[Clinical and experimental research on some toothpastes]

Authors assayed in vitro 9 toothpastes (signed A to I) against 8 types of microorganisms. Toothpaste D yielded best results, toothpastes A and B shown no antibacterial power; the other ones had intermediate degrees of effectiveness. Authors also performed an in vivo study testing 3 toothpastes on to 5 healthy volunteers, but results are not statistically significant.

[Antibacterial activity of cefmenoxime against clinical isolates. Comparative study]

Antibacterial activity of cefmenoxime (CMX) against clinically isolated organisms was examined in comparison with that of 4 other antibiotics and concluded as follows: Antibacterial activity of CMX was markedly stronger than those of cefazolin (CEZ), cefmetazole, latamoxef and ampicillin against E. coli, K. pneumoniae, S. marcescens, H. influenzae, P. mirabilis and indole positive Proteus. But the MIC level of CMX against S. aureus was higher than that of CEZ.

Trends in bacterial susceptibility to antimicrobial agents

Concern over the development of drug resistance by common pathogens has grown over recent years. In order to discover and describe possible trends at this institution, susceptibility data for 18 organisms and 21 antimicrobial agents for the years 1975 through 1982 at the Veterans Administration Medical Center in Oklahoma City were reviewed. Summaries of susceptibility data for 64 major combinations of drugs and organisms are presented. Two gram-positive organisms (enterococcus group D and Staphylococcus aureus) as well as a gram-negative (Pseudomonas aeruginosa) appear to be decreasing in susceptibility to several drugs. However, some gram-negative bacilli (Proteus, Serratia, and Enterobacter spp. and Klebsiella pneumoniae) showed evidence of markedly increasing susceptibility to certain drugs.

Comparative in-vitro activity of quinolone carboxylic acids against Proteeae

The in-vitro susceptibilities of 198 isolates of precisely identified Proteeae species to six quinolone antimicrobials were determined. Significant differences in susceptibility patterns among various Proteeae to the quinolones examined were demonstrated. Although Providencia stuartii was found to be the most resistant to quinolones including the very active agent ciprofloxacin, fully speciated Prov. rettgeri were also markedly resistant as well. in contrast Prov. alcalifaciens was extremely sensitive to these agents. Some strains of Proteus penneri were more resistant to the three newer compounds (ciprofloxacin, enoxacin and norfloxacin) than strains of Pr. vulgaris suggesting that recognition of this species may be important in surveys of the in-vitro activity of antibiotics. Pr. mirabilis and Morganella morganii were very sensitive to the newer agents. The patterns of resistance seen in the three newer agents were reflected in the older agents acrosoxacin and cinoxacin. Accurate speciation of Proteeae in surveys of susceptibilities to antimicrobial agents is important if misleading results are not to be reported.

Research on antibacterial and antifungal agents. III. Synthesis of 1-ethyl-1,4-dihydro-4-oxo-7-(1-pyrryl)quinoline-3-carboxylic acid and of some 6-derivatives

A new analog of nalidixic acid, 1-ethyl-1,4-dihydro-4-oxo--7-(1-pyrryl)quinoline-3-carboxylic acid, is described. When tested against gram-positive and gram-negative bacteria this compound showed many significant activities and was more active than nalidixic, piromidic and pipemidic acids. On the contrary its 6-chloro- and 6-methylderivatives lack antimicrobial activities. All new compounds here described were synthesized by standard procedures via Gould-Jacobs reaction.

Susceptibilities of 45 clinical isolates of Proteus penneri

Patterns of susceptibility of 45 Proteus penneri clinical isolates to 14 antimicrobial agents were evaluated by a macrobroth dilution method. All strains were highly susceptible to ceftizoxime, ceftazidime, moxalactam, cefoxitin, gentamicin, tobramycin, netilmicin, and, with few exceptions, to amikacin, piperacillin, and cefoperazone. Most strains were susceptible to cefotaxime and ceftriaxone. All strains were resistant to cefazolin and cefsulodin.

