Etiolofia, epidemiologia e prognóstico das pneumonias associadas à ventilação mecânica em um hospital de ensino, com ênfase no estudo molecular e virulência de Staphylococcus aureus

Ventilator associated pneumonia (VAP) is the first cause of hospital acquired infections in patients in Intensive Care Units (ICU). The most frequent infectious agents isolated in VAP are Staphylococcus aureus, Pseudomonas aeruginosa and Acinetobacter baumannii, which vary according to the hospital. S. aureus methicillin resistant (MRSA) is frequently found in hospital environment, additionally this specie carry several virulence factors responsible to tissue invasion. Thereby, the aim of this work was verify the influence of host factors as well as the microbiologic factors in pneumonia outcome with emphasis in S. aureus genetic study. The study design was a cohort study including patients in the first 48 hours of mechanical ventilation and followed up twice a week for up to 8 weeks. More profound analysis was conducted for S. aureus isolates accessing the resistance profile, clonal characteristics by PFGE, sequence type by MLST, virulence by PCR, protein A and alpha toxin expressions by Western Blot, HPLC for PSM expressions. S. aureus was the most isolated specie in ICU and 66% of the isolates were causing respiratory infections. The frequency of MRSA in our ICU was 43% and the SCCmec types were I (4%), II (78%) e IV (17%). The most frequent virulence factors were icaA, hla e hld. The clonal profile of strains isolated from VAP showed a variety of strains not clustered. The most frequent sequence types in this study were ST105, ST5 and ST398. Independent risk factors for S. aureus VAP were PSMbeta 2 production, the presence of sea gene and solid cancer, while the presence of hlb and sea genes were associated to death. Trauma was the only predictor factor associated to VAP. Regarded to the stratification according to pathogen type, we found that trauma was a risk factor to S. aureus VAP and also for Enterobacteriacea, which also included belonging to female gender and presenting central nervous system disease. Age and steroids usage ...Pneumonia associada a ventilação mecânica (PAV) ocorre em pacientes em unidades de tratamento intensivo (UTI) com grande frequência sendo ocupando o primeiro lugar dentre infecções adquirida em sistemas de saúde. Os agentes mais frequentes isolados de PAV são Staphylococcus aureus, Pseudomonas aeruginosa e Acinetobacter baumannii, os quais variam em frequência de acordo com o centro de estudo. A resistência a oxacilina (MRSA - Methicillin Resistant S. aureus) é amplamente disseminada em hospitais, além dessa espécie carrear diversos fatores de virulência. Dessa forma esse trabalho teve como principal objetivo verificar a influência dos fatores do hospedeiro bem como fatores microbiológicos no desfecho pneumonia com ênfase no estudo genético de S. aureus. Assim foi realizado uma coorte prospectiva de pacientes nas primeiras 48 horas da ventilação mecânica. Foram realizadas duas visitas semanais por até oito semanas para a coleta de aspirado traqueal e dados clínicos. Nos isolados de S. aureus foi traçado o perfil de resistência, clonal por PFGE, tipo sequencial por MLST, virulência, expressão de proteína A e alfa toxina por Western Blot, caracterização e quantificação de PMSs. S. aureus foi a espécie mais isolada na UTI onde 66% desses isolados participaram de eventos infecciosos do sistema respiratório, seguido por Pseudomonas spp. e Acinetobacter spp. MRSA foi isolado numa frequência de 43% classificados como SCCmec tipos I (4%), II (78%) e IV (17%), sendo que 45% desses foram isolados de pacientes com PAV. Os fatores de virulência mais frequentes foram icaA, hla e hld. A análise por PFGE das amostras de pacientes com PAV revelou a presença de grande diversidade clonal. Os tipos sequenciais mais frequentes foram ST105, ST5 e ST398. Fatores de risco independentes para o desfecho PAV por S. aureus foram a produção de PSMbeta 2, gene sea e presença de neoplasia sólida, enquanto os genes hlb e sea estavam...Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Determinação da virulência e da resistência antimicrobiana em Staphylococcus spp. isolados de pacientes do Serviço de Dermatologia do Hospital das Clínicas da Faculdade de Medicina de Botucatu, SP

