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Background: In 2019, a new type of coronavirus emerged and spread to the rest of the world. Numerous drugs were identified as possible treatments. Among the candidates for possible treatment was azithromycin alone or in combination with other drugs. As a result, many clinicians in Brazil have prescribed azithromycin in an attempt to combat or minimize the effects of COVID19. Aim: This study analyzed the sales data of the main antibiotics prescribed in Brazil to verify the change in consumption trends of these drugs during the COVID-19 pandemic. Methods: This is an interrupted time series that analyzed antimicrobial sales data between January 2014 and July 2021, publicly accessible information obtained from the Brazilian government's website. Monthly means of "defined daily doses of DDDs" (DDDs per 1,000 inhabitants per day) of antibiotics were compared by analysis of variance, followed by the Dunnett Multiple Comparisons Test. Monthly trend changes in antibiotic use were verified using Joinpoint regression. Results: Amoxicillin (31.97%), azithromycin (18.33%), and cefalexin (16.61%) were the most sold antibiotics in Brazil during the evaluation period. Azithromycin consumption rose from 1.40 DDDs in February 2020 to 3.53 DDDs in July 2020. Azithromycin sales showed a significant increase in the pandemic period [Monthly Percent Change (MPC) 5.83%, 95% 1.80; 10.00], whereas there was a fall in amoxicillin sales (MPC −9.00%, 95% CI −14.70; −2.90) and cefalexin [MPC-2.70%, 95% (CI −6.30; −1.10)] in this same period. Conclusion: The COVID-19 pandemic changed the pattern of antibiotic consumption in Brazil, with a decrease in the use of amoxicillin and cefalexin and an increase in the consumption of azithromycin. [ABSTRACT FROM AUTHOR]

ABSTRACT: Sporotrichosis is an infection caused by a dimorphic fungus. Typically transmitted through inoculation of contaminated foliage, this disease is seen primarily in farmers or garden workers. The initial manifestation is a single papule at the sight of trauma. The differential diagnosis includes diseases with localized eruptions and lymphangitic spread. Cases caused by zoonotic transmission through felines have also been rising in Brazil. We report this case of a woman who contracted sporotrichosis via cat scratches. [ABSTRACT FROM AUTHOR]

The Second and Third Brazilian Consensuses on Helicobacter pylori indicate the combination of a proton pump inhibitor (PPI), amoxicillin, and clarithromycin as the first-line therapy for eradicating this pathogen, but this regimen has been criticized for the recent decrease in its efficacy in several parts of the world. There are little data on the efficacy of H. pylori eradication regimens in the interior of Brazil. OBJECTIVE: To describe the treatments prescribed for the eradication of H. pylori with their respective efficacy rates in a cohort living in the Zona da Mata of Minas Gerais. DESIGN: A retrospective cohort study with treatment-naïve patients known to have gastric infection by H. pylori, residents of the Zona da Mata of Minas Gerais, submitted to eradication therapy of this pathogen in the periods 2007 to 2011, and 2013 to 2016. The H. pylori eradication rates obtained with the prescribed treatments were evaluated as outcomes. RESULTS: We analyzed 5010 medical records from a single health service, with 264 prescriptions for initial treatments to eradicate H. pylori using PPI associated with amoxicillin and clarithromycin for 7 days in 243 cases (88.25%). The overall efficacy rate of this regimen was 54.07%, with no differences in efficacy between the two periods analyzed (2007 to 2011: 54.55%, 2013 to 2016: 53.65, p = 0.892) There were no differences in efficacy according to the choice of PPI: Omeprazole-AC7: 52.55%, OR = 1 (72 successes out of 137); Lansoprazole-AC7: 44.18%. OR = 1.399, p = 0.28 (38 out of 86); and Pantoprazole-AC-7: 60%, OR = 0.739, p = 0.701 (12 out of 20). CONCLUSIONS: In this cohort, the efficacy rates of the regimens recommended by the Brazilian Consensus on Helicobacter pylori were lower than those previously described in the Brazilian literature, suggesting the need for a revision of the official recommendations. [ABSTRACT FROM AUTHOR]

