Microbiology Flashcards
What are the different types of helminths?
Nematodes (roundworms) - intestinal, larva migrans, tissue (filaria)
Trematodes (flatworms, flukes) - blood, liver, lung, intestinal
Cestodes (tapeworms) - invasive and non-invasive
What are the general features of helminths?
Rare in the UK - most cases are imported
Cannot reproduce without a period of development outside the body which involves specific environmental conditions, animal host and/or vectors.
The total worm burden cannot increase without contrast re-exposure to infection in humans.
Some cannot adapt fully to the human host so never develop into adults within the human.
What is the pre-patent period in relation to helminths?
The interval between acquiring infection and the appearance of eggs/larvae in the stool.
What are intestinal nematodes?
Soil-transmitted
All transmitted via eggs or larvae
The egg or larvae is not usually infectious when first passed and has to undergo a period of development in the soil.
Faecal-oral spread
What are the features of Ascaris lumbricoides?
large roundworm
15-30cm long Mainly in the tropics Lives a year or more Pre-patent period is 60-75 days Children particularly prone to infection Adult worms in the small intestine, female lays 200,000 eggs a day, eggs hatch and invade the mucosa of the small intestine, juveniles migrate to the lung, break out in alveoli, swallowed and return to SI.
What are the signs and symptoms of Ascaris lumbricoides? (large roundworm)
- Loeffler’s syndrome: associated with larval migration through lungs, 10-14 days after infection commenced, cough, fever, CXR infiltrates, wheeze
- Effects of adult: often asymptomatic, otherwise mainly mechanical (intestinal obstruction, biliary/pancreatic duct obstruction, appendicitis) or malnutrution
- Odd presentations: emerging from eardrum, nose, mouth, anus
What is the treatment for Ascaris lumbricoides? (large roundworm)
Piperazine, Pyrantel, Mebendazole, Levasimole
What are the features of the hookworm?
Two species, similar in the disease they cause
Ancyclostoma duodenale - asia, mediterranean, middle east
Necator americanus - americas
Small white worm, 1cm, PPP 40-100 days
What is the life cycle of hookworms?
Adults attach the mucosa of the duodenum and jejunum (sometimes ileum). Female produces eggs which pass into the soil via faeces. Hatch after 24 hrs and develop into infectious filariform larvae after 5-10 days. They penetrate exposed skin and migrate to the lungs. They break out into alveoli, swallowed and mature in SI.
What are the clinical features of hookworms?
- Ground itch: at sight of entry of larvae
- Mild pulmonary symptoms due to pulmonary migration
- Common cause of iron-deficiency anaemia
How do you diagnose roundworms?
See emergence of the worm with or without a gastroscope
Stool microscopy for eggs
How do you diagnose hookworms?
Stool microscopy for eggs
How do you treat hookworms?
Iron supplements, pyrantel, mebendzole
What is enterobius vernicularis? (pinworm/threadworm)
Very common in the UK
5-10 mm long, lives fo 56 days, PPP 40 days
Ingested eggs go straight into the duodenum where they hatch, mature adults go into caecum, gravid female migrates to anus and at night lays 20,000 eggs on perianal skin at night, eggs embroyate within 4-6 hours causing itching of bottom.
Commonly affects whole families.
Can cause appendicitis, vaginall penetration or even make it to the paranasal sinuses.
How can pinworm/threadworm be diagnosed?
Microscopy of sellotope strip applied to the perianal region
How can pinworm/threadworm be treated?
Mebendazole, Piperazine, Pyrantel
What are the features of whipworms?
Found worldwide, especially in the tropics
2-5cm long, live for about a year, PPP 70-90 days
Adult resides partly buried in the mucosa of the large bowel
What is the lifecycle of whipworms?
Found in the caecum, AC and occasionally throughout the colon.
Eggs pass into soil via faeces.
Embryonation in moist soil takes about 21 days.
Eggs ingested by a suitable host.
Immature larvae hatch from eggs when they reach the small intestine.
Larvae pass into the large intestine after 1 week of development.
Larvae embed in the mucosa via their thin anterior ends, reach sexual maturity and mate.
