Macrolide resistance among Streptococcus agalactiae during COVID-19 public health emergency in Brazil.

During COVID-19 public health emergence, azithromycin was excessively used in Brazil, as part of a controversial "early treatment", recommended by former national health authorities. Excessive usage of macrolides may increase resistance rates among beta-hemolytic streptococci. Therefore, this study aimed to investigate the occurrence of resistance to erythromycin and clindamycin among Streptococcus agalactiae recovered from February 2020 to May 2023. Bacterial isolates (n = 116) were obtained from pregnant women and submitted to antimicrobial susceptibility testing, investigation of macrolide resistance phenotypes and genotypes, and identification of capsular type. The overall rate of erythromycin not susceptible (NS) isolates was 25.9%, while resistance to clindamycin was 5.2%. Drug efflux, associated with the M phenotype and mef(A) gene, was the prevalent mechanism of resistance (80%). Capsular type Ia was predominant (39.8%), followed by II, III, and V (17.7% each). A higher diversity of types was observed in the last years of the study. Type IV has had an increasing trend over time, being the fourth most common in 2023. The majority of the isolates that expressed the M phenotype presented capsular type Ia, while those with iMLS phenotype presented capsular type V. Despite no causal relationship can be established, azithromycin excessive usage may be a possible factor associated with this higher rate of erythromycin NS isolates, compared with most previous national studies. On the other hand, resistance to clindamycin has not changed significantly. Therefore, in the studied clinical setting, clindamycin remains a useful alternative to intrapartum prophylaxis among penicillin-allergic pregnant women.

Prevalence of Streptococcus agalactiae capsular types among pregnant women in Rio de Janeiro and the impact of a capsular based vaccine

Abstract Streptococcus agalactiae (group B Streptococcus, GBS) remains one major neonatal pathogen, being maternal colonization a risk factor for infection development. Despite effective, the usage of antibiotics to prevent neonatal infections has limitations. The bacterial polysaccharide capsule is a virulence determinant, a target for vaccine directed to pregnant women, and also the most useful epidemiological marker of GBS infections. Capsular polysaccharides are diverse and disease severity varies according to the expressed type. Here, capsular typing of 124 GBS isolates recovered from pregnant women was determined by a multiplex PCR-based method. The most frequent types were Ia (33.0%), II (25.8%) and V (21.8%). Other types found were Ib (8.9%), III (8.9%) and IV (1.6%). While type Ia was prevalent during the whole period (2002-2018), fluctuations in distribution of other types, specially V, were observed over time. Capsular type III, traditionally associated with severe neonatal infections, was poorly detected. Distribution of maternal GBS capsular types in the metropolitan area of Rio de Janeiro, with prevalence of Ia and II, is quite different from other parts of the world. The knowledge about GBS capsular type distribution is essential to predict the theoretical impact of developing capsule-based vaccines in the local population.

Distribution of virulence determinants in Streptococcus agalactiae recovered from different clinical sources.

Streptococcus agalactiae (group B Streptococcus, GBS) is a pathobiont, a member of human microbiota that can change from commensal to pathogen, causing a large spectrum of diseases. This study assessed virulence determinants of 32 GBS isolates recovered from different clinical sources associated with asymptomatic and symptomatic clinical outcomes that present distinct capsular types and antimicrobial resistance profiles. The ability of a unique strain to colonize and cause infection in different subjects was also evaluated. By PFGE analysis, it was observed that a given strain could be associated with both asymptomatic and symptomatic outcomes. Cell wall anchor proteins ß and alpha C encoding genes (bac and bca, respectively) were detected in all capsular type Ib isolates. bca was more frequent among asymptomatic outcome-related isolates, as well as high expression of ß-hemolysin/cytolysin (ß-H/C). Symptomatic outcome-related isolates produced strong biofilm more frequently. All bacterial isolates recovered from urine were strong biofilm producers. In growth experiments, asymptomatic outcome-related isolates grew faster after 2 h until the end of the log phase. Taken together, these findings show virulence genotypic and phenotypic features of GBS from distinct sources, which may be helpful to understand their pathogenic potential and predict different clinical outcomes.

Antimicrobial Resistance among Beta-Hemolytic Streptococcus in Brazil: An Overview.

