Gram Pos, gram neg, etc

Block 7 I&I Week 1

Diphtheria Toxin

Gram +, A-B Toxin, ADP-ribosylating A-B toxin inactivates elongation factor 2, addition of ADP-Ribose makes protein dysfunctional, pharyngeal damage

Pseudomonas Aeruginosa

Exotoxin A, ADP-ribosylating A-B toxin inactivates elongation factor 2, addition of ADP-ribose makes protein dysfunctional, wound infections, pneumonia, chronic infections in immunocompromised

Shiga Toxin

Gram neg, A-B Toxin, Binds 60s ribosome in cells, removes adenine residue from rRNA in 60S subunit, blocks protein synthesis, dysentery, invasion, and toxin cause bloody diarrhea, intestinal issues

Shiga-Like Toxin (E. Coli)

Gram neg, A-B Toxin, binds 60S ribosome in cells, removes adenine residue from rRNA in 60S subunit, blocks protein synthesis, foodborne outbreaks, bloody diarrhea, intestinal damage, hemolytic uremic syndrome (thrombocytopenia, anemia, renal dysfunction)

Staphylococcus aureus

Gram + cocci, TSST-1, TSS

Steptococcus pyogenes

Gram + cocci, pyrogenic exotoxin A, Strep TSS associated with necrotizing fascitits

Sta. Aureus

Gram + cocci, catalase pos, Coagulase pos, mannitol fermenter

Sta. Epidermidis

Gram + cocci, Catalase pos, Coagulase neg, mannitol non-fermenter, novobiocin sensitive S

Sta. Saprophyticus

Gram + cocci, Catalase pos, Coagulase neg, mannitorl non-fermenter, novobiocin resistant

Str. Agalactiae (GBS)

Gram + cocci, beta hemolytic, bacitracin resistant S

Str. Pyogenes

Gram + cocci, beta hemolytic, bacitracin sensitive

Str. Viridans

Gram + cocci, Alpha hemolytic, optochin resistant

Str. Pneumoniae

Gram + cocci, alpha hemolytic, optochin sensitive

enterococci

gamma hemolytic, bile and NaCl tolerant

St. gallolyticus/bovis

Gram + cocci, gamma hemolytic, bile tolerant NOT NaCl tolerant

Protein A

binds IgG Fc, prevents phagocytosis & complement activation

Exofoliation

exotoxin that blisters the skin, destroys keratinocytes attachments in stratum granulosum only, damage is interior dermal & heals with no scar E

Enterotoxin

massive, non-specific T-cell activation resulting in a “cytokin storm”

TSST

massive, non-specific T-cell activation resulting in a “coupling storm”

Methicilin-Resistant S. Aureus

resistant to all B lactam, alertness penicillin-binding protein (mecA gene codes of altered PDP - lowers affinity of binding proteins for drug)

Staphylococcal Food Poisoning

Preformed S. Aureus enterotoxins, rapid onset, N/V/D, no fever

Staphylococcal Toxin Shock Syndrome

Rapid onset, distributive shock (massive vasodilation from cytokine storm), blood cultures often negative (toxin mediated, not due to bacteremia), diffuse erythematous rash leading to desquamation, multi-system organ failure, classic associations = tampon use, wound packing, surgical sites, burns

Cellulitis

Str. Pyogenes rarely Sta. Aureus F

Folliculitis

Sta. Aureus

Furuncles

boil abscess, Sta. Aureus

Carbuncles

cluster of boil abscesses, Sta. Aureus

Impetigo

Sta. Aureus or Str. Pyogenes - honey crusted lesions near nose or mouth, colloid (big blisters) - exfoliating toxin, non-colloid (small blisters)

Scalded Skin Syndrome

Sta. Aureus exfoliation, Infants and children < 6 yrs old, skin sloughs off with gentle touch (Nikolsky’s sign)

Necrotizing Fascitis

Str. Pyogenes

Typical UTI?

