Purpura fulminans is a feature of
Ans. c (Acute Meningococcemia) (Ref. Harrison 18th/ p 114)ACUTE MENINGOCOCCEMIA# Neisseria meningitidis# Petechiae rapidly becoming numerous, sometimes enlarging and becoming vesicular;# Trunk, extremities most commonly involved;# May appear on face, hands, feet;# May include Purpura fulminans reflecting disseminated intravascular coagulation;# Most common in children, individuals with asplenia or terminal complement component deficiency (C5-C8);# Hypotension, meningitis (sometimes preceded by upper respiratory infection) may occur.PURPURA FULMINANS# Feature of severe disseminated intravascular coagulation# Characterized by Large ecchymoses with sharply irregular shapes evolving into hemorrhagic bullae and then into black necrotic lesions# Individuals with sepsis (e.g., involving N. meningitidis), malignancy, or massive trauma; asplenic patients at high risk for sepsis are predisposed.Educational points: Organism (Gram)ToxinMode of actionRole in diseaseProtein synthesis inhibitorsCorynebacterium diphtheria (Th)Diphtheria toxin# ADP ribosyl transferase inactivates EF-2# Targets: heart, nerves, epitheliumInhibits eukaryotic cell protein synthesis Pseudomonas aeruginosa (- )Exotoxin A# ADP ribosyl transferase inactivates EF-2# Target: liverInhibits eukaryotic cell protein synthesis Shigella dysenteriae (-)Shiga toxinInterferes with 60S ribosomal subunit# Inhibits protein synthesis in eukaryotic cells# Enterotoxic, cytotoxic, and neurotoxic Enterohemorrhagic E coli (EHEC) (-)Verotoxin(Shiga-like)Interferes with 60S ribosomal sunbmitInhibits protein synthesis in eurokaryotic cellsNeurotoxinsClostridium tetani (Th)Tetanus toxinBlocks release of glycine and GABAInhibits neurotransmission in inhibitor synapses Clostridium botulinum (Th)Botulinum toxinBlocks release of acetylcholineInhibits cholinergic synapsesEndotoxin enhancersStaphylococcus aureus (Th)TSST-1# Pyrogenic, decreases liver clearance of LPS# SuperantigenFever, increased susceptibility to LPS, rash, shock, capillary leakage Streptococcus pyogenes (Th)Exotoxin A, also called erythrogenic or pyrogenic toxinSimilar to TSST-1Fever, increased susceptibility to LPS, rash, shock, capillary leakage, cardiotoxicityCAMP inducersEnterotoxigenicEscherichia coli (-)Heat labile toxin (LT)LT stimulates an adenylate cyclase by ADP ribosylation of GTP-binding proteinBoth LT and ST promote secretion of fluid and electrolytes from intestinal epithelium Vibrio cholerae (-)Cholera toxinSimilar to E. coli LTProfuse, watery diarrhea Bacillus anthracisAnthrax toxin (3 proteins make 2 toxins)# EF = edema factor= adenylate cyclase# LF - lethal factor# PA = protective antigen (B component for both)# Decreased phagocytosis# Causes edema, kill cells Bordetella pertussis (Th)Pertussis toxinADP ribosylates GI, the negative regulator of adenylate cyclase, leading to increased cAMP# Histamine sensitizing# Lymphocytosis promotion# Islet activationCytolysinsClostridium perfringens (Th)Alpha toxinLecithinase# Damages cell membranes# Myonecrosis Staphylococcus aureus (Th)Alpha toxinPore formerMembrane becomes leaky
Scarlet fever
Pseudomonas infection
Acute meningococemia
Staphylococal disease
Infection