Streptococcus pyogenes, Streptococcus agalactiae and Streptococcus dysgalactiae subsp. equisimilis (SDSE) are the beta-hemolytic streptococci species with the most clinical relevance to humans. These species are responsible for several infections, ranging from mild to life-threatening diseases. Although resistance to recommended drugs has not been so critical as detected in other species, it has occurred in diverse regions. In Brazil, it is possible to observe an increasing macrolide and lincosamide resistance trend due to the spread of polyclonal strains. Macrolide-lincosamide-streptogramin B (MLS) resistance phenotypes have been prevalent among S. agalactiae and S. pyogenes, while M phenotype (resistance only to macrolides) has prevailed among SDSE resistant isolates. Fluoroquinolone resistance is rare in this country, reported only in S.agalactiae and S.pyogenes. This is due to nucleotide substitutions in gyrA and parC genes. Reduced penicillin susceptibility and vancomycin resistance, detected in other regions, have not yet been reported in Brazil. Tetracycline is not a therapeutical option, and resistance has occurred at high levels, especially among S.agalactiae. These findings highlight the need for continuous monitoring in order to track the occurrence of antimicrobial resistance among beta-hemolytic streptococci species circulating in this country.

Differences in gram-positive bacterial colonization and antimicrobial resistance among children in a high income inequality setting.

BACKGROUND: Staphylococcus aureus and beta-hemolytic streptococci (BHS) diseases disproportionately affect populations in middle/low-income countries. To assess if this disparity is reflected in colonization by these organisms, we compared their colonization frequency among children from different socioeconomic status (SES) communities in a city with high income inequality. METHODS: Between May-August 2014, we collected nasal and throat swabs to investigate S. aureus and BHS colonization among children who attended private and public pediatric clinics. Patients were classified as high SES, middle/low SES, and slum residents. We investigated the antimicrobial resistance profile, the SCCmec types and the presence of PVL genes among methicillin-resistant S. aureus (MRSA). We also examined the antimicrobial resistance profile and serogroups of BHS. RESULTS: Of 598 children, 221 (37%) were colonized with S. aureus, of which 49 (22%) were MRSA. MRSA colonization was higher in middle/low SES (n = 18; 14%) compared with high SES (n = 17; 6%) and slum (n = 14; 8%) residents (p = 0.01). All MRSA strains were susceptible to clindamycin, nitrofurantoin, and rifampin. The highest non-susceptibility frequency (42.9%) was observed to erythromycin. SCCmec type V was only found in isolates from high SES children; types I and II were found only in middle/low SES children. Ten (20%) MRSA isolates carried PVL genes. Twenty-four (4%) children were BHS carriers. All BHS (n = 8) found in high SES children and six (67%) isolates from slum patients belonged to group A. All group B streptococci were from middle/low SES children, corresponding to five (71%) of the seven BHS isolated in this group. BHS isolates were susceptible to all drugs tested. CONCLUSIONS: Children from different SES communities had distinct bacterial colonization profiles, including MRSA carriage. Public health officials/researchers should consider SES when assessing disease transmission and control measures.

Mixed infection and two different resistance profiles of Treponema pallidum to macrolides identified in some clinical specimens of the same patient / Infecção mista e resistência diferente a macrolídeos em Treponema pallidum identificadas por variadas espécimes clínicos em um mesmo paciente

Syphilis represents a global public health problem. The resistance of Treponema pallidum to macrolides is related to the mutation in the 23S rRNA gene (A2058G). We reported a case of secondary syphilis in a 52-year-old man presenting two profiles: the first one of susceptibility, and the other one of resistance, when we analyzed the 23S rRNA gene sequence from two different clinical specimens of the same infectious episode. DNA from T. pallidum from skin biopsy presented resistance profile, whereas T. pallidum DNA from blood presented a profile of susceptibility to macrolides. These results suggest it was mixed infection or reinfection.

A sífilis representa um problema de saúde pública mundial. A resistência de Treponema pallidum aos macrolídeos está relacionada à mutação no gene 23S rRNA (A2058G). Relatamos um caso de sífilis secundária, em um homem de 52 anos, com um perfil de suscetibilidade e outro de resistência, ao analisarmos a sequência do gene 23S rRNA de dois espécimes clínicos diferentes, do mesmo episódio infeccioso. A amostra de DNA de T. pallidum proveniente de raspado dérmico da lesão apresentou um perfil de resistência, enquanto aquele que derivou de sangue apresentou perfil de suscetibilidade aos macrolídeos. Esses resultados sugerem tratar-se de infecção mista ou de reinfecção.

Antimicrobial susceptibility and genetic relationships among Streptococcus dysgalactiae subsp. equisimilis isolates in Rio de Janeiro.

