Microbiology Flashcards
Gram positive structure
Cell wall present; major surface antigen
Composition:
- Peptidoglycan
- Lipoteichoic acid–> TNF, IL-1 induction
Gram negative structure
No cell wall, only outer membrane
- Site of Endotoxin= LPS (lipopolysaccharide)= major surface antigen
Composition:
- Lipid A–> activate macrophages–> increased TNF and IL-1
- Antigen= O polysaccharide
- Periplasm= space between cytoplasmic membrane and outer membrane; contains hydrolytic enzymes (beta-lactamases)
Spore structure
Resistant to dehydration, heat, chemicals
- Must autoclave (121 C for 15 min)
Composition:
- Keratin-like coat
- Dipicolinic acid core
- Peptidoglycan
Seen in:
- Soil: B. anthracis, Clostridium perfringens, c. tetani
- Other: B. cereus, C. botulinum, Coxiella burnetti
Gram-positive cocci
Staphylococcus
Streptococcus
Gram-negative cocci
Neisseria
Gram-positive rod
Clostridium Corynebacterium Bacillus Listeria Mycobacterium (high lipid= acid fast) Gardenerella (gram variable)
Gram-negative rods
Almost everything else:
- Enterics:
- E. Coli
- Shigella
- Yersinia
- Klebsiella
- Proteus
- Enterobacter
- Serratia
- Vibrio
- Campylobacter
- Helicobacter (silver stain+)
- Pseudomonas
- Bacteroides - Respiratory:
- Haemophilus (pleomorphic)
- Legionella (intracellular; silver stain +)
- Bordetella - Zoonotic
- Francisella
- Brucella
- Pasteurella
- Bartonella
- resistant to Penicillin G (gram-negative outer membrane inhibits Pen G/Vanco from entering)
- Susceptible to Ampicillin, amoxicillin
Spirochetes
Gram-negative (too thin)
- Leptospira
- Borrelia
- Treponema
Pleomorphic bacteria
Giemsa-stain
- Rickettsiae (intracellular)
- Chlamydiae (intracellular, no muramic acid)
Bacteria with no cell wall
Mycoplasma= no staining
- Sterols with no wall
Giemsa-positive
Certain Bugs Really Try my Patience:
- Chlamydia
- Borrelia
- Rickettsiae
- Trypanosomes
- Plasmodium
Carbol Fuschin stain (Ziehl-Neelsen)
Acid-fast organisms
- Nocardia
- Mycobacterium
India ink positive
Cryptococcus neoformans
- can also stain with mucicarmine
Exotoxin
Derived from gram + and gram -
- Secreted from cell
- Polypeptide
- Located on plasmid/bacteriophage
- Highly toxic
- Antigenic= Induces antitoxins (titer antibodies)
- Vaccine= toxoids
- Destroyed at 60C (besides staph enterotoxin)
Seen in: Tetanus, botulism, diphtheria
Endotoxin
LPS= structural component of outer cell membrane in gram negative; released when lysed (NOT secreted)
Activates:
- Macrophages:
- IL-1–> fever
- TNF–> fever, hypotension
- NO–> hypotension - Complement
- C3a–> hypotension, edema
- C5a–> neutrophil chemotaxis - Tissue factor
- Coagulation cascade–> DIC
- Located on Bacterial chromosome
- Low toxicity
- Causes: Fever, shock
- Mode of action:Induces TNF and IL-l
- Antigenic: Poorly antigenic
- Vaccines= none
- Stable at 100C for 1 hour
Seen in: meningococcemia, gram-negative sepsis
Obligate aerobes
Nagging Pests Must Breathe
- Nocardia
- Pseudomonas aeruginosa
- Mycobacterium tuberculosis (apices of lung)
- Bacillus
Obligate anaerobes
Can’t Breathe Air
- Clostridium
- Bacteroides
- Actinomyces
Seen in GI tract, pathogenic anywhere else
** Can’t treat with aminoglycosides= need O2 to enter cell
Obligate intracellulars
Rickettsia
Chlamydia
Facultative intracellular
Now Listen Sally, Yer Friend Bruce Must Leave
- Neisseria
- Listeria
- Salmonella
- Yersinia Pestis
- Francisella
- Brucella
- Mycobacterium
- Legionella
Encapsulated bacteria
Positive Quellung reaction–> swelling
SHiNE SKiS
- Streptococcus pneumoniae
- Haemophilus infiuenzae type B
- Neisseria meningitidis
- Escherichia coli
- Salmonella
- Klebsiella pneumoniae
- group B Strep.
Catalase-positive
Degrades H2O2 before converted to microbicidal products by Myeloperoxidase (MPO) PLACESS for your cats: - Pseudomonas - Listeria - Aspergillus - Candida - E. Coli - S. Aureus - Serratia
Urease-positive
CHuck norris hates PUNKSS:
- Cryptococcus
- H. pylori
- Proteus
- Ureaplasma
- Nocardia
- Klebsiella
- S. epidermidis
- S. saprophyticus
IgA protease
Enzyme cleaving IgA–> colonize respiratory mucosa: SHiN
- S. pneumoniae
- H. influenza (B)
- Neisseria
** These can all take up naked DNA from environment as well= Transformation
Protein A
S. Aureus
- Binds Fc region of Ig–> no opsonization/phagocytosis
M Protein
Group A strep
- Prevents phagocytosis
Pigment-producing bacteria
Actinomyces Israelii= yellow (Israel= yellow sand)
S. Aureus= yellow (pus/gold)
Pseudomonas aeruginosa= blue/green (pyocyanin)
Serratia marcescens= red (maraschino cherry)
Novobicin
Used to ID catalase-positive, coagulase-negative staphylococci
- Staph Saprophyticus= resistant
- Staph Epidermis= sensitive
Optochin
used to ID catalase-negative alpha-hemolytic streptococci:
- Viridans= resistant
- Penumoniae= sensitive
Bacitracin
Used to ID Catalse-negative, beta-hemolytic streptococci:
- Agalactiae= resistant
- Pyogenes= sensitive
Alpha-hemolytic bacteria
Partial hemolysis; green ring around colonies
- Strep pneumo
- Strep viridans
Beta-hemolytic bacteria
Complete hemolysis; clear ring around colonies:
- Staph aureus
- Strep pyogenes (group A)
- Strep agalctiae (group B)
- Listeria monocytogenes
Staphylococcus aureus
Gram positive cocci, Clustered
Catalase positive
Coagulase positive
Virulence factor= Protein A (binds Fc-IgG–> prevents phagocytosis)
Causes:
- Inflammatory disease: skin infections, organ abscesses, pneumonia
- Acute bacterial endocarditis
- Osteomyelitis - Toxin-mediated disease:
- Toxic shock syndrome (TSST-1)= superantigen, binds MHC II receptor–> T-cell activation–> IFN-gamma, IL-2 release
- scalded skin (exfoliative toxin)
- rapid-onset food poisoning (preformed enterotoxins)
* * Activates T-cells (IL-2) and macrophages (IL-1, TNF) - MRSA: resistant to beta-lactams (altered penicillin-binding protein)
Treatment:
- Nafcillin (Naf for Staph- EXCEPT MRSA)
- Vancomycin for MRSA
THINK:
- Pus, empyema, abscess
- Surgical wound
- chronic granulomatous disease (Catalase-positive microbes)
Staphylococcus epidermidis
Gram positive cocci
Catalase positive
