1. Staph aureus with cefazolin: SUSCEPTIBLE. This report means that the isolated bacteria is sensitive to the first generation cephalosporin. It means that the organism is most likely MSSA and it is appropriate to treat the infection with cephalexin (Keflex), a first-generation cephalosporin.
2. Staph aureus with cefazolin: RESISTANT. This report indicates MRSA and one should treat it with doxycycline, clindamycin, trimethoprim/sulfamethoxazole or linezolid for oral therapy, or vancomycin, linezolid, daptomycin (Cubicin, Cubist Pharmaceuticals) or tigecycline (Tygacil, Pfizer) for IV therapy, based on the culture and sensitivity report.
3. Coagulase-negative Staphylococcus. This is a common skin flora and rarely a disease-causing agent. This could mean one of two things. You may not have taking a good enough culture sample to isolate the disease-causing bacteria. Alternately, this finding could mean the wound is not infected but is perhaps red and inflamed from other reasons. For example, one may consider an allergic reaction to the wound dressing.
Pertinent Insights On Diagnosing And Treating Infected Wounds
Any open wound is a portal of entry for bacteria and there is a possibility of wound infection, oftentimes with gram-positive bacteria, such as Staphylococcus or Strep species. It is very important to diagnose and treat these conditions swiftly in order to achieve optimal outcomes. Accordingly, our expert panelists explore how to diagnose and treat wound infections, offering a variety of insights on antibiotics and culturing.
How do you identify and diagnose wound infection?
Kazu Suzuki, DPM, CWS, advises students to use their senses to detect infection. He says one must hear (patient complaints of pain), see (redness and swelling), touch (swelling and skin changes) and smell (infected wounds). He directs the most attention to the patient’s complaint of wound pain. If the wound pain increases for any reason, he says one must suspect infection as the top reason for the increased amount of pain. Dr. Suzuki notes that even patients with profound diabetic neuropathy can experience wound pain in the face of infection.
Although blood test results (such as white blood count, sedimentation rate and C-reactive protein) can be helpful, Dr. Suzuki considers those tests markers of infection rather than definitive diagnostic tools of wound infection. For example, he monitors those lab values for a response to the antibiotics prescribed to a particular patient. He treats many patients with diabetes, cancer patients (on chemotherapy) and transplant patients (on immunosuppressive medications) so it is not uncommon to see completely “normal” lab values when these patients have an active wound infection.
Based on their observational data of wound infections, Dr. Suzuki cites Sibbald and colleagues for the mnemonics of NERDS (superficial infections that should be treated with topical antimicrobials) and STONEES (deep infection that should be treated with systemic antibiotics).1 NERDS means Non-healing, Exudate, Red + Bleeding, Debris, Smell. STONEES means Size is bigger, Temperature, Os (exposed bone), New breakdown, Exudate, Erythema and Edema, and Smell.
Warren Joseph, DPM, FIDSA, uses clinical signs and symptoms to diagnose a wound infection. As a member of the Infectious Diseases Society of America (IDSA) Diabetic Foot Infection Guidelines Committee, he has investigated the literature on the topic in order to make evidence-based recommendations.
“Nothing has convinced us to change thinking between our original 2004 guidelines and the newly revised document (to be published in late 2011 or early 2012)” notes Dr. Joseph. He says the 2004 guidelines emphasize clinical signs and symptoms as being key to the diagnosis of a wound infection.2 Along with the classic “primary” signs including redness, swelling and heat, Dr. Joseph cites the possibility of “secondary” signs such as poor quality of granulation tissue, increased drainage, tunneling and odor.
Kathleen Satterfield, DPM, says a frank infection “is really no problem” as far as the diagnosis goes. She says the real problem is with the infection that is on the edge, especially the one with no portal or a small portal of entry. To complicate things, Dr. Satterfield notes that patients with diabetes can have leukocyte dysfunction and, as a result, are sometimes unable to mount a response to a localized or even systemic infection. These patients may not have a high white blood cell count or a fever.
“That is when you have to rely on clinical experience and if you do not have that yet, you seek out others who do have that gray hair. You do not want to learn by catastrophe,” says Dr. Satterfield.