streptococcal infections

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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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