Penicillin-resistant pneumococci (PRSP) have been increasing recently in our hospital. The percentages of penicillin-resistant strains in isolated pneumococci were 38.5% in 1992, 33% in 1993 and 34% in 1994. We developed a new selective agar plate for PRSP (PRSP-SM). Briefly, we added oxacillin (0.1mg/I), aztreonam (10mg/l) and gentamicin (5mg/l) to Tripticase soy II agar supplemented with 5% sheep blood. In these agar plates, 100%(70/70) of PRP grew and 81%(91/112) of penicillin-sensitive pneumococci (PSSP) did not grow. However, some gram-negative rods (Pseudomonas aeruginosa, Pseudomonas cepacia, Serratia marcescens, Xanthomonas maltophilia) also grew. Antibiotics in the agar plates stored at 4ºC were active enough for 42 days (oxacillin) or 90 days (aztreonam, gentamicin). In these agar plates, PRSP in the clinical samples grew by overnight incubation, however major contaminant organisms, P.aeruginosa, Haemophilus influenzae, Staphylococcus aureus, Branhamella catarrhalis and PSSP almost never grow.

View full abstract

The present study was undertaken to investigate the effects of two synthetic penicillins, ampicillin (ABPC) and cloxacillin (MCIPC), on the contractile responses of isolated guinea pig vas deferens, which has smooth muscle that is under the control of sympathetic nerves. The effects of 6-aminopenicillanic acid (6-APA), the basic component of these penicillins, on contractile response were also investigated. It has been proposed that noradrenaline and adenosine triphosphate (ATP) are simultaneously released from sympathetic nerves in the vas deferens, and act as co-transmitters, while the isolated vas deferens evokes a contractile response by exogenously added noradrenaline as well as exogenously added ATP. ABPC (5×10^-4g/ml-2.5 × 10^-3g/ml) and 6-APA (5 ×10^-4 g/ml-2.5 × 10^-3g/ml) significantly increased the amplitude of the contractile responses induced by electrical nerve stimulation, while MCIPC (5× 10^-4g/ml-2.5× 10^-3g/ml) significantly decreased them. ABPC and 6-APA, each at the concentration of 2.5 × 10^-3g/ml, significantly increased the amplitude of the contractile responses induced by the three treatments, that is, electrical muscle stimulation, exogenously added noradrenaline and exogenously added ATP. However, MCIPC, at the same concentration, significantly decreased them. In the case of electrical nerve stimulation alone, the decrease in the amplitude of the contractile response caused by MCIPC was not completely eliminated even by washing with normal Krebs solution. These results led to the following conclusions: 1) ABPC and 6-APA may act directly on the intramural muscle of the vas deferens so as to increase the amplitude of the contractile response of its muscle and this increase in amplitude is not considered to be mediated via the effects of these agents on the intramural sympathetic nerves of the vas deferens. This increase is a special effect that has been not observed in other organs. 2) MCIPC may act mainly directly on the intramural muscle of the vas deferens so as to decrease the amplitude of the contractile response of its muscle, although the effect of this agent on the intramural sympathetic nerves of the vas deferens is unlikely to be completely negligible. 3) The difference between the effects of ABPC and MCIPC on the contractile response of the vas deferens may be attributable to the difference in the side chain connected to the basic structure of these agents.

View full abstract

We have studied the susceptibility of nine representative causative agents of respiratory track infection, that were isolated in our hospital, to several new quinolones: ofloxacin (OFLX), norfloxacin (NFLX), lomefloxacin (LFLX), ciprofloxacin (CPFX) and tosufloxacin (TFLX). Whether a bacterial strain was resistant or susceptible was assessed by all the break point criteria given by three authorities, namely, the Japan Society of Chemotherapy (JSC), the British Society for Antimicrobial Chemotherapy (BSAC) and the National Committee for Clinical Laboratory Standards (NCCLS). Since the break point values varied slightly, but were generally 1-2μg/ml, the results also varied according to the criteria. For example, the suscetibility rates of Streptococcus pneumoniae and Pseudomonas aeruginosa against CPFX, when judged by the JSC criteria, were higher than those judged by the other criteria. From assessing susceptibility with these criteria, we considered that there should be special attention given to two bacterial species, P. aeruginosa and Staphylococcus aureus, because their susceptibility rates, which were generally low against almost all drugs and approximately 20-30%, were much different from the others. The antibacterial effect of TFLX against S. pneumoniae was the most potent, followed by OFLX and CPFX, in that order. Judging by any criterion, and even considering the tissue distribution of the drugs, NFLX and LFLX were expected to have no effect clinically. However, the susceptibity rates of the other six bacterial species, excluding the three mentioned above, was determined to be generally over 80% by all criteria. We considered that clinical decision-making using break point criteria was satisfactory for the therapeutic use of new quinolones in respiratory tract infection, when the infections is caused by Moraxella catarrhalis, Haemophilus influenzae, Escherichia coli, Klebsiella pneumoniae, Enterobacter cloacae or Serratia marcescens.

View full abstract

Between July 1983 and May 1994, 752 episodes of infections that developed in patients with hematological disorders were treated with 12 regimens of initial antibacterial therapy. The regimens consisted of third-generation cephems or a broad-spectrum penicillin administrated as a monotherapy or in combination with amikacin, clindamycin, minocycline, or fosfomycin. Among 600 evaluable episodes, 389 had defervesced (overall efficacy rate, 65%). The efficacy rate for each infection was 59% for sepsis (41/69), 65% for suspected sepsis (267/408), 50% for pneumonia (24/48), 76% for lower respiratory infection (19/25), 80% for upper respiratory infection (4/5), 83% for urinary tract infections (19/23), 67% for phlegmon (6/9), and 69% for the other infections (9/13). One hundred and eighty-nine strains of bacteria were isolated from 147 episodes; among these, 93 were gram-positive and 96 were gram-negative. Clinically, 47% of gram-positive infections and 65% of gram-negative ones responded to the initial therapy (overall efficay rate, 56%). Among 189 isolates, 72 were from 69 episodes of sepsis; 41 were gram-positive and 31 were gram-negative. Clinical effect was observed in 51% of gram-positive bacterial sepsis and 74% of gram-negative (overall efficacy rate, 61%). The proportion of gram-positive bacteria was 37%(39/105) before 1990 and 64%(54/84) after 1991; the difference was significant (p<0.01). This was reflected by an increase in Staphylococcus epiderrnidis and a decrease in Pseudomonas aeruginosa; in addition, MRSA was isolated after 1991. The trend of isolates from sepsis was similar to that of all infections.

View full abstract