What are the clinical features of whipworm?
Resident in the large bowel
Often asymptomatic and co-exists with Ascaris lumbricoides
If infectation is heavy: bloody diarrhoea, rectal prolapse, anaemia, wasting, eosinphilia
How to diagnose whipworm?
Stool microscopy for eggs
Worms may be visible of sigmoidoscopy
What is the treatment for whipworm?
Mebendazole, Albendazole
What are the features of strongyloides stercoralis?
Causes strongyloidiasis
Found worldwide
Adult is 2-5mm long PPP 17-28 days
Adult is 2mm long and lies buried in the small intestine mucosa,
What is the life cycle of strongyloides stercoralis?
Small number of eggs laid by female whose head is buried in the submucosa of the SI, eggs hatch immediately and rhabiform larvae are passed into faeces, mature in soil. Penetrate skin and migrate to the lungs, then break out in alveoli, are swallowed and mature in the jejunum.
What are the clincal features of strongyloides stercoralis?
Pruritis are the site of larval entry
Pulmonary symptoms associated with larval migration
Gut symptoms: malabsorption with eosinophilia
Larva currens: skin rashes associated with autoinfection
What is hyperinfection syndrome?
Caused by strongyloides stercoralis
Associated with auto-infection and an immunocompromised state
Diarrrhoea, weight loss, malabsorption, paralytic ileus, peritonitis, bacterial problems
No eosinophils, larvae are found in stools and sputum
What is Larva Migrans?
Caused by toxocaracarius (dog roundworm) and t. cat (cat roundworm).
Eggs are ingested, develop into larvae, invade tissues for 1-2 years, organism develops no further.
Mainly a disease of children
Diagnosis: eosinophilia, serology
Treatment: Mebendazole, Albendazole
What is Ocular toxocariasis?
Larvae become trapped in the retina Granulomatous reaction Retinal mass, blindness Diagnosis: serology/antigen detection, biopsy Treatment: Mebendazole, Albendazole
What is cutaneous larva migrans?
A creeping itchy skin eruption
Due to the dog hookworms ancyclostoma carinum/braziliense
Lesions at sites where larvae penetrate
Contact with dog faeces
Treatment: topical/systemic thiabendazole, topical cryotherapy
What is Anisakiasis?
Acquired through raw fish
Adult ascarids present in the stomach wall of large sea mammals, eggs are passed into the host faeces, hatching juveniles are eaten by marine crustaceans and mature to infective stage, crustaceans eaten by fish, squid or octopus, man becomes dead-end host.
What is Dracunculus medinerusis?
Guinea worm/Medina worm
Adult is up to 100cm long and lives for 1 year subcutaneously
Can emerge through hand, leg, arm, axillae, breast, vagina.
Man swallows cyclops sp. in contaminated wayer, infective larvae are liberated by digestive enzymes and penetrate the gut walls. Larvae develop and occupy subcutaneous tissues, after 1 year female head approaches skin and causes blister, blister bursts and rhabiform larvae discharge through skin into water.
What are the clinical features of Dracunculus medinerusis?
Localised pain and urticaria at site where worm protrudes.
Tetanus, other sepsis.
Other local problems: joint problems, peritonitis
What is the diagnosis and treatment for Dracunculus medinerusis?
Diagnosis: drop of water on ulcer promotes egg release
Treatment: local wind-out worm
Mebendazole to ease extraction of worm
What is Wuchereria bancroftii?
Main cause of elephantiasis
Endemic throughout the tropics
Insect borne
Adults live in the lymphatic system and survive for 20 years.
What is the life cycle of Wuchereria bancroftii?
Microfilariae (L1) ingested by insect vector. First stage larvae develop into infective third-stage larvae (L1 to L2 to L3). Insect vector feeds on human host, L3 moult in human host and mature into adults.
What is the diagnosis and treatment for Wuchereria bancroftii?
Diagnosis: demonstration of microfilaria in blood taken between 11pm-1am, serology.
Treatment: Diethylcanoamazine, Ivermectin
What is Trichinella Spiralis?
