Chlamydia pneumoniae IgA- and IgG antibodies in young survivors of myocardial infarction. A comparison of antibody detection by a microimmunofluorescence test and an enzyme immunoassay.

OBJECTIVES: Chronic Chlamydia pneumoniae infection is considered as a cardiovascular risk factor and antibodies are commonly analysed by the subjective microimmunofluorescence (MIF) test. We wanted to investigate the C. pneumoniae IgA- and IgG seroprevalence in young survivors of myocardial infarction and matched controls, and to compare the agreement of detecting antibodies between a MIF test and an enzyme immunoassay (EIA). DESIGN: A total of 61 patients hospitalized as a result of myocardial infarction, 51 patients hospitalized with chest pain and negative exercise-ECG and 61 age and sex matched controls (mean age 53.3 years, range 40-60 years) were included in this case-control study. Serological comparisons were expressed as sensitivity, specificity and interrater agreement (K or Kw) of the EIA test related to the MIF test. RESULTS: Presence of IgA (cut off = 16) antibodies was significantly higher in coronary heart patients compared with controls for both assays (P = 0.02 by the MIF and P = 0.05 by the EIA test). The presence of IgG (cut off = 32) antibodies was significantly higher amongst patients (P = 0.05) when analysed by the MIF-test, but not with the EIA-test (P = 0.16). The strength of agreement between the assays was good for both IgA- (Kw = 0.67) and IgG (Kw = 0.79) analyses. However, only 52.8% of the IgA samples classified as strong positive (cut-off = 32) by the MIF test were strong positive by the EIA test (K = 0.56). Only 73.2% of the negative IgG samples (<32) by the MIF-test turned out negative by the EIA-test (K = 0.73). CONCLUSIONS: Dependent on assay and cut-off level, there is an increased C. pneumoniae IgA- and IgG seroprevalence in young survivors of myocardial infarction compared with controls. Despite the subjective interpretation of MIF-titres, the strength of agreement between the EIA and MIF tests was good for both antibody classes. However, misclassification of highly positive IgA samples and negative IgG samples by the MIF test may influence study conclusions. We conclude that the choice of serological method is of major importance when evaluating a possible relationship between C. pneumoniae and coronary heart disease.

The antimicrobial peptides lactoferricin B and magainin 2 cross over the bacterial cytoplasmic membrane and reside in the cytoplasm.

The localization of immunolabelled antimicrobial peptides was studied using transmission electron microscopy. Staphylococcus aureus and Escherichia coli were exposed to lactoferricin B (17-41), lactoferricin B (17-31) and D-lactoferricin B (17-31). E. coli was also exposed to cecropin P1 and magainin 2. The lactoferricins were found in the cytoplasm of both bacteria. In S. aureus the amount of cytoplasmic lactoferricin B (17-41) was time- and concentration-dependent, reaching a maximum within 30 min. Cecropin P1 was confined to the cell wall, while magainin 2 was found in the cytoplasm of E. coli. The finding of intracellularly localized magainin is not reported previously.

Post-antibiotic effect of the antimicrobial peptide lactoferricin on Escherichia coli and Staphylococcus aureus.

Lactoferricin is an antimicrobial peptide generated by gastric pepsin cleavage of lactoferrin. A possible post-antibiotic effect (PAE) of bovine lactoferricin (Lfcin B) and two shorter peptide derivatives against Staphylococcus aureus and Escherichia coli was studied. A drug removal technique involving centrifugation and washing was used. No PAE was found for Lfcin B against these two bacteria. The shorter derivatives had a short PAE against E. coli. They had a short negative PAE against S. aureus. In conclusion, the overall PAE is not overwhelming, but the small differences found between the different peptide-bacteria combinations could indicate that different peptide mechanisms of action might be present.

Remarkable attachment of lactoferrin to Streptococcus pyogenes during acute pharyngotonsillitis.

