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Streptococcus agalactiae (group B Streptococcus, GBS) is a major pathogen in humans and animals. Pili and biofilm may be important virulence factors in this bacterial species. Here, biofilm production and the distribution of pilus variants among 134 GBS isolates from human and animal sources were evaluated. Biofilm production was significantly enhanced in 1% glucose-supplemented medium (p < 0.05). Using this medium, most GBS strains were strong biofilm producers. Biomass was mainly composed of proteins, followed by extracellular DNA, while polysaccharides represented a minor portion. All GBS strains presented at least one pilus variant. PI-2a was the most common among human GBS while PI-2b was the most common among animal isolates. Human GBS harboring PI-2b and animal GBS harboring PI-2a presented significantly reduced biofilm production (p = 0.0033). In conclusion, strong biofilm production seems to be a common characteristic in GBS, and association of the clinical source with the pilus variant may be crucial for this.
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Biofilmes/crescimento & desenvolvimento , Fímbrias Bacterianas/genética , Infecções Estreptocócicas/microbiologia , Streptococcus agalactiae/isolamento & purificação , Animais , Proteínas de Bactérias/genética , DNA Bacteriano , Variação Genética , Humanos , Streptococcus agalactiae/genética , Streptococcus agalactiae/crescimento & desenvolvimento , Fatores de Virulência/genéticaRESUMO
Streptococcus agalactiae (Group B Streptococcus; GBS) is a leading cause of neonatal invasive disease worldwide. GBS can colonize the human gastrointestinal and genitourinary tracts, and the anovaginal colonization of pregnant women is the main source for neonatal infection. Streptococcus anginosus, in turn, can colonize the human upper respiratory, gastrointestinal, and genitourinary tracts but has rarely been observed causing disease. However, in the last years, S. anginosus has been increasingly associated with human infections, mainly in the bloodstream and gastrointestinal and genitourinary tracts. Although anovaginal screening for GBS is common during pregnancy, data regarding the anovaginal colonization of pregnant women by S. anginosus are still scarce. Here, we show that during the assessment of anovaginal GBS colonization rates among pregnant women living in Rio de Janeiro, Brazil, S. anginosus was also commonly detected, and S. anginosus isolates presented a similar colony morphology and color pattern to GBS in chromogenic media. GBS was detected in 48 (12%) while S. anginosus was detected in 17 (4.3%) of the 399 anovaginal samples analyzed. The use of antibiotics during pregnancy and history of urinary tract infections and sexually transmitted infections were associated with the presence of S. anginosus. In turn, previous preterm birth was associated with the presence of GBS (p < 0.05). The correlation of GBS and S. anginosus with relevant clinical features of pregnant women in Rio de Janeiro, Brazil, highlights the need for the further investigation of these important bacteria in relation to this special population.
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Neisseria gonorrhoeae is a global threat to public health due to the accumulation of antimicrobial resistance mechanisms. ST-1901 is an internationally important sequence type (ST) because of its high incidence and the usual occurrence of chromosomally determined resistance. In this study, we describe the evolution of the ST-1901 and its single locus variants in Rio de Janeiro from 2006 to 2022. We analyzed 82 N. gonorrhoeae isolates according to antimicrobial susceptibility profile, resistance mechanisms, molecular typing, and phylogenetics. Six different single locus variants were detected. Phylogenetic analysis identified five clades, which share similar characteristics. Resistance rates for penicillin and tetracycline decreased due to the lower occurrence of resistance plasmids, but intermediary resistance to penicillin rose. Resistance to ciprofloxacin remained high throughout all clades and the years of the study. Regarding resistance to azithromycin, alterations in mtrR promoter and gene, and 23S rRNA encoding gene rrl were detected, with a notable rise in the incidence of C2611T mutations in more recent years occurring in 4 out of 5 clades. In contrast, beta-lactam resistance associated penA 34 mosaic was found only in one persisting clade (Clade D), as well as unique G45D and A39T mutations in mtrR gene and its promoter (Nm-Like) were found in only Clade B. Taken together, these data suggest that ST-1901, a persistently circulating lineage of N. gonorrhoeae in Rio de Janeiro, has undergone changes over the years and may evolve to develop resistance to the current recommended dual therapy adopted in Brazil, ceftriaxone and azithromycin.
