Day 3 (3): Ocular Microbiology Flashcards

Question

Describe Staphylococcus spp.

Answer 1

Mnemonic: CLUSTER of people posing for a group photo with a CAT wearing GOLD (aureus) medals Gram POSITIVE cocci - purple/blue In grape-like CLUSTERS Facultative anaerobe: aerobe with faculty to become anaerobe CATalase POSITIVE: (+) bubble formation - Common infectious agent in EXTERNAL eye infections (especially BLEPHARITIS) Treatment: Penicillins, Cephalosporins, Clindamycin, Tobramycin, Erythromycin, Vancomycin, Fluoroquinolones (Levo, Gati, Moxi)

Answer 2

Gram POSITIVE cocci - purple/blue Grape-like CLUSTERS Facultative anaerobe Catalase POSITIVE: (+) bubble formation Coagulase POSITIVE: (+) clumping or clots BETA-hemolytic: (+) GOLD pigments Virulence factors: 1. Coagulase: activates prothrombin and causes fibrin to clot - fibrin formation around the bacteria protective from phagocytosis 2. Hemolysin: destroys RBCs, WBCs, platelets - tested with blood agar 3. Leukocidin: destroys WBC - Panton-Valentine-Leukocidin: in CA-MRSA, (+) recurrent abscess 4. Penicillinase: destroys B-lactam ring on penicillins 5. Exfoliatin: causes skin to slough off (Scalded Skin Syndrome) 6. Toxic Shock Syndrome Toxin (TSST-1): cytokine storm 7. Enterotoxin: gastroenteritis 8. Staphylokinase: thrombolytic to break up blood clots and spread from the initial site of infection

Answer 3

Gram POSITIVE cocci - purple/blue Grape-like CLUSTERS Facultative anaerobe Catalase POSITIVE: (+) bubble formation Coagulase NEGATIVE: (-) clumping GAMMA-hemolytic Novobiocin SENSITIVE: (+) zone of inhibition - Part of normal skin flora - Problematic in immunocompromised and nosocomial - (+) Biofilm formation in catheters and prosthetic devices - Multiple antibiotic resistance

Answer 4

Gram POSITIVE cocci - purple/blue Grape-like CLUSTERS Facultative anaerobe Catalase POSITIVE: (+) bubble formation Coagulase NEGATIVE: (-) clumping GAMMA-hemolytic Novobiocin RESISTANT: (-) zone of inhibition - UTI in females

Answer 5

Mnemonic: STRIPtococcus Gram POSITIVE cocci - purple/blue In PAIRS/CHAINS/STRIPS Facultative anaerobe: aerobe with faculty to become anaerobe CATalase NEGATIVE: (-) bubble formation Classification based on: 1. Hemolytic activity in blood agar Beta = CLEAR zone = complete hemolysis = pyogenes, agalactiae Alpha = GREEN zone = partial hemolysis = viridans, pneumoniae Gamma = NO zone = non-hemolytic 2. Lancefield antigen: antigenicity of C carbohydrate on cell wall Group A: Pyogenes Group B: Agalactiae No antigen: Viridans and Pneumoniae - Common cause of CONJUNCTIVITIS and KERATITIS Treatment: Penicillins, Cephalosporins, Clindamycin, Erythromycin, Vancomycin, Fluoroquinolones (Levo, Gati, Moxi)

Answer 6

Lancefield antigen: Group A Gram POSITIVE cocci - purple/blue In CHAINS/STRIPS Facultative anaerobe/Microaerophile CATalase NEGATIVE: (-) bubble formation BETA-hemolytic Bacitracin SENSITIVE: (+) zone of inhibition Virulence factors: 1. Pyogenes = Pus-producing = microaerophile = skin infections 2. Streptolysin O: similar to hemolysin of S. aureus - destroys RBCs, WBCs, and platelets - test: Anti-Streptolysin O antibodies 3. Erythrogenic Toxin: similar to TSST-1 of S. aureus - cytokine storm 4. Streptokinase: thrombolytic to break up blood clots and spread from the initial site of infection 5. M protein: adherence, antigenicity and anti-phagocytic

Answer 7

Thrombolytic: Staphylokinase :: Streptokinase Cytokine Storm: Toxic Shock Syndrome Toxin - 1 :: Erythrogenic Toxin Hemolysis: Hemolysin :: Streptolysin O

Answer 8

Lancefield antigen: Group B Gram POSITIVE cocci - purple/blue In CHAINS/STRIPS Facultative anaerobe CATalase NEGATIVE: (-) bubble formation BETA-hemolytic Bacitracin RESISTANT: (-) zone of inhibition Mnemonic: B for baby (found in vagina)

Answer 9

Lancefield antigen: NONE Gram POSITIVE - purple/blue In PAIRS (diplococci), LANCET-shaped with tapered ends and surrounding CLEAR area Facultative anaerobe CATalase NEGATIVE: (-) bubble formation ALPHA-hemolytic Optochin SENSITIVE: (+) zone of inhibition (+) Quellung Reaction: swelling when mixed with antibodies and methylene blue Mnemonic: P for parents (pneumonia and meningitis in adults) - vaccinate with Pneumococcal vaccines (PCV13 and PPSV23)

Answer 10

Lancefield antigen: NONE Gram POSITIVE cocci - purple/blue In CHAINS/STRIPS Facultative anaerobe CATalase NEGATIVE: (-) bubble formation ALPHA-hemolytic Optochin RESISTANT: (-) zone of inhibition Mnemonic: V as in verde/green = alpha-hemolytic Found in GI tract, gums, teeth, tongue, saliva - dental infections, endocarditis

Answer 11

Gram POSITIVE bacilli - purple/blue Single cell, in clumps or in short chains (BOXCAR formation) SQUARED ends Obligate aerobes Ubiquitous SAPROPHYTES SPORE-forming Medium: (+) cotton or cloud-like with fringe-like edges FULMINANT keratitis and endophthalmitis (POST-TRAUMA) Food poisoning and gastroenteritis Virulence Factors: inactivated by high temperature 1. Enterotoxins (Heat-labile and Heat-stable) - diarrhea 2. Emetic toxins - nausea and vomiting Treatment: Resistant to beta-lactam antibiotics Clindamycin, Erythromycin, Vancomycin, Fluoroquinolones (Levo, Gati, Moxi) * Antibiotic tx will not alter course of s/sx because they're caused by PREFORMED exotoxins.

