Effect of azithromycin plus rifampin versus amoxicillin alone on eradication and inflammation in the chronic course of Chlamydia pneumoniae pneumonitis in mice

Impact of azithromycin, doxycycline and redox-active small molecules on amoxicillin-induced Chlamydia pneumoniae persistence

Amoxicillin is recommended as primary treatment for community-acquired bacterial pneumonia (CABP). 5-10% of CABP cases are caused by Chlamydia pneumoniae, an obligate intracellular bacterium which responds to beta-lactam antibiotics by converting to a persistent phenotype. To support rational pharmacotherapy of C. pneumoniae infections, we investigated how clinically relevant concentrations of azithromycin and doxycycline affect amoxicillin induced C. pneumoniae persistence. Given the known role of redox state alterations in the action of bactericidal antibiotics and widespread use of redox-active dietary supplements when experiencing respiratory symptoms, we also studied how redox active compounds affect the studied antibiotic treatments. Our data demonstrate that clinically applied amoxicillin concentrations (10 and 25 mg/l) fail to eradicate C. pneumoniae infection in respiratory epithelial cells. Transmission electron microscopy (TEM) of amoxicillin-treated C. pneumoniae infected cells reveal aberrant bacterial morphology characteristic of chlamydial stress response. Amoxicillin was also found to significantly limit the antichlamydial effect of azithromycin or doxycycline. However, based on quantitative culture and quantitative PCR data, azithromycin was superior to doxycycline in C. pneumoniae eradication either as monotherapy or in combination with amoxicillin. Amoxicillin was also found to decrease respiratory epithelial cell glutathione (GSH) levels, whereas redox-active dibenzocyclooctadiene lignans increased C. pneumoniae load in amoxicillin-treated cultures up to two-fold. These data highlight the impact of relative administration time on the efficacy of antichlamydial antibiotics and indicate unfavorable interactions between amoxicillin and redox-active small molecules.

Subantibiotic dose of azithromycin attenuates alveolar bone destruction and improves trabecular microarchitectures in a rat model of experimental periodontitis: A study using micro-computed tomography

Azithromycin, a macrolide antibiotic, has anti-inflammatory and immunomodulatory activities apart from its antibacterial properties. In this study, we examined the efficacy of subantibiotic dose of azithromycin on ligature-induced periodontitis in rats using micro-computed tomography (micro-CT) imaging and bone parameter analysis. Male Sprague-Dawley rats were allocated to the following four groups: non-ligation (NL) group; ligation-only (L) group; ligation-plus-subantibiotic dose azithromycin (SA) group; and 4) ligation-plus-antibiotic dose azithromycin (AA) group. The rats from Groups L, SA and AA were subjected to periodontitis by placing a ligature around lower right first molar. Immediately after ligation, the rats in SA and AA groups received daily intraperitoneal injections of azithromycin at a dosage of 3.5 or 10mg/kg body weight, respectively. The ligatures were maintained for 2weeks at which time the rats had their mandibles hemisected for micro-CT analysis. Subantibiotic dose of azithromycin strongly suppressed reductions in alveolar bone height and bone volume fraction caused by experimental periodontitis. When subantibiotic dosage of azithromycin was administered to rats, ligature-induced alterations in microarchitectural parameters of trabecular bone were significantly reversed. Rats treated with subantibiotic dose of azithromycin presented no significant difference compared to rats with antibiotic dosage in all parameters. While further studies are necessary, subantibiotic dose of azithromycin could be utilized as a host modulator for the treatment of periodontitis.