Comparison of antibiotic susceptibility results obtained with Adatab and disc methods

Strains of Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, faecal streptococci, Proteus spp, and Klebsiella spp were distributed on two occasions to two groups of laboratories, one using a commercially produced break point method (Adatab, Mast Laboratories Ltd) and the other using a disc method for susceptibility testing. Minimum inhibitory concentrations of a range of antibiotics were determined for each of the strains in the Division of Microbiological Reagents and Quality Control and a correct result of sensitive or resistant was assigned where possible to each combination of strain and antibiotic. Laboratories were asked to determine the susceptibility of the strains to those antibiotics that they would test in routine practice. Results from each laboratory were compared with the correct results. The overall error rates obtained with the Adatab and disc methods, 8% and 8.2% respectively, were not significantly different. Fewer errors were made with trimethoprim, ticarcillin, and nitrofurantoin by laboratories using Adatabs than those using discs. Fewer errors were made with gentamicin by laboratories using discs than those using Adatabs. There was no significant difference between the two groups of laboratories in reproducibility of results on repeated testing of the same strains. Laboratories using Adatabs used a wide range of different break point concentrations. The Adatab method appeared to offer no overall advantages in terms of reduced error rates or increased reproducibility of results with the strains tested.

Penetration of ceftazidime in human pericardial fluid and lung tissue

The penetration of ceftazidime in pericardial fluid and lung tissue was investigated in 14 thoracotomized patients, who had normal renal function and did not receive any antibiotic treatment before thoracotomy. The drug (28 mg/kg) was given by i.v. Blood, pericardial fluid and lung tissue samples were taken over the next 5 hours. Concentrations of ceftazidime in the lung tissue were very high in the first hour and over the 200 and 300 min time interval, the ratio between serum and lung tissue levels was 0.7. The correlation coefficient between pericardial fluid, serum ratio and time was calculated to be of 0.99 (P less than 0.001). From these data we can observe that ceftazidime rapidly diffuses into the pericardial space and lung tissue where good concentrations (5.4 mcg/g) persist for at least 5 hours.

Comparison of in vitro antibacterial activity of four oral cephems: cephalexin, cefaclor, cefatrizine and cefadroxil

The in vitro antibacterial activity of four oral cephems: cephalexin, cefaclor, cefatrizine and cefadroxil against clinical isolates of staphylococci, Enterobacteriaceae and Pseudomonas aeruginosa was compared by agar dilution method. All drugs had comparable antistaphylococcal activity. Cefatrizine and cefaclor were more active than cephalexin and cefadroxil against Escherichia coli, Klebsiella pneumoniae and Proteus mirabilis. All four drugs were relatively inactive against isolates of Enterobacter species and indole-positive Proteus. However, cefatrizine demonstrated the greatest activity of the four oral cephems against these organisms. None of these oral cephems was active against Serratia marcescens or Pseudomonas aeruginosa.

Researches on antibacterial and antifungal agents. II - Synthesis of 1-ethyl-1,4-dihydro-4-oxo-7-(1-pyrrolidinyl)quinoline-3-carboxylic acid, a novel highly active, broad-spectrum antibacterial agent related to piromidic acid

The synthesis and antibacterial activities of 1-ethyl-1,4-dihydro-4-oxo-7-(1-pyrrolidinyl)quinoline-3-carboxylic acid are reported. The new analog of nalidixic acid has been prepared by standard procedure starting from 1-(3-aminophenyl)pyrrole; it showed a broad spectrum of antibacterial activity and exhibited much higher activity than nalidixic, pipemidic and piromidic acids. The synthesis of 1-ethyl-1,4-dihydro-4-oxo-8-(1-pyrrolyl)quinoline-3-carboxylic acid is also described; this acid was inactive when tested as antibacterial agent.

[Pretreatment before microsurgical interventions in the middle ear with reference to the current bacteriological and antibiotic situation]

Swabs were taken from 100 patients suffering from chronic otitis media or mastoiditis before operation to identify bacteria and their sensitivity to antibiotics. Recommendations are made concerning local or general preoperative treatment.