Answer 12

Klebs-Loeffler Bacillus Gram POSITIVE bacilli/rods - purple/blue CLUB-shaped, or CHINESE CHARACTERS shape Facultative anaerobe NON-spore forming DIPHTHERIA - colonizes pharynx, (+) pseudomembrane formation --> exotoxin release - attacks cardiac and neural tissues --> myocarditis and neuropathy - avoid scraping pseudomembrane or exudates in throat --> increases release of toxin - MEMBRANOUS conjunctivitis or ULCERATIVE keratitis Virulence Factor: Necrotizing Exotoxin - "anti-human antibody" like an anti-ribosomal antibiotic - blocks human protein synthesis DX: 1. Potassium Tellurite Agar: brown colonies with black haloes 2. Loeffler's Medium: club-shaped bacillus - (+) Babes-Ernst/Volutin Granules: intracytoplasmic deposits of polymetaphosphate that appear red when stained with methylene blue TX: 1. Antitoxin: only inactivates CIRCULATING exotoxin 2. Penicillins/Erythromycin/Vancomycin: kill the bacteria 3. TDaP: since infection does NOT always result to immunity

Answer 13

Gram POSITIVE bacilli - purple/blue PLEOMORPHIC Aerotolerant Primary cause of acne Primary cause of CHRONIC BLEPHARITIS and DELAYED-ONSET ENDOPHTHALMITIS (esp. post-intraocular or cataract surgery) Normal part of flora feeding on fatty acids and sebum in follicles Treatment: Penicillins, Cephalosporins, Clindamycin, Erythromycin, Vancomycin, Fluoroquinolones (Levo, Gati, Moxi)

Answer 14

Actinomyces israelli Gram POSITIVE - purple/blue Obligate ANaerobe Branching/FILAMENTOUS Part of the normal flora of the mouth and GIT Disease: 1. Abscess formation following trauma to mouth 2. Dental infections 3. Canaliculitis 4. Chronic conjunctivitis DX: Tissue/Discharge CS on Blood Agar with Vitamin K - ANAEROBIC incubator - (+) sulfur granules: microcolonies of Actinomyces TX: Penicillin, TMP-SMX +/- incision and drainage Nocardia asteroides Gram POSITIVE - purple/blue Partially ACID-FAST: (+) mycolic acid on cell wall Obligate aerobe Branching/FILAMENTOUS NOT part of the normal flora OPPORTUNISTIC: mistaken for TB Disease: 1. Canaliculitis 2. Chronic conjunctivitis 3. Abscess formation 4. Pneumonia DX: Modified Acid-Fast Stain - decolorize with sulfuric acid instead of acid alcohol - culture: (+) earthy odor TX: Penicillin, TMP-SMX +/- incision and drainage Mnemonics: SNAP S - sulfamethoxazole/sulfur granules N - nocardia A - actinomyces P - penicillin

Answer 15

Gram NEGATIVE cocci - red/pink Only pathogenic G (-) cocci KIDNEY-BEAN shape DIPLOCOCCI and facing each other DONUT-formation Facultative anaerobe Found INTRACELLULARLY (inside PMNs) CAPNOphilic (HIGH carbon dioxide concentration) Medium: Thayer-Martin VPN (chocolate agar + antibiotics) - Vancomycin: inhibit G (+) bacteria - Polymyxin/Colistin: inhibit G (-) bacteria - Nystatin: inhibit fungi - Trimethoprim: inhibit Proteus Diseases: 1. Meningococcemia/Meningitis 2. Gonorrhea 3. Hyperacute, purulent conjunctivitis 4. Ophthalmia Neonatorum Conjunctivitis 5. Marginal Keratitis

Answer 16

Gram NEGATIVE cocci - red/pink KIDNEY-BEAN shape DIPLOCOCCI and facing each other DONUT-formation Facultative anaerobe Found INTRACELLULARLY (inside PMNs) Lives in nasopharynx of humans only CAPNOphilic (HIGH carbon dioxide concentration) Medium: Thayer-Martin VPN Maltose- and Glucose-fermenter (MeninGitis) Diseases: 1. Meningitis: most common cause in 6 mos - 2 yo 2. Meningococcemia Virulence factors: 1. Pili and capsule: adherence and anti-phagocytic 2. Endotoxin: destroys blood vessels = (+) petechiae 3. IgA Protease DX: Blood/CSF GS/CS or petechial biopsy TX: Penicillin G, Ceftriaxone

Answer 17

Gram NEGATIVE cocci - red/pink KIDNEY-BEAN shape DIPLOCOCCI and facing each other DONUT-formation Facultative anaerobe Found INTRACELLULARLY (inside PMNs) Medium: Thayer-Martin VPN + HIGH CO2 CAPNOphilic (HIGH carbon dioxide concentration) Commonly occurs with CHLAMYDIA Glucose-fermenter ONLY (Gonorrhea) Diseases: 1. Gonorrhea: 2nd most common STI - urethritis, rectal gonorrhea, pelvic inflammatory disease 2. Ophthalmia Neonatorum Conjunctivitis - transmitted to infant during vaginal delivery - manifest at the 1st or 2nd day of life - may cause blindness - Prophylaxis: Erythromycin Drops - Treatment: Ceftriaxone injection and Erythromycin syrup Virulence factor: 1. Pili: adherence 2. Endotoxin DX: Discharge GS/CS from urethra TX: 1. Ceftriaxone IM: N. gonorrhoeae 2. Azithromycin PO: C. trachomatis

