Gram Negative Bacteria Flashcards
Describe Neisseria Meninigitis?
Cocci
Causes meningitis which is the inflammation of meninges and septicaemia.
Describe Nesseria Gonorrhoeae?
Cocci
Causes urethritis in men
Causes pelvic inflammatory disease in women
Spread by sexual contact
Describe Morexella Catarrhalis?
Cocci
Causes respiratory tract infections
What are coliforms?
Organisms which are in the Enterobacteriaceae family.
Mainly commensals of the human large intestine.
Describe Escherichia coli?
Bacilli
Several virulence mechanisms- pili, capsule, ends/exotoxins.
Ferments lactose
Causes UTIs and diarrhoea (can be bloody)
Describe Salmonella spp?
Bacilli
Does not ferment lactose
Causes diarrhoea
Can be invasive
Describe Salmonella typhi?
Bacilli
Distinct from enterica
Causes typhoid fever/constipation
What are some other common coliforms?
Shigella spp.
Klebsiella spp.
Proteus spp.
Describe Campylobacter spp.?
Curved bacilli Domestic origin from chicken and animals likes low oxygen levels Transmitted via faecal-oral route Causes diarrhoea
Describe Helicobacter pylori?
Curved bacilli
Natural habitat in human stomach
Can cause damage to mucosa and stomach ulcers
Risk of gastric adenocarcinoma
Describe Haemophilus influenzae?
Cocci-bacilli mix
Causes respiratory tract infections.
Describe Pseudomonas spp.?
Curved bacilli
Water and soil coloniser
Multi drug resistance
Causes UTIs, bacteriaemia and rarely pneumonia.
What are anaerobes?
Bacteria that live in the absence of oxygen.
Describe Bacteroides fragilis?
Anaerobe
Part of normal colonic flora
May cause intra-abdominal abscesses.
What are some oral anaerobes?
Prevotella
Porphyromonas
Pasteurella spp
Capnocytophyga spp
What are some bacteria that can’t be stained using Gram’s Method?
Mycobacterium spp.
Spirochaetes
Chlamydia
What causes tuberculosis?
Mycobacterium tuberculosis
Describe Mycobacterium leprae?
Can’t be gram stained
Cannot be cultured
Attacks peripheral nerves
What are Spirochaetes?
Long, spiral-shaped bacteria.
Not easily visualised by light microscopy.
Very difficult to culture (never Treponema pallidum).
Dark ground microscopy or immunofluorescence.
Often diagnosed by serology
Cannot be gram stained.
What are some common spirochaete diseases and the organisms that cause them?
Treponema pallidum - Syphilis
Borrelia burgdorferi - Lyme disease
Leptospira interrogans- Leptospirosis
What is syphilis ?
Primary - skin lesions
Secondary - systemic infections and rash
Tertiary- central nervous sytem infection
What is Lyme’s disease?
Transmitted by ticks
Primary- skin rash at site of bite
Secondary- systemic illness months later when patients exp. cardiac or neurological symptoms.
Tertiary- Chronic disease, occurring years later when patients present with chronic skin, nervous system or joint abnormalities.
Describe Chlamydia trachomatis?
Can’t be gram stained.
Causes tropical eye infections and genital and neonatal infections.
Commonest STI in UK
Can cause pelvic inflammatory disease and infertility in women.