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BACKGROUND: A novel variant of the ST1-SCCmecIV methicillin-resistant Staphylococcus aureus (MRSA) lineage, mostly associated with nosocomial bloodstream infections (BSI), has emerged in Rio de Janeiro. Bacterial biofilm has been considered a major virulence factor in central venous catheter-associated BSI. The mechanisms involved in biofilm formation/accumulation are multifactorial and complex. Studies have suggested that biofilm production was affected in vitro and vivo for agr-null mutants of S. aureus. RESULTS: The impact of naturally occurring inhibition of agr signaling on virulence profiles and infections associated with the ST1 variant was investigated. agr dysfunction was detected in a significant percentage (13%) of the isolates with concomitant increase in biofilm accumulation in vitro and in vivo, and enhanced ability to adhere to and invade airway cells. The biofilm formed by these ST1 isolates was ica-independent and proteinaceous in nature. In fact, the improved colonization properties were paralleled by an increased expression of the biofilm-associated genes fnbA, spa and sasG. The transcription of sarA, a positive regulator of agr, was two-times reduced for the agr-dysfunctional MRSA. Remarkably, the agr inhibition was genetically stable. Indeed, agr-dysfunctional isolates succeed to colonize and cause both acute and chronic infections in hospitalized patients, and also to effectively accumulate biofilm in a mouse subcutaneous catheter implant model. CONCLUSION: The ability of agr-dysfunctional isolates to cause infections in humans and to form biofilm in the animal model suggests that therapeutic approaches based on agr-inactivation strategies are unlikely to be effective in controlling human-device infections caused by ST1 isolates. The increased biofilm accumulation associated with the acquisition of multiple antimicrobial resistant traits might have influenced (at least in part) the expansion of this USA400 related clone in our hospitals.
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Biofilmes/crescimento & desenvolvimento , Infecções Relacionadas a Cateter/microbiologia , Staphylococcus aureus Resistente à Meticilina/fisiologia , Staphylococcus aureus Resistente à Meticilina/patogenicidade , Infecções Estafilocócicas/microbiologia , Transativadores/deficiência , Animais , Aderência Bacteriana , Proteínas de Bactérias , Brasil , Modelos Animais de Doenças , Endocitose , Genótipo , Humanos , Masculino , Staphylococcus aureus Resistente à Meticilina/classificação , Staphylococcus aureus Resistente à Meticilina/isolamento & purificação , Camundongos , Camundongos Endogâmicos BALB C , Tipagem Molecular , VirulênciaRESUMO
OBJECTIVES: An aqueous extract and fraction from the marine sponge Petromica citrina have antibacterial activity. We performed a chemical and biological characterization of the antibiotic substance from P. citrina and investigated its mode of action on Staphylococcus aureus cells. METHODS: The inhibitory activity of the aqueous extract of P. citrina was determined against 14 bacteria belonging to type strains and clinical antibiotic-resistant strains. The aqueous extract was fractionated under bioassay guidance and the bioactive substance was identified by its (1)H-NMR, (13)C-NMR and mass spectra. The MIC and the MBC of this substance were determined. This substance was also subjected to cytotoxic bioassays. The mode of action on S. aureus cells was investigated by light and transmission electron microscopy analysis. RESULTS: P. citrina showed a large spectrum of activity against type strains and resistant-bacteria such as S. aureus, Staphylococcus epidermidis, Enterococcus faecalis, Mycobacterium fortuitum and Neisseria gonorrhoeae. The aqueous extract was fractionated and halistanol trisulphate (24ε,25-dimethylcholestane-2ß,3α,6α-triol trisodium sulphate) was isolated for the first time from P. citrina. Halistanol trisulphate had a bactericidal effect on exponentially growing S. aureus cells at the MIC (512 mg/L). Cytotoxicity biossays showed moderate toxicity against cancer cell line L929 (fibrosarcoma). This substance apparently acts by damaging the cell membrane, with subsequent cell lysis. CONCLUSIONS: Halistanol trisulphate is a broad-spectrum antibiotic isolated from P. citrina with a mode of action involving disruption of the cytoplasmic membrane. It is a new candidate for research on antibacterial substances.