Answer 18

Gram NEGATIVE coccobacilli (short rods) - red/pink DIPLOBACILLI in BOXCAR formation Virulence factors: 1. Endotoxin 2. Proteases: canthal maceration Moraxella lacunata: ANGULAR BLEPHAROCONJUNCTIVITIS - Chronic, mild blepharoconjunctivitis localized on outer canthus Treatment: Neomycin, Gentamycin, Tobramycin, Fluoroquinolones (Levo, Moxi, Gati) - Erythema of the edges of the lids - Canthal maceration especially the outer canthus - Superficial infiltration of the cornea (ULCERATIVE KERATITIS) - Grayish yellow discharge, (+) matting, mainly at the angles

Answer 19

Gram NEGATIVE coccobacilli - red/pink Short, slender rods Facultative anaerobe CAPNOphilic (HIGH carbon dioxide concentration) BLOOD-loving: needs blood containing medium OPPORTUNISTIC: attacks lungs after viral influenza OBLIGATE human parasite (+) Quellung Reaction; similar to S. pneumoniae (+) SATELLITISM: - most strains of Haemophilus don't grow on blood agar (contains X factor but no V factor) - S. aureus produces the V factor as a metabolic by-product when growing in a culture media containing blood. - Haemophilus may grow on blood agar very close to the colonies of Staphylococcus aureus 6 mos - 2 yo: no antibodies to capsule because maternal Ab gone Forms: 1. Encapsulated (Type B) = bad = invasive/systemic 2. Non-encapsulated/Non-typeable = non-invasive, local infection Virulence factors: 1. Capsule: antiphagocytic 2. Hemolysin 3. Lipopolysaccharide Lipid A Endotoxin: heightened local inflammatory response Diseases (non-encapsulated form): 1. Acute mucopurulent conjunctivitis 2. Dacryocystitis 3. Endophthalmitis DX: Chocolate Agar with INCREASED CO2 at 37 degrees Celsius - heating the blood agar releases: 1. Hemin (X factor) 2. NAD+ (V factor) TX: 1. Steroids: 15-20 mins prior to antibiotics to limit local inflammatory response 2. Cephalosporins (2nd/3rd), Aminoglycosides, Fluoroquinolones 3. HiB Vaccine: children takes 3-5 years to produce own Ab to capsule

Answer 20

Tests if organism used oxygen for energy production

Answer 21

Gram NEGATIVE bacillus Obligate aerobes Ubiquitous OPPORTUNISTIC: nosocomial or immunocompromised) Oxidase POSITIVE Lactose NEGATIVE: will NOT tolerate anaerobic respiration Glucose NEGATIVE Motile: (+) flagella Virulence factors: 1. Hemolysin: beta-hemolytic 2. Exotoxin A: similar to diphtheria toxin which inhibits protein synthesis 3. Endotoxin: stromal ring infiltrate Diseases: 1. Ulcerative Keratitis/Corneal melt - especially in SOFT CONTACT LENS wearers 2. Scleritis/Scleral melt: due to exotoxin A 3. Dacryocystitis 4. Endophthalmitis DX: CS in Blood Agar - green metallic colonies with fruity GRAPE ODOR - (+) Pyocyanin --> blue; (+) Pyoverdin --> green TX: Fluoroquinolones (moxi, gati, levo), 3rd Gen. Cephalosporins (anti-pseudomonal), Polymyxin B, Aminoglycosides (tobra, ami, genta), Polymyxin E/Colistin, Carbenicillin (penicillin for Gram negative)

Answer 22

Enterobacteriaceae (E.coli, Enterobacter, Proteus, Klebsiella) Gram NEGATIVE coccobacilli to filamentous - pink/red Opportunistic and ubiquitous Facultative anaerobe Oxidase NEGATIVE Lactose POSITIVE Glucose POSITIVE Virulence factors: 1. Endotoxins/Lipopolysaccharide 2. Enterotoxins Diseases: 1. Ulcerative keratitis 2. Endophthalmitis 3. Gastroenteritis DX: MacConkey or EMB Agar (+) Swarming: Proteus (+) Mucoid/Moist colonies: Klebsiella TX: Aminoglycosides, Fluoroquinolones, Cephalosporins (3rd Gen)

Answer 23

Gram NEGATIVE - red/pink CORKSCREW-shaped, tightly coiled Moves by spinning TOO SMALL to be seen in light microscopy CANNOT be cultured in ordinary media DX: 1. Darkfield microscopy 2. Immunofluorescence tests 3. Silver stains 4. Serologic tests Famous members: 1. Leptospira: Leptospirosis 2. Borrelia burgdorferi: Lyme disease 3. Treponema pallidum: Syphilis

