Microbiology Flashcards by K M

What are virulence factors?

Factors that contribute to a microbes ability to cause a pathology

How well did you know this?

Not at all

Perfectly

What is virulence?

How effective an organism is at causing a pathology

How well did you know this?

Not at all

Perfectly

Give examples of virulence factors

Adhesin
Impedin
Aggressin

How well did you know this?

Not at all

Perfectly

What does adhesin do?

Enables binding of the organism to host tissue (Adhesive=Adhesin)

How well did you know this?

Not at all

Perfectly

What does impedin do?

Enables the organism to avoid host defence mechanisms

How well did you know this?

Not at all

Perfectly

What does aggressin do?

Causes damage to the host directly

How well did you know this?

Not at all

Perfectly

T/F most of the natural flora of the skin are gram -ve

False

They are mostly gram +ve

How well did you know this?

Not at all

Perfectly

Where can gram -ve bacteria be found on the skin?

Underarm

Groin

How well did you know this?

Not at all

Perfectly

What can staph aureus cause?

Superficial lesions
Systemic illness
Toxinoses

How well did you know this?

Not at all

Perfectly

What are 2 types of toxinoses?

Toxic shock syndrome

Scalded skin syndrome

How well did you know this?

Not at all

Perfectly

Is coagulase a virulence factor?

Yes

How well did you know this?

Not at all

Perfectly

What does coagulase allow the organism to do?

Coagulate plasma

How well did you know this?

Not at all

Perfectly

Are all virulence factors on an organism expressed at the same time?

How well did you know this?

Not at all

Perfectly

What is TSST-1?

Toxic shock syndrome

How well did you know this?

Not at all

Perfectly

What are the symptoms of TSST-1?

High fever
Vomiting
Diarrhoea
Sore throat
Muscle pain

How well did you know this?

Not at all

Perfectly

What causes TSST-1?

Overstimulation of the immune system

How well did you know this?

Not at all

Perfectly

How do toxins get in the blood stream in TSST-1?

Diffuse through the vaginal wall into the blood stream

How well did you know this?

Not at all

Perfectly

What are the diagnostic criteria for TSST-1?

Fever
Diffuse macular rash and desquamation
Hypotension
>3 organ systems involved

How well did you know this?

Not at all

Perfectly

What do super antigens cause/

Massive release of cytokines and inappropriate immune response

How well did you know this?

Not at all

Perfectly

What is PVL?

Panton-valentine-Leukocidin

How well did you know this?

Not at all

Perfectly

What does PVL do?

Destroys leukocytes

How well did you know this?

Not at all

Perfectly

Who has increased levels of PVL?

Patients with skin disease

How well did you know this?

Not at all

Perfectly

List 3 defense mechanisms of intact skin:

Sebum and fatty acids inhibit bacterial growth
Competitive bacterial flora
Dry desiccation of micro-organisms

How well did you know this?

Not at all

Perfectly

How is a diagnosis of a skin lesion made?

Swab of lesion if the surface is broken
Pus or tissue if deeper lesion
+/- blood cultures

How well did you know this?

Not at all

Perfectly

Is Staphylococcus gram +ve or -ve?

+ve

Is staphylococcus aerobic or anaerobic?

Aerobic but faculatively anaerobic

Is Staph aureus coagulase +ve or -ve?

+ve

What can staph aureus cause?

Boils and carbuncles Minor skin sepsis Infected eczema Impetigo

How can staph aureus infections be treated?

Flucloxacillin

What is the treatment for MRSA?

Doxycycline Co-trimoxazole Clinamycin Vancomycin

What are some toxins that strains of staph aureus can produce?

Enterotoxin TSST PVL

Where is coagulase negative staph found?

Epidermis

What is a strain of coag -ve staphylococci that causes UTIs in women?

Saprophyticus

Is streptococcus gram +ve or -ve?

+ve

How are streptococci classified?

Haemolysis on blood agar

Which strep is Alpha haemolytic?

