Inhibition by 6-O-tosyl galactosides of beta-galactoside phosphorylation and transport by the lactose phosphotransferase system of Staphylococcus aureus

The effect of various galactose derivatives, substituted at C-6, on the phosphoenolpyruvate:beta-galactoside phosphotransferase system of Staphylococcus aureus was studied. Cells were grown by an improved procedure, which resulted in a 5- to 10-fold increase in cell yield. The four protein components of the system were separated. A membrane fraction containing negligible levels of the soluble components was prepared by alternate cycles of sonic treatment and differential centrifugation. The in vitro system reconstituted from these fractions was used to test the ability of the galactose derivatives to inhibit the phosphorylation of lactose analogs, under conditions where the membrane-bound component, Enzyme IIlac, was rate limiting. Derivaites in which the hydroxyl group of C-6 was missing, or replaced by a fluoro, O-methyl, or carboxyl group had no affinity for Enzyme IIlac, as judged by their inability to inhibit phosphorylation. Surprisingly, derivatives containing arylsulfonyl groups at C-6 were potent inhibitors; the O-tosyl compound has an apparent affinity five times that of galactose. The arylsulfonyl substitution in an absolute requirement; neither O-benzyl or O-methanesulfonyl derivatives were inhibitory. The specificity of the inhibition by tosyl derivatives parallels that of unsubstituted substrates; tosyl galactosides of the beta configuration were inhibitory, but those of the alpha configuration were not. The tosyl derivatives also strongly inhibited the uptake of lactose analogs into whole cells; the requirement for the arylsulfonyl moiety was again observed. The chemical analogy between the tosyl galactosides and possible intermediates in the transport-phosphorylation step catalyzed by Enzyme IIlac provides a possible explanation for the unexpected properties of these derivatives.

[Bactericidal activity of serum and chemotherapy in sensitive and resistant exciter (author's transl)]

Comparing examinations with Ampicillin sensitive and resistant bacteria-strains show that the bactericidal activity of serum is dependent on the bacteria-strains, on the Ampicillin sensitivity of the particular exciter and on the number of bacteria/ml (germ count). Bactericide effect could always be obtained with sensitive strains as a result of additional chemotherapy. With several resistant strains a bactericide effect could not be obtained in this case the continuous optimal Ampicillin addition was the decisive factor. Because of the extremely complicated process of the bactericide one should not make general conclusions from the individual experimental results.

Nanaomycins, new antibiotics produced by a strain of Streptomyces. I. Taxonomy, isolation, characterization and biological properties

Nanomycins are new antibiotics produced by the strain OS-3966 which was designated Streptomyces rosa var. notoensis. Nanomycins A and B were isolated from the culture filtrate by extraction with organic solvent and silica gel chromatography. The physical and chemical properties suggest that nanaomycins A and B are quinone-related compounds having the molecular formulae, C16H14O6 and C16H16O7, respectively. Nanaomycins A and B inhibit mainly mycoplasmas, fungi and Gram-positive bacteria. The acute toxicities (LD50, ip) of nanaomycins A and B in mice are 28.2 and 169 mg/kg, respectively.

Potential biologically active agents. IX. Synthesis of N-piperidino-(morpholino)-methylisatin-3-anils

Sixteen N-piperidino-(morpholino)-methylisatin-3-anils have been synthesised and evaluated for their antimicrobial activity.

[The action of acridine derivatives on penicillinase production by staphylococcus aureus]

A study was made of a possibility of inhibition of biosynthesis of penicillinase in Staph. aureus by acridine derivatives. Acetone preparations of penicillinase were obtained from the cultures of staphylococcus strains 16/160 and 8325 (p11(147) pen 1220) grown in the presence of various subbacterial concentrations of acridine derivatives. The activity of the enzyme was studied in experiment and control by the microiodometric method. Acriflavine and proflavine inhibited the penicillinase biosynthesis from the 4th hour of growth, and rivanol, acrichine, acridines No. 27 and 37--from the 12th hour of the culture growth.