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Antibacterianos/isolamento & purificação , Antibacterianos/farmacologia , Bactérias/efeitos dos fármacos , Poríferos/química , Esteróis/isolamento & purificação , Esteróis/farmacologia , Animais , Antibacterianos/química , Bactérias/citologia , Extratos Celulares/química , Extratos Celulares/isolamento & purificação , Extratos Celulares/farmacologia , Linhagem Celular Tumoral/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Fracionamento Químico , Espectroscopia de Ressonância Magnética , Camundongos , Testes de Sensibilidade Microbiana , MicroscopiaRESUMO
We assessed fluconazole susceptibility in 52 Candida tropicalis clinical strains using seven antifungal susceptibility methods, including broth microdilution (BMD) [standard M27 A3 (with neutral and acid pH), ATB Fungus 3, Vitek 2 system and flow cytometric analysis] and agar-based methods (disk diffusion and E-test). Trailing growth, detection of cell-associated secreted aspartic proteases (Saps) and morphological and ultrastructural traits of these clinical strains were also examined. The ranges of fluconazole 24 h-minimum inhibitory concentration (MIC) values were similar among all methods. The essential agreement among the methods used for MIC determinations was excellent and all methods categorised all strains as susceptible, except for one strain that showed a minor error. The presence of the trailing effect was assessed by six methods. Trailing positivity was observed for 86.5-100% of the strains. The exception was the BMD-Ac method where trailing growth was not observed. Morphological and ultrastructural alterations were detected in C. tropicalis trailing cells, including mitochondrial swelling and cell walls with irregular shapes. We tested the production of Saps in 13 C. tropicalis strains expressing trailing growth through flow cytometry. Our results showed that all of the C. tropicalis strains up-regulated surface Sap expression after 24 h or 48 h of exposure to fluconazole, which was not observed in untreated yeast strains. We concluded that C. tropicalis strains expressing trailing growth presented some particular features on both biological and ultrastructural levels.
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Antifúngicos/farmacologia , Candida tropicalis/efeitos dos fármacos , Fluconazol/farmacologia , Candida tropicalis/crescimento & desenvolvimento , Candida tropicalis/ultraestrutura , Humanos , Testes de Sensibilidade Microbiana/métodos , Microscopia Eletrônica de Transmissão , Fatores de TempoRESUMO
Streptococcus dysgalactiae subsp. dysgalactiae (SDSD) is an important agent of bovine mastitis. This infection causes an inflammatory reaction in udder tissue, being the most important disease-causing significant impact on the dairy industry. Therefore, it leads to an increase in dairy farming to meet commercial demands. As a result, there is a major impact on both the dairy industry and the environment including global warming. Recurrent mastitis is often attributed to the development of bacterial biofilms, which promote survival of sessile cells in hostile environments, and resistance to the immune system defense and antimicrobial therapy. Recently, we described the in vitro biofilm development on abiotic surfaces by bovine SDSD. In that work we integrated microbiology, imaging, and computational methods to evaluate the biofilm production capability of SDSD isolates on abiotic surfaces. Additionally, we reported that bovine SDSD can adhere and internalize human cells, including human epidermal keratinocyte (HEK) cells. We showed that the adherence and internalization rates of bovine SDSD isolates in HEK cells are higher than those of a SDSD DB49998-05 isolated from humans. In vivo, bovine SDSD can cause invasive infections leading to zebrafish morbidity and mortality. In the present work, we investigated for the first time the capability of bovine SDSD to develop biofilm in vivo using a murine animal model and ex-vivo on human HEK cells. Bovine SDSD isolates were selected based on their ability to form weak, moderate, or strong biofilms on glass surfaces. Our results showed that SDSD isolates displayed an increased ability to form biofilms on the surface of catheters implanted in mice when compared to in vitro biofilm formation on abiotic surface. A greater ability to form biofilm in vitro after animal passage was observed for the VSD45 isolate, but not for the other isolates tested. Besides that, in vitro scanning electron microscopy demonstrated that SDSD biofilm development was visible after 4 hours of SDSD adhesion to HEK cells. Cell viability tests showed an important reduction in the number of HEK cells after the formation of SDSD biofilms. In this study, the expression of genes encoding BrpA-like (biofilm regulatory protein), FbpA (fibronectin-binding protein A), HtrA (serine protease), and SagA (streptolysin S precursor) was higher for biofilm grown in vivo than in vitro, suggesting a potential role for these virulence determinants in the biofilm-development, host colonization, and SDSD infections. Taken together, these results demonstrate that SDSD can develop biofilms in vivo and on the surface of HEK cells causing important cellular damages. As SDSD infections are considered zoonotic diseases, our data contribute to a better understanding of the role of biofilm accumulation during SDSD colonization and pathogenesis not only in bovine mastitis, but they also shed some lights on the mechanisms of prosthesis-associated infection and cellulitis caused by SDSD in humans, as well.