A microbiological evaluation of apalcillin

The in vitro activity of apalcillin was tested against 350 clinical isolates of Escherichia coli, Enterobacter, Klebsiella, Proteus, Pseudomonas aeruginosa and Streptococcus faecalis. Using a minimal inhibitory concentration of 16 mg/l as the breakpoint, only 19.7% of the strains were resistant to apalcillin. A regression analysis demonstrated that it is possible to test bacteria for sensitivity with a 20 micrograms apalcillin disc. The results on Mueller-Hinton agar are very similar to those on Iso-Sensitest medium. Like other ureido penicillins, apalcillin is sensitive to most beta-lactamases; it is effective against ampicillin-resistant strains since it penetrates the outer membrane of gram-negative bacteria well and is highly effective against target proteins. Strains producing high amounts of beta-lactamases do become resistant to apalcillin.

A note on the determination of antibiotic susceptibility of invasive strains of Proteus by a simple agar dilution method

A method is described for testing antibiotic susceptibility of invasive and noninvasive micro-organisms in which strains are grown on small agar discs.

[Piperacillin: microbiological and clinical studies]

A microbiological and clinical study of the action of piperacillin is presented. The drug showed an excellent in vitro antibacterial action on gram positive and gram negative microorganisms. Its in vitro action on Ps. aeruginosa (70.8% of strains inhibited) was also extremely interesting, making it the second most effective of the antibiotics tested after polymyxin B and colistin, polypeptides unsuitable for clinical use. In vivo, the administration of piperacillin achieved a clinical and bacteriological cure in 35 out of 40 patients and a clinical cure in 2 out of 40. It was only therapeutically unsuccessful in 3 cases. It is concluded that its microbiological, kinetic and tolerance features make piperacillin suitable for a wide range of therapeutic purposes.

In vitro antibacterial activity of norfloxacin compared with eight other antimicrobial agents

The antibacterial activity of norfloxacin, an organic acid structurally related to nalidixic acid, was compared with that of the oral cephalosporins cefaclor and cephalexin, and with that of nalidixic acid, cinoxacin, amikacin, ampicillin, trimethoprim alone and the combination of trimethoprim and sulfamethoxazole. Agar dilution studies were performed with a total of 398 clinical isolates of gram-negative bacteria. Norfloxacin was found to be the most active drug studied against each of the different groups of organisms tested. MIC90 values for norfloxacin were as follows: Citrobacter spp., 2 micrograms/ml; Enterobacter spp., 0.13 micrograms/ml; Escherichia coli, 0.06 micrograms/ml; Klebsiella spp., 0.13 micrograms/ml; Proteus spp., 0.06 micrograms/ml; Salmonella spp., 1 microgram/ml; Serratia spp., 0.13 micrograms/ml; and Pseudomonas spp., 2 micrograms/ml. MIC90 values for the other drugs were 4 micrograms/ml or greater and many organisms were totally resistant to one or more of the other drugs (MIC greater than 128 micrograms/ml). Cross resistance between norfloxacin and the related drugs nalidixic acid and cinoxacin was not observed.

[Comparison of antibacterial potencies of oral and parenteral antibiotic preparations against Escherichia coli, Klebsiella, Citrobacter, and Proteus isolated from urinary tract infections (3. 1981). 3. Patient backgrounds and bacterial sensitivities]

Routine susceptibilities testing of microorganisms isolated from patients are of restricted usefulness in the treatment of patients because of the delay in obtaining results. Thus, the empiric chemotherapy based on the susceptibility of microorganisms isolated from patients is necessary for the majority of patients with simple and complicated urinary tract infections. In this study the relation between changing susceptibility and background factors such as age, a sex distinction, antibiotics, areas in Japan, simple and complicated UTI and so on, has been investigated.

