3 - Microbiology and antimicrobials Flashcards
Give an example of a gram positive cocci.
S. anginosus
Give an example of a gram negative cocci.
Veillonella species
Give an example of a gram positive bacilli.
Actinomyces israelii
Give an example of a gram negative bacilli.
Prevotella intermedia
What is antimicrobial resistance?
When micro-organisms change in ways that prevent medications from working
What are the different types of resistance?
- intrinsic resistance
- acquired resistance
What is intrinsic resistance?
Resistance through structure or metabolic pathway
What is acquired resistance?
- mutation
- acquisition of new DNA
What are the different mechanisms of antibiotic resistance?
- altered target site
- enzymatic inactivation
- decreased uptake
Give an example of a microorganism that uses altered target site for antimicrobial resistance.
Penicillin resistance
Give an example of a microorganism that uses enzymatic inactivation for antimicrobial resistance.
- prevotella
- fusobacterium
- both use beta-lactamase enzyme
What is the beta-lactamase resistance arms race?
- penicillin resistant bacteria produced penicillinase to destroy the antibiotic
- chemists produced a new penicillin resistant to penicillinase with a beta-lactam ring
- bacteria produced beta-lactamase
- chemists produced extended spectrum antibiotics
- bacteria produced extended spectrum beta-lactamase
- this reduces antibiotic choice for infection
How do you treat a ESBL infection?
Carbapenems
What are CPEs?
Carbapenemase producing enterobacterales
What is MDRI?
Multi drug resistant infection
Describe a dental abscess infection.
- endogenous infection (often mixed)
- strict anaerobes including S. anginosus and P. intermedia
What is the ideal specimen of a dental abscess?
- pus aspirate
- as oxygen is toxic to many of the bacteria involved
What bacteria are involved in a periodontal abscess?
- anaerobic streptococci
- p. intermedia
What bacteria are involved in pericoronitis?
- mixed oral anaerobes (p. intermedia)
- s. anginosus
What bacteria are involved in dry socket?
Mixed oral flora
What bacteria are involved in osteomyelitis?
- anaerobic gram negative rods
- anaerobic streptococci
- s. anginosus
- s. aureus
What bacteria are involved in salivary gland infection?
- s. aureus
- mixed anaerobes
What is the management of salivary gland infection?
- drainage
- flucloxacillin
- metronidazole
- if severe, 6 weeks IV antibiotics
What is the management of pericoronitis?
- local measures
- metronidazole if signs of spreading infection
What is SOI?
- severe odontogenic infection
- spread of infection into tissue planes with systemic symptoms and signs of sepsis
What bacteria are involved in Ludwig’s angina?
- anaerobic gram negative bacilii (p.intermedia)
- s. anginosus
- anaerobic streptococci
What is SIRS?
Systemic inflammatory response syndrome
What is sepsis?
Life threatening organ dysfunction caused by dysregulated host response to infection
What does S mean in a microbiology report?
Susceptible at standard dose
What does I mean in a microbiology report?
Susceptible at increased dose
What does R mean in a microbiology report?
Resistant even with increased dose
Define a breakpoint.
Chosen concentration of an antibiotic which defines whether a bacteria is susceptible or resistant to the antibiotic
Define clinical resistance.
When an infection is highly unlikely to reposed even to maximum doses of antibiotic
Define antimicrobial stewardship.
Organisational or healthcare system wide approach to promoting and monitoring use of antimicrobials to preserve their future effectiveness