Recombinant plasmid obtained from two different, compatible staphylococcal plasmids

From two different, compatible staphylococcal plasmids that determine streptomycin and chloramphenicol resistance, respectively, a recombinant plasmid was obtained. This plasmid can be transduced with a rather high frequency (10(-4)/plaque-forming unit) to plasmid-negative strains, the linkage of the two markers being 100%. The maintenance of the recombinant plasmid in the host cell seems to be controlled by the chloramphenicol resistance plasmid. The recombinant plasmid proved to be incompatible with both parental plasmids, which are unrelated. The relationship between the chloramphenicol resistance plasmid and the recombinant plasmid was the same as the between genetically marked derivatives of the recombinant plasmid, whereas the relationship of the streptomycin resistance plasmid to the recombinant plasmid was of a different, asymmetrical type.

Staphylococcus aureus-strains of phage group II and their possible relation to animal staphylococci. 1. Antigenic properties, phage typing, and resistance to antibiotics

Investigations carried out on 350 strains isolated from clinical materials and carriers revealed that among coagulase-positive staphylococci of phage group II two main serologic types predominated. The first (61,1%) was characterised by positive reaction with factor serum 263-2, the second (30,8%) one gave positive reaction with factor serum i1-2. The strains of type 263-2 contained as a rule polysaccharide A as well as polysaccharide 263, contrary to staphylococci belonging to type i1-2 which possessed polysaccharide A only. Both serologic types differed also epidemiologically, in phage typing and resistance to antibiotics. Staphylococci of serologic type 263-2 occurred in neraly all purulent lesions, they were more resistant to antibiotics than type i1-2 and prevailed in hospital environments. In phage-typing the differences between both serologic types were quantitative in character, with two being most outstanding, namely the prevalence of strains sensitive to phage 71 among staphylococci of serologic type 263-2 and of phage types 3A, and 3C as well as 3A, 3B, 3C among staphylococci of serologic type i1-2. There was no correlation between the susceptibility of strains to phage 71 and their virulence, the latter seemed to be connected with serologic type.

[Effect of biologically active compounds on the resistance of bacteria to antibiotics]

A number of biologically active substances, i. e. main protamine proteins and histones, EDTA, lysozyme, methacyl and pentoxyl was studied with respect to their effect on the levels of the minimum inhibitory concentrations of antibiotics against E. coli and Staph. aureus and transfer of resistence to chloramphenicol in E. coli on conjugation. It was shown that the above substances lowered the minimum inhibitory concentrations of the antibiotics 2--10 times when added to the culture simultaneously with the latter. The results varied depending on the strain and the resistance nature. Marked inhibition of transfer of resistance to chloramphenicol in the presence of the main proteins and EDTA was found.

Detection of temperature-sensitive tetracycline resistance plasmids in Staphylococcus aureus

A method is described for the detection of temperature-sensitive plasmids determining tetracycline resistance in Staphylococcus aureus. Temperature-sensitive plasmids were detected in phage group I strains but not in phage group III strains.

Susceptibility of clinical isolates of Staphylococcus aureus to killing by oxacillin

Sixty clinical isolates of Staphylococcus aureus have been screened for their relative susceptibility to the killing action of oxacillin. Only one of these strains was found to be exceptionally resistant to the bactericidal effect of this and other beta-lactam antibiotics. This ability to survive oxacillin inhibition of cell wall synthesis has been called "tolerance". The characteristics of the tolerant organism, which has been designated the Evans strain, in comparison with other isolates of S. aureus indicate that this form of resistance is not apparent from the minimal inhibitory concentration, is not related to an abnormal growth rate, and can be enhanced by treatment with N-methyl-N'-nitro-N-nitrosoguanidine.

