Micro Exam 2: Streptococcus and Enterococcus

Bacteremia

25-30% of patients with pneumonia develop this; more common in patients with meningitis than with pneumonia, otitis, media, or sinusitis; overwhelming sepsis in asplenic patients

Streptolysin O

A Group A S. Pyogenes oxygen labile hemolysin capable of lysing erythrocytes, leukocytes, and platelets

13- and 23- valent (Prevnar 13)

A ______________________ pneumococcal polysaccharide vaccine is recommended for children older than 2 years and adults over 60 years. Boosters may be needed because polysaccharides are T-independent antigens stimulating only mature B lymphocytes (not as powerful)

Amidase

A bacterial enzyme of S. Pneumoniae that enhances release of the cell wall components, producing more inflammation (teichoic acid and peptidoglycan fragments tend to activate complement pathways, producing pro inflammatory C5a). Peroxide of the bacteria causes tissue damage.

Rheumatic fever

A nonsuppurative complication of S. Pyogenes pharyngitis; characterized by inflammatory changes of the heart (pancarditis), joints (arthralgias to arthritis), blood vessels, and subcutaneous tissues; specific class I M proteins (1,3,5,6 and 18); most common in young school age children; vigorous antibody response but can recur with a different streptococcal infection - antibiotic prophylaxis necessary (I.e. before dental procedures) -> recurrence decreases with time

G.V. Black (1883)

A self taught dentist who hypothesized that microorganisms produce toxic substances that cause caries

W.D. Miller (1881)

A student of Koch who discovered that bacteria are the cause of dental caries

Erysipelas

A suppurative infection of S. Pyogenes; Localized acute skin infection with pain, inflammation, lymph node enlargement, and systemic symptoms (chills, fever, leukocytosis); occurs more commonly in young children or older adults, historically on the face but now more commonly on the legs

Necrotizing fasciitis

A suppurative infection of S. Pyogenes; deep infection of the skin that involves destruction of muscle and fat layers "flesh -eating bacteria", spreads along fascial planes - toxicity, multiorgan failure and death can occur; antibiotic therapy plus aggressive surgical debridement of infected tissue

Scarlet fever

A suppurative infection of S. Pyogenes; diffuse erythematous rash beginning on the chest and spreading to the extremities; complication of streptococcal pharyngitis (bacteriophage produces a pyrogenic exotoxin), 1 to 2 days after pharyngitis, rash disappears in 5-7 days followed by desquamation of superficial skin layer

Cellulitis

A suppurative infection of S. Pyogenes; infection of the skin that involves the subcutaneous tissues; distinction between infected and non infected skin is not as clear; systemic signs observed; many other organisms can cause (including Staphylococcus)

Pyoderma (impetigo)

A suppurative infection of S. Pyogenes; localized skin infection with vesicles progressing to pustules; no evidence of systemic disease; primarily affects exposed areas (face, arms, legs) after direct contact with an infected person or fomites (contaminated objects)

Streptococcal toxic shock syndrome

A suppurative infection of S. Pyogenes; multiorgan systemic infection resembling staphylococcal toxic shock syndrome; however, most patients are bacteremic and with evidence of fasciitis; different strain than that causing pharyngitis - most M serotypes 1 or 3, many have mucopolysaccharide hyaluronic acid capsules (mucoid strains); also produce SpeA and SpeC

Pharyngitis

A suppurative infection of S. Pyogenes; reddened pharynx with exudates generally present; cervical lymphadenopathy can be prominent; develops 2-4 days after exposure, sore throat, fever, malaise, and headache; differentiated streptococcal from viral is difficult - antibody test required

Pleurisy

A symptom of S. Pneumoniae (along with fever of 39C-41C and severe shaking chills) is productive cough with blood tinged sputum , with chest pain - also called ___________.

