We? Who’s We??
Dr. Dent raises a very reasonable question, actually. He points out that CAP gets a gram of ceftriaxone in our shop prior to admission, and this is said to cover the bug (Strep pneumo) we are most concerned with getting into our lung. BUT he then goes on to point out our meningitis guidelines. They currently include (up to) 5 drugs:
Ceftriaxone, Vancomycin, Dexamethasone (+/- Ampicillin and Acyclovir)
“What are we covering additionally with Vancomycin?”, he asks.
Umm, nuthin’- I says.
“Huh?”, he counters.
Well, I says, it’s still for Strep – it’s just that in our area S. pneumoniae resistance is up to nearly 30% and Vancomycin is recommended as combination therapy.
“Howzzat??”, he ripostes, brilliantly.
But I see where he’s going with this. Shouldn’t we be giving Vancomycin to our CAP patients in high resistance areas as well? Anyone who gives Vancomycin empirically for bacterial meningitis should likely do so for pneumonia as well, right?
No.
First of all, most of our microbiograms are standardized to call (S)ens, (I)nt, (R)esistant based on expected CSF concentrations. So it depends on where your infection is. As an example, quinolones get into the GU tract so well that you could use ciprofloxacin as monotherapy for Pseudomonas in that setting. Antibiotics don’t get into the CSF as well as they do into other areas, so you get better killing at lower doses in the lung. (Which also explains the steroids used to help with that pesky blood-brain barrier.)
Then there are in vivo differences compared with the in vitro expected killing. Azithromycin resistance is rising among S. pneumo bugs as well. But macrolides haven’t been removed from ID guidelines for this indication, because clinical treatment failure is lagging far behind these rising rates. Since macrolides sit in the cell for a week or so, they can’t be expected to conform to serum concentration predictions.
Finally, we’re scared of meningitis. We don’t want to risk the response to treatment lagging in this group, or developing an abscess if those resistant bugs cause trouble. So it makes sense that S. pneumo in the brain gets all guns brought to bear, while CAP doesn’t see much treatment failure with a cephalosporin alone.
So, yes, the guidelines make sense here. (But if you want to omit the ciprofloxacin from the next HCAP PNA pt., I’m okay with that.)
Pik Mukherji
Program Director, Emergency Medicine, Northwell Health
Dr. Mukherji is the Residency Director at LIJ Medical Center in New Hyde Park, NY. He spends most of his time confusing residents and trying to convince doctors that they overestimate the benefits of treatment and underestimate the harms. He has a passion for education and trying not to do things wrong.