Synthesis and antitumor activity of 2-deamino- and N2-(gamma-hydroxypropyl)actinomycin D

2-Deamino- and N2-(gamma-hydroxypropyl)actinomycin D were synthesized by modification of the parent actinomycin D molecule at the 2 position of the phenoxazinone moiety. The common intermediate was 2-deamino-2-chloroactinomycin D. Catalytic hydrogenation of this material afforded the 2-deamino derivative while treatment with gamma-hydroxypropylamine yielded the N2-(gamma-hydroxypropyl) derivative. These 2-substituted actinomycin D derivatives were less potent in microbiological assays than the parent compound. Evaluation of activity in vivo against three murine tumor systems indicated that optimal dose levels of 2-deaminoactinomydin D were 50 times greater than toxic dose levels of actinomycin D. N2-(gamma-hydroxyporpyl)actinomycin D exhibited antitumor activity similar to the parent compound.

The antimicrobial properties of povidone-iodine methylmethacrylate complex. A preliminary report

The incorporation of povidone-iodine into polymethylmethacrylate was found to inhibit the growth of coagulase-positive Staphylococcus aureus in vitro.

[Resistance of different strains of pathogenic staphylococcus to unfavorable environmental factors]

A study was made of the resistance to drying the UV-irradiation, the action of furacillin and chloramine displayed by 60 stains of S. aureus differing by origin (hospital and extrahospital), by the source of discharge (the upper respiratory tracts of carriers and the discharge of the purulent-inflammatory foci of surgical patients), relation to the antibiotics (polyresistant and sensitive) and phage-group reference. It was found that the resistance of staphylococci to the unfavourable factors was not always associated with the listed signs of the strains. In respect to drying a marked resistance was expressed by the hospital strains in comparison with the extrahospital ones, polyresistant in comparison with the sensitive ones, staphylococci of III and I+III phage groups in comparison with the strains of other bacteriophage groups. Strains of the III phage group proved to be the most resistant to the UV-irradiation. Strains isolated from carriers were more resistant to furacillin than staphylococci isolated from the purulent-inflammatory foci. Strains of the III phage group and nontyping had analogous advantages over the cultures of other phage groups.

Experimental osteomyelitis. IV. Therapeutic trials with rifampin alone and in combination with gentamicin, sisomicin, and cephalothin

Levels of rifampin, gentamicin, sisomicin, and cephalothin in normal and osteomyelitic rabbit bones were measured, and the efficacy of these drugs in the treatment of osteomyelitis was evaluated. Single drug regimens, including rifampin for 14 days and gentamicin, sisomicin, and cephalothin each for 28 days, were relatively ineffective (5%-33% sterile bone cultures). Rifampin, administered for 28 days, sterilized the bones of 55% of treated animals. The combination of gentamicin and rifampin, given for either 14 or 28 days, sterilized the bones of 67% of treated animals. The combinations of rifampin plus sisomicin and of rifampin plus cephalothin, given for 28 days, were significantly more effective than these agents alone, sterilizing 90%-95% of bones. The combination of rifampin, sisomicin, and cephalothin, given for only 14 days, sterilized the bones of all treated rabbits. Staphylococci isolated from the bones of therapeutic failures that had received rifampin alone or in combination with other antibiotics were highly resistant to rifampin (minimal inhibitory concentration, greater than 250 mug/ml), whereas the organisms recovered from animals not receiving rifampin remained sensitive. Results of in vitro studies of synergy and/or bactericidal activity of antibiotic combinations correlated with in vivo results in some, but not all, instances.

Handwashing practices for the prevention of nosocomial infections

Handwashing is generally considered the most important procedure in preventing nosocomial infections, because many types of these infections may be caused by organisms transmitted on the hands of personnel. Personnel should wash their hands before and after significant contact with any patient. The risk of personnel acquiring transient hand carriage of organisms is usually greatest after contact with excretions, secretions, or blood; patients at greatest risk are those undergoing surgery, those with catheters, and newborn infants. Although handwashing with an antiseptic agent between patient contacts is theoretically desirable, handwashing with soap, water, and mechanical friction are sufficient ro remove most transiently acquired organisms. Antiseptic agents may produce excessively dry skin if used frequently, and any regimen of handwashing that leads to dermatitis negates the purpose of handwashing. We favor antiseptics for handwashing before surgery and other high-risk invasive procedures and in the care of newborn infants but prefer soap and water for other handwashing.