Coagulase negative
Novobicin sensitive (vs staph saprophyticus)
Infects prostehetic devices, IV catheters (biofilm)
- Seen in normal skin flora
- Contaminates blood cultures
Resistant to penicillins, tx with Vancomycin
Staphylococcus saprophyticus
Gram positive cocci
Catalase positive
Coagulase negative
Novobicin resistant (vs staph epidermidis)
Causes UTIs
Streptococcus pneumoniae
Gram positive cocci; lancet shaped Catalase negative alpha-hemolytic Capsule (+ quelling) Optochin sensitive (vs strep Viridans) IgA protease
Causes:
- Meningitis
- Otitis media
- Pneumonia (rusty sputum)
- Sinusitis
- Sepsis, splenectomy in Sickle cell
Streptococcus viridans
Gram positive cocci Catalase negative alpha-hemolytic No capsule Optochin resistant (vs strep pneumo)
Causes:
- Dental caries (normal flora in mouth= strep mutans)
- Subacute bacterial endocarditis (strep sanguis)
Strep pyogenes
Group A strep Gram positive cocci Catalase negative beta-hemolytic Bacitracin sensitive (vs strep agalactiae)
M-protein (prevents opsonization–> blocking phagocytosis)
Exotoxin=
- streptolysin O
- Protein degrades cell membrane (lyse RBCs)- test for ASO antibodies - Exotoxin A: brings MHC II and T-cell receptors together–> release IFN-gamma, IL-2 release–> Toxic shock-like syndrome
- Streptokinase= plasminogen activator (blocks clotting)
Causes:
- Pyogenic:
- Pharyngitis
- Cellulitis
- Impetigo (precedes glomerulonephritis, pharyngitis) - Toxigenic:
- Scarlet fever (spares face, strawberry tongue, throat)
- Toxic shock-like syndrome
- Necrotizing fasciitis - Immunologic:
- Rheumatic fever (polyarthritis, carditis, subcutaneous nodules, erythema marginatum, Sydenham’s chorea)
- Acute glomerulonephritis
- Post strep glomerulonephritis= deficiency of complement due to fixation in renal tubules
- ASO titer to detect infection (antibodies to streptolysin O)
- Host antibodies to M-protein–> rheumatic fever
Strep agalactiae
Group B strep Gram positive coci Catalase negative Beta hemolytic (Produces CAMP factor--> increased hemolysis) Bacitracin resistant (vs strep pyogenes) Hippurate test positive
Causes:
- Illnesses mainly seen in babies (due to colonization of vaginal flora): Pneumonia, meningitis, sepsis
- Screen women at 35-37 weeks
- Prophylaxis with penicillin
Enterococci
Group D strep Gram positive cocci Catalase negative Non-hemolytic/variable hemolysis Grows in Bile and 6.5% NaCl
Enterococci faecalis, faecium:
- Penicillin G resistant
- Cause UTI, biliary tract infections, subacute endocarditis
- Vancomycin-resistant strains= nosocomial infection
Streptococcus bovis
Group D strep Gram positive cocci Catalase negative Non-hemolytic Grows in Bile (no NaCl)
Colonizes gut
- Colon cancer patients: subacute endocarditis, bacteremia
Corynebacterium diphtheriae
Gram positive rod (club-shaped)
Black colonies in cystine-tellurite agar
Metachromatic (blue and red) granules
AB Exotoxin= (B=binds, A= active–> EF-2)
- B-prophage encoded–> inhibits protein synthesis (ADP-ribosylates elongation factor= EF-2)
- Test= Elek’s test
Causes:
- Pseudomembranous pharyngitis (gray-white)
- Lymphadenopathy
- Myocarditis
- Arrhythmias
** Toxoid vaccine= induces production of IgG against exotoxin B (toxin causes disease, not bacteria)
Clostridium tetani
Gram-positive rod
Spore-forming
Obligate anaerobe
Exotoxin= Tetanospasmin
- Tetanus toxin–> cleaves neurotransmitter-releasing proteins (SNARE)
- Blocks glycine, GABA release (inhibitory neurotransmitters) from Renshaw cells in spinal cord
- Causes spastic paralysis, trismus (lockjaw), risus sardonicus)
Tx: passive vaccine
Clostridium botulinum
Gram-positive rod
Spore-forming
Obligate anaerobe
Exotoxin= botulinum toxin
- Cleaves SNARE proteins (blocking neurotransmitter release)
- Inhibits ACh release at NM junction–> flaccid paralysis
- Adults= ingest preformed toxin
- Babies= spores in honey–> floppy baby)
Tx: passive vaccine
Clostridium perfringens
Gram-positive rod
Spore-forming
Obligate anaerobe
Exotoxin= alpha toxin (lecithinase= phospholipase)
- Phospholipase degrades tissue, cell membranes–>
- Causes myonecrosis (gas gangrene)
- Hemolysis
Clostridium difficile
Gram-positive rod
Spore-forming
Obligate anaerobe
Exotoxins:
- Toxin A = enterotoxin binding brushborder of gut)
- Toxin B = cytotoxin binding enterocytes–> pseudomembranous colitis
- Secondary to antibiotics (clindamycin, ampicillin)
Treatment:
- Metronidazole
- Oral vancomycin
Bacillus anthracis
Gram-positive rod
* Polypeptide capsule (D-glutamate containing)
Spore-forming
Exotoxin= anthrax (Edema factor)
- Mimics adenylate cyclase (increased cAMP)
- Calmodulin-dependent adenylate cyclase–> increases cAMP in smooth muscle–> vasodilation (edema), suppressed neutrophil funciton)
Forms:
- Cutaneous–> black eschar (painless ulcer)–> bacteremia, death)
- Pulmonary–> flu-like symptoms–> fever, pulmonary hemorrhage, mediastinitis, shock (Woolsorter’s disease)
Bacillus cereus
Gram-positive rod
Spore-forming
Obligate aerobe
Enterotoxin= Cereulide
- Food poisoning (enterotoxin in rice= “reheated rice syndrome)
- Emesis: rice, pasta–> N/V in 1-5 hours
- Diarrhea: GI pain, watery, non-bloody in 8-18 hours
Listeria Monocytogenes
Gram positive rod
Facultative intracellular
Catalase positive
Beta hemolytic
Forms “actin rockets”–> move cell to cell
- Tumbling motility
Ingested from unpasteurized milk/cheese, deli meats
Causes:
- Amnionitis
- Septicemia
- Spontaneous abortion
- Meningitis in immunocompromised
- Gastroenteritis in healthy (self-limited)
Vaginal transmission
Causes:
- Granulomatosis infantiseptica
- Neonatal meningitis
- Tx= ampicillin
Actinomyces
Long, branching filament (resembles fungi) Gram-positive Anaerobe NOT acid-fast Found in normal oral flora
Causes:
- Oral/facial abscesses that drain–> sinus tracts
- Yellow “sulfur granules”
Tx: Penicillin
Nocardia
Long, branching filament (resembles fungi) Gram-positive Aerobe Acid fast Found in soil
Causes:
- Pulmonary infections in immunocompromised
- Cutaneous infections (post-trauma) in healthy
Tx: Sulfonamides
