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1.
Rev Argent Microbiol ; 55(3): 240-245, 2023.
Artigo em Espanhol | MEDLINE | ID: mdl-36935274

RESUMO

Pneumococcal peritonitis represents a small subset of patients suffering from invasive pneumococcal disease (IPD). We describe 5 cases of primary peritonitis documented in the pediatric hospital over 15 years (2005-2020) of IPD surveillance. The patients, 3girls and 2boys with a mean age of 5 years, experienced peritoneal signs and symptoms; 3of them suffered from nephrotic syndrome. Based on the local resistance profiles, all isolates were sensitive to beta-lactams, one strain showed resistance to cotrimoxazole and tetracycline while another strain, to cotrimoxazole only. Serotypes found in 4/5 strains (one was non-viable) were: 1, 19F, 15C and 23A. Children were treated with third-generation cephalosporins or ampicillin, gentamicin and metronidazole and all of them evolved favorably. Pneumococcal etiology should be included in the differential diagnosis of acute abdominal pain in children. Our study aims to contribute to the knowledge of this condition and to the local epidemiology of IPD.


Assuntos
Peritonite , Infecções Pneumocócicas , Criança , Humanos , Lactente , Pré-Escolar , Combinação Trimetoprima e Sulfametoxazol , Argentina/epidemiologia , Hospitais Pediátricos , Streptococcus pneumoniae , Infecções Pneumocócicas/tratamento farmacológico , Peritonite/etiologia , Vacinas Pneumocócicas , Sorotipagem
2.
Rev Argent Microbiol ; 54(4): 335-343, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36266147

RESUMO

The aim of this review is to present an update on the susceptibility of viridans group streptococci (VGS) to ß-lactam antimicrobials, with emphasis on the Argentinean scenario. VGS are a heterogeneous group including five groups of species, each one exhibiting peculiar susceptibility patterns to penicillin (PEN). Species of the Streptococcus mitis group are frequently nonsusceptible to PEN. PEN resistance is associated with changes in PEN-binding proteins. In Argentina, one to two thirds of VGS are nonsusceptible to PEN. Third generation cephalosporins and carbapenems are currently more effective in vitro than PEN against VGS. Mortality was associated to nonsusceptibility to PEN in at least two studies involving patients with bacteremia caused by VGS. Treatment of endocarditis due to VGS should be adjusted/to the PEN susceptibility of the isolates. Vancomycin may be an alternative choice for treating endocarditis caused by PEN-resistant isolates (MIC≥4µg/ml).


Assuntos
Endocardite , Infecções Estreptocócicas , Humanos , Testes de Sensibilidade Microbiana , Infecções Estreptocócicas/tratamento farmacológico , Estreptococos Viridans , Penicilinas , Monobactamas , beta-Lactamas/farmacologia , beta-Lactamas/uso terapêutico , Antibacterianos/farmacologia , Antibacterianos/uso terapêutico , Endocardite/tratamento farmacológico
3.
Rev Argent Microbiol ; 53(3): 220-224, 2021.
Artigo em Espanhol | MEDLINE | ID: mdl-33541757

RESUMO

Streptococcus pneumoniae is a rare cause of osteoarticular infections. We describe 5documented cases that occurred in 2005, 2009, 2011, 2015 and 2017 in patients admitted to the Pediatric Provincial Reference Hospital of Misiones. These cases corresponded to a 4-year-old boy and 4 girls aged 11, 10, 6 years and 4 months with a diagnosis of osteomyelitis of the scapula and humerus, arthritis of the hip, ankle and osteomyelitis of the distal fibula. All of them were in good general condition on admission and one of them was seropositive for human immunodeficiency virus. All the recovered isolates were susceptible to ß-lactams and only one isolate showed joint resistance to macrolides and tetracycline. Three isolates were serotyped, 2of which carried vaccine serotypes (19F and 7F). Despite its low frequency, the etiology of S.pneumoniae should be considered among the osteoarticular infections. Our findings enhance the role of the Bacteriology laboratory in the diagnosis by microbiological culture and contribute to documenting the epidemiological behavior of this pathogen.


