I have treated so many patients with sinusitis in the last several weeks, I decided to review new guidelines that were issued by the Infectious Diseases Society of America (IDSA) recently on sinusitis. Wow, the changes were BIG and I had missed them. Seems the drugs I used to use don’t work so well any more.
Everyone has heard about drug resistance. We had to watch a movie about it in medical school in the 1970s. It was very important that we not use antibiotics with broader, more powerful antimicrobial effects than necessary. Else plagues of drug-resistant bacteria would rain down upon us, and we would run out of effective antibiotics.
I got it. Use basic, relatively narrow spectrum antibiotics unless there is a very good reason to use the bigger guns — like your patient was so sick he might not survive if you picked the wrong drug to start.
Plus, there are very few new antibiotics in the pipeline.
I recently learned that 80% of the antibiotics sold in the US don’t treat humans. These antibiotics are used in animal feed, enabling owners of livestock and poultry farms to crowd the animals together, where they frequently live in their own merde. FDA banned this use of fluoroquinolone antibiotics in 2005, but compliance by industry has been poor. (Industry can still feed animals other classes of antibiotics.) So FDA will now restrict sales of this class of antibiotic to only those with a veterinarian’s prescription, and ask farmers for voluntary compliance in reducing use of other antibiotics, 61 years after first approving this practice.
Yale’s Dr. David Katz notes that the use of antibiotics in farm animals is a bigger problem for drug resistance than doctors choosing the wrong antibiotics.
But back to sinusitis: too many of my patients needed a change in antibiotic after 4 days on the first antibiotic. Good drugs for sinusitis used to include penicillins, cephalosporins, macrolides and sulfa drugs: four different categories of drugs. Now they are inadequate, caused by too many resistant Strep. pneumoniae and Hemophilus influenzae, the most common bacteria causing sinusitis.
What now? IDSA’s #1 choice is Augmentin, a very broad spectrum combination of amoxicillin and clavulanic acid. The clavulanic acid prevents most bacterial resistance to amoxicillin. This treatment may cause more drug resistance down the road.
But what if you are allergic to penicillin? Doxycycline or a fluoroquinolone can be used. Doxy can’t be used in children, however. What else should you use? Clindamycin plus a cephalosporin, say the guidelines. But Clostridium difficile infections occur in 1-10% of patients treated with clindamycin. These can be impossible to treat. This is not looking good, I realize.
Then it gets worse. What has happened? IDSA let the cat out of the bag on page e16:
… both the prevalence of H. influenzae (40%– 45%) and proportion of b-lactamase–producing H. influenzae (37%–50%) (extrapolated from middle ear fluid cultures of children with acute otitis media) have markedly increased among other upper respiratory tract infections since the widespread use of conjugated pneumococcal vaccines…
Whereas S. pneumoniae was more common than H. influenzae prior to 2000, the prevalence of H. influenzae has clearly increased while that of S. pneumoniae has decreased in the post–pneumococcal vaccine era, such that currently they are approximately equal… (* See IDSA citation below)
Now 30% of Strep pneumoniae are resistant to macrolides, while 30-40% are resistant to sulfa drugs (page e3). What IDSA didn’t delve into was the fact that non-vaccine Strep serotype 19A, which is multidrug resistant, spread throughout the world as the result of the niche created by vaccination with the 7-serotype vaccine. Recently a replacement pneumococcal conjugate vaccine was licensed that includes 13 serotypes in the US, and varied numbers of serotypes in other countries. Any unintended consequences have yet to be identified.
The strains of Strep pneumoniae circulating among us have changed as a result of the Prevnar 7 vaccine, and the new strains are decidedly more drug resistant. I’d rate this vaccine’s net value a big negative.
Yet the consequences of this change in resistance patterns are profound. Now routine cases of sinusitis, earaches, strep throats and pneumonias have become significantly harder and more expensive to treat. I can’t tell you the relative contributions that Prevnar 7 vaccine, prescribing errors and antibiotic feeding make to this mess. But the serious unintended consequence of Prevnar 7 (the 19A proliferation) needs to be fully grasped, and the lesson absorbed, in order to avoid making a similar mess with other vaccines.
* Casey JR, Adlowitz DG, Pichichero ME. New patterns in the otopathogens causing acute otitis media six to eight years after introduction of pneumococcal conjugate vaccine. Pediatr Infect
Dis J 2010; 29:304–9.