The purpose of this study was to establish whether lactoferrin (hLf) attached to Streptococcus pyogenes, one causative agent of acute pharyngotonsillitis (AT), during the course of the disease. Bacterial samples were obtained from the tonsillar surfaces of 7 patients (6 females, 1 male; median age 26 years; range 16-50 years) suffering from AT who were culture-positive for S. pyogenes and from 5 healthy adult controls who were culture-negative for this pathogen. Using gold-labelled antiserum against S. pyogenes and hLf, this pathogen and other bacteria on the tonsillar surfaces coated with hLf could be identified by tracing the gold particles in a transmission electron microscope. In healthy adults, 8% (median value; range 6-12%) of the surface tonsillar bacteria were coated with hLf. In AT patients, 59% (median value; range 42 67%) of S. pyogenes were coated with hLf, in contrast to 9% (median value; range 0-26%) of all other bacteria (p < 0.01). This study hints that hLf might participate in recovery from AT in several ways, e.g. by binding to the S. pyogenes pathogens, in addition to its well-known virtue of iron-binding capacity.

Bactericidal kinetics of 3 lactoferricins against Staphylococcus aureus and Escherichia coli.

Bovine lactoferricin is an antimicrobial, cationic peptide generated upon gastric pepsin cleavage of bovine lactoferrin. We investigated the bactericidal effects of native lactoferricin [Lfcin B(17-41)], a shortened derivative [Lfcin B(17-31)] and the all-D-amino acid counterpart of Lfcin B(17-31) against Escherichia coli and Staphylococcus aureus. The results revealed different activities for the peptides against Gram-positive and -negative bacteria. D-Lfcin B(17-31) was the most efficient peptide against E. coli. The same peptide showed improved activity against S. aureus, D-Lfcin B(17-31) showed a significant better efficacy when compared to the L-form, but not when compared to Lfcin B(17-41). There was no correlation between the bactericidal concentrations and the time needed to achieve maximum effect. This indicates the importance of structural differences between the peptides and/or bacteria and implies that the simple thesis of I antibacterial target is not valid for lactoferricin.

Lactoferrin and cyclic lactoferricin inhibit the entry of human cytomegalovirus into human fibroblasts.

Lactoferrin is mainly produced by polymorphonuclear leukocytes and has been demonstrated in mammalian milk and external secretions. Lactoferrin is an iron-binding, multifunctional protein and may play an important role in immune regulation and in defense mechanisms against bacteria, fungi and viruses. Lactoferricin is a potent antimicrobial peptide generated from the N-terminal part of lactoferrin by pepsin cleavage. We demonstrate that lactoferrins from different species and its N-terminal peptide lactoferricin (particularly the cyclic form) inhibit expression of early and late antigens, as well as production of infectious viral progeny during human cytomegalovirus (HCMV) infection in vitro. Iron-saturated lactoferrin did not affect HCMV antigen expression. Heparin had the same effects as iron-depleted lactoferrin. Yet, mixtures of lactoferrin and heparin did not inhibit HCMV multiplication i.e. lactoferrin and heparin seemed to mutually block each other's antiviral activities. HCMV-infected cells exposed to lactoferrin and cyclic lactoferricin contained less intracellular virus than unexposed cells. The antiviral activity of cyclic lactoferricin was more than seven-fold weaker than that of the maternal molecule. Lactoferrin and cyclic lactoferricin prevented HCMV entrance into the host cell.

Lactoferricin B causes depolarization of the cytoplasmic membrane of Escherichia coli ATCC 25922 and fusion of negatively charged liposomes.

Antimicrobial peptides have been extensively studied in order to elucidate their mode of action. Most of these peptides have been shown to exert a bactericidal effect on the cytoplasmic membrane of bacteria. Lactoferricin is an antimicrobial peptide with a net positive charge and an amphipatic structure. In this study we examine the effect of bovine lactoferricin (lactoferricin B; Lfcin B) on bacterial membranes. We show that Lfcin B neither lyses bacteria, nor causes a major leakage from liposomes. Lfcin B depolarizes the membrane of susceptible bacteria, and induces fusion of negatively charged liposomes. Hence, Lfcin B may have additional targets responsible for the antibacterial effect.