Assuntos
Infecções Pneumocócicas , Antibacterianos/uso terapêutico , Argentina/epidemiologia , Criança , Pré-Escolar , Feminino , Hospitais Pediátricos , Humanos , Lactente , Masculino , Testes de Sensibilidade Microbiana , Infecções Pneumocócicas/diagnóstico , Infecções Pneumocócicas/tratamento farmacológico , Infecções Pneumocócicas/epidemiologia , Vacinas Pneumocócicas , Sorotipagem , Streptococcus pneumoniae
4.
Rev Argent Microbiol ; 53(3): 266-271, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33875295

RESUMO

Streptococcus pneumoniae is an important causal agent of pneumonia, meningitis, sepsis, bacteremia, and otitis media. Penicillin resistance rates in S. pneumoniae have remained stable in Argentina in the last years. In the late '90s more isolates with MIC of penicillin ≥2µg/ml were observed; however, their frequency has decreased in recent years. The phenotypic expression of penicillin resistance is due to a modification in penicillin-binding proteins associated with a mosaic structure in the coding genes. The expansion of successful resistant clones varies among the different regions and is influenced by the use of antibiotics, vaccines, particularly conjugated ones, as well as population density. Parenteral treatment with high doses of penicillin G continues to be effective for the treatment of pneumonia and bacteremia, oral aminopenicillins for otitis media and sinusitis and third generation cephalosporins for meningitis.


Assuntos
Infecções Pneumocócicas , Streptococcus pneumoniae , Antibacterianos/farmacologia , Antibacterianos/uso terapêutico , Argentina , Humanos , Testes de Sensibilidade Microbiana , Resistência às Penicilinas , Infecções Pneumocócicas/tratamento farmacológico , Streptococcus pneumoniae/genética , beta-Lactamas/farmacologia
5.
Rev Argent Microbiol ; 52(2): 101-106, 2020.
Artigo em Espanhol | MEDLINE | ID: mdl-31628000

RESUMO

During the periods 2000-2004 and 2014-2015, Neisseria meningitidis was investigated in men who have sex with men, 1143 and 544 respectively, who consulted in the sexually-transmitted disease program. Prevalence, serogroup distribution and susceptibility to antibiotics were determined. Pharyngeal, rectal and urethral swabs were cultivated on selective Thayer-Martin modified medium. The identification was performed by biochemical tests and mass spectrometry by MALDI-TOF. Serogroups B, C, W and Y were investigated by PCR in 85 isolates recovered from the pharynx belonging to the second period. MICs of penicillin, ceftriaxone, rifampicin, azithromycin and ciprofloxacin were determined for 66 and 102 isolates from periods 1 and 2 respectively, according to CLSI. The prevalence of N. meningitidis was 17.8% and 28.1%, in periods 1 and 2 respectively; the isolates were mainly recovered from the pharynx. The distribution of serogroups was B 31.5%; Y 7.6%; W 3.3% and 9.8% non-capsulated and the rest would belong to other serogroups. Isolates classified as intermediate to penicillin were 34.8% and 63.7% (first and second periods, respectively); moreover, 11.8% of the isolates from the second period were resistant. All isolates were susceptible to ceftriaxone, to ciprofloxacin (except 3 isolates with MIC values between 0.25 and 0.5µg/ml), 3% were resistant to rifampicin and 2% were not susceptible to azithromicin. The prevalence of N. meningitidis carriage in men who have sex with men was high with a high rate of penicillin non-susceptible isolates. B was the prevalent serogroup.