Cause of trichinosis: a zoonosis of rats that circulates between rats and various carnivores. Human is dead-end for organism. Larvae encyst in striateed muscle, infected meat is ingested.
What are the clinical features of Trichinella Spiralis?
Usually asymptomatic GI disturbance associated with worm development Fever, headache, cough at 8 weeks Periorbital oedema, haemorrhage Splinter haemorrhages Neurological signs: deafness, encephalitis, fits, focal signs Myocarditis Pneumonitis
What is Taenia saginatum?
Beef tapeworm. Adult is 5-10m long and lives up the 30 years.
PPP 12 weeks.
Caught by eating undercooked beef containing “cysts” encysted larvae
Usually asymptomatic
Proglottids may emerge from human anus
What is the diagnosis and treatment for Taenia saginatum?
Diagnosis: stools for eggs and proglottids
Treatment: Niclosamide, praziquantel
Name some other examples of tape worms (other than Taenia saginatum)?
Echinococcus granulosus - dog tapeworm, causes hydatid disease
Enchinococcus multilocaularis - artic fox tapeworm, mainly in the north of the Northern hemisphere
Diphyllobothrium lactum: fish tapeworm, one of the causes of sparyaresis
Vitamin B12 deficiency
What are flukes?
Blood, liver, lung, bowel fluke
All have a snail as their intermediate host
Schistosoma spp. causes schistamiasis
Adult fluke is 12cm long, lifespan is 3-5 years
Different species in different areas
What is the life cycle of a fluke?
Miracidium hatches from egg, infect first intermediate host (snail), cercariae leave snail and penetrate skin of human in water, immature worm enters bloodstream, ends up in vein near intestine or bladder, reach sexual maturity in veins of abdominal cavity, enter intestinal tract, passed through urine/faeces.
What is Schistosoma haematobium?
Adults live in the liver, eggs migrate to the bladder.
Granulomatous lesions - may cause obstructive uropathy - reversible if of short duration and treated
Calcified bladder
Squamous cell baldder cancer
Kidney stones
What is a pathogen?
Organisms that cause or are capable of causing disease
What is a commensal pathogen?
Organisms which colonise the host but don’t normally cause disease
What is an opportunist pathogen?
Microbe that only causes disease if host defences are compromised.
What is virulence/pathogenicity?
The degree to which a given organism is pathogenic
What is asymptomatic carriage?
When a pathogen is harmlessly carried at a tissue site where it causes no disease
What are the parts of the bacteria name?
First name is genus
Second name is species
What are the different types of bacterial morphology?
Coccus (round) - diplococcus, chain of cocci, cluster of cocci
Bacillus (rod) - chain of rods, curved rod, spiral
Exceptions such as spiral (spirochaetes)/combinations of both
What are the structural features of the bacteria?
Bacterial cell wall - can have one or two cell walls
One chromosome of circular double stranded DNA
Capsule protects the bacteria from the host
Flagella enables movement
Pilli help them attach and colonise the host
What is the Ziehl-Neelsen stain?
Used to identify acid-fast organisms, mainly mycobacteria. Acid-fast bacteria are composed of mycolic acid in their cell wall, they are stained pink by pink by carbol-fuchsin.
What’s the structure difference between gram postitive and gram negative bacteria?
Gram positive has a single peptidoglycan bilayer and capsule.
Gram negative has an inner memebrane, peptidoglycan layer, outer membrane, lipopolysaccaraide layer and a capsule.
What are spores?
Spores are a hardened structures that is resistant to hard chemicals and attack.
Contains all DNA.
Remain like this until the environment is satisfactory.
Only killed in autoclave.
What are the boundaries for bacterial environment?
Temperature
How can you study bacteria growth?
Can be grown on a rich broth or agar plate
Different bacteria have different doubling times
Can be followed by looking at light absorption or by counting bacteria
What is an endotoxin?
Component of the outer membrane of bacteria
e.g. lipopolysaccharide in gram-neg bacteria
Non-specific action
Stable under heat
Weak antigenicity
No convertibility to toxoid
What is an exotoxin?
Secreted proteins of gram positive and gram negative bacteria. e.g. stop macrophages taking over Specific action Labile under heat Strong antigenicity Convertibility to toxoid
What are the features of bacterial genetics?
