Streptococcus agalactiae –Only species that carries the group B antigen. –Initially recognized...
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Transcript of Streptococcus agalactiae –Only species that carries the group B antigen. –Initially recognized...
Streptococcus agalactiae
–Only species that carries the group B antigen.
– Initially recognized to cause puerperal sepsis (childbed fever )• Now this is uncommon
–Septicemia, pneumonia, and meningitis in newborns
–Other infections (Box 23-3)
Streptococcus agalactiae• Physiology and Structure– Gram (+) streptococci– Facultative anaerobe– β –hemolytic (1-2% are nonhemolytic)– Classified by B antigen
Streptococcus agalactiae• Epidemiology– Site of colonization:• Lower gastrointestinal tract• Genitourinary tract
– 10% to 30% of pregnant women are carriers.
– 60% of infants born to colonized mothers become infected with mothers’ organisms.• This can lead to pneumonia, bacteremia,
and meningitis
Streptococcus agalactiae• Epidemiology cont.– Infections in men and non-pregnant
women:• Primarily skin and soft-tissue• Bacteremia• Urosepsis (UTI with bacteremia)• Pneumonia
Streptococcus agalactiae• Epidemiology cont.– Conditions that predispose disease in
adults:• Diabetes mellitus• Cancer• Alcoholism
Streptococcus agalactiae• Clinical Diseases – Early-Onset Neonatal Disease• Disease acquired in utero or at birth,
symptoms appear within the first week of life.• Diseases:
– Bactermia– Pneumonia– Meningitis
• Pulmonary problems observed in most infants• Meningeal involvement may be non-
apparent at first– CSF examination is a must
Streptococcus agalactiae• 5% mortality rate• 15% to 30% of meningitis survivors have
neurological problems including:– Blindness– Deafness– Severe mental retardation
– Late-Onset (1 week to 3 months)• Source of disease:
– Mother– Other infants
• Bacteremia with meningitis
Streptococcus agalactiae• Clinical Diseases cont.– Pregnant women – UTI’s– Infections in Men and Non-pregnant
women• Generally older and/or compromised
immunity• Common infections
– Bacteremia – Pneumonia– Bone and joint infections– Skin and soft-tissue infections
• Mortality is higher in this group 15% to 32%.
Streptococcus agalactiae• Diagnosis– Culturing– Antigen Detection– DNA (PCR) test
• Treatment– Penicillin G– Pregnant women are give IV 4 hours
before delivery
Viridans Streptococci• Viridans– Heterogeneous collection of α-
hemolytic and nonhemolytic streptococci
– Name• Viridis is Latin for “green”
– 20 species identified and placed in 6 groups• Table 23-5
– Viridans cultures:• Require complex media• Supplemented with blood products• Incubation in 5% to 10% CO2
Viridans Streptococci• Viridans– Colonization• Oropharynx• Gastrointestinal tract• Genitourinary tract• Rarely found on skin
– Sebum is toxic to viridans
– Common infections• Dental caries• Subacute endocarditis
– http://heart.healthcentersonline.com/infectionsinjuries/endocarditis.cfm