Viridans Steptococci and

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Viridans Steptococci and Groups C and G
Streptococci
Piyarat rueangbut MD.
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microbiology species identification epidemiol
ogy pathogenicity clinical manifestations th
erapy
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Microbiology -Facultatively anaerobic ,
gram-positive cocci. -Not produce catalase or
coagulase on blood agar. -viridans? Latin word
viridis? green -Partial destruction of
erythrocytes with resultant green discoloration
on blood agar (a-hemolysis). -The organisms are
nonmotile and non-spore-forming. -Ferment
carbohydrates with acid but without gas
production.
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Species Identification -Multiple species of
a-hemolytic Streptococci. -Heterogenous group of
organism - the human oral viridans
streptococci
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Viridans streptococcus
Salivarius group -S.salivarius -S.vestibulalaris -
S.thermophilus
Mutans group -S.mutans -S.rattus -S.cricetus -S.ma
cacae -S.sobrinus -S.downii
Bovis group -S.bovis -S.equinus -S.alactolyticus
Mitis group -S.sanguis -S.parasanguis -S.gordoni -
S.oralis -S.mitis -S.pneumoniae
Anginosus group -S.anginosus -S.constellatus -S.in
termedis
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• Epidermology
• -Normal flora
• -URT , female genital tract , GI tract , oral
  cavity
• ?28 - flora from dental plaque.
• ?29 - gingival crevices.
• ?45 - the tongue.
• ?46 - saliva.
• In healthy person colonization resistance

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• Pathogenicity
• Low virulence.
• Not known to possess endotoxin or secrete
  exotoxins.
• Fully susceptible to lysis by serum and lysosomal
  enz.
• Extracellular dextran--adherence and propagation.
• FimA-- initial colonization of damaged heart
  tissue.
• Fibronectinadherence
• Lipoteichoic acid--adherence

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Clinical Manifestation Endocarditis
Bacteremia Meningitis pneumonia
Miscellanous Infection
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Endocarditis preantibiotic 75 of case of
infective endocarditis current 30-40 Cause
endocarditis S.mitis , S. sanguis , S.mutans ,
S. salivarius , S.gordonii , s .
Oralis -underlying valvular heart
disease -prosthetic valves
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Endocarditis
sign and symptoms. insidious onset
subacute but progressive course fever
constitutional symptoms fatigue, anorexia,weight
loss cardiac murmur splenomegaly
circulating immune complexes-Oslers node
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Endocarditis
Diagnosis viridans streptococci
bacteremia 96 of first blood culture 98 of
two blood culture Echocadiography identify
valvular dysfunction hemodynamic
complications myocardial abscesses findings
indicate for surgical intervention
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Endocarditis
Treatment -prolong penicillin therapy adequately
sterilized vegetations -gentamicin lead to more
rapid eradcation of the pathogen
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Bacteremia -2.6 positive blood culture -only
21 clinically significant. -Association Aggress
ive cytoreductive therapy, acute
leukemia allogeneic bone marrow transplantation
after high-dose cytosine arabinoside -Risk
factor profound neutropenia prophylactic
Bactrium or fluoroquinolone use antacid or H2
antagonists mucositis increase radiation to
oral cavity
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Bacteremia

• Sign and symptom
• -fever alone
• Organ dysfunction
• Fulminant shock syndrome
• hypotension
• rash
• palmar desquamation
• ARDS

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Bacteremia
Treatment -B-lactam aminoglycoside -prevent
streptococcal bacteremias is controversial. -ampic
illin prophylactic failed in bone marrow
transplant
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• Meningitis
• -S.salivarius most common.
• -S.mitis and S.sanguis
• Source endogenous flora
• Neonatal meningitis-perinatallry from mother
• Review of viridans streptococcal meningitis(55
  case)
• 31 ear,nose, throat
• 13 endocarditis
• 8 head trauma or neurosurgery
• 35 illidentifield