[The combined effect of supraoptimal temperature and chemotherapeutic preparations on the metabolism of adenylic nucleotides by Staphylococcus aureus]

Comparative investigation of the effect of nitrofurans on the metabolism of adenylic nucleotides of Staphylococcus aureus at 36 degrees and 40 degrees C was made. It was shown that increasing of the cultivation temperature intensified the bacteristatic effect of nitrofurans. The use of nitrofurans at supraoptimal temperature intensified the activity of ATP-ase and considerably decreased the ATP, ADP and increased the AMP of Staphylococcus aureus.

Abnormal forms of bacteria produced by antibiotics

Subinhibitory concentrations of antibiotics can produce in vitro aberrant forms of bacteria that are similar to those observed in specimens and cultures from patients being treated with antibacterial agents. Eight species of bacteria were grown on membranes placed on agar containing subinhibitory concentrations of nine antibiotics. The resulting organisms were examined by Gram stain and electron microscopy. Gram stains showed filamentous and granular forms of enterobacteria with bipolar staining, giant staphylococci, and rodlike pneumococci. Electron micrographs showed changes in the number and distribution of ribosomes in enterobacteria and septum abnormalities in cocci. Such abnormal forms can occasionally simulate the appearance of quite different species, and they may indicate the presence of a subinhibitory antibiotic concentration at the site of infection as a result of prior antibacterial therapy.

Methicillin-resistant staphylococci 1965-75

Methicillin resistance in Staphylococcus aureus has been one of the major problems of gram positive infections in hospitals in the Zurich area. Up to 1971, about 20% of staphylococcal disease was caused by these peculiar organisms. Since 1972, however, a gradual decrease in the number of methicillin-resistant organisms has been observed, with an unprecedented low of 3% in 1975. The nearly 700 methicillin-resistant cultures that have isolated since 1965 exhibited, with rare exceptions, conventional group-II patterns of lysis in phage-typing and similar antibiotypes. It is suggested that all these isolates are derivatives of a strain which has long existed in the staphylococcal population. The reasons for the changes in the frequency of this strain as an agent causing staphylococcal disease are unclear. The use of penicillinase-resistant beta-lactam antibiotics in hospitals does not seem to play a major role in the distribution and spread or in the disappearance of this strain.

[Comparative study of the biological activity of tetracycline hydrochloride and morphocycline by using reverse turbidimetry]

The method of back turbidimetry was used for determination of the biological activity of the antibiotics, since high turbidity of the nutrient medium with Staph. aureus as the testculture prevented from direct measurements. Broth containing phosphate buffer, Staph. aureus and definite concentrations of the antibiotic was used as the reference solution. The experiments showed that the differences in the biological activities of tetracycline hydrochloride and morphocycline may be found with the method of back turbidimetry 6-8 hours after the microbe cultivation on media with the antibiotics.

Chemistry of cephalosporin antibiotics. 28. Preparation and biological activity of 3-(substituted)vinyl cephalosporins

3-(Substituted)vinylcephem nuclei have been prepared by the reaction of 3-formylcephem derivatives with stabilized phosphoranes. Appropriate synthetic steps allowed preparation of a series of 3-ethoxycarbonylvinyl- and 3-carboxyvinylcephem derivatives bearing a variety of 7-acylamino functions. The phenoxyacetyl and thiopheneacetyl derivatives of the 3-cyanovinylcephem nucleus were also prepared. Although general gram-positive activity was comparable to cephalothin in many cases, against penicillin G resistant Staphylococcus aureus, the new cephalosporins were of low effectiveness. The 3-(substituted)vinyl cephalosporins had good activity against a number of gram-negative organisms. In some cases, this activity was excellent. The N-acetyl analogs had surprisingly good activity relative to N-acetyl-7-ACA. The phenylmalonoyl side-chain derivatives were shown to have an unusual antibacterial spectrum expansion (relative to previously known cephalosporins) to include activity against Serratia marcescens and Pseudomonas aeruginosa.