Amoxicillin is an antibiotic that can accumulate in aquatic environments and lead to the development of resistant bacteria; thus, its determination is of great importance. In this study, a glassy carbon electrode modified with reduced graphene oxide and Nafion was used as a sensor in a square-wave voltammetry method for determination of amoxicillin in river water samples from Guarapuava city, Brazil. The method was validated, using parameters and statistical tools recommended by the validation guidelines, in the range of 1.8–5.4 μmol L−1 (r = 0.922 and R2 = 85.1%). The analytical curve was constructed using external standard calibration in pure electrolyte, since the matrix effect was not significant. Results of linear regression analysis, lack of fit test and analysis of the residual plots pointed that the linear regression was significant, without lack of fit of linear model and that the variances had homoscedastic distribution. Both coefficients of regression curve were significant and, thus, they were included in the regression equation: Response = 7.0 + 3.5C AMX. The limits of detection and quantification were 0.36 and 1.2 μmol L−1, respectively. The method was selective towards interferents such as humic acids and benzylpenicillin. The relative standard deviations for repeatability and intermediate precision were adequate according to the limits established in literature. The mean recoveries were statistically equal to those obtained through a comparative chromatography method, so, the accuracy of the method was also adequate. Therefore, the method can be applied to the voltammetric determination of amoxicillin in river water, affording reliable and consistent measurements. Image 1 • A glassy carbon electrode modified with rGO and Nafion sensor was constructed. • A SWV method for determination of AMX was developed and validated. • The parameters of validation were adequate, according to the literature. • The method was applied in the determination of AMX in river water. [ABSTRACT FROM AUTHOR]

Abstract Ethnopharmacological relevance Northeast Brazilian ethnoveterinary studies associated with the medicinal use of zootherapies have shown that ruminants' body fat such as sheep (Ovis aries), goats (Capra hircus) and cows (Bos taurus) are used in diseases affecting domestic animals. Aim of the study The objective of this study was to evaluate the antibacterial activity of the fixed oils from these ruminants in isolation and in association with antibiotics. Results Ovis aries (OFOA), Capra hircus (OFCH) and Bos taurus (OFBT) fixed oils were extracted using a Soxhlet apparatus with hexane as the solvent. Through the use of gas chromatography coupled to mass spectrometry (GC-MS) the methyl esters from the ruminants' fixed oils were obtained and the fatty acids present in these oils were indirectly determined. The OFOA, OFCH and OFBT antibacterial and antibiotic modifying activities against standard and multi-resistant bacterial strains were carried out using the broth microdilution test. The fixed oils from these species did not present antibacterial activity when tested in isolation, obtaining Minimal Inhibitory Concentration (MICs) values ≥ 1024 μg/mL. However, when associated with antibiotics, OFBT and OFCH showed a synergistic activity for the Amicacin, Amoxicillin, Norfloxacin and Oxytetracycline antibiotics. Conclusion The OFOA promoted a synergistic action for the same antibiotics with the exception of Norfloxacin. [ABSTRACT FROM AUTHOR]

Objective: The aim of this randomized double‐blind and placebo‐controlled study was to assess if periodontal treatment with or without systemic antibiotic would change the mean level of Archaea. Methods: Fifty‐nine (59) subjects were randomly assigned to receive scaling and root planing (SRP) alone or combined with metronidazole (MTZ; 400 mg/TID) or either with MTZ and amoxicillin (AMX; 500 mg/TID) for 14 days. Clinical and microbiological examinations were performed at baseline and at 6 months post‐SRP. Six subgingival plaque samples per subject were analysed for the presence and levels of Archaea using quantitative polymerase chain reaction. Results: Scaling and root planing alone or combined with MTZ or MTZ + AMX significantly reduced the prevalence of subjects colonized by Archaea at 6 months post‐therapy, without significant differences among groups (P > .05). Both therapies led to a statistically significant decrease in the mean percentage of sites colonized by Archaea (P < .05). The MTZ and MTZ + AMX group had a significantly lower mean number of sites colonized by Archaea and lower levels of these micro‐organisms at sites with probing depth ≥5 mm at 6 months compared with SRP group (P < .05). Conclusion: Periodontal treatments including adjunctive MTZ or MTZ + AMX are more effective than mechanical treatment alone in reducing the levels and prevalence of sites colonized by Archaea in subjects with chronic periodontitis. [ABSTRACT FROM AUTHOR]

The COVID-19 brought a new model of sanitary behavior (social distancing, etc.) that may have reduced the transmissibility of respiratory diseases, reflecting in the number of antibiotic prescriptions. This study evaluated antibiotic prescriptions for children throughout Brazil, between 2014 and 2021. An interrupted time series was conducted to assess variations in antibiotic consumption by the 1-12-year-old children. Joinpoint regression was used to assess the monthly variations. 86 million prescriptions were evaluated. On average, there was a 54% reduction in prescriptions during the pandemic. Amoxicillin showed a reduction of 65%. Joinpoint regression showed that the pandemic altered the prescription growth curve, changing the trend to a 22% drop per month. The new sanitary behavior showed us that it is possible, decreasing the use of antibiotics, to control the children's respiratory health., (© 2022. The Author(s).)

