Antibiotic exposure a risk for pediatric MRSA

There is a nice case-control study in this month's Archives of Pediatric and Adolescent Medicine by Schneider-Lindner et al. in Quebec. Cases were kids 1-19 yo with outpatient MRSA and controls were matched on age and practice. The primary exposure was receipt of antibiotics between 30 and 180 days prior to MRSA infection. In the abstract, they even said they excluded antibiotic prescriptions within 30-days of MRSA infection to prevent protopathic bias. How cool is that! They said protopathic bias in the abstract! Oh, protopathic bias occurs when a treatment is unknowingly prescribed for an early manifestation of the disease, which has not yet been diagnosed.

They found that 53% of cases and 14% of controls had prior antibiotic exposure. So, 47% of MRSA cases in children occurred without recent antibiotic exposure. After multivariable analysis, the adjusted OR for exposure to any antibacterial was 3.5 (95% CI 2.6-4.8). As an example of a nice dose-response curve, the ORs increased with the number of prescriptions with a OR of 2.2, 3.3, 11.0 and 18.2 for 1, 2, 3, and more than 4 prescriptions, respectively.

I was going to write some additional comments in this space and even thought about writing something obnoxious like "Antibiotics Cause Resistance! Thank you Captain Obvious" But then I came across these nice comments in Reuters Health by honorary Canadian and famous co-blogger Dan, which I will post below.

• "This just provides more evidence to support redoubling our efforts to decrease antibiotic use," Dr. Daniel J. Diekema, who was not involved in the new work, told Reuters Health.

• "It (MRSA) remains a major public health problem, but the dramatic increase that we saw during the last decade seems to have leveled off in many areas and may be decreasing in some," said Diekema, an expert in infectious diseases at the University of Iowa in Iowa City.

• "In general, only a minority of people who carry MRSA go on to become infected," Diekema explained.

• "Observational studies like this really can't prove causality," said Diekema. But he added that it was biologically plausible that antibiotic use would fuel the growth of resistant bacteria.

Schneider-Lindner et al. Arch Pediatr Adolesc Med, August 1, 2011

Reuter's Health, August 11, 2011