ASO test

A test useful for documenting recent group A streptococcal infection; testing for antibodies readily formed against streptolysin O (antistreptolysin O) - ASO irreversibly inhibited by cholesterol in skin lipids, so patients with cutaneous infections do not develop ASO antibodies; useful for confirming rheumatic fever or acute glomerulonephritis

Streptococcus pneumoniae

A viridian streptococci that are diplococci, encapsulated (in virulent strains) gram positive; alpha hemolytic if incubated aerobically on blood agar; can ferment carbohydrates producing lactic acid byproduct but lacks catalase (limits growth); capsular polysaccharides (aka specific soluble substances- 94 serotypes)

Peritonitis

Abdominal swelling and tenderness after abdominal trauma or surgery; patients typically are acutely ill and febrile and have positive blood cultures; typically a polymicrobic infection (Enterococcus included)

Late-onset neonatal disease

Acquired from an exogenous source (mother, another infant); predominant manifestation is bacteremia with meningitis, neurologic complications are common in children with meningitis ( 25% to 50%) - (S. Agalactiae Group B infection)

Pneumolysin

An enzyme that degrades hemoglobin, producing a green product; creates the alpha hemolytic appearance on blood agar - acts by creating pores in cell membranes of host cells; activates classic complement pathway resulting in production of proinflammatory C3a and C5a, and suppresses oxidative burst of phagocytosis

Optochin (ethylhydrocupreine dihydrochloride)

An isolate is streaked onto a blood agar plate and a disk saturated with ____________ is placed in the middle of the inoculum. A zone of inhibited bacterial growth is send around the disk after overnight incubation (S. Pneumonia growth is inhibited, Enterococci are resistant)

Salivary pellicle

Antigen I/II (vaccine candidates) associated on the cell wall of S. Mutans, attach to this thin layer of proteins and glycoproteins at the tooth surface

Bacteremia

Associated with either a localized infection or endocarditis (Enterococcus infection)

Streptococcus mutans

Associated with enamel caries in children and young adults, root surface caries in elderly, and nursing (or bottle) caries in infants (a viridian - alpha hemolysis)

Sinusitis and Otitis media

Associated with paranasal and ear infections; a disease that could occur with S. Pneumoniae, especially in young children

Meningitis

Can follow bacteremia of S. Pneumoniae, with severe infection involving the meninges, with headache, fever, and sepsis; high mortality and severe neurologic deficits in survivors

Puerperal sepsis

Caused by S. Agalactiae, postpartum infections

Early-onset neonatal disease

Characterized by bactermia, pneumonia, or meningitis from S. Agalactiae (group B) infection; examination of CSF required for all infected children; 15-30% who survive meningitis have severe neurological sequelae, including blindness, deafness, and mental retardation

Streptococcus agalactiae (Group B)

Colonize the lower gastrointestinal tract, genitourinary tract, and transient vaginal carriage has been observed in pregnant women; the most common cause of bacterial septicemia pneumonia and meningitis in newborns (intrapartum antibotic prophylaxis utilized); screened for colonization at 35-37 weeks gestation

Viridans Streptococci

Colonize the oropharynx, heterogeneous collection of alpha hemolytic (green tint hemolysis) and non hemolytic streptococci; nutritionally fastidious requiring complex media supplemented with blood products

Endodontitis

Commonly detected in asymptomatic, persistent endodontic infections (Enterococcus faecalis)

beta hemolysis

Complete hemolysis; examples include Streptococcus pyogenes and Streptococcus agalactiae

F antigen

Covalently bound to plasma membrane lipids of S. Pneumoniae that cross react with Forsmann surface antigen on mammalian cells

Leukocytes

Diagnosing S. Pyogenes (Group A) via microscopy: gram positive-cocci in pairs or chains in association with _________________ is important

Urinary tract infection

Dysuria and pyruria, most commonly in hospitalized patients with an in dwelling urinary catheter and receiving broad sepctrum cephalosporin antibiotics that wipe our normal flora (a disease of Enterococcus)

Group D

Enterococci were previously classified as ___________ _____ streptococci because they contain the glycerol teichoic acid antigen along with other streptococci

Vancomycin

Enterococcus gallinarum and Enterococcus casseliflavus are common colonizers of the human intestinal tract and are important because these species are inherently __________________ resistant.

