In vitro activity of sparfloxacin, ciprofloxacin, ofloxacin, and other antibiotics against bloodstream isolates of gram-positive cocci

The in vitro activity of sparfloxacin was compared with the activities of ciprofloxacin, ofloxacin, and six other antimicrobial agents against 323 bloodstream isolates of staphylococci (both oxacillin susceptible and resistant) enterococci, and pneumococci. Sparfloxacin was more active than both ciprofloxacin and ofloxacin against all the isolates tested. Its activity (MIC for 90% of strains tested < or = 0.10 microgram/ml) against oxacillin-susceptible staphylococci was superior to that of ciprofloxacin and ofloxacin by at least fourfold. Sparfloxacin was also more potent against pneumococci. However, fluoroquinolone resistance was noted among oxacillin-resistant strains of Staphylococcus aureus and coagulase-negative staphylococci.

In vitro activities of ramoplanin, selected glycopeptides, fluoroquinolones, and other antibiotics against clinical bloodstream isolates of gram-positive cocci

The susceptibilities of 316 gram-positive bacteremic isolates to ramoplanin, vancomycin, and teicoplanin and seven other antibiotics were tested. Ramoplanin demonstrated MICs of < or = 0.25 microgram/ml for at least 99% of Staphylococcus aureus isolates and 100% of coagulase-negative staphylococci tested. For both oxacillin-susceptible and oxacillin-resistant S. aureus and coagulase-negative staphylococci, the activity of ramoplanin surpassed those of both vancomycin and teicoplanin. Ramoplanin and teicoplanin had comparable activities against enterococci and Streptococcus pneumoniae and were superior to vancomycin.

The in-vitro activity of temafloxacin, against gram-positive bacteria

Temafloxacin, a new fluoroquinolone with enhanced activity against Gram-positive bacteria, was compared with other antibiotics. A review of the literature on the in-vitro activity of temafloxacin was also done. The susceptibility of Gram-positive cocci isolated from blood cultures was determined using a broth microdilution method. Temafloxacin MIC90s for Staphylococcus aureus (oxacillin-sensitive and -resistant) and Streptococcus pneumoniae were less than 0.12, less than 0.12 and 0.76 mg/L respectively. Temafloxacin was more active than either ciprofloxacin or ofloxacin against these organisms. A review of the literature supported these findings. Temafloxacin was the most active of the quinolones tested against a small number of S. pneumoniae with decreased sensitivity to penicillin. Temafloxacin activity was not appreciably affected by changes in pH or the presence of serum, but activity was slightly reduced in urine at pH 6.5-7.2, and at high magnesium ion concentrations. With the exception of S. pneumoniae at high concentration, no significant inoculum effect was observed.

Comparative in vitro activities of teicoplanin, vancomycin, oxacillin, and other antimicrobial agents against bacteremic isolates of gram-positive cocci

The in vitro activities of teicoplanin and vancomycin were compared with those of six other antimicrobial agents against 460 bacteremic isolates of gram-positive cocci. Teicoplanin was as active as vancomycin but less active than ciprofloxacin against staphylococci. Teicoplanin was the most potent of all agents tested against enterococci and had excellent activity against pneumococci.

Comparative antimycobacterial activities of difloxacin, temafloxacin, enoxacin, pefloxacin, reference fluoroquinolones, and a new macrolide, clarithromycin

The activities of fluoroquinolones and a new macrolide against 30 clinical isolates of Mycobacterium tuberculosis were determined in vitro by agar diffusion. In order of relative potencies against M. tuberculosis, temafloxacin (MIC for 90% of isolates [MIC90], 2.3 micrograms/ml) was at least as active as the reference quinolones ofloxacin (MIC90, 2.4 micrograms/ml) and ciprofloxacin (MIC90, 4.3 micrograms/ml). Less active were difloxacin (MIC90, 4.7 micrograms/ml), pefloxacin (MIC90, 6.7 micrograms/ml), and enoxacin (MIC90, 8.3 micrograms/ml). The macrolide clarithromycin was more potent than erythromycin but less potent than the fluoroquinolones. Our results suggest that the newer fluoroquinolones and clarithromycin should be included with ciprofloxacin and ofloxacin in pharmacokinetic studies that may lead to trials in human subjects with mycobacterial infections.

