Double-blind, placebo-controlled study comparing the effect of azithromycin with clarithromycin on oropharyngeal and bowel microflora in volunteers

A scoping review of African natural products against gastric ulcers and Helicobacter pylori

ETHNOPHARMACOLOGICAL RELEVANCE

African traditional medicine is one of the oldest and most diverse practices for treating ailments and numerous natural products have been recommended for gastric ulcer treatment. Helicobacter pylori is the main causative organism implicated in several diseases, most notably in causing inflammation and the onset of gastric ulcers. Current H. pylori treatment methods are losing efficacy as H. pylori rapidly gains resistance to antibiotics. Hence, a search into natural products and their historical traditional efficacy for the treatment of gastric ulcers is of interest.

AIM OF THE STUDY

This review aimed to summarise the African use of natural products, including medicinal plants noted in ethnobotanical reviews, used traditionally to treat gastric ulcers, and highlights the investigations into the anti-H. pylori activity of medicinal plants and bee products found in Africa.

METHODOLOGY

A systematic review was carried out to identify natural products, including those used traditionally in Africa to treat gastric ulcers, and to correlate this with scientific investigations into the anti-H. pylori activity of natural products used in Africa.

RESULTS

A total of 107 literature sources describing the traditional use of medicinal plants in gastric ulcer treatment were found, from which 360 medicinal plants were identified. Of the plants used traditionally for gastric ulcer treatment, 11% were investigated either in vitro or in vivo for anti-ulcer and anti-H. pylori activity. Of the 122 medicinal plants eliciting antimicrobial or anti-ulcer activity, Hibiscus sabdariffa L. calyx extract and Terminalia macroptera Guill. & Perr. root extract were found to have the most noteworthy antimicrobial activity, with minimum inhibitory concentrations (MICs) of 0.01 mg/mL and 0.03 mg/mL respectively. The essential oils of Piper longum L. and Pachira aquatica Aubl. displayed the most notable in vitro anti-H. pylori activity (MIC of 0.01 mg/mL and 0.02 mg/mL). Several in vivo studies found medicinal plant extracts effective in reducing the H. pylori load along the gastric mucosa. The South African honey variants, Pure Honey and Champagne Royal Train (common names given by supplier) were the most antimicrobially effective (MIC of 0.01-10.0%, 0.63-10.00% v/v) in inhibiting H. pylori when assessed in vitro.

CONCLUSION

These results highlight the potential of natural products to inhibit H. pylori growth and serve as a possible stepping-stone in understanding the management of ulcers. Furthermore, effective natural product treatment or prophylactic use for preventing H. pylori growth may provide a more affordable option for African populations.

Antibiotic-induced changes in the human gut microbiota for the most commonly prescribed antibiotics in primary care in the UK: a systematic review

OBJECTIVE

The gut microbiota influences many aspects of human health. We investigated the magnitude and duration of changes in gut microbiota in response to antibiotics commonly prescribed in UK primary care.

METHODS

We searched MEDLINE, EMBASE and AMED, all years up to May 2020 including all study designs, collecting and analysing data on the effect of antibiotics prescribed for respiratory and urinary tract infections. We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses and Cochrane standard methods. Risk of bias was evaluated using the Critical Appraisal Skills Programme. Narrative synthesis was used to report the themes emerging from the data.

MAIN OUTCOME MEASURES

Primary outcomes were antibiotic-induced changes in the composition and/or diversity of the gut microbiota. Secondary outcome was the time for the microbiota to return to baseline.

RESULTS

Thirty-one articles with low or unclear risk of bias showed that antibiotics impact the gut microbiota by causing rapid and diminished levels of bacterial diversity and changes in relative abundances. After cessation of treatment, gut bacteria recover, in most individuals, to their baseline state within a few weeks. Some studies suggested longer term effects from 2 to 6 months. Considerable heterogeneity in methodology makes the studies prone to biases and other confounding factors. Doxycycline was associated with a marked short-term decrease in Bifidobacterium diversity. Clarithromycin decreased the populations of Enterobacteria, and the anaerobic bacteria Bifidobacterium sp and Lactobacillus sp in numbers and diversity for up to 5 weeks. Phenoxymethylpenicillin, nitrofurantoin and amoxicillin had very little effect on the gut microbiome.

CONCLUSIONS

Despite substantial heterogeneity of the studies and small sample sizes, there is evidence that antibiotics commonly used in primary care influence the composition of the gastrointestinal microbiota. Larger population-based studies are needed to fully understand how antibiotics modulate the microbiota, and to determine if these are associated with (longer term) health consequences.

PROSPERO REGISTRATION NUMBER

CRD42017073750.

Chloroquine-azithromycin combination antimalarial treatment decreases risk of respiratory- and gastrointestinal-tract infections in Malawian children

BACKGROUND

Chloroquine-azithromycin is being evaluated as combination therapy for malaria. It may provide added benefit in treating or preventing bacterial infections that occur in children with malaria.