Answer 24

Gram NEGATIVE - red/pink Fine, helical, SPIROCHETE Microaerophile NO toxins or virulence factors (+) Jarisch-Herxheimer Phenomenon: acute worsening of s/sx after antibiotic initiation due to release of pyrogen by dead spirochetes Syphilis - sexually transmitted illness found in humans ONLY - transmission: contact with ulceration - manifestations due to host's immune response - spectrum: 1. Primary Syphilis: PAINLESS ulcer 2. Secondary Syphilis: erythematous macular rash in palms, soles and mouth; condyloma latum; ANY organ can be affected 3. Latent Syphilis: ASYMPTOMATIC 4. Tertiary Syphilis: COMPLICATIONS (gummas of skin and bones; aneurysms; neurosyphilis: meningitis, stroke, tabes dorsalis, generalized paresis) Ocular manifestations: 1. Loss of eyebrows - Secondary Syphilis 2. Conjunctivitis 3. Interstitial Keratitis 4. Episcleritis 5. Uveitis 6. Retinitis 7. Argyl-Robertson Pupil/Prostitute's Pupil - "accommodates but does not react" - midbrain lesion causing light-near dissociation 8. Optic Neuritis DX: 1. Darkfield microscopy - helical organisms moving in corkscrew fashion - only seen in lesions of PRIMARY and SECONDARY syphilis 2. VDRL/RPR: nonspecific 3. FTA-ABS/MHA-TP: specific and confirmatory 4. PCR Test TX: 1. Penicillin G 2. Doxycycline 3. Erythromycin

Answer 25

Giemsa's solution: methylene blue + eosin + Azure B Steps: 1. FIXATION with METHANOL (30 seconds) 2. IMMERSION in 5% GIEMSA STAIN (20–30 minutes) or 10% (5–10 minutes) for emergencies 3. FLUSHING with tap water 4. AIR DRYING

Answer 26

Gram NEGATIVE but NO peptidoglycan layer OBLIGATE INTRACELLULAR: uses host's ATP as energy source CANNOT be cultured on artificial media: only LIVING CELLS Contains BOTH RNA and DNA Prefers COLUMNAR epithelial cells lining mucous membranes MOST COMMON sexually transmitted illness Serotypes: 1. A to C: Trachoma 2. D to K: Inclusion Conjunctivitis 3. L: Lymphogranuloma Venereum Life Cycle: 1. Elementary Body: metabolically inert infectious particle that attaches and enters columnar cells 2. Initial/Reticulate Body: after inhibition of phagosome-lysosome fusion 3. Inclusion Body: or liberated as more EB Diseases: 1. Trachoma/Follicular Conjunctivitis/Adult Inclusion Conjunctivitis - Serotypes A, B, C - Chronic conjunctivitis that's the LEADING CAUSE OF PREVENTABLE BLINDNESS - Insidious course: over 10-15 years - Inflammation + scarring --> cicatricial ENtropion --> corneal scarring - (+) Artl's Line: thick band of scar tissue running horizontally in the junction of the anterior 1/3 and posterior 2/3 of palpebral conjunctiva - (+) Herbert's Pits: depressions in the upper margin of cornea which are remnants of large conjunctival follicles - TX: Azithromycin PO (topicals INEFFECTIVE) 2. Neonatal Inclusion Conjunctivitis/Ophthalmia Neonatorum - Serotypes D to K - Purulent yellow discharge and lid edema - Acquired by neonate during vaginal delivery - DX: Scraping of palpebral conjunctival surface - TX: Doxycycline/Tetracycline (adults), Erythromycin/Azithromycin - Systemic treatment needed for eye infections because infants can develop pneumonia after conjunctivitis - Prophylaxis: Erythromycin drops 3. Keratitis (punctate or marginal) 4. Reiter Syndrome: triad of CONJUNCTIVITIS + URETHRITIS + ARTHRITIS 5. Lymphogranuloma venereum: painless genital ulcer progressing to tender inguinal or femoral lymphadenopathy DX: 1. Giemsa Stain: (+) BASOPHILIC INTRACYTOPLASMIC BODIES - Collection of IB/RB in conjunctival cells - Stains glycogen 2. PCR Test 3. Immunofluorescence Assay 4. Culture in live cell lines: not possible in artificial media

Answer 27

1. Primary stain: CARBOLFUCHSIN (red) 2. HEATING: for dye penetration 3. Decolorizer: ACID ALCOHOL - cell wall lipids of mycobacteria do not dissolve thus remaining red - "hold FAST to the RED stain" 4. Counterstain: METHYLENE BLUE - stains cell walls/membranes of non-mycobacteria Remember: Mycobacteria - lipid-rich walls that stain red/pink = ACID FAST

Answer 28

ACID FAST bacilli - red/pink against a background of blue Rod-shaped Obligate aerobe Slow-growing Cell wall is 40% lipid (mycolic acid) Hydrophobic = clumped colonies or floating blobs FACULTATIVE INTRACELLULAR growth inside MACROPHAGES - caseous necrosis --> MULTINUCLEATED GIANT CELLS Ocular Manifestations: 1. Phlyctenulosis - nodular inflammation of the cornea or conjunctiva that results from a hypersensitivity reaction to a foreign antigen - (+) phlyctenules: subepithelial inflammatory nodules containing histiocytes, lymphocytes, plasma cells, and neutrophils 2. Granulomatous conjunctivitis 3. Interstitial/Ulcerative keratitis 4. Endo/Panophthalmitis 5. Orbital cellulitis 6. Osteomyelitis 7. Dacryocystitis/adenitis 8. Epi/scleritis 9. Granulomatous uveitis (iris, CB, choroid) 10. Retinal granuloma DX: 1. AFB Smear/Ziehl-Neelsen Stain 2. Lowenstein-Jensen Culture 3. PPD Skin Test: delayed-type (Type 4) hypersensitivity - tests for exposure and past infection = LATENT TB 4. Interferon Gamma Release Assay 5. CXR: for PTB 6. Gene Xpert MTB/RIF: nucleic acid amplification test TX: HRZE +/- S (duration dependent on location of infection)