[Comparison of antibacterial potencies of oral and parenteral antibiotic preparations against Escherichia coli, Klebsiella, Citrobacter, and Proteus isolated from urinary tract infections (3: 1981). 2. Changes in bacterial sensitivities]

Since 1979 the antibacterial activity of antibiotics against E. coli, Klebsiella, Citrobacter and Proteus isolated from patients with urinary tract infections has been investigated. The serious transition of susceptibilities of E. coli and Klebsiella could not be recognized in these antibiotics (MPC, ABPC, NA, PPA, CEX, CEZ, CTM, CMZ and CFX). However, a few resistant organisms against the third generation's antibiotics (CTX, CMX, CZX, LMOX and CPZ) have already been appeared, we have to observe these results, continuously.

[Comparison of antibacterial potencies of oral and parenteral antibiotic preparations against Escherichia coli, Klebsiella, Citrobacter, and Proteus isolated from urinary tract infections (3: 1981) 1. Susceptibility distribution]

In vitro activities of antibacterial agents against E. coli, Klebsiella, Citrobacter and Proteus which were isolated from patients with urinary tract infections at 8 hospitals in Japan, were investigated by dilution broth method using MIC 2000 (Dynatec) during July to October in 1981. The summarized results are as follows: Among oral antibacterial agents, MPC and PPA have showed potent antibacterial activities against E. coli and Klebsiella. In vitro activities of oral antibacterial agents against Proteus and Citrobacter showed not so potent. Among the first and second generation's parenteral antibacterial agents, CTM has showed potent antibacterial activities against E. coli and Klebsiella. Among the third generation's parenteral antibacterial agents, CMX, CTX and CZX have showed potent antibacterial activities against E. coli, Klebsiella, Proteus and Citrobacter.

[Quantitative relationships between various representatives of gastrointestinal microflora of experimental animals (rats) in normal conditions and after immunosuppression with imuran]

The influence of imuran (an analog of nitrogen ioprin) on the quantitative relationship between lactobacilli, bifidobacteria, bacteroids and aerobic autoflora in different sections of the gastrointestinal tract of white rats was studied under experimental conditions. On days 7-14-30 after the introduction of imuran into the gastrointestinal tract dysbacteriosis developed; it was characterized by a decrease in the number of lactobacilli and asporogenic anaerobic microflora and an increase in the number of aerobic microorganisms. By days 60-90 the content of aerobic microbes in all sections of the gastrointestinal tract was still elevated, while the rapid restoration of the number of bacteroids took place. Therefore, immunosuppression therapy with imuran may give rise to autoinfectious complications caused by different representatives of infective microflora.

Comparative in vitro activity of semisynthetic penicillins against Proteeae

The in vitro susceptibilities of 181 isolates of precisely identified Proteeae species to five semisynthetic penicillins were determined with low and high inocula. Significant differences in susceptibility patterns among various Proteeae species to the penicillins examined were demonstrated. Providencia stuartii was clearly distinguished from Providencia alcalifaciens by its greater resistance to the antibiotics tested.

Synthesis and antibacterial activity of 6- and 7-[2-(5-carboxyimidazole-4-carboxamido)phenylacetamido]-penicillins and cephalosporins

The synthesis and antibacterial activity of a series of beta-lactam antibiotics having a 5-carboxyimidazole-4-carbonyl group attached through an amide linkage to ampicillin, cephaloglycin or their analogs are described. Some compounds of this series were found to possess high activity against Pseudomonas and other Gram-negative bacteria.

[The antibacterial activity of new cephem antibiotics against clinical isolates. A comparison of the antibacterial activity of cefotaxime with 6 other antibiotics]

