A cationic antimicrobial peptide enhances the infectivity of Coxiella burnetii

The pulmonary arteriole remodeling in Wistar rats with respiratory infection induced by mycoplasma pneumoniae was observed using light microscopy and morphometry. The pulmonary artery pressure (PAP) and index of right ventricular hypertrophy (RVHI) were measured. The intimal and medial hypertrophy can be seen in the pulmonary arterioles, leading to vessel wall thickening and narrowing of the lumina. The total number of the pulmonary arterioles decreased (P < 0.01), and both pulmonary hypertension (Ppa 4.11 +/- 0.19 kPa) and right ventricular hypertrophy (RVHI = 34.96 +/- 3.91%) occurred. In addition, an interstitial pulmonary fibrosis (IPF) was found, in which the content of collagen in the lung tissue changed, i. e., type I collagen increased whereas type III one decreased, and the ratio of type I collagen to type III one increased. It suggested that respiratory infection induced by repeated MP may result in remodeling of pulmonary arterioles and are closely related to pulmonary hypertension.     

Sperm immobilizing activity of a synthetic bioactive peptide 20-44 of 37-kDa cationic antimicrobial protein (CAP37) of human neutrophils

We have previously reported that human sperm coincubated with human peripheral blood neutrophils in the presence of complement (C)-fixing antisperm antibody (ASA)-positive sera are rapidly internalized and degraded within the neutrophil phagolysosome. However, the mechanism by which motile sperm are processed within the phagolysosome is unknown. Various spermicidal/antimicrobial proteins contained in azurophilic granules that can be secreted into the phagolysosome may play a role in sperm disposal. In this study, we examined the expression of a 37-kDa cationic antimicrobial protein (CAP37) during sperm phagocytosis and the effect of its synthetic bioactive fragment, Peptide 20-44 (P20-44), on sperm motility, acrosomal integrity, and mitochondrial functionality. CAP37 expression by neutrophils undergoing ASA- and C-dependent sperm phagocytosis was increased as measured by flow cytometry. Exposure of motile sperm to a cationic P20-44, the bioactive antimicrobial fragment of CAP37, resulted in the loss of sperm motility without disruption of the acrosomal membrane. The sperm immobilizing activity (SIA) of P20-44 was modulated by the length of incubation, the concentration of the peptide, and the pH of the assay medium. SIA induced by P20-44 was partially reversible and was unaffected by the presence of anionic heparin or seminal plasma. Similar to the antimicrobial activity of P20-44, the SIA was also dependent on the presence of a disulfide bond between cysteine residues at positions 26 and 42 and was inhibited by Lipid A. However, the mechanism of action of P20-44 on sperm is not totally dependent on the molecule's cationicity, because five other cationic antimicrobial peptides had no detectable effect on sperm viability. Thus, the mechanism of action of P20-44 on human sperm is different from its cationic antibactericidal effect. These findings established that motile human sperm are sensitive to CAP37 or its synthetic bioactive peptide and suggested that this protein could play a role in neutrophil-mediated immune destruction of sperm in the female genital tract. P20-44 of CAP37 may be useful in investigating the regulation of human sperm motility and to construct "hybrid peptides" with enhanced potency as a component of vaginal contraceptive that could doubly be effective by killing infectious agents and inhibiting sperm transport.     

Influence of antimicrobial agents on bactericidal activity of bovine milk polymorphonuclear leukocytes