Answer 29

ACID FAST bacilli - red/pink against a background of blue Pleomorphic rod-shaped Obligate aerobe Cell wall is 40% lipid (mycolic acid) OBLIGATE INTRACELLULAR Grouped together like BUNDLES of CIGARS or PALISADING Grows in cooler parts of the body close to skin surface: skin, nerves, eyes, nose, testes Hansen's Disease spectrum 1. Lepromatous: most severe with NO cell mediated response - entire body covered with lumps - (+) Leonine facies: thickened facial skin - (+) Saddle Nose Deformity: destroyed nasal cartilage - damage to anterior segment of eye - thickened peripheral nerves --> decreased sensation 2. Intermediate 3. Tuberculoid: least severe with SOME cell mediated response - mild and self-limiting - (+) localized, superficial, unilateral skin and nerve involvement Ocular manifestations: 1. Lid thickening 2. Lash and brow loss 3. CN 3 and 7 palsy 4. Punctate or Avascular Interstitial Keratitis 5. Iridocyclitis 6. Nodular Epi/Scleritis DX: Skin or Nerve biopsy - Grown in footpads of mice, monkeys or armadillos - Impossible to grow in artificial media TX: 1. Rifampin 2. Dapsone 3. Clofazimine

Answer 30

HHAPPPy viruses Herpesviridae: HSV, VZV, EBV, CMV Hepadnaviridae: HBV Adenoviridae: Parvoviridae: Parvovirus B19 Papovaviridae: HPV Poxviridae: Smallpox, Molluscum Most are: DOUBLE-stranded with ICOSAHEDRAL symmetry and Replicate in NUCLEUS (since DNA) 3 are ENVELOPED: Herpes, Hepadna, Pox 3 are NAKED: Parvo, Adeno, Papova ("naked for PAP") Exceptions: 1. PARVO: so simple that it's SINGLE-stranded 2. POX: DOUBLE-stranded but so complex that it's ASYMMETRIC and replicates in CYTOPLASM

Answer 31

RNA is a PROP Picornaviridae Retroviridae Orthomyxoviridae Paramyxoviridae Most are: SINGLE-stranded HELICAL symmetry ENVELOPED 2 replicate in CYTOPLASM: Picorna and Paramyxo 2 replicate in NUCLEUS: Retro and Orthomyxo Exception: Picorna: ICOSAHEDRAL symmetry and NON-enveloped

Answer 32

Herpes simplex virus Varicella zoster virus Epstein-Barr virus Cytomegalovirus Note: All herpesviridae cause MULTINUCLEATED GIANT CELLS with INTRANUCLEAR INCLUSION BODIES and can REACTIVATE during latent phase.

Answer 33

DNA virus DOUBLE-stranded ICOSAHEDRAL symmetry Replicate in NUCLEUS ENVELOPED 2 serotypes: 1: Head and Neck 2: Ocular and Genital DX: 1. Fluorescent Antibody Technique 2. Pap Smear: (+) Lipschutz bodies (eosinophilic intraNUCLEAR IB) 3. Tzanck Smear with Giemsa Stain: (+) multinucleated giant cells with intraNUCLEAR IB (cannot distinguish between herpetic lesions) 4. Culture with live cells 5. PCR Test Diseases: 1. Cold Sores: PAINFUL fluid-filled blisters that rupture - transmitted by direct contact with mucous membranes and fluid inside the blister - travels up via sensory nerve fibers --> may reactivate if IC 2. Genital Herpes: sexually-transmitted illness 3. Encephalitis Ocular Manifestation: 1. Blepharodermatitis (vesiculo-pustular and ulcerative non-dermatomal) 2. Conjunctivitis (follicular or pseudomembranous) 3. Herpetic Keratitis: MC infectious cause of corneal blindness (dendritic, epithelial, geographic, discoform stroma, metaherpetic) 4. Iridocyclitis 5. Necrotizing Herpetic Retinopathy (acute retinal necrosis, progressive outer retinal necrosis) - may also be due to VZV Treatment: 1. Trifluridine drops 2. Acyclovir/Valcyclovir/Famciclovir/Ganciclovir

Answer 34

DNA virus DOUBLE-stranded ICOSAHEDRAL symmetry Replicate in NUCLEUS ENVELOPED MORPHOLOGICALLY-similar BUT SEROLOGICALLY-distinct to HSV Highly contagious: spread via aerosol and contact with ruptured vesicles DX 1. Fluorescent Antibody Technique 2. Pap Smear: (+) Lipschutz bodies (eosinophilic intraNUCLEAR IB) 3. Tzanck Smear with Giemsa Stain: (+) multinucleated giant cells with intraNUCLEAR IB (cannot distinguish between herpetic lesions) 4. Culture with live cells 5. PCR Test Diseases: 1. Chickenpox: GENERALIZED; "dew drops on top of a rose petal" - vesicles appear in trunk and face then erupt in crops - lesions are in varied stages - infectious until ALL LESIONS SCAB OVER 2. Herpes Zoster: DERMATOMAL reactivation from dorsal ganglion 3. Cranial Nerve Palsies 4. Myositis 5. Encephalitis Ocular Manifestation: 1. Blepharodermatitis (vesiculo-pustular and ulcerative dermatomal) --> Cicatricial En/Ectropion 2. Conjunctivitis 3. Keratitis (dendriform, punctate epithelial, nummular stromal, neurotrophic) and Corneal Melt 4. Epi/Scleritis 5. Iridocyclitis and Chorioretinitis 6. Necrotizing Herpetic Retinopathy 7. Optic Neuritis Treatment: 1. Acyclovir/Valcyclovir/Famciclovir 2. Sorivudine/Brivudine 3. Zoster Immunoglobulin 4. Varicella Vaccine