Inherently resistant

Enterococcus organisms are _____________ ____________ to many antibiotics (e.g. oxacillin, cephalosporins) or have acquired resistance (aminoglycosides, vancomycin); patients who are immunocomprised are particularly susceptible

Secretory IgA protease

Enzyme of S. Pneumoniae that inhibits IgA mucus entrapment in order to evade the immune response

Enterococcus

Gram positive cocci that can grow both aerobically and anerobically in a broad temperature range (10C to 45C) in a wide pH range (4.6 to 9.9), and in the presence of high concentrations of sodium chloride and bile salts; variation in degree of hemolysis

Streptokinase (A and B)

Group A S. Pyogenes enzyme that mediates the cleavage of plasminogen, releasing the protease plasmin that, in turn, cleaves fibrin and fibrinogen lysing blood clots and fibrin deposits to facilitate spread of infection; anti-streptokinase antibodies are a useful marker for infection

J.K. Clark (1924)

Identified the bacterial cause of caries as Streptococcus mutans

Anti-DNase B test

In addition to the ASO test, an ____________________ can be used for antibody detection to confirm an S. Pyogenes (Group A) infection

Strawberry tongue

In scarlet fever, a yellowish-white coating initially covers tongue and is later shed revealing a red, raw surface beneath

Circumoral pallor

In scarlet fever, the area around the mouth is generally spared of rash, as are the palms and soles

Pastia lines

In scarlet fever, the rash (which blanches when pressed) is seen on abdomen and in the skinfold, which are called ____________ __________.

Alpha hemolysis

Incomplete hemolysis; forms a greenish color at the colony site; example is Viridans Streptococci (S. Pneumoniae & S. Mutans)

Endocarditis

Infection of the heart endothelium or valves; associated with persistent bacteremia; can present acutely or chronically (enterococcus infection)

Nosocomial infection

Infections acquired in the hospital via urinary catheterization or instrumentation (cause of Enterococcus)

Nucleic acid based tests

Less sensitive than culture, but amplification assays to diagnose S. Pyogenes are the test of choice when available

F protein

Lipoteichoic acid and ____ ____________ in the cell wall of S. Pyogenes facilitate binding of host cells by complexing fibronectin, which is present on the host cell surface. Can also bind to epithelial cells.

Phosphorylcholine

Located in S. Pneumoniae cell wall and binds to receptors for platelet-activating factor at cells whereby the bacteria can enter the cells; when inside cells S. Pneumoniae is protected from opsonization and phagocytosis, spreading into blood and the central nervous system

C3b

M proteins on S. Pyogenes interfere with phagocytosis by blocking the binding of complement component ______, an important mediator of phagocytosis. May also be degraded by Factor H, which binds to the cell surface of the M protein.

M protein

Major type specific protein of Streptococcus pyogenes that extends from cytoplasmic membrane through peptidoglycan layer; two polypeptide chains complexed in an alpha helix (amino terminus that extends above the cell surface is responsible for the antigenic differences observed among unique serotypes)

Serotypes Ia and V

Most common in adult S. Agalactiae disease (Group B)

Gamma hemolysis

No hemolysis

Acute glomerulonephritis

Nonsuppurative infection of S. Pyogenes; acute inflammation of the renal glomeruli with edema, hypertension, hematuria, and proteinuria; M serotypes associated with disease, sequela of both pharyngeal and pyodermal streptococcal infections; young patients recover quickly, progressive irreversible loss observed in adults

C polysaccharide

One form of teichoic acid in Streptococcus pneumonia that is exposed at the cell surface, extending through the capsule; it is species specific and unrelated to Lancefield carbohydrate; precipitates serum C-reactive protein (CRP)

Streptococcal pyrogens exotoxins (Spe)

Originally called erythrogenic toxins, produced by lysogenic (organism infected by bacteriophage) strains of streptococci; similar to toxin produced in Corynebacterium diphtheria, believed to be responsible for many of the clinical manifestations of severe streptococcal disease (necrotizing fasciitis, toxic shock syndrome, and rash in scarlet fever)

Streptolysin S

Oxygen stable, nonimmunogenic group A S. Pyogenes toxin and acts as a hemolysin against erythrocytes, leukocytes, and platelets (responsible for the characteristic B-hemolysis seen on blood agar media); stimulates release of lysosomal contents after engulfment, with subsequent death of the phagocytic cell; produced in the presence of serum (serum stable)

Streptococcal pharyngitis

Penicillin, penicillin V, or amoxicillin are effective at treating ________________ ________________; for penicillin allergic patients use oral cephalosporin

Bile solubility test

Placing a drop of bile on an isolated colony; S. Pneumonia colonies are dissolved within a few minutes, other alpha hemolytic streptococci remained unchanged (Enterococci do not dissolve)

Quellung reaction

Polyvalent anticapsular antibody is mixed with suspected bacteria- microscopic refractiveness (swelling) is a positive reaction (used to diagnose S. Pneumoniae)