Assuntos
Homossexualidade Masculina , Infecções Meningocócicas/microbiologia , Neisseria meningitidis/isolamento & purificação , Antibacterianos/farmacologia , Antibacterianos/uso terapêutico , Humanos , Masculino , Infecções Meningocócicas/tratamento farmacológico , Infecções Meningocócicas/epidemiologia , Testes de Sensibilidade Microbiana , Neisseria meningitidis/classificação , Neisseria meningitidis/efeitos dos fármacos , Prevalência , Sorogrupo
6.
Rev Argent Microbiol ; 51(1): 26-31, 2019.
Artigo em Espanhol | MEDLINE | ID: mdl-29941157

RESUMO

Members of the viridans group streptococci (VGS) are the cause of local and invasive infections. Due to the severity of these infections and taking into account that reports regarding epidemiological aspects are scarce, the aims of this work were the identification and the study of the antibiotic susceptibility profiles of the isolates recovered from patients that were hospitalized in order to find out about the resistance level and the epidemiology of infections in which VGS are involved. A hundred and thirty two isolates identified as VGS were isolated at Hospital de Clínicas «José de San Martín¼ during the period 2011-2015. The identification was performed by biochemical test and mass spectrometry by Matrix Assisted Laser Desorption Ionization -Time of Flight Mass Spectrometry. Streptococcus anginosus group was prevalent (42%) followed by Streptococcus mitis group (33%). In the latter, isolates of Streptococcus pneumoniae were excluded. All the VGS isolates were susceptible to ertapenem, meropenem, linezolid and vancomycin; 25.8% were resistant (I+R) to penicillin, being prevalent in the S. mitis group. Regarding ceftriaxone and cefepime 96.9% of the isolates were susceptible. Only two isolates were resistant to levofloxacin, 27.2% to tetracycline and it was not found high level resistance to gentamycin (MIC range 0.5-32µg/ml). Resistance to erythromycin was 17.4% with no significant difference between M and MLS phenotypes. The most active antibiotics were in addition to ceftriaxone and cefepime, vancomycin, ertapenem, meropenem and linezolid. These results highlight the importance of the continuous surveillance of the infections caused by VGS in order to predict a correct antibiotic therapy.


Assuntos
Antibacterianos/farmacologia , Estreptococos Viridans/efeitos dos fármacos , Argentina , Farmacorresistência Bacteriana , Hospitalização , Hospitais de Ensino , Humanos , Testes de Sensibilidade Microbiana , Infecções Estreptocócicas/tratamento farmacológico , Infecções Estreptocócicas/microbiologia , Saúde da População Urbana , Estreptococos Viridans/isolamento & purificação
7.
Rev Argent Microbiol ; 51(2): 179-183, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30243525

RESUMO

Enterococci are intrinsically resistant to several antimicrobial classes and show a great ability to acquire new mechanisms of resistance. Resistance to ß-lactam antibiotics is a major concern because these drugs either alone or in combination are commonly used for the treatment of enterococcal infections. Ampicillin resistance, which is rare in Enterococcus faecalis, occurs in most of the hospital-associated Enterococcus faecium isolates. High-level resistance to ampicillin in E. faecium is mainly due to the enhanced production of PBP5 and/or by polymorphisms in the beta subunit of this protein. The dissemination of high-level ampicillin resistance can be the result of both clonal spread of strains with mutated pbp5 genes and horizontal gene transfer.


Assuntos
Enterococcus/efeitos dos fármacos , beta-Lactamas/farmacologia , Farmacorresistência Bacteriana , Infecções por Bactérias Gram-Positivas/tratamento farmacológico , Humanos , Lactobacillales , Testes de Sensibilidade Microbiana , beta-Lactamas/uso terapêutico
8.
Medicina (B Aires) ; 78(5): 311-314, 2018.
Artigo em Espanhol | MEDLINE | ID: mdl-30285923

RESUMO

It is erroneously believed that group A streptococci (GAS) are universally resistant to trimethoprim-sulfamethoxazole (TMS). This is mainly because media commonly used for in vitro determination of susceptibility to antibiotics contain thymidine, a nucleoside that antagonizes the antibiotic effect of TMS. The objective of this work was to determine EGA sensitivity to TMS in the presence and absence of thymidine. To this aim, 95 GAS isolates obtained from clinical tissues with i nvasive infections were analyzed. Susceptibility tests were performed by diffusion with TMS discs in Mueller Hinton agar supplemented either with 5% sheep blood or with 5% lysed equine blood (MH-LEB). Lysed equine blood contains thymidine phosphorylase, which degrades this nucleoside. Epsilometry (Etest) was used as gold standard. Quality controls with Enterococcus faecalis strain ATCC 29212 were satisfactory with both media. A 100% sensitivity to TMS was found in MH-SEL whereas 6 isolates (6.3%) resulted resistant in MH-SC; only one of them was found to have intermediate susceptibility by Etest (MIC > 1.5/28 υg/ml). The genetic determinants most frequently associated to TMS resistant EGA were not found in this isolate. Probably, if more accurate GAS-specific cut-off points were established for diffusion, the correlation with dilution methods or with the Etest could be improved, even employing MH-SB.