Answer 35

DNA virus DOUBLE-stranded ICOSAHEDRAL symmetry Replicate in NUCLEUS ENVELOPED Diseases: 1. Infectious Mononucleosis: kissing disease - transmission: saliva 2. Burkitt's Lymphoma: infect B lymphocytes + oncogenic potential - remains latent in B lymphocytes and mucosal cells Ocular Manifestation: 1. Dacryoadenitis 2. Conjunctivitis (follicular or membranous) 3. Keratitis (epithelial, multifocal stromal) 4. Uveitis (multifocal choroiditis) 5. Optic Neuritis DX: 1. Monospot Test: blood agglutination test which tests for heterophile antibodies, which when present, will cause clumping when exposed to equine RBCs 2. Antibody (IgM, IgG) titers to EBV capsid antigen; (+) at onset 3. Antibody to EBV nuclear antigen: (-) at onset; (+) for life 4. CBC: elevated WBCs with atypical lymphocytes 5. Culture in umbilical cord blood lymphocytes TX: 1. Acyclovir 2. Corticosteroids 3. Supportive management: may spontaneously resolve

Answer 36

DNA virus DOUBLE-stranded ICOSAHEDRAL symmetry Replicate in NUCLEUS ENVELOPED Ubiquitous; subclinical infection unless IMMUNOCOMPROMISED Infected cells become swollen --> cytomegaly Diseases: 1. Asymptomatic: 80% 2. TORCH syndrome: Toxoplasmosis, Others, Rubella, CMV, HSV 3. CMV Mononucleosis: but NEGATIVE monospot test Ocular Manifestation: 1. Endotheliitis 2. Uveitis 3. Retinitis: common in AIDS pts but NOT transplant pts DX: 1. Fluorescent Antibody Technique 2. Cytology: (+) multinucleated giant cells with intraNUCLEAR IB surrounded by OWL'S EYE HALO 3. Serology: Indirect Hemagglutination Test 4. Culture with live cells (embryonic lung and fibroblasts) 5. PCR Test TX: 1. Foscarnet 2. Ganciclovir

Answer 37

DNA virus DOUBLE-stranded ICOSAHEDRAL symmetry Replicate in NUCLEUS NAKED: non-enveloped Multiple serotypes Disease: 1. URTI: rhinitis, pharyngitis, tonsillitis 2. Pharyngoconjunctival fever: fever, pharyngitis, acute follicular conjunctivitis, tender, enlarged preauricular adenopathy 3. Gastroenteritis Ocular manifestation: 1. Acute follicular/pseudomembranous conjunctivitis 2. EPIDEMIC keratoconjunctivitis DX: 1. Fluorescent Antibody Technique 2. Serology: (+) antibody titers 3. Culture with live cells: embryonic kidney cells TX: Supportive (self-limited)

Answer 38

DNA virus DOUBLE-stranded ICOSAHEDRAL symmetry Replicate in NUCLEUS NAKED: non-enveloped Prefers SQUAMOUS epithelial cells Relapses are common because HPV DNA already found in normal tissues around the papilloma Common serotypes: 6, 11: Papillomas 16, 18: Oncogenic potential (Cervical, Nasopharyngeal) Ocular Manifestation: Verruca - benign hyperproliferation of keratinized squamous epithelium - lids, conjunctiva, punctum DX: Clinical; PCR Test TX: 1. Excision 2. Cryotherapy 3. Laser Ablation

Answer 39

DNA virus DOUBLE-stranded ASYMMETRIC and BRICK-shaped ("pox in a box") Replicate in CYTOPLASM (little space in nucleus) ENVELOPED LARGEST and MOST COMPLEX virus Common in IMMUNOCOMPROMISED STI spread by skin-to-skin contact Ocular Manifestation: 1. Molluscum Contagiosum: painless, round, waxy eyelid nodule with an UMBILICATED center - benign hyperproliferation of epithelial cells 2. CHRONIC Follicular Conjunctivitis DX: Clinical 1. Smear: (+) Henderson-Patterson bodies/Molluscum bodies - large intraCYTOPLASMIC basophilic IB inside altered keratinocytes 2. Culture 3. PCR Test TX: Excision

Answer 40

Members: 1. Poliovirus: Polio 2. Coxsackievirus A and B: Hand-Foot-Mouth Disease 3. Hepatitis A virus 4. Common Cold RNA virus SINGLE-stranded ICOSAHEDRAL symmetry Replicate in CYTOPLASM NAKED: non-enveloped SMALLEST RNA virus Ocular Manifestation: Acute Hemorrhagic Conjunctivitis - red swollen eyes with subconjunctival hemorrhage DX: 1. Serology 2. Immunofluorescence Tests 3. PCR Test 4. Culture Test

Answer 41

Members: 1. Parainfluenza Virus: Croup 2. Measles virus: Measles/Rubeola 3. Mumps virus: Mumps RNA virus SINGLE-stranded HELICAL symmetry Replicate in CYTOPLASM ENVELOPED (+) Fusion Protein: multinucleated giant cells like HERPES Diseases: 1. Measles/Rubeola - Replicates in conjunctival membranes - (+) Koplik Spots: white spots in the buccal mucosa - (+) Hirschberg's Spots: Koplik spots on the caruncle and semilunar fold - Acute catarrhal conjunctivitis (red eye with flu-like symptoms) - Epithelial keratitis - Chorioretinitis - Pneumonia, Exanthem 2. Mumps - Dacryoadenitis - Nummular keratitis - Epi/Scleritis - Iridocyclitis - Parotitis, Orchitis

Answer 42

RNA virus SINGLE-stranded HELICAL symmetry Replicate in NUCLEUS ENVELOPED Influenza Virus A, B, C: Flu virus Ocular Manifestation: 1. SUBACUTE catarrhal conjunctivitis: vs. ACUTE in Measles 2. Dacryoadenitis: similar to Mumps DX: Clinical 1. Serology: hemagglutination test 2. Culture with live cells: throat washing TX: 1. Amantidine/Rimantidine 2. Zanamivir/Oseltamivir 3. Flu vaccine yearly