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Mastite Bovina , Animais , Biofilmes , Catéteres , Bovinos , Modelos Animais de Doenças , Feminino , Humanos , Queratinócitos , Mastite Bovina/microbiologia , Camundongos , Streptococcus , Peixe-ZebraRESUMO
Streptococcus agalactiae (Group B Streptococcus , GBS) is a major agent of perinatal infections. Biofilms have been associated with GBS colonization and disease, as well as with infection persistence and recurrence. Although GBS remains susceptible to beta-lactams, it is still unknown how sessile cells respond to these antibiotics. Here, we evaluated the effect of different concentrations of penicillin (3-48 mg/L) on in vitro biofilm formation by four GBS strains belonging to serotype Ia/clonal complexes23 that were recovered from the oropharynx or urine of pregnant women and were previously characterized as strong biofilm producers. All four GBS strains were fully susceptible to penicillin (minimum inhibitory concentration = 0.023 mg/L), but penicillin was not able to fully prevent biofilm formation by these GBS strains. Biofilms formed in the presence of penicillin had reduced biomasses and thickness, but they were still classified as strong. Penicillin significantly reduced the density of live cells, but higher penicillin concentrations did not lead to improved prevention of biofilm formation. Biofilms formed in the presence of penicillin had no channels or long cocci chains observed in penicillin-free biofilms. Overall, results highlight the concerning possible impacts of biofilm formation in penicillin-based treatment and preventive strategies of GBS infections, even when the bacterial strain involved is fully antibiotic-susceptible.
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Infecções Estreptocócicas , Streptococcus agalactiae , Antibacterianos/farmacologia , Biofilmes , Feminino , Humanos , Testes de Sensibilidade Microbiana , Penicilinas/farmacologia , Gravidez , Sorogrupo , Infecções Estreptocócicas/tratamento farmacológico , Infecções Estreptocócicas/microbiologiaRESUMO
Group B Streptococcus (GBS) is a leading cause of neonatal infections. The genitourinary and gastrointestinal tract of pregnant women are the main source of transmission to newborns. This work investigated the prevalence and characterized GBS from pregnant women in Rio de Janeiro, Brazil, comparing the periods before (January 2019 to March 2020; 521) and during (May 2020 to March 2021; 285) the COVID-19 pandemic. GBS was detected in 10.8% of anovaginal samples. Considering scenarios before and during the pandemic, GBS colonization rate significantly decreased (13.8% vs. 5.3%; p = 0.0001). No clinical and sociodemographic aspect was associated with GBS carriage (p > 0.05). A total of 80%, 13.8% and 4.6% GBS strains were non-susceptible to tetracycline, erythromycin and clindamycin, respectively. Serotype Ia was the most frequent (47.7%), followed by V (23.1%), II (18.4%), III (7.7%) and Ib (3.1%). An increasing trend of serotypes Ib and V, as well as of antimicrobial resistance rates, and a decreasing trend of serotypes II and III, were observed after the pandemic onset, albeit not statistically significant (p > 0.05). The reduction in GBS colonization rates and alterations in GBS serotypes and resistance profiles during the pandemic were not due to changes in the sociodemographic profile of the population. Considering that control and preventive measures related to the COVID-19 pandemic onset have impacted other infectious diseases, these results shed light on the need for the continuous surveillance of GBS among pregnant women in the post-pandemic era.