Causality of Chlamydiae in Arthritis and Spondyloarthritis: a Plea for Increased Translational Research

Current molecular genetic understanding of the metabolically active persistent infection state of Chlamydia trachomatis and Chlamydia pneumoniae in the synovium in patients with arthritis and spondyloarthritis favors a causal relationship. Here, we examine how adequately the accepted criteria for that etiologic relationship are fulfilled, emphasizing the situation in which these microorganisms cannot be cultivated by standard or other means. We suggest that this unusual situation of causality by chlamydiae in rheumatic disease requires establishment of a consensus regarding microorganism-specific terminology as well as the development of new diagnostic and classification criteria. Recent studies demonstrate the value of molecular testing for diagnosis of reactive arthritis, undifferentiated spondyloarthritis, and undifferentiated arthritis caused by C. trachomatis and C. pneumoniae in clinical practice. Data regarding combination antibiotic therapy is consistent with the causative role of chlamydiae for these diseases. Observations of multiple intra-articular coinfections require more research to understand the implications and to respond to them.

Chlamydia muridarum enters a viable but non-infectious state in amoxicillin-treated BALB/c mice

In culture, exposure to penicillin and other stressors induce chlamydiae to enter a non-infectious but viable state termed persistence. Chlamydiae may reenter their normal developmental cycle after stressor removal. Though aberrant RB similar to those present in culture models of persistence have been observed within infected tissues, the existence of persistent chlamydiae has not been definitively demonstrated in vivo. As a result, the role of persistent organisms in pathogenesis is undefined. In order to establish an experimentally tractable model of in vivo persistence, Chlamydia muridarum vaginally-infected mice were gavaged with either water or amoxicillin (amox). Vaginal swabs were collected for chlamydial titration and RNA isolated for quantification of pre-16s rRNA. Uterine tissue was analyzed by transmission electron microscopy (TEM). Although amox-treatment reduced vaginal shedding by >99%, C. muridarum pre-16s rRNA accumulation was unchanged by treatment. These data indicate that the amox-exposed organisms were viable but not infectious. Furthermore, TEM analyses demonstrated that inclusions in amox-treated animals contained primarily large, aberrant RB, but those observed in untreated control animals were normal. Collectively, these data suggest that amoxicillin treatment induces C. muridarum to enter the persistent state in vivo. This model also represents the first experimentally tractable animal model of chlamydial persistence.

Macrolide therapy in chronic inflammatory diseases

Macrolides are a group of antibiotics with a distinctive macrocyclic lactone ring combined with sugars (cladinose, desosamine). The action of macrolides is to block protein synthesis by binding to the subunit of 50S ribosome of bacteria. Prototype macrolide was erythromycin, which came into clinical practice in the 50s of the 20th century. Its antimicrobial spectrum covers the scope of the penicillins but is extended to the impact of atypical bacteria. In the 90s more drugs of this group were synthesized—they have less severe side effects than erythromycin, extended spectrum of Gram-negative bacteria. Macrolides are effective in treating mycobacterial infections especially in patients infected with HIV. It is now known that in addition to antibacterial abilities, macrolides have immunomodulatory effects—they inhibit the production of proinflammatory cytokines (TNF, IL1, 6, and 8) affect transcription factors (NF-κB) as well as costimulaton (CD 80) and adhesion molecules (ICAM). This review article focused not only on the their antimicrobial abilities but also on efficacy in the treatment of several inflammatory disorders independent of the infectious agent. Their wider use as immunomodulators requires further study, which can lead to an extension of indications for their administration.

2010 European guideline for the management of Chlamydia trachomatis infections

This guideline aims to provide comprehensive information regarding the management of infections caused by Chlamydia trachomatis in European countries. The recommendations contain important information for physicians and laboratory staff working with sexually transmitted infections (STIs) and/or STI-related issues. Individual European countries may be required to make minor national adjustments to this guideline as some of the tests or specific local data may not be accessible, or because of specific laws.

