Conundrums in community-acquired pneumonia

To the Editor: The recent editorial on community-acquired pneumonia (CAP) stated that “even in an era in which penicillin resistance appears to be increasing among some Streptococcus pneumoniae isolates, there have been no documented failures of high-dose penicillin in treating pneumococcal pneumonia or bacteraemia”.1

The medical literature suggests otherwise.

Firstly, North American guidelines do not mention penicillin at all, and, in one analysis of 25 996 hospitalised patients who received monotherapy, mortality was about 50% higher with penicillin monotherapy than with monotherapy with ceftriaxone, another cephalosporin, a macrolide or a quinolone.2

More importantly, however, the same study found that the mortality rate in patients (even low-risk patients) treated with two antibiotics, one of which was a macrolide, was half the mortality rate of patients treated with one antibiotic. Dual therapies used were a macrolide agent in combination with ceftriaxone, another cephalosporin, a penicillin or a quinolone. Best outcomes were achieved with a ceftriaxone–macrolide combination.

In a review of seven studies, Waterer3 found that patients with severe pneumococcal pneumonia or bacteraemic pneumococcal disease who were treated with two antibiotics had a significantly lower mortality rate than patients treated with a single antibiotic. This was despite the fact that the patients treated with a single antibiotic were not as ill initially as those treated with two antibiotics.

Research by Waterer and colleagues4 showed that the benefit of taking two antibiotics was most apparent in the highest risk hospitalised patients, in whom mortality was five times higher in those receiving one antibiotic than in those receiving two.

Thus, it is imperative that all patients with severe pneumococcal CAP be treated with two antibiotics, one of which should be a macrolide.