Numerical taxonomy ofKlebsiella pneumoniae strains isolated from clinical and nonclinical sources

A total of 180 clinical and nonclinical isolates ofKlebsiella pneumoniae, for which 99 characteristics were recorded, were subjected to numerical taxonomy analysis. Of these strains, 172 clustered into five major groups, with an overall similarity of 64%. Intragroup similarities ranged from 77 to 82%, with the subgroups corresponding to the speciesK. pneumoniae sensu stricto, K. oxytoca, andKlebsiella spp. 1, 2, and 3. Biochemical tests useful in distinguishing the species included production of indole, degradation of pectate, growth at 10°C, fecal coliform response, production of urease, fermentation of inulin andd-tartrate, utilization ofl-arginine and gentisate andm-hydroxybenzoate, and pigment formation ond-gluconate ferric citrate agar.     

Antimicrobial activity of some salts of dialkylthiophosphoric acids

A total of 18 derivatives of O,O-dialkylthio- and O,O-dialkyldithiophosphoric acids were tested for antimicrobial activity using strains ofStaphylococcus aureus, Bacillus subtilis, Escherichia coli andCandida albicans. The activity was found to depend on the length of the alkyl substituent and/or the cation size. All derivatives were ineffective withE. coli andC. albicans.     

Influence of lipopolysaccharide on external hemolytic activity ofSalmonella typhimurium andKlebsiella pneumoniae

Excretion ofEscherichia coli -hemolysin was tested in rough and smooth strains ofKlebsiella pneumoniae andSalmonella typhimurium. Smooth strains harboring the hemolytic recombinant plasmid pANN202-312 showed a five- to tenfold increase in the hemolytic activity evaluated in the external medium compared with isogenic rough strains harboring the same plasmid.     

Serological cross-reactivity betweenKlebsiella pneumoniae K47 andSporothrix species

The serological cross-reactivity ofKlebsiella pneumoniae K47 antiserum with antigens of 11Sporothrix species was investigated by use of immunodiffusion. Cross-reactions occurred withK. pneumoniae K47 and theSporothrix speciesS. schenckii, S. schenckii var.luriei, S. curviconia, andS. inflata.     

Establishment of the phylogenetic relationships between the microbial producers of cyclodextrin glucanotransferases using complete amino acid sequences

A phylogenetic tree was constructed on the basis of the amino acid sequences of the known cyclodextrin glucanotransferases (CDGTs), including those deduced from the nucleotide sequences ofBacillus sp. strain 6.6.3 andPaenibacillus macerans IB-7 genes encoding α- and β-CDGTs. The tree clearly demonstrates the existence of distinct phylogenetic groups of CDGT-producing microorganisms and the divergence of the α-, β-, and γ-CDGT produced by microorganisms from the generaBacillus, Paenibacillus, Brevibacillus, andThermoanaerobacter from a common ancestor, whereas the CDGT ofKlebsiella pneumoniae is independent and results from the convergence of different ancestors. The degree of homology of the leader peptide sequences of CDGTs may serve as a criterion of intraspecies relatedness between CDGT-producing microorganisms.     

Distribution and in situ survival and activity ofKlebsiella pneumoniae andEscherichia coli in a tropical rain forest watershed

For a period of 7 months water samples were analyzed for the presence ofKlebsiella pneumoniae and fecal coliforms at 11 sites in a cloud rain forest watershed in Puerto Rico. Diffusion chamber studies were conducted at two sites which were found to contain low numbers of naturally occurringK. pneumoniae and fecal coliforms. These studies indicated that bothK. pneumoniae andEscherichia coli may be capable of surviving environmental conditions for extended periods of time. The presence of both bacteria in pristine natural waters is indicative of their being autochtonous to tropical environments. Thus, as a result, the use of coliform and even fecal coliform bacteria as indicators of fecal pollution may be misleading when applied to countries with a tropical climate.     

Synthesis of shorter active analogues of Bactenecin7: The effect of change of N-terminal configuration on antimicrobial activity

Summary Bactenecin7, a cationic antibacterial peptide, contains a repeating region of Xaa-Pro-Arg-Pro (Xaa=hydrophobic residues). A series of peptides, Xaa-Pro-Arg-Pro (Xaa=D-Ala, D-Leu, D-Val, D-Phe and D-Lys) were synthesized to investigate the effect of change ofN-terminal configuration on antimicrobial activity. The conformational preferences of these peptides in water and TFE were examined by circular dichroism. All the synthetic peptides with D-amino acid substitution atN-terminal showed potent antifungal activity againstAspergillus niger, Aspergillus flavus andFusarium moniliforme at the concentration level of 8–10 μg ml⁻¹. But the same tetrapeptides were unable to kill or suppress the growth of gram-negative and gram-positive bacteria such asEscherichia coli HB101,Pseudomonas aeruginosa, Klebsiella pneumoniae andStaphylococcus aureus even at the concentration level of 400 μg ml⁻¹. The present study reveals that the change of configuration at theN-terminal of tetrapeptide has negative impact on antibacterial activity but enhanced antifungal activity.     

