Eye Infections 1

Question 1

Noncontagious inflammation of the lower portion of the eyelids and eyelashes

Answer 1

Blepharitis

Question 2

Causes blepharitis

Answer 2

Poor eyelid hygiene
Excess oil produced by the glands in the eyelids

Bacterial infection: Staphylococcus aureus
Allergic reaction

Question 3

Decryocystitis

Answer 3

Inflammation of the lacrimal sac

Partial or complete obstruction within the sac or nasolacrimal duct. Bacteria are trapped initiating acute or chronic infection
Older patients are predisposed d/t lacrimal drainage system loses elasticity & tears fail to flush debris

Question 4

Conjunctivitis

Answer 4

Inflammation of the conjunctiva (Outermost layer of the eye covering the sclera)

Could extend to the eyelids
Cornea (keratitis)
Or sclera (episcleritis)
Progressive keratitis can lead to ulceration, scarring, and blindness

Question 5

Bacterial conjunctivitis

Answer 5

Adults: Staphylococcus aureus

Both: (Streptococcus pneumoniae, Haemophilus influenzae)

infants: Neisseria gonorrhoeae

Question 6

viral conjunctivitis

Answer 6

Viral usually associated with an upper respiratory infection

Cold, sore throat

Question 7

Sx viral/ bacterial and allergic conjunctivitis

Answer 7

Bacterial 
Stringy discharge
Swelling of the conjunctiva
Redness, tearing
Irritation (gritty feeling)
Can spread to other eye

Viral 
Watery discharge
Red eye
Irritation
Can spread to other eye

Allergic: both eyes, itching, swollen eyelids

Question 8

Microorganisms that cause ophthalmia neonatorum

Answer 8

Microorganisms that typically cause this type of conjunctivitis are the sexually transmitted microorganisms which cause gonorrhea and chylamidia
Neisseria gonorrhoeae, Chlamydia trachomatis, Herpes simplex virus

Question 9

Ophthalmia neonatorum

Answer 9

Ophthalmia neonatorum
Severe conjunctivitis of newborns
Can acquire the infection at birth

Microorganisms that typically cause this type of conjunctivitis are the sexually transmitted microorganisms which cause gonorrhea and chylamidia
Neisseria gonorrhoeae, Chlamydia trachomatis, Herpes simplex virus

Question 10

Endophthalmitis

causative agents

Answer 10

Caused commonly by normal flora of the eyelids
Staphylococcus epidermidis
Caused less commonly by gram-neg microorganisms
Pseudomonas sp.
Prognosis poor

Question 11

Endophthalmitis

Answer 11

Rare, intraocular infection
Infection of the aqueous or vitreous humor
Usually caused by bacteria or fungi
Occurs most commonly after cataract surgery

Question 12

Etiological agent of Post-surgical endophthalmitis:

Answer 12

Pseudomonas

Question 13

uveitis

description and types

Answer 13

Inflammation or swelling of the eye structures responsible for the eye’s blood supply
Iris, ciliary body, choroid
Three types of uveitis
Iritis (or anterior uveitis)
Intermediate uveitis (cyclitis)
Posterior uveitis

Question 14

Iriitis and periorbital cellulitis

Answer 14

Redness, pain, photophobia due to painful movement of inflamed iris
Blurred vision in severe inflammation

Periorbital cellulitis
Acute infection of the tissues surrounding the eye
Can lead to orbital cellulitis and protrusion of the eyeball
Complications include meningitis

Question 15

Orbital Cellulitis common agents (bacterial)

Answer 15

Bacterial
Staphylococcus aureus, Staphylococcus epidermidis
Streptococcus pneumoniae, Streptococcus pyogenes
Haemophilus influenzae
Moraxella catarrhalis
Eikenella corrodens, Pasteurella multocida
Associated with dog bites
Mycobacterium tuberculosis
MOTT

Question 16

Orbital Cellulitis agents (fungal and parasites)

Answer 16

Common agents
Fungal
Rhizopus sp.
Aspergillus sp.
Penicillium sp.
Candida paropsilosis

Parasitic
Trichinella spiralis
Echinococcus granulosus
Fly larvae (maggots)

Question 17

Haemophilus influenza

Answer 17

Gram-negative, bacillus (rod)
Non-motile, non-spore forming
Fastidious, facultative anaerobe
Haemophilus – “blood loving”
Requires 2 erthrocyte factors for growth
X – hemin
V – nicotinamide adenine dinucleotide
Both of these factors are released from lysed RBCs
Therefore H. influenzae is grown on chocolate agar
Lysed erthrocyte medium