OBJECTIVE

We aim to evaluate the effect of treating clinical malaria with chloroquine-azithromycin on the incidence of respiratory-tract and gastrointestinal-tract infections compared to treatment with chloroquine monotherapy.

METHODS

We compared the incidence density and time to first events of respiratory-tract and gastrointestinal-tract infections among children assigned to receive chloroquine-azithromycin or chloroquine for all symptomatic malaria episodes over the course of 1 year in a randomized longitudinal trial in Blantyre, Malawi.

RESULTS

The incidence density ratios of total respiratory-tract infections and gastrointestinal-tract infections comparing chloroquine-azithromycin to chloroquine monotherapy were 0.67 (95% confidence interval [CI], .48, .94) and 0.74 (95% CI, .55, .99), respectively. The time to first lower-respiratory-tract and gastrointestinal-tract infections were significantly longer in the chloroquine-azithromycin arm compared to the chloroquine arm (P = .04 and P = .02, respectively).

CONCLUSIONS

Children treated routinely with chloroquine-azithromycin had fewer respiratory and gastrointestinal-tract infections than those treated with chloroquine alone. This antimalarial combination has the potential to reduce the burden of bacterial infections among children in malaria-endemic countries.

Macrolides vs. quinolones for community-acquired pneumonia: meta-analysis of randomized controlled trials

The relative efficacy, safety and ecological implications of macrolides vs. quinolones in the treatment of community-acquired pneumonia (CAP) are debatable. We performed a systematic review and meta-analysis of randomized controlled trials comparing any macrolide vs. any quinolone for the treatment of CAP among adult inpatients or outpatients, as monotherapy or both in combination with a beta-lactam. We did not limit inclusion by pneumonia severity, publication status, language or date of publication. The primary outcomes assessed were 30-day all-cause mortality and treatment failure. Two authors independently extracted the data. Fixed effect meta-analysis of risk ratios (RRs) with 95% confidence intervals was performed. Sixteen trials (4989 patients) fulfilling inclusion criteria were identified, mostly assessing outpatients with mild to moderate CAP. All-cause mortality was not significantly different for macrolides vs. quinolones, RR 1.03 (0.63-1.68, seven trials), with a low event rate (2%). Treatment failure was significantly lower with quinolones, RR 0.78 (0.67-0.91, 16 trials). The definition of failure used in the primary studies was not clearly representative of patients' benefit. Microbiological failure was lower with quinolones, RR 0.63 (0.49-0.81, 13 trials). All adverse events, adverse events requiring discontinuation and any premature antibiotic discontinuation were significantly more frequent with macrolides, mainly on account of gastrointestinal adverse events. Resistance development was not assessed in the trials. Randomized controlled trials show an advantage of quinolones in the treatment of CAP with regard to clinical cure without need for antibiotic modification at end of treatment and gastrointestinal adverse events. The clinical significance of this advantage is unclear.

Effect of azithromycin on acute inflammatory lesions and colonic bacterial load in a murine model of experimental colitis

BACKGROUND

The aim of this study was to investigate the effect of the macrolide antibiotic azithromycin on mucosal changes and colonic bacterial load in a murine model of colitis.

METHODS

Colitis was induced in CD1 mice using enema of 0.2% solution of dinitrofluorobenzene, combined with skin sensitization. Four experimental groups of animals (N = 10 per group) were treated with 50 mg/kg/day azithromycin (AZ) or metronidazole (MN) perorally, starting 24 h before (AZ-1, MN-1) or 6 h after (AZ+1, MN+1) induction of colitis and for consecutive 5 days. Additional experimental mice group was treated with 10 mg/kg/day methylprednisolone intraperitoneally after induction of experimental colitis in the same manner (MP). Two control groups consisted of healthy animals (C) that received the challenge enema with phosphate-buffered saline (PBS) and animals with experimental colitis (chall) treated with equivolume of PBS perorally. Clinical score (0-5) and histopathologic score (0-30) were used to assess inflammatory changes, and colon washings were used to determine changes in bacterial load.

RESULTS

The anti-inflammatory effect of azithromycin did not differ from the effect of methylprednisolone, when compared with control group with experimental colitis. Metronidazole did not show a significant anti-inflammatory effect. Number of colonic bacteria did not differ significantly between control and experimental groups of animals.

CONCLUSIONS

We documented the anti-inflammatory effect of azithromycin in a murine model of acute colitis, suggesting that effects were targeted to oxidative burst and on mucosal/bacterial interface, independent of luminal bacterial load. Further studies should be focused on effect of azithromycin on the role of bacterial biofilm in perpetuation of chronic intestinal inflammation.

