microbes in blood Flashcards
is blood sterile
normal blood is sterile (no pathogens)
bloodstream infections caused by?
bacteria - s aureus
fungi - c. albicans
viruses - herpes simplex
name of blood stream infection caused by fungi?
fungaemia
name of blood stream infection caused by virus
viraemia
how does pathogens enter the bloodstream?
broken skin - cellulitis
mucous membranes - mucositis
dental abscess - collection of pus
GIT infections
viral reactivation - herpes zoster
direct inoculation - into vascular system, could be a cannula
what factors affect the mortality rate of a microbe bloodstream infection
the source
the type of microbe
host immune system
do bloodstream infections have high mortality rate?
yes
how long can microbes last in the blood?
- transient ie several minutes bacteraemia
- intermittent ie undrained abscess or infected biofilm
- continuous ie severe infection that has overwhelmed host defences eg IE
what can a bacteremia be caused by?
manipulation or surgical procedure involving infected tissues, TRANSIENT presence of bacteraemia
signs of IE
splinter hemorrhages
(microemboli in nailbed)
Roths Spots in retina
fever
tachycardia
2 most common microbes in blood stream infections?
- ECB = e coli bacteraemia
- SAB = s. aureus bacteraemia
3 most common reasons for e coli bacteraemia?
- lower urinary tract infection
- catheter associated urinary tract infection
- hepatobilliary infection
what % of all SAB cases are MRSA and MSSA? which one is “better” in terms of treatment?
MSSA = 97%
MRSA = 3%
better that most are MSSA because can use flucloxacillin.
vancomycin is used for MRSA, harder to administer, only can IV
antibiotic for MRSA
VANCOMYCIN
antibiotic for MSSA
flucloxicillin
fatality rate for ECB
14%
fatality rate for SAB
40 for SAB IE
3 most common reasons for SAB?
skin and soft tissue infections
vascular access devices
unable to determine by team
what bacteremia do we worry about in pregnant women?
listeria monocytogenes
what bacteremia do we worry about in neonates?
group B strept
e coli
what bacteremia do we worry about in children?
pneumococci
group A strept
meningococci
group A strept aka?
Strept. pyogenes
what bacteremia do we worry about in immunocompromised patients?
gram negative
- e coli
- pseudomonas aeruginosa
both associated with severe sepsis and high mortality rate
what is the wcc level to be classed as immunocompromised?
wcc less than 0.5 x 10^9 /L
how do we detect bacteraemia in blood? prob dont need to know much about this
BAcTec
molecular methods
why is molecular methods better than BacTech system?
1h turn around time compared to 48h for BacTec
this is a great improvement for patients
what is IE?
infection of the heart valves or other areas of the endocardium
what other diseases could predispose you to have IE
congenital heart disease
rhematic valvular disease
mitral valve prolapse with murmur
degenerative heart disease
what species causes IE
70% steptococcal
25% staphylococcal - more aggressive
there is no such thing as streptococcus viridans. there are 8 groups of streptococci. which causes IE?
all can cause IE. most common is streptococcus mitis.
which bacteria falls under Lancefield group D and why is it important?
Enterococcus bacteria. (which is a species under S. pyogenic)
it causes IE
is streptococci only found in the oral cavity?
no, it can be found in the oral cavity, GIT, hepatobilliary system etc
can u find staphylococcus aureus in the oral cavity?
yes
name a species of s.aureus in oral cavity
staphylococcus epidermis
name the bacteria that causes recurrent endodontic infections
Coagulase negative staphylococci can colonise and infect the oral cavity , causing recurrent endo infections
what are some characteristics of native valve endocarditis in sub type intravenous drug users?
- younger age group
- s.aureus more predominant
- mostly affects right side heart valves
- lead to multiple lung abscesses
types of IE
NVE native valve endocarditis
PVE prosthetic valve endocarditis
bacteria in NVE
s. aureus
bacteria in PVE
coagulase negative staphylococci (CNS)
S.aureus
Gram negative bacilli
is antibiotic prophylaxis successful and effective for preventing IE?
little evidence,
AB for dental tx in patients at risk of IE is NOT routinely recommended except for 3 special groups
possible reason for increase in IE?
restriction in Antibiotic prophylaxis?
not all microbes causing IE are susceptible to amoxicillin that is prescribed
is it acceptable to prescribe Antibiotic prophylaxis for a patient with prosthetic joint?
no
just maintain good OH
