S. aureus-related pneumonia increased in recent years

Marquez MA. Pediatr Infect Dis J. 2011;doi:10.1097/INF.0b013e31821618be.

Community-acquired Staphylococcus aureus-related pneumonia has increased in prevalence in recent years, according to a study published online.

Maria A. Carrillo-Marquez, MD, and colleagues from Baylor College of Medicine reported the findings, which looked at 117 patients with community-acquired methicillin-resistant Staphylococcus aureus-related pneumonia who were admitted to the hospital between 2001 and 2009. The researchers reviewed medical records and conducted genotyping of isolates.

Researchers said the rate of S. aureus-related pneumonia nearly doubled, from 4.81 hospitalizations in 2001 to 9.75 by 2009. MRSA was the culprit in 74% of cases, and the USA300 clone, which is associated with the community-acquired type of MRSA, represented 92% of the MRSA and half of the methicillin-susceptible S. aureus (MSSA) isolates, which the researchers said was statistically significant.

Patients with MRSA were typically younger than those with MSSA; viral coinfection was associated with respiratory failure in 15% of the patients; and video-assisted thoracoscopy was more common in patients with USA300 infections, according to the researchers.

“Eighty-nine, 25 and three had video-assisted thoracoscopy, thoracentesis and lobectomy, respectively,” the researchers wrote, noting that it was used more commonly in children with the USA300 genotype.

They said there was one death among the study patients, with most patients noting improvement or cure. Most of the patients were treated with clindamycin, leading the researchers to conclude that clindamycin is an “effective treatment,” in their hospital. They encouraged further studies to examine the optimal treatment for CA-MRSA-related pneumonia.

Disclosure: The researchers reported no relevant financial disclosures.

This excellent retrospective study from Texas Children’s Hospital highlights at least three important aspects of staphylococcal pneumonia in childhood. The first is the significant increase in staphylococcal pneumonia in the last 10 years, particularly for the USA300 pulse type (both MRSA and MSSA). Given the vast armamentarium of virulence determinants found in these isolates, including the nearly ubiquitous PVL, new therapeutics and vaccines should focus on this highly virulent strain. The second is the frequency of respiratory viral coinfection, which was associated with longer PICU stays, formation of empyema, a higher likelihood of respiratory failure, and higher mortality (5% vs. <1%). This illustrates, yet again, the importance of primary prevention of respiratory viruses in children (eg, influenza vaccination), some of which are highly adept at promoting bacterial superinfection with staphylococci.

The third important contribution is the role of the protein synthesis inhibitor, clindamycin, in the treatment of children with CA-staphylococcal pneumonia. The newly published IDSA Guidelines on the Treatment of MRSA advocate vancomycin as primary therapy, but suggest that clindamycin may be effective therapy in children without ongoing bacteremia or an intravascular infection. These data support this practice, at least in areas where clindamycin resistance is low (ie, <10%). Whether it is used in combination with vancomycin or as empiric therapy alone remains an unanswered question.

– C. Buddy Creech, MD, MPH
Assistant Professor, Pediatric Infectious Diseases
Associate Director, Vanderbilt Vaccine Research Program
Vanderbilt University School of Medicine and the Monroe Carell, Jr. Children’s Hospital at Vanderbilt

Disclosure: Dr. Creech reports no relevant financial disclosures.

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