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Qom University of Medical Sciences And Health ServicesMedical School
Supervisor: Dr. Javad Khodadadi
Provisioner: Mohammad Mahdi Shater
Streptococcal Infections
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Streptococcus
Streptos(like chain) + coccus(like Sphere)
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• Many varieties of them are normal flora• GAS , S.pyogenes: one of the most common bacterial infections of school-age children, post infectious syndromes of ARF and PSGN. • GBS, S. agalactiae: cause of bacterial sepsis and meningitis in newborns • Viridans streptococci: are the most common cause of bacterial endocarditis• Enterococci: E. faecalis, E. faecium
Streptococcus
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•Gram positive
•Most are facultative anaerobes, although some are strict anaerobes
•fastidious
Streptococcus
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Lancefield Classification•a serologic grouping based on the
reaction of specific antisera with bacterial cell-wall carbohydrate antigens
A,B,C,G/βD/γvariable/α
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A,B,C,G/β D/γvariable/α
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Group A Streptococci
• S.pyogenes
• 500,000 deaths per year
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Group A Streptococci
• Virulence factor:M-proteinHyaluronic acid capsule
Streptolysins S and Opyrogenic exotoxins(erythrogenic toxins)
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CLINICAL MANIFESTATIONS
Pharyngitis
Seen in patients of all agesRespiratory droplets are the usual mechanism
of spread, other routes, including food-borne outbreaks
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A culture positive case of streptococcal pharyngitis with typical tonsillar exudate in a 16 year old.
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Pharyngitis
The incubation period is 1–4 daysSymptoms include: sore throat fever and chills malaisesometimes abdominal complaints and
vomiting, particularly in childrenSymptoms are mild to severe
sore throat fever and chills
malaise, fever and chills abdominal complaints & vomiting
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the large tonsils with white exudate.
the petechiae, or small red spots, on the soft palate.
large tonsils in the back of the throat covered in white exudate.
Differential Diagnosis
• Viral infections is more probable if we see:• conjunctivitis• Coryza• Cough• hoarseness• discrete ulcerative lesions of the buccal or
pharyngeal mucosa
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Diagnose• The throat culture remains the diagnostic gold standard
• Vigorous rubbing of a sterile swab over both tonsillar pillars
• Rapid diagnostic kits generally are >95% specific• A negative result should be confirmed by throat culture
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Complications• uncommon with the widespread use of antibiotics • spread of infection from the pharyngeal mucosa to deeper
tissues by direct extension or by the hematogenous or lymphatic route
• Cervical lymphadenitis• Peritonsillar or retropharyngeal abscess, • Sinusitis• Otitis media• Meningitis • Bacteremia• Endocarditis• Pneumonia
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• ARF• PSGN
The Asymptomatic Carrier State
• No symptoms with positive culture
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Scarlet Fever
consists of streptococcal infection, usually pharyngitis, accompanied by rash
streptococcal pyrogenic exotoxins A, B, and C
Susceptibility to scarlet fever was correlated with results of the Dick test
scarlet fever rash may reflect a hypersensitivity reaction
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Scarlet FeverSymptoms of pharyngitisOn the first or second day of illness over the
upper trunk
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Scarlet FeverThen involve back and abdomen
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Scarlet Feverspreading to involve the extremities but sparing
the palms and soles
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Scarlet FeverThe rash is made up of minute papules(sandpaper)Finely punctate erythema has become confluent Circumoral pallor & strawberry tongue
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Scarlet FeverPastia’s line
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Scarlet FeverSubsidence of the rash in 6–9 days is followed after
several days by desquamation of the palms and soles
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Differential Diagnosis
• Other causes of fever and generalized rash:• Measles and other viral exanthems• Kawasaki disease• Toxic shock syndrome• Systemic allergic reactions (e.g., drug eruptions).
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Skin and Soft Tissue InfectionsImpetigo(Pyoderma)Cellulitis
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Impetigo(Pyoderma) a superficial infection of the skincaused by GAS and or Staphylococcus aureusmost often in young children (poor hygiene)Minor trauma, such as a scratch or an insect biteusual sites of involvement are the face (particularly
around the nose and mouth) and the legs
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Impetigo(Pyoderma)Begin as red papules, which evolve quickly into
vesicular and then pustular lesionsHoneycomb-like crustsGenerally not painful, and patients do not appear illFever is not a feature
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Differential Diagnosis
• Bullous impetigo due to S. aureus more extensive & paper-like crusts
• herpetic lesionsmore discrete, grouped vesicles positive Tzanck test
• culture In difficult cases
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Cellulitis Inoculation of organisms into the skin may lead to
cellulitisinfection involving the skin and subcutaneous
tissues may also be associated with lymphangitis One form of streptococcal cellulitis, erysipelas
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Erysipelas a bright red swollen appearance of the involved skinlesion is warm to the touch & may be tenderpeau d'orange texture(involvement of superficial lymphatics)superficial blebs(usually 2–3 days after onset)Fever and chillsMost occur on the malar area of the face
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Deep Soft-Tissue Infectionsstreptococcal myositisNecrotizing fasciitis (hemolytic streptococcal gangrene)
involves the superficial and/or deep fascia investing the muscles of an extremity or the trunk.
