Clinically Relevant Gram Negatives Flashcards
What is meant by strict aerobes?
Will not grow unless their is oxygen.
What is meant by microaerophilic bacteria?
Only require small amounts of oxygen to grow.
What is meant if a type of bacteria is strict anaerobic?
Cannot grow in oxygen at all.
Can be toxic.
Give an example of a strict aerobic gram negative bacteria.
Legionella sp.
Give an example of a gram negative cocci.
Neisseria
->either Neisseria gonorrhoea or Neisseria meningitis).
Name th large group of bacilli gram negative bacteria.
Coliforms
What are the two subdivisions of coliforms in the gut.
Gut pathogens
Gut commensals.
Name some bacteria found in the gut which colonise.
E.coli
Klebsiella
Name some bacteria found in the gut which can be disease causing pathogens.
Salmonella
Shigella
Describe the structure of the two types of microaerophilic bacilli.
-Small curved bacilli, such as campylobacter sp
-Spiral bacilli such as Helicobacter sp
Is they type of bacteria which is strict anaerobic cocci or bacilli?
Bacilli.
What are the two major genus’ of gram negative cocci?
Neisseria sp
Moraxella catarrhalis
What can Neisseria sp gram negative bacteria lead to?
Meningitis.
What is meningitis?
Inflammation of the meninges and often get associated septicaemia (blood poisoning).
Life threatening disease.
What would be important when trying to diagnose meningitis?
Blood cultures and CSF.
What does Neisseria gonorrhoeae cause?
Gonorrhoea.
What can occur in men with Gonorrhoea and women with Gonorrhoea?
Causes urethritis in men and pelvic inflammatory disease in
women
How is Gonorrhoea spread?
Sexual transmission.
Give an example of a gram negative coccus which is a causative agent of respiratory tract infections
Moraxella catarrhalis.
Moraxella catarrhalis is particularly prevalent in individuals with?/
Underlying lung pathology.
Define coliforms.
–Organisms which are in the family Enterobacteriaceae.
They colonise the gut.
Beneficial but can cause disease.
Name some of the virulence mechanisms of E.Coli.
Pili, capsule, endotoxin and exotoxins.
What can E.Coli. ferment?
Lactose.
What can E.coli cause?
UTI
What is Enterotoxogenic E.coli?
One of the most common bacterial causes of diahorrea.
Antibiotics can sometime make E.Coli worse…why?
Stimulates more toxin production.
What can Enterohaemorrhagic E.coli give rise to?
Bloody diahorrea.
How is Salmonella distinct from E.Coli?
Does not ferment lactose.
What is Salmonella Typhi the cause of?
Typhoid fever.
What are some symptoms of typhoid fever?
Fever and constipation in the early stages.
How can Salmonella Typhi be diagnosed in a lab?
Using blood cultures and faeces specimens.
What does the coliform Shigella spp cause?
Cause of diarrhoea, dysentery – in UK usually travel related.
What does the coliform Klebsiella spp cause?
– Cause of UTI and hospital acquired pneumonia.
What does the coliform Proteus spp cause?
– Causes UTI – often associated with stones.
What is the source of the Curved Gram Negative bacilli, Campylobacter spp?
Chickens and other domestic animals.
How is Curved Gram Negative bacilli, like Campylobacter, spp.
spread?
Spread via faecal-oral route
What is the most common cause of bacterial diahorrea in the UK?
Campylobacter spp.
Name one common type of Curved Gram Negative bacilli.
Campylobacter spp.
Describe Helicobacter pylori
- Curved rods.
- Natural habitat is human stomach.
3.Damages mucosa and causes ulcers.
4.Strong risk factor for gastric adenocarcinoma
Give an example of a gram negative bacteria which is Cocco-bacilli.
Haemophilus influenzae
What does Haemophilus influenzae cause?
Respiratory Tract Infection.
Where can the gram negative bacillus Pseudomonas spp colonise?