Inhibitory effect of the natural product betulin and its derivatives against the intracellular bacterium Chlamydia pneumoniae

Chlamydia pneumoniae is a universal pathogen that has been indicated to play a part in the development of asthma, atherosclerosis and lung cancer. The complete eradication of this intracellular bacterium is in practice impossible with the antibiotics that are currently in use and studies on new antichlamydial compounds is challenging because Chlamydia research lacks the tools required for the genetic modification of this bacterium. Betulin is a natural lupane-class triterpene derived from plants with a wide variety of biological activities. This compound group thus has wide medical potentials, and in fact has been shown to be active against intracellular pathogens. For this reason, betulin and its derivatives were selected to be assayed against C. pneumoniae in the present study. Thirty-two betulin derivatives were assayed against C. pneumoniae using an acute infection model in vitro. Five promising compounds with potential lead compound characteristics were identified. Compound 24 (betulin dioxime) gave a minimal inhibitory concentration (MIC) of 1 microM against strain CWL-029 and showed activity in nanomolar concentrations, as 50% inhibition was achieved at 290 nM. The antichlamydial effect of 24 was confirmed with a clinical isolate CV-6, showing a MIC of 2.2 microM. Previous research on betulin and its derivatives has not identified such a remarkable inhibition of Gram-negative bacterial growth. Furthermore, we also demonstrated that this antichlamydial activity was not due to PLA(2) (EC 3.1.1.4) inhibition caused by the betulin derivatives.

Intermittent azithromycin treatment for respiratory symptoms in patients with chronic chlamydia pneumoniae infection

Chlamydia pneumoniae (Cpn) is a common respiratory pathogen with a biphasic replicative cycle and has a tendency to cause chronic infections. Azithromycin is commonly used for the treatment of Cpn infections, but little is known about the optimal dose and duration of therapy. In this prospective double-blind, randomized study the effects of azithromycin and placebo were compared regarding longstanding airway and/or pharyngeal symptoms in patients with chronic Cpn infection. Further, effects on antibody titres and lung function were assessed. 103 patients were treated with either azithromycin 500 mg daily for 5 d, repeated 3 times with a 23-d interval, or placebo. Patients were examined 4 months and 1 y after completed treatment. Evaluation of symptoms showed general improvement and less hawking in patients treated with azithromycin compared to placebo after 4 months, but there was no sustained difference 1 y after completed treatment. The antibody titres remained stable, and there was no influence on lung function. Adverse events, primarily gastrointestinal, were more frequently reported with azithromycin than placebo. In conclusion, azithromycin was effective for reduction of respiratory symptoms in patients with chronic Cpn infection, but prolonged intermittent treatment with high doses did not eradicate the chronic infection.

Chlamydia pneumoniae infection after lung transplantation

BACKGROUND

Chlamydia pneumoniae is established as a common agent of acute respiratory tract infection and has been implicated in the pathogenesis of asthma and chronic obstructive pulmonary disease. Airway disease is a prominent cause of morbidity and mortality after lung transplantation. We investigated the role of C pneumoniae as a pulmonary pathogen after lung transplantation.

METHODS

Eighty lung transplant recipients underwent 232 bronchoscopies with bronchoalveolar lavage with or without transbronchial lung biopsy during 1 year for surveillance of rejection and infection, or where clinically indicated.

RESULTS

C pneumoniae was detected using nested polymerase chain reaction in 9 of 36 (25%) recipients studied within 30 days of lung transplantation, 3 of whom remained positive on repeat lavage and died from airway disease in the first year post-operatively. By comparison, all 27 recipients with negative lavage survived >1 year. Lavage was positive for C pneumoniae in 18 of 71 (25%) recipients studied >30 days after lung transplantation, 5 of whom had pneumonia and 8 of whom had bronchiolitis obliterans syndrome. Eleven also had acute pulmonary allograft rejection.

CONCLUSIONS

Persistent infection with C pneumoniae (whether donor-derived, de novo or re-activated) appears deleterious to pulmonary allograft function and is associated with early mortality, rejection and bronchiolitis obliterans syndrome after lung transplantation. A trial of empiric antibiotic therapy for C pneumoniae may therefore be warranted in the attempt to prevent progressive inflammatory airway disease.

