Antimicrobial Usage & Spread of Resistance

Karl Roberts kr1 at PGSTUMAIL.PG.CC.MD.US
Thu Jan 23 08:14:50 EST 1997

Thank you Glen. This is good information.
Karl J. Roberts

On Wed, 22 Jan 1997, Glen Tamura wrote:

> Since I happening to prepare for a talk on antimicrobial resistance, I
> thought I'd throw my two cents in. 
> Q: Are community acquired infections by resistant bacteria rare?  
> A: Not any more, with the rise of resistant pneumococci. Recent data
> suggest that 24% of pneumococci isolated from outpatients in the United
> States were not susceptible to penicillin (14.1% intermediate, 9.5%
> high-level resistance, Doern GV et al, Antimicrob Agents Chemother
> 40:1208-13, 1996).
> Q: Where did these bacteria arise from? 
> A: Steven Projan is correct, that most of these isolates appear to first
> appear in third world countries. Any theories on why this might be so are
> purely speculative and without any experimental evidence to back them up. 
> Q: What percentage of kids get antibiotics for viral infections? 
> A: A recent study (Arnold KE et al, J Pediatr 128:757-764, 1996) found
> that nearly 50% of children who were see in pediatricians offices for
> upper respiratory infections and did NOT have otitis media still got
> antibiotics. Admittedly, a fair proportion of these may have had sinusitis
> or bronchitis, for which antibiotic therapy would be appropriate. On the
> other hand, I very  much doubt that anywhere near half of them did. 
> Q: Does use of antibiotics in the outpatient setting select for resistant
> bacteria?
> A: Recent data are quite convincing that antibiotic usage increases the
> rate of carriage of resistant pneumococci by approximatey two-fold (Arnold
> et al, see ref above, and B'edos JP et al, Clin Infect Dis 22:63-72,
> 1996). Furthermore, the risk of carriage of resistant pneumococci in a
> highly treated population (patients with sickle cell anemia take
> prophylactic penicillin on a daily basis) is 62%! Pretty impressive. 
> Q: Steven Projan raises the argument that viral diseases are often
> secondarily infected with bacteria, and that "if only 20% of such
> infections are really bacterial - do we let those 20% suffering from
> bacterial infections get sicker until we get the culture results? Is that
> smart practice? Since when does the Hipocratic (sic) oath say "Do no
> good"? 
> A: It depends on the natural history of the bacterial infection you are
> talking about. 
> 	For serious infections, such as meningitis or pneumonia, empiric
> antibiotic therapy for suspected cases is absolutely necessary, even if
> the risk of disease (pending culture results) is only 5%, let alone 20%. 
> 	However, the vast majority of antibiotic prescriptions in the
> pediatric age group are for otitis media, sinusitis, and bronchitis.
> The natural history of these diseases is relatively benign, and delaying
> therapy for a few days or even a week will not result in any long-term
> harm to the patient. 
> 	The average child will have approximately 10-15 upper respiratory
> viral infections in each of their first two years. It seems silly to
> prescribe antibiotics for all of these is imprudent. This will double the
> risk for THAT PATIENT's developing resistant pneumococcal carriage, thus
> making it much harder to treat the patient when they really need therapy. 
> Glen S. Tamura, M.D., Ph.D.
> Division of Infectious Disease
> Department of Pediatrics
> University of Washington
> Seattle, WA  98105

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