T1-L1: Bacterial Pathogens Flashcards
Give common gram positive cocci bacteria.
- Staphyloccocus aureus
- Streptococcus pyogenes
- Streptococcus agalacitae
Give common gram negative cocci bacteria.
- Neisseria meningitidis
- Neisseria gonorrhoea
Give common gram positive bacilli bacteria.
- Clostridium dificile
- Bacillus anthracis
Give common gram negative bacilli bacteria.
- Salmonella typhi
- Shigella spp
- Escherichia coli
- Proteus spp
Give common gram positive coccobacilli bacteria.
- Haemophilis
- Bordetella
- Brucella
- Pasteurella
Give common gram negative coccobacilli bacteria.
- Heliobactor
- Camphylobacter
- Borriella
- Leptospoira
- Treponema pallidium
What factors contribute to bacterial infections?
- Host factors - the immune system may be compromised by disease, age, therapies such as steroids to treat connective tissue disorder, cancer therapies that introduce neutropenia.
- Bacterial factors - these include virulence, resistance and environmental factors. Some bacteria like Staph. Aureus have virulence factors that allow them to adhere to tissues, damage them and avoid immune responses. Some organism are more adapt to surviving in the harsh environment - cold, floating in the air or on surfaces and resistant to disinfectant etc. This is seen particularly in the gram positive bacteria.
- Opportunity - exposure or when the source of infection is yourself.
What pathogen is carried in the nose of 50% of people and can adhere to damage skin?
Staphylococcus aureus. It can produce exoenzymes and toxins that damage tissues and provoke a host response. It is not a common cause of UTI but can cause an infection post surgically with catheters. It can lead to:
- Bacteraemia/septicaemia - Osteomyelitis/septic arthritis - (endocarditis, URI, Pneumonia, meningitis rarely)
Give details of Staphylococcus epidermidis.
S. epidermidis is an opportunistic skin commensal pathogen. It does not have the same capabilities of S. aureus in producing exoenzymes and toxins but it can adhere to plastics and metals using glycocalyx (slime) forming biofilms. It can therefore cause infection in association with foreign bodies. It can survive in a harsh environments as it resits drying.
What is the most common cause of bacterial sore throat?
Group A Streptococcus pyrogenes. It is the most significant species of Streptococcus in clinic.
The pathogen can also cause:
- Scarlet fever - Necrotising fasciitis - Other Skin and soft tissue infections - Invasive infections, such as pneumonia - Also associated with secondary immunological presentations, such as glomerulonephritis
What is the most common cause of bacterial pneumonia?
Streptococcus pneumoniae. It can also cause bacterial meningitis except in neonates. It can also cause common childhood infection such as otitis media - infection of the middle ear that causes inflammation and a build-up of fluid behind the eardrum.
What infection can Streptococcus agalactiae (Group B Streptococcus) lead to?
Commonest cause of bacteria meningitis and sepsis in neonates.
What infection can Streptococcus Miller complex colonisation lead to?
The pathogen forms apart of normal flora in the URT in the gingival cervices, GI tract and large bowel. It can therefore form abscesses. It is a pus-forming streptococci. It is now recognised as a significant pathogen associated with abdominal, thoracic and hepatic sepsis.
Give details of Viridans streptococci.
Collective name for a number of species of α-haemolytic streptococci that inhabit the upper respiratory tract e.g. S. oralis, S. mitis. They are commensal bacteria that can cause infection such as infective endocarditis, through bacteraemia.
Viridans streptococci, a diverse group of streptococcal species, are important causes of sepsis and pneumonia in the neutropenic host and sepsis and meningitis in the neonate. The oral mucosa is the most common portal of entry.
Give details of Listeria monocytogenes.
Infection is usually as a result of Zoonosis - it is able to grow at low temperatures. It is associated with consuming cheese made from unpasteurized milk and foodstuff. Infection is rare but it can cause meningitis in pregnancy, neonates and immunosuppressed patients.