Inhibitory effect of dietary phenolic compounds on Chlamydia pneumoniae in cell cultures

Chlamydial infections are very common worldwide. All chlamydial species have a tendency to cause persistent infections, which have been associated to several chronic diseases including blinding trachoma, infertility and coronary heart disease (CHD). At present, no efficient treatment for the eradication of chronic chlamydial infections exists and, thus, new antichlamydial compounds are urgently needed. This study was designed to screen antichlamydial activity of natural flavonoids and other natural and structurally similar synthetic compounds against Chlamydia pneumoniae in human cell line (HL). HL cells were infected with C. pneumoniae and incubated 72 h with studied compounds. Reduction in the number of inclusions was determined with immunofluorescence staining. In vitro minimum inhibitory concentration was also determined for some of the most active compounds. Thirty seven percentage of the studied compounds (57 in total) were highly active against C. pneumoniae and all the studied compounds were non-toxic to the host cells at studied concentrations. Our study revealed direct antichlamydial effect for selected polyphenolic compounds against C. pneumoniae, in vitro. We also demonstrated the ability of some of the investigated compounds to accumulate inside cells or into cell membranes and cause inhibition, even when present only prior to infection.

Microbiologic and immunologic evaluation of a single high dose of azithromycin for treatment of experimental Mycoplasma pneumoniae pneumonia

We evaluated the efficacy of azithromycin therapy given as a single high dose or divided over 5 days for the treatment of mild experimental Mycoplasma pneumoniae pneumonia. Although both azithromycin regimens significantly reduced quantitative cultures, lung histopathology, and pulmonary cytokines and chemokines, there were no significant differences between the two regimens.

Septic pleuritis and abdominal abscess formation caused by Rhodococcus equi in a foal

A 3-month-old female Arabian horse was evaluated because of fever, respiratory distress, lethargy, and decreased appetite of 5 days' duration. Pleural effusion was diagnosed on the basis of ultrasonographic and radiographic examinations. Cytologic examination of pleural fluid collected via thoracocentesis revealed septic inflammation; bacteriologic culture of a sample of that fluid yielded Rhodococcus equi. A large intra-abdominal mass adjacent to the body wall was identified ultrasonographically. A specimen of the mass was collected via aspiration; the specimen was identified cytologically as purulent exudate that contained large numbers of rod-shaped bacteria, which confirmed abdominal abscess formation. Bacteriologic culture of a sample of the exudate also yielded R. equi. The foal was treated with azithromycin (10 mg/kg [4.5 mg/lb], PO, q 24 h for 5 days then q 48 h) and rifampin (5 mg/kg [2.3 mg/lb], PO, q 12 h) for 8 weeks and metronidazole (15 mg/kg [6.8 mg/lb], PO, q 8 h) for 3 weeks. Clinically, the foal responded to antimicrobial treatment within 2 weeks. At 8 weeks after the initial evaluation, ultrasonographic examination of the foal revealed resolution of the pleural effusion and abdominal abscess. In foals, R. equi infection typically results in pyogranulomatous pneumonia, and pleural effusion is an uncommon clinical sign. The combination of azithromycin and rifampin appears to be an effective treatment for R. equi infection in foals.

Immunomodulatory effects of antimicrobials in the therapy of respiratory tract infections

PURPOSE OF REVIEW

Several classes of antibiotics, particularly macrolides and to some extent quinolones, exert modulatory effects on inflammatory cells. With a growing number of experimental and clinical studies being performed, the relevance of the immunomodulatory actions of antibiotics to the therapy of respiratory infections is discussed in the light of recent reports.

RECENT FINDINGS

Antibiotics, particularly macrolides, exert both stimulatory and inhibitory effects on leukocytes. These effects seem to be related to the activation state of the leukocytes, facilitating bacterial killing as well as the resolution of local inflammation. In community-acquired pneumonia, this may account for the therapeutic benefit of macrolides, even when bacterial eradication is not complete. A variety of effects of macrolides on Pseudomonas aeruginosa, including the inhibition of biofilm matrix, contribute with immunomodulation to the improvement of respiratory function seen with macrolides in cystic fibrosis.