The influence of nine commonly used antibiotics on the respiratory burst activity of bovine milk polymorphonuclear leukocytes (PMNL) of high yielding cows was studied in vitro. Cellular oxidative activity was quantitated after preincubation with drugs at different concentrations and assayed by a PMA (12,13-phorbol myristate acetate)-induced luminol-enhanced chemiluminescence (CL) technique. All antibiotics except sulphadiazine and enrofloxacin decreased CL at the highest concentration. Enrofloxacin significantly increased CL. Oxytetracycline inhibited CL even at low doses. The decreased CL with danofloxacin and oxytetracycline was mainly induced by their color, which caused absorption of the blue light emitted by luminol. Production of superoxide radicals measured by the cytochrome c reduction assay was lowered by danofloxacin, penicillin and chloramphenicol. The decreased CL with ceftiofur was due to inhibition of myeloperoxidase (MPO) activity and to scavenging of reactive oxygen species. Interference with the MPO-H2O2-halide system was also observed with spiramycin, erythromycin and oxytetracycline, while the latter was also observed with penicillin. The stimulatory effect of enrofloxacin might be due to an improvement of the penetration of luminol into the PMNL or to a stimulation of the production of H2O2. Potentiation of the action of PMA by changing the ratio between bound and free intracellular Ca2+ might also be involved. Our results suggest that many antibiotics may affect neutrophil function at concentrations that may be found in milk immediately after intramammary treatment or at concentrations higher than those found in milk after intramammary treatment.     

Intrapulmonary concentrations of antimicrobial agents

The delivery of antimicrobial agents to the site of infection has always been considered important. Lung infections are typically localized to the bronchial mucosa, endothelial lining fluid, and/or alveolar macrophages. Significant advances have been made in measuring antimicrobial concentrations at these sites, although some of the methods need further refinement and standardization. Relating various intrapulmonary site concentrations to efficacy or treatment failure requires further study. This article reviews the theory and methods relating to the measurement of intrapulmonary delivery of antimicrobial agents, and compares the intrapulmonary delivery of agents commonly used for the treatment of lower respiratory infections.     

Synthetic bactericidal peptide based on CAP37: a 37-kDa human neutrophil granule-associated cationic antimicrobial protein chemotactic for monocytes

CAP37 (cationic antimicrobial protein of molecular mass 37 kDa) is a multifunctional protein isolated from the granules of human neutrophils. It is antibiotic and chemotactic and binds lipopolysaccharide. A synthetic peptide, amino acid sequence NQGRHFCGGALIHARFVMTAASCFQ, based on residues 20-44 of CAP37 protein mimics its antibiotic and lipopolysaccharide binding action. Peptide 20-44, at the concentrations tested, has antibacterial activity against Salmonella typhimurium, Pseudomonas aeruginosa, Escherichia coli, Enterococcus faecalis, and Staphylococcus aureus. The bactericidal action of the peptide was pH dependent, with maximum activity at pH 5.0 and pH 5.5 and decreased activity at pH 7.0. Various truncations, substitutions, and other modifications in the sequence deteriorate its activity. Free sulfhydryl groups and/or disulfide bridge formation are required for optimum antibiotic activity, since substitution of serines for, or alkylation of, cysteine residues 26 and 42 eliminates bactericidal activity. Evidently amino acids 20-44 represent an important, perhaps principal, antibacterial domain of CAP37. This peptide should provide new insight into the mechanism of antimicrobial activity of CAP37 and may serve as a model for new, useful, synthetic antibiotics.     

Cytofluorometric analysis of chondrotoxicity of fluoroquinolone antimicrobial agents

Betulinic acid [1] and platanic acid [2], isolated from the leaves of Syzigium claviforum, were found to be inhibitors of HIV replication in H9 lymphocyte cells. Evaluation of anti-HIV activity with eight derivatives of 1 revealed that dihydrobetulinic acid [3] was also a potent inhibitor of HIV replication. The C-3 hydroxy group and C-17 carboxylic acid group, as well as the C-19 substituents, contribute to enhanced anti-HIV activity. The inhibitory activity of these compounds against protein kinase C (PKC) was also examined, since a correlation between anti-HIV and anti-PKC activities has been suggested. However, there was no apparent correlation between anti-HIV activity and the inhibition of PKC among these compounds.     