Aim To evaluate the clinical and microbiological effects of the use of metronidazole ( MTZ) + amoxicillin ( AMX) as adjuncts to scaling and root planing ( SRP) for the treatment of chronic periodontitis (ChP) in type 2 diabetic subjects. Material and Methods Fifty-eight type 2 diabetic subjects ( n = 29/group) with generalized ChP were randomly assigned to receive SRP alone or with MTZ [400 mg/thrice a day (TID)]+AMX (500 mg/TID) for 14 days. Subgingival biofilm samples were analyzed by qPCR for the presence of seven periodontal pathogens. Subjects were monitored at baseline, 3, 6 and 12 months post-therapies. Results The group receiving SRP+ MTZ+ AMX presented greater mean probing depth ( PD) reduction and clinical attachment gain, a lower number of sites with PD ≥5 mm (primary outcome variable) and a reduced number of subjects with ≥9 of these residual pockets than the control group at 1-year post-therapy ( p < 0.05). The antibiotic-treated group also presented reduced levels and greater decreases of the three red complex species, Eubacterium nodatum and Prevotella intermedia, compared to the control group at 1 year ( p < 0.05). Conclusions The adjunctive use of MTZ+ AMX significantly improved the clinical and microbiological outcomes of SRP in the treatment of type 2 diabetic subjects with ChP. [ABSTRACT FROM AUTHOR]

Aim To evaluate the changes occurring in the subgingival microbial profile of subjects with generalized chronic periodontitis (ChP) treated by scaling and root planing ( SRP) alone or with metronidazole ( MTZ) or MTZ + amoxicillin ( AMX). A secondary aim was to examine a possible added effect of chlorhexidine ( CHX) to these therapies. Methods One hundred and eighteen subjects were randomly assigned to receive SRP-only or with MTZ [400 mg/thrice a day ( TID)] or MTZ + AMX (500 mg/ TID) for 14 days. Half of the subjects in each group rinsed with 0.12% CHX twice a day ( BID) for 2 months. Nine subgingival plaque samples/subject were analysed by checkerboard DNA- DNA hybridization for 40 bacterial species at baseline, 3, 6 and 12 months post-therapy. Results At 12 months, the antibiotic-treated groups harboured lower mean counts and proportions of key periodontal pathogens than the SRP group ( p < 0.05). These benefits were observed at initially deep and shallow sites. Initial reductions in periodontal pathogens obtained with SRP partially rebound after 12 months. CHX rinsing enhanced the microbiological effects of the MTZ + AMX treatment in shallow sites. Conclusion The adjunctive use of MTZ and MTZ + AMX results in a greater reduction in the levels of periodontal pathogens in generalized ChP subjects compared to SRP alone. [ABSTRACT FROM AUTHOR]

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Francisellosis is an emerging disease caused by Francisella orientalis and is responsible for major economic losses in tilapia farms worldwide. The method of choice for francisellosis outbreak control is oral antibiotic administration, as no commercial vaccines or autogenous effective vaccines are available. Although there is a standard method recommended by the Clinical and Laboratory Standards Institute (CLSI) for susceptibility testing of fish pathogenic Francisella spp., basic information on culture and growth conditions for this pathogen is scarce. In this study, the antibiotic susceptibility profile of Francisella orientalis was determined using the disk diffusion test. For that, 89 Francisella orientalis samples obtained from disease outbreaks in tilapia farms in 2012–2019 in various Brazilian states were selected for testing against different antibiotics. Because F. orientalis cannot grow on the standard Mueller-Hinton (MH) agar medium, two different culture media were selected for testing: modified heart cystine agar (CHAH) and modified cation-adjusted Mueller-Hinton agar (MMHA). Different incubation periods were also tested for more appropriate and accurate measurement data. CHAH was more suitable for performing the diffusion disk tests because MMHA required longer incubation periods and formed overestimated inhibition zones. Incubation time affected the antibiogram results mainly for β-lactam antibiotics, with 48 h being the ideal period for measuring inhibition zones. Epidemiological cutoff values of Francisella orientalis isolates using the normalized resistance interpretation (NRI) methodology were successfully calculated. All 89 isolates (100%) were considered wild type (WT) for florfenicol, oxytetracycline, erythromycin, and doxycycline, whereas 86 isolates (96.6%) were considered WT for amoxicillin, ampicillin, enrofloxacin, and norfloxacin. Three isolates (3.4%) were considered non-wild type (NWT) for enrofloxacin, norfloxacin, amoxicillin, and ampicillin. This is the first report of Francisella orientalis isolates resistant to amoxicillin and fluoroquinolones. This study provided important data on Francisella orientalis antibiotic susceptibility. Moreover, it showed that Brazil is already suffering the effects of the inadvertent use of licensed drugs and of off-label drugs, as the aforementioned drug classes are illegally used for farmed fish in the country. • The modified heart cystine agar (CHAH) medium and 48-h incubation were suitable for diffusion disk testing of Francisella orientalis. • Epidemiological cutoff values were determined using normalized resistance interpretation (NRI) for eight antibiotics. • All isolates were wild type (WT) for florfenicol, oxytetracycline, erythromycin, and doxycycline. • Francisella orientalis resistant to norfloxacin and enrofloxacin is herein firstly described. [ABSTRACT FROM AUTHOR]