BACKGROUND: Streptococcus dysgalactiae subsp. equisimilis (SDSE) has been increasingly associated with several infectious diseases, ranging from pharyngitis to life-threatening conditions, such as necrotizing fasciitis and streptococcal toxic shock syndrome. However, its molecular epidemiology in some geographical areas remains unclear. METHODS: In this study, 44 isolates of SDSE, recovered from noninvasive infections (37) and from carriage (7), during 2008-2013, were submitted to antimicrobial susceptibility testing, emm typing and pulsed-field gel electrophoresis (PFGE) analysis. RESULTS: All isolates were susceptible to ceftriaxone, levofloxacin, penicillin G and vancomycin. Resistance rates to erythromycin was 18.2% and to clindamycin was 6.8%, while 38.7% of the isolates were tetracycline non-susceptible. Macrolide resistance phenotypes were M (5 isolates), iMLSB (2) and cMLSB (1), associated with mefA/E, ermA and ermB genotypes, respectively. Seventeen emm types with 21 subtypes were found, but 6 types (stG653.0, stC1400.0 with three subtypes, stC839.0, stC36.0 with two subtypes, stG480.0 and stG840.0) were detected in 70.4% of the isolates. Six new emm subtypes were identified (stC1400.12, stC1400.13, emm152.1, emm152.2, stG652.6 and stG6792.5). Twenty-five PFGE profiles were obtained from 39 isolates. CONCLUSIONS: Congruence between both typing systems was observed, since the majority of isolates belonging to a given emm type clustered together by PFGE. Clones (at least 80% similarity) were also observed among isolates with different emm types, probably due to horizontal recombination of the emm gene. Erythromycin-resistant isolates harbored diverse emm genes and generated different PFGE profiles, showing a polyclonal dissemination of such characteristic among SDSE isolates.

Avaliação da colonização por Streptococcus agalactiae em gestantes de alto risco atendidas em Niterói-RJ, Brasil / Evaluation of Streptococcus agalactiae carriage among high risk pregnant women attended in Niterói, RJ, Brazil

O objetivo deste estudo foi avaliar a colonização por Streptococcus agalactiae em gestantes e determinar a susceptibilidade aos antimicrobianos e o tipo capsular das amostras bacterianas isoladas. Foi avaliado um total de 114 gestantes de alto risco, atendidas no serviço de prénatal do Hospital Universitário Antônio Pedro, Universidade Federal Fluminense, entre 1º de setembro de 2013 e 31 de agosto de 2014. Secreções vaginais/anorretais, coletadas com auxílio de swabs, foram cultivadas e as culturas positivas submetidas à identificação da espécie e à determinação do perfil susceptibilidade aos antimicrobianos pela técnica de difusão em agar e o tipo capsular por PCR-multiplex. A taxa de colonização foi de 6,1%, sem diferenças significativas entre as gestantes colonizadas ou não no que diz respeito a idade, grau de instrução e ocorrência de gestações anteriores. Por outro lado, a ausência de infecções bacterianas no momento da coleta foi significativamente associada à colonização por S. agalactiae. As amostras mostraram-se susceptíveis aos antimicrobianos ceftriaxona, clindamicina, eritromicina, levofloxacina, penicilina e vancomicina. Resistência à tetraciclina foi observada em 75% das amostras. Os tipos capsulares encontrados foram Ia (50%) e III (50%). A frequência de colonização por S. agalactiae foi inferior à observada em outros estudos, o que pode estar associado à clientela assistida nesta instituição. As amostras isoladas foram susceptíveis aos antimicrobianos recomendados para a profilaxia da infecção neonatal. Tais amostras albergaram os determinantes genéticos de tipos capsulares associados às infecções neonatais. Estes resultados realçam a necessidade do contínuo monitoramento da colonização a fim de se prevenir a infecção esteptocócica neonatal

Nasopharyngeal carriage, serotype distribution and antimicrobial resistance of Streptococcus pneumoniae among children from Brazil before the introduction of the 10-valent conjugate vaccine.

BACKGROUND: Streptococcus pneumoniae remains a major cause of childhood morbidity and mortality worldwide. Nasopharyngeal colonization plays an important role in the development and transmission of pneumococcal diseases, and infants and young children are considered to be the main reservoir of this pathogen. The aim of this study was to evaluate the rates and characteristics associated with nasopharyngeal carriage, the distribution of serotypes and the antimicrobial resistance profiles of Streptococcus pneumoniae among children in a large metropolitan area in Brazil before the introduction of the 10-valent pneumococcal conjugate vaccine. METHODS: Between March and June 2010, nasopharyngeal swabs were collected from 242 children aged <6 years attending one day care center and the emergency room of a pediatric hospital. Pneumococcal isolates were identified by conventional methods and serotypes were determined by a sequential multiplex PCR assay and/or the Quellung reaction. The antimicrobial susceptibilities of the pneumococci were assessed by the disk diffusion method. MICs for erythromycin and penicillin were also performed. Erythromycin resistance genes were investigated by PCR. RESULTS: The overall colonization rate was 49.2% and it was considerably higher among children in the day care center. Pneumococcal carriage was more common among day care attenders and cohabitants with young siblings. The most prevalent serotypes were 6B, 19F, 6A, 14, 15C and 23F, which accounted for 61.2% of the isolates. All isolates were susceptible to clindamycin, levofloxacin, rifampicin and vancomycin. The highest rate of non-susceptibility was observed for sulphamethoxazole-trimethoprim (51.2%). Penicillin non-susceptible pneumococci (PNSP) accounted for 27.3% of the isolates (MICs of 0.12-4 µg/ml). Penicillin non-susceptibility was strongly associated with serotypes 14 and 23F. Hospital attendance and the presence of respiratory or general symptoms were frequently associated with PNSP carriage. The two erythromycin-resistant isolates (MICs of 2 and 4 µg/ml) belonged to serotype 6A, presented the M phenotype and harbored the mef(A/E) gene. CONCLUSIONS: Correlations between serotypes, settings and penicillin non-susceptibility were observed. Serotypes coverage projected for the 10-valent pneumococcal conjugate vaccine was low (45.5%), but pointed out the potential reduction of PNSP nasopharyngeal colonization by nearly 20%.