Assuntos
Antibacterianos/farmacologia , Streptococcus pyogenes/efeitos dos fármacos , Combinação Trimetoprima e Sulfametoxazol/farmacologia , Meios de Cultura , Humanos , Testes de Sensibilidade Microbiana , Reação em Cadeia da Polimerase , Infecções Estreptocócicas/microbiologia , Streptococcus pyogenes/genética , Streptococcus pyogenes/isolamento & purificação
9.
Rev Argent Microbiol ; 50(4): 431-435, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29548731

RESUMO

Group A (GAS), B (GBS), C (GCS) and G (GGS) ß-hemolytic streptococci are important human pathogens. They cause infections of different severity and frequency. Nowadays, after 70 years of use, penicillin is still universally active against GAS, GCS and GGS. However, therapeutic failures have been recorded in 2-28% of pharyngitis cases (median: 12%) attributable to different causes. By contrast, some GBS with reduced susceptibility to penicillin have been described, especially in Japan. In this group of bacteria, it is important to highlight that confirmation by reference methods is mandatory when decreased susceptibility to penicillin is suspected as well as checked for the detection of the mechanisms involved.


Assuntos
Streptococcus/efeitos dos fármacos , beta-Lactamas/farmacologia , Farmacorresistência Bacteriana , Humanos , Testes de Sensibilidade Microbiana
10.
Int J Med Microbiol ; 307(4-5): 191-199, 2017 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-28549830

RESUMO

Community-acquired methicillin resistant Staphylococcus aureus emerged as a worldwide health problem in the last few years. In Argentina, it is found in 70% of skin and skin structure infections in previously healthy adult patients and causes severe invasive diseases. The ST30-SCCmecIVc-spat019 clone is predominant in adult infections and has displaced the previously prevalent ST5-SCCmecIVa-spat311 clone in community settings. In the present work we compared the virulence of both clones in order to explain the displacement, and found that ST30-IVc is associated with invasive infections in adult patients from Argentina and possesses a different virulence-associated genes profile compared to ST5-IVa. A representative strain of ST30 lineage has a more aggressive behavior in animal models of infection and expresses higher level of Fibronectin binding protein A coding gene, which could enhance the bacterial invasion capacity.


Assuntos
Proteínas de Bactérias/genética , Staphylococcus aureus Resistente à Meticilina/genética , Fatores de Virulência/genética , Adesinas Bacterianas/genética , Adesinas Bacterianas/metabolismo , Animais , Argentina , Proteínas de Bactérias/metabolismo , Contagem de Colônia Microbiana , Infecção Hospitalar/microbiologia , Modelos Animais de Doenças , Feminino , Staphylococcus aureus Resistente à Meticilina/isolamento & purificação , Staphylococcus aureus Resistente à Meticilina/patogenicidade , Camundongos , Camundongos Endogâmicos BALB C , Estudos Multicêntricos como Assunto , Ratos , Ratos Wistar , Infecções Respiratórias/microbiologia , Infecções Cutâneas Estafilocócicas/microbiologia
11.
J Enzyme Inhib Med Chem ; 32(1): 203-207, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-28114831

RESUMO

The UDP-glucose pyrophosphorylase of Streptococcus pneumoniae (GalUSpn) is absolutely required for the biosynthesis of capsular polysaccharide, the sine qua non virulence factor of pneumococcus. Since the eukaryotic enzymes are completely unrelated to their prokaryotic counterparts, we propose that the GalU enzyme is a critical target to fight the pneumococcal disease. A recombinant GalUSpn was overexpressed and purified. An enzymatic assay that is rapid, sensitive and easy to perform was developed. This assay was appropriate for screening chemical libraries for searching GalU inhibitors. This work represents a fundamental step in the exploration of novel antipneumococcal drugs.