Aim To evaluate the effects of the adjunctive use of metronidazole ( MTZ) or MTZ + amoxicillin ( AMX) in the treatment of generalized chronic periodontitis (ChP). A secondary aim was to examine a possible added effect of chlorhexidine to these therapies. Methods One hundred and eighteen subjects received scaling and root planing ( SRP) only or with MTZ [400 mg/thrice a day ( TID)] or MTZ+ AMX (500 mg/ TID) for 14 days. Half of the subjects in each group rinsed with 0.12% chlorhexidine twice a day (BID) for 2 months. Subjects were clinically monitored at baseline, 3, 6 and 12-months post-therapy. Results The two antibiotic groups showed lower mean number of sites with probing depth ( PD) ≥5 mm and fewer subjects exhibiting ≥9 of these sites at 1-year post-treatment. Logistic regression analysis showed that antibiotics were the only significant predictors of subjects presenting ≤4 sites with PD ≥5 mm at 1 year ( MTZ+ AMX: OR, 13.33; 95% CI, 3.75-47.39/ p = 0.0000; MTZ: OR, 7.26; 95% CI, 2.26-23.30/ p = 0.0004). The frequency of adverse events did not differ between the two antibiotic treatments ( p > 0.05). The chlorhexidine subgroups showed a trend ( p > 0.05) to present fewer residual sites ≥5 mm compared with the placebo subgroups at 1 year. Conclusion Treatment of generalized ChP is significantly improved by the adjunctive use of MTZ+ AMX and MTZ. [ABSTRACT FROM AUTHOR]

Aim To evaluate the clinical effects of the adjunctive use of metronidazole ( MTZ) and amoxicillin ( AMX) in the treatment of generalized aggressive periodontitis ( GAgP). Methods Thirty subjects were randomly assigned to receive scaling and root planing ( SRP) alone or combined with MTZ (400 mg/TID) and AMX (500 mg/TID) for 14 days. Subjects were clinically monitored at baseline, 6 months and 1 year post-therapies. Results Both therapies led to a statistically significant improvement in all clinical parameters at 1 year post-therapy ( p < 0.05). Subjects receiving MTZ plus AMX exhibited the deepest reductions in mean probing depth ( PD) and gain in clinical attachment between baseline and 1 year post-therapy in the full-mouth analysis and in initially intermediate ( PD 4-6 mm) and deep ( PD≥7 mm) sites ( p < 0.01). In addition, the antibiotic group presented lower mean number of residual sites with PD≥5 or 6 mm as well as fewer subjects still presenting nine or more sites with PD≥5 mm or three or more sites with PD≥6 mm at the end of the study period. Conclusion The non-surgical treatment of GAgP is markedly improved by the adjunctive use of MTZ+ AMX, up to 1 year post-treatment. [ABSTRACT FROM AUTHOR]