Plasmid-mediated resistance to antimicrobial agents among listeriae

The resistance to 14 antiseptic-disinfectant and dye compounds of 208 strains of Listeria (132 L. monocytogenes, 63 L. innocua, 8 L. seeligeri, 1 L. ivanovii, 1 L. welshimeri, and 3 Listeria spp.) was tested by the agar-dilution procedure. The Listeria strains were isolated from different varieties of foods, environments of cheese dairies, humans, and wild birds. A total of 14 (6.7%) Listeria strains (12 L. monocytogenes and 2 L. innocua) were resistant to benzalkonium chloride, hexamidine diisethionate, and ethidium bromide. This multiple resistance was observed more frequently from strains of Listeria spp. detected on carcasses of poultry (47%) than strains isolated from human listeriosis cases or carriers (11.5%), red meats (10%), cheeses (5.4%), wild birds (0.9%), and environments of cheese dairies (0%). Among resistant strains, 10 groups of strains (71.5%) were differentiated by serogroup, phage typing, and sensitivity or resistance to cadmium. Extrachromosomal DNA was found in all resistant strains and was transferred at a high frequency among Listeria spp. (8.7 x 10(-6) to 1 x 10(-3) transconjugant CFUs per one donor CFU). These resistances were also transferable between L. monocytogenes and Staphylococcus aureus with similar transfer frequencies (7.8 x 10(-6) to 1 x 10(-4) and between strains of Staphylococcus aureus with similar transfer frequencies from 8 x 10(-7) to 3.3 x 10(-6). These results suggest that emergence of this multiple resistance in Listeria spp. could be due to acquisition of a replicon originating in staphylocci.     

Novel approaches to the discovery of antimicrobial agents

OBJECTIVE: To examine the cost-effectiveness of prenatal carrier screening for cystic fibrosis. METHODS: A cost-benefit equation was developed that was based on the hypothesis that the cost of prenatal diagnosis required to diagnose and prevent one case of cystic fibrosis should be equal to or less than the lifetime cost generated from the birth of a neonate with cystic fibrosis. The formula was adjusted because a woman's positive or negative carrier status remains unchanged, thus eliminating the need for testing in subsequent pregnancies. The formula was manipulated to identify the optimal cost per screening test, as well as the net cost savings per prenatally diagnosed case of cystic fibrosis for various racial or ethnic groups. Sensitivity analyses included some key assumptions regarding the cost per screening test ($50-150), patient screening acceptance rates (25-100%), and therapeutic abortion rates (50-100%). RESULTS: Assuming therapeutic abortion rates of 50-100%, the net savings per prenatally diagnosed case of cystic fibrosis are $58,369-$382,369 among whites. Given the previously reported patient screening acceptance rates of 50-78%, the overall annual cost savings in the United States for whites are $161-251 million. However, the screening program was not found to be cost-effective for blacks, Asians, or Hispanics. CONCLUSION: Under most assumptions and sensitivity analyses, a prenatal cystic fibrosis-carrier screening program appears to be cost-effective.     

Effect of addition antimicrobial agents to denture reliners

This study aimed at evaluating the incorporation of two antimicrobial drugs (nystatin and polynoxylin) as regards: the effect of the liner on the activity of the drug, determination of the least effective concentration of each drug and its duration of action, as well as assessment of the effect of the drug on the mechanical properties and the chemical composition of the liner. Results showed that nystatin added to denture liners in three different concentrations by weight (3%, 5%, 10%) acted effectively against Candida albicans, and that there was a direct relationship between concentration of Nystatin and its duration of action. The inhibitory effect of nystatin (10%) lasted for at least 32 weeks (end of study period). Furthermore, this concentration did not affect the strength properties of the liner. On the other hand, polynoxylin inhibited a number of strains of bacteria and Candida only in high concentrations (40-60%), and these concentrations adversely affected the strength properties of the liner.     