SUMMARY

Macrolides can facilitate the killing of microorganisms in acute respiratory infections through the stimulation of neutrophil activation. On long-term administration, anti-inflammatory, T helper type 1 lymphocyte-enhancing and biofilm-thinning actions, among others, make macrolides valid therapeutic options in chronic infectious/inflammatory disorders, even for infections with microorganisms that are not completely eradicated.

Telithromycin treatment of chronic Chlamydia pneumoniae infection in C57BL/6J mice

Chronic Chlamydia pneumoniae infections have been associated with atherosclerosis, but clear knowledge about how these infections should be treated is lacking. We studied the effect of a new ketolide antibiotic, telithromycin, on chronic C. pneumoniae lung infection. Female C57BL/6J mice on a 0.2% cholesterol diet were inoculated intranasally with C. pneumoniae either two or three times every fourth week. Telithromycin was given to the mice subcutaneously at 75 mg/kg of body weight once daily for 5 or 10 days, starting at 3 days after the last inoculation. Samples were taken at 4 and 12 weeks after the last inoculation. The presence of C. pneumoniae DNA in lung tissue was demonstrated by PCR and the detection of lipid accumulation in the aortic sinus by Oil-Red-O staining. C. pneumoniae DNA positivity and inflammatory reactions in the lung tissue of the mice inoculated twice were significantly affected by treatment after both inoculations or only after the second inoculation at 12 weeks. Intimal lipid accumulation in the aortic sinus was also slightly but significantly less abundant in the mice treated after both inoculations compared to the levels in those treated only after the second inoculation for 10 days (geometric means, 823 and 4,324 microm(2), respectively; P = 0.033). No differences between the infected, untreated controls and the group inoculated three times and treated for 5 days were seen. We conclude that telithromycin is effective in preventing the development of chronic C. pneumoniae infection and intimal lipid accumulation in C56BL/6J mice when the treatment is given after each inoculation.

Single-drug or combined antibacterial therapy in the treatment of patients with chronic prostatitis and Chlamydia trachomatis?

The efficacy of antibacterial combinations as compared with single-drug treatment in 57 patients with chronic prostatitis and Chlamydia trachomatis was investigated in this study.

Antibiotic treatment of atherosclerosis

PURPOSE OF REVIEW

Several lines of evidence have demonstrated an association between a variety of chronic bacterial infections and atherosclerotic cardiovascular disease. This has led to the proposal that antibiotic therapy might be helpful in the secondary prevention of atherosclerosis. A variety of smaller pilot studies have been reported testing this hypothesis and several large multicenter trials are also underway. The purpose of this review is to summarize the results of these studies and comment on their implications for the treatment of atherosclerosis.

RECENT FINDINGS

Most of the antibiotic studies to date have been secondary prevention studies that have targeted patients exposed to Chlamydia pneumoniae. Most have used either azithromycin or roxithromycin with treatment courses ranging from a few days to 3 months. Several small studies of coronary artery disease patients have shown significant promise for reducing cardiovascular events such as death, myocardial infarction, or admission for unstable angina. However, other studies have not been so positive. Weekly Intervention with Zithromax for Atherosclerosis and its Related Disorders, WIZARD, the largest study to date, in which stable post-myocardial infarction patients were randomized to receive a 3-month course of azithromycin or placebo, demonstrated a significant reduction in death and myocardial infarction by 6 months, but this benefit was not sustained throughout the remaining course of follow-up. The Azithromycin and Coronary Events (ACES) and Pravastatin or Atorvastatin Evaluation and Infection Therapy (PROVE-IT) trials are ongoing and are testing the effect of more prolonged treatment duration.

SUMMARY

A variety of antibiotic trials for the secondary prevention of atherosclerosis have been performed. Several pilot studies have shown significant positive clinical effects, but, thus far, no large randomized trial has confirmed those findings. Some concerns over the antibiotics chosen and the duration of treatment have been raised. Other trials are underway to address some of those concerns. In the meantime, no recommendation for the use of antibiotic therapy for the secondary prevention of atherosclerosis can yet be made.