Detection of antigens from gram-negative bacilli in urine of children with urinary tract infections. I. Common antigen of Enterobacteriaceae

Enterobacterial common antigen (ECA) has attracted considerable interest since the original publication by Kunin in 1962. In the present study we demonstrated this antigen directly in the urine from patients with urinary tract infections (UTI) elicited by enterobacteria. Sheep erythrocytes were incubated with UTI urine; this resulted in their coating with ECA, which was studied by means of hemagglutination by anti-ECA serum. Test tube hemagglutination and the more simple slide hemagglutination were employed and with both procedures similar results were obtained. Positive results were observed in 94-99% of urine specimens from enterobacterial UTI collected in The Buffalo Children's Hospital in the 1960s. ECA in urine could also be demonstrated by hemagglutination inhibition. In this test, antibodies in anti-ECA serum were neutralized as a result of incubation of this serum with urine, and agglutination by the antiserum of sheep erythrocytes coated with a standard ECA preparation was prevented or reduced. By means of this latter test, ECA could be demonstrated in 67-88% of urine specimens from enterobacterial UTI. The possible diagnostic application of these tests has been discussed.

Detection of antigens from gram-negative bacilli in urine of children with urinary tract infections. II. Thermostable bacterial proteins

An enzyme immunoassay for detection of bacterial antigens in urine specimens from urinary tract infections (UTI) was developed. The antigens detected in infections by Enterobacteriaceae: Escherichia coli, Enterobacter aerogenes, and Proteus sp. were different from the enterobacterial common antigen (ECA). They were digested by trypsin and were characterized by remarkable thermostability; their molecular weights were approximately 34,000 and 31,000. They were detected by means of antisera to ECA or to suspension of E. coli. The frequency of positive results with urine specimens from enterobacterial UTI was 87-99%. In contrast, the urine specimens of UTI by Pseudomonas aeruginosa were positive in fewer than 20% with anti-E. coli sera, but were positive in more than 85% in tests with antiserum to P. aeruginosa. The possible diagnostic application of the described tests was discussed.

Relationship to coagglutination of immunoglobulin class dissociated from Escherichia coli-antibody complexes

Immunoglobulin G was present only in those Escherichia coli antisera causing coagglutination, as determined by immunoelectrophoretic patterns in eluates of antigen-antibody complexes.

Coagglutination as an expedient for grouping Escherichia coli associated with urinary tract infections

Thirteen serogroups of Escherichia coli most frequently are responsible for urinary tract infections in humans. Knowledge of serogroup is required for epidemiological reasons and to help differentiate between new and reemergent strains in infected patients. Coagglutination and bacterial agglutination were compared as serodiagnostic tools for identifying groups of E. coli associated with these infections. In contradistinction to bacterial agglutination, coagglutination showed no cross-reactions for 12 of the 13 known strains obtained from the Center for Disease Control. A single antiserum, E. coli O4, caused bacterial agglutination and not coagglutination. In addition, staphylococcal cells that were coated with antiserum reacted with sheep erythrocytes that had been treated with soluble extract of E. coli. The latter reaction, cohemagglutination, was as specific and rapid as coagglutination; easily visible patterns of clumping developed within 1 min after sensitized staphylococci and E. coli reagent were mixed. These results revealed a method that is sensitive and reproducible for identifying serogroups of E. coli responsible for urinary tract infections.

Immunogenic cross-reactivity between human tissues and the enterobacterial common antigen

Sterile tissues of human subjects free from infection and malignancy were assessed for an antigen that cross-reacts with the enterobacterial common antigen (ECA). Extracts of heated homogenates (HE) and ethanol-soluble (ES) fractions of liver, kidney, muscle, and heart tissues were examined for their capacities to react with ECA antibodies, as measured by hemagglutination procedures, and to elicit ECA humoral antibodies in rabbits. Both HE and ES extracts of human liver and kidney tissues specifically inhibited ECA hemagglutination. However, ES fractions of HE preparations demonstrated significantly greater inhibiton than their HE sources. In addition, both liver and kidney ES fractions primed rabbits for a rapid and specific secondary ECA humoral response to a single administration of ECA. The cross-reactivity noted between human tissue and ECA cannot be attributed to indigenous microorganisms present in the tissues, as subcultures of tissue homogenates were always sterile. Moreover, preliminary experiments with human fetal subjects, devoid of microbial flora, yielded similar results.

