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.

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.

Ciprofloxacin-Resistant Kerstersia gyiorum Isolated From a Chronic Wound in Brazil: A Case Report.

The presence of Kerstersia gyiorum in lower leg wounds has been reported in case studies from several countries. OBJECTIVE: This study evaluated the antimicrobial susceptibility profile of K gyiorum isolated from a chronic wound. METHODS: An 85-year-old woman with chronic venous insufficiency presented to an intermediate care unit in Niteroi City, Rio de Janeiro, Brazil, with an instep chronic wound of 14 cm² with wound duration of 6 months. K gyiorum was identified by matrix-assisted laser desorption ionization-time of flight, confirmed by 16S rRNA partial sequence analysis, and classified as resistant for ciprofloxacin by reagent strips(minimum inhibitory concentration [MIC] = 32 µg/mL) and the broth macrodilution method (MIC = 8 µg/mL). Intermediate resistance for ciprofloxacin was verified by microscan (MIC = 2 µg/mL). CONCLUSION: The authors identified the first, to their knowledge, lower leg wound with K gyiorum in Brazil and verified that it was ciprofloxacin resistant.

Lactoferrin and lactoferricin B reduce adhesion and biofilm formation in the intestinal symbionts Bacteroides fragilis and Bacteroides thetaiotaomicron.

Several factors affect the composition of species that inhabit our intestinal tract, including mode of delivery, genetics and nutrition. Antimicrobial peptides and proteins secreted in the gastrointestinal tract are powerful tools against bacteria. Lactoferrin (LF) inhibits the growth of several bacterial species, such as Enterobacteriaceae, but may stimulate probiotic bacteria. Activity of LF against gut symbiotic species of the Bacteroides genus could give us insights on how these species colonize the gut. We investigated the effects of the antimicrobial protein lactoferrin and its derived peptide, lactoferricin B on two species of strict anaerobes, opportunistic pathogens that cause diseases in both adults and children, commonly found in the microbiota of the human gastrointestinal tract, Bacteroides fragilis and B. thetaiotaomicron., In vitro biofilm formation and binding to laminin were strongly inhibited by a low concentration of lactoferrin (12.5 µg/ml). Conversely, the growth of the strains in a micro-dilution assay in minimal media with different iron sources was not affected by physiological concentrations (2 mg/ml) of apo-lactoferrin or holo-lactoferrin. The combination of lactoferrin with antibiotics in synergism assays was also negative. The lactoferricin B fragment was also unable to inhibit growth in a similar test with concentrations of up to 32 µg/ml. Resistance to lactoferrin could confer an advantage to these species, even when high amount of this protein is present in the gastrointestinal tract. However, colonization is hampered by the binding and biofilm inhibitiory effect of lactoferrin, which may explain the low prevalence of Bacteroides in healthy babies. Resistance to this antimicrobial protein may help understand the success of these opportunistic pathogens during infection in the peritoneum.

Prevalence, Antimicrobial Susceptibility, and Clonal Diversity of Pseudomonas aeruginosa in Chronic Wounds.

PURPOSE: Our purposes in this study were to (1) identify Pseudomonas aeruginosa strains collected from swabs of chronic wounds, (2) evaluate the susceptibility of P. aeruginosa strains to various antimicrobials, (3) detect the presence of virulence factors exoenzyme S (exoS) and exoenzyme U (exoU) in P. aeruginosa strains, and (4) evaluate wound colonization by P. aeruginosa via pulsed-field gel electrophoresis (PFGE). DESIGN: Descriptive research using a quantitative approach. SAMPLE AND SETTING: Swabs from 43 adults with chronic wounds treated in an outpatient setting in Niterói City, Brazil, were included using convenience sampling. METHODS: Swabs were collected at 2 points during treatment, 30 to 45 days apart. P. aeruginosa isolates were identified using matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry. Antimicrobial susceptibility testing was performed using the disk diffusion method. The presence of exoS and exoU genes was evaluated using polymerase chain reaction. Genotyping diversity was determined through PFGE. RESULTS: Forty-eight P. aeruginosa isolates were detected in chronic wounds, and 3 were multidrug resistant (6%). Resistance to aztreonam and ciprofloxacin was observed in 48% and 27% of isolates, respectively. The presence of the exoS gene was verified in 54% of isolates, and 27% were positive for the exoU gene. In most wounds, P. aeruginosa strains had the same genetic characteristics at the 2 time points analyzed, indicating that the wound beds remained colonized. CONCLUSIONS: P. aeruginosa was present in 75% of tested chronic wound samples, and the same clones persisted for more than 1 month. In addition, most bacteria contained virulence genes that were associated with high potential to establish infection. The use of silver in chronic wounds may be associated with multidrug resistance in P. aeruginosa; therefore, it is important to avoid colonization by these bacteria.

Molecular characterization of multidrug-resistant (MDR) Pseudomonas aeruginosa isolated in a burn center.

OBJECTIVE: The aim of this study was to characterize molecularly multidrug-resistant (MDR) Pseudomonas aeruginosa isolates collected from burn center (BC) patients and environment in a hospital localized in Rio de Janeiro city, RJ, Brazil. METHODS: Thirty-five P. aeruginosa isolates were studied. The antimicrobial resistance was tested by disk diffusion method as recommended by CLSI. The assessment of virulence (exoS and exoU) and resistance (blaPER-1, blaCTX-M, blaOXA-10, blaGES-1, blaVIM, blaIMP, blaSPM-1, blaKPC, blaNDM and blaSIM) genes were achieved through PCR and biofilm forming capacity was determined using a microtiter plates based-assay, as described previously. Genotyping was performed using Multilocus sequence typing (MLST). RESULTS: High rate of P. aeruginosa (71.4%; 25/35) were classified as MDR, of them 64% (16/25) were related to clone A, the most prevalent clone found in the BC studied. A total of eight carbapenems resistant isolates were detected; three belonging to clone A and five carrying the exoU virulence gene. In addition, clone A isolates were also biofilm producers. Two new sequence types (ST) were detected in this study: ST2236, grouped in to clone A; and ST2237, classified in the different clones, displaying carbapenem resistance and exoU virulence gene. CONCLUSION: The high prevalence of biofilm producers and multiresistant P. aeruginosa isolates in BC indicates that prevention programs need to be implemented to avoid infection in highly susceptible patients.