Clinico-pharmacological examination of gentamycin in thoracic surgery

Authors describe the distribution and antibiogram of 185 microorganism strains cultured from thoracic surgical diseases. Gentamycin has been efficacious in the great majority of Gram negative pathoorganisms even in cases where other antibiotics were ineffective. In 14 cases they determined gentamycin concentration of serum and removed lung tissue between the 30th and 120th minutes after intramuscular application of 80 mg gentamycin. The serum level was 2.2 to 6.4 mcg/ml, 4.6 mcg/ml in average, the lung tissue level 0.4 to 3.0 mcg/g, 1.3 mcg/g on an average, the distribution quoteint 30 to 70%, 37% in average. 17 patients were locally treated by gentamycin because of thoracic surgical infections. In acute cases the results have been good, in chronic cases improvement has been achieved.

Drug resistance in Staphylococcus aureus. Induction of macrolide resistance by erythromycin, oleandomycin and their derivatives

Antibacterial and inducer activities concerning inducible macrolide resistance in Staphylococcus aureus were investigated using 32 erythromycin, oleandomycin and other macrolide antibiotic derivatives and analogues. The macrolides were classified into five groups from very high to none according to their inducer activity.

Comparison of two methods for assessing the removal of total organisms and pathogens from the skin

A standard hand-wash sampling technique was compared with a simple finger-streak sampling method in assessing the relative effectiveness of a number of alternative preparations used for disinfecting the surgeon's hands (alcoholic 0.5% chlorhexidine, alcoholic 0.1% tetrabrom-o-methyl phenol, a 4% chlorhexidine detergent solution, aqueous 0.5% chlorhexidine, 2% 'Irgasan' detergent solution and, as control, bar soap). There was a fairly good correlation between the results of assessment by the two methods after a single disinfection and after six disinfections, three on one day and three on the next. Significant differences were shown in 21 comparisons between treatments when the hand-wash sampling test was used, and 16 of these comparisons also showed a significant difference by the finger-streak test. Staphylococcus aureus was found in hand samplings from 5 out of 8 nurses in the Burns Unit of Birmingham Accident Hospital by the hand-wash sampling method and from 2 of the same 8 nurses by the finger-streak method; the numbers were small, and no Staph. aureus were isolated from the same hands after 1 min. wash in 70% ethyl alcohol. Similar sampling on 29 nurses in other wards showed Staph. aureus on 3 nurses (one in large numbers) by the hand-wash technique and on 1 nurse by the finger-streak test; in only 1 nurse whose hands showed Staph. aureus before disinfection was the organism found, by hand-wash sampling, after disinfection. Parallel sampling of nurses' hands after washing with soap and water and after disinfection with 95% ethanol showed larger numbers of Staph. aureus in a hospital for skin diseases than in a general hospital, and a lower incidence and somewhat lower density of Staph. aureus after ethanol treatment than after washing with soap and water; Gram-negative bacilli, on the other hand, were commoner on hands in the general than in the skin hospital, and present in much smaller numbers after disinfection with ethanol than after washing with soap and water. Antibiotic sensitivity tests showed the frequent recurrence on the hands of some nurses of multi-resistant Staph. aureus with resistance patterns similar to those found in infective lesions in some of the patients; different sensitivity patterns were usually found in staphylococci isolated from the nose. Even in wards where many patients were infected, carriage by nurses' hands of a particular strain of Staph. aureus did not seem to last for more than a few days.

Effect of glucocorticosteroids on the phagocytosis and intracellular killing by peritoneal macrophages

The effect of hydrocortisone on the phagocytosis and intracellular killing by mouse peritoneal macrophages in vitro was studied by a method making it possible to measure these processes separately. The results showed that in vivo treatment with 15 mg of hydrocortisone acetate did not significantly decrease the phagocytosis of several bacterial species such as Staphylococcus albus, Staphylococcus aureus, Escherichia coli, Salmonella typhimurium, and Pseudomonas aeruginosa. The killing indexes of normal macrophages for the various microorganisms were found to be significantly different. This may indicate that the bactericidal mechanisms are not uniform for these bacteria. The effect of hydrocortisone on the intracellular killing was also variable. For Staphylococcus albus a normal killing index was found. For the other species of bacterial and for Candida albicans some decrease was found, but this was only significant for Salmonella typhimurium. It is concluded that a decrease host resistance due to glucocorticosterioid treatment is not caused by a direct effect of these drugs on the phagocytosis and intracellular killing by mononuclear phagocytes.

