Browsing tag: GBS

Zakażenia okołoporodowe o etiologii Streptococcus agalactiae

Perinatal infections caused by Streptococcus agalactiae
M. Bigos, M. Łysakowska, M. Wasiela
1. Wstęp. 2. Czynniki zjadliwości S. agalactiae. 3. Epidemiologia zakażeń S. agalactiae. 4. Chorobotwórczość S. agalactiae. 5. Lekowrażliwość szczepów S. agalactiae. 6. Diagnostyka nosicielstwa GBS. 7. Okołoporodowa profilaktyka antybiotykowa. 8. Immunoprofilaktyka zakażeń GBS. 9. Uwagi końcowe
Abstract: Streptococcus agalactiae are Gram-positive β-haemolytic bacteria belonging to group B streptococci (GBS), according to Rebecca Lancefield’s classification. They are commensals that colonize the distal parts of gastrointestinal, urinary, and genital tracts of healthy people. An increasing level of the pregnant women colonization by GBS was noted in the last decade. This raises a really high concern over the risk of severe perinatal infections among newborns since GBS are easily transmitted from mother being a S. agalactiae carrier to her child during delivery. Pneumonia, meningitis, bacteraemia, and sepsis are the most serious consequences of GBS infections in newborns. Moreover, the mortality rate among neonates infected with S. agalactiae reaches 20%. The microbiological screening for the GBS carriage among women being in 35–37 weeks of pregnancy are obligatory in Poland, starting from April, the 8 th, 2011. This paper is a review of current knowledge about GBS pathogenicity and epidemiology. The issues concerning the diagnostics of S. agalactiae carriage among pregnant women and the perinatal antibiotic prophylaxis are also presented.
1. Introduction. 2. S. agalactiae virulence factors. 3. Epidemiology of S. agalactiae infections. 4. Pathogenicity of S. agalactiae. 5. Drug susceptibility of S. agalactiae strains. 6. Diagnostics of GBS carriage. 7. Perinatal antibiotic prophylaxis. 8. Immunoprophylaxis of GBS infections. 9. Finald remarks

Budowa, regulacja i znaczenie czynników wirulencji szczepów Streptococcus agalactiae

The structure, regulation and the importance of S. agalactiae virulence factors
M. Łysakowska, M. Bigos, M. Wasiela

1. Wstęp. 2. Czynniki wirulencji szczepów S. agalactiae. 3. Toksyny GBS. 3.1. β-hemolizyna/cytolizyna. 3.2. Czynnik CAMP. 4. Czynniki umożliwiające unikanie odpowiedzi układu odporności. 4.1. Otoczka. 4.2. Dysmutaza nadtlenkowa. 4.3. Peptydaza C5a. 4.4. Proteinaza serynowa. 5. Oporność na peptydy przeciwbakteryjne. 5.1. Białka wiążące penicyliny. 5.2. Fimbrie. 5.3. Antygen b. 6. Adhezja i wnikanie. 6.1. Białka wiążące fibrinogen. 6.2. Białko wiążące lamininę. 6.3. Białka bogate w powtórzenia seryny. 6.4. Immunogenna adhezyna GBS. 6.5. Białko αC (APC). 6.6. Białko IagA. 6.7. Białko powierzchniowe Rib. 7. Inne czynniki uczestniczące w patogenezie GBS. 7.1. Hialuronidaza. 7.2. Regulator transportu metioniny (MtaR). 7.3. Zdolność do wykorzystania hemu. 8. Podsumowanie

Abstract: The course of the disease caused by S. agalactiae seems to depend greatly on the presence of its diverse virulence factors. To the most important virulence factors belong: capsule, C5a peptidase, which inhibits the action of neutrophils, α-C protein, laminin binding protein, and β hemolysin typical for invasive strains. Additionally, GBS strains may present FbsA protein which protects bacteria from opsonization and fagocytosis as well as takes part in adhesion. FbsB protein facilitates invasion to epithelial cells. Some GBS strains are able to produce surface protein inactivatng chemokine, CspA. S. agalactiae strains naturally inhabit genital and digestive tract, but in certain circumstances may be responsible for varions infections, both in neonates and adults. It suggests that these bacteria are able to adapt to diffwrent environments in infected individual and proper expression of virulence factors, in response to diverse niches, makes their survival possible. The goal of this work is to present the current knowledge concerning the virulence factors of S. agalactiae and, at the same time, possible reasons why these pathogens are still causing life threatening infections, especially in neonates.

1. Introduction. 2. Virulence factors S. agalactiae strains. 3. GBS toxins. 3.1. β-haemolisin/cytolisin. 3.2. CAMP factor. 4. Factors make possible escape answer of immunity system. 4.1. Capsule. 4.2. Peroxide dysmutase. 4.3. C5a peptidase. 4.4. Serine peptidase. 5. Resistance to antibacterial peptides. 5.1. Penicilin binding proteins. 5.2. Fimbries. 5.3. Antigen b. 6. Adhesion and penetration. 6.1. Fibrinogen binding proteins. 6.2. Laminin binding proteins. 6.3. Serine reports wich proteins. 6.4. Immunogenic GBS adhesin. 6.5. αC (APC) protein. 6.6. IagA protein. 6.7. Surface Rib protein. 7. Other patogenic GBS factors. 7.1. Hialuronidase. 7.2. Metionine transport regulator (MtaR). 7.3. Heme use ability. 8. Summary

Mechanizmy wirulencji paciorkowców β-hemolizujących

Virulence mechanisms factors and pathogenic of β-hemolytic streptococci
K. Obszańska, I. Kern-Zdanowicz, I. Sitkiewicz

1. Wstęp. 2. Paciorkowce grupy A (GAS). 3. Charakterystyka paciorkowców grupy B. 3.1. Czynniki wirulencji GBS. 4. Charakterystyka grup C i G. 4.1. Czynniki wirulencji GCS/GGS. 5. Charakterystyka grupy anginosus. 6. Podsumowanie

Abstract: Streptococcus is a highly diverse genus of gram positive bacteria. They can be divided into different groups based on their phenotypic properties. Usually criteria include hemolysis (α, β or γ) or type of surface carbohydrate (Lancefield antigen). Classification often includes phylogenetic groups (divisions) such as pyogenic, anginosus (milleri), mitis/oralis, salivarius and bovis. β-hemolytic streptococci are usually classified as pyogenic and anginosus groups, while others (with α-hemolysis) are commonly called viridans streptococci.
Among over 40 streptococcal species, several cause infections in humans and animals. For several species changes of host range and severity of infections were observed. Over the last four decades multiple virulence factors produced by pathogenic streptococci responsible for infection dynamics were identified and characterized.

1. Introduction. 2. Group A streptococci. 3. The characteristis of group B streptococci. 3.1. GBS virulence factors. 4. The characteristis of group C and G. 4.1. Virulence factors of GCS/GBS. 5. Characteristis anginosus group. 6. Summary