Microbiology Flashcards
Gram staining results?
Gram +ve = purple
Gram -ve = pink
What are the two main types of coccus bacteria and how do they appear?
Strep = chain Staph = clusters
How can you differentiate between Staph bacterium (will be GRAM +VE)
Coagulase test
Positive = S. aureus
Negative = S. epidermidis or S. saprophiticus
How can you differentiate between Step bacterium (will be GRAM +VE)
Grow on blood agar
Alpha-haemolytic = dark green - S.pneumoniae, S. pralis, S.sanguis
Beta-haemolytic = pale yellow/transpartent - S.pyogenes (group A), S.agalactiae (group B)
Non-haemolytic = no change - S. mutans, S. milleri or eneterococcus faecalis
What is the main gram positive bacilli? Is it aerobic or anaerobic?
Clostridium difficile (all clostridiums are anaerobic)
What are the two main coccus gram negative bacteria?
N. meningitidis, N. gonorrhoea
How do you differentiate between gram negative bacilli?
MacConkey plate
Lactose fermenters = pink - E.coli, K. pneumoniae
Non-lactose fermenters = pale - salmonella, shigella and proteus
What test can differentiate between Staph and Strep bacteria?
Catalase test
Staph = produce gas bubbles
Strep = no bubbles
What are the two actions of antibiotics?
Bacteriocidal = kill bacteria Bacteriostatic = stop bacterial growth to allow the body to destroy the bacteria
Which antibiotics inhibit cell wall synthesis?
Beta-lactams (penicillins, cephalosporins and carbapenems), vancomycin
Which antibiotics inhibit neucleotide synthesis?
Trimethoprim, Metronidazole and Rifampicin
Which antibiotics inhibit protein synthesis?
Clarithromycinm gentamicin and tetracyclines
Which antibiotic treats specifically staph. aureus?
Flucloxacillin
Which antibiotic is commonly used to treat MRSA?
Vancomycin
What is the main causative organism in infective endocarditis and what is the AB treatment?
Step. viridans
4-6 weeks of IV benzylpenicillin +/- 2 weeks gentamicin
What is the most common cause of CAP and what is the AB treatment?
Strep. pneumonia - depends on CURB65 score
0-1 = amoxicillin
2 = amoxicillin and clarithromycin
3+ = IV co-amoxiclav and clarithromycin
What is the most common cause of HAP and what is teh AB treatment?
Saph. aureus/MRSA - IV gentamicin and a penicillin
What are the three main TB symptoms?
Night sweats, productive/sputum cough and weight loss
How do you test and AB treat TB
Test: Ziehl-Neelsen stain = active disease, Mantoux skin test = latent disease
Treatment = Rifampicin, Isoniazib, Pyrazinamide, Ethambutol (RIPE)
What are the main causative organisms of SBP and what is the AB treatment?
E.coli, Klebsiella and Strep. pneumoniae (kids)
IV cefotaxime and metronidazole
What is the AB treatment for appendicitis?
IV cefotaxime and metronidazole
What are teh main causes of UTI and what is the AB treatment?
E.coli (70%), proteus miribilus and klebsiella
Trimethoprim or Nitrofurantoin if in 1st trimester of pregnancy
What are the signs of sepsis?
Shivering/fever, Extreme pain, Pale skin, Sleepy/confused, Impending doom, SoB (SEPSIS)
How do you treat HIV and when does it become AIDS?
HAART anti-retrovirals to treat HIV
Becomes AIDS when CD4 < 200 cells/ml and/or there is an AIDS defining illness present
AB treatment for septic arthritis?
IV flucloxacillin and double steroids for 6 weeks
What cuases osteomyelitis?
Staph. aureus, strep or enterococci in the immunosuppressed/diabetics post-joint surgery
How do you treat the two main causes of reactive arthritis?
Chlamydia = docycyline (7 days) or 1 dose azithromycin
N. gonnorrhoea = ceftriaxone IM PLUS 1 dose axzithromycin
What are the most common causes of meningitis?
EBV, herpes simplex virus and mumps - VIRAL = MOST COMMON
Bacterial: Strep. pneumoniae (most common), N. meningitidis (most severe), H. influenzae
What is the AB treatment of meningitis in the community/hospital?
Community = IM benzypenicillin
Hospital: <55 = IV cefotaxime,
>55, immunocompromised or pregnant IV cefotaxime AND amoxycillin
How do you treat close contacts in a meningitis case?
Give them rifampicin and Meningitis C vaccine
What is the most severe cause of encephalitis and what is the AB treatmnet?
Herpes Simplex Virus
IV acyclovir
What causes shingles and what is the AB treatment?
VZV - Acyclovir
What are the most common causes of cellulitis and what is the AB treatment?
Staph aureus and strep - IV flucloxacillin and benzylpenicillin
What are the cuases of malaria, how is it carried and how is it treated?
P. falciparum (main), P. malariae, P. vivax, P. ovalae
Anopheles mosquitoe (female)
Treat with quinine