Mycobacterium tuberculosis
Gram-positive rod
Carbol-Fuschin (Ziehl-Neelsen) stain
Acid fast (lipid membrane)
Obligate aerobe (lung apices)
Facultative intracellular
* Cord factor in virulent strain–> TNF-alpha release, inhibited macrophage maturation
* Sulfatides (surface glycolipids) inhibit phagolysosomal fusion
Primary TB:
- Nonimmune host infected–> Ghon complex:
1. Heals (fibrosis)–> immunity/hypersensitivity
2. Progressive lung disease (immune compromised)
3. Severe bacteremia–> Miliary TB
4. Preallergic lymphatic/hematogenous dissemination–> dormant–> reactivate later in life
Secondary TB:
- Partially immune hypersensitized host (adult) reinfected)
1. Fibrocaseous cavitary lesion (upper lobes)
2. Reactivates
Reactivated TB= Extrapulmonary TB
- CNS (parenchymal TB/meningitis in base of brain)
- Vertebral body (Pott’s disease)
- Lymphadenitis
- Renal
- GI
Symptoms:
- Fever, night sweats, weight loss, hemoptysis
Tx:
- Prophylaxis= Isoniazid (INH)
- Therapy= Rifampin, Isoniazid, Pyrazinamide, Ethambutol (RIPE for tx)
Mycobacteria Kansasii
Gram-positive rod
Carbol-Fuschin (Ziehl-Neelsen) stain
Acid fast (lipid membrane)
Obligate aerobe (lung apices)
Facultative intracellular
* Cord factor in virulent strain–> TNF-alpha release, inhibited macrophage maturation
* Sulfatides (surface glycolipids) inhibit phagolysosomal fusion
Pulmonary TB-like symptoms
Mycobacterium avium-intracellulare
Gram-positive rod
Carbol-Fuschin (Ziehl-Neelsen) stain
Acid fast (lipid membrane)
Obligate aerobe (lung apices)
Facultative intracellular
* Cord factor in virulent strain–> TNF-alpha release, inhibited macrophage maturation
* Sulfatides (surface glycolipids) inhibit phagolysosomal fusion
Disseminated non-TB disease in AIDS, resistant to multiple drugs
** Prophylaxis with azithromycin (CD4+ < 50)
Tx: Azithromycin, Rifampin, Ethambutol, Streptomycin
Mycobacterium leprae
Gram-positive rod
Carbol-Fuschin (Ziehl-Neelsen) stain
Acid fast (lipid membrane)
Obligate aerobe (lung apices), likes cool temps
Facultative intracellular
* Cord factor in virulent strain–> TNF-alpha release, inhibited macrophage maturation
* Sulfatides (surface glycolipids) inhibit phagolysosomal fusion
Reservoir in USA= armadillos
Causes Leprosy. 2 forms:
1. Lepromatous= lethal
- Communicable
- Low cell-mediated immunity, humoral Th2 response only
Tx: Dapsone, rifampin, clofazimine (2-5 years)
- Tuberculoid= hypoesthetic hairless skin plaques (“glove and stocking” loss of sensation)
Tx: Dapsone, Rifampin (6 months)
Lactose-fermenting enteric bacteria
Gram-negative rods
Grow pink colonies on MacConkey’s agar:
Fast fermenter= Lactose in KEE
- Klebsiella
- E. coli
- Enterobacter
Slow fermenter=
- Citrobacter
- Serratia
Neisseria Gonococci
Gram-negative diplococci
Ferments Glucose (Gonococci)
Produces IgA proteases
Facultative intracellular
Grown on special agar: Thayer-Martin agar (or VPN agar)—an agar plate containing antibiotics (vancomycin, colistin, nystatin, and TMP-SMX)
- NO vaccine available (rapid antigenic variation in pilus)
- STD
Causes:
- Septic arthritis
- Neonatal conjunctivitis
- PID
- Fitz-Hugh-Curtis syndrome (adhesions due to PID; infection of liver capsule)
Tx: Ceftriaxone (+ azithromycin/doxycyclin for chlamydia coinfection)
Neisseria Meningococci
Gram-negative diplococci Ferments Maltose and glucose (MeninGococci) Produces IgA proteases Facultative intracellular Encapsulated (polysaccharide capsule)
Grown on special agar: Thayer-Martin agar (or VPN agar)—an agar plate containing antibiotics (vancomycin, colistin, nystatin, and TMP-SMX)
- Vaccine (none for Type B)
- Found in respiratory, oral secretions
Causes:
- Meningococcemia
- Meningitis
- Waterhouse-Friderichsen syndrom
Tx: Ceftriaxone, Pen G
** Rifampin, ciprofloxacin, ceftriaxone in close contacts
Haemophilus Influenza
Gram negative Coccoid rods Requires factor V and X to grow in culture (chocolate agar) IgA protease Encapsulated
- Vaccine= type B capsular polysaccharide conjugated to diphtheria toxoid (2-18 months)
- Nontypable strains cause mucosal infections (no vaccine available)
Causes:
- Epiglottitis (cherry red)
- Meningitis
- Otitis media
- Pneumonia
Tx: Ceftriaxone (meningitis)
* Rifampin prophylaxis in close contacts
THINK:
- Pediatric infection (epiglottitis)
Legionella pneumophilia
Gram-negative rod
Facultative intracellular
Silver stain
Grown on charcoal yeast extract with iron, cysteine
- Aerosol transmission from water source
- Detected in urine
- Labs show hyponatremia
Causes:
- Legionnaire’s disease= severe pneumonia, fever, GI, CNS symptoms
- Pontiac fever= mild flu-like syndrome
Tx: Macrolide (protein synthesis), quinolone (topoisomerase II)
Pseudomonas aeruginosa
Gram negative rod (enteric) Obligate aerobe Catalase positive Lactase NON-fermenting Oxidase positive Blue-green pigment, grape-like odor
Motile, oxidase positive
Produces:
- Endotoxin (fever, shock)
- Exotoxin A (inactivates EF-2)
- Elastase (breaks down vessel walls)
Causes: PSEUDOmonas - Pneumonia (chronic in CF pts due to biofilm) - Sepsis - External otitis - UTI - Drug use - Osteomyelitis (diabetic/drug user) \+ Hot tub foliculitis, wound/burn infections \+ MEO in diabetics
Tx:
- Aminoglycoside + extended-spectrum penicillin (piperacillin, ticarcillin)
Enteroinvasive E. Coli (EIEC)
Gram-negative rod
Lactose fermenting
Virulence factors:
- P fimbriae (cystitis/pyelonephritis)
- K capsule (pneumonia, neonatal meningitis)
- LPS endotoxin (septic shock)
Mechanism:
- Invades intestinal mucosa–> necrosis, inflammation
Manifestation: similar to Shigella
- Invasive
- Dysentery (blood, pus in stool)
Enterotoxigenic E. Coli (ETEC)
Gram-negative rod
Lactose fermenting
Virulence factors:
- P fimbriae (cystitis/pyelonephritis)
- K capsule (pneumonia, neonatal meningitis)
- LPS endotoxin (septic shock)
Mechanism:
- Labile toxin: overactivates adenylate cyclase–> increased cAMP–> Cl- secretion in gut–> H20 moves out of cells
- Stable toxin: overactivates guanylate cyclase–> increased cGMP–> decreased resorption of NaCl /H20 in gut
- NO inflammation/invasion