Assuntos
Antibacterianos/farmacologia , Avaliação Pré-Clínica de Medicamentos/métodos , Inibidores Enzimáticos/farmacologia , Streptococcus pneumoniae/efeitos dos fármacos , Streptococcus pneumoniae/enzimologia , UTP-Glucose-1-Fosfato Uridililtransferase/antagonistas & inibidores , Antibacterianos/síntese química , Antibacterianos/química , Relação Dose-Resposta a Droga , Inibidores Enzimáticos/síntese química , Inibidores Enzimáticos/química , Testes de Sensibilidade Microbiana , Estrutura Molecular , Proteínas Recombinantes/metabolismo , Relação Estrutura-Atividade , UTP-Glucose-1-Fosfato Uridililtransferase/metabolismo
12.
Rev Argent Microbiol ; 49(2): 142-145, 2017.
Artigo em Espanhol | MEDLINE | ID: mdl-28416258

RESUMO

The role of Streptococcus pneumoniae as a causative agent of skin and soft tissue infections (SSTI) is unusual and its clinical interpretation is difficult. We describe here three cases of SSTI due to S. pneumoniae in patients admitted to the Provincial Pediatric Hospital of Misiones, Argentina that were detected during 10 years of invasive disease (ID) surveillance documented in 2010, 2011 and 2015. These cases involved two girls aged 8 and 7 months old, and a two-year-old male child with diagnoses of gluteal abscess, preseptal cellulites and pyoderma respectively. All the patients were eutrophic and in good general condition on admission; one of them was seropositive for HIV. Antimicrobial susceptibility and serotypes were framed within the local epidemiology of invasive pneumococcal disease. Despite its low frequency, S. pneumoniae as an etiological agent of SSTI must be considered. Our findings revalue the role of the diagnostic laboratory and contribute to document the behavior of this pathogen.


Assuntos
Infecções Pneumocócicas , Infecções dos Tecidos Moles , Streptococcus pneumoniae , Argentina , Pré-Escolar , Feminino , Humanos , Lactente , Masculino , Infecções Pneumocócicas/diagnóstico , Infecções Pneumocócicas/tratamento farmacológico , Sorotipagem , Infecções dos Tecidos Moles/diagnóstico , Infecções dos Tecidos Moles/tratamento farmacológico , Streptococcus pneumoniae/isolamento & purificação
13.
Rev Argent Microbiol ; 49(2): 139-141, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28325626

RESUMO

The aim of this report is to describe a rare case of necrotizing pneumonia due to group B Streptococcus serotype III in a relatively young male adult (48 years old) suffering from diabetes. The organism was isolated from his pleural fluid and was only resistant to tetracycline. The patient first received ceftazidime (2g/8h i.v.)+clindamycin (300mg/8h) for 18 days and then he was discharged home and orally treated with amoxicillin clavulanic acid (1g/12h) for 23 days with an uneventful evolution. As in the cases of invasive infection by Streptococcus pyogenes, clindamycin could prevent streptococcal toxic shock syndrome.


Assuntos
Complicações do Diabetes , Pneumonia Necrosante , Infecções Estreptocócicas , Clindamicina , Diabetes Mellitus , Humanos , Masculino , Pessoa de Meia-Idade , Pneumonia Necrosante/complicações , Pneumonia Necrosante/diagnóstico , Pneumonia Necrosante/microbiologia , Infecções Estreptocócicas/complicações , Infecções Estreptocócicas/diagnóstico , Streptococcus pyogenes
14.
Ann Clin Microbiol Antimicrob ; 15: 15, 2016 Mar 08.
Artigo em Inglês | MEDLINE | ID: mdl-26956508

