Dr Lipsky, could you provide some clarification on empiric antiobiotic choice?

In table 8, under moderate or severe DFIs, we have the following probable pathogens groups:

1) MSSA; Streptococcus spp; Enterobacteriaceae; obligate anaerobes

So far, everything clear; these are the pts with no risk for MRSA or Pseudomonas; treat them with “usual” antibiotics

2) MRSA – treat with linezolid, daptomycin, or vancomycin

Obvious

3) Pseudomonas - piperacillin-tazobactam

OK

4) MRSA, Enterobacteriacae, Pseudomonas, and obligate anaerobes; suggested antibiotics: vancomycin, ceftazidime, cefepime, piperacillin-tazobactam, aztreonam, or a carbapenem.

Now I have trouble – what clinical scenario is it? Did you mean patients with risk factors for both MRSA and Pseudomonas, and hence the need for very broad-spectrum antibiotics? If so, then we should probably use vancomycin (linezolid, daptomycin) AND one of the remaining (or, maybe more specifically, vancomycin plus piperacillin-tazobactam, because the latter is preferred for Pseudomonas). Why this list is longer, if required spectrum is broader?

Thank you.