Etiology and outcome of community-acquired lung abscess.
BACKGROUND
Anaerobes are the first and Streptococcus species the second most common cause of community-acquired lung abscess (CALA) in the West. The etiologic pathogens of this disease have changed in Taiwan, with Klebsiella pneumoniae being reported as the most common cause of CALA.


OBJECTIVE
To determine the etiologies of community-acquired lung abscess.


METHODS
We retrospectively reviewed the records of 205 Japanese adult patients with CALA to evaluate etiologies and outcomes. We used not only traditional microbiological investigations but also percutaneous ultrasonography-guided transthoracic needle aspiration and protected specimen brushes.


RESULTS
Of these 205 patients, 122 had documented bacteriological results, with 189 bacterial species isolated. Pure aerobic, mixed aerobic and anaerobic, and pure anaerobic bacteria were isolated in 90 (73.8%), 17 (13.9%), and 15 (12.3%) patients, respectively. The four most common etiologic pathogens were Streptococcus species (59.8%), anaerobes (26.2%), Gemella species (9.8%), and K. pneumoniae (8.2%). Streptococcus mitis was the most common among the Streptococcus species. Mean duration of antibiotic administration was 26 days. Six patients (2.9%, 3 with actinomycosis and 3 with nocardiosis) were treated with antibiotics for 76-189 days. Two patients with anaerobic lung abscess died.


CONCLUSIONS
The first and second most common etiologic pathogens of CALA in our hospital were Streptococcus species and anaerobes, respectively. The etiologies in our study differ from those in Taiwan and are similar to those in the West with the exception that Streptococcus species were the most common etiologic pathogens in our study whereas anaerobes are the most frequent etiologic pathogens in Western countries. S. mitis and Gemella species are important etiologic pathogens as well. The identification of Actinomyces and Nocardia is important in order to define the adequate duration of antibiotic administration.
Takayanagi
Noboru
N
Department of Respiratory Medicine, Saitama Cardiovascular and Respiratory Center, Saitama, Japan. takayanagi.noboru@pref.saitama.jp
Kagiyama
Naho
N
Ishiguro
Takashi
T
Tokunaga
Daidou
D
Sugita
Yutaka
Y
D000196:Actinomycosis / Q000150:complications*; D000368:Aged; D001420:Bacteria, Aerobic / Q000302:isolation & purification; D001421:Bacteria, Anaerobic / Q000302:isolation & purification; D001707:Biopsy, Needle; D005260:Female; D006801:Humans; D008168:Lung / Q000473:pathology; D008169:Lung Abscess / Q000150:complications / Q000175:diagnosis / Q000382:microbiology* / Q000628:therapy; D008297:Male; D008875:Middle Aged; D009617:Nocardia Infections / Q000150:complications*; D012189:Retrospective Studies; D012307:Risk Factors; D013291:Streptococcus / Q000302:isolation & purification