Microbiology Flashcards
What is virulence?
the capacity of a microbe to cause damage to the host
What is a virulence factor?
Specific component of a pathogen that causes disease
e.g. adhesin, impeding, aggressin
What are the virulence factors that are linked to S. aureus wound infections?
Adhesins
enable binding of organism to host tissue.
Expresses FIBRINOGEN BINDING and COLLAGEN BINDING adhesins i.e. they attach to open wounds where these things are exposed
What are the virulence factors that are linked to necrotising fasciitis?
Panton-Valentine Leukocidin: specific toxicity for leukocytes and destroys extracellular matric
PRECEDING INFLUENZA SYNDROME, Rapid progression, acute respiratory distress, hypoxaemia, multiorgan failure despite antibiotic therapy, necrotizing haemorrhagic pneumonia
What are the virulence factors that are linked to (staph A) toxic shock?
SUPERANTIGEN Toxinose TSST-1: results in massive release of cytokines and inappropriate immune response. Shock, rash, desquamation
Rapid progression (48hrs), high fever, vomiting, diarrhea, sore throat, muscle pain
What are the virulence factors associated with S. pyogenes (group a strep) colonization?
Capsule: contains hyaluronic acid, high levels of capsule production leads to increased colonization
Adhesins: fibronegen binding
What are the virulence factors associated with S. pyogenes classification?
Lancefield Group M (Adhesins: fibronegen binding )
Refers to carbohydrates on wall that bind to stuff
Aggressins: GROUP A STREPTOCOCCUS OR GAS Beta hemolytic virulence factor: complete hemolysis (
Cause tissue damage and ulcers)
and DNAses
What are the virulence factors associated with S. pyogenes evasion of the host immunce system?
Capsule: helps reduce phagocytosis
What are skin diseases associated with GAS?
Impetigo, cellulitis, erysipelas & necrotising fasciitis
Key factors to evolution of bacteria?
Mobile genetic elements: this means that DNA can move throughout the genome and therefore create or reverse mutations.
Pathogenecity Islands: genomic islands that can be transferred from bacterium through horizontal gene transfer
Bacteriophage: virus that invades bacteria
Antibiotic of choice for Staph Aureus?
Flucloxacillin
Treatment options for methicillin resistant staphylococcus aureus?
Doxycycine
Co-trimoxazole
Clindamycin
Vancomycin
Treatment for necrotising fascilitis?
LIFE THREATENING
Requires immediate surgical debridement + antibiotics depending on organisms isolated from tissue taken on operating
Treatment for Streptococcus pyogenes?
Penicillin (will also be treated by flucloxacillin)
- is mostly commonly seen in females age 20-50 especially with a history of -, -, polyarthritis or gammopathy,
Likely sites are -, - or - site
Pyoderma gangrenoosum
UC, Crohns
legs, trunk, stoma
Staph Aureus infections can happen via? (SHHIICS)
Skin sepsis (infected cuts, wounds etc.)
Hospital staff 30% of carry St. aureus
Hair follicle or sebum gland (boil/ carbuncle)
Infected eczema
Impetigo
Cellulitis
Staphylococcal scalded skin syndrome – tampons left in for long time
Staphylo- - is a skin commensal, not usually pathogenic
May cause infection in association with - - and -
- (produces “slime” that allows it to stick to - material)
coccus epidermidis
artificial material (joints,valves)
Intravenous catheteres
prosthetic
Group A streptococci are associated with which type of infections?
Throat (streptococci pneumoniae) and skin
What is necrotisisin fasciitis and which group of organisms cause Type II?
Strep Group A
Bacterial infection spreading along FASCIAL planes
Severe pain
Urgent surgical debridement
Leg ulcers should always be swabbed t/f
F
only if signs of cellulitis and infection present
Tinea means?
ringworm
Tinea corporis - body
Tinea barbae - bear etc
What is the pathogenesis of RINGWORM
Fungus enters abraded or soggy skin (HOT SWEATY CONDITIONS)
Infects KERATINISED tissue
Increased epidermal turnover causes scaling
Inflammatory response
LESION GROWS OUTWARD AND HEALS IN CENTRE GIVING RING APPEARANCE
Ringworm - women more commonly affected in groin and foot t/f
f
men
foot ring worm mainly affects children t/f
f
scalp
How to treat SMALL AREAS infected skin/nails w ringworm?
Clomitrazole (canestan) cream
How to treat scalp infections ringworm?
Terbinafine orally
Itraconazole orally
Terbinafine cream
Candida commonly seen under the breasts in females, groin areas, abdominal skin folds etc, nappy area in babies
t/f
t
Treatment candida?
Clotrimazole cream - antiyeast
Oral Fluconazole
Scabies is not highly infections t/f
F
HIGHLY INFECTIOUS
Treatment for scabies is Malathion lotion applied body overnight and washed off
t/f
T
Treatment for lice infections?
malathion lotion
Pediculus capitis is a type of fungus t/f
F
lice
Which patients need single room isolation due to infection control?
