Advertisement Upgrade to remove ads

Chapter 18

Furuncle

Boil; results when an inflammation of hair follicle or sebaceous gland progresses into a pustule (S.aureus)

Folliculitis

Most common; mild; superficial inflammation of hair follicles (S.aureus)

Carbuncle

Deeper lesion created by aggregation of a cluster of furuncles into one large mass; extremely painful (S.aureus)

Erysipelas

Slightly more invasive form; edema and redness of the skin near the portal of entry, fever, chills; cutaneous lesions can
remain superficial or cause long term systemic complications
-S.pyogenes

Pyoderma (Streptococcal impetigo)

Burning, itching papules that break and form highly contagious crust
-S.pyogenes

GPC

Strep, staph, enterococcus

GNC

Neisseria

Staphylococcus

-Inhabitants of skin and mucous membranes
-Irregular clusters, short chains and pairs

S. aureus

-Among most resistant (high salts, temps, extreme pHs)
-Viable after months of air drying, resists many antibiotics and disinfectants

Coagulase

Coagulates plasma and blood; diagnostic (S.aureus)

Hyaluronidase

Digests the hyaluronic acid that binds connective tissue (S.aureus)
-extracellular in S.pyogenes

Staphylokinase

Digests blood clots (S.aureus)

Nuclease

Digests DNA (S.aureus)

Penicillinase

Inactivates penicillin (S.aureus)

Hemolysin

Lyse red blood cells (S.aureus)

Leukocidin

Lysis of neutrophils and macrophage (S.aureus)

Enterotoxin

Act upon gastrointestinal tract (S.aureus)

Exfoliative toxin

Causes skin to peel away; responsible for staphylococcal scalded skin syndrome (S.aureus)

Toxic Shock Syndrome Toxin (TSST)

Probable role in development of toxic shock syndrome (S.aureus)

Bullous Impetigo

Bubble-like epidermal swellings that can break and peel away; most common in newborn (S.aureus)

Osteomyelitis

Pathogen is established in the highly vascular metaphyses of a variety of bones; abscess form (S.aureus)

Bacteremia

Primary origin is bacteria from another infected site or from colonized medical devices; endocarditis possible (S.aureus)

Pneumonia

As nasopharynx is one of the colonization site, pathogens can be aspirated into lungs and cause pneumonia involving multiple lung abscesses (S.aureus)

Food Intoxication

Ingestion of heat stable enterotoxins; food poisoning; cramping, nausea, vomiting, diarrhea

Staph Scalded Skin Syndrome

Toxemia; upon reaching the skin the toxin induces bright red flush; blisters, then desquamation of the epidermis

Toxic Shock Syndrome

Fever, vomiting, rash, potentially fatal complications involving liver, kidney etc.

S. epidermidis

Infections usually occur after surgical procedures such as insertion of catheters; biofilm formation along with other CNS
species
-endocarditis, UTI, coagulase negative

S. saprophyticus

Infrequent resident of the skin, lower intestinal tract & vagina; UTI

MRSA

methicillin-resistant S.aureus

Group A

S. pyogenes

C Carbohydrates

Protect against lysozyme
-surface antigen S. pyogenes

Lipoteichoic acid

-Contributes to adherence
-Bound to fimbriae
-surface antigen S. pyogenes

M-Protein

Resists to phagocytosis, improves adherence
-surface antigen S. pyogenes

Hyaluronic Acid Capsule

Provokes no immune response, antiphagocytic
-surface antigen S. pyogenes

Streptolysin

Hemolysin; injure many cells and tissue
-extracellular toxin, S.pyogenes

Erythrogenic (pyrogenic) Toxin

Induces fever and responsible for typical red rash; key toxin in scarlet fever
-extracellular toxin, S.pyogenes

Streptokinase

Involved in digestion of fibrin clot
-extracellular, S.pyogenes

Streptococcal Pharyngitis

Strep throat
-S.pyogenes

Scarlet Fever

-Strep throat infection involving S.pyogenes carrying a prophage that codes for erythrogenic toxin
- high fever, diffuse rash
-Systemic infection