Manifestation: traveler’s diarrhea
Enteropathogenic E. Coli (EPEC)
Gram-negative rod
Lactose fermenting
Virulence factors:
- P fimbriae (cystitis/pyelonephritis)
- K capsule (pneumonia, neonatal meningitis)
- LPS endotoxin (septic shock)
Mechanism:
- Adheres to apical surface, flattens villi
- Prevents absorption
Manifestation:
- Pediatric diarrhea
Enterohemorrhagic E. Coli (EHEC)
Gram-negative rod
Lactose fermenting
Virulence factors:
- P fimbriae (cystitis/pyelonephritis)
- K-1 capsule (pneumonia, neonatal meningitis)
- LPS endotoxin (septic shock)
Mechanism:
- O157:H7= most common–> Shiga-like toxin
- Shiga-like toxin (SLT)= inactivates 60S ribosomal subunit by removing adenine from rRNA
- Endothelial swelling, narrowed lumen–> hemolysis, reduced renal blood flow
- Damaged endothelium–> thrombocytopenia
Cuases:
- Dysentery (Shiga-like)
- Hemolytic-uremic syndrome (HUS) due to cytokine release in response to SLT–> vascular damage–> capillary thrombus formation–> anemia, thrombocytopenia, acute renal failure, increased bleeding time
Klebsiella
Gram negative rod
Lactose fermenter
Polysaccharide capsule (mucoid colonies)
4As:
- Aspiration pneumonia
- Abscess (lungs/liver)
- Alcoholics
- diAbetics
- can also cause nosocomial UTI: positive urease test
Salmonella
Gram negative rod Lactose non-fermenter Oxidase negative Facultative intracellular Encapsulated
- Flagellated
- Hematogenous dissemination
- Animal reservoir
- Produce hydrogen sulfide
- Invades intestinal mucosa–> monocytic response
Causes:
- Bloody diarrhea
- Non-typhoidal= appendicitis mimicker
- Typhi= Typhoid fever (humans only): rose spots on abdomen, fever, headache, diarrhea
- Osteomyelitis in sickle cell pts
Tx: Antibiotics prolong symptoms
Shigella
Gram negative rod
Lactose non-fermenter
Oxidase negative
Shiga toxin= inactivates 60S ribosomal subunit by removing adenine from rRNA
- No flagella
- Cell to cell transmission
- Reservoir= humans/primates
- Invades intestinal mucosa–> PMN infiltration
- Shiga toxin–> Cytokine release–> HUS: due to cytokine release in response to Shige toxin–> vascular damage–> capillary thrombus formation–> anemia, thrombocytopenia, acute renal failure, increased bleeding time
Tx: antibiotics shortens excretion of organism in feces
Campylobacter jejuni
Gram negative comma-shaped
Oxidase positive
Grows at 42C
Transmitted through poultry, meat, unpasteurized milk
Causes:
- Bloody diarrhea (esp. children)
- Guillain-Barre syndrome, reactive arthritis
- Mimics appendicitis
Vibrio cholerae
Gram negative comma-shaped
Oxidase positive
Grows in alkaline media
Mechanism:
- Cholera toxin Activates Gs of adenylate cyclase–> increased cAMP–> increased Cl- secretion, H20 efflux
Causes:
- Profuse rice-water diarrhea (common in developing countries)
Tx: rehydration
Yersinia enterocolitica
Gram negative rod
Facultative intracellular
Mechanism:
- Transmitted from pet feces, contaminated milk, pork
Causes:
- Mesenteric adentitis (Crohn’s, appendicitis mimicker)
H. Pylori
Curved Gram-negative rod
Silver stain
Urease positive (urease breath test)- alkaline environment created in stomach
Causes:
- Gastritis
- 90% duodenal ulcers
- Increased peptic ulcer, gastric adenocarcinoma, B-cell lymphoma risk
Tx: triple therapy:
- PPI
- Clarithromycin
- Amoxicillin/ Metronidazole
Spirochetes
Borrelia (BIG)= Wright/Giemsa stain
Leptospira
Treponema= dark field microscopy
Leptospira interrogans
Spirochete
Water contaminated with animal urine (triathletes in tropics)
Causes:
- Flu-like symptoms
- Jaundice
- Photophobia with conjunctivitis
- Weil’s disease= icterohemorrhagic leptospirosis: severe; jaundice, azotemia (liver, kidney dysfunction), fever, hemorrhage, anemia
Borrelia Burgdorferi
Spirochete (visualized with Wright/Giemsa stain)
Lyme disease:
- Transmitted by Ixodes tick
- Reservoir= wood mouse
- Stages:
1. Erythemia migrans (bull’s eye), flu-like
2. Neurologic (Bell’s palsy), cardiac (AV node block)
3. Musculoskeletal (chronic monoarthritis, migratory polyarthritis), neurological (encephalopathy, polyneuropathy), cutaneous
Treponema Pallidum
Spirochete
- Visualized by dark-field microscopy
- Screened with VDRL, confirmed with FTA-ABS
Syphillis:
- Primary: localized painless chancre (treponemes)
- Secondary: disseminated disease
- Constitutional symptoms
- Maculopapular rash
- Condylomata lata (treponemes found on warty lesions) - Tertiary:
- Gummas (chronic granulomas)
- Aortitis (vaso vasorum destruction)
- Neurosyphilis (tabes dorsalis)
- Argyll-Robertson pupil (non-reactive, accomodative)
- Signs: broad-based ataxia, + Romberg, Charcot joint, stroke w/o HTN
- Treponemes in spinal tap
Congenital syphilis:
- Saber shins
- Sadle nose
- CNVII deafness
- Hutchinson’s teeth
- Mulberry molars
- VDRL= nonspecific; can also indicate:
- Viruses
- Drugs
- Rheumatic fever
- Lupus, leprosy
Tx: Pen G
- Can lead to Jarisch-Herxheimer reaction (killed bacteria release pyrogens)- administer steroids, low dose antibiotics
Bartonella
Cat scratch disease
- Can cause bacillary angiomatosis in immune compromised
Borrelia Recurrentis
Recurrent fever
Source: Louse
Brucella
Gram negative rod
Facultative intracellular
Causes: Undulent fever
Source: unpasturized dairy
Chlamydia psittaci
Obligate intracellular organism (cannot make own ATP)
- Giemsa positive
- Pleomorphic
Elementary body= Enters cell via Endocytosis
Reticulate body= replicates in cell via fission (seen on tissue culture)
- Cytoplasmic inclusions on Giemsa, fluorescent antibody
Psittacosis (pneumonia)
Source: parrots, birds
Tx:
- Azithromycin (one time)
- Doxycycline
Coxiella burnetii
Q fever
Source: aerosol of cattle, sheep amniotic fluid
- Survives in soil for years (spore)
Tx: Doxycycline
Ehrlichia chaffeensis
Monocyte with morula (berry-like) inclusion in cytoplams
Ehrlichiosis
Source: lone star tick
Tx: Doxycycline
Francisella tularensis
Tularemia
Source: ticks, rabbits, deer fly
Pasteurella multocida
Cellulitis, osteomyelitis
Source: animal bite (cat, dog)
Rickettsia prowazekii
Obligate intracellular
