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.