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Meningitis
Predisposing factors -gastrointestinal
pathology -gastrointestinal manipulation -trauma -
ganglionic thermocoagulation -severe
immunocompromise after CMT -after lumbar puncture
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Meningitis
Sign and symptoms -all ages , neonates. -typical
of acute pyogenic meningitis -meningeal
irritation -Neurologic deficits -seizures -altered
sensorium
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Meningitis
Diagnosis -CSF parameters prot. and WBC
counts abnormal glucose normal positive Gram
stain CSF culture Differentiation from S.
pneumoniae Review CSF culture --hemolytic
streptococci 43 pts. 19 --clinically
relevant. Dx.--clinical setting CSF laboratory
parameters. Contaminants than pathogen
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Meningitis
Treatment -penicillin G 24 Mu / day ( MIC 0.1
ug/ml ) (antibiotic of choice) -antibiotic
resistant viridans streptococci (MIC gt 4 ug/ml
) vancomycin plus 3nd generation cephalosporin
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Pneumonia -normal oral flora -if culture from
lower respiratory tract specimens, trantracheal
aspiration , protected bronchial
brush aspiration pneumonia syndrome -Predispo
sing host factors older ( 49-80 yr.) multiple
underlying conditions alcoholism lung
carcinoma DM
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Pneumonia
-Prognosis primary viridans streptococcal
pneumonia good -treatment penicillin G
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Miscellaneous infection localized purulent
collections asso. S.milleri group pericarditis
peritonitis acute bacterial sialadenitis orof
acial odontoenic infection endophthalmitis upp
er respiratory tract infection(otitis media ,
sinusitis)
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Therapy

• In the past
• -viridans group streptococci-susceptible to most
  antibiotic
• 1993-1994
• -44 susceptible to penicillin
• Resistance nosocomial blood-stream
• -immunocompromised pt.

• 98 nosocomial blood stream
• -61 susceptible penicillin
• - lt43 susceptible penicilin
• (neutropenic cancer pt.)

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Therapy
Resistance latter group. -antimicrobial
prophylaxis with cancer chemotherapy. Community
-remaining of susceptible to penicillin -1986-gt
review-gtendocarditis 2 of 31 viridans
streptococcal-gt penicillin resistant. penicillin
prophylaxis ?children with rheumatic fever î
number of penicillin resistant strains. -some
strains-gtexhibit a high level of resistance to
penicillin
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Therapy
-USA high-level penicillin resistance 5-13
non-B lactamaseproducing posses altered
penicillin binding proteins. -Species least
sensitive S.mitis S.sanguis
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• Tolerance
• Animal model of endocarditis
• tolerance stains -gt eradicated more slowly from
  
• vegetation than non tolerance strain
• -most -gt S. sanguis and S. gordonii
• -minority -gt S.mitis
• -No clinical significance -gt attached to
  tolerance
• -Relapse after 4 wks. course of high-dose
  parenteral
• penicillin -gt rare
• not been asso. with tolerance in the pathogen