[What makes bacteria pathogenic?]. / Hva gjør bakterier patogene?

Pathogenicity represents a form of specialization that enables certain microorganisms to replicate within specific animals and damage host cells. The outcome is as dependent on the host as it is upon the properties of the pathogen. The ability of the human body to prevent most of the bacteria it encounters from doing harm is the result of an evolutionary course that has produced a complex set of overlapping defenses. The non-specific defenses include antibacterial substances such as complement, phagocytic cells, and the washing action of fluids such as saliva and urine. The specific defenses are cells producing antibodies upon stimulation, and cytotoxic cells. The non-specific defenses are the host's only defenses in the critical early period when infection develops, thus it is not surprising that many of the characteristics allowing certain types of bacteria to cause infection are characteristics that allow them to evade the non-specific defenses of the body. They include factors that help the bacteria to adhere to and invade cells and tissues. Some bacteria are well equipped to evade the body's defense mechanisms, and some produce toxins that cause symptoms and disease. The production of virulence factors is finely tuned and regulated.

[Natural antimicrobial peptides--promising new antibiotics or a problem later on?]. / Naturlig forekommende antimikrobielle peptider--lovende nye antibiotika, eller ris til egen bak?

BACKGROUND: Antimicrobial proteins and peptides are important elements of host defence that are found in virtually all living species examined so far. MATERIAL AND METHODS: This review is based on the author's own research and a search of Medline (key words: antimicrobial peptides, biochemistry, mode of action, resistance). RESULTS: In animals, antimicrobial peptides are found on mucosal epithelial surfaces, in body fluids and in the microbicidal organelles of phagocytic cells. The peptides vary in size, structure and activity, but most are amphiphilic and positively charged. They act on a broad range of bacteria, fungi, viruses, parasites and certain tumour cells. Cationic peptides can be classified into several groups on the basis of sequence similarities, secondary and tertiary structure, function and origin. Their main acting mechanism is thought to be the disruption of the cytoplasmic membrane which kill bacteria swiftly and thoroughly. INTERPRETATION: Antimicrobial peptides are promising novel antibiotic candidates for clinical use, topically as well as systemically. So far, development of resistance against antimicrobial peptides has not been a problem, but this will have to be monitored closely in the years ahead.

[Guidelines for diagnosis and treatment of sore throat]. / Retningslinjer for diagnostikk og behandling av sår hals.

BACKGROUND: Available guidelines for the diagnosis and treatment of sore throat give conflicting recommendations. Our aim was to develop evidence-based guidelines. MATERIAL AND METHODS: We searched The Cochrane Library, Medline and other sources for systematic reviews and other evidence that met explicit inclusion criteria for all of the relevant options and outcomes we identified. The validity of included studies was assessed. Draft recommendations based on assessment of this evidence were widely circulated and discussed in focus groups with patients and physician assistants. RESULTS: Throat infections are self-limiting and complications rare. Penicillin shortens the duration of symptoms in tonsillitis caused by beta-haemolytic streptococci and reduces the risk of complications. Penicillin has adverse effects and increases the risk of reinfections. Patients with sore throat should usually be treated without antibiotics. Visiting a physician is normally unnecessary. Antibiotics should be considered in serious cases or if the patient prefers this, but should only be prescribed for throat infections caused by beta-haemolytic streptococci. The diagnosis should be based on clinical criteria and a rapid antigen test in cases of doubt. INTERPRETATION: Benefits of antibiotics must be weighed against harms. Patients should be given good information and involved in decision/making if they want antibiotics.

[Guidelines for diagnosis and treatment of acute urinary tract problems in women]. / Retningslinjer for diagnostikk og behandling av akutte vannlatingsplager hos kvinner.