Usually a single chromosome (dsDNA)
Quite promiscuous - swap DNA over a lot
RNA polymerase converts mRNA into protein
Mutations can occur - base substitution, deletion, insertion (antibiotic resistance)
Contain plasmids which can transfer from one bacteria
What is bacterial conjugation?
DNA is transferred from one bacterium to another. The donor cell pulls itself close to the recipient using its pilus, DNA is then transferred (usually as a plasmid).
What is bacterial transformation?
Bacterium takes in DNA from its environment. If DNA is in form of a plasmid, it can be copied in the receiving cell and passed on to its descendents.
What is bacterial transduction?
Viruses that infect bacteria (bacteriophage) move short pieces of chromosomal DNA from one bacterium to another.
What are the two ways bacteria can grow?
Obligate intracellular bacteria (must be grown in hosts) e.g. Rick elysia, Chlamydia, Coxiella
Bacteria that can grow on artificial media (may have a cell wall or not).
In which morphology will bacteria grow?
Bacteria with a cell wall may grow as single cells or as filaments.
Single cells - rods, cocci, spriochaetes
Filaments - actinoyces, nocardia, streptomyces
Which cocci are gram pos and gram neg?
Cocci can be gram negative: veillonella (anaerobic) or neisseria (aerobic)
Cocci can be gram positive: staphlococcus and streptococcus (aerobic) or peptreptococcus (anaerobic)
What are the types of Streptococcus?
B-hemolytic (S.pyogenes, S.agalactiae) - tonicilitis
a-hemolytic (S.pneumoniae) - endocarditis
Non-hemolytic (S.bovis)
Which rods are gram pos and gram neg?
Gram positive rods can be anaerobic like clostriduym and propionibacterium.
Gram positive rods can also be aerobic like corynebacterium, listeria and bacillus.
Gram negative rods can be anaerobic like bacteroids.
Gram negative rods can be aerobic like coliforms (escherichia, salmonella), pseudomonas (P.aeruginosa), Vibrio (cholerae, campylobacter, helicobacter), Parvobacteria (haemophilus, brucella).
What are the features of staphylococcus?
At least 40 species
Can be coagulase +ve or -ve (coagulase is an enzyme produced by bacteria that clots blood plasma, providing protection from phagocytosis)
Staph. aureus is most important (coagulase +ve)
Coagulase -ve are important opportunistic pathogens
What are the features of Staph. aureus?
Gram-positive bacteria
Spread by aerosol and touch
There are carriers and shedders
MRSA is a resistant strain transferred by MecA strain.
Resistant to B-lactams, gentamicin, erythromycin, tetracycline.
What are virulence factors?
Pore-forming toxins
Insert itself into host cell membranes, causing pores and leakage of cell contents.
e.g. Proteases - exfoliatin attacks desmosomes in skin
Toxic shock syndrome stimulates cytokine release
Protein A binds Igs in the wrong orientation
Name two important coagulase negative staphylococci?
S.epidermidis - infections in catheters/prostheses
Form persistent biofilms
S.saprophyticus - acute cystitis
Use haemagglutin for adhesion
What are the different types of haemolysis?
a-haemolysis: Partial. Release water which reacts with Hb.
B-haemolysis: Complete. Produce haemolysins O and S, bursting open RBCs.
Non or Y haemolysis: No lysis
How can streptococci be classified?
Can be classified by haemolysis, lancefield typing or by biochemical properties.
What is lancefield typing?
A method of grouping catalyse negative bacteria based on their bacterial carbohydrate cell surface antigens.
Antiserum to each group is added to a suspension of bacteria, clumping indicated recognition.
What are the streptococci groups in lancefield typing?
Carbohydrate cell surface antigens: Lancefield A-H and K-V.
Group A: S.pyogenes (very important pathogen!)
Group B: S.agalactiae (important in neonatal infections)
What are the illnesses caused by Strep. pyogenes?
Gram-positive bacteria Very sucessful pathogen Cellulitis as a result of wound infections Tonsillitis Pharyngitis Impetigo (skin infection) Scarlet fever
What are the complications of Step. pyogenes?
