The optimal duration of antimicrobial therapy for lower respiratory tract infection in patients with neuromuscular disorders based on a clone library analysis of the bacterial 16S rRNA gene sequence

Kawamura, Masaru; Hoshina, Takayuki; Ogawa, Masato; Yamamoto, Noboru; Haro, Kaoru; Kumadaki, Tokiko; Fukuda, Kazumasa; Kusuhara, Koichi

OBJECTIVES: The aim of this study is to determine the optimal duration of antimicrobial therapy for lower respiratory tract infection (LRTI) in neuromuscular disorder (NMD) patients. METHODS: This prospective study included 13 episodes from 9 NMD patients hospitalized for bacterial LRTI. Sputum samples were collected from these patients during the three consecutive days after their admission. Bacterial cell counts and the proportion of the most predominant bacterium identified by a clone library analysis of the bacterial 16S rRNA gene sequence in the samples obtained before antimicrobial therapy were serially investigated. RESULTS: All episodes were initially treated with ampicillin/sulbactam. In 12 episodes with a therapeutic effect, the bacterial cell counts in the samples obtained on the third day of therapy were significantly lower than those before therapy (P = 0.0013). In most of these episodes, the most predominant bacterium in the sample obtained before therapy was undetectable by the third day of therapy. In the one patient without a therapeutic effect, neither the bacterial cell counts nor the proportion of the most predominant bacterium in the sample obtained before therapy decrease after therapy. CONCLUSION: Short-term antimicrobial therapy is sufficiently effective for LRTI in NMD patients if the initial therapy is effective.