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Therapy
Other B-lactum ATB . -In vitro ?????? ? ???
penicillin Community-acquired endocarditis Ceftr
iaxone inh. 100 of 20 endocarditis strain
at concentration 2.0 ug/ml or less - 80 (16
strain) susceptible to 0.25 ug/ml or
less Hospitalized or neutropenic cancer
pt. Ceftriaxone- less activity - 15-23
resistance - high level resistance to
penicillin (MIC gt 4 ug/ml)
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Aminoglycosides viridans streptococci are
resistant - synergistic bactericidal
activity (penicillinaminoglycosides) Streptom
ycin MIC 1000 ug/ml or greater In vitro -good
activity against viridans streptococci
chloramphenicol vancomycin fluoroguinolones
ofloxacin sparfloxacin levofloxacin
neutropenic cancer pt. prophylaxis
quinolone High level resistance
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-Variable activity -25-50 reported
resistant Tetracycline Clindamycin Erythromycin
-most-strains of viridans streptococci are
resistant Trimethoprim-sulfamethoxazole
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Nutritionally variant of viridans streptococi
(NVS) (Abiotrophia) -described 1961
fastidious gram-positive bacteria -grow
as satellite colonies around other bacteria -o
riginally -endocarditis -otitis media -Mutant
subspecies of S. mitis (S.mitior) -Evidence for
similarity between NVS and S.mitis
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DNA-DNA hybridization studies ????? -NVS -gt
streptococcus ??? taxonomically unrelated
viridans group ???? ? -name-gt S.adjacens and S.
defectivus -?????????????????? ???? 2 ??????
relate ??? streptococcus ??????? ? ??? -1995 -gt
new genus -gt Abiotrophia -gtA.adjacens ,
A.defectiva resistant to optochin susceptible
to vancomycin -Colonies -non hemolysis -or
-hemolysis -Normal flora -upper
respiratory -urogenital -gastrointestinal
tract
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Historically -NVS ??????? case culture negative
endocarditis -endocarditis caused by NVS greater
morbidity and motality gt other
streptococci -Comparison -49 NVS
endocarditis -130 other oral species
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-?????????????? NVS ??? viridans streptococc
Therapy In vitro Penicillin NVS less
susceptible to penicillin (MIC 0.2-2.0
ug/ml) Aminoglycosides-NVS variable in activity
against (MIC 0.5-32 ug/ml)
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Therapy -synergy ??????? penicillin or
vancomycin ??? aminoglycoside????? -penicillin
low dose gentamicin superior penicillin low
dose streptomycin NVS -gt susceptible vancomycin
erythromycin clindamycin rifampinvancomyci
n chloramphenicol NVS-gt variable cephalosporin
tetracycline
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-NVS in other disease is unknow (grow poorly on
solid media) -NVS ??? reported ?? pancreatic
abscess otitis media conjuctivitis infectiou
s crystalline keratopathy cirrhosis postpartum
and postabortal sepsis
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ß-hemolytic streptococci (group C and G)
Microbiology -Group C streptococci -common
pathogens in domestic animal, bird,
rabbit -bacitracin resistance -four species
Streptococcus dysgalactiae uncommon in
human mastitis in cows and suppurative
polyarthritis in lambs not streptolysin O or S
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Microbiology
Streptococcus equisimilis most common cause
infection in humans produces streptokinase and
streptolysin O but not streptolysin S throat
, nose , genital tract, umbilicus domestic
animal Streptococcus zooepidermicus infection
in domestic animal human infection-gttraced to
animal source not streptolysin O or S
,streptokinase Streptococcus equi pathogen of
young horses not streptolysin O or S ,
streptokinase
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Microbiology
-Group G streptococci B-hemolytic
streptococcal produce streptolysin similar to
streptolysin O by group A B-hemolytic
streptococci
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Epidemiology
Group C streptococci -normal human flora
nasopharynx skin genital
tract umbilical in newborns
puerperal vaginal -colonized in many
animal -Infection in humans traced to animal
sources -underlying condition
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Review 31 case group C streptococal
infection -26 cardiopulmonary disease -20
DM -20 chronic dermatologic condition -19
immunosupression -13 alcohol abuse -10 renal
or hepatic failure -6 injection drug use
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Review 88 case -group C streptococcal
bacteremia -73 underlying --20 cardiovascular
dis. --20 malignancy -24 exposure to
amimal
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Epidemiology