RESUMO

BACKGROUND: Tigecycline (TIG) is an antibiotic belonging to the glycylcyclines class and appears to be a good choice to fight infections caused by Staphylococcus aureus. To date, TIG exhibits good activity against this microorganism. The aim of this work was to obtain in vitro mutants of S. aureus resistant to TIG and evaluate possible changes in their susceptibility patterns to other antibiotics. RESULTS: Two mutants of S. aureus resistant to TIG (MIC = 16 µg/mL) were selected in vitro from clinical isolates of methicillin-resistant S. aureus. In both mutants, corresponding to different lineage (ST5 and ST239), an increase of efflux activity against TIG was detected. One mutant also showed a reduced susceptibility to vancomycin, corresponding to the VISA phenotype (MIC = 4 µg/mL), with a loss of functionality of the agr locus. The emergence of the VISA phenotype was accompanied by an increase in oxacillin and cefoxitin MICs. CONCLUSIONS: This study demonstrates that, under selective pressure, the increase of efflux activity in S. aureus is one of the mechanisms that may be involved in the emergence of tigecycline resistance. The emergence of this phenotype may eventually be associated to changes in susceptibility to other antibiotics such oxacillin and vancomycin.


Assuntos
Antibacterianos/farmacologia , Minociclina/análogos & derivados , Infecções Estafilocócicas/microbiologia , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/genética , Vancomicina/farmacologia , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Farmacorresistência Bacteriana , Humanos , Testes de Sensibilidade Microbiana , Minociclina/farmacologia , Mutação/efeitos dos fármacos , Staphylococcus aureus/metabolismo , Tigeciclina
15.
Rev Argent Microbiol ; 47(1): 50-3, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25681265

RESUMO

Community-acquired methicillin-resistant Staphylococcus aureus is the first cause of skin and soft tissue infections, but can also produce severe diseases such as bacteremia, osteomyelitis and necrotizing pneumonia. Some S. aureus lineages have been described in cases of necrotizing pneumonia worldwide, usually in young, previously healthy patients. In this work, we describe a fatal case of necrotizing pneumonia due to community-acquired methicillin-resistant S. aureus clone ST30-SCCmecIVc-spat019-PVL positive in an immunocompetent adult patient.


Assuntos
Staphylococcus aureus Resistente à Meticilina , Pneumonia Bacteriana/microbiologia , Infecções Estafilocócicas/microbiologia , Argentina , Infecções Comunitárias Adquiridas/patologia , Evolução Fatal , Humanos , Masculino , Staphylococcus aureus Resistente à Meticilina/classificação , Pessoa de Meia-Idade , Necrose , Pneumonia Bacteriana/patologia , Infecções Estafilocócicas/patologia
16.
Microb Drug Resist ; 30(3): 109-117, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38133499

RESUMO

Staphylococcus aureus bacteremia (SAB) is one of the most common serious bacterial infections worldwide. In this study, we demonstrated changes in SAB epidemiology in an Argentinean University Hospital during an 8-year period (2009-2016). A total of 326 S. aureus clinical isolates were recovered in three periods: P1: 2009-2010, P2: 2012-2014, and P3: 2015-2016. Among these, 127 were methicillin-resistant S. aureus (MRSA) and were characterized by phenotypic and molecular methods. We hereby report a significant decline in multiple drug resistance among MRSA isolates associated with an increase in SCCmec IV between the three periods. A diversity of MRSA-IV clones (mainly ST30-MRSA-IV, ST5-MRSA-IV, and ST8-MRSA-IV) replaced between 2009 and 2016 the previous prevalent MRSA clone causing bloodstream infections at this hospital (ST5-MRSA-I). MRSA population structure continued to diversify between P2 and P3. Notably, ST8-MRSA-IV-t008 related to USA300 was first detected during P2, and ST8-MRSA-IV together with ST30-MRSA-IV related to the Southwest Pacific clone were the more prevalent MRSA genotypes circulating during P3.


