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Infection And Immunity > Infection > Flashcards

Infection Flashcards

1
Q

Describe bacterial cells

A

Lack nuclear membrane and organelles
Cell wall
Cocci and bacilli
Binary fission

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2
Q

Describe a viral cell

A

DNA can be single/double, circular/linear, RNA/DNA
This is surrounded by a capsomere coat
Nucleocapsid surrounded by lipid bilayer of host cell origin
Enveloped more susceptible to drying, acidity, and bile

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3
Q

Describe Fungi

A

Eukaryotes
Thick chitin cell wall
Grow as filaments or single cells
Superficial or deep infections

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4
Q

Evidence for the endosymbiotic origin of mitochondria

5

A

Ribosomes are more like prokaryotic ones
Have a circular form of DNA
Control their own division
Production of energy associated with inner membrane as in prokaryotes
Antibiotics which affect bacterial ribosomes will also affect mitochondria

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5
Q

Microbial classification techniques

5

A

Macroscopic- growth patterns, size, texture, pigment
Microscopic- size, shape, arrangement of cells
Antigenic properties- determines the relatedness
Subcellular- molecular constituents for taxon/organism group
DNA base composition ratio- extent to which DNA is G/C based

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6
Q

Definition of epidemiology

A

Study of distribution and determinants of a disease within human populations. Occurence, risk, treatments, progression, diagnostic test performance.

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7
Q

Early history of infectious diseases

A

Soil, water, lifestyle
Practical anatomy experiments on gladiators
The plague- quarantine and body disposal
Leprosy- quarantine little effect

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8
Q

Ebola
Location
Description

A 
Emerged in Guinea
Filovirus
Negative sense ssRNA genome
5 species and 2 related filo viruses
Contact with infected bats and monkeys, 
Causes necrosis of liver, spleen, lymph nodes and lungs
Haemorrhagic symptoms after 7-15 days
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9
Q

Strain variation- Zairean + Reston Ebola viruses

A

90% case fatality rate in the zaire strain
0% fatality in the Reston strain
Fatal inflammatory response ‘cytokine Storm’
Can cause inflammatory sequela after clearance of the virus

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10
Q

Inactivation of virus on skin

A

Inactivated by desiccation, ph 5.5, inhibitors formed by commensal organisms

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11
Q

Human papilloma virus

A

Circular dsDNA genome, non enveloped
Infect the basal layer of differentiating epithelium
Causes warts, sometimes cancerous
Causes cervical cancer- first cancer vaccine

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12
Q

Influenza

A

Orthomyxovirus
Segmented negative sense ssRNA genome
Types A and B cause most disease
Upper respiratory tract, antigenic shift and drift
Spreads through epithelium contained by structure

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13
Q

Polio virus

A 
Picornavirus
Positive sense ssRNA genome
Small unenveloped virus
3 serotypes
2 vaccines available
Fecal oral transmission

Poliomyelitis (paralysis) and muscle weakness
Epithelium -> lymph node -> blood -> muscle, liver spleen -> blood
Then spreads to multiple infection sites

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14
Q

Gram wall in bacteria

A

+ve - 20-80nm peptidoglycan layer, topped by lipoteichoic acid. Highly polar and lipophillic so can resist bile action.
-ve - 5-10nm thick, overlaid by outer membrane

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15
Q

Flagella and pili

A

Independent of ATP
Pili provide protection and attach to other bacteria
Antigen can be changed to avoid recognition, constant and variable pili regions

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16
Q

Arrangement of cocci

A 
Dipplococci in paid
Streptococci in chains
Clusters = staphylococci
2 planes = tetrads
3 planes = sarcinae
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17
Q

Arrangement of bacilli

A

Single rods
Diplobacilli in pairs
Streptobacilli in pairs
Coccobacilli short and wide

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18
Q

Spirochaetes

A

Vibrios- Curved rods
Spirilla- Helical shape and rigid bodies
Spirochetes- helical shape and flexible bodies
Move by axial filaments