Metabolism of tannin-protein complex by facultatively anaerobic bacteria isolated from koala feces

The metabolic pathways involved in degradation of tannin-protein complex (T-PC) were investigated in various facultatively anaerobic bacteria, with specific reference to fecal isolates from the koala including T-PC-degrading enterobacteria (T-PCDE),Streptococcus bovis, Klebsiella pneumoniae, andK. oxytoca. It was demonstrated that T-PCDE andS. bovis biotype I were capable of degrading protein complexed with gallotannin (a hydrolyzable tannin), but not that complexed with quebracho (a condensed tannin). Subsequent studies showed that these strains metabolized gallic acid to pyrogallol. Strains ofKlebsiella pneumoniae andK. oxytoca, which did not degrade T-PC, also metabolized gallic acid into pyrogallol. Pyrogallol was not degraded by any strains studied, but it was not detected in fresh feces of the koalas. The majority of strains isolated from feces could degrade phloroglucinol. Based on these findings, we propose that members of the gut microflora of the koala cooperate in the degradation of T-PC.     

Differences in the envelope proteins ofChlamydia pneumoniae,Chlamydia trachomatis,andChlamydia psittaci shown by two-dimensional gel electrophoresis

Analysis by two-dimensional gel electrophoresis of theN-laurylsarkosinate(Sarkosyl)-insoluble envelope complexes ofl-^[35]S-cysteine-iabeled elementary bodies ofChlamydia pneumoniae strain IOL-207,Chlamydia trachomatis serovar LGV2, D, and F, andChlamydia psittaci strain 6BC showed differences in the molecular charges of chlamydial outer membrane proteins. The apparent isoelectric point (pI) of the major outer membrane protein ofC. pneumoniae strain IOL-207 was 6.4, whereas the pI of the major outer membrane protein of theC. trachomatis andC. psittaci strains differed little from one another, ranging from 5.3 to 5.5. The 60-kDa cysteinerich protein ofC. pneumoniae was the only 60-kDa chlamydial protein with a pI value (5.9) more acidic than that of the corresponding major outer membrane protein. As a general rule, the charges of both the 60-kDa and the lowmolecular-mass (12–15 kDa) cysteine-rich proteins were widely variable, depending on the strain. However, in cach individual strain, the variation of the charge of the 60-kDa protein had a compensatory change in the lowmolecular-mass cysteine-rich protein.     

Screening ofBifidobacterium strains for bacteriocin production

Summary Thirteen strains of bifidobacteria (Bifidobacterium) were examined for bacteriocin production. One strain among these produced bacteriocin which is active against lactic streptococci strains and against other species ofBifidobacterium, Clostridium andLactobacillus, but not against Gram-negative bacteria such asPseudomonas, Klebsiella, Serratia andEscherichia coli.Bacteriocin activity was inhibited by proteolytic enzymes, but not by heating 15 min or30 min at 100°C, and it was resistant for 15 min at 121°C and active at pH between 2 to 10.     

Lytic effect ofVibrio cholerae elastase on Gram-positive and-negative bacteria

Elastase ofVibrio cholerae caused the lysis of freshly grown cells of Gram-negative (Pseudomonas aeruginosa, Proteus vulgaris, Salmonella paratyphi A andKlebsiella pneumoniae) bacteria. Gram-positive (Staphylococcus aureus andS. epidermidis) organisms were resistant to this enzyme. Heat killed and lyophilized Gram-positive and-negative bacteria (exceptS. aureus andS. epidermidis) showed higher sensitivity to elastase. Both Gram-negative and-positive bacteria were lyzed maximally by elastase at pH 8.0. At this pH, lytic activity of elastase was maximum in Tris-HCl and glycine-NaOH buffers followed by Tris-maleate and cacodylate buffers.     