Answer 43

RNA virus SINGLE-stranded HELICAL symmetry Replicate in NUCLEUS ENVELOPED Diseases: Acquired Immunodeficiency Syndrome - If CD4 < 200 or with AIDS-defining condition Ocular manifestations: 1. HIV Retinopathy: cotton-wool spots with feathered edges - Microangiopathy: most common ocular manifestation of HIV 2. CMV Retinitis 3. Ocular Toxoplasmosis 4. Herpes Zoster/Simplex 5. Neurosyphilis 6. Molluscum Contagiosum 7. Kaposi Sarcoma 8. Orbital Lymphoma DX: 1. ELISA: screening 2. Western Blot Test: confirmatory 3. PCT Test for viral load: maintenance TX: Antiretrovirals

Answer 44

EUKARYOTES with no chlorophyll Obligate aerobes RIGID cell wall BILAYERED cell membrane made of ERGOSTEROL - punches holes: Amphotericin B, Nystatin - stops synthesis: Azoles, Echinocandin Exist in 3 forms: 1. Yeast: UNIcellular growth form - reproduce by BUDDING - may not separate forming long chains: PSEUDOHYPHAE 2. Mycelia: MULTIcellular colonies of clumped intertwined hyphae - Hyphae: threadlike branching tubules of fungal cells attached end to end 3. Dimorphic: either as MOLD or YEAST depending on environment and temperature - Yeast: BODY temperature (in vivo) - Mycelia: ROOM temperature (in vitro) DX: 1. Giemsa Stain 2. Gomori Methenamine Silver Stain 3. Potassium Hydroxide Mount 4. Culture: Saboraud's Agar, Blood Agar

Answer 45

Yeast 1. Candida Mycelia (filamentous) - septated 1. Aspergillus 2. Fusarium Mycelia (filamentous) - NON-septated 1. Mucor 2. Rhizopus 3. Rhizomucor Dimorphic 1. Sporothrix schenckii 2. Blastomyces dermatitidis 3. Histoplasma capsulatum 4. Coccidioides immitis

Answer 46

Both stains anything with CARBOHYDRATES: 1. Glycogen 2. Mucin: glycolipids, glycosaminoglycans, glycoproteins 3. Basement membrane: connective tissues) 4. Fungal cell walls: high levels of carbohydrates PAS Stain: 1. Periodic Acid 2. Schiff Reagent: gives purple/magenta color 3. Hematoxylin: blue counterstain 4. Appearance: red/purple fungi against blue background 5. Needs to be ALIVE GMS Stain: 1. Chromic Acid 2. Methenamine Silver: gives it black color 3. Green Dye: counterstain 4. Appearance: black fungi against green background 5. May be DEAD or ALIVE

Answer 47

Potassium Hydroxide - Strong alkali - Dissolves keratin in the tissues surrounding the fungi for better visualization Steps: 1. Scrapings placed in slide and 10-20% KOH added 2. Slide left to stand for 5-15 minutes or until clear 3. View under microscope

Answer 48

pH 5.0 due to fermentation: inhibits bacterial growth Ingredients; 1. Dextrose: fermentable nutrition 2. Peptones: provides nitrogen for growth 3. Chloramphenicol, Gentamycin, Tetracycline: inhibit bacterial growth

Answer 49

Candida albicans YEAST: UNIcellular (+) PSEUDOHYPHAE: elongated budding cells Normal flora of skin, mouth and GIT NOT NORMAL in blood Ocular manifestations: 1. Mucocutaneous Candidiasis: lids and conjunctiva 2. Ulcerative keratitis 3. Infectious Crystalline Keratopathy 4. Endophthalmitis 5. Chorioretinitis DX: 1. KOH Mount 2. Gomori-Methenamine-Silver Stain 3. Saboraud Agar: white pasty colonies with FRUITY odor 4. Blood culture: candidemia TX: 1. Azoles (keto, fluco, mico, itra) 2. Amphotericin B

Answer 50

Aspergillus MYCELIAL (multicellular) - SEPTATED Ubiquitous (damp, decaying vegetation) Members: 1. Fumigatus 2. Flavus: (+) aflatoxin in peanuts, grains and rice 3. Niger Disease: Aspergillosis +/- Aspergilloma Ocular manifestation: 1. Ulcerative Keratitis 2. Scleritis 3. Endophthalmitis 4. Dacryocystitis 5. Orbital Cellulitis DX: 1. Sputum culture 2. CBC: eosinophilia 3. Chest X-ray/CT Scan: aspergilloma 4. KOH Mount: (+) conidiophore with sterigmata and long chains of radiating conidia TX: 1. Steroids: to limit inflammatory response 2. Surgery: for aspergilloma 3. Voriconazole 4. Amphotericin B 5. Caspofungin

Answer 51

Fusarium solani MYCELIAL (multicellular) - SEPTATED Ubiquitous saprophytic Seen in people working in the fields during harvest season Ocular manifestation: 1. Keratomycosis (ulcerative keratitis): most common cause 2. Endophthalmitis 3. Disseminated if immunocompromised DX: 1. Saboraud Agar: white and violet cottony colonies with REVERSE PIGMENTATION 2. KOH Mount: SICKLE/BANANA-shaped macroconidia TX: largely resistant to most anti-fungals 1. Natamycin 2. Amphotericin B