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19
Q

Growth phases of bacteria

A

Lag phase
Exponential phase
Stationary phase
Death phase

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20
Q

Targets for anti microbial agents

A

Quinolones which inhibit the unwinding of DNA

Inhibitors of peptidoglycan wall synthesis

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21
Q

Types of staphylococcus
Diseases
Treatment

A

Gram negative
Scalded skin, boils, toxic shock, impetigo
Protein A - interacts with IgG reducing opsonisation
Penicillin, methicillin, vancomycin

Epidermis- device related sepsis e.g. Catheter. Extra cellular slime causes bio films

Saprophyticus- UTI of intercourse, colonises skin and mucosa

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22
Q

Types of streptococcus

A

Gram +ve, pairs and chains,
Pyogenes- URT and skin. Scarlet fever, rheumatic fever and glomerulonephritis
Transmitted by airborne droplets and contact
Treated by penicillin/vancomycin

Agalactiae- neonatal meningitis and septicaemia. Penicillin and gentamicin

Pneumoniae- haemolytic colonies. Pneumonia, septicaemia, meningitis. Capsule protects from phagocytosis. Viral infection may be a precursor, penicillin and vaccine.

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23
Q

Trichomonas vaginalis

A

Causes trichomoniasis, common STD
Multiples by binary fission
Irritation, inflammation, burning although 70% asymptomatic

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24
Q

Giardia intestinalis

A 
Causes giardiasis -> diarrheal disease
Protected by shell to live outside the body, resistant to chlorine
Cysts ingested in food/water
Cyst -> trophozoites -> cysts
Cysts passed in stools
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25
Q

Naegleria fowleri

A

Primary amoebic meningoencephalitis
Cyst -> flagellated trophozoites
Enters with water into nasal mucosa
Migrate to brain via olfactory nerve

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26
Q

Trypanosoma brucei

A

Typanosomiasis
Trypomastigotes enter bite wound
-> amastigotes inside cells
Multiply by binary fission in cells of infected tissues
Changes VSG coat
Inflammation -> winter bottoms sign -> neurological -> coma/death

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27
Q

Entamoeba Histolytica

A 
Acute dysentery, liver abscess, necrotic colitis
GI tract -> liver
Ingested or blood stream
Cysts -> trophozoites
Divide by binary fusion
Infect brain liver and lungs
WBCs die by necrosis when contacted
80% mortality when abdomen infected
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28
Q

Blastocystis

A 
Parasites Live within GI tracts
Vaculor
Granular
Ameboid (causes symptoms)
Cyst (survives stomach acid)
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29
Q

Cryptosporidium

A

Causes cryptosporidiosis
No drug to deal with infection
Oocysts -> meront -> zygote -> oocysts

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30
Q

Toxoplasma gondii

A

Carried in cats, but can have intermediate hosts
Causes toxoplasmosis
1/3 of population infected, high as 84% in France

Tachyzoites -> bradyzoites -> merozoites -> amastigotes -> trypomastigotes

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31
Q

Plasmodium

A

Causes malaria
Liver cells form schizont -> ruptures
Trophozoites -> rozet -> gametocytes -> sporogenic cycle
Oocysts rupture and restart cycle

Malaria attack, anaemia and rosetting

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32
Q

Trypanosome cruzi

A

Chagas’ disease- romana sign and fever. Chronic phase cardiomyopathy and heart aneurysma. Megaesophagus and mega colon.
Fecal oral
Amastigotes in heart -> trypomastigotes -> bug bite

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33
Q

Leishmania

A

Parasites carried in sand flies
Leishmaniosis
Skin lesion, destroys nose, abdominal swelling

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34
Q

How are fungi classified

A

Growth- filamentous/yeast
Infection- superficial/deep mycoses

Divided into 3 groups:
Obligate- dermatophytes which attack external structures
Soil fungi- tolerate high temps and are dimorphic
Opportunistic saprobes- attack when immunocompromised

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35
Q

Tinea infections

Superficial mycosis

A

Caused by ringworm
Capitis- infects hair, treated by 40% KOH
Tinea corporis- round ring on skin, skin scrapings
Tinea ungium- damaged nails, associated with Candida albicans
Tinea pedis- athletes foot.
High normal flora, cracking, lipophillic and lipophobic bacteria -> smell
S.aureus causes secondary infection and pus
This then causes more infection by E.coli -> necrosis
Colonisation with pseudomonas causing permanent damage and trench foot

