Antimicrobial activities of meropenem (MEPM), imipenem (IPM), panipenem (PAPM), ceftazidime (CAZ), cefozopran (CZOP), aztreonam (AZT), norfloxacin (NFLX) and tetracycline (TC) against clinically isolated Gram-negative bacilli [271 strains of Enterobacteriaceae and 242 strains non-fermentative Gram-negative bacteria (NFB)] were investigated.
Among carbapenem antibiotics, MEPM showed the lowest MIC₉₀, which activity was about four-hold higher than those of IPM and PAPM. The activity of IPM was equal or slightly superior to that of PAPM.
Resistance to IPM (>16μg/ml) was observed in 3 strains of Enterobacteriaceae (1.1%) and 14 strains of NFB (5.8%). It is conceivable that these strains produce metallo-β-lactamase.
Referring to the correlation among MICs of MEPM, IPM and PAPM, 3 strains in 3 species of Enterobacteriaceae showed cross resistance to carbapenems ; while 14 strains of NFB showed cross resistance to MEPM and IPM, 15 strains to MEPM and PAPM, and 29 strains to IPM and PAPM, and all of these strains were Pseudomonas aeruginosa. Fifteen of 29 strains of IPM-resistant and 77 of 92 strains of PAPM-resistant P aeruginosa were susceptible to MEPM.
Thirty-three strains (12%) of the Enterobacteriaceae were resistant to CAZ and AZT (≥32μg/ml) and these were considered as ESBL-producing strains.

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In order to evaluate the annual changes of susceptibility, minimum inhibitory concentrations (MICs) of ofloxacin (OFLX) and 4 control drugs were determined against clinical isolates that were obtained from patients with otitis media and otitis externa during the periods between January and December 1993, and the periods between October 1996 and March 1997.
The results are summarized as follows;
1. No annual changes were seen for MIC₅₀ of OFLX, but MIC₈₀, and MIC₉₀ of that rose against methicillinresistant Staphylococcus aureus (MRSA), coagulase-negative staphylococci (CNS) and Pseudomonas aeruginosa from 1993 to 1996.
It appears that resistance to OFLX is increasing among these bacteria.
Detection frequency of highly resistant strains to OFLX (MIC>100μg/ml) was lower than that to other control drugs.
2. No annual changes were seen of MIC₅₀, MIC₈₀ and MIC₉₀ of OFLX against methicillin-susceptible S. aureus (MSSA), Streptococcus spp., Proteus spp. and Haemophilus influenzae.
OFLX showed strong antimicrobial activities against these bacteria.
3. Since there was no large annual changes in the antimicrobial activity of OFLX against clinical isolates that were obtained from patients with otitis media and otitis externa, OFLX otic solution was considered as one of the clinically useful drugs even now.

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Cytokines are known to increase in the patients subjected to open chest surgery. Those patients are usually administered with antibiotic agents for prophylaxis, while some of antibiotic agents might yield significantly higher level of cytokines than other agents especially in patients suffering from severe infections.
It is believed that imipenem may yield lower interleukin-6 (IL6) level than cephem antibiotics. To study whether such difference could be observed in the patients who show no sign of severe infections, a total of 13 patients underwent scheduled open chest surgery were allocated at random into two groups, the imipenem-group and the flomoxef-group. The cytokine levels of the patients in the two groups were compared, while the prophylactic administration of imipenem or flomoxef.
In both groups, IL6 increased immediately after the operation while endotoxin remained unchanged. Thereafter IL6 decreased gradually in both groups, however, the decrease of IL6 in the imipenem-group was faster andgreater than the flomoxef-group resulting in the significantly lower level of IL6 on the 4th day after operation.One week after the operation, there existed no difference in the IL6 levels between these two groups.
In conclusion, it was suggested that, depending on the choice of a prophylactic antibiotic agent, some invasive burden could be added to those patients underwent open chest surgery, a certain number of whom would develop severe infection.

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