Treatment of staphylococcal infection is dependent on the site involved, the severity of infection, and the antibiotic susceptibility pattern of the organism causing the infection. Although most serious staphylococcal infections are due to coagulase-positive staphylococci (Staphylococcus aureus), infections due to coagulase-negative staphylococci (eg, Staphylococcus epidermidis) are increasing and may also be life threatening. Staphylococcus aureus is a highly invasive pathogen, able to spread hematogenously to many organs, leading to metastatic foci of infection. Coagulase-negative staphylococci generally require the presence of prosthetic material to gain a foothold and cause infection.
SUSCEPTIBILITY TO ANTIBIOTICS
Staphylococci have a propensity to develop resistance to antibiotics relatively quickly. Virtually all staphylococci should be considered to be resistant to penicillins that are susceptible to penicillinase (eg, amoxicillin, ampicillin, piperacillin, mezlocillin, and ticarcillin). However, the addition of clavulanic acid, sulbactam, or tazobactam to several of the above penicillins renders them resistant to penicillinase and thus useful for treating staphylococcal infections. Examples are amoxicillin–clavulanic acid (Augmentin), ampicillin–sulbactam (Unasyn), pipercillin–tazobactam (Zosyn), and ticarcillin–clavulanic acid (Timentin).
Cephalosporins are useful for the treatment of staphylococcal infections. First-generation cephalosporins (cefazolin, cephalexin) are the most active, followed by second-generation agents (cefuroxime, cefotetan, cefoxitin). Third-generation (ceftriaxone, cefotaxime) and fourth-generation (cefipime) cephalosporins have less activity. Only first-generation cephalosporins should be used for serious staphylococcal infections.