The source of the infection is the skin & bowel flora
Usually quite acuteSevere pain at the site of involvementMalaise, fever, chillsToxic appearancethe severity and extent of symptoms worsenskin appearance(erythema and edema)
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Pneumonia and EmpyemaGAS is an occasional cause of pneumoniaPleuritic chest painFever & chillsDyspneaCough is usually present Pleural effusion(≈ one-half of patients and always infected )Empyema fluid is usually visible by chest radiography
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Bacteremia, Puerperal SepsisBacteremia occurs rarely with otherwise
uncomplicated pharyngitis, occasionally with cellulitis or pneumonia, and relatively frequently with necrotizing fasciitis.
raises the possibility of endocarditis, an occult abscess, or osteomyelitis
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Streptococcal Toxic Shock SyndromeShock with multisystem organ failure
Prevention
• No vaccine against GAS is commercially available
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Streptococci of Groups C and G• occasionally cause human infections similar to those
caused by GAS• S. dysgalactiae
• Pharyngitis• Pneumonia• Bacteremia• Endocarditis • Septic arthritis• Puerperal sepsis• Cellulitis and soft-tissue infections• Some of species of group C Lancefield are zoonotic and
acquired from contact with animals or unpasteurized milk
• Meningitis• Epidural abscess• Intraabdominal abscess• Urinary tract infection• Aneonatal sepsis
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Group B Streptococci• GBS major cause of sepsis and meningitis in human
neonates• frequent cause of peripartum fever in women and an
occasional cause of serious infection in nonpregnant adults
• S. agalactiae
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Infection in Neonates
Early-onset infections Late-onset infections
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Occur within the first week of life
Acquired from the colonized maternal genital tract
Prematurity and maternal risk factors (prolonged labor, obstetric complications, and maternal fever)
Presentation of neonatal sepsis Pneumonia respiratory distress Lethargy Hypotension Bacteremic Meningitis
Early-onset infections
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occur in infants 1 week to 3 months old
acquired during delivery or during later contact with a colonized mother, nursery personnel, or another source
Meningitis is the most common manifestation
fever, lethargy or irritability, poor feeding, and seizures
Bacteremia, osteomyelitis, septic arthritis, and facial cellulitis, submandibular or preauricular adenitis
Late-onset infections
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Identification of high-risk carrier mothers and treatment with antibiotic or immunoprophylaxis
Screening for anogenital colonization at 35–37 weeks of pregnancy by a swab culture of the lower vagina and anorectum
Risk factors: preterm delivery, early rupture of membranes (>24 h before delivery), prolonged labor, fever, or chorioamnionitis
Vaccine may be for future
Prevention
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Peripartum fever, the most common manifestation
Related to symptoms of endometritis or chorioamnionitis
transitory bacteremia, meningitis or endocarditis
In old or chronic illness(diabetes mellitus or a malignancy):
Cellulitis and soft tissue infection , UTI, pneumonia, endocarditis, and septic arthritis meningitis, osteomyelitis, and intraabdominal or pelvic abscesses
Infection in Adults
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Nonenterococcal Group D Streptococci
• S.bovis (S.gallolyticus, S.infantarius, S.pasteurianus, S.letetiensis)
• S. bovis endocarditis is often associated with neoplasms of the GIT-most frequently, a colon carcinoma or polyp-but is also reported in association with other bowel lesions.
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Viridans Streptococci• S. salivarius, S. mitis, S. sanguis, and S. mutansNormal flora of the mouthEndocarditisfrequently in neutropenic patients, particularly after bone
marrow transplantation or high-dose chemotherapy for cancer
sepsis syndrome with high fever and shock
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Viridans Streptococci• S. intermedius, S. anginosus, and S. constellatus abscesses of brain and abdominal viscera infections of oral cavity or respiratory tract
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Other StreptococciAbiotrophia & Granulicatella Species (Nutritionally
Variant Streptococci)They cause infections like viridans Streptococci
S.suis cause meningitis in humans people that exposure to pigs
S.iniae infected humans who have handled live or freshly killed fish(Cellulitis, bacteremia, endocarditis)
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