Effect of erythrocytes treated with enterobacterial common antigen on experimental Salmonella typhimurium infection of mice

The immunogenicity of enterobacterial common antigen (CA)-treated horse or mouse erythrocytes was determined in Swiss white albino mice by comparing survival rates with control mice, immunized with P. aeruginosa fraction-treated RBC and challenged in parallel with 10 LD50 S. typhimurium. The administration of small amounts of CA on horse, but not mouse, RBC significantly delayed mortality; protection was only marginally less than that evoked with 12-fold larger amounts of CA in the absence of RBC. Survival in infected animals was transient; independent of immunogen or control preparation employed, all mice were dead by day 15 after challenge.

Cross-reactivity between organ extracts of gnotobiotic mice and enterobacterial common antigen

Organs of gnotobiotic mice were assessed for an Ag (CRA) which cross-reacts with common enterobacterial Ag(CA). To this end, extracts of homogenates of spleens, livers, paired kidneys and colons were examined for their capacities to engender humoral and cellular events in rabbits. The immjnogenicity of CRA in the rabbit cannot be predicted on the basis of CA hemagglutinin-inhibition studies alone. According to this parameter, CRA was present in mouse spleens, livers and paired kidneys but absent in colons. However, the identical preparations, including colons, primed rabbits to engender specific CA hemaglutinins after a single administration of enterobacterial CA. Also, spleens of these same rabbits were colonized with rosette-forming cells against sheep red blood cells treated with various enterobacterial sources of CA. These findings may account, in part, for the apparent refractiveness or equivocal response mice have to administered CA and infectious challenge.

Immunologic mimicry between mouse tissue and enterobacterial common antigen

Organs of Swiss white albino and C57BL/6Ha mice were assessed for an antigen (CRA) which cross-reacts with common enterobacterial antigen (CA). To this end, supernatant fluids (HKS) and ethanol-soluble fractions (ES) of heated homogenates of spleens, kidneys, and livers were examined for their capacities to react with CA hemagglutinins and to engender humoral and cellular events in the rabbit. The immunogenicity of CRA in the rabbit can not be predicted on the basis of CA hemagglutinin neutralization studies alone; although CRA was identified in the liver extracts of both mouse strains, according to this parameter, only the liver fraction of Swiss white albino mice elicited significant numbers of rosette-forming cells (RFC) in the spleens of rabbits. Also, kidney fractions, which primed the rabbits for booster with CA, were less effective in stimulating RFC in the spleens failed to inhibit CA hemagglutination and did not prime rabbits for a CA hemagglutinin response, these same preparations clearly evoked RFC in rabbit spleens. Thus, the antigenicity and immunogenicity of CRA in target organs of mice reflect the mouse strain, extraction procedure, and testing method employed.

Hemagglutinin response of human subjects to common enterobacterial antigen

Ten human volunteers were immunized intravenously with ethanol-soluble common enterobacterial antigen (CA) obtained from Escherichia coli O111. The immunogen contained 6 mg/ml, excluding salts. The antigen was given in amounts of 2 ml each in dilutions of 1:250 (48 mug) and 1:125 (96 mug), respectively, 1 week apart. Serum specimens were obtained prior to immunization and 1 week after the last injection. The CA hemagglutinins were titrated by means of the passive hemagglutination test, with CA from E. coli O14 as indicator antigen. The injections were well tolerated without side-effects by all subjects. A significant (> fourfold) increase in the titers of CA hemagglutinins was observed following immunization in 9 out of 10 volunteers. These results indicate the feasibility of immunization with CA of human subjects and suggest exploration of immunization against infection caused by Enterobacteriaceae producing this common enterobacterial antigen.

Hemagglutination by Mixtures of Human γ-Globulin and Heterogenetic Bacterial Antigen

Study on hemagglutination by mixtures of heterogenetic bacterial antigen and corresponding antibodies revealed the following results: Mixtures of antigen and γ-globulin cause agglutination of human erythrocytes that have been treated with either pancreatic protease, trypsin, ficin, bromelin, or papain.Crude extracts of Staphylococcus aureus, Bacillus subtilis, Bacillus cereus, and Listeria monocytogenes are all effective.Serum Fractions II 1, 2 and II 3 are both effective.Serum containing this antibody in comparable titer does not cause hemagglutination in the presence of antigen.Absorption of heterogenetic antibody from γ-globulin considerably reduces the hemagglutinating capacity of γ-globulin in the presence of antigen.This hemagglutination reaction is inhibited by human and animal serum; the serum factor(s) is heat stable at 75°C and only slightly affected at 100°C. Ultrafiltrates of serum are ineffective. Egg yolk, but not egg white, in high dilutions inhibits the reaction. Mixtures of cardiolipin and lecithin or cholesterol are also effective as inhibitors.