PYR (L-pyrrolidonyl arylamidase)

Produced in a 5 min spot test due to lysis when diagnosing Enterococcus

Paul Keys (1960)

Proved that caries was actually a transmissible disease

M-like proteins

Resemble M proteins in structure and are under the same regulatory control. Interfere with phagocytosis by binding the Fc fragments of antibodies (S. Pyogenes)

Serotype III

Responsible for most late-onset disease of S. Agalactiae (1 week to 3 months of life)

Pregnant women

S. Agalactiae (Group b) infections in ___________ __________ can cause postpartum endometritis, wound infection, and urinary tract infections during and immediately after pregnancy; secondary complications of bacteremia include endocarditis, meningitis, and osteomyelitis are rare

Narrow zone

S. Agalactiae are indistinguishable on gram stain from S. Pyogenes, large colonies with a ___________ ____________ of beta hemolysis

Cnm protein

S. Mutans can contribute to endocarditis following bacteremia after dental procedures by binding to _____________ on valve tissue

Acid tolerant

S. Mutans can tolerate a wide pH range and is therefore _______ __________.

Vancomycin

S. Pneumoniae has an increased resistance to penicillin so ______________ combined with ceftriaxone is used commonly for empirical treatment, followed by monotherapy with an effective cephalosporin or fluoroquinolone

Respiratory droplets

S. Pyogenes (group A) is spread through __________________ ______________ so crowding (such as in classrooms and day care facilities) can increase the opportunity for the organism to spread)

M and F proteins

S. Pyogenes can invade into epithelial cells via ____ ________ ____ ____________ due their ability to adhere and interact with host cell receptors.

Blood agar

S. Pyogenes growth is optimal on ___________ ________ media, and somewhat inhibited by glucose.

C5a peptidase

S. Pyogenes has a _____ ___________ on the surface to inactivate a particular chemoattractant of neutrophils and mononuclear phagocytes protecting the bacteria from early clearance from infected tissues.

Group A

S. Pyogenes is classified as ________ ____ Streptococcus in the Lancefield groupings (beta hemolysis); a dimer of N-acetylglucosamine and rhamnose (antigen used for rapid strep test)

Class II M Proteins

Serotype of S. Pyogenes NOT associated with rheumatic fever, but is associated with other diseases of strep; do not have exposed shared antigens

Class I M Proteins

Serotype of S. Pyogenes associated with rheumatic fever and other diseases of strep; exposed shared antigens

Hyaluronic acid capsule

Some strains of S. Pyogenes have an outer ____________ _________ ____________ that is antigenititcally indistinguishable from the hyaluronic acid in mammalian connective tissues; protects bacteria from phagocytic clearance; can become severe systemic infections

Superantigens

Spe acts as_________________.

E. Faecalis and E. Faecium

Strains of Enterococcus found in the large intestine in high concentrations and in the genitourinary tract

Negative

Streptococcus and Entercoccus are catalase __________________ gram positive cocci found growing in chains

Emm

The ________ gene superfamily (a complex of more than 20 genes) encode the M-like proteins, M proteins, and immunoglobulin-binding proteins for S. pyogenes

Lancefield groupings

The beta hemolytic streptococci are classified by _________________ _____________ (classification scheme based on polysaccharide on the surface; A to W)

SpeA, B, C, and F

The four immunologically distinct heat-labile streptococcal pyrogenic exotoxins

C antigen

The most common surface protein on S. Agalactiae is the ____ __________, which is used to determine if the mother is immune.

Ia, III, V

The serotypes most commonly associated with with early onset S. Agalactiae are _____, _____, and ______. (Less than 7 days old)

Capsular polysaccharides

There are nine type specific __________________ __________________ on S. Agalactiae (Ia, Ib, II to VIII); serotypes Ia, Ib, II, III, and V most commonly associated with colonization and disease; interfere with phagocytosis

Posterior oropharynx (tonsils)

To culture for S. Pyogenes, take from the _______________ _____________ purulent material and base of lesion and culture slow growth - takes 2-3 days

M protein

Untreated S. Pyogenes (group A) patients produce antibodies against ____ __________ that can result in long-lived immunity

Bronchopneumonia

When S. Pneumoniae infection is in generalized areas of lung

Lobar pneumonia

When S. Pneumoniae infection is localized to lower lobe of lung