Experimental models of pulmonary infection

Experimental models of pulmonary infection are being discussed, focused on various aspects of good experimental design, such as choice of animal species and infecting strain, and route of infection/inoculation techniques (intranasal inoculation, aerosol inoculation, and direct instillation into the lower respiratory tract). In addition, parameters to monitor pulmonary infection are being reviewed such as general clinical signs, pulmonary-associated signs, complication of the pulmonary infection, mortality rate, and parameters after dissection of animals. Examples of pulmonary infection models caused by bacteria, fungi, viruses or parasites in experimental animals with intact or impaired host defense mechanisms are shortly summarized including key-references.

The intracellular life of chlamydiae

The ability to cause persistent infection is one of the major characteristics of all chlamydial species in their appropriate hosts. Persistent infection with Chlamydia trachomatis and Chlamydia pneumoniae has been implicated in the pathogenesis of many chronic diseases, some initially not thought to be infectious, including pelvic inflammatory disease, arthritis, asthma, and atherosclerosis. Chlamydiae have a unique developmental cycle with morphologically distinct infectious and reproductive forms: elementary (EB) and reticulate bodies (RB). Chlamydiae appear to circumvent the host endocytic pathway and inhabit a nonacidic vacuole that is dissociated from late endosomes and lysosomes. Chlamydiae also have been demonstrated to enter a persistent state after treatment with cytokines such as interferon-gamma (IFN-gamma), treatment with antibiotics, or restriction of certain nutrients, or to enter this state spontaneously under certain culture conditions. While the organism is in the persistent state, metabolic activity is reduced, and the organism is often refractory to antibiotic treatment. Ultrastructural analysis of IFN-gamma-treated C pneumoniae demonstrates atypical inclusions containing large reticulate-like aberrant bodies with no evidence of redifferentiation into EBs. Persistent C pneumoniae infection appears to be associated with continued expression of genes associated with DNA replication but not with those genes involved with bacterial cell division. The latter observation may explain the appearance of the large abnormal RBs seen in ultrastructural studies. Studies of the association of chlamydiae with chronic disease have been hampered by difficulties in diagnosing chronic, persistent infection with the organism, which, in turn, render determining the efficacy of antibiotic therapy very difficult.

Antibiotic use and risk of ischemic stroke in the elderly

PURPOSE

To determine whether treating infections with antibiotics that have antichlamydial activity decreases the risk of ischemic stroke in the elderly.

SUBJECTS

We analyzed data from 199 553 subjects 65 years and older in a health care claims database who had continuous health and pharmacy coverage for at least 2 years between January 1, 1991, and September 30, 1997. Using proportional hazards models with time-dependent covariates for prior antibiotic prescription and adjusting for cardiovascular risk factors, we determined the associations between antibiotic use and first claim for ischemic stroke (n = 7,335) during the observation period.

RESULTS

Rates of stroke (per 1,000 person-years) were 6.64 for macrolides, 9.27 for quinolones, 7.49 for tetracyclines, 6.88 for penicillins, 7.97 for cephalosporins, 8.58 for trimethoprim-sulfamethoxazole, and 7.29 for subjects with no antibiotic claims. The adjusted hazard ratios (HR) were 0.94 (95% confidence interval [CI]: 0.87 to 1.01) for macrolides, 1.04 (95% CI: 0.91 to 1.18) for tetracyclines, 1.02 (95% CI: 0.95 to 1.08) for penicillins, and 1.00 (95% CI: 0.82 to 1.22) for trimethoprim-sulfamethoxazole. Subjects with claims for quinolone antibiotics (HR = 1.17; 95% CI: 1.09 to 1.26) and cephalosporins (HR = 1.09; 95% CI: 1.02 to 1.16) had a slightly higher risk of stroke.

CONCLUSION

Exposures to short courses of antibiotics are not associated with lower risk of ischemic stroke in patients aged 65 years and older.