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ATHENS, GA – Despite the conventional wisdom, sometimes hoof beats in the emergency department really might point to a zebra, not a horse.
A pair of new meta-analyses published in the Annals of Family Medicine finds high rates of atypical bacterial pathogens in patients with acute lower respiratory tract diseases, including cough, bronchitis, and community-acquired pneumonia (CAP).
“Because these atypical pathogens do not respond to beta-lactams, may carry a different prognosis, and can cause serious complications in some patients, it is important to understand their prevalence,” the researchers explain. “Therefore, we performed a meta-analysis to describe the prevalence of atypical pathogens among two groups: patients with cough, acute bronchitis, or LRTI in the ambulatory setting and patients diagnosed with CAP. We also compared these ‘real world’ prevalences with the prevalences reported by surveillance systems, where available.”
Analyzing 50 studies, the University of Georgia Health Sciences Campus-led researchers determined that, among adults with CAP, 14% had an atypical pathogen: 7% had Mycoplasma pneumoniae, 4% had Chlamydophila pneumoniae, and 3% had Legionella pneumophila.
Among children with CAP, meanwhile, results showed that 18% had Mycoplasma pneumoniae, only 1% had Chlamydophila pneumoniae. Legionella pneumophila was extremely rare, diagnosed only once in a group of 1,765 patients, the study notes.
Bordetella pertussis was identified among 9% of adults and 18% of children with prolonged coughs.
“Atypical bacterial pathogens are relatively common causes of lower respiratory diseases, including cough, bronchitis, and CAP,” study authors conclude. “Where surveillance data were available, we found higher prevalences in studies where all patients are tested for these pathogens. It is likely that these conditions are underreported, underdiagnosed, and undertreated in current clinical practice.”
In the second meta-analysis, the same researchers found high rates of both Group C beta-hemolytic streptococcus and Fusobacterium necrophorum in patients presenting with sore throat.
They note that, while most cases of sore throat are viral, and Group A beta-hemolytic streptococci are responsible for 10% of cases in adults and up to 30% of cases in children, recent research has suggested that these two other bacteria may be important causes of pharyngitis with similar clinical presentations.
Analysis of 16 studies revealed overall prevalences of Group C streptococcus and F. necrophorum of 6% and 19%, respectively, in patients presenting with sore throat in primary care, the review notes.