culture and susceptibility test will tell you what type of Staphylococcus species is causing Junior’s pyoderma and what antibiotic will best treat it. You stress that in the meantime, the family can avoid transfer of bacteria/bacterial infection by practicing good hygiene (especially those in close contact with Junior) and by giving and applying prescribed medications as directed.
Joyce agrees to the culture and susceptibility test, so you rupture a pustule on Junior’s belly with a 25-gauge needle and collect the small amount of pus with a swab (see previous sidebar – 05a) and submit it for culture and susceptibility. Before Joyce and Junior leave your clinic, you provide Joyce with an informational handout about the common antibiotic resistant staph infection seen in people (Methicillin-resistant Staphylococcus aureus or MRSA) and how to help protect people who have pets with MRSA - Links Below.
Methicillin-resistant Staphylococcus aureus (MRSA) Information Sheet (Appendix A)