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

Viridans Streptococci• Viridans– Common infections cont.• Suppurative intraabdominal infections

– Prevention and Control • Susceptible to Penicillin, (most strains) • Moderately and highly resistant strains

have become more common