Macrolide resistance in the normal microbiota after Helicobacter pylori treatment

Large-scale chemoprevention of peptic ulcer disease and gastric cancer through eradication of Helicobacter pylori would expose large population groups to antibiotics, which raises concerns about possible dissemination of antibiotic resistance. The objective of this cohort study was to determine whether a triple therapy, containing omeprazole, clarithromycin, and metronidazole, of H. pylori infection increases the prevalence of macrolide resistance in the normal microbiota. 85 patients with a peptic ulcer disease with verified H. pylori infection and 12 dyspeptic patients without positive findings upon endoscopy were included. Minimal inhibitory concentrations of clarithromycin for Staphylococcus, Streptococcus, Enterococcus and Bacteroides spp. were determined from samples taken before and after treatment, and 1 y later. Before treatment, macrolide resistance was observed in 11%, 31%, 9% and 11% of the staphylococci, streptococci, enterococci and Bacteroides, respectively. The number of resistant isolates remained elevated after 1 y, most notably for staphylococci and streptococci. No development of persistent resistance was detected in the untreated control group. Triple therapy including clarithromycin leads to persistent macrolide resistance in the normal microbiota. A prevalent pool of resistance genes in the normal microbiota constitutes an ecological hazard that needs to be considered before global treatment programmes for eradication of H. pylori are implemented.

Azithromycin extended release: a review of its use in the treatment of acute bacterial sinusitis and community-acquired pneumonia in the US

Azithromycin is a macrolide antibacterial agent. The novel microspheres oral extended-release formulation (Zmax) is the first antibacterial drug approved in the US for administration as a single dose in adult patients with mild to moderate acute bacterial sinusitis (ABS) or community-acquired pneumonia (CAP). It has a broad spectrum of in vitro antibacterial activity against Gram-positive, Gram-negative and atypical pathogens that cause ABS and CAP infections (including Streptococcus pneumoniae), and achieves good tissue penetration. Azithromycin extended release is an effective and generally well tolerated treatment in patients with ABS or CAP. The clinical cure rates of a single 2.0 g dose of azithromycin extended release were noninferior to those obtained with a 10-day regimen of levofloxacin in patients with ABS, and with 7-day regimens of clarithromycin extended release or levofloxacin in patients with CAP. With a pharmacodynamic and pharmacokinetic profile well suited to administration as a single-dose regimen that may offer the advantage of improved compliance and convenience compared with once-daily longer-course regimens, azithromycin extended release is a new option in the empirical treatment of adult patients with mild or moderate ABS or CAP in the US.

Effect of azithromycin and clarithromycin therapy on pharyngeal carriage of macrolide-resistant streptococci in healthy volunteers: a randomised, double-blind, placebo-controlled study

BACKGROUND

Resistance to antibiotics is a major public-health problem, and studies that link antibiotic use and resistance have shown an association but not a causal effect. We used the macrolides azithromycin and clarithromycin to investigate the direct effect of antibiotic exposure on resistance in the oral streptococcal flora of healthy volunteers.

METHODS

Volunteers were treated with azithromycin (n=74), clarithromycin (74), or placebo (76) in a randomised, double-blind trial. Pharyngeal swabs were obtained before and after administration of study treatment through 180 days. The proportion of streptococci that were macrolide resistant was assessed and the molecular basis of any change in resistance investigated. Analyses were done on an intent-to-treat basis. This study is registered with ClinicalTrials.gov, number NCT00354952.

FINDINGS

The number of dropouts (n=20) was much the same in all groups until day 42; dropouts increased substantially at day 180 (105). Both macrolides significantly increased the proportion of macrolide-resistant streptococci compared with the placebo at all points studied, peaking at day 8 in the clarithromycin group (mean increase 50.0%, 95% CI 41.7-58.2; p<0.0001) and at day 4 in the azithromycin group (53.4%, 43.4-63.5; p<0.0001). The proportion of macrolide-resistant streptococci was higher after azithromycin treatment than after clarithromycin use, with the largest difference between the two groups at day 28 (17.4% difference, 9.2-25.6; p<0.0001). Use of clarithromycin, but not of azithromycin, selected for the erm(B) gene, which confers high-level macrolide resistance.

INTERPRETATION

This study shows that, notwithstanding the different outcomes of resistance selection, macrolide use is the single most important driver of the emergence of macrolide resistance in vivo. Physicians prescribing antibiotics should take into account the striking ecological side-effects of such antibiotics.

Comparative effects of single-dose ceftriaxone versus three oral antibiotic regimens on stool colonization by resistant bacilli in children

OBJECTIVE

The use of short-term intramuscular ceftriaxone for pediatric ambulatory conditions raises concerns regarding the promotion of resistance among colonizing enteric bacteria. This study was designed to assess the prevalence of stool colonization with resistant Gram-negative bacilli after single-dose ceftriaxone treatment compared with other regimens for acute otitis media.