During the period from May through July 1981, a comparative study was carried out on the antibacterial activities of cefotaxime (CTX) and ceftizoxime (CZX), cefoperazone (CPZ), latamoxef (LMOX), cefotiam (CTM), cefmetazole (CMZ) and cefazolin (CEZ). CTX and these other cephem antibiotics were tested against fresh clinical isolates which had been obtained from clinical materials by the laboratories of 14 participating medical institutions. 1. The clinical isolates were obtained from various clinical materials in the following decreasing order: urine, sputum and pus/discharge; 85.7% of the isolates came from these materials. 2. Concerning the sources of each species of clinical isolates, it was found that P. aeruginosa was isolated from the greatest number -9- of different clinical materials. This was followed by E. coli and E. cloacae, each isolated from 8 different clinical materials, and C. freundii and E. aerogenes, each found in 7 different clinical materials. 3. In relation to S. pyogenes, S. agalactiae and S. pneumoniae, CTX showed the best antibacterial activity; the second most potent antibiotic was CZX. CMZ and LMOX were found to show relatively high MIC values for those species. Against S. aureus, CEZ showed the best antibacterial activity, but 3 resistant strains had MICs of greater than 100 micrograms/ml. 4. With regard to Gram-negative bacteria, CTX and CZX showed the best antibacterial activities for all of the species, except for P. aeruginosa. These were followed, in order, by LMOX and CPZ. Compared with these 4 antibiotics, CTM, CMZ and CEZ were found to have inferior antibacterial activities against these bacteria. In relation to P. aeruginosa, the peak of the MIC distribution for CPZ was 6.25 micrograms/ml, and this was the best antibacterial activity detected with the various antibiotics tested. This was followed by CTX (25 micrograms/ml) LMOX (25 micrograms/ml) and CZX (50 micrograms/ml). CTM had an MIC of 100 micrograms/ml for 1 strain, and MICs of greater than 100 micrograms/ml for all of the other strains of P. aeruginosa, indicating them to be resistant to this antibiotic. All of the strains were resistant to CMZ and CEZ, showing MICs of greater than 100 micrograms/ml. 5. For each of the tested antibiotics, no correlation was found between the MIC and the serogroup for either P. aeruginosa or S. marcescens.

Cefoxitin, N-formimidoyl thienamycin, clavulanic acid, and penicillanic acid sulfone as suicide inhibitors for different types of beta-lactamases produced by gram-negative bacteria

Cefoxitin, N-formimidoyl thienamycin (MK0787), clavulanic acid, and penicillanic acid sulfone (CP45,899) were studied to determine their potency as suicide inhibitors of three very different kinds of beta-lactamases produced by Gram-negative bacteria: type Ib penicillinase (TEM-2 type), a typical cephalosporinase (the enzyme of Proteus morganii), and a cephalosporinase with broad substrate specificity (the enzyme of Proteus vulgaris). All these beta-lactams were confirmed to be quite stable to the three beta-lactamases. The absolute values of the turnover numbers (kcat) for these enzyme-catalyzed hydrolyses were determined, the values ranged from 0.25 minute-1 to 660 minute-1. All the beta-lactams studied, except cefoxitin, acted as suicide inhibitors of the typical cephalosporinase. Although cefoxitin did not exhibit such an effect, it was a powerful competitive inhibitor of this enzyme. Although the four beta-lactams acted as suicide inhibitors of the P. vulgaris cephalosporinase, the inactivated enzyme partially regained its activity after removing the effect of the free inhibitor. Type Ib penicillinase was also inactivated by the four beta-lactams, and the activity of the inactivated enzyme, except in the case of cefoxitin, was partially restored. The rate constants for enzyme inactivation or reactivation were calculated and are presented. The information obtained from this study suggests that the catalytic center of the P. vulgaris cephalosporinase is different not only from that of the penicillinase-type but also from that of the cephalosporinase-type beta-lactamases.

Correlation of beta-lactamase production and resistance to beta-lactam antibiotics in Enterobacteriaceae

Incidence of beta-lactamase production (using the Nitrocefin test and isoelectric focusing) was evaluated on 284 strains of ampicillin-resistant Enterobacteriaceae. Production of the various beta-lactamases was correlated with the resistance to different beta-lactam antibiotics. No obvious correlation between the beta-lactamase production and the resistance pattern was found. The most striking result was the lack of beta-lactamase production in 42.6% of the strains. About 50% or more of the Proteus morganii, Proteus vulgaris, Serratia and Enterobacter strains produced no beta-lactamases, in contrast to E. coli, Klebsiella, and Proteus rettgeri strains which produced beta-lactamases extensively. The predominant enzyme was TEM 1, while TEM 2 enzyme was extremely common in Proteus mirabilis and Proteus rettgeri. Finally, it can be concluded from our results that the production of beta-lactamases can be regarded as an important but not the sole determinant of resistance of beta-lactam antibiotics.