Assuntos
Bacteriemia , Staphylococcus aureus Resistente à Meticilina , Infecções Estafilocócicas , Humanos , Staphylococcus aureus/genética , Staphylococcus aureus Resistente à Meticilina/genética , Argentina/epidemiologia , Hemocultura , Antibacterianos/farmacologia , Testes de Sensibilidade Microbiana , Infecções Estafilocócicas/tratamento farmacológico , Infecções Estafilocócicas/epidemiologia , Infecções Estafilocócicas/microbiologia , Hospitais Universitários , Bacteriemia/tratamento farmacológico , Bacteriemia/epidemiologia
17.
Antibiotics (Basel) ; 13(6)2024 Jun 13.
Artigo em Inglês | MEDLINE | ID: mdl-38927220

RESUMO

The mec-independent oxacillin non-susceptible S. aureus (MIONSA) strains represent a great clinical challenge, as they are not easily detected and can lead to treatment failure. However, the responsible molecular mechanisms are still very little understood. Here, we studied four clinical ST8-MSSA-t024 isolates recovered during the course of antibiotic treatment from a patient suffering successive episodes of bacteremia. The first isolates (SAMS1, SAMS2, and SAMS3) were susceptible to cefoxitin and oxacillin. The last one (SA2) was susceptible to cefoxitin, resistant to oxacillin, lacked mec genes, and had reduced susceptibility to teicoplanin. SA2 showed higher ß-lactamase activity than SAMS1. However, ß-lactamase hyperproduction could not be linked to oxacillin resistance as it was not inhibited by clavulanic acid, and no genetic changes that could account for its hyperproduction were found. Importantly, we hereby report the in vivo acquisition and coexistence of different adaptive mutations in genes associated with peptidoglycan synthesis (pbp2, rodA, stp1, yjbH, and yvqF/vraT), which is possibly related with the development of oxacillin resistance and reduced susceptibility to teicoplanin in SA2. Using three-dimensional models and PBP binding assays, we demonstrated the high contribution of the SA2 PBP2 Ala450Asp mutation to the observed oxacillin resistance phenotype. Our results should be considered as a warning for physicians and microbiologists in the region, as MIONSA detection and treatment represent an important clinical challenge.

18.
J Infect Dis ; 206(1): 81-90, 2012 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-22535996

RESUMO

Staphylococcus aureus protein A (SpA) plays a critical role in the induction of inflammation. This study was aimed to determine whether the number of short sequence repeats (SSRs) present in the polymorphic region modulates the inflammatory response induced by SpA. We demonstrated that there is a dose-response effect in the activation of interferon (IFN)-ß signaling in airway epithelial and immune cells, depending on the number of SSRs, which leads to differences in neutrophil recruitment. We also determined that a significant proportion of isolates from patients with chronic infections such as osteomyelitis and cystic fibrosis carry fewer SSRs than do isolates from patients with acute infections or healthy carriers and that there was an inverse correlation between the number of SSRs and the length of disease course. Given the importance of IFN signaling in eradication of S. aureus, loss of SSRs may represent an advantageous mechanism to adapt to and persist in the host.


Assuntos
Inflamação/genética , Infecções Estafilocócicas/microbiologia , Proteína Estafilocócica A/metabolismo , Adolescente , Adulto , Animais , Linhagem Celular , Criança , Pré-Escolar , Doença Crônica , Fibrose Cística/genética , Fibrose Cística/imunologia , Fibrose Cística/metabolismo , Fibrose Cística/microbiologia , Relação Dose-Resposta Imunológica , Humanos , Lactente , Inflamação/imunologia , Inflamação/metabolismo , Inflamação/microbiologia , Interferon beta/imunologia , Interferon beta/metabolismo , Camundongos , Camundongos Endogâmicos BALB C , Repetições de Microssatélites , Infiltração de Neutrófilos/genética , Infiltração de Neutrófilos/imunologia , Osteomielite/genética , Osteomielite/imunologia , Osteomielite/metabolismo , Osteomielite/microbiologia , Polimorfismo Genético , Mucosa Respiratória/imunologia , Mucosa Respiratória/microbiologia , Infecções Estafilocócicas/genética , Infecções Estafilocócicas/imunologia , Infecções Estafilocócicas/metabolismo , Proteína Estafilocócica A/genética , Proteína Estafilocócica A/imunologia , Staphylococcus aureus/genética , Staphylococcus aureus/metabolismo , Adulto Jovem
19.
Antibiotics (Basel) ; 12(2)2023 Feb 11.
Artigo em Inglês | MEDLINE | ID: mdl-36830286

