Concerns over the replicability and reproducibility of published research have grown in many research fields, but empirical data to inform policies are still scarce. Biomedical research in Brazil expanded rapidly over the last three decades, with no systematic assessment of the replicability of its findings. With this in mind, we set up the Brazilian Reproducibility Initiative, a multicenter replication of published experiments from Brazilian science using three common experimental methods: the MTT assay, the reverse transcription polymerase chain reaction (RT-PCR) and the elevated plus maze (EPM). A total of 56 laboratories performed 143 replications of 56 experiments; of these, 90 replications of 45 experiments were considered valid by an independent committee. Replication rates for these experiments varied between 20 and 44% according to five predefined criteria. In median terms, ratios between group means were 58% lower in replications than in original experiments, while coefficients of variation were 82% higher. Effect size decrease was smaller for MTT experiments, original results with less variability and those considered more challenging to replicate, while t values for replications were positively correlated with researcher predictions about replicability, and negatively correlated with the rate of publications by the original article’s last author. Deviations from preregistered protocols were very common in replications, most frequently due to reasons inherent to the experimental model or related to infrastructure and logistics. Our results highlight factors that limit the replicability of results published by researchers in Brazil and suggest ways by which this scenario can be improved.

Streptococcus pneumoniae causes serious illnesses, such as pneumonia, bacteremia, and meningitis, mainly in immunocompromised individuals and those of extreme ages. Currently, pneumococcal conjugate vaccines (PCVs) are the best allies against pneumococcal diseases. In Brazil, the 10-valent and 13-valent PCVs have been available since 2010, but the threat of antimicrobial resistance persists and has been changing over time. We conducted a systematic review of the literature with works published since 2000, generating a parallel between susceptibility data on isolates recovered from colonization and invasive diseases before and after the implementation of PCVs for routine childhood use in Brazil. This systematic review was based on the Cochrane Handbook for Systematic Reviews of Interventions and Preferred Reporting Items for Systematic Literature Reviews and Meta-Analyses (PRISMA) guidelines. Despite the inclusion of PCVs at a large scale in the national territory, high frequencies of non-susceptibility to important drugs used in pneumococcal diseases are still observed, especially penicillin, as well as increasing resistance to macrolides. However, there are still drugs for which pneumococci have a comprehensive sensitivity profile.

Objective: This study aimed to search for Enterococcus faecalis in children’s deep carious dentine and characterize their virulence traits. Material and Methods: Eight isolates from 15 carious molars identified by 16S rDNA species-specific PCR as E. faecalis were included. These eight isolates were subject to identification by MALDI‐TOF and characterized regarding: (i) bacterial aggregation and biofilm formation on polystyrene and glass, with/without saliva, as single or dual-species (associated to Streptococcus mutans); (ii) environmental pH measurement before and after 24 h incubation; (iii) acidogenicity; (iv) gelatinase production; (v) macrophage adherence; and (vi) toxicity towards Caenorhabditis elegans. Statistical analyses were performed using two-way ANOVA/Tukey or Fisher’s exact tests. Results: All isolates initially identified as E. faecalis by PCR were correctly identified as Lactobacillus by MALDI-TOF, being designated as Lactobacillus misidentified as Enterococcus (LME). These isolates produced biofilm in the presence of saliva and in the dual-species assays. Bacterial aggregation was only observed in the dual-species model. After 24 h, environmental pH dropped from 7.5 to 4.5 for seven of eight isolates, and to 4.0 in all dual-species models. LME isolates were acidogenic, none of them produced gelatinase or adhered to macrophages, but all presented toxicity towards C. elegans. Conclusions: No E. faecalis were identified in the children’s caries lesions. All LME isolates presented important virulence traits, including biofilm formation and high acidogenicity, which cause enamel demineralization, that might increase the risk of dental caries in children carrying LME. Thus, the correct identification and in-depth virulence characterization of microorganisms isolated from dental caries are important to understand the dynamics of this disease.