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.

Production of AI-2 is mediated by the S-ribosylhomocystein lyase gene luxS in Bacteroides fragilis and Bacteroides vulgatus.

Quorum sensing is a cell-cell signaling mechanism based on cell density and that involves the production of hormone-like molecules called autoinducers (AI). One of the most studied AIs has been termed AI-2, and its biosynthesis requires the enzyme encoded by luxS. We have previously described for the first time that Bacteroides species can produce molecules with AI-2 activity. In this study, we focus on the detection of luxS and its activity as the AI-2 synthase in Bacteroides species. The strains Bacteroides fragilis B3b and Bacteroides vulgatus ATCC 8482 were selected based on a positive phenotype for AI-2 production and the presence of a putative luxS in the genome, respectively. In order to identify the luxS gene, cloning and heterologous expression strategies were utilized. We demonstrate that both strains contain functional luxS orthologs that can complement AI-2 production in Escherichia coli.

Effect of hospital disinfectants on spores of clinical Brazilian Clostridium difficile strains.

The aim of this study was to evaluate the sporicidal activity of hospital disinfectants against spores of two Brazilian Clostridium difficile ribotypes and the BI/NAP1/027. Our results showed that CloroRio(®) and Cidex Opa(®) were the most efficient agents for eliminating spores of C difficile.

Application of DNA sequence analysis based on five different conserved genes (16S rDNA, rpoB, gdh, est and pgm) for intra-species discrimination of Bacteroides fragilis.

In the past few years, many studies revealed a remarkable genetic variability in Bacteroides fragilis species, and the existence of two divisions was proposed according to presence or absence of the cfiA (metallo-ß-lactamase/carbapenemase) gene. The aim of this study was to evaluate the use of DNA sequence analysis for glutamate dehydrogenase (gdh), phosphoglucomutase (pgm) and esterase (est) metabolic genes, in comparison to RNA polymerase ß subunit (rpoB) and 16S ribosomal RNA (rrs) gene sequencing, to identify the presence of these two groups in seventeen B. fragilis strains. Based on phylogenetic trees, only the est gene sequences generated a classification similar to rrs- and rpoB-genes. On the other hand, the genes pgm and gdh did not allow the discrimination of these divisions. The est gene sequence can be suggested as an additional tool for differentiation of the two groups in B. fragilis, providing highly reproducible and reliable data in B. fragilis taxonomy.

Detection of bla(OXA-23) in Acinetobacter spp. isolated from patients of a university hospital.

INTRODUCTION: Acinetobacter spp. have emerged as notorious pathogens involved in healthcare-associated infections. Carbapenems are important antimicrobial agents for treating infections due to multidrug resistant Acinetobacter spp. Different mechanisms may confer resistance to these drugs in the genus, particularly production of class D carbapenemases. OXA-23-like family has been pointed out as one of the predominant carbapenamases among Acinetobacter. The present work aimed to investigate the occurrence of OXA-23-like carbapenemases among Acinetobacter isolates recovered from patients of a university hospital in Niterói, RJ, Brazil. METHODS: Antimicrobial susceptibility profiles were determined by disk-diffusion. Imipenem resistant isolates were submitted to Modified Hodge Test in order to screen for carbapenemase production, and later to polymerase chain reaction (PCR) to investigate the presence of bla(OXA-23). RESULTS: Imipenem and meropenem resistance rates were 71.4% and 69.7%, respectively. The Modified Hodge Test revealed carbapenemase production among 76 (89.4%) of the 85 imipenem resistant isolates analyzed; according to PCR results, 81 isolates (95.4%) carried the bla(OXA-23) gene. CONCLUSIONS: OXA-23-like enzymes may be an important mechanism of carbapenem resistance among isolates present in the hospital studied.

Presence of the cfxA gene in Bacteroides distasonis.

In this study we investigated the presence of the cfxA gene (encoding a class A beta-lactamase) in 73 strains of the Bacteroides fragilis group belonging to the species B. distasonis (34), B. vulgatus (14), B. thetaiotaomicron (8), B. merdae (6), B. caccae (9) and B. ovatus (2) isolated from human intestinal microflora of healthy children and adults. Employing specific primers to the cfxA gene, a 312-bp amplified fragment was obtained in 2 strains of B. vulgatus and 9 strains, the majority from children, of B. distasonis. The expression of this enzyme was analysed by determining the MICs to cefoxitin and cefotaxime and values varied from 2 to >256 microg/ml of both cefoxitin and cefotaxime. Sequence analysis of the amplicons corresponding to the cfxA gene from B. distasonis and B. vulgatus revealed identical sequences between these isolates and high similarity with other beta-lactamase genes of anaerobes such as cfxA of B. vulgatus (99%) and cfxA2 of Prevotella intermedia (99%), both sequences of which deposited in Genbank under accession numbers U38243 and AF118110, respectively. However, a fragment obtained from a B. distasonis strain (EC17-4) showed a unique RFLP profile and 87% nucleotide similarity with cfxA and cfxA2 genes. These results seem to suggest a dissemination of these resistance determinants among Bacteroides species.