Concepts of Infection II Flashcards
What is the most common group of gram negatives that causes infection?
Enterobacterales = aerobic bacilli (e.g ecoli, salmonella, proteus)
What bacteria does the pseudomonas group encompass?
Aerobic gram negative bacilli that aren’t part of the coliform
What type of bacteria are neisseria?
Gram negative aerobic cocci
What component of the cell wall in gram negative bacteria drives sepsis in this group?
Lipopolysaccharide
What are some descriptors of sputum that would indicate particular organisms?
Rusty = pneumococcus
Bloody = TB
Yellow/green = bacterial infection
Redcurrant jelly = klebsiella
What are some descriptors of sputum that would indicate certain conditions?
Bloody = PE
Black = coal miners
Anchovy paste = ruptured amoebic abscess
Pink frothy = pulmonary oedema
What is the most common infection associated with HIV?
Strep pneumoniae = causes pneumonia
What is coxiella infection associated with?
Farm animals = produced when animals give birth
What is psittacosis associated with?
Birds of the parrot family
What is the typical cause of a middle lobar pneumonia?
Strep pneumoniae
How is atypical pneumonia treated?
Doxycycline covers most causes
Clarithromycin for legionella
How is an atypical pneumonia described?
Involvement of more than one lobe bilaterally
What are some causes of atypical pneumonia?
Mycoplasma pneumoniae, coxiella burnetti, chlamydiophila psittaci, legionella, viral or fungal
Following an influenza illness, what are the most common infections?
Strep pneumoniae, then staph aureus
What is haemphilus influenzae?
Gram negative coccobacillus = encapsulated or non-encapsulated
What is the most virulent form of haemophilus influenzae?
Type B encapsulated form
What are some features of haemophilus influenzae?
Generally aerobic
Grows on chocolate agar
Treated be amoxicillin or doxycycline
What type of bacteria is legionella pneumophila?
Gram negative bacilli = serogroup 1 causes most disease
How is legionella pneumophila diagnosed?
By performing broncho-alveolar lavage
What are the risk factors for legionella pneumophila?
Main association is lukewarm aerolised water
Risk factors = COPD, smokers, diabetes, dialysis
What other disease does legionella pneumophila produced, other than pneumonia?
Pontiac fever
How is legionella pneumophila treated?
Quinolones (e.g ciprofloxacin)
How is coxiella burnetti infection diagnosed?
By serology
What type of bacteria are enterobacterales?
Gram negative bacilli
What are some examples of fast-lactose forming gram negatives?
Ecoli, klebsiella, enterobacter
What organisms would be indicated if a culture grew non-lactose fermenting gram negative bacteria?
Pseudomonas
What gram positives cause anthrax?
Bacillus spp group
Where is lactobacillus found?
In gut and vagina = gram positive bacteria
What type of bacteria is corynebacterium?
Gram positive bacilli = found on skin
What are some antibiotics that will be effective against gram negative bacteria?
Beta lactams, aminoglycosides, macrolides, tetracyclines, chloramphenicol, co-trimoxazole, polymixins
What is the most commonly used antibiotic for gram negative infections and sepsis?
Gentamicin
What are some examples of beta lactams?
Penicillin, flucloxacillin, amoxicillin, cephalosporins, co-amoxiclav, meropenem
What method do aminoglycosides rely on to kill bacteria?
Concentration dependent killing
What type of bacteria are streptococci?
Gram positive cocci in pairs or chains = catalase positive and facultative anaerobes
What can a facultative anaerobe do?
Grow both aerobically and anaerobically
How can streptococci be classified using their action on agar?
Beta haemolytic = complete haemolysis (yellow)
Alpha haemolytic = partial haemolysis (brown)
Gamma haemolytic = no haemolysis
What type of haemolysis do Group A and B streptococci show?
Beta haemolysis
What are some examples of alpha haemolytic streptococci?
Strep pneumoniae and viridans
What can Group A streptococci also be called?
Strep pyogenes
What is strep bovis associated with?
Endocarditis and colonic tumours = now called strep gallolyticus, Belongs to Group D and is alpha haemolytic
What antibiotic is mostly used to treat streptococci?
Benzylpenicillin
When is Vancmycin used to treat streptococcal infection?
In penicillin-allergic patients and to treat meningitis caused by strep pneumoniae
What bacteria is vancomycin active against?
Only gram positive = works at cell wall, not active against gram negatives or anaerobes
What is the first line antibiotic used to treat enterococcus?
Amoxicillin
What antibiotics is enterococcus intrinsically resistant to?
Penicillin, flucloxacillin, cephalosporins and aminoglycosides
Where are enterococci found?
In the GI tract
What type of enterococcus causes the most disease?
E.faecalis
What are some side effects associated with linezolid?
Serotonin syndrome and marrow toxicity
What is the first line antibiotic for staph aureus sepsis?
Flucloxacillin
What type of bacteria is nocardia?
Gram positive bacilli = occurs in those with HIV or on immunosuppression
What type of bacteria is listeria?
Gram positive bacilli = seen in alcohol excess and pregnancy, associated with unpasteurised cheese