Need CoA and NAD+
Epidemic typhus (pro-WAr) - Rash sparing palms and soles
Source: louse
Tx: Doxycycline
Rickettsia Typhi
Obligate intracellular
Need CoA and NAD+
Endemic typhus
Source: fleas
Tx: Doxycycline
Yersinia pestis
Facultative intracellular
Plague
Source: fleas (rats/prairie dogs= reservoir)
Gardenerella vaginalis
Gram-variable pleomorphic rod
“Clue cells” on vaginal swab
KOH prep= fishy smell
Causes: Bacterial vaginitis
- Non-painful, smelly
- Not STD (associated with sexual activity)
Tx: Metronidazole
Rickettsia Rickettsii
Obligate intracellular
Need CoA and NAD+
Causes:
- Rocky Mountain Spotted Fever (Broad distribution)
- Rash: wrists, ankles–> trunks, palms, soles
- Headache, fever
Anaplasma
Anaplasmosis:
Granulocytes with morula in cytoplasm
Chlamydia trachomatis
Obligate intracellular organism (cannot make own ATP)
- Giemsa positive
- Pleomorphic
Elementary body= Enters cell via Endocytosis
Reticulate body= replicates in cell via fission (seen on tissue culture)
- Cytoplasmic inclusions on Giemsa, fluorescent antibody
Causes: Reiter's syndrome: - Reactive arthritis - Conjunctivitis - Nongonococcal urethritis - PID
Serotypes:
- A, B, C= chronic infection–> follicular conjuntivitis–> blindness (ABC= Africa, Blindness, Chronic infection)
- D-K= Urethritis/PID, ectopic pregnancy, neonatal pneumonia (staccato cough), neonatal conjunctivitis)
- L1, L2, L3= lymphogranuloma
Tx:
- Azithromycin (one time)
- Doxycycline
Mycoplasma pneumoniae
No cell wall (no stain)
- Sterol membrane (stability)
Atypical “walking” pneumonia
- Insidious onset, H/A, nonproductive cough, diffuse interstital infiltrate
- IgM titer–> agglutinate, lyse RBCs
Tx: macrolide, fluoroquinolone
Bordetella pertussis
Pertussis toxin
- Overactivates adenylate cyclase–> increased cAMP (disables Gi)–> impairs microbial phagocytsosis
Causes:
- Whooping cough= cough on expiration, whoop on inspiration
Histoplasmosis
Dimorphic fungi (20C= cold mold, 37C= heat yeast) - Can mimic TB with no person-person transmission
Location:
- Mississippi, Ohio river valleys
- Bird/bat droppings in CAVES
Causes: pneumonia
- Hilar adenopathy
Histo: Macrophage filled with histo (Histo hides in macrophages)
Tx:
- Local= fluconazole, itraconazole
- Systemic= Amphotericin B
Blastomycosis
Dimorphic fungi (20C= cold mold, 37C= heat yeast) - Can mimic TB with no person-person transmission
Location:
- States East of Mississippi river, Central America
Causes: inflammatory, lung disease
- Disseminates to skin, bone
- Granulomatous nodules
Histo: broad-based budding (Blasto Buds)
Tx:
- Local= fluconazole, itraconazole
- Systemic= Amphotericin B
Coccidioidomycosis
Dimorphic fungi (20C= cold mold, 37C= heat SPHERULE) - Can mimic TB with no person-person transmission
Location:
- SW USA, California (Valley fever)
Causes: pneumonia, meningitis
- Disseminate to skin, bone
- Increased cases after earthquakes
Histo: Spherule filled with endospores (larger than RBC)
- Coccidio crowds
Tx:
- Local= fluconazole, itraconazole
- Systemic= Amphotericin B
Paracoccidioidomycosis
Dimorphic fungi (20C= cold mold, 37C= heat yeast) - Can mimic TB with no person-person transmission
Location: Latin America (Paracoccdio parasails with Captain’s wheel all the way to Latin America)
Histo:
- Budding yeast, captain’s wheel formation
Tx:
- Local= fluconazole, itraconazole
- Systemic= Amphotericin B
Tinea Versicolor
Malassezia furfur
- Lipid degradation–> acids–> malanocyte damage–> hypo/hyperpigmented areas
- Seen in hot, humid weather
Histo:
- “spaghetti and meatball” on KOH
Tx:
- Topical miconazole
- Selenium sulfide (Selsun Blue)
Candida albicans
Tx:
- Topical azole for vaginal infection
- Fluconazole/capsofungin for oral/esophageal
- Fluconazole, ampho B, caspofungin for systemic tx
Aspergillus Fumigatus
Invasive= immunocompromised, chronic granulomatous disease
Allergic broncopulmonary (ABPA)= Asthma, CF
Aspergillomas in lung cavities (post-TB)
** Produce aflatoxins= associated with Hepatocellular carcinoma
Cryptococcus neoformans
Encapsulated (crypt) yeast
- Found in soil, pigeon droppings
- Inhaled, hematogenous dissemination to meninges
Culture:
- Sabouraud’s agar
- India Ink stain
- Latex agglutination= polysaccharide capsular antigen
Can cause meningitis (“soap bubble lesions” in brain) in immune-compromised (AIDS patients with CD4+ < 50)
Tx:
- Amphotericin B + Flucytosine
Pneuomcystis jirovecii
PCP= diffuse interstitial pneumonia
- bilateral CXR
- Dx= biopsy, lavage
- Disc-shaped yeast on methenamine silver stain
Tx: TMP-SMZ, pentamidine, dapsone
- Prophylax with CD4+ < 200
Sporothrix schenckii
Dimorphic
Cigar-shpaed budding yeast
“Rose-pickers” thumb= pustule, ulcer with nodules along lymphatic drainage
Tx: itraconazole, potassium iodide (plant a rose in the pot)
Giardia Lamblia
Trophozoite
Giardiasis: bloating, flatulence, foul-smelling, fatty diarrhea
Transmission: cysts in water
Dx: stool: trophozoites, cysts
Tx: Metronidazole (GET on the Metro: G= giardia, E= entamoeba, T= Trichomonas)
Entamoeba histolytica
Trophozoite
Amebiasis: bloody diarrhea (dysentery), liver abscess (anchovy paste exudate), RUQ pain (flask-shped ulcer if submucosal colon abscess ruptures)
Transmission: cysts in water
Dx: Serology, trophozoites (with phagocytosed RBCs) or cysts (multinucleated) in stool
Tx: Metronidazole (GET on the Metro: G= giardia, E= entamoeba, T= Trichomonas)
- Iodoquinol for asymptomatic carriers
Cryptosporidium
AIDS patients: severe diarrhea
- Milder (watery diarrhea) in immunocompetent
Transmission: Cysts in water)
Dx: Cysts on acid-fast stain
Tx: Prevent (filter water)
- Nitazoxamide in immunocompetent
Toxoplasma Gondii
HIV: brain abscess (ring-enhancing lesions)
Congenital: Triad= chorioretinitis, hydrocephalus, intracranial calcifications
Transmission: cysts in meat, cat feces
Dx: Serology, biopsy
Tx: Sulfadiazine, pyrimethamine
Naegleria Fowleri
Rapidly fatal meningoencephalitis
Transmission: swimming in freshwater lakes, Netti pot (cribiform plate–> brain)
Dx: Amoebas in CSF
Tx: Amphotercin (maybe?)