Answer 52

Histoplasma capsulatum Blastomyces dermatitidis Coccidioides immitis: Chorioretinitis Sporothrix schenckii: Sporotrichosis/Granulomatous Blepharoconjunctivitis DIMORPHIC: - mycelia at room temperature/Saboraud (25 degrees) - yeast at body temperature/Blood Agar (37 degrees) SS: subcutaneous nodules which necrose and ulcerate Others: systemic manifestation DX: Biopsy of affected tissue 1. Gomori-Methenamine-Silver Stain 2. Saboraud/Blood Agar Culture TX: SS: Potassium iodide, Itraconazole, Fluconazole Others: Amphotericin B, Itraconazole

Answer 53

Rhizopus Rhizomucor Mucor MYCELIAL - NON-septated Saprophytic Disease: Rhinocerebral/Orbital MUCORMYCOSIS DX: (+) black nasal discharge and biopsy TX: 1. Aggressive debridement 2. Amphotericin B, Posaconazole

Answer 54

Onchocerca volvulus: Onchocerciasis/River Blindness - second-leading infectious cause of blindness after trachoma - microfilariae migrate to the eye TX: Ivermectin

Answer 55

Trichinella spiralis/Trichinellosis - larvae in raw pork is ingested and migrates to skeletal muscles DX: 1. Muscle biopsy 2. Increase muscle enzymes 3. CBC: eosinophilia TX: Albendazole

Answer 56

Toxocara canis/Toxocariasis - ingestion of ova from dog feces - larval migration to the eyes Manifestation: Ocular Toxocariasis 1. Chronic endophthalmitis 2. Posterior pole or peripheral granuloma 3. Chorioretinitis DX: 1. ELISA 2. Biopsy 3. CBC: eosinophilia TX: Albendazole

Answer 57

Loaloa/Loiasis - may localize to the conjunctiva - (+) Calabar swellings: allergic reaction to the metabolic products of the worms or to dead worms; can occur anywhere, but frequently on the forearms TX: 1. Diethylcarbamazine 2. Extraction of worm from the eye

Answer 58

Taenia solium/saginata - due to ingestion of undercooked pork/beef - travels to the CNS or eye and form calcified cysts with surrounding inflammatory reaction DX: 1. CT Scan --> biopsy 2. CBC: eosinophilia TX: 1. Praziquantel 2. Albendazole

Answer 59

Crab Louse - Six-legged ectoparasite - Adapted only to THICK hair - (+) Pruritus: hypersensitivity to saliva of louse - (+) Macula Ceruleae: bluish-brown macules from hemosiderin deposition secondary to louse bite marks Disease: Phthiriasis 1. Phthiriasis pubis: pubic hair 2. Phthiriasis palpebrarum/ciliaris: eyelashes/lid margin - Chronic Blepharoconjunctivitis - Eyelid Infestation - Follicular Conjunctivitis DX: Slit-Lamp Exam for nits and adult lice TX: 1. Mechanical removal 2. Petroleum jelly over eyelids

Answer 60

Demodex folliculorum/brevis - Normal commensal parasite of hair, eyelash follicles, sebaceous and Meibomian glands - Common in elderly - Appearance: worm-like CIGAR-shaped body with 8 stumpy legs anteriorly - Feeds on skin cells and oils in the hair follicle Manifestations: 1. Demodectic blepharitis 2. Lid hyperemia 3. Meibomitis --> Chalazion DX: Slit-Lamp Examination - (+) Sleeves :around the base of eyelashes; cuffs of hypertrophic follicular epithelium - (+) Epilated eyelashes TX: Lid Scrubs (ether, tea tree oil)

Answer 61

Acanthamoeba Ubiquitous free-living protozoa found mostly in fresh water 2 Forms: 1. Active Trophozoite 2. Dormant Cyst Diseases: 1. Immunocompetent: keratitis esp. in contact lens wearers 2. Immunocompromised: chronic granulomatous brain infection - both stages present Ocular manifestions: 1. Epithelial or Stromal Keratitis with ring infiltrates 2. Perineural infiltrates 3. Nodular Scleritis DX: Corneal scraping 1. Calcofluor White: visualize CYSTS - binds to cellulose (acanthamoeba cyst) and chitin (fungi) --> (+) fluorescence 2. Non-nutrient Agar with E. coli overlay: visualize TROPHOZOITES - selective media; alternative to corneal biopsy for keratitis - (+) trails or tracks TX: 1. Polihexanide/PHMB 0.02% 2. Chlorhexidine 3. Propamidine isethionate 0.1% (Brolene) 4. Corneal transplant: for severe corneal damage

Answer 62

Obligate INTRACELLULAR fungi Opportunistic infection in IMMUNOCOMPROMISED 2 stages: 1. Schizogenic stage 2. Sporogenic stage Transmission: 1. Fecal-oral route 2. Direct inoculation into cornea: trauma (mud) Ocular manifestations: 1. Immunocompetent: focal stromal keratitis 2. Immunocompromised: punctate epithelial keratitis - course punctate keratitis with minimal stromal inflammation 3. Mixed follicular-papillary conjunctivitis DX: Calcofluor White - (+) intraepithelial PELLET-like spores TX: 1. Bicyclohexylammonium fumagillin (Fumidil B) 2. Propamidine isethionate (Brolene)

Answer 63

Toxoplasma gondii Obligate INTRACELLULAR protozoan Hosts: Definitive: Cat Intermediate: Humans, Mice 2 forms: 1. Sporocysts (infectious) 2. Bradyzoites 3. Tachyzoites (proliferative) Transmission: 1. Inhalation: cysts in cat feces 2. Ingestion: cysts in raw pork Ocular manifestation: 1. Anterior Uveitis 2. Chorioretinitis: congenital or reactivation 3. Papillitis: specific type of optical neuritis DX: 1. Blood agglutination 2. Antibody immunofluorescence 3. ELISA TX: 1. Sulfadiazine or Pyrimethamine 2. Clindamycin: if sulfadiazine