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Streptococcus agalactiae isolates are more common among pregnant women, neonates and nonpregnant adults with underlying diseases compared to other demographic groups. In this study, we evaluate the genetic and phenotypic diversity in S. agalactiae strains from Rio de Janeiro (RJ) that were isolated from asymptomatic carriers. We analysed these S. agalactiae strains using pulsed-field gel electrophoresis (PFGE), serotyping and antimicrobial susceptibility testing, as well as by determining the macrolide resistance phenotype, and detecting the presence of the ermA/B, mefA/E and lnuB genes. The serotypes Ia, II, III and V were the most prevalent serotypes observed. The 60 strains analysed were susceptible to penicillin, vancomycin and levofloxacin. Resistance to clindamycin, chloramphenicol, erythromycin, rifampin and tetracycline was observed. Among the erythromycin and/or clindamycin resistant strains, the ermA, ermB and mefA/E genes were detected and the constitutive macrolides, lincosamides and streptogramin B-type resistance was the most prevalent phenotype observed. The lnuB gene was not detected in any of the strains studied. We found 56 PFGE electrophoretic profiles and only 22 of them were allocated in polymorphism patterns. This work presents data on the genetic diversity and prevalent capsular serotypes among RJ isolates. Approximately 85% of these strains came from pregnant women; therefore, these data may be helpful in developing future prophylaxis and treatment strategies for neonatal syndromes in RJ.
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Proteínas de Bactérias/genética , Variação Genética/genética , Streptococcus agalactiae/genética , Adulto , Antibacterianos/farmacologia , Portador Sadio , Eletroforese em Gel de Campo Pulsado , Feminino , Genótipo , Humanos , Proteínas de Membrana/genética , Metiltransferases/genética , Testes de Sensibilidade Microbiana , Fenótipo , Gravidez , Sorotipagem , Streptococcus agalactiae/efeitos dos fármacos , Streptococcus agalactiae/isolamento & purificaçãoRESUMO
INTRODUCTION: Salmonella enterica serovar Panama belongs to the D1 serogroup and is frequently associated with nontyphoidal salmonellosis in humans. This study aimed to characterize isolates collected from Northeast Brazil by phenotypic and molecular methods. METHODS: Forty four S. Panama strains were examined for antimicrobial susceptibility, virulence genes, and pulsed field gel electrophoresis (PFGE) types. RESULTS: All strains were susceptible to antibiotics (except for streptomycin), presented classical virulence factors, and could be clustered into four groups and 18 pulsotypes. CONCLUSIONS: This work calls for continuous surveillance for the emergence of antibiotic resistance and new clones in a geographical area.
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Salmonella enterica/genética , Fatores de Virulência/genética , Animais , Antibacterianos/farmacologia , Brasil , Farmacorresistência Bacteriana Múltipla , Eletroforese em Gel de Campo Pulsado , Variação Genética , Humanos , Testes de Sensibilidade Microbiana , Salmonella enterica/efeitos dos fármacos , Salmonella enterica/isolamento & purificação , Salmonella enterica/patogenicidadeRESUMO
Salmonella infections usually occur as gastroenteritis that is generally self-limited. However, some serotypes of Salmonella can cause severe extra-intestinal infections, such as bacteremia and meningitis. Here, we report the first Salmonella Panama case of meningitis in 4-month-old male newborn in Brazil. The invasive strain isolated was susceptible to all antimicrobial agents tested. The genes agfA, fimA, invA, sfbA, phoP, and slyA were detected using polymerase chain reactions. These findings are relevant and physicians should be alert to the possibility of meningitis in newborns due to S. Panama, which can present a high rate of mortality or recurrence of infection.