Silva MP, Feres M, Sirotto TAO, Soares GMS, Mendes JAV, Faveri M, Figueiredo LC. Clinical and microbiological benefits of metronidazole alone or with amoxicillin as adjuncts in the treatment of chronic periodontitis: a randomized placebo-controlled clinical trial. J Clin Periodontol 2011; 38: 828-837. doi: 10.1111/j.1600-051X.2011.01763.x. Abstract Aim: To evaluate the effects of the adjunctive use of metronidazole (MTZ) or MTZ+amoxicillin (AMX) in the treatment of generalized chronic periodontitis (ChP). Materials and methods: Fifty-one subjects ( n=17/group) were randomly assigned to receive scaling and root planing (SRP) only or combined with MTZ (400 mg t.i.d.) or MTZ+AMX (500 mg t.i.d.) for 14 days. Clinical and microbiological examinations were performed at baseline and 3 months post-SRP. Nine plaque samples/subject were analysed by checkerboard DNA-DNA hybridization for 40 bacterial species. Results: Subjects receiving MTZ+AMX exhibited a greater mean gain of clinical attachment, reduction in probing depth (PD) in intermediate and deep sites and a lower percentage of sites with PD5 mm at 3 months, in comparison with those treated with SRP only ( p<0.05). The major benefit from the adjunctive use of MTZ was a greater reduction in PD in deep sites. SRP+MTZ+AMX was the only treatment that significantly reduced the levels and proportions of all red complex pathogens and elicited a significantly greater beneficial change in the microbial profile in comparison with SRP only. Conclusion: The adjunctive use of MTZ+AMX offers short-term clinical and microbiological benefits, over SRP alone, in the treatment of non-smokers subjects with generalized ChP. The added benefits of MTZ were less evident. [ABSTRACT FROM AUTHOR]

Abstract: Introduction: The purpose of this study was to analyze the susceptibility of some anaerobic species isolated from a Brazilian population at different periods of time by determining a pattern of development of resistance to frequently prescribed antibiotics in endodontics. Methods: Root canal samples were collected from infected teeth at different periods of time (2000–2002, 2003–2005, and 2007–2008) and microbiologically identified with conventional culture techniques. The susceptibility of Prevotella intermedia/nigrescens, P. oralis, Fusobacterium nucleatum, and P. micra isolated strains was determined by the minimum inhibitory concentration (MIC) of amoxicillin, amoxicillin + clavulanate, benzylpenicillin, clindamycin, erythromycin, and metronidazole by using the E-test method. Results: Amoxicillin and amoxicillin + clavulanate were effective against the majority of species at the different periods of study. Overall, there were low statistical differences regarding the microbial susceptibility between the experimental periods. However, an increase in the anaerobic resistance to penicillin G and clindamycin was observed. Resistance to erythromycin was observed in all species, and there were statistically significant differences between 2000–2002 and 2003–2005 periods for F. nucleatum (P < .05) and between 2003–2005 and 2007–2008 periods for P. intermedia/nigrescens and P. oralis (P < .05). Conclusions: The antimicrobial resistance of anaerobes isolated from primary endodontic infections showed an increase throughout a period of time regarding a specific Brazilian population. [Copyright &y& Elsevier]

Objective. To compare clinical response to initial empiric treatment with oxacillin plus ceftriaxone and amoxicillin plus clavulanic acid in hospitalized children diagnosed with very severe community-acquired pneumonia (CAP). Methods. A prospective randomized clinical study was conducted among children 2 months to 5 years old with a diagnosis of very severe CAP in the pediatric ward of São Paulo State University Hospital in Botucatu, São Paulo, Brazil, from April 2007 to May 2008. Patients were randomly divided into two groups by type of treatment: an oxacillin/ceftriaxone group (OCG, n = 48) and an amoxicillin/clavulanic acid group (ACG, n = 56). Analyzed outcomes were: time to clinical improvement (fever and tachypnea), time on oxygen therapy, length of stay in hospital, need to widen antimicrobial spectrum, and complications (including pleural effusion). Results. The two groups did not differ statistically for age, sex, symptom duration before ad- mission, or previous antibiotic treatment. Time to improve tachypnea was less among ACG patients than OCG patients (4.8 ± 2.2 versus 5.8 ± 2.4 days respectively; P = 0.028), as was length of hospital stay (11.0 ± 6.2 versus 14.4 ± 4.5 days respectively; P = 0.002). There were no statistically significant differences between the two groups for fever improvement time, time on oxygen therapy, need to widen antimicrobial spectrum, or frequency of pleural effusion. Conclusions. Both treatment plans are effective in treating very severe CAP in 2-month- to 5-year-old hospitalized children. The only analyzed outcome that favored amoxicillin/ clavulanic acid treatment was time required to improve tachypnea. [ABSTRACT FROM AUTHOR]

The article discusses the study on the treatment of wastewater through heterogeneous photocatalytic process (HPP) and photo-Fenton process (PFP) using Response Surface Methodology (RSM) to maximize the chemical oxygen demand's (COD) removal efficiency. It cites that the wastewater samples were collected from the University Hospital of Santa Maria (HUSM) in Brazil and that its toxicity was determined through bioassay Artemia salina. To put into effect the photochemical processes for study, a Dewar-like photoreactor was used. It reveals that after 30 minutes of HPP treatment, the samples of hospital effluent with amoxicillin were degraded by 100% and 85% after a 60-minute treatment of PFP. Discussion on the acute lethal toxicity before and after the treatment of wastewater is also offered.