A study of the action of the cationic proteins from rabbit polymorphonuclear leucocytes on the staphylococcal cell membrane

The inhibitory effect of cationic proteins from rabbit polymorphonuclear leucocytes on the oxidation of NADH by staphylococcal membrane preparations is described. Both cyanide and haematin are shown to interfere with the inhibitory process, by different mechanisms. Other authors have shown that glucose repressed staphylococci are diverted to a fermentative mode of metabolism. These findings were confirmed by demonstrating that membrane preparations from staphylococci grown in the presence of glucose have diminished cytochrome and succinic dehydrogenase levels. From a comparison of the effect of the cationic proteins on NADH oxidation in membrane preparations from organisms grown normally and under conditions of glucose repression, and from knowledge of the different susceptibility to the cationic proteins of the two types of organisms, it is suggested that the cationic proteins exert their bactericidal action on staphylococci following an energy dependent binding to the membrane.

Effects of an antibacterial soap on the ecology of aerobic bacterial flora of human skin

The effects of ad lib use of an antibacterial soap containing 1.0% trichlorocarbanilide and 0.5% trifluoromethyldichlorocarbanilide on the bacterial flora of six skin sites of 132 subjects were measured by comparison with the flora of 93 control subjects who avoided the use of topical antibacterials. Each subject was examined once. The test soap produced significant reductions in geometric mean counts of the total aerobic flora on the back, chest, forearm, calf, and foot; counts were also reduced in the axilla, but not to a significant extent. The overall reduction by the test soap on all sites was 62% (P less than 0.001). Neither age nor sex influenced the effect of the soap on the flora. The antibacterial soap also reduced the prevalence of Staphylococcus aureus on the skin, mostly by virtually eliminating it from areas other than the axilla. Partial inhibition of the gram-positive flora was not accompanied by an increase in gram-negative species. The latter were found principally in the axilla; Klebsiella pneumoniae and Enterobacter aerogenes were the species most frequently found.

Microbial kinetics of drug action against gram-positive and gram-negative organisms. II: Effect of clindamycin on Staphylococcus aureus and Escherichia coli

Clindamycin-affected Staphylococcus aureus cultures show biphasic steady-state generation curves. An initial (phase I) generation of the clindamycin-affected Staph. aureus is followed by an ultimate (phase II) generation at the same dose level. The phase I apparent generation rate constant is greater than the phase II apparent generation rate constant and suggests the development of resistant Staph. aureus mutants to clindamycin action after a finite period of drug-bacteria contact at any subcompletely inhibitory concentration level. It is rationalized that the increased resistance to drug action in mutant strains is due to a comparatively reduced ribosomal binding affinity for clindamycin. In contrast, clindamycin-affected Escherichia coli cultures show monophasic steady-state generation curves at all concentration levels; E. coli cultures do not develop resistance to clindamycin action. The dependence of the apparent generation rate constant on drug concentration yields a sigmoidal curve, which is coincident by a potency factor for the phase I and phase II generations of clindamycin-affected Staph. aureus and suggests a common mechanism of action for both generation phases. That of clindamycin-affected E. coli yields an asymptote curve, which indicates a different mechanism of action. Clindamycin possesses both a bacteriostatic and a bactericidal action on initial and mutant resistant strains of Staph. aureus, whereas its action on E. coli is only bacteriostatic. Consequently, clindamycin has a minimum inhibitory concentration (MIC) against E. coli that is about 1000 times the MIC value against Staph. aureus at 37.5 degrees. The effect of pH changes in broth media on generation inhibition of both Staph. aureus and E. coli by clindamycin action indicates that the unprotonated fraction of drug concentration contributes to the activity, possibly because of its ready penetration through cell membranes.