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Meningites Bacterianas/microbiologia , Salmonella enterica/genética , Brasil/epidemiologia , Pré-Escolar , Humanos , Masculino , Meningites Bacterianas/diagnóstico , Meningites Bacterianas/epidemiologia , Reação em Cadeia da Polimerase , Salmonella enterica/isolamento & purificação , SorotipagemAssuntos
Mastite Bovina , Infecções Estreptocócicas , Animais , Feminino , Gravidez , Humanos , Bovinos , Streptococcus agalactiae/genética , Gestantes , Brasil/epidemiologia , Infecções Estreptocócicas/epidemiologia , Infecções Estreptocócicas/veterinária , Infecções Estreptocócicas/microbiologia , Mastite Bovina/microbiologia , Leite/microbiologiaRESUMO
Colonization by Group B Streptococcus (GBS) is highly prevalent among pregnant women, with prevalence rates ranging between 4% and 30%. The infection may be transmitted vertically and may result in serious neonatal consequences. In the period from November 2003 to May 2004, a cross-sectional study was carried out among 316 parturients at the Jundiaí Teaching Hospital to establish the prevalence of genital GBS colonization, to identify the factors associated with colonization and the characteristic phenotypes of these streptococci. Samples from rectal and vaginal areas were collected for selective culture in Todd-Hewitt broth. Susceptibility to 7 antimicrobial agents was tested using the antibiotic diffusion disk technique, and the isolated strains were classified using specific antisera. The prevalence of GBS colonization was 14.6%. No strain was resistant to penicillin, ampicillin, erythromycin or nitrofurantoin. The majority of strains were sensitive to cephalothin. Greatest resistance was to gentamicin (76.1%), followed by clindamycin (17.4%). The most frequent serotype was Ib (23.9%), followed by serotypes II and Ia (19.6% and 17.4%, respectively). There was no correlation between serotype and greater antimicrobial resistance. In conclusion, the prevalence of GBS in parturients was high and penicillin continues to be the drug of choice for intrapartum prophylaxis. The most frequent serotype (Ib) found in this study differs from those found in the majority of studies carried out in other countries, revealing the need to identify prevalent serotypes in each region so that specific vaccines can be designed.
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Antibacterianos/farmacologia , Portador Sadio/microbiologia , Complicações Infecciosas na Gravidez/microbiologia , Infecções Estreptocócicas/microbiologia , Streptococcus agalactiae/isolamento & purificação , Adulto , Estudos Transversais , Feminino , Humanos , Testes de Sensibilidade Microbiana , Fenótipo , Gravidez , Reto/microbiologia , Fatores de Risco , Sorotipagem , Streptococcus agalactiae/classificação , Streptococcus agalactiae/efeitos dos fármacos , Vagina/microbiologiaRESUMO
Neisseria gonorrhoeae is the agent of gonorrhea, a sexually transmitted infection with an estimate from The World Health Organization of 78 million new cases in people aged 15-49 worldwide during 2012. If left untreated, complications may include pelvic inflammatory disease and infertility. Antimicrobial treatment is usually effective; however, resistance has emerged successively through various molecular mechanisms for all the regularly used therapeutic agents throughout decades. Detection of antimicrobial susceptibility is currently the most critical aspect for N. gonorrhoeae surveillance, however poorly structured health systems pose difficulties. In this review, we compiled data from worldwide reports regarding epidemiology and antimicrobial resistance in N. gonorrhoeae, and highlight the relevance of the implementation of surveillance networks to establish policies for gonorrhea treatment.
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Farmacorresistência Bacteriana , Gonorreia/microbiologia , Neisseria gonorrhoeae/efeitos dos fármacos , Animais , Gonorreia/epidemiologia , Gonorreia/história , História do Século XX , História do Século XXI , Humanos , Neisseria gonorrhoeae/classificação , Neisseria gonorrhoeae/genética , Neisseria gonorrhoeae/isolamento & purificaçãoRESUMO
Staphylococcus saprophyticus is an important agent of urinary tract infection (UTI) in young women, but information about this pathogen in human microbiota and in common environment is lacking. The aim of this study was to characterize S. saprophyticus isolates from genitoanal microbiota of 621 pregnant women, 10 minas cheese packs, and five beaches in Rio de Janeiro city and compare PFGE profiles of these isolates with five UTI PFGE clusters described in this city. We investigated 65 S. saprophyticus isolates from microbiota, 13 from minas cheese, and 30 from beaches and 32 UTI isolates. Antimicrobial resistance was determined by disk diffusion, MIC by agar dilution, and PCR. Erythromycin-resistance genes erm(C), msr(A), msr(B), mph(C), and lin(A) were found in 93% of isolates. Trimethoprim-sulfamethoxazole resistance correlated with dfrG or dfrA genes. Three cefoxitin-resistant isolates carried the mecA gene. All isolates obtained from cheese were susceptible to all antimicrobial agents. Six of 10 pregnant women with >1 isolate had monoclonal colonization. Isolates from pregnant women shared 100% similarity with UTI PFGE cluster types A and E obtained almost 10 years previously, suggesting temporal persistence of S. saprophyticus. Antimicrobial resistance of beach isolates reflected the profiles of human isolates. Taken together, results indicate a shared source for human and environmental isolates.