Streptococcal Toxic Shock Syndrome

Result of a profound bacteremia and deep tissue infection and rapidly progresses to multiple organ failure
-Systemic infection (S.pyogenes)

Rheumatic Fever

Usually follows an overt or subclinical streptococcal pharyngitis in children; carditis, arthritis, fever, usually without lasting damage; in case of severe carditis, extensive valve and muscle damage possible
-sequelae Group A

Acute Glomerulonephritis

Damaged kidney cells can not adequately filter blood- nephritis, increased blood pressure; occasionally heart failure; may clear or become chronic leading to kidney failure
-sequelae Group A

Group B

Streptococcus agalactiae

Streptococcus agalactiae

Residents of human vagina, pharynx and large intestine
• Because of its location in vagina can be transferred to infant during delivery and can cause severe infection
- most prevalent cause of neonatal pneumonia, sepsis and meningitis
- Pregnant women should be screened for colonization and treated.

Enterococcus faecalis

- normal colonists of human large intestine
- Infections arise most often in elderly patients undergoing surgery and affect the urinary tract, wounds etc
- Group D

Group C and G

Common flora of domestic animals; frequently isolated from human upper respiratory tract; occasionally imitate group A streptococci in causing pharyngitis, glomerulonephritis;
bacteremia in severely compromised patients

Subacute Endocarditis

Blood-borne bacteria settle on heart lining or valves that have been previously damaged by rheumatic fever, valve surgery etc; biofilm formation called vegetation; vegetations release masses of bacteria into circulation
-complication of viridans infections

S.pneumoniae

Involved in 60-70% of bacterial pneumoniawhich primarily affect immunocompromise

Otitis Media

Gains access to the chamber of middle ear by way of eustachian tube and cause a middle year infection called otitis media; occurs readily in children under 2 years
-S.pneumoniae

Meningitis

Young children upper respiratory tract infection
-S.pneumoniae

Pneumococcal Treatment

• Traditionally treated with penicillin G or V
• Increased drug resistance
• Two vaccines available

Primary Neisseriaceae Pathogens

gonorrhea, mengintidis

Males (gonorrhea)

Infection of urethra causes urethritis with yellowish discharge; can cause infertility (10 percent asymptomatic)

Females (gonorrhea)

Bloody vaginal discharge, painful urination if urethra is infected; in case of ascending infection -PID (pelvic inflammatory disease) possible; can cause sterility (50 percent asymptomatic)

Opthalmia Neonatorum

Gonococcal eye infections in babies during pregnancy
-prevented by prophylaxis immediately after birth

Gonococcal Diagnosis

Gram stain - presence of Gram-negative diplococci

PPNG

Penicillinase producing N. gonorrhoeae

TRNG

Tetracycline resistant N. Gonorrhoeae

Meningitis Treatment

Treated with intravenous penicillin G, cephalosprin
• Prophylactic treatment of family members, medical personnel, or children in day care who have come in close contact with infected people
• Vaccines available

Branhamella

Found in nasopharynx; significant opportunist in hosts with disturbed immune functions

Moraxella

Short, plump rods as well as cocci; widely distributed on mucous membranes, weakly pathogenic or non pathogenic

Please allow access to your computer’s microphone to use Voice Recording.

Having trouble? Click here for help.

We can’t access your microphone!

Click the icon above to update your browser permissions above and try again

Example:

Reload the page to try again!

Reload

Press Cmd-0 to reset your zoom

Press Ctrl-0 to reset your zoom

It looks like your browser might be zoomed in or out. Your browser needs to be zoomed to a normal size to record audio.

Please upgrade Flash or install Chrome
to use Voice Recording.

For more help, see our troubleshooting page.

Your microphone is muted

For help fixing this issue, see this FAQ.

Star this term

You can study starred terms together

NEW! Voice Recording

Create Set