Strep pneumonia | Strep viridans

Which strep is Beta haemolytic?

Group A step -Step pyogenase Group B - Neonatal meningitis

What can strep pyogenase cause?

``` Infected eczema Impetigo Cellulits Erysipelas Necrotising fasciitis ```

What is Necrotising fasciitis?

Bacterial infection spreading along fascial planes below skin surface leading to rapid tissue destruction

What causes type 1 NF?

Mixed anaerobes and coliforms

What causes type 2 NF?

Group A strep infection

What is the treatment for NF?

Immediate surgery

What strep causes gamma haemolysis?

Enterococci

What is the pathogenesis of a fungal infection?

Fungus enters abraded or soggy skin Hyphae spread in stratum corneum Infects keratinised tissues only Increased epidermal turnover causing scaling Inflammatory response provoked Hair follicles and shafts invaded Lesions grow outwards and heal in centre giving ring appearance

What is the name for fungal infections in: - Ringworm - Scalp - Beard - Body - Hand - Nails - Groin - Foot

``` Tinea = ringworm Tinea capitis = scalp Tinea barbae = beard Tinea corporis = body Tinea manuum = hand Tinea ungium = nails Tinea cruris = groin Tinea pedis = foot ```

Which gender is more commonly affected by Fungal infections?

Men

Who does scalp ringworm mainly affect?

Children

How are fungal infection aquired?

Other infected humans Animals Soil

How are fungal infections diagnosed?

Clinical appearance Woods light Skin scrapings, nail clippings and hair

What is the treatment of fungal infections?

``` Small areas: -Clotrimazole cream -Topical nail paint Scalp infections -Oral terbinafine -Itraconazole orally ```

Where do candida infections usually occur?

Skin folds where area is warm and moist Under breast in females Groin areas Nappy areas

How are candida infections diagnosed?

Swab for culture

How are candida infections treated?

Clotrimazole cream | Oral Fluconazole

What organism causes scabies?

Sarcoptes scabiei

What is the incubation period for scabies?

Up to 6 weeks

What are the symptoms of scabies?

Intensely itchy rash affecting finger webs, wrists and genital area

What is the treatment of scabies?

Overnight malathion lotion | Benzyl benzoate

What is the name for Lice in the: - Head - Body - Pubic area?

Head - Pediculus capitis Body - Pediculus corporis (Vagabond's disease) Pubic - Phthirus pubis

What is the treatment for lice?

Malathion

What causes chickenpox and shingles?

Varicella zoster virus

What part of varicella zoster is chickenpox?

Varicella

Who gets chickenpox?

Children

What are the signs and symptoms of chicken pox?

Generalised rash, itch and fever | Macules to papules to vesicles to scabs to recovery

What are the complications of chickenpox?

``` Secondary bacterial infection Pneumonitis Haemorrhagic Scarring Encephalitis ```

How does neonatal VSV occur?

Secondary to chickenpox in mother in late pregnancy

Which part of VSV is shingles?

Herpes zoster

How does shingles occur?

Reactivation of VSV

Who gets shingles?

Elderly | Immunocompromised

What is the distribution of shingles?

Dermatomal distribution

What is ramsay-hunt syndrome?

Vesicles and pain in auditory canal and throat Facial palsy of the 7th nerve Irritation of Vestibulocochlear nerve causing deafness, vertigo and tinnitus

How many types of Herpes simplex virys are there?

What does HSV 1 cause?

Main cause of oral lesions | Causes half of genital lesions

What does HSV type 2 cause?

Rare cause of oral lesions | Causes half of genital lesions

How is HSV treated?

Aciclovir

How is HSV confirmed?

Swab with viral transport medium | Antibody tests

What is eythema multiforme?

Target lesions with erythema

What can tirgger erythema multiforme?

Drug reactions | HSV infections

What does molluscum contagiosum look like?

Fleshy, firm, umbilicated, pearlescent nodules | 1 to 2 mm in diameter