Resident of the nasopharyngeal mucosa
Sometimes in the conjunctivae, genital tract

Question 18

H. Influenza Path. mech.

Answer 18

Attachment to respiratory epithelial cells is accomplished using pili
It is suggested that there is a coordinated response between attachment and capsular development
Endotoxin in the cell wall is toxic to ciliated respiratory cells

Question 19

Nonencapsulated (or non-typeable) strains of H. influenza cause

Answer 19

Otitis media, conjunctivitis, bronchitis, pneumoniae

Question 20

Dz caused by the most virulent H. influenza (capsulated)

Answer 20

6 serotypes (a-f) based on biochemically different capsules
Haemophilus influenzae type b (HiB)
Most virulent strain
Responsible for such infections as bacteremia, meningitis, cellulitis, septic arthritis, pneumoniae

Question 21

H. influenza spread

Answer 21

Eustachian tubes to cause otitis media
Sinuses – sinusitis
Respiratory tract to cause bronchitis and pneumoniae.

Patients with COPD and cystic fibrosis
Non-typeable H. influenzae can colonize the lower respiratory tract and exacerbate these conditions

Question 22

Srep. pneumoniae

Answer 22

Gram-positive, cocci
Usually seen in pairs (diplo), but occur singly and in chains
Non-spore formers, non-motile
Fastidious, grows in 5% carbon dioxide
Facultative anaerobe
Under optimal conditions, S. pneumoniae’s generation time is 20-30 minutes

Question 23

Srep. pneumoniae growth

Answer 23

Growth on blood agar medium results in alpha-hemolysis
Green zone in the agar medium surrounding the colonies
Represents partial hemolysis of red blood cells

Question 24

Strep. pneumoniae virulence

Answer 24

Capsule
Determinant of virulence
Interferes with phagocytosis
Blocks C3b opsonization
Antipneumococcal vaccines are designed based on pneumococcal capsular antigens

Question 25

The reaction to identify S. pneumoniae

Answer 25

Quellung reaction Serotyping used to identify a particular capsule type 90 capsular types identified Forms the basis of antigenic serotyping Antibody which reacts with a particular capsule type will cause capsular swelling

Question 26

Staphylococcus aureus id

Answer 26

Gram-positive cocci, clusters Virulence factors Cytolytic toxins- affect red blood cells and leukocytes Alpha-hemolysin- destroys platelets and causes severe tissue damage Beta-hemolysin- acts on the sphingomyelin of red blood cell membranes Staphylococcal leucocidin: Panton-Valentine leukocidin exotoxin lethal to polymorphonuclear leukocytes. Implicated in contributing to the invasiveness of S.aureus and suppressing phagocytosis`

Question 27

Staphylococcus aureus virulence factors (enzymes)

Answer 27

Coagulase - a critical virulence marker Hyaluronidase: hydrolyzes hyaluronic acid which makes up connective tissues. Allows for easy spread of infection Lipases :Act on fats and oil secreted by sebaceous glands. Allows for colonization of the microorganisms

Question 28

Protein A

Answer 28

Virulence factor of S. aureus A cellular component in the cell wall of S. aureus Able to bind the Fc portion of the antibody, thus avoiding phagocytosis

Question 29

Staphylococcus epidermidis id

Answer 29

Gram-positive cocci Coagulase-negative (Staphylococcus aureus is coagulase-positive) Indigenous to mammals Normal skin flora Most prevalent and persistent species on human skin and mucosal surfaces Comprise 60-95% of all staphylococcal species

Question 30

S. epidermidis Abx resistance

Answer 30

Antibiotic-resistance is plasmid-mediated -via conjugation Certain aminoglycoside-resistance genes have been transferred from S. epidermidis to other S. epidermidis and S. aureus species Penicillin, macrolides, tetracycline, chloramphenicol, trimethoprim, aminoglycosides. With few exceptions, almost all S. epidermidis infections are hospital-acquired

Question 31

Chlamydia trachomatis

Answer 31

Obligate intracellular parasites Deficient in independent energy metabolism Most common STD in the world. Cause of blindness and infertility. Trachoma: Due to infection by Chlamydia trachomatis Transmitted through infected secretions: eye discharge eye-seeking flies. Inflammatory reactions results in scarring on the conjunctiva Forces the eyelid to turn inward where the eyelashes can rub the cornea