Rheumatic fever - inflammatory disease of heart, joints, skin, brain. Often follows a Strep throat infection
Glomerulonephritis - inflammatory disease somemtimes following S. pyogenes infection
What is an Anti-SLO titre?
Anti-streptolysin O (ASO or ASLO) is the antibody made against streptolysin O, a streptococcal hemolytic exotoxin produced by most strains of group A and many strains of groups C and G Streptococcus bacteria.
Streptococcal exoenzymes are bound to biologically inert latex particles. If Streptococcal antibodies are present in the test sample, reaction occurs (agglutination).
What are the virulence factors of S. pyogenes?
Exported factors - to aid with spreading
Toxins - for adherence and exaggerated immune response
Surface factors - for protection and encouraging complement degradation
What are the features of S. pneumoniae?
Gram-positive bacteria
Normal commensal in oro-pharynx in 30% of population
Causes pneumonia, otitis media, sinusitis, meningitis
Predisposing factors:
- Impaired mucus trapping (viral infection)
- Hypogammaglobulinaemia (immunocompromised)
- Asplenia (removal of spleen)
What are the virulence factors of S.pneumoniae?
Capsule - antiphagocytic
Inflammatory wall constituents like teichoic acid and peptidoglycan
Cytotoxin - inserts into the host cell membrane
What are viridans streptococci?
Gram positive bacteria Collective name for oral streptococci a or non-hemolytic Important in infective endocarditis Cause dental caries and deep organ abscesses e.g. brain and liver.
What are the features of C.diphtheriae?
Gram positive bacteria
Droplet spread
To isolate, use the presence of potassium tellurite
Its toxin inhibits protein synthesis
Infection prevented by vaccination (toxoid-inactivated toxin)
What is the lipopolysaccaride of a gram neg bacteria made up of?
Lipid A - toxin portion that is anchored in the outer leaflet of the outer membrane
Core (R) antigen - short chain of sugars, some are unique to LPS
Somatic (O) antigen - highly antigenic repeating chain of oligosaccharides
What are the virulence factors of gram-negative bacteria?
Any product or strategy that contributes to pathogenicity.
Colonisation factors - adhesins, invasins, nutrient acquisition, defence against the host
Toxins - ‘effectors’ usually secreted proteins that cause damage and subversion
What are the features of proteobacteria?
AKA enterobacteria
Gram negative bacteria
Rods
Most are mobile
Facultatively anaerobic (an aerobe that can switch to work in anaerobic conditions)
Some species colonise the intestinal tract
What are the cell surface antigens of Gram negative bacteria?
H antigen (flagellum) K antigen (exopolysaccharide 'capsule') O (somatic) antigen
What is serotyping?
Serotypes refer to separate groups within a species of a microorganism that all share a similar characteristic but have different antigens.
You can mix the sample with blood containing antibodies (antiserum) leading to agglutination.
What are the features of E.coli?
Gram negative bacteria Commensals - most abundant facultative anaerobe Peritrichous flagella (all over!) Causes... Wound infections UTIs Gastroenteritis Travellers' diarrhoea Bacteraemia Meningitis
Why are some strains of E.coli pathogenic?
There are several different pathovars with distinct pathogenic strategies.
Common ‘core genome’ with additional acquisition of pathogenicitity genes ‘en bloc’ through lateral gene transfer.
What is ETEC?
Enterotoxigenic Escherichia coli
Gram neg bacteria
Leading cause of diarrhoea
Have pilli which allow for attachment in the intestines
Diarrhoea symptoms caused by disruption of tight junctions and effects on ion secretion.
What are the features of Shigella?
Gram neg bacteria
Four species
Produce shigatoxin
Cause severe bloody diarrhoea (>30/d), cramps, pain and fever
Person-to-person, or contaminated water or food
Entry through colic M cells
Invasion of the colonic mucosa
Takes over cell’s actin to move through more tight junctions.
What are the virulence factors of Shigella?
Catalytic subunit (glucosidase) - cleaves N-glycosidic bone of adenosine residues in rRNA Receptor binding subunits
What are the complications of Shigella?