Group A strep
MRSA
Scabies
WHat is the organism that most commonly causes necrotizing fasciitis?
GAS, can be caused by staph A too
Presentation of parovirus B19?
Lacy macular rash on body
“slapped cheek disease”
Complications of parovirus include acute - , espiecally in the - is seen as the rash fades. The most common group to experience this is -
arthritis, wrists, adults
Complications of parovirus B19 include? SAC
Spontanous Abortion
Aplastic issues - sudden drop in haemoglobin, sickle cell anaemia etc.
Chronic anaemia (in immunosupressed patients)
Lab confirmation of parovirus is done via skin swabs t/f
F antibody test (IgM)
Orf presents as:
It is common in:
Transmitted by:
Firm fleshy nodules on the hands of farmers
Transmission via SHEEP AND GOATS
Orf MUST have a lab confirmation via swab t/f
f
clinical diagnosis
Orf is treated via encanflovir t/f
f
self limiting
Chancre is a symptom of -, it is a sign of - infection. It is when there are - ulcers on the -
syphilis, primary, painless, genitals
Red rash over body, prominent on soles of feet and palms of hand is characteristic of what?
SECONDARY PHASE of syphilis infection
Mucuous membrane “snail track” ulcers are characteristic of what?
SECONDARY PHASE of syphilis infection
Syphilis is caused by sexual transmitted infection with bacterium Treponema pallidum
t/f
t
How is diagnosis of syphilis made?
blood test or swab of chancre for PCR
How is syphilis treated?
injections of penicillin
What are the three types of third phase syphilis infection?
Cardiovascular- can cause aortitis, result aneurysm
Gummatous - benign, causes tumor-like balls of inflammation
Neurosyphilis - can cause meningitis and other neuro issues
Lyme disease is caused by viral infectiont/f
F
bacteria BORRELIA BURGDORFERI
Lyme disease is transmitted by?
ticks!!!
What is the early and late presentation of lyme disease?
Early: erythema migrans, this is a migrating red rash
Late: heart block, nerve palsies (dysfunction of a cranial nerve), arthritis
Any presentation of lyme disease is confirmed via swab of erythema migrans t/f
f
blood test antibody to organism
mainly LATE presentation
Transmission of zika virus is?
Sexual transmission or mosquitos
Symptom onset: 3–12 - after exposure
Symptoms resolution: 2–7 - after onset
Which virus?
days, days, zika
Symptoms of zika virus?
Mild fever Rash (mostly maculopapular) Headaches Arthralgia Myalgia Non-purulent conjunctivitis
Varcella zoster evolution is - to - to - to - to recovery. it also presents with - and -.
macules, papules, vesicles, scabs
fever, itch
Herpes zoster virus common in?
Elderly and immunocompromised
Herpes zoster is characterised by?
Dermatomal distribution
Tingling/pain to erythema to vesicles to crusts
What is an opthalmic zoster?
herpes zoster in opthalic division of trigeminal nerve. Urgent opthalmic referral needed
What is Ramsay-Hunt syndrome?
herpes zoster reactivation in geniculate ganglion (7th and 8th cranial nerves.) Can cause facial palsy, deafness, vertigo and tinnitus
Live attenuated vaccine is available for chickenpox and is routinely used in the UK for children t/f
F
live vaccine used in suseptible health c workers rather than kids
Vaccination for shingles routinely in 70 year olds
t
reduce incidence 38%
What is the therapy for VZV and HSV
ACICLOVIR
- does not eliminate latent virus
How can you confirm presence of HSV and VSV?
Swab with viral transport medium -preferred for viral skin / mucous membrane infections
Antibody tests
yellow top vacutainer
where virus infected site is inaccessible or as adjunct to swab
What is herpangina?
Blistering rash of back of mouth
Caused by enterovirus
Herpangina is selflimitng t/f
t
hand, foot and mouth disease is caused by?
enteroviruses
Lab diagnosis for enteroviruses?
swab lesion or sample of stool for PCR
There are 2 types of HSV. Type 1 is the - cause of oral lesions, while type 2 - casuses this, they both cause half of - cases and both types cause -.
main, rarely
genital
encephalitis
Herpes simplex virus presents in - with extensive - around the mouth, primary - and lasts about a -.
pre-school children
ulceration
gingiviostomatitis
week
Herpes simplex virus can spread to …
eczema and cause eczema herpeticum
Recurrent herpes simplex virus is characterised by?
blistering rash at vermillion border (border of lips)
Warts are caused by?
Human papilloma viurs
HPV can cause?
genital warts
cervical cancer
Molluscum contagiosum presents as? Treatment? Common in?
Fleshy, firm, umbilicated, pearlescent nodules
1 to 2 mm diameter
Self limiting but take months to disappear, liquid nitrogen or salicylic acid in children
Common in children
Erythema multiforme can be a consequence of triggering latent HSV. What can trigger it?
drug reaction and some infections
presents as target lesions with erythema
Pityriasis versicolor is treated by?
antifungal - KET CON A ZOLE