Ninety-one Helicobacter pylori-positive patients with nonulcer dyspepsia were randomized to receive either lansoprazole, amoxicillin, and clarithromycin or lansoprazole and placebo. A validated questionnaire assessed dyspeptic symptoms at baseline and at 3, 6, and 12 months. Endoscopies and biopsies were performed at baseline and at 3 and 12 months. There was an overall trend, although not statistically significant, for a benefit of H. pylori eradication. Of the patients in the antibiotics group, 16 of 46 (35%) had symptomatic improvement, versus 9 of 43 (21%) in the control group (P = 0.164). In a secondary analysis, it was found that of the patients without endoscopic gastric erosions, 15 of 34 (44%) in the antibiotics group and 5 of 33 (15%) of controls had symptomatic improvement (P = 0.015). Helicobacter pylori eradication did not prove to be clinically beneficial, although a tendency to symptomatic benefit was detected. Further studies are necessary to confirm the implications of endoscopic gastric erosions in these patients. [ABSTRACT FROM AUTHOR]

Faster spread of epidemics has turned local concerns into global crises; antimicrobial resistance (AMR) is being considered a major threat to public health in the twenty-first century. Antibiotic misuse plays a great role in accelerated AMR; thus, understanding and discussing consumption patterns has been a trend topic over the past years. Developing countries, such as Brazil, have high growth rates in antibiotic consumption, potentially impacting global environmental safety. This study presents the compiled information from the Brazilian Health Regulatory Agency (ANVISA) on antibiotic dispensation across the country and maps the consumption trends between the years of 2013 and 2016. The most consumed substances were beta-lactams (amoxicillin and cephalexin) and macrolides (azithromycin). National relative growth consumption in the mentioned period was 18%. At the local level, growth of consumption ranged from 4 to 85%, with rampage growth concentrated in the North and Northeast regions. Brazilian laws, such as restriction of over-the-counter sales and mandatory report on dispensation, seem to have little effect on the national antibiotic consumption growth. This phenomenon growth is still elevated if compared with developed countries, demonstrating the need for further surveillance as well as coordinated efforts aiming at antibiotic use and AMR prevention.

Background: The combination of systemic metronidazole (MTZ) and amoxicillin (AMX) with scaling and root planing (SRP) has shown to be an effective periodontal treatment. However, some essential issues associated with the use of these antibiotics remain unanswered, such as the ideal time of administration during the course of periodontal treatment. Although these agents are often prescribed after the healing phase of the SRP procedure, there is biological plausibility to support its use in conjunction with the mechanical treatment. However, to date, no placebo controlled randomized clinical trial (RCT) has directly compared these two protocols. Therefore, the aim of this RCT is to compare the clinical, microbiological and immunological effects of the adjunctive systemic MTZ + AMX administered in different phases of the treatment of severe periodontitis., Methods: Subjects with severe periodontitis (n = 180) are being randomly assigned into three groups (n = 60/group): (i) SRP-only (control group), SRP in combination with 400 mg MTZ + 500 mg AMX, starting (ii) at the first SRP session (active phase group), or (iii) after 3 months of its completion (healing phase group). All volunteers are receiving clinical and microbiological evaluation at baseline, 3, 6 and 12 months, and immunological assessment at baseline and 12 months post-therapy. Nine subgingival biofilm samples are being collected per subject and analyzed for counts and proportions of 40 bacterial species by checkerboard DNA-DNA hybridization, and six gingival crevicular fluid samples are being collected and analyzed for the levels of 20 chemokines by multiplex immunoassay. The primary outcome variable is the number of volunteers reaching the clinical endpoint for treatment (≤ 4 sites with probing depth ≥5 mm) at 1 year post-therapy. Differences in clinical, microbiological and immunological parameters among groups and over time will be evaluated using analysis of variance, analysis of covariance and the Chi-square and Tukey tests. Microbiological and immunological analyses will be performed using adjustments for multiple comparisons. Statistical significance will be set at 5%., Trial Registration: ClinicalTrials.gov , NCT02954393 . Registered on 3 November 2016.