Systemic absorption of shigatoxin targets the kidney.
Causes microvascular thrombosis leading to kidney failure.
What are the two main species of salmonella?
S. enterica - responsible for salmonellosis
S. bongori - rare (contact with reptiles)
What are some of the infections caused by Salmonella enterica?
Gastroenteritis/enterocolitis - frequent cause of food poisoning, localised infection, usually resolves within 7 days
Enteric fever - typhoid, systemic disease
Bacteraemia - uncommon
What is the pathogenesis of salmonella?
Ingestion of contaminated food/water
High infective dose
Invasion of gut epithelium in small intestine
Intestinal secretory and inflammatory response
Does not produce toxins
Transcytosed to basolateral membrane, enters submucosa
Intracellular survival/replication
What is the pathogenesis of enteric (typhoid) fever?
Ingestion
Incubation period (1-3 weeks)
Asymptomatic
Once titre has increased enough in the bloodstream, you begin to get symptoms.
Multiplication occurs in liver, spleen and bone marrow.
What is Proteus mirabilis?
Gram neg bacteria Enterobacteria Opportunistic Causes UTIs, pyelonephritis, septicaemia Virulence factors: urease (increased pH), can lead to kidney stores
What is Klebsiella pneumoniae?
Gram neg bacteria
Enterobacteria
Opportunistic
Infections in neonates, elderly, immunocompromised.
Benign colonisation of GIT and oropharynx
Can lead to UTIs, pneumonia, surgical wound infections, sepsis.
What is vibrio cholerae?
Gram negative
Facultative anaerobic
Lives in saline environments
Spread through ingestion by shellfish or contamination of drinking water due to the flooding of coastal areas or poor sanitation.
What is cholera?
Most severe diarrhoeal disease Characterised by pandemics Faecal-oral route (not person-to-person) High infective dose required Spread through faecal contaminated water or undercooked shellfish Incubation hrs-5 days Can lose 20 litres fluid/day plus electrolytes - dehydration and death No blood, pus or fever Treated with oral rehydration therapy.
What are the virulence factors of vibrio cholerae?
Toxin coregulated pili
Cholera toxin
What is pseudomonas aeruginosa?
Gram neg bacteria
Ubiquitous, free-living aerobe
Opportunistic (serious cause of nosocomial infections)
Multiple antibiotic resistance (and disinfectants) making it difficult to treat.
What infections does pseudomonas aeruginosa cause?
Localised: Burn/surgical wounds UTIs Keratitis Systemic: Sepsis in neutropenic patients (leukaemia, chemotherapy, AIDs) Chronic: Cystic fibrosis patients
What are the virulence factors of pseudomonas aeruginosa?
Multiple toxins but the main ones are…
Exoenzyme S and Exoenzyme O - inteferes with cell signalling
Exotoxin A, LasB elastase, PlcH phosphatase - involved cell death/damage.
What is Haemophilus influenzae?
Gram negative bacteria
Exclusively a human parasite
Carried in nasopharyngeal carriage in 25-80%
Opportunistic infections seen mainly in young children and adult smokers.
Can cause meningitis, bronchopneumonia, epiglottitis, sinusitis, otitis media, bacteraemia, pneumonia in CF, COPD and HIV patients.
Will not grow on blood agar but will grow on chocolate agar.
What are the virulence factors of Haemophilus influenzae?
Capsule - the invasive ones are encapsulated (6 serotypes) but the commensal ones are not
Allow for penetration of nasopharyngeal epithelium
LPS ‘endotoxin’ - inflammation and complement resistance
What is Legionnaire’s disease?
Severe inflammatory pneumonia
Caused by legionella pneumophilia
Found in man-made aquatic environments - air-conditioning, shower heads, nebulisers, humidifers)
Occurs in the immunocompromised (elderly, alcoholics, smokers)
What is the action of legionella pneumophilia?
Infected by flagellated form
Modulates trafficking of the phagosome
Differentiate to the non-flagellated form
Upregulates pro-inflammatory genes in alveoli
What is Bordetella pertussis?