Sinks, mops, drains as is a water and soil coloniser.
What is a danger of Pseudomonas spp?
May contaminate medical equipment.
What is Pseudomonas spp responsible for?
Hospital acquired infections such as UTI, septicaemia, bacteraemia.
Pseudomonas spp is particularly feared in individuals with what condition?
Cystic Fibrosis.
What are gram negative anaerobes usually a part of?
Polymicrobial infection.
Name some gram negative anaerobes.
- Bacteriodes spp.
- Prevotella
- Porphyromonas
What is Bacteroides fragilis and what does it cause?
- Part of normal colonic flora.
- Causes intra-abdominal abscess.
- May spread to other sites.
Name one of many oral anaerobes.
Prevotella
What are Miscellaneous bacteria?
Bacteria which aren’t stained gram positive or gram negative.
Why will some bacteria cells not be stained by Gram’s stain?
Gram’s stain targets the cell wall and some cells have a different composition.
Give three examples of bacteria that do not get stained by Gram’s stain.
– Mycobacterium spp.
– Spirochaetes.
– Chlamydia / Chlamydophila.
Name a group of bacilli which do not get stained by Gram’s stain.
Acid and alcohol fast bacilli.
Which type of staining can you use to stain acid and alcohol fast bacilli, like mycobacteria?
Ziehl-Neelsen (ZN) or Auramine
What disease can be found using Ziehl-Neelsen (ZN) or Auramine?
TB
How quickly does mycobacteria grow?
Very slowly.
->2-4 weeks
What disease does TB often occur alongside?
HIV
Describe Spirochaetes
Miscellaneous bacteria (not included in any other pathogenic groups, are not commonly isolated but may cause disease).
Long, spiral-shaped bacteria.
* Not easily visualised by light microscopy.
* Very difficult to culture
What techniques can be used to see Spirochaetes?
Dark ground microscopy or immunofluorescence.
Name two diseases caused by Spirochaetes.
Lymes disease or Syphillus.
How many stages of syphillus are there?
Four-
primary, secondary, latent and tertiary.
Describe the primary stage symptoms of syphillus.
Non-painful skin lesion (chancre) at the site of infection (skin or mucous membranes)
Describe the secondary symptoms of syphillus.
generalised systemic illness and rash
(6-8 weeks after primary symptoms):
Describe the latent phase symptoms of syphills.
Symptomatic episodes may occur
Describe the tertiary stage symptoms of sypillus. (usually a few years after the onset).
Danger with central .nervous system
What is Lyme’s disease transmitted by?
Ticks
Describe the three stages of Lyme’s disease.
Stage 1: Skin rash (erythema chronicum migrans) appears at the site of
the tick bite.
* Stage 2: Systemic illness occurs in some patients
weeks or months later when patients suffer cardiac
or neurological and musculoskeletal symptoms
* Stage 3: Chronic disease, occurring years later when patients present with
chronic skin, nervous system or joint abnormalities
How can Lyme’s disease be diagnosed?
Diagnosed by clinical assessment and serology (antibody detection).
What does Leptospirosis do?
Infects animals and concentrates in the kidneys.
How is Leptospirosis transmitted?
Spread is via infected urine and other body fluids and
tissues (zoonosis).
Name twi groups hat are most at risk of developing Leptospirosis.
Sewage workers.
Those who take part in watersprots.
Name twi groups hat are most at risk of developing Leptospirosis.
Sewage workers.
Those who take part in watersports..
Describe the symptoms of Weil’s disease, a type of leptospirosis which is caused by the infected urine of rats.
Febrile illness (showing symptoms of a fever) with systemic upset, liver
and renal failure, aseptic meningitis, 10 % mortality.
How do you diagnose chlamidya?
nucleic acid amplification tests (NAAT) on first void urine or
vulval/vaginal swabs.
What can chlamydia lead to?
Pelvic inflammatory disease and infertility in women.
What is the most common STi in the UK?
Chlamidya