In vitro activity of temocillin, a new beta-lactamase-stable penicillin active against enterobacteria

The activity of temocillin was investigated in vitro against 523 clinical isolates of enterobacteria and Pseudomonas aeruginosa. The minimum inhibitory concentration of the new compound for all ampicillin-susceptible enterobacteria and for 90% of ampicillin-resistant enterobacteria was 16 micrograms/ml or less, a concentration readily achieved in plasma. P. aeruginosa strains were uniformly resistant to temocillin. All but 3 of a separate group of 48 enterobacteria exhibiting resistance to the combination of clavulanic acid and amoxicillin were found to be inhibited by 16 micrograms or less of temocillin per ml. The new compound also displayed good activity against a group of laboratory stock cultures selected on the basis of differential resistance to presently available beta-lactam agents. Two of these strains were cefotaxime resistant.

In vitro antibacterial activity of E-0702, a new semisynthetic cephalosporin

E-0702 is an antipseudomonal cephalosporin derivative which has a broad spectrum of antibacterial activity against clinical isolates of gram-positive and gram-negative bacteria. Its in vitro antibacterial activities were less than those of cefoperazone and cefotaxime against Staphylococcus aureus and Staphylococcus epidermidis, but were significantly high against gram-negative bacteria including the Pseudomonas group. It was most characteristic that E-0702 showed high antibacterial activity against Pseudomonas aeruginosa. E-0702 was relatively stable to inactivation by plasmid-mediated penicillinases and cephalosporinases produced by gram-negative bacteria.

Interaction of mezlocillin and cefoxitin against Proteus morganii in the granuloma pouch model

The interaction of cefoxitin and mezlocillin was studied in rats using the granuloma pouch technique. Proteus morganii strains against which cefoxitin and penicillins exhibited antagonistic antibacterial activity were selected for infection of the pouches. Animals were treated with cefoxitin and/or mezlocillin, and bacterial counts, drug levels and beta-lactamase production in the pouch exudate monitored. A significant decrease in bacterial counts was seen after administration of mezlocillin and cefoxitin in combination but not after the drugs administered alone. Drug concentrations of mezlocillin and/or cefoxitin corresponded directly to the rate of induction of beta-lactamase activity. Although both beta-lactam antibiotics induce beta-lactamase activity, administered in combination in vivo they appear to protect each other from being inactivated thus resulting in synergistic antibacterial activity.

Species differences in susceptibilities of Proteeae spp. to six cephalosporins and three aminoglycosides

Six cephalosporins and three aminoglycosides were examined for activity against 1,693 isolates belonging to six species of Proteeae. The most notable species-specific differences included the marked susceptibility of Providencia alcalifaciens and Proteus mirabilis to cephalothin, the resistance of Proteus vulgaris to cefamandole, and the resistance of Providencia stuartii to gentamicin and tobramycin. The third-generation cephalosporins cefotaxime and moxalactam were substantially more inhibitory than were cefoperazone, cefamandole, and cefoxitin. P. stuartii, generally the most resistant species, was, however, markedly susceptible to moxalactam and cefotaxime.

[Clinical and experimental study of dioxidine. Its antibacterial action]

The effect of dioxidine on the growth of freshly isolated clinical strains of microorganisms with various levels of resistance to antibiotics was studied. It was shown that strains of Ps.aeruginosa not resistant to carbenicillin, chloramphenicol and nalidixic acid were most sensitive to the drug. Similar correlation was found in Proteus strains with various levels of resistance to chloramphenicol. Sensitivity of these organisms to dioxidine did not depend on their resistance to gentamicin, ampicillin and neomycin. The antibacterial effect of the drug is based on inhibition of the synthesis of nucleic acids, the level of DNA synthesis inhibition being the highest. Dioxidine had practically no effect on protein synthesis.