Interaction of various bacteriocins withKlebsiella edwardsii var.edwardsii

The interaction of four different bacteriocins produced byKlebsiella pneumoniae andCitrobacter freundii strains with cells ofKlebsiella edwardsii var.edwardsii has been studied. All four bacteriocins have different activity spectra. The existence of multi-tolerant and multi-receptor-negative mutants supports the hypothesis that the specific receptor sites for these bacteriocins on sensitive bacteria have some components in common.Bacteriocins S6 and S8, produced byKlebsiella pneumoniae strains inhibit protein biosynthesis. Colicin A, produced byCitrobacter freundii inhibits all macromolecular synthesis, but pre-treatment of sensitive cells with colicin A had no influence on the production of ATP by oxidative phosphorylation in cell homogenates. Bacteriocin G196, also produced byCitrobacter freundii inhibits protein and RNA synthesis, with little effect on DNA synthesis. Homogenates of cells pre-treated with bacteriocin G196, show a substantial phosphorylating activity.The authors wish to thank Dr. W. de Vries for performing P:O measurements. The skilful technical assistance of Miss E. A. Spanjaerdt Speckman and Miss W. M. C. Kapteijn is gratefully acknowledged.The investigations were supported (in part) by the Netherlands Foundation for Chemical Research (SON) with financial aid from the Netherlands Organization for the Advancement of Pure Research (ZWO).     

Comparative in vitro activity of moxalactam (LY127935), other beta-lactam antibiotics,and aminoglycosides

Moxalactam (LY127935), a novel beta-lactam antibiotic, was compared with semisynthetic penicillins, cephalosporins, and aminoglycosides by the agar dilution method against 5,317 recent clinical isolates of facultative and anaerobic bactria. At 0.5 μg/ml, moxalactam inhibited 90% of all Gram-negative bacilli tested except forPseudomonas aeruginosa (81% inhibited by 32 μg/ml) andAcinetobacter calcoaceticus (88% inhibited by 32 μg/ml). More than 90% ofBacteroides fragilis andStaphylococcus aureus were inhibited by 4 μg/ml and 8 μg/ml, respectively. Moxalactam was at least 16-fold more active by weight than cephalothin, cefamandole, and cefoxitin forEscherichia coli, Klebsiella pneumoniae, andEnterobacter species, and 2- to 4-fold more active than cefoxitin forB. fragilis. Moxalactam was 4-fold less active than cefamandole and cephalothin forS. aureus and 2- to 4-fold less active than piperacillin forP. aeruginosa. Moxalactam was as active or more active than the aminoglycosides for all facultative Gram-negative bacilli except forP. aeruginosa. Moxalactam was inhibitory (minimal inhibitory concentration <16 μg/ml) for 20/27 gentamicin-resistant isolates and 8/13 amikacin-resistant organisms. Moxalactam’s in vitro activity against Gram-negative bacilli is markedly superior to presently available cephalosporins and, except forP. aeruginosa, is comparable to the aminoglycosides.     

Increased root exudation of14C-compounds by sorghum seedlings inoculated with nitrogen-fixing bacteria

Summary Organic components leaked fromSorghum bicolor seedlings (‘root exudates’) were examined by recovering¹⁴C labelled compounds from root solutions of seedlings inoculated withAzospirillum brasilense, Azotobacter vinelandii orKlebsiella pneumoniae nif-. Up to 3.5% of the total¹⁴C recovered from shoots, roots, and nutrient solutions was found in the root solutions. Inoculation with Azospirillum and Azotobacter increased the amounts of¹⁴C and decreased the amounts of carbohydrates in the root solutions. When sucrose was added as a carbon source for the bacteria, the increase of¹⁴C in the solutions did not occur. Quantities of¹⁴C found in the root solutions were proportional to amounts of mineral nitrogen supplied to the plants. Bacterial growth also was proportional to nitrogen levels. When sorghum plants were grown in soil and labelled with¹⁴CO₂, about 15% of the total¹⁴C recovered within 48 hours exposure was found in soil leachates.     

Expression of hemagglutination is dependent on environmental factors and bacterial concentration ofEscherichia coli andKlebsiella pneumoniae

Hemagglutination of human type A and guinea pig erythrocytes showed that both mannose-sensitive and mannose-resistant adhesive mechanisms (pili) were detectable in broth cultures ofEscherichia coli while only a mannose-sensitive mechanism (type 1 pili) was noted withKlebsiella pneumoniae. The degree of hemagglutination was shown to be related to differences in erythrocytes, bacterial concentration, and growth media constituents.Escherichia coli grown in human urine produced both types of hemagglutinins, whileK. pneumoniae cultured in urine continued to express only a mannose-sensitive hemagglutinin.     

Activity of an insoluble antimicrobial quaternary amine complex in plastics

Summary Growth and survival ofStaphylococcus aureus, Pseudomonas aeruginosa., Klebsiella pneumoniae andAspergillus niger were reduced by a low-solubility polysubstituted.-quaternary amine complex (Intersept^R) processed into the matrices of ethylene vinyl acetate, polystyrene and polyethylene., Recoveries of challenge microorganisms from agar film overlays and determination of the effects of the complex on radiolabelled-leucine transport by adhered cells and bacterial biofilms were more suitable for assessing inhibitory efficacies than standard agar diffusion or serial dilution procedures.     

