|
|
New Worries About Multidrug-Resistant Bacteria
Community prevalence of multidrug-resistant strains of pneumococci, and of invasive community-based methicillin-resistant Staphylococcus aureus, is increasing.
Two studies raise concerns about the increased prevalence of multidrug-resistant bacteria in community-based settings. The first study consisted of population-based surveillance of invasive methicillin-resistant Staphylococcus aureus (MRSA) infections in nine U.S. communities in 2005, with \"invasive\" defined as isolation of MRSA from a normally sterile body site (e.g., blood, spinal fluid, bone). The 8987 cases were categorized as healthcare-associated with community onset (e.g., presence of invasive device at hospital admission, or a hospitalization, surgery, or residence in a long-term care facility in the previous 12 months), healthcare-associated with hospital onset, or community-associated. The proportions of cases in these three categories were 58%, 27%, and 14%, respectively. The overall incidence rate was 31.8 per 100,000, and the standardized mortality rate was 6.3 per 100,000. The authors estimate that these rates translate to roughly 94,000 invasive MRSA cases in the U.S., with roughly 19,000 deaths.
In the second study, tympanocentesis was performed in 212 children with either first or second episodes of acute otitis media (AOM) or AOM with treatment failure. Of the 212 samples, bacterial pathogens were found in 162, including 94 with Haemophilus influenzae and 59 with Streptococcus pneumoniae. The proportion of pneumococcal isolates not covered by the 7-valent pneumococcal vaccine increased from 2003–2004 (12/28; 43%) to 2005–2006 (14/19; 74%). Among these isolates, the prevalence of multidrug-resistance also increased during this period; although five of nine multidrug resistant infections responded to levofloxacin (the others to tympanostomy tube insertion), the authors argue vigorously for not making the fluoroquinolones the standard antibiotic choice for AOM, citing safety concerns and risk for further resistance.
Comment: Together, these results describe a major and increasingly prevalent problem of bacterial resistance that is not confined to acute medical care settings. Most of the invasive MRSA cases originated outside the hospital, many in people without prior healthcare exposure. The number of cases of AOM with multidrug-resistant pneumococci not covered by the pneumococcal vaccine is small but growing and would be quite ominous if found to be representative of larger populations. An editorialist notes that the estimated number of U.S. deaths from MRSA infection exceeds that attributable to HIV/AIDS in 2005 and calls for expanded and more intense surveillance and infection-control programs.
— Thomas L. Schwenk, MD |
|
发表于 2007-10-27 08:54:42