[Microbiological study of gentamiycin]

Gentamycin prepared at the All-Union Research Institute of Antibiotics did not differ by its antibacterial spectrum and the activity level from gentamycin samples from other countries. By its activity against clinical strains of Ps. aeruginosa gentamycin was somewhat inferior than polymyxin but much more superior than carbenicillin. An agar-diffusion method using Bac. pumilus NTCC 8241 as the test microbe was developed for determination of gentamycin activity. The gentamycin sulfate complex and the components of gentamycin had the same activity levels, antibacterial spectrum and diffusion capacity.

Microbial kinetics of drug action against gram-positive and gram-negative organisms. III: Effect of lincomycin and clindamycin combinations on Staphylococcus aureus and Escherichia coli

The functional dependencies of apparent first-order generation rate constants kapp, of drug-affected cultures on drug concentrations indicate that lincomycin and clindamycin possess the same mechanism of action, which is bacteriostatic, against Staphylococcus aureus. Clindamycin also possesses another mechanism of action, which is bactericidal, at high concentration levels. However, clindamycin possesses only one of the two mechanisms of lincomycin action, which is bacteriostatic, against Escherichia coli. The relative potency of action of a clindamycin-lincomycin combination against Staph. aureus is variable, and the effective ratio ranges between 5:1 and 9:1; the effective ratio against E. coli is fixed at 6:1 over a wide concentration range. This difference is attributed to differences in bioavailability and/or binding characteristics of the drugs for bioreceptors, as a consequence of structural modifications in the drug molecules, and to differences in modes of action in the respective organisms. Mixtures containing equipotent fractions of clindamycin and lincomycin show "equivalence" or "indifference" of effects on Staph. aureus. The combined action of the mixtures can be quantitatively predicted from the separate dose-response curves of either component drug alone. Therefore, it is concluded that clindamycin and lincomycin may bind to the same receptor site that is engaged in microbial protein synthesis to inhibit the generation of Staph. aureus. However, combinations of clindamycin and lincomycin are less active than the a priori equipotent concentration of either drug alone in their action against E. coli, demonstrating unequivocally an antagonism of effects. Furthermore, the degree of antagonism is dependent on the order of addition of the drugs, which is attributed to the possibility that clindamycin and lincomycin bind differently on active and allosteric loci of the same receptor site functionally engaged in protein synthesis in E. coli. A rational approach to the quantification and prediction of combined antibiotic action must, therefore, be based not only on the kinetics and mechanisms of action as well as on the dose-response relationship over a wide concentration range for the separate antibiotics but also on the strain and species of the test organism.

Comparative sensitivity of penicillinase producing Staphylococcus aureus to four cephalosporin antibiotics

One hundred and seven strains of penicillinase producing Staphylococcus aureus were tested for their sensitivity to four cephalosporin antibiotics--cephalothin, cephaloridine, cephradine and cephalexin. All the strains were sensitive to these antibiotics. Cephaloridine was the most effective antibiotic and cephradine the least effective as measured by their minimum inhibitory concentration. Varying the inoculum size had no significant effect on the MIC of cephradine.

[Effect of trypsin on the activity of tetracycline, erythromycin and levomycetin]

Trypsin had an antimicrobial effect on Staph. aureus. Increasing of protein in the broth culture of the staphylococci was inhibited in the presence of 50 gamma/ml of trypsin by 42.8%. The activity of tetracycline, erythromycin and levomycetin increased, when they were used in combination with trypsin, the effect of the trypsin combinations with tetracycline or levomycetin was additive, while that of the combination with erythromycin was synergistic.