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36
Q

Superficial Candidosis

A

Most common is genital by Candida albicans
Chronic mucocutaneous candidiasis, oropharyngeal, oesophaegeal, gastrointestinal and disseminated.
Risk factors- neutropenia and damage of gastrointestinal mucosa, venous catheters, antibacterials, surgery

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37
Q

Tinea versicolour

Superficial mycosis

A

Caused by pityroporon orbiculare
Chronic skin condition
Looks pink-brown un tanned, but white on tanned.

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38
Q

Mycetoma

Superficial

A

‘Madura foot’
Tropics
Granulomatous lesion which is surrounded by a dense fibrous capsule
Muscle tendon and bone eventually destroyed

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39
Q

Chromoblastomycosis

Superficial

A

Raised crusted lesions
Several fungi in soil and wood
Inoculated into skin by minor injury
Warmer areas such as Pacific

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40
Q

Sporotrichosis

Subcutaneous mycosis

A

Sporothrix schenckii
75% lymphocutaneous
Primary inoculation -> painless nodules along lymphatic vessels
Nodules drain the primary lesion

41
Q

Coccidiomycosis
C.immitis
Subcutaneous

A 
C. Immitis growth occurs in 2 phases
- mycelial arthrospore in soil
- spherule endospore in infected tissues
As soil dries they become airborne
Leads to respiratory infection, spherules are formed in lungs
42
Q

Systemic mycosis

C.immitis

A

Respiratory infection -> endobronchiolitis
Pulmonary markings, bronchopneumonia, pleural effusion.
IgG and IgM react

43
Q

Disseminated coccidomycosis
Systemic mycosis
Risk factors

A

Weeks to months of primary pneumonia
Males and African ethnic groups more likely
Depressed cellular immunity
Skin, bones, joints and meninges

44
Q

Microsporidia (phylum)

Systemic mycosis

A

Protozoa classified as fungi -> biochemical and physiologically alike
Affect individuals with low CD4 T cells
Encephalitozoon cuniculi- 2000 proteins in genome
Intestinal- diarrhoea, gallbladder disease
Lungs- cough, fluid in lungs
Can spread to UTI, kidney, brain, pancreas, muscle
Eye infections

45
Q

7 functions of the skin

A 
Support
Temperature
Excretion
Vitamin formation
Sensory function
Pigmentation
Protection
46
Q

Factors that cause variation in the skin microbiome

A

Host physiology
Environment
Immune system
Host genotype (fillagrin susceptibility gene)
Lifestyle
Pathobiology (underlying conditions diabetes)

47
Q

Apocrine gland of skin

A

Scent gland found near sex organs

48
Q

Eccrine gland of skin

A

3 portions:
Acrosyringium
Intradermal duct
Secretory coiled gland

Produces eccrine sweat
ACH -> ion exchanges -> eccrine duct reabsorbes NaCl and HCO3
Sweat passed through acrosyringium and deposited on cell surface

49
Q

Sebaceous gland of the skin

A

Cells detach from basal membrane and fill with lipid
Hurts and sebum is expressed into the hair follicle
Sex hormones -> NaATPase system

Bacteria and skin block sebum from escaping pores
S.aureus causes boils
Tinea versicolour- fat and lipid spreads over skin

50
Q

Acid mantle

A

Sebaceous sac contains fungi and bacteria
Esterases -> convert fat to long fatty acid chains
Cause bacteriocidal skin effect
Sebum + sweat = acid mantle
Lactate buffering systems

Bacteria evade by producing urease

51
Q

Impetigo

A

S.aureus and s.pyogenes

Face in angles of mouth and nose. Yellow crusted scabs.

