SAN FRANCISCO — There are two important things to know about the recently identified threat of staphylococcal necrotizing pneumonia: It generally follows an influenza illness, and a physician seeing a patient in the clinic or office is not going to miss it.
That was the message of John G. Bartlett, M.D., who has been involved with four cases of necrotizing pneumonia seen in Baltimore recently. All of the cases occurred during a period of 2 months in the winter of 2003–2004, and all were community acquired, he said at the annual meeting of the American College of Physicians.
“These patients are not subtle. They are severely ill,” said Dr. Bartlett, chief of the division of infectious diseases at Johns Hopkins University, Baltimore.
Each of the four cases occurred in previously healthy individuals without risk factors for staphylococcal infection. The disease is rare, and a physician would likely recognize right away that he or she was not dealing with bronchitis or viral pneumonia.
These infections appear to progress rapidly. Two of the patients had been vomiting, and each had severe dyspnea and/or hemoptysis and shock.
Staphylococcal pneumonia is generally a superinfection following influenza. Two patients had serologic evidence of influenza A infection; two were not tested but were found to have an influenza-like prodrome. One patient died, and two needed below-the-knee amputations. The only bacterial pathogen recovered was methicillin-resistant Staphylococcus aureus (MRSA), giving further evidence that methicillin resistance is becoming more prevalent among community-acquired staph infections.
Necrotizing pneumonia has previously been reported in Europe. A paper published in April in the New England Journal of Medicine reported 14 cases of MRSA necrotizing fasciitis, and an article in the same issue said that 8%–20% of MRSA isolates collected by laboratories do not come from hospitals.
MRSA in the community is different from MRSA in the hospital, Dr. Bartlett said. Hospital-acquired MRSA is generally resistant to trimethoprim/sulfamethoxazole, doxycycline, clindamycin, rifampin, and the quinolones. Community-acquired MRSA tends to be susceptible to those agents, but it often has genes for Panton-Valentine leukocidin, the presumed virulence factor for its necrotizing ability.