Trypanosoma brucei gambiense
West African Sleeping sickness:
- Slowly progressive fevers, wasting, late neuro symptoms
- Recurrent fevers: due to Variable Surface Glycoproteins (change with each generation–> immune system can’t keep up)
Transmission: Tsetse fly (painful bite)
Diagnosis: blood smear
Tx:
Blood borne= Suramin
CNS= Melarsoprol
“Sure is nice to go to sleep. Melatonin helps with sleep”
Trypanosoma brucei rhodesiense
East African sleeping sickness:
- More severe, rapid progression (recurrent fevers–> neurological disease–> coma–> death)
Transmission: Tsetse fly (painful bite)
Diagnosis: blood smear
Tx:
Blood borne= Suramin
CNS= Melarsoprol
Plasmodium vivax/ovale
Malaria: fever, H/A, anemia, splenomegaly
- 48 hr cycle (fever on 1st, 3rd day)
- Dormant form in liver
Transmission: Mosquito
Diagnosis: Blood smear
- Trophozoite ring
- RBC schizont with merozoites
Tx:
- Chloroquine (blocks heme ploymerase)
- Mefloquine for resistant strains
- Life-threatening: IV quinidine (test for G6PD)
- **Add primaquine (test for G6PD) to kill hypnozoites in liver
Plasmodium falciparum
Malaria: fever, H/A, anemia, splenomegaly
- Severe, irregular fever
- Parasitized RBCs occlude brain capillaries–> cerebral malaria, kidneys, lungs
Transmission: Mosquito
Diagnosis: Blood smear
- Trophozoite ring
- RBC schizont with merozoites
Tx:
- Chloroquine (blocks heme ploymerase)
- Mefloquine for resistant strains
- Life-threatening: IV quinidine (test for G6PD)
Plasmodium malariae
Malaria: fever, H/A, anemia, splenomegaly
- 72 hour cycle of fever
Transmission: Mosquito
Diagnosis: Blood smear
- Trophozoite ring
- RBC schizont with merozoites
Tx:
- Chloroquine (blocks heme ploymerase)
- Mefloquine for resistant strains
- Life-threatening: IV quinidine (test for G6PD)
Babesia
Babesiosis: fever, hemolytic anemia
- Seen in NE USA
- Increased risk of severe disease in asplenia
Transmission: Ixodes tick
Diagnosis: blood smear (ring form, “Maltese cross), PCR
Tx: Atovaquone + azithromycin
Trypanosoma cruzi
Chagas’ disease: dilated cardiomyopathy, megacolon, megaesophagus
Transmission: Reduviid bug (“kissing bug”)- painless bite–> feces enter wound
Diagnosis: Blood smear
Tx: Nifurtimox
Leishmania donovani
Visceral leishmaniasis: spiking fevers, hepatosplenomegaly, pancytopenia
Transmission: sandfly
Diagnosis: macrophages with amastigotes
Tx: sodium stibogluconate
Trichomonas Vaginalis
Vaginitis: foul-smelling, greenish discharge
- Itching, burning
Transmission: sexual (must have host- no cyst form)
Diagnosis: Trophozoites (motile) on wet mount
- Strawberry cervix
Tx: Metronidazole (patient and partner) (GET on the Metro: G= giardia, E= entamoeba, T= Trichomonas)
Enterobius Vermicularis
Pinworm
Intestinal infection–> anal pruritis (“Scotch tape test”)
Transmission: food contaminated with eggs
Tx: Bendazoles, pyrantel pamoate (“Bendy” worms)
Ascaris Lumbricoides
Giant roundworm
Intestinal infection
Transmission: Fecal-oral; see eggs under microscope
Tx: Bendazoles, pyrantel pamoate
Strongyloides stercoralis
Intestinal infection: N/V, diarrhea, anemia
Transmission: larvae in soil penetrate skin
Tx: Albendazole, ivermectin
Ancylostoma duodenale, Necator Americanus
Old world, new world hookworm
Intestinal infection–> anemia (suck blood) (microcytic anemia)
Transmission: larvae penetrate skin
Treatment: Bendazoles, pyrantel pamoate
Dranunculus medinensis
Skin inflammation, ulceration
Transmission: drinking water
Tx: slow extraction of worm
Onchocerca volvulus
“River blindness”: microfilariae migrate to eye–> die–> inflammatory response–> opacity
- Hanging groin
- Lymphadenopathy
- Allergic reactions
Transmission: Female black fly
Tx: Ivermectin (Iver for River blindness)
Loa Loa
Swelling in skin, pain and edema in eye (worm in conjunctiva)
Transmission: female deer fly (horse, mango fly)
Treatment: Diethycarbamazine
Wucheria bancrofti
Blocks lymphatic drainage–> elephantiasis (~1 year after bite)
Transmission: female mosquitoes (night)
Tx: Diethylcarbamazine
Toxocara canis
Visceral larval migrans: granulomas in viscera (including CNS)–> death from respiratory failure, cardiac arrhythmias, brain damage
Transmission: food contaminated with eggs (carried by cats, dogs)
Tx: Albendazole, mebendazole
Taenia Solium
Cestode (tapeworm)
1. Ingestion of larvae in undercooked pork–> Intestinal infection
Tx: Praziquantel
- Ingestion of eggs (fecal-oral)–> Cysticercosis, neurocysticercosis
Tx: Praziquantel, bendazoles for neurocysticercosis
Diphyllobothrium latum
Cestode (tapeworm)
Vitamin B12 deficiency (tapeworm competes for B12 in intestine)–> anemia
Transmission: Ingestion of larvae from raw freshwater fish
Treatment: Praziquantel
Echinococcus granulosus
Cestode (tapeworm)
Ingestion of eggs (dog feces)
Cysts in liver (anaphylyaxis if released–> pretreat with ethanol injection before removing)
Tx: Bendazoles
Schistosoma
Trematode
- Liver and spleen granulomas, fibrosis, inflammation
- S. haematobium–> SCC of bladder
- S. Mansoni–> portal HTN
Transmission: Snails= host–> cercariae penetrate skin
Tx: praziquantel
Clonorchis sinensis
Trematode= Chinese liver fluke
- Biliary tract inflammation–> pigmented gallstones
- Associated with cholangiocarcinoma
Transmission: undercooked fish
Tx: Praziquantel
Paragonimus Westermani
Trematode
- Lung inflammation; secondary bacterial infection–> hemoptysis
Transmission: undercooked crab meat
Tx: Praziquantel
Live, attenuated vaccines
Smallpox Yellow fever Chicken pox (VZV) Sabin's polio virus MMR (only one can be given to HIV+ patients without immune deficiency) Influenza (flumist nasal spray)
Killed vaccines
Rabies
Influenza
Salk Polio
HAV
Recombinant vaccine
HBV: antigen= recombinant HBsAg
HPV: 6, 11, 16, 18
RNA viral genomes
- All are ssRNA except Reoviridae
- All replicate in cytoplasm except Retrovirus (diploid ssRNA), influenza