Silver nitrate ophthalmic solution and chemical conjunctivities

The current status of nursery routines of prophylaxis against ophthalmia neonatorum were surveyed by mail questionnaire to 100 leading maternity hospitals. More than 20% of the respondents were not using silver nitrate, mainly because of chemical conjunctivitis. The clinical significance and incidence of chemical conjunctivitis were studied in 1,000 newborns whose eyes were handled differently. Rinsing after instillation of silver nitrate does not reduce the conjunctival irritation. Although 90% of the infants had conjunctivitis in the first hours of life, the majority cleared within 24 hours. Chemical conjunctivitis did not increase secondary infection, neither did it mask bacterial infection. Silver nitrate is effective in vitro against Neisseria gonorrhoeae and Staphylococcus aureus in a concentration of 0.1% and against Escherichia coli in a concentration of 0.01%.

[Antibacterial activity of a carbenicillin-cephaloridin combination]

The effectiveness of the combination of carbenicilline and cephaloridine in the ratio of 4:1 was studied. The antibacterial activity of the association whether in vitro or in vivo is sinergic, that is, superior to the simply addition by the individual components. The hematic levels of the combination remain high up to 5 hours after the administration and are greater than those obtained with carbenicilline alone. Levels in the urine are high, therefore the species judged to be resistent in vitro may become sensitive.

Nation-wide survey of antibiotic resistance by means of a computer: bacterial strains from the urine, stool, and upper respiratory tract

All-nation data of antibiotic resistance of about 200 000 bacterial strains isolated in the Slovak Socialist Republic in 1973 have been grouped, and compared, by means of a computer, into resistances of strains isolated from the urine, from upper respiratory tract (URT), from stool and from other pathological materials. In general, urine strains of all species investigated were found to be more resistant to "main antibiotics", and, suprisingly, to septrin, than strains from other sources. Strains of Staphylococcus aureus, and, notably, of Klebsiella-Enterobacter from the URT are generally more susceptible to antibiotics than strains of these species isolated from other sources. Urine strains of E. coli, P. mirabilis and Ps. aeruginosa show a high degree of resistance almost to all antibiotics, with exception of gentamicin and colistin (for E. coli and Ps. aeruginosa only). Further antibiotics for combatting these strains are urgently needed. Similar computer-assisted monitoring of strains from the very specified sources may be easily adapted for individual hospitals, clinics and even wards.

Transformation reveals a chromosomal locus of the gene(s) for methicillin resistance in Staphylococcus aureus

The localization of the gene(s) mediating methicillin (mecr) in Staphylococcus aureus was determined by transformation with deoxyribonucleic acid (DNA) from a natural mecr strain (DU 4916) and transformation obtained with DNA from this strain. Streptomycin resistance genes (strr) and novobiocin resistance genes (novr) were used concurrently as representatives for chromosomal genes; penicillinase (PI254) and tetracycline plasmids were used as examples of medium- and small-size extrachromosomal genes, respectively. Superinfection of the lysogenic recipients with the competence-inducing phage phi11 or 83A enhanced transformation for all markers. Phenotypic expression of cadmium (cadr), tetracycline (tetr), or methicillin resistance (mecr) did not appear to require a host recombination system since a recA1 mutant could serve as the recipient provided it was superinfected with a competence-inducing phage. There was, furthermore, no requirement for preexisting plasmids for phenotypic expression. Ultraviolet irradiation of transforming DNA enhanced at low doses the transformation frequency for chromosomal genes strr and novr but not for mecr, cadr, or tetr. The gene(s) for mecr was transformed with chromosomal DNA after sodium dodecyl sulfate-sodium chloride extraction and after neutral sucrose gradient centrifugation of bulk DNA from wild-type strain DU 4916 and the transformats. No cavalently closed circular DNA or open circular DNA carrying the methicillin resistance gene(s) could be detected in the wild type or the transformants either by ethidium bromide-cesium chloride gradient centrifugation or by zonal rate centrifugation of cells directly lysed on top of the gradients. The mecr gene(s) is thus probably of chromosomal nature but possibly under recombinational control of phage genes, since transfer of mecr is independent of the recA1 gene(s) but can be accomplished in this strain after superinfection with a competence-inducing phage. Ultraviolet light inactivation of transforming DNA shows first-order kinetics for mecr transformability similar to that observed for both transfecting and plasmid DNA.