BACKGROUND: Available guidelines for the management of symptoms of lower urinary tract infections (UTI) in women give conflicting recommendations. MATERIAL AND METHODS: We searched The Cochrane Library, Medline and other sources for evidence that met explicit inclusion criteria for the relevant options and outcomes identified. The validity of included studies was assessed. Draft recommendations were widely circulated and discussed in focus groups with patients and physician assistants. RESULTS: The probability that a woman with dysuria or frequency has bacteriuria, is 80%. The probability of UTI given a negative result of a dipstick test is 50%. Evidence suggests that antibiotics will rapidly relieve symptoms, but there are limited data from placebo-controlled randomised trials. Population based studies show that many women do not visit physicians for symptoms of UTI. Women with symptoms of UTI can be treated with antibiotics without examination of the urine. Women with earlier episodes of UTI can be offered treatment by telephone. Antibiotics for three days is sufficient based on eradication of bacteriuria. Women should be seen by a physician if the symptoms are atypical. INTERPRETATION: Implementing these guidelines could result in better service to women with UTIs. More evidence about the effects of antibiotics and other treatments is needed.

[Guidelines for diagnosis and treatment of sore throat]. / Retningslinjer for diagnostikk og behandling av sår hals.

BACKGROUND: Available guidelines for the diagnosis and treatment of sore throat give conflicting recommendations. Our aim was to develop evidence-based guidelines. MATERIAL AND METHODS: We searched The Cochrane Library, Medline and other sources for systematic reviews and other evidence that met explicit inclusion criteria for all of the relevant options and outcomes we identified. The validity of included studies was assessed. Draft recommendations based on assessment of this evidence were widely circulated and discussed in focus groups with patients and physician assistants. RESULTS: Throat infections are self-limiting and complications rare. Penicillin shortens the duration of symptoms in tonsillitis caused by beta-haemolytic streptococci and reduces the risk of complications. Penicillin has adverse effects and increases the risk of reinfections. Patients with sore throat should usually be treated without antibiotics. Visiting a physician is normally unnecessary. Antibiotics should be considered in serious cases or if the patient prefers this, but should only be prescribed for throat infections caused by beta-haemolytic streptococci. The diagnosis should be based on clinical criteria and a rapid antigen test in cases of doubt. INTERPRETATION: Benefits of antibiotics must be weighed against harms. Patients should be given good information and involved in decision-making if they want antibiotics.

Lactoferrin: a multifunctional glycoprotein.

Lactoferrin is an iron-binding glycoprotein found in milk, exocrine secretions of mammals, and in secondary granules from polymorphonuclear neutrophils. This review describes the wide spectrum of functions ascribed to lactoferrin, with special emphasis on the antimicrobial properties of this protein, and its derived peptides.

Initial binding sites of antimicrobial peptides in Staphylococcus aureus and Escherichia coli.

We examined the initial binding sites of magainin 1, cecropin P1 and lactoferricin B in Staphylococcus aureus and Escherichia coli. All 3 peptides were active against E. coli, whereas only lactoferricin B exerted any activity against S. aureus. Soluble lipoteichoic acid and lipopolysaccharide both interacted with all 3 peptides, whereas soluble teichoic acid interacted with lactoferricin B only. Antibodies against teichoic acid diminished the activity of lactoferricin B, while antibodies against lipoteichoic acid had no influence on the activity of lactoferricin B. Antibodies against lipopolysaccharide diminished the activity of lactoferricin B and magainin 1, but had no effect on the activity of cecropin P1 against E. coli. We conclude that the initial binding sites of lactoferricin B in S. aureus, and of lactoferricin B and magainin 1 in E. coli, are teichoic acid and lipopolysaccharide, respectively. Cecropin P1 seems to interact with a different binding site than those of magainin 1 and lactoferricin B in E. coli.

Interference of the antimicrobial peptide lactoferricin B with the action of various antibiotics against Escherichia coli and Staphylococcus aureus.