Susceptibility of anaerobic bacteria to 23 antimicrobial agents

The antimicrobial susceptibility of 492 anaerobic bacteria, the majority of which were recent clinical isolates, was determined by the agar dilution technique. Penicillin G was active against most of the strains tested at 32 U or less/ml, but only 72% of Bacteroides fragilis strains were susceptible at this level and 9% required 256 U or more/ml. Ampicillin was effective against most of the strains except B. fragilis at 16 mug or less/ml. Amoxicillin was active against only 31% of B. fragilis, 76% of other Bacteroides species, and 67% of Fusobacterium species at 8 mug/ml. Two new penicillins, mezlocillin and azlocillin, were similar to ampicillin in their activity. Carbenicillin and ticarcillin inhibited all but a few strains at 128 mug or less/ml. BLP 1654 was somewhat more active than penicillin G against B. fragilis but had similar activity against other anaerobes. Cephalothin was inactive against B. fragilis, and only 65% of other Bacteroides species were inhibited by 32 mug or less/ml. It was effective against all other anaerobes at that level. Cefamandole showed somewhat greater activity than cephalothin against B. fragilis but generally less activity against gram-positive organisms. Cefazaflur (SKF 59962) was comparable to cephalothin against B. fragilis. Cefoxitin was distinctly more active than cephalothin against B. fragilis. These latter two agents were less active than cephalothin against the gram-positive anaerobes. Chloramphenicol remains active against anaerobic bacteria at 16 mug or less/ml, with rare exceptions. Thiamphenicol was similar to chloramphenicol in its activity. Clindamycin was very active against most of the anaerobes at 8 mug or less/ml. Erythromycin and josamycin were also tested, with josamycin showing greater activity against B. fragilis than either erythromycin or clindamycin. A new oligosaccharide, everninomicin B, was less active than clindamycin against B. fragilis but more active against clostridia and some of the other strains tested. Most of the groups of bacteria tested demonstrated a trend toward resistance to tetracycline. Doxycycline and minocycline were somewhat more active than was tetracycline. Metronidazole was active against the majority of the anaerobes tested; resistance ws demonstrated by some of the gram-positive cocci and gram-positive, non-sporeforming bacilli.     

The effects of environmental conditions on the in vitro activity of selected antimicrobial agents against Escherichia coli

Serotonin (5-hydroxytryptamine, 5-HT) may play an important role in the pathogenesis of schizophrenia. Previous studies suggested that the efficacy of atypical neuroleptic drugs (e.g., risperidone and clozapine) on negative symptoms may be related to the 5-HT2a receptor. Although association studies between MspI polymorphism (T102C) and the 5-HT2a receptor gene and schizophrenia have been reported, their results are still controversial. The aim of this study was to examine the association between T102C polymorphism of the 5-HT2a receptor gene and schizophrenia as well as the association between the polymorphism and negative symptoms in a Japanese population (106 patients with schizophrenia and 109 healthy controls). No significant positive associations were observed. Our results suggest that the 5-HT2a receptor gene is not involved in the pathogenesis of schizophrenia or negative symptoms.     

In vitro activity of omeprazole in combination with several antimicrobial agents against clinical isolates of Helicobacter pylori

An agar dilution checkerboard method was used to evaluate the in vitro activity of omeprazole combined with clarithromycin, amoxicillin, and ceftibuten, respectively, against clinical isolates of Helicobacter pylori. Mueller-Hinton agar plus 5% horse blood, an inoculum of 10(6) cfu/ml, and incubation of 72 h in a CO2 atmosphere were used. With the omeprazole and clarithromycin combination, synergism was observed in 51.5% and partial synergism in 39.3% of 33 strains; with omeprazole and amoxicillin, synergism was observed in 3% and partial synergism in 60.6% of 33 strains; and with omeprazole and ceftibuten, synergism was observed in 33.3% and partial synergism in 50% of 24 strains. Antagonism between omeprazole and each antibiotic was exhibited in 0%, 6.1%, and 4.1% of these groups of strains, respectively. Of the antibiotic combinations tested, omeprazole plus clarithromycin exhibited synergism (partial or total) in the highest percentage of strains.     

Use of antimicrobial agents in patients with cardiovascular disease

Antimicrobial agents are widely utilized in the prevention and treatment of infection in patients with cardiovascular diseases. Knowledge of spectrum of activity, pharmacology, adverse effect and toxicity profile, and emergence of resistant pathogens is critical to the appropriate use of these agents. The following review will emphasize the safe, effective use of antimicrobial drugs in the cardiovascular patient.     

