Bacterial Pathogens Flashcards
Staphylococcus Aureus
Gram Positive Primary Pathogen. 30-50% of the population carry it nasally. Commonest cause of skin/soft tissue infection. Can Cause: Bacteraemia/Septicaemia Osteomyelitis/Septic Arthritis Endocarditis Pneumonia UTI Meningitis
Staphylococcus Epidermidis
Gram Positive
Opportunistic Pathogen
Skin commensal
Coagulase negative staphylococci
Infection is associated with foreign bodies.
Adheres to plastics/metals using glycocalyx (slime).
Streptococcus Pyogenes
Gram Positive Group A Strep. Commonest cause of bacterial sore throat. Associated with secondary immunological presentations (i.e. glomerulonephritis). Can Cause: Scarlet Fever Necrotising Fasciitis Pneumonia Puerperal Sepsis
Streptococcus Pneumoniae
Gram Positive
Commonest cause of bacterial pneumonia and meningitis (not including neonates - babies under 3 months of age).
Can Cause:
Otitis Media - middle ear infection
Streptococcus Agalactiae
Gram Positive
Group B Strep.
Cause of bacterial meningitis in neonates.
Streptococcus Milleri Complex
Gram Positive
Pus forming
Associated with abscesses - i.e. dental, lung, liver and brain
Viridans Streptococci
Gram Positive
Collective name for a number of alpha haemolytic strep.
Inhabits the URT i.e. S. oralis & S. mitis
Can Cause:
Sub-acute bacterial endocarditis.
Streptococcus Gallolyticus/Bovis
Gram Positive
Alpha haemolytic strep that forms bowel flora.
Can Cause:
Bacteraemia associated with CRC.
Listeria Monocytogenes
Gram Positive Zoonosis Able to grow at low temperatures Associated with consumption of cheese made from unpasteurised milk Can Cause: Sepsis Meningitis
Corynebacterium
Gram Positive
Opportunistic infections associated with devices and trauma.
A number of species are commensals of skin and URT.
Corynebacterium diphtheriae - classic cause of diptheria.
Propionibacterium Acnes
Gram Positive
Associated with acne.
Enterobacteriaceae (coliforms)
Gram Negative Collective name for a number of GN bacilli found in bowel flora. E. Coli Klebsiella Pneumoniae Enterobacter Cloacae
Escherica Coli
Gram Negative
Commonest cause of UTI and bacteraemia.
Toxic Strains (0157) associated with severe diarrhoea and haemolytic uraemic syndrome (HUS).
Can Cause:
Nosocomial infections (hospital acquired) - line infections, pneumonia, wound infections.
Pseudomonas Aeruginosa
Gram Negative Multi-resistant Opportunistic Characteristic for 'blue-green pus' (if asked in an exam, say green). Can Cause: Respiratory infections UTIs Soft tissue infections
Neisseria Meningitidis
Gram Negative Diplococcus Note 'glass test' for a purpuric non-blanching rash. Can Cause: Meningococcal Sepsis Meningitis
Neisseria Gonorrhoea
Gram Negative
Diplococcus
Rarely an invasive infection.
STI - gonorrhoea - leads to opthalmia neonatorum.
Haemophillus Influenzae
Gram Negative Normal respiratory tract flora. Capsulated types (type B) are associated with Meningitis and Epiglottitis. Type B infections prevented by HIb vaccine. Can Cause: Respiratory infections Pneumonia Infective exacerbations of COPD
Anaerobes
Clostridium - Gram Positive, Spore Forming
Bacteroids - Gram Negative
Fusobacterium - Gram Negative
Prevotella - Gram Negative
Tend to be part of polybacterial infections - dental infections, lung abscesses etc.
Clostridium
Gram Positive Spore Forming C. dificile - Abx associated diarrhoea and collitis C. perfringens - Cause of gas gangrene C. tetani - Cause of tetanus C. botulinum - Cause of botulism
Mycobacterium Species
Acid Fast Bacilli (AFB) - does not stain using conventional gram staining.
Mycobacterium Tuberculosis - cause of TB.
Other Mycobacterium species are referred to as “Atypical Mycobacteria”
Atypical Mycobacteria can cause:
Respiratory infections in chronic respiratory patients.
Opportunistic infections in immuno-compromised patients.
Spirochaetes
Gram Negative
Treponema Pallidum - Syphilis
Leptospirosis - Spread by animals
Lyme Disease - Spread by infected tics
Bacteria without a cell wall
Gram Negative Chlamydia Species C. trachomatis - commonest cause of STI Mycoplasma Species M. pneumoniae - common cause of respiratory tract infections.
Gram Positive Bacterial Pathogens and brief explanation…
Staphylococcus Aureus
Staphylococcus Epidermidis - foreign bodies
Streptococcus Pyogenes - commonest bacterial sore throat
Streptococcus Pneumoniae - commonest bacterial pneumonia and meningitis excluding neonates
Streptococcus Agalactiae - commonest bacterial meningitis in neonates
Streptococcus Milleri complex - pus forming/abscess causing
Viridans Streptococci - group of alpha haemolytic strep, sub-acute endocarditis
Streptococcus Gallolyticus/Bovis - alpha haemolytic strep. Bacteraemia CRC
Listeria Monocytogenes - consumption of unpasteurised milk.
Corynebacterium - classic cause of diptheria
Propionibacterium Acnes - associated with acne
Gram Negative Bacterial Pathogens and brief explanation…
Enterobacteriacaea - bowel flora
E.Coli - commonest cause of UTI
Pseudomonas Aeruginosa - multiresistant green…
Neisseria Meningitidis - diplococcal meningococcal sepsis/meningitis
Neisseria Gonorrhoea - diplococcal… gonorrhoea
Haemophillus Influenzae - capsulated type B prevented by H1b vaccine
Bacteroid, Fusobacterium, Prevotella - anaerobic
Chlamydia species - lacks a cell wall
Mycoplasma species - lacks a cell wall, commonest cause of respiratory tract infections (M. pneumoniae)
Spirochaetes - siphilis and lyme disease
Causes of Meningitis
Staphylococcus Aureus Streptococcus Pneumoniae Streptococcus Agalactiae Listeria Monocytogenes Neisseria Meningitidis Haemophillus Influenzae type B