Group G streptococci -colonized nasopharynx
- skin - genital tract -
intestinal -Group G streptococal infection -65
underlying malignancy
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Review 57 case group G streptococcal
infection -21 underlying malignancy -21
alcohol use -14 DM
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Clinical Manifestations -suppurative infection
of various organ -endogenous organism residing
on skin or mucous membranes neonate ,
elderly alcoholism injection drug
abuse DM immunosuppressive therapy with
corticosteroid or cytotoxic drugs underlying
malignancy severe resembling groups A and B
ß-hemolytic streptococci -exogenous animal
sources
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Pharyngitis
Sign and symptoms -group C streptococci
pharyngitis similar group A ß-hemolytic
streptococci -fever -mild to moderate sore
throat -pharyngeal exudate -cervical
adenopathy -severe pharyngitis followed by
bacteremia , metastatic infection
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Pharyngitis
-group G streptococci asymptomatic pharyngeal
carriage -mild upper respiratory tract
infection -exudative pharyngitis with
fever -lymphadenopathy
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Complications of pharyngitis -Poststreptococcal
glomerulonephritis asso. Group C -acquired by
unpasteurized milk from cattle with
mastitis -S.zooepidemicus -No ASO antibody
titer response -pathogenesis is unclear
- Group G streptococcal pharyngitis asso. with
sterile reactive arthritis
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Skin and soft tissue infection -cellulitis ,
wound infection , pyoderma , erysipelas impetigo
, cutaneous ulcers. -Group C cellulitis after
vein harvest for coronary Artery bypass
grafts -Group G streptococcal bacteremia -skin
and soft Tissue infection ( underlying
malignancy)
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Arthritis -Group C streptococcal arthritis
-gtjoints with preexisting rheumatologic
abnormalities , polyarthritis -Group G
streptococcal -gt prosthetic joints.
Osteomyelitis -Group G -gt underlying
condition (malignancy , alcoholic cirrhosis ,
osteoarthritis , internal fixation for fracture ,
prosthesis )
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Respiratory tract infection
-Group C - uncommon cause of pneumonia -
preceded by viral URI -Group G - rare
-underlying malignancy
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Endocarditis
-Groups C and G streptococci is uncommon -Group
C streptococcal endocarditis subacutely major
emboli to CNS , eye , limb , lung poorly
response to single B-lactam favor use
bactericidal combination (penicillin plus
gentamicin) -Group G streptococcal
endocarditis older pt. with multiple underlying
disorders affect to both native and prosthetic
valves left sided more common abrupt onset
with rapid valve destructon and perivalvular
infection B-lactam plus aminoglycoside at least
28 days.
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Meningitis -Groups C and G streptococcal
meningitis asso. with infective
endocarditis. -occur in healthy patients
equine zoonosis - ingestion of unpasterized goat
s milk -Group C streptococci - CSF in a
preterm infant-gt mother received intrapartum
antimicrobial therapy for chorioamnionitis.
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Puerperal infection -Groups C and G streptococci
asso. epidemic and nonepidemic puerperal sepsis
and endometritis
Neonatal Sepsis -Group G streptococci neonatal
sepsis premature low birth weight
infants premature rupture membranes onset
within the first week of life asso.-high
incidence of maternal obstetric complication
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Miscellaneous infection -Group C
streptococcal -pericarditis -pyomiositis in
AIDS -Henoch schonlein purpura -brain abscess ,
subdural empyema -epiglottis -infected
arteriovenous fistular -peritonitis in dialysis
pt. -Group G streptococcal -spinal epidural
abscess -brain abscess in HIV -panophthalmitis
-toxic shock like syndrome asso. both groups
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Therapy
Group C streptococcai -drug of choice -gt
penicillin G -Good activity-gt cefazolin ,
vancomycin , cefotaxime -variable -gt
tetracycline -resistant -gt erythromycin -synergy
-gt penicillin plus gentamicin (recommend for
pt. with severe infection)
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Group G streptococci -Good activity-gt penicillin
, ampicillin , cefotaxime vancomycin
,cephalosporins -Relatively poor activity -gt
clindamycim , chloramphenicol
erythromycin -synergy -gt gentamicin with either
penicillin cefotaxime
vancomycin against 80-90
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