Introdução: Paenibacillus stellifer está amplamente distribuído na natureza, mas sua patogenicidade não foi relatada, desde que foi identificado pela primeira vez em 2003. Objetivos: Este trabalho objetivou identificar bacilos Gram-variáveis, isolados em casos de infecções relacionadas à assistência à saúde, no período de Setembro/2015 a Agosto/2016, em um hospital da região serrana do Rio de Janeiro, Brasil e avaliar o perfil de sensibilidade destes microrganismos a antibióticos comumente empregados na prática clínica. Métodos: Inicialmente, os microrganismos foram identificados a partir de testes bioquímicos convencionais e o resultado foi confirmado através da técnica de Matrix-Assisted Laser Desorption/Ionization — Time of Flight (MALDITOF). O teste de sensibilidade aos antimicrobianos foi realizado de acordo com as recomendações do Clinical and Laboratory Standards Institute. Resultados: Foram analisadas 105 amostras: 59 secreções de feridas cirúrgicas e 46 hemoculturas. Bacilos Gram-variáveis foram identificados em duas amostras de secreção de ferida cirúrgica (3,39%) e em duas hemoculturas (4,35%). Paenibacillus stellifer foi o microrganismo isolado nas quatro amostras e apresentou sensibilidade perante todas as drogas testadas. Conclusão: P. stellifer é um microrganismo de origem ambiental e não compõe a microbiota humana. De acordo com o conhecimento atual, esta é a primeira identificação de P. stellifer, como agente etiológico de infecções de ferida cirúrgica no mundo, e bacteremia no Brasil. Por fim, destaca-se o fato de que microrganismos normalmente encontrados no ambiente são capazes de causar infecções, quando presentes no ambiente hospitalar.

Resistance expression can occur as a consequence of irrational use of antibiotics, since this implies dissemination of subinhibitory concentration (sub-MICs) in different environments and generates a selective pressure. The study aimed to evaluate the in vitro influence of selective pressure on antibiotic resistance expression in two oxacillin-susceptible mecA -positive Staphylococcus aureus (OS-MRSA), through exposure to oxacillin sub-MICs. One heteroresistant OS-MRSA strain and a non-heteroresistant strain, both isolated from nasal colonization were exposed to two-fold serial dilutions of oxacillin (0,125 a 256 μg/mL) during seven consecutive days. Disc diffusion test was used to determine the susceptibility to several antibiotics and population analysis profile (PAP) was used to evaluate the expression of oxacillin resistance before and after antibiotic exposure. Susceptibility to non-β-lactam antibiotics was not altered but changes in phenotypic expression of penicillin and oxacillin resistance were observed. Both OS-MRSA strains began to express homoresistance (oxacillin MIC = 256 μg/mL) and had no penicillin zone inhibition after induction, different from that was observed before oxacillin exposure, which suggested increased in β-lactamase production. In vitro selective pressure with oxacillin stimulated β-lactamase production and led phenotypic expression of oxacillin resistance in heteroresistant and non-heteroresistant OS-MRSA, which became homoresistant. This reinforces the impact that irrational use of antibiotics has on individuals colonized by S. aureus and on the population, emphasizing that the emergence and spread of resistance to antibiotics represent a process of evolution in response to selective antimicrobial pressure.

Background: For over 70 years, guidelines have recommended antibiotics for infective endocarditis (IE) prophylaxis before dental procedures, focusing on oral streptococci. Objectives: Our in silico study aimed to evaluate the potential resistance of oral streptococci against prophylactic antibiotics used before invasive dental procedures to prevent IE. Methods: The genomic assemblies and metadata of Streptococcus IE isolates were searched using specific terms in BioSample and RefSeq databases. Their antimicrobial resistance phenotypes for 91 drugs belonging to 22 different classes were predicted with ResFinder and analysed regarding the recommended IE dental prophylactic antibiotics, focusing on the oral streptococci assemblies. Results: Among the 258 Streptococcus isolates dating from 1935 to 2021 from 12 countries, 79.46% were classified as oral streptococci, and 38.37% of the 258 assemblies carried resistance genes to at least one antimicrobial. Seven isolates carried the transposon Tn6331, which can confer resistance to aminoglycosides, macrolides, lincosamides, streptogramins and tetracyclines. Within the oral Streptococcus strains, none carried resistance genes to amoxicillin, but potential resistance to azithromycin (24.88%) and doxycycline (16.59%) was observed. Conclusions: Our in silico study showed that none of the oral Streptococcus assemblies from IE carried resistance genes to the primary regimen recommended for IE prophylaxis following invasive dental procedures. However, several assemblies were potentially resistant to alternative prophylactic regimens for patients allergic to penicillin or ampicillin.