Antagonistic interactions between fungal pathogens and phylloplane fungi of guava

Dominant phylloplane fungi of guava (Psidium guajava L.) were screened for their antagonistic activities against the two pathogens,Colletotrichum gloeosporioides andPestalotia psidii, bothin vitro andin vivo. Culture filtrates ofAspergillus niger, Fusarium oxysporum andPenicillium citrinum caused more than 50% growth inhibition ofC. gloeosporioides. Filtrates ofCephalosporium roseo-griseum andF. oxysporum were most effective in reducing the growth ofP. psidii. Volatiles produced from the cultures ofA. niger, F. oxysporum, P. citrinum andP. oxalicum inhibited the growth ofC. gloeosporioides, whereas volatiles fromC. roseo-griseum, F. oxysporum andTrichoderma harzianum inhibited the growth ofP. psidii. The inhibitory effect of volatiles decreased with increase in incubation time. In general, the maximum effect of volatiles was noticed after 48 h incubation. Different grades of colony interactions in dual cultures were recognised between the two pathogens and the phylloplane fungi examined. Maximum inhibition ofC. gloeosporioides was caused byAureobasidium pullulans, Cladosporium cladosporioides, epicoccum purpurascens, F. oxysporum andMyrothecium roridum, whereasAspergillus terreus, C. roseo-griseum andP. oxalicum significantly reduced the growth ofP. psidii. Application of a spore suspension of each test fungus inhibited lesion development of guava leaves caused by the test pathogensin vitro. Inhibition was more pronounced when the spore concentration was increased.A. pullulans, C. cladosporioides, E. purpurascens, F. oxysporum, andT. harzianum were found to be strongly antagonistic toC. gloeosporioides. A. niger, A. terreus, C. roseo-grisem andT. harzianum were strongly antagonistic toP. psidii.     

Effects of Brazilian green propolis extract on planktonic cells and biofilms of multidrug-resistant strains of Klebsiella pneumoniae and Pseudomonas aeruginosa

Abstract

Propolis could represent an alternative therapeutic agent for targeting multidrug-resistant bacteria due to its antimicrobial potential. The effect of Brazilian green propolis (BGP) aqueous extract (AqExt) was evaluated on eight multidrug-resistant clinical strains of Klebsiella pneumoniae and Pseudomonas aeruginosa, as well as on one reference strain for each bacterial species. The minimum bactericidal concentration (MBC) was determined and optimal concentrations were further evaluated in comparison with 0.12% chlorhexidine. The natural extract was chemically characterized by HPLC-DAD analysis. The MBC values ranged between 3.12 and 27.5?mg ml^?1. Analysis of bacterial metabolic activity after treatment for 5?min with BGP-AqExt revealed a strong antimicrobial potential, similar to chlorhexidine. The extract comprised several active compounds including quercetin, gallic acid, caffeic and p-coumaric acid, drupani, galangin, and artepillin C. Altogether, the findings suggest that BGP-AqExt is fast and effective against multidrug-resistant strains of K. pneumoniae and P. aeruginosa in planktonic cultures and biofilms.     

Inhibition of bacterial adherence to rat bladder epithelial cells by human immune serum globulin

The ability of commerical human immune serum globulin (HISG) to inhibit the adherence of urinary tract infection isolates to rat bladder epithelial cells was investigated utilizing an in vitro adherence system. Significant decreases in adherence were noted when strains ofEscherichia coli, Klebsiella pneumoniae, Proteus mirabilis, andEnterobacter cloacae were tested against five HISG preparations. An enzyme-linked immunosorbent assay indicated that all five HISG preparations also contained antibodies against type-1 pili isolated fromKlebsiella pneumoniae. The presence of antibodies directed against a bacterial adhesin and the effectiveness of HISG in inhibiting the attachment of a wide range of urinary pathogens to bladder cells suggest that HISG may have practical therapeutic values in the prophylaxis of diseases where bacterial adherence is a prerequisite for the initiation of infection.     

Cloning of pEA3, a large plasmid ofEnterobacter agglomerans containing nitrogenase structural genes

Summary A clone bank of an indigenous plasmid ofEnterobacter agglomerans containing structural nitrogen-fixation (nif) genes was established in a non-mobilisable, multicopy derivative of the cosmid vector pHC79. The restriction enzyme Bam HI was used to establish the clone bank and it was found that 96% of the clones contained inserts. The clones containingnif-genes were identified by Southern hybridisation usingKlebsiella pneumoniae nif DNA (KpnifHDKY) as the radioactive probe. Thenif-genes ofE. agglomerans showed extensive homology to those ofK. pneumoniae but the restriction enzyme fragment patterns of thenif-genes ofE. agglomerans were different. The plasmid bornenif-genes ofE. agglomerans are clustered as inK. pneumoniae.