Sta. Saprophyticus (Coag neg, nitrate neg), enterococcus (nitrate neg, catheter-associated), E. Coli (nitrate pos)

Acute endocarditis

Sta. Aureus targets healthy heart valves

Subacute endocarditis

Str. Viridans, history of prior valve abnormality is common

Untreated strep refuse causes

scarlet fever (strep throat w. “Sunburn” skin rash and strawberry tongue), rheumatic fever (ganache to joints/heart valves), glomerulonephritis, necrotizing fasciitis

Blood culture it’s for Str. Gallolyticus/bovis?

Normal gut flora, gamma hemolytic, grows in bile but not 6.5% NaCl, strongly associated with Colon Cancer

Common cause of pneumonia in adults and otitis media in children?

Str. Pneumonia, alpha hemolytic, IgA protease, Capsules (asplenic patients increased risk of sepsis)

Listoriosis

Gram pos rod, adults get it through cold food/unpasteurized cheese, or milk, undercooked meat and unwashed vegetables), neonates (transplacental or vaginal transmission - bacteremia and flu-like in 3rd trimester often spontaneous resolves, can cause fetal demise or newborn infection (stillborn or die soon after birth))

Corynebacterium diphtheria

Small, curved, gram pos rods, exotoxin inactivates elongation factors and inhibits protein synthesis, symptoms = sore throat, fever, lymphadenopathy, gray-white membrane in pharynx, myocarditis, CNS disease, renal disease

Nocardia

Gram Pos, catalase pos, branching filaments, obligate aerobe, partially acid-fast, pneumonia (immunocompromised) and skin infections (normal)

actinomyces

fungi-like with branching filaments, anaerobe, gram pos, pus contains “yellow sulfur granules”

anthrax-bacillus anthracis

gram pos rod, edema toxin (cAMP), lethal toxin - cleaves MPKK signaling pathway, ONLY BACTERIUM W PROTEIN CAPSULE (D-GLUTAMATE)

Bacilius cereus = “reheated rice syndrome”

gram pos rod, enterotoxins

botulism - clostridium botulinum

Gram pos rod, infant eats honey, adults eat canned foods that were contaminated, diplopia, dysphagia, dysphonia

clostridium tetani

gram pod rod, acts on inhibitory Renshaw cell interneurons, prevent GABA and glycine release, uncontrolled muscle contraction/tetany, lockjaw, arched back, diaphragm seizure

clostridium perfringens

gram pos rod, gas gangrene

clostridium difficile

gram it’s rod, toxin A = watery diarrhea, toxin B = cytotoxic causes cell necrosis/fibrin deposition, destroys cytoskeleton of GI cells

Klebsiella pneumoniae

gram neg rod, rapid lactose fermenter, non-motile, encapsulated, immunocompromised, CURRANT JELLY SPUTUM, aspiration pneumonia, abscess in lungs & livers, alcoholics, diabetes

E. Coli

gram neg rod, rapid lactose fermenter, fimbriae, capsule (K antigen - prevents phagocytosis and complement activation)

Enterobacter

gram neg rod, rapid lactose fermenter, resistant to many antibiotics, extended-spectrum beta lactamases (penicillin, cephlalosporin, aztreonam)

Citrobacter

gram neg rod, slow lactose fermenter

Serratia

gram neg rod, slow lactose fermenter, red colonies, catalase positive, may cause osteomyelitis in IV drug users

Pseudomonas aeruginosa

gram neg rod, obligate aerobe, non lactose fermenter, oxidase positive, resistant to many drugs, BE PSEUDO (burns, endocarditis, pneumonia, sepsis, external otitis, UTI, drug user, osteomyelitis), green grapes,

Proteus

gram neg rod, non lactose fermenter, oxidase negative, bulls-eye on blood agar plates, produces urease