RESUMO

Infections due to vancomycin-intermediate S. aureus (VISA) and heterogeneous VISA (hVISA) represent a serious concern due to their association with vancomycin treatment failure. However, the underlying molecular mechanism responsible for the hVISA/VISA phenotype is complex and not yet fully understood. We have previously characterized two ST100-MRSA-hVISA clinical isolates recovered before and after 40 days of vancomycin treatment (D1 and D2, respectively) and two in vitro VISA derivatives (D23C9 and D2P11), selected independently from D2 in the presence of vancomycin. This follow-up study was aimed at further characterizing these isogenic strains and obtaining their whole genome sequences to unravel changes associated with antibiotic resistance. It is interesting to note that none of these isogenic strains carry SNPs in the regulatory operons vraUTSR, walKR and/or graXRS. Nonetheless, genetic changes including SNPs, INDELs and IS256 genomic insertions/rearrangements were found both in in vivo and in vitro vancomycin-selected strains. Some were found in the downstream target genes of the aforementioned regulatory operons, which are involved in cell wall and phosphate metabolism, staphylococcal growth and biofilm formation. Some of the genetic changes reported herein have not been previously associated with vancomycin, daptomycin and/or oxacillin resistance in S. aureus.

20.
Microb Genom ; 9(5)2023 05.
Artigo em Inglês | MEDLINE | ID: mdl-37227244

RESUMO

Staphylococcus aureus remains one of the leading causes of infections worldwide and a common cause of bacteraemia. However, studies documenting the epidemiology of S. aureus in South America using genomics are scarce. We hereby report on the largest genomic epidemiology study to date of both methicillin-resistant S. aureus (MRSA) and methicillin-susceptible S. aureus (MSSA) in South America, conducted by the StaphNET-SA network. We characterised 404 genomes recovered from a prospective observational study of S. aureus bacteraemia in 58 hospitals from Argentina, Bolivia, Brazil, Paraguay and Uruguay between April and October 2019. We show that a minority of S. aureus isolates are phenotypically multi-drug resistant (5.2%), but more than a quarter are resistant to macrolide-lincosamide-streptogramin B (MLSb). MSSA were more genetically diverse than MRSA. Lower rates of associated antimicrobial resistance in community-associated(CA)-MRSA versus hospital-associated (HA)-MRSA were found in association with three S. aureus genotypes dominating the MRSA population: CC30-MRSA-IVc-t019-lukS/F-PV+, CC5-MRSA-IV-t002-lukS/F-PV- and CC8-MRSA-IVc-t008-lukS/F-PV+-COMER+. These are historically from a CA origin, carry on average fewer antimicrobial resistance determinants, and often lack key virulence genes. Surprisingly, CC398-MSSA-t1451-lukS/F-PV- related to the CC398 human-associated lineage is widely disseminated throughout the region, and is described here for the first time as the most prevalent MSSA lineage in South America. Moreover, CC398 strains carrying ermT (largely responsible for the MLSb resistance rates of MSSA strains: inducible iMLSb phenotype) and sh_fabI (related to triclosan resistance) were recovered from both CA and HA origin. The frequency of MRSA and MSSA lineages differed between countries but the most prevalent S. aureus genotypes are high-risk clones widely distributed in the South American region without a clear country-specific phylogeographical structure. Therefore, our findings underline the need for continuous genomic surveillance by regional networks such as StaphNET-SA. This article contains data hosted by Microreact.


Assuntos
Bacteriemia , Staphylococcus aureus Resistente à Meticilina , Sepse , Infecções Estafilocócicas , Humanos , Staphylococcus aureus/genética , Infecções Estafilocócicas/epidemiologia , Staphylococcus aureus Resistente à Meticilina/genética , Bacteriemia/epidemiologia , Genômica , Brasil
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