METHODS

Children age 3 months to 7 years and diagnosed with acute otitis media were randomized to receive treatment with single-dose ceftriaxone or with oral cefprozil, amoxicillin or azithromycin. Stool samples were obtained at enrollment and then 3-5 days, 10-14 days, and 28-30 days after therapy was initiated and screened for the presence of facultative Gram-negative bacilli resistant to ceftriaxone, cefprozil, amoxicillin, piperacillin, piperacillin-tazobactam and tobramycin. Mean prevalence of colonization by resistant organisms for each treatment group was compared at each time point.

RESULTS

One thousand nine subjects were enrolled. The prevalence of colonization by a Gram-negative bacillus resistant to at least 1 of the screening antibiotics decreased after receipt of ceftriaxone but returned close to values measured at study entry by 30 days. A qualitatively similar pattern was noted for the 3 other regimens, but a quantitatively greater decrease in the prevalence of colonization by a resistant bacterium was noted at the 3- to 5-day and 10- to 14-day visits among azithromycin recipients (P < 0.001). Colonization by a Gram-negative bacillus resistant specifically to ceftriaxone was unusual at each study visit, regardless of treatment assignment.

CONCLUSIONS

A single intramuscular dose of ceftriaxone had a similar effect on the prevalence of antibiotic-resistant Gram-negative facultative bacilli in the stool of healthy children when compared with commonly used oral agents.

Effects of anti-Helicobacter pylori treatment and probiotic supplementation on intestinal microbiota

The aims of this study were (i) to evaluate the effect of recommended antimicrobial treatment of Helicobacter pylori infection, consisting of clarithromycin, amoxicillin and lansoprazole, on intestinal microbiota and (ii) to determine the ability of a probiotic combination containing Lactobacillus rhamnosus GG, L. rhamnosus LC705, Propionibacterium freudenreichii ssp. shermanii JS and Bifidobacterium breve Bb99 to prevent treatment-induced alterations in the intestinal microbiota. Faecal samples were obtained from 39 H. pylori-infected patients randomised into two treatment groups. In addition, 19 H. pylori-negative volunteers were included in the study as a control group. Samples were collected before, during and after treatment and microbiota were analysed by fluorescence in situ hybridisation and culture. The quantities of the predominant bacterial groups were altered significantly in both groups and disturbances were seen even 9 weeks after treatment was complete. Probiotics slightly counteracted the effects of anti-H. pylori treatment, seen as significantly less alterations in the total numbers of aerobes and lactobacilli/enterococci. At baseline, the composition of the microbiota between H. pylori-positive versus H. pylori-negative control individuals differed with regard to clostridia and the total number of anaerobes. The recommended treatment for H. pylori infection induces long-term disturbances in the intestinal microbiota. The probiotic combination appeared to result in only minor changes in the microbiota.

Erythromycin resistance in the commensal throat flora of patients visiting the general practitioner: a reservoir for resistance genes for potential pathogenic bacteria

The prevalence and mechanism of erythromycin resistance in commensal throat streptococci was determined from October 2000 until December 2002 as part of an ongoing study of the NIVEL in general practice patients (N=678). Resistance prevalence for 1mg/L and 16 mg/L erythromycin was 57% and 20%, respectively. The percentage of total commensal flora resistant within each patient ranged from 1% to 100% (median, 1%). mefA was predominantly found among isolates on the 1mg/L plates, and ermB was found in 64% of the isolates on the 16 mg/L plates. Erythromycin resistance was transferred from a commensal isolate to Streptococcus pneumoniae with a frequency of 1 x 10(-9). Commensal streptococci of general practice patients in The Netherlands form a large reservoir of transferable erythromycin resistance (genes) for potential pathogenic microorganisms.

Two Regimens of Azithromycin Prophylaxis against Community‐Acquired Respiratory and Skin/Soft‐Tissue Infections among Military Trainees

Epidemics of community-acquired pneumonia (CAP) are a frequent cause of morbidity among Russian military trainees. We evaluated azithromycin prophylaxis against CAP. In 2001-2002, incoming military trainees were randomized to 1 of 3 trial arms by training group: azithromycin, 500 mg per week for 8 weeks (R1); azithromycin, 1500 mg once at enrollment (R2); or no therapy (R3). During the 22 weeks of training, CAP was diagnosed in 20.2% of 678 subjects in the R3 group, 8.6% of 508 subjects in the R1 group, and 10.3% of 507 subjects in the R2 group. Throat carriage cultures revealed that the proportion of Streptococcus pneumoniae isolates with resistance to macrolides correspondingly increased during the study, from 0% (all) to 40% (R1) and 22.6% (R2) by week 20. Azithromycin prophylaxis is effective against CAP in a healthy population of young men at transient high risk of disease; however, azithromycin use must be tempered with the possible concomitant risk of selection for resistant endemic pathogens.