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Staphylococcus aureus ica-independent biofilms are multifactorial in nature, and various bacterial proteins have been associated with biofilm development, including fibronectin-binding proteins A and B, protein A, surface protein SasG, proteases, and some autolysins. The role of extracellular DNA (eDNA) has also been demonstrated in some S. aureus biofilms. Here, we constructed a Tn551 library, and the screening identified two genes that affected biofilm formation, lrgB and yycI. The repressive effect of both genes on the development of biofilm was also confirmed in knockout strains constructed by allelic recombination. In contrast, the superexpression of either lrgB or yycI by a cadmium-inducible promoter led to a decrease in biofilm accumulation. Indeed, a significant increase in the cell-lysis dependent eDNA release was detected when lrgB or yycI were inactivated, explaining the enhanced biofilm formed by these mutants. In fact, lrgB and yycI genes belong to distinct operons that repress bacterial autolysis through very different mechanisms. LrgB is associated with the synthesis of phage holin/anti-holin analogues, while YycI participates in the activation/repression of the two-component system YycGF (WalKR). Our in vivo data suggest that autolysins activation lead to increased bacterial virulence in the foreign body animal model since a higher number of attached cells was recovered from the implanted catheters inoculated with lrgB or yycI knockout mutants.
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Proteínas de Bactérias/genética , Biofilmes/crescimento & desenvolvimento , DNA Bacteriano/metabolismo , Infecções Estafilocócicas/microbiologia , Staphylococcus aureus/fisiologia , Fatores de Virulência/genética , Animais , Bacteriólise , Modelos Animais de Doenças , Regulação Bacteriana da Expressão Gênica , Biblioteca Gênica , Humanos , Técnicas In Vitro , Camundongos , Mutagênese Insercional , Infecções Estafilocócicas/genética , Staphylococcus aureus/genética , Staphylococcus aureus/isolamento & purificaçãoRESUMO
Abstract INTRODUCTION Salmonella enterica serovar Panama belongs to the D1 serogroup and is frequently associated with nontyphoidal salmonellosis in humans. This study aimed to characterize isolates collected from Northeast Brazil by phenotypic and molecular methods. METHODS Forty four S. Panama strains were examined for antimicrobial susceptibility, virulence genes, and pulsed field gel electrophoresis (PFGE) types. RESULTS All strains were susceptible to antibiotics (except for streptomycin), presented classical virulence factors, and could be clustered into four groups and 18 pulsotypes. CONCLUSIONS This work calls for continuous surveillance for the emergence of antibiotic resistance and new clones in a geographical area.
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Animais , Salmonella enterica/genética , Fatores de Virulência/genética , Variação Genética , Brasil , Testes de Sensibilidade Microbiana , Eletroforese em Gel de Campo Pulsado , Salmonella enterica/isolamento & purificação , Salmonella enterica/efeitos dos fármacos , Salmonella enterica/patogenicidade , Farmacorresistência Bacteriana Múltipla , Antibacterianos/farmacologiaRESUMO
Abstract Salmonella infections usually occur as gastroenteritis that is generally self-limited. However, some serotypes of Salmonella can cause severe extra-intestinal infections, such as bacteremia and meningitis. Here, we report the first Salmonella Panama case of meningitis in 4-month-old male newborn in Brazil. The invasive strain isolated was susceptible to all antimicrobial agents tested. The genes agfA, fimA, invA, sfbA, phoP, and slyA were detected using polymerase chain reactions. These findings are relevant and physicians should be alert to the possibility of meningitis in newborns due to S. Panama, which can present a high rate of mortality or recurrence of infection.