Gram negative Causes pertussis (whooping cough) Short rods Non-invasive Highly contagious, aerosol transmission Non-specific flu-like symptoms followed by paroxysmal coughin
What are the toxins produced by Bordetella pertussis?c
Pertussis toxin - increased cAMP
Adenylate cyclase-haemolysin toxin - suppression of innate immune functions
What are Neisseria bacteria?
Gram negative bacteria Non-flagellated diplococci Two species: - N. meningitidis - N.gonorrhoeae
What is Neisseia meningitidis?
Gram negative bacteria
AKA meningococcus
Present in nasopharynx of 6-10% population
Rises to 20-90% in outbreaks
Aerosol transmission
Cross nasopharyngeal epithelium and enters blood
Can cause low level bacteraemia or septicaemia
Meningitis - bacteria enter the CSF of subarachnoid space
What are the virulence factors of Neisseia meningitidis?
Capsule - anti-phagocytic
LPS (membrane ‘blebs’) - cytokine cascade and sepsis
What is Neisseia gonorrhoeae?
Gram negative bacteria
AKA gonococcus
Person to person transmission
Can be asymptomatic
Can cause urethritis with additional infection of proctitis, gingivitis, pharyngitis.
Complications: salpingitis (fallopian tubes) or PID
What are the virulence factors of Neisseia gonorrhoeae?
Twitching motility - grabbing hook model
LPS - inflammatory response
What are campylobacter?
Gram negative bacteria
C.jejuni and C.coli
Spiral rods
Unipolar or bipolar flagella
Most common cause of food poisoning from poultry and cattle
Mild to sever diarrhoea, often with blood
Usually self-limiting (<1 week).
What is helicobacter pylori?
Microaerophilic (requires CO2)
Spiral
Present in 50% of population
Major role in gastritis and peptic ulcer disease (80-90% ulcers)
Implicated in 10% of gastric adenocarcinoma and muscosa-associated lymphoid tissue lymphoma
What are bacteroidetes?
Gram negative bacteria
Non-motile rods
Strict anaerobes
Commensal flora
Opportunitistic - in tissue injury from surgery, perforated appendix or ulcer
Predominantly peritoneal cavity infections
What are chlamydiae?
Gram negative bacteria Chlamydia and chlamydophila Very small, non-motile Obligate intracellular parasites Many are asymptomatic Cannot culture in bacteriological media
What are the two major types of chlamydiae?
C. pneumoniae - respiratory tract
C. psittaci - mainly birds, psittacosis and severe pneumonia
What are the 3 main strains of chlamydiae?
Trachoma biovar - infectious blindness
Genital tract biovar - infects epithelial cells of urethra and vagina, can ascend to uterus and ovaries
Lymphogranuloma venereum - invasive urogenital or anorectal infection
What are Spirochaetae?
Gram negative bacteria
Helical and highly flexible
Most are free-living and non-pathogenic
Pathogenic varieties are difficult to culture
Modified outer sheath - replaced by a different glycolipid
What is an endoflagella?
Type of flagella that the spriochaete have
Propels bacteria in a corkscrew motion
Swim faster in high viscosity medium
Hides antigenic flagellum
What is Borrelia burgdorferi?
Gram negative bacteria
Causes lyme diseasse
Bacterium infects small mammals
Acquired by tick larvae and transmitted by nymphs
Causes flu-like symptoms and bulls-eye rash
Dissemination via lymphatics/blood to other organs
What is Leptospira interrogans?
Gram negative bacteria
Causes leptospirosis
Contact of mucous membrane or abraded skin with animal urine
Flu-like symptoms
Severe form (Weil’s disease) - jaundice, acute renal and hepatic failure, pulmonary distress, haemorrhage
What bacteria causes syphilis?
Treponema pallidum
What are the 3 stages of syphilis?
1) Localised infecction - ulcer, highly transmissable
2) Systemic (skin, lymph nodes, joints, muscles) 1-3 months post infection, highly transmissable
3) Granulomas in bone and soft tissue, cardiovascular symphilis in aorta, neurosyphilis in brain and spinal cord. Occurs several years post-infection. Non-infectious.