+ ssRNA:
I went to a RETRO(virus) TOGA(virus) party, where I drank FLAVored(flavivirus) CORONA(virus) and ate Hippy(hepevirus) CALIfornia (calcivirus) PICkles (picornavirus)
DNA viruses
All dsDNA, linear, icosahedral, replicate in nucleus:
Hepadna (circular, incomplete) Herpes Adeno Pox (complex, has DNA-dependent RNA polymerase--> replicates in cytoplasm) Parvo (ssDNA) Papilloma (circular, supercoiled) Polyoma (circular, supercoiled)
Herpesviruses
Enveloped
dsDNA, linear
HSV1= oral, Spontaneous temporal lobe encephalitis, keratoconjunctivitis HSV2= genital HSV3= VZV= chickenpox HSV4= EBV= mono, Burkitt's, Hodgkin's, nasopharyngeal carcinoma HSV5= CMV= AIDS retinitis, congenital defects (latent in mononuclear cells= "owl's eyes") HSV6= roseola HHV7= roseola (less common) HHV8= Kaposi's sarcoma
Diagnosis:
- PCR (#1)
- Tzanck test= smear of opened vesicle (used for HSV1, 2, VZV)
- See intranuclear Cowdry A inclusions - Monospot (EBV): heterophile antibodies on agglutination of sheep/horse RBCs
- Atypical lymphocytes= reactive cytotoxic T cells
Hepadnavirus
Enveloped
dsDNA, partial circular
Hep B:
- Acute or chronic (incubation= months)
- Vaccine= recombinant (HBsAg)
- Contains reverse transcriptase (NOT retrovirus)= DNA-dependent DNA polymerase
- Uses host RNA polymerase–> viral proteins
Transmission: Parenteral, sexual, maternal-fetal
Serology:
- HBsAg= infected (acute/chronic)
- Anti-HBs= immunity (vaccine/recovered)
- HBcAg= antigen to core (infected)
- Anti-HBc= positive during infection (IgM= acute/recent, IgG= prior/chronic)
- HBeAg= Active (acute/chronic)
- Anti-HBe= Window, chronic (low infectivity, recovery)
- Risk of HCC
- ALT > AST (vs alcoholics: AST > ALT
Adenovirus
Non-enveloped
dsDNA, linear
Pharyngitis, hemorrhagic cystitis
Pneumonia
Conjunctivitis
Parvovirus
Non-enveloped
ssDNA, linear negative (smallest DNA virus)
B19= “slapped cheeks” (erythema infectiosum), 5th disease
- In SC pts–> aplastic crisis
- In uteros–> hydrops fetalis
- Adults: RBC aplasia, RA symptoms
Papillomavirus
Non-enveloped
dsDNA, circular
HPV:
1, 2, 6, 11= warts
16, 18= CIN, cervical cancer
** Recombinant vaccine
Diagnosis:
- Koilocytes on Papanicolaou smear (pap smear)
Polyomavirus
Non-enveloped
dsDNA, circular
- JC virus= PML in HIV
- BK virus= transplant patients, kidney targeted (Bad Kidney)
Poxvirus
Enveloped
dsDNA, linear (largest DNA virus)
Smallpox= germ warfare
Vaccinia= cowpox
Molluscum contagiosum= flesh-dome lesion with central dimple
Reovirus
Nonenveloped
dsRNA, linear
Icosahedral
Coltavirus= colorado tick fever (arbovirus)
Rotavirus:
- villus destruction, atrophy–> decreased Na absorption, loss of K+
Picornavirus
Non-enveloped
ssRNA+, linear
Icosahedral
PERCH:
Poliovirus
Echovirus (aseptic meningitis)
Rhinovirus (common cold)
Coxsackievirus (aseptic meningitis, herpangina, hand foot mouth disease, myocarditis)
HAV (acute Hep A virus): asymptomatic, acute, alone (no carriers)
** All but Rhino (acid-labile) are fecal-oral enteroviruses
Hepevirus
Non-enveloped
ssRNA+, linear
Icosahedral
Hep E
- Transmission= fecal-oral (waterborne epidemics)
- No carrier state, short incubation, no HCC
- Enteric, Expectant mothers (bad), Epidemic
Calcivirus
Non-enveloped
ssRNA+, linear
Icosahedral
Norovirus
Flavivirus
Enveloped
ssRNA+, linear
Icosahedral
Hep C:
- Transmission= blood, IVDU, post-transfusion
- Long incubation
- HCC risk
- Chronic, Cirrhosis, Carcinoma, Carrier
Yellow fever (arbovirus): fever, black vomit, jaundice
Dengue (arbovirus)
St. Louis Encephalitis (arbovirus)
West Nile (arbovirus)
Togavirus
Enveloped
ssRNA+, linear
Icosahedral
Rubella (German measles)
- Postauricular lymphadenopathy, arthralgias, truncal rash (head–> trunk)
- Mild in children, serious congenital disease
Eastern Equine Encephalitis (arbovirus)
Western Equine Encephalitis (Arbovirus)
Retrovirus
Enveloped
ssRNA+, linear
Icosahedral (HTLV–> T-cell leukemia)
Complex conical (HIV–> AIDS)
** contain reverse transcriptase
HIV:
- envelope proteins acquired by budding from host plasma membrane= ENV
- Env glycosylation–> gp160–> cleaved in ER/golgi–> gp120, gp41
1. gp120= docking glycoprotein*; - attach to host CD4+ cell (early= CCR5, late= CXCR4)
- attach to CCR5/CD4 on host macrophages
- CCR5 mutation–> immunity (homo), slow course (hetero)
2. gp41= transmembrane protein*; fusion and entry
3. p17= matrix protein
4. p24= capsid protein: GAG
5. reverse transcriptase: POL
Diagnosis:
- ELISA= rule out (high false-positive)
- Western Blot= rule in (high false-negative)
- PCR for viral load
- CD4+ count (< 200= AIDS) or CD4/CD8 < 1.5
Coronaviruses
Enveloped
ssRNA+, linear
Helical
Corona= common cold, SARS
Orthomyxoviruses
Enveloped
ssRNA- , linear, 8 segmented
Helical
Influenza:
- Hemagglutin= viral entry
- Neuraminidase= progeny virion release
- Genetic shift/antigenic shift= pandemics (high frequency recombination) ex: swine and human virus recombine
- Genetic drift= epidemics (minor, random mutation)
Paramyxovirus
Enveloped
ssRNA-, nonsegmented
Helical
Parainfluenza (croup)
RSV (bronchiolitis in babies, Rx= Ribavirin)
Measles:
- Cough–> conjunctivitis-> spots–> Maculopapular rash: head to toe
- Koplik spots (buccal mucosa)
- Delayed encephalitis (SSPE)
- Giant cell pneumonia (immune suppressed)
Mumps: (makes your parotids and testes as big as POM poms)
- Parotitis
- Orchitits
- Meningitis
- surface F (fusion) protein= respiratory epithelial cells fuse–> multinucleated cells
- Use Palivizumab (MAB against F) to prevent RSV in premies)
Rhabdovirus
Enveloped
ssRNA-, linear
Helical
RABIES!:
- Bullet-shaped
- Negri bodies= cytoplasmic inclusions in neurons (Purkinje of Cerebellum)
- Post-exposure prophylaxis= Wound cleansing + Rabies Ig
- Bite–> nerve axons–> CNS–> salivary glands
Filovirus
Enveloped
ssRNA-, linear
Helical