Microbiologic assay for detection of antimicrobial agents in urine

Antimicrobial therapy can be a confounding factor in the diagnosis of urinary tract infection and is not always reported to laboratories by physicians. We developed a microbiologic assay for screening urine specimens for antimicrobial agents. Bacillus stearothermophilus was used as the indicator bacteria. A total of 1,921 urine specimens from three hospitals in Taiwan were screened using this assay. Of the samples assayed, 1,293 were positive for antimicrobial agents. Agreement between information provided by physicians and laboratory findings was 68.5% (419/612). In the presence of antimicrobial agents in the urine samples, the isolation of yeasts and Pseudomonas aeruginosa increased dramatically, from 4.5 to 19.5% and 4.2 to 13.2%, respectively. Additionally, Escherichia coli was more resistant to gentamicin (75.3% vs 48.7%, p < 0.0001), norfloxacin (85.2% vs 64.6%, p = 0.0006) and co-trimoxazole (58.5% vs 35.5%, p = 0.0018). In view of the high rate of occurrence of antimicrobial agents in urine specimens and the lack of information provided by most physicians to laboratories, a screening method to detect the presence (or absence) of antimicrobials in urine specimens may be a useful tool particularly in areas such as Taiwan where antimicrobial agents are commonly abused.     

Purification of an antimicrobial peptide from rabbit aqueous humour

PURPOSE: To identify an antimicrobial factor previously demonstrated in rabbit aqueous humour. METHODS: Rabbit aqueous humour was fractionated by a multi-stage process involving anion-exchange and size-exclusion liquid chromatography. The antimicrobial effect of aqueous humour fractions upon Staphylococcus aureus were evaluated in an in vitro model. The components of aqueous humour fractions mediating an antimicrobial effect were investigated by SDS-PAGE. RESULTS: A single peptide of molecular weight approximately 8 kDa was identified which mediated an antimicrobial effect upon Staphylococcus aureus. Attempts to identify the peptide have been unsuccessful. CONCLUSIONS: Rabbit aqueous humour contains an unidentified peptide that mediates an antimicrobial effect upon Staphylococcus aureus. If such a peptide is present in human aqueous humour it may contribute to the apparent resistance to bacterial infection manifest in the anterior chamber.     

In vitro activities of antimicrobial agents against Candida species

A single surgeon's consecutive series of 50 arthroscopically repaired meniscal tears in 48 patients was retrospectively reviewed. None of these patients had concomitant ligament damage to the knee. The average follow-up period was 10 years, 9 months. Criteria for clinical success included 1) history of pain of grade 1 or less and absence of locking, catching, or giving way; 2) a physical examination demonstrating no significant effusion and a painless and negative jump sign; and 3) no subsequent surgical procedures on the repaired meniscus. Patient satisfaction was quite high, although clinical confirmation was possible in only 38 knees, indicating a clinical success rate of 76%. Bilateral standing radiographs were obtained on these 38 operated knees and were evaluated using Fairbank's classification. Evaluation of the radiographs revealed that 8% of the operated knees had minimal joint changes, as compared with 3% in the contralateral, nonoperated knee. This study demonstrates that arthroscopic meniscal repair in knees with isolated meniscal tears has the potential for a long-term successful clinical and radiographic outcome.     

Comparative antimicrobial activity and kill-curve investigations of novel ketolide antimicrobial agents (HMR 3004 and HMR 3647) tested against Haemophilus influenzae and Moraxella catarrhalis strains

TNF-alpha-treated osteosarcoma cells have an enhanced susceptibility to NK lysis which mostly depends on the increased expression of CD54 molecules. Since IL-1 and IL-6 share overlapping biological properties with TNF-alpha, we investigated whether the treatment of osteosarcoma cells with these cytokines could modify their susceptibility to NK lysis and whether these modifications were related to a different distribution of CD54, CD56 and CD58 molecules. We demonstrated that the expression of CD54 and CD58 on osteosarcomas correlated positively with the susceptibility to NK lysis and that this susceptibility was enhanced by TNF-alpha treatment but not by IL-1 and IL-6 stimulation.