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 render medications used to cure infection they cause ineffective
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.
- viridans group streptococci eg S. mitis
- 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)
- Often anaerobes including P. intermedia, P. gingivalis, A. israelii
- anaerobes: S. anginosus
how to manage dental abscess
-if localised infection
- take hisotry
- establish diagnosis and document
- remove source of infection
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
common bacteria found in dentoalveolar abscess, give example of antibiotic against them
- streptococci : streptococcus anginosus
Penicillin (cell wall)
Clindamycin (protein synthesis) - strict anaerobes: Prevotella intermedia
Penicillin (cell wall)
Metronidazole ( DNA synthesis)
What bacteria are involved in pericoronitis?
- predominantly 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
What is the management of salivary gland infection?
6 weeks IV antibiotics
What is the management of pericoronitis?
- local measures
- metronidazole if signs of spreading infection
what you must do in antibiotic presciption
- document diagnosis
- document Ab choice, dose, route, duration
- document review date
- document deviation from guidance
what guidance to follow for Ab presciption
SDCEP
durg presciption for dentistry
BNF
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. intermeida/ P. gingivalis)
- S. anginosus
What is SIRS?
Systemic inflammatory response syndrome
2 or more of the following criteria
- temp <36 / 38C
- Pulse > 90/min
- Resp rate > 20/min
- WCC <4 or >12
What is sepsis?
Life threatening organ dysfunction caused by dysregulated host response to infection
sepsis = SIRS + suspected/ confirmed 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.
A coherent set of actions which promotes using antimicrobials resposibly
- infection prevention
- decreasing prescriptions
When do you prescribe Metronidazole
- strictly anaerobic
- Periodontal infections
- when allergic to penicillin
what is first line therapy in antibiotics
- Penicillin V (Phenoxymethylpenicllin)
pen v vs amoxicillin
- amoxicillin has a broader spectrum of activity than Pen V
- greater impact on selection of resistance in the host micro-flora
dental abscess - phenoxymethylpenicillin presciption dose
- 500mg
- 5 days
- 4 times daily
can cause hypersensitivity and anaphylaxis
dental abscess - amoxicillin presciption dose
- 500mg
- 5 days
- 3 times daily
can cause hypersensitivity and anaphylaxis
dental abscess - metronidazole presciption dose
- 400mg
- 5 days
- 3 times a day