The antimicrobial peptide, lactoferricin, can be generated upon gastric pepsin cleavage of lactoferrin. We have examined the interaction of lactoferricin of bovine origin, Lf-cin B, with the antibiotics penicillin G, vancomycin, gentamicin, colistin, D-cycloserine and erythromycin against E. coli ATCC 25922 and Staphylococcus aureus ATCC 25923. We demonstrated synergism between Lf-cin B and erythromycin against E. coli, and partial synergism between Lf-cin B and penicillin G, vancomycin and gentamicin against E. coli. Only penicillin G acted in partial synergism with Lf-cin B against S. aureus. Lf-cin B antagonized vancomycin and gentamicin against S. aureus in low concentration. We conclude that Lf-cin B may facilitate the uptake of antibiotics across the cell envelope.

Antibacterial effects of lactoferricin B.

The antimicrobial peptide, lactoferricin, can be generated upon gastric pepsin cleavage of lactoferrin. We have examined the inhibitory efficacy of lactoferricin of bovine origin (Lf-cin B) on Escherichia coli, Proteus mirabilis and Staphylococcus aureus with or without a cell wall. We found that spheroplasts and protoplasts had a lower MIC than their counterparts with a cell wall. We also compared the efficacies of Lf-cin B (17-31) made of all L-amino acids and all D-amino acids. The peptide made of all D-amino acids was more active than the corresponding L-enantiomer. Furthermore, we examined the influence of Lf-cin B on the motility of E. coli and the influence of temperature on the susceptibility of bacteria exposed to Lf-cin B. Bacteria exposed to sub-MIC of Lf-cin B lost their motility. Bacteria exposed to Lf-cin B at 20 degrees C were more sensitive to Lf-cin B than when exposed at 37 degrees C. These findings indicate that the cell envelope is a limiting step for Lf-cin B to exert its antibiotic effect. We cannot rule out a receptor-mediated first step for Lf-cin B (17-31).

Lactoferricin of bovine origin is more active than lactoferricins of human, murine and caprine origin.

The antimicrobial peptide lactoferricin is generated by gastric pepsin cleavage of lactoferrin. We have examined the antimicrobial activity of lactoferricins derived from lactoferrin of human, murine, caprine and bovine origin with minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) against E. coli ATCC 25922 and S. aureus ATCC 25923. We found that lactoferricin of bovine origin (Lf-cin B) was the most efficacious of the lactoferricins tested. By comparing the linear and cyclic Lf-cin B we found the cyclic peptide to be the most active. Lactoferricin B was moderately active against E. coli ATCC 25922 and S. aureus ATCC 25923, but had no activity against P. mirabilis or Y. enterocolitica. Lf-cin B showed good activity against C. albicans, C. tropicalis and C. neoformans.

Viable fungi in indoor air in homes and schools in the Sør-Varanger community during winter.

The present study investigated the content of fungal aerospores in homes and schools of house-dust-mite (HDM)-sensitized and control children in a subarctic area. During winter, airborne microfungi were collected from the homes and schools of 19 HDM-sensitized children and 19 nonatopic controls, all living in the community of Sør-Varanger, northern Norway. The samples were cultivated and microfungal growth was identified microscopically. Indoor humidity, temperature, and carbon dioxide (CO2) concentrations were measured. Housing conditions and sociodemographic and symptom data were obtained by a questionnaire. Penicillium was the most common microfungus in both homes and schools, followed by various yeasts, Aspergillus, Cladosporium, and Mucor. The number of infected homes was equal in the HDM-sensitized group and the control group, but aerospore counts were higher in the HDM-sensitized group than in the control group. The lowest aerospore counts were found in the schools. High aerospore counts also appeared to be related to high indoor humidity. The keeping of pets and damp indoor conditions were more frequent in homes of HDM-sensitized children than in the control group, whereas parental smoking and carpeting occurred with equal frequency in both groups. This indicates that no allergy sanitation measures had been undertaken, especially in the homes of the HDM-sensitized children.