Staphylococcus aureus resistentes a meticilina (MRSA) emergiram logo após a introdução desse fármaco para tratamento de infecções hospitalares. A emergência da resistência a meticilina em cepas de Staphylococcus aureus na comunidade (CAMRSA) instiga a pesquisa de novos tratamentos e dos mecanismos de virulência relacionados a essas cepas. Indivíduos que não apresentavam fatores de risco tradicionais para aquisição de MRSA eram gravemente afetados por cepas de CAMRSA que geralmente apresentam-se mais virulentas. O objetivo desse trabalho foi determinar a ocorrência de Staphylococcus spp. e os fatores de risco para aquisição de MRSA como causa de infecções de pele e/ou de tecidos moles. Durante o período de estudo foram atendidos 127 pacientes com diagnóstico de infecções agudas de pele, sendo que 19 (14,9%) pacientes apresentaram cultura bacteriológica negativa e 108 (85,1%) apresentaram cultura positiva para Staphylococcus spp., isolando-se 116 amostras. Dessas 116 amostras, 66 (56,9%) foram identificadas como S. aureus e 50 (43,1%) como Estafilococos coagulase-negativa (ECN). O gene de resistência a meticilina foi detectado em 26 (21%) amostras, sendo sete (26,9%) em S. aureus e 19 (73,1%) em ECN. A resistência fenotípica para os discos de cefoxitina e oxacilina foi detectada em seis (85,7%) das amostras de S. aureus positivas para o gene mecA e, com relação aos ECN, 10 (52,6%) mostraram-se resistentes à oxacilina e somente cinco (26,3%) amostras mostraram-se resistentes para o disco de cefoxitina. Das 7 amostras de S. aureus positivas para o gene mecA 1 (14,2%) foi do tipo Ia, 3 (42,9%) do tipo II e 3 (42,9%) do tipo IV. Para os ECN foram encontrados 2 (10,5%) do tipo I e II cada, 3 (15,8%) do tipo III, 5 (26,4%) do tipo IV e 7 (36,8%) não foram tipáveis. O gene da PVL foi detectado em 15,1% das amostras de S. aureus. Os fatores de risco encontrados...The emergency of methicillin resistant Staphylococcus aureus strains in the community (CA-MRSA), lead to the search of new options of treatment and the virulence factors regarded to them. Individuals without the traditional risk factors for acquisition of MRSA were severely affected CA-MRSA strains, usually more virulent than health-care associated strains (HA-MRSA). The aim of this work was determinate the Staphylococcus spp. occurrence and the risk factors for MRSA acquisition as the main cause of skin and soft tissue infections. During the study period 127 patients were attended and diagnosed as acute skin infections, and 19 (14.9%) of the patients had negative bacterial culture and 108 (85.1%) had positive culture for Staphylococcus spp. and from that 116 samples were recovered. From these 116 samples, 66 (56.9%) were S. aureus and 50 (43.1%) were CoNS (coagulase-negative Staphylococcus). The methicillin resistance gene mecA was detected in 26 (21%) from the strains where 7 (26.9%) were S. aureus and 19 (73.1%) were CoNS. The phenotypic resistance for the cefoxitin and oxacillin discs was detected in 6 (85.7%) of S. aureus samples and, regarded to the CoNS samples 10 (52.6%) were resistant to the oxacillin disc and just 5 (26.3%) samples were resistant for the cefoxitin disk. From 7 S. aureus samples mecA positive 1 (14.2%) was type Ia, 3 (42.9%) type II and 3 (42.9%) type IV. For the CoNS isolated, 2 (10.5%) were tipe I and II for each one, 3 (15.8%) type III, 5 (26.4%) type IV and 7 (36.8%) were not able to type. The PVL gene was detected in 10 (15.1%) on S. aureus samples. The risk factors attributed to the MRSA acquisition on this study were the previous ciprofloxacin intake [OR: 8.75 (1.59 – 48.29) p= 0.01] and work in the health care settings [OR: 17.5 (1.22 – 250.36) p= 0.04]Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Systemic CA-MRSA infection following trauma during soccer match in inner Brazil: Clinical and molecular characterization

Even though community-acquired methicillin resistant Staphylococcus aureus (CA-MRSA) was described a decade ago, reports from Brazil are scarce and cases occurred in large urban centers. We report MRSA sepsis in a 16-year-old male from a small town and who had no history of exposure to healthcare or recent travel. After trauma during a soccer match, he presented swelling in the right thigh, which evolved in a month to cellulitis complicated by local abscess, orchitis and pneumonia. The patient presented severe sepsis, with fever and respiratory failure. Laboratory findings included blood leukocyte counts above 40,000/mm3 and thrombocytopenia. He was submitted to mechanical ventilation and therapy with vancomycin and imipenem. He had a slow but favorable response to therapy and was discharged after six weeks of hospitalization. MRSA grew from blood cultures and respiratory aspirates obtained before antimicrobial therapy. The isolate belonged to sequence type 5, spa type t311, harbored SCCmec type IV and genes for Panton-Valentine leukocidin and Enterotoxin A. The pulsed-field gel electrophoresis pattern was distinct from North American classic CA-MRSA clones. However, the sequence type and the spa type revealed that the clone belong to the same clonal complex isolated in Argentina. This is the first CA-MRSA infection reported in that region, with significant epidemiologic and clinical implications. © 2013 Elsevier Inc

A Study on the Epidemiological-Molecular Role of <i>Staphylococcus aureus</i> Strains in the Development of Ventilator-Associated Pneumonia in a Tertiary Hospital in Brazil

This study aimed to explore the molecular epidemiology of Staphylococcus aureus isolated from patients on mechanical ventilation and the participation of virulence factors in the development of ventilator-associated pneumonia (VAP). A prospective cohort study was conducted on patients under mechanical ventilation, with periodic visits for the collection of tracheal aspirates and clinical data. The S. aureus isolates were analyzed regarding resistance profile, virulence, expression of protein A and alpha-toxin using Western blot, clonal profile using PFGE, sequence type using MLST, and characterization and quantification of phenol-soluble modulins. Among the 270 patients in the study, 51 S. aureus strains were isolated from 47 patients. The incidence density of S. aureus and MRSA VAP was 2.35/1000 and 1.96/1000 ventilator days, respectively; of these, 45% (n = 5) were resistant to oxacillin, with 100% (n = 5) harboring SCCmec types II and IV. The most frequent among the tested virulence factors were icaA, hla, and hld. The clonal profile showed a predominance of sequence types originating from the community. Risk factors for VAP were the presence of solid tumors and the sea gene. In conclusion, patient-related risk factors, together with microbiological factors, are involved in the development of S. aureus VAP, which is caused by the patient’s own strains