Involvement of lipid microdomains in human endothelial cells infected by Streptococcus agalactiae type III belonging to the hypervirulent ST-17

BACKGROUND Streptococcus agalactiae capsular type III strains are a leading cause of invasive neonatal infections. Many pathogens have developed mechanisms to escape from host defense response using the host membrane microdomain machinery. Lipid rafts play an important role in a variety of cellular functions and the benefit provided by interaction with lipid rafts can vary from one pathogen to another. OBJECTIVES This study aims to evaluate the involvement of membrane microdomains during infection of human endothelial cell by S. agalactiae. METHODS The effects of cholesterol depletion and PI3K/AKT signaling pathway activation during S. agalactiae-human umbilical vein endothelial cells (HUVEC) interaction were analysed by pre-treatment with methyl-β-cyclodextrin (MβCD) or LY294002 inhibitors, immunofluorescence and immunoblot analysis. The involvement of lipid rafts was analysed by colocalisation of bacteria with flotillin-1 and caveolin-1 using fluorescence confocal microscopy. FINDINGS In this work, we demonstrated the importance of the integrity of lipid rafts microdomains and activation of PI3K/Akt pathway during invasion of S. agalactiae strain to HUVEC cells. Our results suggest the involvement of flotillin-1 and caveolin-1 during the invasion of S. agalactiae strain in HUVEC cells. CONCLUSIONS The collection of our results suggests that lipid microdomain affects the interaction of S. agalactiae type III belonging to the hypervirulent ST-17 with HUVEC cells through PI3K/Akt signaling pathway.

Isolation and identification of main mastitis pathogens in Mexico / Isolação e identificação dos micróbios patogênicos principais da mastite em México

The present work is a large epidemiological study aiming to detect the prevalence of subclinical mastitis and to investigate the major udder pathogens in Jalisco State, western Mexico. For this purpose, 2205 dairy cows, representing 33 Mexican dairy herds, were involved. Of 2205 cows, 752 mastitic animals were diagnosed and only 2,979 milk samples could be obtained for further investigation. All 2979 milk samples were subjected to California Mastitis Test (CMT) to differentiate clinical cases from subclinical ones where 1996 samples (67 %) reacted positively. Of these, 1087 samples (54.5%) came from cows suffering from clinical cases of mastitis. Bacteriological identification of the causative agents revealed the presence of a major group of pathogens including the Coagulase negative staphylococci (CNS), S.aureus, S.agalactiae, Corynebacterium spp. and Coliform bacteria which were detected in 464 (15.6%), 175 (5.9%), 200 (6.8%), 417 (14%) and 123 (4.1%) of the 2927 investigated quarters, 295 (15.4%), 118 (15.7%), 111 (14.8%), 227 (30.2%) and 109 (14.5%) of the 752 examined cows and in 33 (100%), 22 (66.7%), 19 (57.6%), 30 (90.1%) and 27 (81.8%) of the 33 herds involved, respectively. Other pathogens could be detected in the investigated milk samples such as S. dysgalactiae (0.4%), S.uberis (0.37%), Bacillus spp. (1%), Nocardia spp. (0.6%) und Candida spp. (0.1%). Meanwhile, others were present in a negligible ratio; including the Aerococcus viridans, and Enterococcus spp., Lactococcus lactis, S. bovis.

O trabalho atual é um estudo epidemiológico que objetiva detectar a predominância da mastite subclínica e investigar os micróbios patogênicos principais do úbere no México ocidental. Com esta finalidade, foram utilizadas 2205 vacas leiteiras, representando 33 rebanhos de leiteiras mexicanas. Além dessas 2205 vacas, 752 animais com mastite foram diagnosticados, considerando-se que somente 2979 amostras do leite poderiam ser obtidas para a posterior investigação. Todas as 2979 amostras do leite foram submetidas ao teste da mastite de Califórnia (CMT) para diferenciar casos clínicos dos subclínicos, visto que 1996 amostras (67%) reagiram positivamente. Além dessas, 1087 amostras (54.5%) vieram das vacas que sofrem de casos clínicos de mastite. A identificação bacteriológica dos agentes causais revelou a presença dos Staphylococcus negativos para coagulase (CNS), S. aureus, S. agalactiae, outros spp. Streptococcal, Corynebacterium spp., e as bactérias de coliformes foram detectadas em 464 (15.6%), 175 (5.9%), 200 (6.8%), 109 (3.9%), 417 (14%) e em 123 (4.1%) dos 2927 quartos investigados; em 295 (15.4%), 118 (15.7%), 111 (14.8%), 95 (12.6%), 227 (30.2%) e em 109 (14.5%) das 752 vacas examinadas e, finalmente, em 33 (100%), 22 (66.7%), 19 (57.6%), 30 (90.1%), 30 (90.1%) e em 27 (81.8%) dos 33 rebanhos envolvidos, respectivamente.

A Case of Streptococcus Agalactiae Pneumonia In An Adult Diabetic Man / 결핵

Despite significant advances in obstetric and pediatric health care, Streptococcus agalactiae(Lancefield group B β-hemolytic Streptococcus, GBS) remains one 91 the most prevalent and devastating pathogens in peripartum women and their newborn infants. It may cause urinary tract infection, chorioamnionitis and endometritis, bacteremia, and cesarean wound infection in the peripartum period. It was Pasteur who first identified microbes in the blood and lorchia of septic women. After that, in 1938 the isolation of S. agalactiae from three mortally ill women was reported, thereby implicating it as another cause of puerperal sepsis. S. agalactiae is now one of the most common causes of neonatal sepsis and meningitis in the United States. However, in Korea there have been only twenty-three cases of neonatal meningitis and/or sepsis due to group B β-hemolytic streptococcus reported. Recent studies have noted other serious infections in adults, including bacteremia, pneumonia, cellulitis, osteomyelitis, meningitis, and endocarditis. In Korean adults no case of pneumonia due to S. agalactiae has been reported till now. As minimal inhibitory concentration of penicillin was reported to be higher for S. agalactiae than for S. pyogenes, minimal inhibitory concentration of penicillin for S. agalactiae should be tested. Herein we describe the course of a case of S. agalactiae pneumonia and bacteremia in a 74-year-old diabetic man, and we review the literatures.