Gram Pos Flashcards
How to differentiate Gram negative and positive?
Gram pos - purple stain
Gram neg - pink stain
How to differentiate staphylococcus from streptococcus?
Staph - clusters, catalase positive
Strep - chains, catalase negative
How to differentiate s. aureus from other staph?
Staph - coagulase positive
What is the most common causes of SSTIs
S. Aureus w wound and S. Pyogenes without wound
What infections do s. aureus cause
Boils
Impetigo
Septic arthritis
Cellulitis
Osteomyelitis
Pneumonia
Endocarditis
What are the exotoxins released by S.aureus
TSST-1
Epidermolytic toxins A&B
Preformed enterotoxins A-E
What does TSST-1 cause?
TSS
What do Epidermolytic toxins A&B cause?
Scalded skin syndrome
What do Preformed enterotoxins A-E cause?
Food poisoning
What to do when patient suffers from CNS catheter related bacteraemia?
Treat with antibiotics as the infection is less severe than s.aureus and removing and replacing of the line can cause trauma for the patient
What to do when patient suffers from s.aureus catheter related bacteraemia?
Remove the line
Treat with appropriate antibiotics
How to treat MRSA
Vancomycin
How to treat MSSA
Penicillin (Cloxacillin)
Erythromycin if penicillin allergy
What infections are strep pyogenes the common cause of?
Pharyngitis
Impetigo
Cellulitis
How to treat VRSA and VRE
Linezolid
What are the toxin mediated infections due to S. pyogenes?
TSS
Scarlet fever
Necrotising fasciitis
What causes scarlet fever?
Erythrogenic toxins from pharyngitis S.pyogenes.
How do you treat necrotising fasciitis?
Debridement
IV Benzylpenicillin, IVIg and Clindamycin
What are the immune-mediated post infection sequelae caused by S.pyogenes?
Acute Rheumatic Fever
Acute Glomerulonepheritis
How does rheumatic fever come about?
M protein of S. pyogenes molecular mimicry of myosin
Causes antibodies to cross-react with self antigens and attack the heart
How do you diagnose immune mediated post-infection sequelae caused by S. pyogenes?
Anti-streptolysin O titre
How do you diagnose acute rheumatic fever?
JONES criteria
Joints
Carditis
Nodules
Erythema marginatum
Sydenham chorea
Where is S. aureus found?
Anterior nares 30%
What infections are s.pneumoniae the common cause of?
Meningitis
Otitis media
Pneumonia
Sinusitis
Antibiotics for common strep infections?
Penicillins or amoxicillins
How do you treat meningitis due to S. pneumoniae?
Ceftriaxone and vancomycin
How to diagnose S.pneumoniae?
Meningitis - CSF culture
Pneumonia - sputum culture
General - Blood culture or urine antigen detection
What are some risk factors of S. pneumoniae?
Age
Crowding
Alcohol
Capsule types
Asplenic
PPSV23 should be used for what age group?
Elderly
PCV10/13 should be used for which age group?
Babies
Where is S. Agalactiae found?
Normal flora of GIT
Vaginal in 30% of women 30% of the time
What does S. agalactiae cause in adults? What increases the risk of contracting it?
Meningitis, Arthritis and Sepsis
Raw freshwater fish and co-morbidities
What does S. agalactiae cause in babies and how do you prevent it?
Neonatal sepsis
Prophylactic penicillin given to mother before birth
What are the infections caused by S. bovis?
Hepatobillary infections
Bovis in the blood causes colon cancer
Endocartitis
What are enterococcus associated with?
UTI and billary infections (nosocomial)
What are viridian associated with?
Dental procedures
What are viridians the most common cause of?
Subacute endocarditis of heart valves with previous damage
List aerobic gram pos rods
Corynebacterium Diphtheriae
Listeria Monocytogenes
Bacillus cereus
Bacillus anthracis
What does Corynebacterium Diphtheriae cause and what are the clinical presentations?
Diphtheria
Bull neck and greyish white pseudomembrane on tonsils
How is diphtheria treated and prevented?
Antitoxin and Penicillin
Prevented with toxoid vax
Where is Listeria Monocytogenes found?
Salad leaves, soft cheese and deli meats
What does Listeria Monocytogenes cause and what is the treatment?
Gastroenteritis and meningitis in immunocompromised
Ampicillin
List anaerobic gram pos rods
Clostridium Botunilum
Clostridium Tetani
Clostridium Perfringens
Clostridium Difficile
What is bacillus cereus associated with and what does it cause?
Fried rice food poisoning
Fast onset vomitting
Slow onset diarrhoea
What does bacillus anthracis cause and what are the clinical presentations?
Anthrax which can become pulmonary anthrax
Black lesions
What does C. botulinum cause?
Blocks ACh release => flaccid paralysis
Drooping eyelids/ floppy baby syndrome
What does C. Tetani cause
Blocks inhibitory neurotransmitter release @LMN => spastic paralysis
What does C. perrfringens cause and how to treat it?
Gas gangrene due to alpha toxin
Debridement, IV benzylpenicillin, clindamycin
What does C.difficile cause and how to treat it?
CDAD due to antibiotic administration which reduces competitive normal flora
Stop antibiotics, oral vancomycin
What is the most common cause of necrotising fasciitis?
- S.pyogenes
- S.aureus
What organism causes wet gangrene diabetic foot ulcer?
Anaerobes
What is the most common cause of pharyngitis?
Viral and s.pyogenes (33%)
Which organisms are the top culprits of meningitis?
S. pneumoniae and N. meningitidis
How do you treat strep throat?
Oral penicillin v
What organisms are the most common cause of otitis media?
- S.pyogenes
- H. influenzae
What is the number 1 cause of pneumonia?
S. Pneumoniae
What organisms are the likely culprits of nosocomial pneumonia?
S. aureus
Legionella
PAE
What is the common cause of diarrhoea in children?
Rotovirus
What is the common cause of vomitting not associated with anything?
Norovirus
What is the common cause of seafood related diarrhoea?
V. parahaemolyticus
What are the organisms that normally cause conjunctivitis?
Adenovirus, S. pneumoniae and H.influenzae
What organisms show draughtsman colonies?
S. pneumoniae
