Apoptose induzida por estreptococos do grupo B em células epiteliais respiratórias A549 / Apoptosis induced by group B streptococci in respiratory epithelial cells A549

Streptococcus agalactiae, ou Streptococcus do grupo B (GBS), é um importante patógeno oportunista que causa pneumonia, sepse e meningite em recém-nascidos e infecções em adultos imunocomprometidos. O pulmão aparentemente é o portal de entrada para o EGB na corrente sanguínea o que pode evoluir para uma septicemia. Os mecanismos de virulência relevantes envolve a habilidade do EGB em penetrar e sobreviver intracelularmente em células hospedeiras. Neste trabalho, foram analisados os mecanismos moleculares da apoptose epitelial induzida pelo EGB, e a produção de óxido nítrico (NO) e espécies reativas de oxigênio (ROS) em células epiteliais respiratórias A549 durante a infecção por EGB. Todas as amostras de EGB exibiram a capacidade de aderir e invadir células A549. A sobrevivência intracelular do EGB em células A549 ocorreu durante 24 h de incubação sem replicação do patógeno. No entanto, a amsotra 88641-V isolada de vagina não sobreviveu após 0,5 h de interação. O EGB promoveu a perda de viabilidade do epitélio durante a infecção. As alterações morfológicas em células A549 infectadas com o EGB incluem arredondamento celular, condensação nuclear, encolhimento celular e perda de contato célula-célula e célula-substrato. A dupla marcação AV/IP revelou que amostras de EGB sorotipo III induziram apoptose enquanto amostras do sorotipo V induziram morte celular semelhante a necrose em células A549. Caspase-3 foi ativada durante a apoptose induzida por EGB em células epiteliais. No entanto, a ativação de caspases-8 e -9 foi detectada apenas para a amostra 88641-V e as amostras EGB do sorotipo III, respectivamente. Experimentos comparativos de Immunoblotting revelaram que o EGB induziu um aumento da expressão Bim, uma proteína pró-apoptótica e diminuiu a expressão de Bcl-2 e Bcl-xL, proteínas anti-apoptóticas. As células A549 apresentaram perda de potencial de membrana mitocondrial Δψm e co-localização com o Bax...

Streptococcus agalactiae, or group B Streptococcus (GBS), is an important opportunistic pathogen that causes pneumonia, sepsis, and meningitis in neonates and severe diseases in immunocompromised adults. The lung is the apparent portal of entry for GBS into the bloodstream, after which septicemia may ensue. A relevant virulence mechanism involves the ability of GBS to penetrate and to survive intracellularly within these host cells. In this work, we analyzed the molecular mechanisms of GBS-induced epithelial apoptosis, and nitric oxide (NO) and reactive oxygen species (ROS) production by lung epithelial cell line A549 cells during infection with GBS. All GBS exhibited the ability to adhere and to invade A549 cells. The survival of GBS within A549 cells without replication was shown during 24 h incubation. However, the 88641-V strain isolated from vagina did not survive after 0.5 h of interaction. GBS promoted the loss of viability of the epithelium during infection. The morphological changes in A549 cells infected with GBS included cell rounding, nuclear condensation, cellular shrinkage and loss of cell-cell contact and cell-substrate. The double staining AV / IP revealed that GBS serotype III induced apoptosis while GBS serotype V induced like necrosis cell death in A549 cells. Caspase-3 was activated during GBS-induced endothelial apoptosis. However, activation of caspases-8 and -9 was detected only by GBS 88641-V and GBS-III, respectively. Comparative immunoblotting experiments revealed that GBS induced an increasing pro-apoptotic Bim expression and decreasing anti-apoptotic Bcl-2 and Bcl-XL expression. A549 cells exhibited loss of mitochondrial membrane potential Δψm with Bax colocalization...

The Comparative Analysis of Bacterial and Aseptic Meningitis in Neonates / 대한소아신경학회지

PURPOSE: This study was aimed to evaluate the clinical features of bacterial and aseptic meningitis in neonates. METHODS: Seventy seven neonates who diagnosed with meningitis at Inha University Hospital from June 1996 to August 2010 were enrolled in this study. The subjects were classified into either bacterial or aseptic meningitis and their medical records were retrospectively analyzed. RESULTS: Among the 77 cases, 18 cases were bacterial and 59 cases were aseptic. The main symptoms of both groups were fever, moaning in order. In bacterial meningitis, Group B streptococci (GBS) was the most common causative organism (12/18. 75%). In peripheral blood exam, patients with bacterial meningitis were more likely to show leukocytosis (WBC >20,000/mm3) and leukopenia (WBC <5,000/mm3) than those with aseptic meningitis. CRP was also significantly increased in the group of bacterial meningitis. In CSF analysis, 61.2% revealed pleocytosis more than 1,000/mm3 in bacterial meningitis and 8.5% did in aseptic meningitis. CSF glucose were <40 mg/dL in 72.2% of the group of bacterial meningitis and 35.6% of the group of aseptic meningitis. Mean CSF protein was 289.6+/-221.2 mg/dL in bacterial meningitis and 107.6+/-73.9 mg/dL in aseptic meningitis. Abnormal radiologic findings were found in 44.4% of bacterial meningitis and 8.4% of aseptic meningitis. The treatments were empirically initiated with ampicillin and cefotaxime in 60 cases, ampicillin and aminoglycosides in 12 cases. CONCLUSION: Although the clinical features of bacterial and aseptic meningitis are similar, peripheral blood and CSF exams revealed significant differences. Based on these differences, appropriate antibiotic treatment can be selected before the identification of causative agents.

A Study of Group B Streptococcal Infection in Korean Pregnant Women / 대한산부인과학회잡지

OBJECTIVE: To evaluate the degree of streptococcal colonization in Korean pregnant women. METHODS: The study comprised of 153 singleton pregnant women who visited Severance Hospital for delivery, and their neonates. Specimens for GBS culture were collected by a sterile cotton swab from lower vagina and cervix of pregnant women, and from ear canal and throat of neonates. They were first cultured for 48 hours in Todd-Hewitt broth and then subcultured onto Tryptose blood agar plates(Difco). Group B streptococci were confirmed by the presence of beta-hemolysis and a positive reaction with Phadebact group B Streptococci reagent(Karo Biodiagnostics AB, Huddinge, Sweden). RESULTS: The prevalence of positive cultures in pregnant women and neonates were 2.61%(4/153) and 0%(0/4), respectively. In the study population there was a case of suspicious group B streptococcual sepsis in an infant whose mother was colonized. CONCLUSIONS: In our study the GBS colonization rate in Korean pregnant women was significantly lower than that of other countries. The reason for this difference may be associated with a racial differences, or social factors such as socio-economic status or a life style.