Sensitivity to beta-lactam antibiotics of isolates clinically obtained from respiratory infection sites in adults on the second survey on sensitivity of isolates conducted by the Japanese Society of Chemotherapy in 2007 was investigated according to the classification of the "Guideline for treatment for adult nosocomial pneumonia in 2008". Among the primary antibacterial drugs for mild (A) and moderate (B) nosocomial pneumonia in adults, beta-lactam antibiotics; ceftriaxone (CTRX), sulbactam/ampicillin (SBT/ABPC), panipenem/betamipron (PAPM/BP), tazobactam/piperacillin (TAZ/PIPC), imipenem/cilastatin (IPM/CS), meropenem (MEPM), doripenem (DRPM), biapenem (BIPM) were studied to evaluate their clinical efficacy. The covering rate was analyzed using the minimal inhibitory concentration (MIC) and break point of pharmacokinetics/pharmacodynamics (PK/PD). Consequently, the results with methicillin-susceptible Staphylococcus aureus (MSSA), Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis and Klebsiella pneumoniae revealed the MIC90 of all antibacterial drugs to be at low levels, while almost 100% of isolates were within the range of PK/PD break points except BIPM and SBT/ABPC to H. influenzae, and SBT/ABPC to K. pneumoniae. However, the analysis of P. aeruginosa didn't reach 100% for the covering rates of isolates, indicating that these drugs did not have a complete inhibitory action to restrict bacterial proliferation. The analysis of all 5 carbapenem drugs showed superiority to TAZ/PIPC in MIC90 while covering rates of isolates at PK/PD break points showed inferiority to TAZ/PIPC. This tendency was found to be more significant in covering the rates of isolates on the regular dose with maximal bactericidal action and on the maximum dose. This is because the maximum dose approved in Japan is as low as half that in IPM/CS and 1/3 that in MEPM in Western countries.