Streptococcal Infection

Streptococcus pyogenes (strep A) causes multiple important infections:

1. Pharyngitis: look for sore throat with fever, tonsillar exudate, enlarged tender cervical nodes, and leukocytosis. Streptococcal throat culture confirms the diagnosis. Elevated an tistreptolysin O (ASO) and anti-DNase titers also are used retrospectively when needed (rheumatic fever, post-streptococcal glomerulonephritis).Treat with penicillin to avoid rheumatic fever and scarlet fever.

»Rheumatic fever: diagnosis is made by history of streptococcal pharyngitis and Jones criteria, major (migratory polyarthritis, carditis, chorea, erythema marginatum, subcutaneous nodules) and minor (elevated erythrocyte sedimentation rate, Greactive pro tein, white blood cell count, and ASO titer; prolonged PR interval; arthralgia). Treat with aspirin; steroids are used for severe carditis (e.g., congestive heart failure). After rheumatic fever, patients need continuous prophylaxis against streptococci (benzathine penicillin intramuscularly every month or orally for compliant patients; erythromycin for penicillin-allergic patient) until age 18 (or longer) plus endocarditis prophylaxis before surgical procedures. Treatment of streptococcal pharyngi tis reduces the incidence of rheumatic fever.

a Scarlet fever: some untreated cases progress to scarlet fever if the streptococcal species produces erythrogenic toxin. Symptoms include red flush in skin (which blanches with pressure, classically with eireumoral pallor), truncal rash, strawberry tongue, and late skin desquamation. Kawasaki's syndrome is another cause of this set of symptoms.

« Post-streptococcal glomerulonephritis: occurs most commonly after a skin infection but may occur after pharyngitis. The patient presents with history of streptococcal infection (by a nephritogenic strain) T -3 weeks earlier and abrupt onset of hematuria, proteinuria (mild, not in nephrotic range), red blood cell casts, hypertension, edema (especially periorbital), and elevated BUN/creatinine. Treat support) vely: control blood pressure, and use diuretics for severe edema. Treating streptococcal infections does not reduce the incidence.

2. Skin infections: often occur after a break in the skin due to trauma, scabies, or insect bite.

Watch for development of post-streptococcal glomerulonephritis:

sImpetigo: maculopapules, vesicopustules/bullae, or honey-colored, crusted lesions. Staphylococci are a more frequent cattse than streptococci. .Definitely think of staphylococci. if a furuncle or carbuncle is present; think of streptococci i f glomerulonephri tis occurs. Infection is contagious; watch for sick contacts. Treat empirically with anti-staphylococcal penicillin (e.g., dicl oxacillin).

a Erysipelas: a superficial cellulitis that is red, shiny, swollen, and tender; may be associated with vesicles and bullae, fever, and lymphadenopathy.

»Cellulitis: involves subcutaneous tissues (deeper than erysipelas). Streptococci are the most common cause, but staphylococci also may be implicated. Treat empirically with ant ¡staphylococcal penicillin or vancomycin to cover both. If Pseudomonas sp. is suspected (diabetic foot ulcers, burns, severe trauma), treat with broad-spectrum penicillin plus an aminoglycoside. If Pas teure) ¡a multocida is suspected (after dog or cat bites), treat with IV ampiciliin. If Vibrio vulnificus is suspected (fishermen or other salt -water exposure), treat with tetracycline.

® Necrotizing fascii tis: progression of cellulitis t;o necrosis and gangrene, crepitus, and systemic toxicity (tachycardia, fever, hypotension). Often multiple organisms (aerobes and anaerobes) are involved.Treat with IV fluids, incision and drainage or debridement, and broad-spectrum antibiotics (broad-spectrum penicillin or cephalosporin plus an aminoglycoside).

3. Endometritis/puerperal fever: postdelivery fever and uterine tenderness. Treat with amoxicillin/ampiciliin.

Streptococcus rigalactiac (strep B): famous as the most common cause of neonatal meningitis and sepsis; acquired from maternal birth canal, in which it is part of the normal flora. Penicillin-sensitive.

Streptococcus viridans: causes subacute endocarditis and dental caries (Streptococcus mutans).

Enterococcus faeculis: normal bowel flora; causes endocarditis, urinary tract infection, and sepsis.

Streptococcus pneumoniae: common cause of pneumonia, otitis media, meningitis, sinusitis, and sepsis.

Staphylococcus aureus: common cause of various infections:

w Abscess (especially in the breast after breast -feeding or in the skin after a furuncle) «Endocarditis (especially in drug users)

w Osteomyelitis (most common cause except in patients with sickle cell disease) « Septic arthritis

¡»Food poisoning (preformed toxin)

■ Toxic shock syndrome (preformed toxin, classically in a woman who leaves tampon in place too long and develops hypotension, fever, and a rash that desquamates)

a Scalded, skin syndrome (preformed toxin that affects younger children, who often start with impetigo, then desquamate)

«Impetigo a Cellulitis s Wound infections

■ Pneumonia (often forms lung abscess or empyema) b Furuncle or carbuncle

Note: Health care workers who are chronic nasal carriers may cause nosocomial infections. Treat carrier with antibiotics. Treat abscesses with incision and drainage, other infections with antistaphylococcal penicillin (e.g., methicillin, dicloxacillin) or vancomycin.

Staphylococcus epidermidis: causes IV catheter infections, infections of prosthetic implants (heart valves, vascular grafts), and sepsis. Treat empirically with antistaphylococcal penicillin or vancomycin.

Staphylococcus saprophyticus: common cause of urinary tract infection. Treat empirically with, standard urinary tract infection antibiotics.

Polymyalgia Polymyositis

Common terms to describe skin finding

PRIMARY UîSlON

Macule msiNiriow

Flat, cimmisuibed skin-discoloration that lacks ■ surface elevation or depression

MORPBOOH/V'

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