Bacteria Flashcards
Someone comes in with legionnaires disease.
what is this? whart is the causative agent? describe the pathogenesis of this bacteria. what is the class of this bacteria? What is required of the patient and why?
Acute lobar pneumonia
Legionella pneumophilia
pathogenesis: In the lung, alveolar macrophages phagocytose bacteria. However phagosome fails to fuse with lysosome
the bacteria divides in the phagosome until the cell ruptures
patients cared for in a side room because its very infectious
Person has endocarditis following a dental extraction. causative agent found to be catalse negative.
What is the causative agent? Where is it normally found? What type of bactteria is it? What investigations can you do?
Viridans streptococci
normally found in mouth
it’s a gram positive cocci
investigations: Blood agar shows it is alpha-haemolytic so green and as non haemolytic
What are the causative agents of meningitis in neonates, children, young adulta and the elderly?
Neonates: Group B streptococci, Escherichia coli, Listeria
Children: Haemophilus influenzae type B, streptococcus pneumoniae, Neisseria Meningitidis
Young adults: Neiserria Meningitidis, Streptococcus pneumoniae
Elderly: Streptococcus pneumoniae, neiserria meningitidis and listeria
Upper respiratory tract infection. You find that it is a gram negative coccobaccilli
what type of bacteria is this? Normally found? 3 upper resp tract diseases? Three infections it can cause in bloodstream? How is it spread?
Haemophilus influenzae
normal site: Upper resp tract
Upper resp tract- Sinusitis, epiglottitis, bronchopneumonia
bloodstream: Bacterial meningitis (yound people and infants), septic arthritis, cellulitis
spread by resp droplets
Define sepsis and septic shock
Life threatening organ dysfunction due to a disregulated host response to infection
persisting hypotension despite fluid resuscitation
Someone has had a prosthetic implant. You find an infection has arisen on it.
What is the likely causative agent? What type of bacteria is it? Where is it normally found? What is its main virulence factor and what does this do?
Staphylococcus epidermis
Gram positive cocci
Found on the normal flora of the skin
Main virulence factor is Polysaccharide intercellular adhesin that facilitates adhesion to the implant and acts as a barrier to antimicrobials
Someone on holiday. had some bad seafood. BAD diarrhoea.
Causative aagent? Type of bacteria? Normal site? Other diseases it can causes (intestinal and extraintestinal)? Investigations 2? Prevention?
Escherichia coli gram negative rod Gi tract Intestinal: Diarrhoea Extraintestinal: UTI, Neonatal meningitis
Investigations: Difficult to cultured from diarrhoea because expect to be there normally since normally present in the GI tract
However if in a site that is meant to be sterile, significant
Prevention: Care in selectionand preparation and consumption of food and water
A man comes in with cellulitis.
What are the symptoms of cellulitis 3? what are the two causative agents of this? How would you differentiate between these two types?
You find it is Staph Aureus.
What type of bacteria is Staph aureus? What 4 other things can staph aureus cause? Name two virulence factors of staph aureus. What is toxic shock syndrome.
What does the gram stain look like? How would you prevent this microbe?
Symptoms: Expanding erythema, warmth and swelling
Two causative agents: Staphylococcus or Streptococcus
You differentiate between two by doing a catalase test. You find staphylococcus is Catalase positive and streptococcus is catalse negative
Gram positive cocci
4 other things: UTI, Pus filled abscesses with wound infections, Endocarditis (eg from dental extraction) and Pneumonia
Two virulence factors: Capsule and Superantigen exotoxin
Toxic shock syndrome is when there is a massive activation of T cells caussing a cytokine storm leading to multi system disease
Gram stain- Purple, cocci, clustered like grapes
Prevention is just the general infectio control procedures
A person comes in with severe purulent inflammation of the oropharynx and tonsillar area.
What is the causative agent? What is the name of the infection? Where is it normally found? Two other things that it can cause? What post infectious disease can it cause? What type of disease is this and what does it cause? 3 Virulence factors? 2 investigations?
Streptococcus pyogenes
acute pharyngitis
normally foound on the skin and throat
also causes Impetigo ( Lesions on limb and face, a superficial skin infection) and puerperal sepsis (Disease of uterine endometrium leading to purulent vaginal discharge
Rheumatic fever- inflammation of joints and heart valves and is an autooimmune disease
Virilence factors: M proteins: Antiphagocytic and provide the bacteria with variation (Different serotypes of the bacteria
streptokinase: Converts plasminogen to plasmin so breaks down clots
Superaantigenic exotoxin- Toxic shock ssyndrome
Investigations: Β haemolytic so you get small opalescent colonies surrounded by large areas of β haemolysis
also highly sensitive to bacitracin so a low concentration of this will inhibit growth
a child comes in with a stif neck and photophobia and a purpuric rash. Last night he came down with a fever and its gotten much worse.
The same bacteria also causes pneumonia
what is the name of this bacteria? 1 other disease caused by this bacteria? What type of bacteria is it? Where is it normally found? What 4 sort of people are partly susceptible to infection? What can this infection progress to 2? Two virulence factors? 2 investigations? How is it prevented?
Streptococcus pneumoniae
Otitis media
gram positive cocci
normal site is nasopharynx
4 people: alcoholics, asplenic people, malnourished people, immunosupressed people
can lead to fulminant septicaemia and septic shock
virulence factors: Pili for adherence and capsule that is antipahgocytic
investigations: Gram stain: Lancet shaped, purple diplococci
blood agar- its alpha haemolytic so wet and moist and green
prevented with vaccines
Some comes with thyphoid fever. Been travelling
Causative bacteria? Symptoms 7? Incubation period? What three things would investigations find? How is it transmitted? Complications? Prevention?
Salmonella typhi
symptoms: fever, headache, abdo discomfort, constipation, dry cough, brady cardia, rose spots on trunk
incubation period: 7-14 days
Investigations: Moderate anaemia, lymphopenia, raised LFTs
transmitted by faecal-oral
complications- intestinal haemorrhage and perforation
prevention- Typhoid vaccine and food and hygiene precautions
In-Patient. has been given antibiotics and recently has had violent diarrhoea.
Name of the causative agent? Type of bacteria? Where is it normally found? What is the name of the worst type of diarhoea and define this? Two toxins? (One enterotoxin and one cytotoxin). 3 Investigations?
Clostridium difficile
gram negative bacilli
normally found in the colon
name: Pseudomembranous colitis- Inflammation of the colon where you get diarhoea consisting of mucus, fibrin, inflammatory cells and cell debris
Toxins: A and B
A- Enterotoxin causing excessive fluid secretion
B- cytotoxin- disrupts protein synthesis and disorganises cytoskeleton
Investigations: Cultured from stools
Enzyme immunoassays of toxin A and B
PCR
Child with meningitis. You find the bacteria is a gram negative diplococcus
What is the bacteria? Where is it normally found? 5 Symptoms of sepsis? 3 virulence factors? 2 investigations? 2 ways it is prevented?
neiserria meningitidis normally found on the nasopharynx symptoms of sepsis: Large blotchy purple haemorrhages vomiting and diarhoea circulatory collaspe Adrenal necrosis
Virulence factors: Pilus for adherence
capsule- enhanced phagocytosis
endotoxin called Gonococcal lipooligosaccharide (LOS)- Triggers inflammatory response
Investigations: Gram stain- gram negative diplococci, and kidney bean shaped
Also test the CSF for bacteria> Also expect low glucose, high proteins and increased pressure
Prevention: Vaccine and prophylaxis given to family members and anyone in close contact with the patient.