Molecular characterization of the first fluoroquinolone resistant strains of Streptococcus agalactiae isolated in Brazil.

Three isolates of Streptococcus agalactiae, recovered from residents of the metropolitan area of Rio de Janeiro with significant bacteriuria, were found to be resistant to levofloxacin. Determination of the minimal inhibitory concentration (MIC) confirmed one isolate as intermediate and two as resistant to levofloxacin. No reduction in levofloxacin MIC was observed with reserpine, indicating that resistance was not caused by an efflux mechanism. Typical point mutations were observed in the quinolone resistance determinant region of gyrA and parC. Other point mutations in parC generated novel altered codons: Ser80→Pro in the intermediate resistance isolate, and Gly128→Asp in a resistant isolate. Through molecular modeling, it was possible to observe that these novel substitutions might not play a role in resistance, since these amino acids were not involved in the antibiotic binding site. Pulsed field gel electrophoresis profiles revealed a non-clonal trend among these isolates. This is the first report of genetic characterization of levofloxacin-resistant S. agalactiae strains in Brazil.

Análise microbiológica de cones de guta-percha disponíveis no mercado brasileiro / Microbiological analysis of gutta-percha cones available in the brazilian market

Objetivo: Analisar a contaminacao na superficie dos cones de guta-percha de diferentes fabricantes disponiveis no mercado nacional e identificar os microrganismos isolados. Metodo: 34 cones de guta-percha acessorios, provenientes de caixas lacradas ou manipuladas, foram analisados. Trinta cones foram divididos, aleatoriamente, em 6 grupos experimentais com 5 cones cada, diferenciados segundo o fabricante e a sua proveniencia (caixas lacradas ou manipuladas). Quatro cones oriundos de caixas lacrada ou manipulada foram utilizados como controles positivo (contaminado com saliva fresca) e negativo (imerso em solucao de hipoclorito de sodio a 5,25% por 1 minuto). As analises microbiologicas foram realizadas submergindo os cones em tubos contendo caldo Brain-Heart Infusion (BHI) e, posteriormente, semeando uma aliquota deste caldo em Agar sangue. A leitura foi realizada atraves da visualizacao de turvacao no caldo ou crescimento de colonias no meio solido. Os dados obtidos foram analisados pelos testes Kruskal-Wallis e Qui-Quadrado com nivel de significancia de 5%. Resultados: Observou-se crescimento bacteriano em 2 amostras. Os generos encontrados foram Staphylococcus e Bacillus. Os resultados indicaram que 6,67% dos cones de guta-percha de embalagens lacradas ou manipuladas estavam contaminados, mas nao houve diferenca estatistica entre os grupos experimentais. Conclusao: Existe um risco de contaminacao dos cones de guta-percha. Portanto estes materiais devem ser desinfetados a fim de garantir a seguranca necessaria para o sucesso do tratamento endodontico.

Objective: To analyze the contamination on the surface of gutta-percha cones from different manufacturers available in the national market and to identify the isolated microorganisms. Method: Thirty-four accessory gutta-percha cones obtained from sealed or violated packages were analyzed. Thirty cones were randomly divided in 6 experimental groups with 5 cones each, according to their manufacturer and origin (sealed or violated packages). Four cones obtained from sealed or violated packages were used as positive (contaminated with fresh saliva) and negative (immersed in 5.25% sodium hypochlorite solution for 1 minute) controls. The microbiological analyses were performed by submerging the cones in tubes containing Brain-Heart Infusion (BHI) broth, and then seeding an aliquot of this broth in agar blood. The analysis was based on the turbidity of the medium or growth of colonies in the solid medium. Data were analyzed by the Kruskal-Wallis and chi-square tests at 5% significance level. Results: There was bacterial growth in 2 samples. Staphylococcus and Bacillus genera were found. The results indicate that 6.67% of the gutta-percha cones from sealed or violated packages were contaminated without statistically significant difference between the experimental groups. Conclusion: There is a risk of contamination of gutta-percha cones. Therefore, these materials must be disinfected to ensure the safety necessary for the success of endodontic treatment.