Salmonella typhi

rose spots

Legionella

does not stain well, silver stain used, buffered charcoal yeast extract agar, inhalation of aerosolized bacteria - hotel air conditioning tanks

H. Pylori

gram neg rods, urease positive, motile, causes gastritis and peptic ulcer

Bacteriodes fragilis

gram neg obligate anaerobe, infection follows breach of mucosal barrier - part of polymicrobial GI infection: peritonitis, intra-abdominal scavengers, lung abscesses

S.typhi

gram neg rod, typhoid fever - rose spots, cervical motion tenderness, high risk of emotion pregnancy and infertility

N. Gonorrhea

Gram negative diplococci, gonococcus ferments only glucose, IgA Protease, sexually active young person with swollen painful knee, has no capsule, no maltose

N. Meningitidis

gram negative diplococci, meningococcus ferment glucose and maltose, meningococcus ferment glucose and maltose, IgA Protease

Chlamydia trachomatis

gram neg rods, visible via Wright-Giemsa stain, elementary body (small dense, enters cell via endocytosis, infectious), reticulate body (replicates in cells by fission, can be seen in tissue culture, diagnositics), Serotypes A-C: Infectious blindness, Serotypes D-K: sexually transmitted, urethritis/cervictis —> PID, newborns = neonatal conjunctivitis (similar to gonorrhea), Serotypes L1-L3: sexually transmitted, initially a genital ulcer —> tender inguinal or femoral lymph nodes. Classic Triad = arthritis, conjunctivitis, urethritis

Campylobacter

gram neg rods, animal GI flora, undercooked meat, unpasteurized milk, contaminated drinking water - presentation = acute diarrhea. COMMON TRIGGER OF GUILLAIN - BARRE SYNDROME

Vibrio cholera

gram neg rods, toxin carried by lysogenic bacteriophage, presentation = voluminous “rice-water” diarrhea, death from severe dehydration

Yersinia enterocolitica

gram neg rods, domesticated animals dogs, pigs (contaminated pork), contaminated water or milk, Presentation = fever, abdominal pain, nausea, vomiting, blood diarrhea, inflammation around pairs in that mimics Crohns or appendicitis

H. Influenzae type B

cherry red epiglottis, grows on blood agar with S. Aureus, otitis media is caused by unencapsulated H. Influenzae, vaccine contains capsular polysaccharide conjugates to protein carrier

Syphillis

painless chancre

H.ducreyi

painful chancroid

Bordetella pertussis

URI with sever coughing and the agar on which it is selectively grown, Regan-Lowe Charcoal Agar

Mycobacteria

Weakly staining GPR that contains mycolic acid, lipid rich cell wall that is “acid-fast”, stains Ziehl-Neelsen and Kinyoun

M.tuberculosis

Intracellular curved acid-fast rod, replicates in macrophages, spread via inhalation - forms granulomas, primary impacts lungs but can spread everywhere

M. Avium complex

Slow growing, acid-fast organisms, found in soil and water, disseminated disease HIV/AIDS, low CD4 counts <50, no lung findings in HIV/AIDS. If lung dividends —> it’s pulmonary TB. Slow growing - 7 days or more

M. Kansasii

most frequent non-TB mycobacteria after MAC, similar pathology to TB - but less virulent

M. Leprae

Obligate intracellular organism, grows very slowly (3-6 years incubation), grows best at cooler skin temps, reservoir is armadillos, not cultureable, infects skin and superficial nerves, skin lesions and loss of sensation

Tuberculoid Leprosy

Patches of hypopigmented skin, loss of sensation over affected area, Robust cell-mediated Th1 responses contains infection, lesions contain few bacteria and form granulomas

Lepromatous Leprosy

diffuse skin lesions - deformed and thickened, hypopigmentation and hair loss, severe neuropathy, Th2 response - humoral immunity, weakened cell-mediated immunity, antibodies can’t reach intracellular bacteria, lesions contain many bacteria and no granulomas