52
Q

Toxic shock syndrome

A

Tampon use
Fever, hypotension and rash, desquamation of skin
TSST1 exotoxin behaves as a super antigen
Shock + organ damage -> organ failure

53
Q

Lepromatous leprosy

A

Mycobacterium leprae
Live in Schwann cells
Loss of sensation -> ulceration due to injury and tissue loss

54
Q

Tuberculoid leprosy

A

Hypersensitivity reaction
Formation of granulomatous changes within epithelial, lymphocytes and langerhans
Thickening of nose, ears and forehead

55
Q

Describe eukaryotic cells

A 
Bigger than bacterial
True nucleus
Membrane bound organelles
Cytoskeleton
Cell division through mitosis
56
Q

What does the upper respiratory tract contain

A

Nose, sinus, larynx, nasal cavity, ethmoidal air cell

57
Q

Defence mechanisms of the URT

A

Tears, lysosomes, sigA, lactoferrin
Nasopharynx- micro flora, lysozyme, sigA
Lungs- macrophages

58
Q

Diptheria

URT infection

A

Corynebacterium diphtheria, gram +ve
Lysogenised by beta phage- tox genes on phage chromosome
Induces production of EF-2
Prevents elongation of proteins in the ribosomes

Catalytic A peptide transfers ADP ribose from NAD to EF2 and inhibits protein synthesis

59
Q

Middle ear- Otis media

A

New air unable to reach middle ear -> Eustachian tube dysfunctions
Body absorbs remaining air creating a vacuum
Negative pressure then fills vacuum with fluid

Inflation of Middle ear, antibiotics

60
Q

Epiglottitis

A

Infection of epiglottis, airway obstruction
Haemophillus influenza type B, rarely strep or pneumococcus
URT -> epiglottis
Bacteria in the blood

61
Q

Parotitis

URT

A

Mumps virus
Respiratory tract -> lymph nodes
Secondary viraemia to the salivary glands, pancreas, sex organs, CNS
MMR vaccine

62
Q

Oral cavity herpes

A

Latent in sensory never ganglia
Cold sores
UV irradiation, dryness and cracking

63
Q

Oral cavity Candidiasis

A

Candida albicans penetrates the epithelium with pseudo mycelia
Treatment with anti fungal agents

64
Q

Viral infections of the LRT

A

Invade bronchiolar epithelium, can spread to alveoli -> pneumonia
Affected cells congested and haemorrhagic
Hyaline membranes
Bacterial infection may also develop

65
Q

Bacterial infections of the LRT

Pneumonia

A

Streptococcus pneumoniae
Lodges in bronchioles, outpour of protein rich fluid in alveoli

Stages of infection
Congestion- vascular engoregement and bacterial proliferation
Red hepatisation- air spaces filled with polymorph nuclear cells, extravasation of RBCs
Grey hepatisation- accumulation of fibrin, disintegration of WBCS and RBCs
Resolution- resorption of the exudates

66
Q

Bacterial infections of the LRT

Tuberculosis

A

Nearly 1/3 of world population
Initial infection- positive skin test, dormant
Activation after immunosuppression

67
Q

Fungal infection of the LRT

A

Aspergillus -> farmers lung
Grows in cavities from TB
Fungal ball invades tissues
Surgery to remove

68
Q

Upper tact bacteruria

A

Bacteria in urine collected from the renal pelvis or ureter

Organisms present in Both in vesicouretic reflux

69
Q

Acute bacterial pyelonephritis

A

Acute infection of the kidneys accompanied by fever, loin pain, pyuria, bacteriuria and bacteraemia

70
Q

Chronic bacterial pyelonephritis

A

Chronic inflammation of renal and tubular tissue with scarring and shrinkage, interstitial fibrosis
Loss of GFR and ability to concentrate urine

Caused by
Bacterial infection
Vesico ureteric reflux
Intra renal reflux

71
Q

Bacterial causes of UTIS

A

Gram -ve rods from GI tract
E.coli (P antigen)
Proteus, pseudomonas, enterobacter
Staphylococcus, chlamydia

Have fimbriae which bind to glycoproteins and glycolipids
P antigen- blood group marker on UT cells

72
Q

Virulence factors in UTI

A

Fimbriae- agglutinate RBCs, can bind to UT wall
Glycocalyx- capsules, slime layers. Reduce adhesion to phagocytes and antibodies. Sialic acid prevents complement activation

73
Q

Staphylococcus saprophyticus in UTI

A

Strong adherence, found in feet.

