2025 – PAGE 300 – INFECTIOUS DISEASES

ALPHA HEMOLYTIC STREPTOCOCCUS (VIRIDANS AND PNEUMONIAE)

Streptococcus viridans and Streptococcus pneumoniae (AKA STREP PNEUMONIAE or PNEUMOCOCCUS) are alpha hemolytic strep species

• MNEMONIC: Imagine a GREEN ALF doing a “STREP” tease dance and showing you his NEW MOVE TODAY (or NEW MOON TODAY = pneu-moon).
  • KEY: Green = Verde = Viridans. ALF = Alien Life Form = Alpha. New Move Today (or New Moon Today) = Pneumonia
• MNEMONIC: (VIDEO – watch the dance!) – www.pbrlinks.com/ALPHAHEMOLYTIC1
• MNEMONIC: (Image – Green ALF) www.pbrlinks.com/ALPHAHEMOLYTIC2

BETA HEMOLYTIC STREPTOCOCCUS (AGALACTIAE AND PYOGENES)

Streptococcus agalactiae (a Group B Strep, AKA the GBS you need to know!) and Streptococcus pyogenes (a Group A Strep) are beta hemolytic strep species.

• MNEMONIC: The names and groups are confusing, so go over this again and again until you get it. Or create your own mnemonics.
  • aBpA!: If you can remember that acronym, you’re set! If you have trouble remembering the order of the letters, maybe you’ve heard of Acute BronchoPulmonary Aspergillosis? For aBpA, the lower case letter represent the correct nomenclature of agalactiae and pyogenes! The upper case letters are always upper case when written—group A and group B! Write aBpA and circle the two groups of letters when you get confused. It helps!aB = agalactiae of group B strep = GBS = gBs = Baby!
    pA = pyogenes of group A = “GAS” = gaS = Skin!

• MNEMONIC: Inhaling GAS makes my THROAT HURT! This may help you remember that group A strep (pyogenes) is the one that causes pHARYNGITIS and oral abscesses! pYOGENes is pYOGENic in the skin and in the oral cavity!

STREPTOCOCCAL PHARYNGITIS (AKA STREP PHARYNGITIS or STREP THROAT)

To identify Streptococcal pharyngitis, look for fever, lymphadenopathy, sore throat, erythematous, or exudative tonsils and the ABSENCE of coughing, sneezing, and rhinorrhea (those are viral symptoms). The pharyngitis is due to Group A Streptococcus and usually resolves in 2–5 days. Diagnose by CULTURE. If a rapid Strep is positive, TREAT. If negative, send for a CULTURE. The only reason Strep throat is such a big deal is because it can lead to RHEUMATIC FEVER, which is PREVENTABLE! Treat with PENICILLIN or AMOXICILLIN. If allergic, use erythromycin or clindamycin.

PEARLS: Antibiotics are NOT given to shorten the course of the illness. They are given to prevent RHEUMATIC FEVER! Even given 9 days after the onset of symptoms, RHEUMATIC FEVER can be prevented! ALWAYS get a culture. Consider treating if you have a strong clinical case or suspect poor clinical follow up. Rheumatic fever is NOT due to GAS skin infections!

(DOUBLE TAKE) POSTSTREPTOCOCCAL GLOMERULONEPHRITIS (PSGN, AKA POST INFECTIOUS GLOMERULONEPHRITIS)

Poststreptococcal glomerulonephritis (PSGN, AKA post infectious glomerulonephritis) is a Group A Streptococcus (GAS) syndrome. Look for HEMATURIA + PROTEINURIA ± swelling ± HTN. There may be a history of a skin infection one month before, or a throat infection 1–2 weeks earlier. Labs will show a low C3 and NORMAL C4 ± renal impairment. Biopsy will show LUMPY BUMPY IgG deposits (biopsy is not required to make the diagnosis). Treat with IVF and a loop diuretic if there’s HTN. This generally has a GOOD prognosis, but you may consider steroids or cyclophosphamide for cases that are not improving. C3 should be followed until it’s back up to normal.

PEARL: Antibiotics given for a Group A Strep infection can prevent rheumatic fever, but they CANNOT prevent PSGN. Also, PSGN can occur from pharyngitis OR skin infections, but rheumatic fever only occurs after PHARYNGITIS.

PEARL: If the C3 level does not come back up to normal after 6 weeks, consider a different diagnosis, such as membranoproliferative glomerulonephritis  (low C3 and normal C4) or lupus nephritis (+ANA, low C3 and C4). If the renal impairment is severe, obtain a biopsy to look for rapidly progressive glomerulonephritis (RPGN).