Ebola/Marburg hemorrhagic fever
Arenaviruses
Enveloped
ssRNA-, circular segments
Helical
Lymphocytic Choriomeningitis Virus (LCMV)
Lassa Fever encephalitis (mouse-borne)
Bunyaviruses
Enveloped
ssRNA-, circular segmets
Helical
California encephalitis (Arbovirus)
Sandfly/Rift valley fever (Arbovirus)
Crimean-Congo hemorrhagic fever (Arbovirus)
Hantavirus–> hemorrhagic fever, pneumonia
Delta virus
Enveloped
ssRNA-, cricular
Hep D:
Defective (needs HBV for coinfection)
- Transmission: parenteral, sexual, maternal-fetal
- Short superinfection, long coinfection
Negative stranded viruses
Must transcribe negative strand to positive: Always Bring Polymerase Or Fail Replication - Arenavirus - Bunyavirus - Paramyxovirus - Orthomyxovirus - Filovirus - Rhabdovirus
Segmented viruses
RNA viruses: BOAR
- Bunyaviruses
- Orthomyxoviruses
- Arenaviruses
- Reoviruses
Systemic symptoms of HIV infection
Histoplasma capsulatum (pulm symptoms only in immune competent): low grade fever, hepatosplenomegaly, tongue ulcer
- CD4 < 100
- Oval yeast cells in macrophages
Dermatologic symptoms of HIV infection
C. albicans (thrush): cottage-cheese lesions
- oral: CD4 < 400
- esophageal: CD4< 100
- Pseudohyphae
Bartonella henselae: superficial vascular proliferation
- Neutrophilic inflammation
GI symptoms of HIV
Cryptosporidium: chronic watery diarrhea
- CD4 < 200
- Acid-fast cysts in stool
Neurologic symptoms of HIV
JC virus: encephalopathy
- CD4 < 200
Toxoplasma: abscesses
- CD4 < 100
Cryptococcus neoformans: Meningitis
- CD4 < 50
CMV: Retinitis
- CD4 < 50
Dementia due to HIV
Oncologic processes in HIV
HHV8: Kaposi’s sarcoma
- Lymphocytic inflammation
EBV:
- hairy leukoplakia (tongue);
- non-Hodgkin’s lymphoma (large cell)- seen on Waldeyer’s ring
- CNS lymphoma (focal or multiple)
HPV: Squamous cell carcinoma (anus, cervix)
Respiratory processes in HIV
CMV: Interstitial pneumonia
- Owl’s eye intranuclear inclusions
Aspergillus: invasive
- pleuritic pain, hemoptysis, infiltrate on imaging
Pneumocystis jirovecii: Pneumonia
- CD4 < 200
Mycobacterium aviium intracellulare: TB-like
- CD4 < 50
- Prophylax with azithromycin
CD4 < 200
- Pneumocystis jirovecii: Pneumonia
- JC virus: encephalopathy
- Cryptosporidium: chronic watery diarrhea
CD4 < 100
- C. albicans (esophageal thrush): cottage-cheese lesions
- Toxoplasma: abscesses
- Histoplasma capsulatum (pulm symptoms only in immune competent): low grade fever, hepatosplenomegaly, tongue ulcer
CD4 < 50
- CMV: Retinitis
2. Cryptococcus neoformans: Meningitis
Prion diseases
PrPc= normal cellular prion protein
PrPsc= Beta-pleated form; transmissible
- Accumulation–> spongiform encephalopathy (dementia, ataxia, death)
Creutzfeld-Jacob= sporadic, rapidly progressive dementia
Gerstmann-Straussler-Scheinker= inherited
Acquired= Kuru, New Variant CJD
Normal flora in body
Skin= staph epidermidis
Nose= staph epidermidis, colonized by s. aureus
Oropharynx= viridans group strep
Dental plaque= strep mutans
Colon= Bacteroides fragilis > e. coli
Vagina= lactobacillus; colonized by e. coli and group B strep
Bugs causing food poisoning
Vibrio parahaemolyticus, vulnificus= contaminated seafood (wounds for vulnificus)
Bacillus cereus= reheated rice
S. aureus= meats, mayonnaise, custard; preformed toxin
Clostridium perfringens= reheated meat
C. botulinum= improperly canned food
E. coli= undercooked meat (O157:H7)
Salmonella= poultry, meat, eggs
Bloody diarrhea
Campylobacter Salmonella Shigella EHEC EIEC Yersinia enterocolitica Entamoeba histolytica
Watery diarrhea
ETEC (Stable and Labile toxins) Vibrio C. Diff (can also have blood) C. perferingens Protozoa (giardia, crypto) Noro, Rotavirus
Common causes of pneumonia neonates
Group B strep
E. coli
Common causes of pneumonia: children
RSV/ viruses Mycoplasma Chlamydia trachomatis C. pneumoniae Streptococcus pneumonia
“Runts May Cough Chunky Sputum”
Common causes of pneumonia: adults 18-40
Mycoplasma
C. pneumoniae
S. pneumoniae
Common causes of pneumonia: adults 40-65
S. pneumoniae H. influenzae Anaerobes Viruses Mycoplasma
Common causes of pneumonia: elderly
S. pneumoniae Influenza Anaerobes H. influenzae Gram-negative rods
Common causes of meningitis: newborns
Group B strep
E. coli
Listeria
Common causes of meningitis: children (6 months-6 years)
Strep pneumo
N. meningitidis
H. flu type B
Enteroviruses
Common causes of meningitis in 6-60 year olds
S. pneumo
N. meningitidis
Enteroviruses
HSV
Common causes of meningitis in 60+ years
S. pneumo
Gram-negative rods
listeria
Meningitis: CSF findings
Bacterial= normal pressure, PMNs, increased protein, decreased sugar
Fungal/TB= normal pressure, Lymphocytes, increased protein, decreased sugar
Viral= normal pressure, lymphocytes, normal/elevated protein, normal sugar
UTI findings
Predisposition:
- Women (10x more common)
- Males= congenital defects in infants, vesicoureteral reflux
- Elderly males= enlarged prostate
Diagnostics:
- Bacterial UTI= positive leukocyte esterase
- Gram-negative UTI= positive nitrite test
Causes:
- E. coli
- Staph saprophyticus
- Klebsiella pneumoniae (urease positive)
- Serratia marascens= nosocomial, drug resistant
- Enterobacter cloacae= nosocomial, drug resistant
- Proteus mirabilis= motile, “swarm” in agar; urease positive–> struvite stones
- Pseudomonas= nosocomial, drug resistant
ToRCHeS
Toxoplasma:
- triad: chorioretinitis, hydrocephalus, intracranial calcifications
Rubella:
- triad: Septal defects/PDA/pulmonary artery hypoplasia or stenosis, cataracts, deafness (+/- “blueberry” rash)
CMV:
- Hearing loss, seizures, petechial rash, “blueberry” rash
HIV:
- Recurrent infections, chronic diarrhea
Herpes Simplex Virus 2:
- Encephalitis, herpetic lesions
Syphillis:
- Stillbirth, hydrops fetalis, facial abnormalities (Hutchinson’s teeth, saddle nose, short maxilla), saber shins, deafness (CNVIII)