The Effects of Antibiotics on Enterobacterial Lipopolysaccharides (Endotoxins), Hemagglutination and Hemolysis

A study on the effects of various antibiotics on enterobacterial lipopolysaccharides and hemagglutination and hemolysis revealed the following results: Small amounts of polymyxin B (1–1.25 μg/ml) and neomycin (12.5–15 μg/ml) and larger amounts of humycin (50–100 μg/ml) and streptomycin (40–125 μg/ml) inhibit enterobacterial hemagglutination and hemolysis if the antibiotics are added to highly purified lipopolysaccharide (5 μg/ml) prior to modification of sheep red blood cells. Somewhat larger amounts are required for inhibition with less highly purified lipopolysaccharides and crude preparations.Bacitracin (2500 μg/ml), penicillin (1000 μg/ml), erythromycin (1000 μg/ml), and novobiocin (500 μg/ml) have no such effect.Polymyxin B, neomycin, humycin, and streptomycin do not inhibit hemagglutination and hemolysis of previously modified red blood cells.Treatment of red blood cells with the antibiotics prior to modification does not prevent hemagglutination and hemolysis by homologous bacterial antibody and complement.Treatment of human red blood cells of blood group A with mixtures of antibiotics (polymyxin B or neomycin), S. sonnei lipopolysaccharide, and S. sonnei antibodies of human origin does not inhibit hemagglutination by blood group A antiserum, indicating that the red blood cells had not become inagglutinable. Coombs antiserum does not cause hemagglutination of these treated red blood cells.Polymyxin B, neomycin, humycin, and streptomycin do not abolish antibody neutralizing capacity of enterobacterial lipopolysaccharides in hemolysis inhibition tests, although a slight degree of inhibition was found.It is tentatively concluded that polymyxin B, neomycin, humycin, and streptomycin interfere with the attachment of lipopolysaccharides to the surface of red blood cells and, to a lesser degree, cause alteration of their antibody reacting capacity.The significance of the results is discussed with particular reference to the possible specificity of the action of antibiotics on enterobacterial lipopolysaccharides and the bearing of the findings on the mode of action of the antibiotics.

Studies of Enterobacterial Lipopolysaccharides

The effects of physical and chemical agents on the biological properties of purified enterobacterial lipopolysaccharides have been studied. The following observations have been made: The untreated lipopolysaccharides are markedly effective as antibody neutralizing antigens. They possess a high degree of toxicity and pyrogenicity, but they have only a limited erythrocyte-modifying capacity.Treatment of these lipopolysaccharides with heat or with sodium hydroxide for short periods of time results in an increase of their capacity to modify erythrocytes without alteration of their antigenicity (antibody-neutralizing potency) toxicity or pyrogenicity. Treatment with sodium hydroxide for longer intervals does not affect their antibody-neutralizing and erythrocyte-modifying capacity, but results in a marked loss of toxicity and pyrogenicity.Oxidation of the Escherichia coli lipopolysaccharide with periodate yields a compound of low toxicity and marked pyrogenicity. The capacity of this substance to neutralize antibody is almost completely abolished.A degraded, lipid-free polysaccharide component obtained from Salmonella abortus equi lipopolysaccharide exhibited reduced antibodycombining capacity when compared with the original product; treatment with heat and sodium hydroxide fails to produce any erythrocyte-modifying capacity.Red blood cells which have been modified with heated or sodium hydroxide treated lipopolysaccharides specifically absorb homologous bacterial antibodies. Erythrocytes which have been in contact with equivalent amounts of untreated antigens do not.The results of this study indicate that the various biological activities of bacterial lipopolysaccharides are affected differentially by different physical and chemical agents.The significance of the data has been discussed with particular reference to the relationship of chemical and physical-chemical characteristics of enterobacterial lipopolysaccharides and their components to the various biological activities of these compounds.