Question 32

Chlamydia trachomatis life cycle

Answer 32

Life cycle Alternates between a non-replicating, infectious elementary body and a replicating, noninfectious reticulate body. Elementary body – dispersal form Induces its own endocytosis with host cell Once inside, it germinates into a vegetative, reticulate form Reticulate body divides every 2-3 hrs Incubation in host cell, 7-21 days Reverts back to elementary bodies Released from cell by exocytosis

Question 33

Chlamydia trachomatis

Answer 33

Immunofluorescence | Cell wall structurally similar to gram-neg; gram stain does not work well with this microorganism

Question 34

MOTT

Answer 34

``` MOTT – (mycobacteria other than tubercle bacilli) NTB (nontuberculous mycobacteria) These infections are associated with Trauma Contact lens wear Wound contamination with soil and water Most common causes are Mycobacterium chelonae Mycobacterium fortuitum ```

Question 35

MOTT (mycobacteria other than tubercle bacilli)

Answer 35

NTB (nontuberculous mycobacteria) These infections are associated with: trauma, contact lens wear, wound contamination with soil and water Most common causes are: Mycobacterium chelonae Mycobacterium fortuitum

Question 36

etiological agent of | Keratitis and Corneal ulcers

Answer 36

M. fortuitum

Question 37

Eikenella corrodens

Answer 37

Microaerophilic, gram-negative rods. Normal flora of human, mucosal surfaces Culture requires CO2 environment and hemin in the medium. Identification of this bacterium could be missed. For proper laboratory identification, lab must be notified if the wound is: head or neck result of human bites Usually a part of a mixed infection, particularly with Streptococcus sp.

Question 38

Eikenella corrodens | is frequently associated with

Answer 38

chronic infections and abscess formation: orbital infections. Not typically associated with eye infections However, rare cases have occurred related to bite wounds. Congenital lacrimal duct obstruction Probing procedure resulted in an infection Isolate identified as Eikenella corrodens

Question 39

Gets its name from the fact that it forms pits on the surface of agar medium on which it is grown Gives it a corroded appearance

Answer 39

Eikenella corrodens

Question 40

Francisella tularensis Path Dx Chrc

Answer 40

Chrc: gram - coccobaccilus, oxidase -, urease -, non motile Path: tularemia (highly infectious- 10-50 organisms can infect) Dx: growth on chocolate agar

Question 41

Tularemia | Sx and Path

Answer 41

Path: Francisella is primary a pathogen of squirrels and rabbits. Humans infected by: bite of tick or deer fly, eating undercooked meat, handling infected rabbit carcasses Sx: skin ulcers, swollen/painful lymph nodes, INFLAMED eyes, sore throat and mouth sores

Question 42

Cat scratch dz | agent andpt Hx

Answer 42

``` Bartonella henselae (gram - bacillus) Hx of exp to cats or being scratched ```

Question 43

Ocular Sx of cat scratch dz

Answer 43

Bartonella henselae Parinaud's oculoglandular syndrome ( conjunctivitis and neuroretinitis) vitritis, pst uveitis White retinal or choroidal lesions

Question 44

Moraxella catarrhalis | Characteristics

Answer 44

gram - diplococci + oxidase Abx resistance: Penicilin, ampicillin, amoxicilin

Question 45

Moraxella catarrhalis path dx Assoc infx

Answer 45

path: assoc with periorbital cellulitis, resp ( imp cause of bronchopulmonary inx), mid. ear, CNS, eye, joints Dx: hocky puck test Assoc infx: periorbital cellulitis

Question 46

HSV assc eye infections

Answer 46

Viral blepharitis (vesicles on lid margins and around the eye; later breaks open and forms lesions which can be come super infected by skin flora). Occular herpes Scleritis infections of lacrimal apparatus endophthalmitis

Question 47

Occular herpes

Answer 47

Caused by HSV(linsear, ds DNA, outer env) HSV infx of conjunctiva swelling of eylids Herpes simplex Keratitis ( if cornea involved)--> destruction, ulceration and perforation of cornea [ denritic keratitis whn virus branches out in a dendritic pattern].

Question 48

Agents responsible for viral blepharitis, scleritis, infection of lacrimal apparatus, and endophthalmitis

Answer 48

HSV (in addition causes ocular herpes)- dsDNA w/ out env Varicella zoster. viral blepharitis: when then face is involved during chicken pox, then blisters form on the lid margins. wart like lesions (molluscom contagiosum) can form from the pox virus.

Question 49

Phalangeal conjunctival fever and epidemic keratoconjunctivitis are caused by:

Answer 49

adenovirus ( linear, dsDNA, icosah, non-env) | It also cause: tonsillitis, common cold, ear infx, conjunctivitis).