Associated with hormone activity

74
Q

4 types of urine sample

A

Mid stream- sample taken after initial urination
Catheter- sample from later flow
Supra public aspiration- patient unable to give clean catch
Early morning- used for culture

75
Q

Protective mechanisms of the vagina

A

Acid ph
Lactobacilli
Yeast
IgA

76
Q

Formation and maintenance of normal flora in vagina

A

Glycogen levels at birth increases lactobacilli
Enterococci and coli form appears
At puberty glycogen raised again
At menopause glycogen decreases

77
Q

Herpes simplex

A

Type 2 70-90%
Lesions and burning after 1 week
Painful urination, walking and sitting
Virus then latent, inflamed lesions when activated. No cure.

78
Q

Gonorrhoea

A

Neisseria gonorrhoea, gram -ve diplococci
Pain during urination, discharge
Mainly asymptotic in women
-> pelvic inflammatory disease
Scar tissue in ducts
Newborns develop gonococcal Neoopthalmia -> blindness

79
Q

Syphilis

A

Treponema pallidum
Primary- sores
Secondary- skin rash and mild fever -> latent
Tertiary- extensive tissue damage, paralysis, insanity, death
Resistance to antibiotics increasing

80
Q

Anaerobic vagiosis

A

Gardnerella vaginalis
Grayish thin discharge
Odour when vagina ph alkaline by aromatic amines

81
Q

Thrush

A

Candida albicans
Clumping discharge
Redness, swelling

82
Q

Scabies

A

Mite sarcoptes scabiei
Itching due to allergic reaction
Rash of raised spots

83
Q

Viral meningitis

A

More common, less serious
Herpes simplex, mumps, enteroviruses, HIV
Main cause is the coxsackie virus found in sewage polluted water

84
Q

Bacterial meningitis

A

Haemphilus influenzae b- grows in presence of haematin and NAD. Vaccine avaliable.

Neisseria meningitis- petechiae, fever, headache, stiff neck
Often part of throat flora
Can kill in hours
Meningococcal vaccine but not against B strain

85
Q

Chronic meningitis

A

Damage to skull
Brain abscesses
Mass puts pressure on brain tissue

86
Q

Conjunctivitis

A

Inflammation of conjunctiva

S.aureus, influenza, pneumonia. Caused in newborns by mother infected with STI

87
Q

Keratitis

A

Inflammation of cornea
After injury

Acanthomoeba keratitis- using tap water to clean contacts

88
Q

Endopthalmitis

A

Common after cataract surgery, s.epidermis

89
Q

Blepharitis

A 
Inflammation of eyelids
Burning, itching
Staphylococcal
Seborrheic
Meibomiam gland dysfunction
90
Q

Canaliculitis

A

Uncommon unilateral infection
Candida albicans aspergillus
Removal of necrotic material

91
Q

Host defences of GI tract

A

Normal flora- 400+
Abnormal colonisation of upper GI tract by e.coli and Vibro cholera. Resident bacteria produce bacteriocins which inhibit abnormal flora,
Antibiotics can alter flora
Salmonella and Shigella.

92
Q

Diseases causes by overgrowth of GI flora

A

Clostridium difficile- colon inflammation and diarrhoea. Caused by antibiotics.

93
Q

Gastric acidity

A

People with achlorydria have excessive numbers of microbes in the upper bowel.

94
Q

Norwalk virus GI

A

Vomiting, cramps and diarrhoea, fever, headache

Associated with shellfish

95
Q

Campylobacter sp. GI

A

Diarrhoea, pain, fever
Undercooked meat
Relapses may occur

96
Q

Salmonella and GI

A

Infection in lining of small intestine
Some people carry for 1 year +
Food storage, lizards, infected family

97
Q

Shigella and GI

A

Nom motile gram -ve
Invades the intestinal mucosa
Micro abscesses -> large
Fever, cramps, dysentery

98
Q

Enteroparasites and GI

A

Entamoeba Histolytica
Dysentery, mucus and blood
Cysts in stools
Areas of epithelium area sloughed off as it burrows

Infection And Immunity (2 decks)

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