[The value of fosfomycin]

After description of the most important properties of fosfomycin including pharmacokinetics, antibacterial activity and hitherto got clinical experiences the determinations of the resistance on frequent clinical pathogenic agents are reported. They were performed in the diffusion test in a platelet content of 20 micrograms with admixture of glucose-6-phosphate. High sensitivity rates showed E. coli, P. mirabilis, hemophiliacs and above all Staph. aureus, but also a large part of the Klebsiella and the Pseudomonas strains could be classified as sensitive. Streptococci, pneumococci and enterococci mostly proved as resistant. Thus, in an oral therapy the spectre is smaller than in a highly dosed parenteral supply. Nevertheless, fosfomycin in the two forms of application is to be regarded as an enrichment of the therapeutic possibilities and further should be tested clinically.

[Compared studies of antimicrobial agents against E. coli, Klebsiella, Citrobacter and Proteus isolated from urinary tract infections]

In vitro activities of antibacterial agents against E. coli, Klebsiella, Citrobacter and Proteus which were isolated from patients urinary tract infections at 8 hospitals in Japan, were investigated by agar dilution method from July to October in 1979. The summarized results are as follows. 1. Among oral antibacterial agents, MPC and PPA have showed potent antibacterial activities against E. coli and Klebsiella. Among parenteral antibiotics, CTM was the most active against E. coli and Klebsiella. However, ABPC-resistant E. coli and Klebsiella have appeared to occupy about 40% and 96% of bacteria isolated from urinary tract infections, respectively. 2. In vitro activities of antibacterial agents against Proteus and Citrobacter showed not so potent. 3. Causative organisms in female patients with simple urinary tract infections were mainly E. coli and Klebsiella. 4. Among oral antibacterial agents, PPA have shown similar antimicrobial activities against E. coli isolated from simple and complicated urinary tract infections. ABPC and MPC have been influenced in some degree by these factors. However, parenteral antibiotics are not influenced by these factors. On the other hand, in vitro activities of antibacterial agents against Klebsiella isolated from simple and complicated urinary tract infections were similar.

[Rapid determination of the minimal inhibitory concentration of an antibiotic by measuring bacterial ATP (author's transl)]

The minimal inhibitory concentrations (MIC) of gentamicin for ten strains of Enterobacteriaceae were determined by measuring the bacterial ATP (adenosine triphosphate). ATP was measured by chemiluminescence on 4-h growth cultures which included gentamicin. The MIC results obtained by this method were equivalent to those found with the technique of dilution in liquid medium.

Penetration of cephalosporins and corresponding 1-oxacephalosporins through the outer layer of Gram-negative bacteria and its contribution to antibacterial activity

1-Oxacephalosporins had a higher ability to penetrate through the outer layer of the envelope of gram-negative bacteria than the corresponding cephalosporins. In spite of the liability of 1-oxa congeners to beta-lactamases, they attained higher periplasm concentrations at a given concentration outside the cells. The replacement of sulfur in the cephem nucleus by oxygen was accompanied by an increment of the hydrophilic character of the molecule, which suggests that this character was favorable for outer layer penetration. 1-Oxacephalosporins showed enhanced antibacterial activity in short-term measurement and exerted their antibacterial action at lower periplasm concentrations. Thus, the enhanced antibacterial activity of 1-oxacephalosporins seems to be due to their higher penetrability and their intrinsic inhibitory activity against the peptidoglycan biosynthesis system.

Colonial variants of proteus species: their growth requirements, biochemical characters and resistance to antibacterial agents

Stable small-colony variants of Proteus species were isolated and characterised. They differed from typical organisms in their morphology, biochemical properties and drug resistance. They were found most frequently in culture media of low osmolarity. Their growth rate was depressed at high concentrations of salts, which had only a small effect on typical organisms. This may be important in the routine isolation of proteus spp. and in testing of disinfectants.