Systemic infections Flashcards
37 year old with fever, and leukocytosis. Had non-itching pink rash on arms/ torso, particularly when had fever.
Given co-amoxiclav with no improvement, then given tazocin.
CXR - bilateral pulmonary infiltrates
CRP 268
Ferritin >40 000
Raised ALT
CT CAP - nil obvious found
What criteria does patient meet to be diagnosed with PUO?
- Temp >38.3 on 3x occasions, over 3 weeks
- Includes a week of routine hospital based investigation, without diagnosis being reached
Can also be classified by patient group -
- HIV patient
- transplant patient
- returning traveller
- nosocomial onset
37 year old with fever, and leukocytosis. Had non-itching pink rash on arms/ torso, particularly when had fever. Arthralgia
Given co-amoxiclav with no improvement, then given tazocin.
CXR - bilateral pulmonary infiltrates
CRP 268
Ferritin >40 000
Raised ALT
CT CAP - nil obvious found
What is possible diagnosis?
What is significance or extremely high ferritin?
Adult onset Stills disease (AOSD)
fever, arthralgia, leukocytosis, hepatitis may indicate this
high ferritin suggestive of haemophagocytosis, which can occur in Still disease, and HLH (haemophagocytic lymphohistiocytosis)
treatment is NSAIDs/ steroids
What are causes of PUO?
Infection - 1/3 of cases. This is more likely if from poorer country. Developed country patients are less likely to have chronic bacterial infections
auto-immune
malignancy
vasculitis
42 year old with tunneled dual lumen vascular haemodialysis catheter has fever while on dialysis.
4x blood culture bottles grow staph epidermidis, susceptible to vancomycin
Should line be removed?
No
coagulase negative staph are unlikely to form biofilms, so catheter salvage can be attempted
if pseudomonas/ candida - line needs removed
If no evidence of infection of skin, then infection is likely intraluminal. And therefore more likely to point to biofilm producing organism
42 year old with tunneled dual lumen vascular haemodialysis catheter has fever while on dialysis.
4x blood culture bottles grow staph epidermidis, susceptible to vancomycin
How should they be managed?
Give vancomycin, as can be given on dialysis
2 weeks antibiotics for CoNS
consider using line lock e.g vancomycin, ethanol for 2 weeks.
42 year old with tunneled dual lumen vascular haemodialysis catheter has fever while on dialysis.
4x blood culture bottles grow staph epidermidis, susceptible to vancomycin.
Treated with vancomycin.
1 month later has fever, erythema and tenderness around line site.
Blood culture grow MRSA
What is further management?
Start treatment for MRSA - vancomycin for 14 days
blood cultures 48 hours on treatment - to ensure no persisting bacteraemia. As this may suggest complicated/ metastatic infection
examine for back/ joint pain, IE
may need ECHO if not a simple infection - e.g not responding to antibiotics
Patient has hemicolectomy, and goes on ventilator after this.
Jugular vein used for TPN.
Develops fever
Paired peripheral and central blood cultures flag positive at 12 hours.
Identified as candida albicans in central/ peripheral cultures. staph epidermidis only peripheral cultures
What is significance of these isolates?
candida is unlikely to be contaminant - forms biofilms
S epidermidis likely contaminant as just peripheral cultures
What us management of catheter related candidaemia?
What is duration of treatment?
- C. albicans is normally susceptible to azoles, echinocandins, and amphotericin B
- fluconazole favoured due to good tolerability
800mg loading dose, followed by 400mg daily - C glabrata, C krusei are increasing in prevalence, and show reduced susceptibility to azoles.
- Follow up blood cultures required to assess if clearing candidaemia
- Normally 14 days treatment
- refer for ECHO/ ophthalmology to ensure not seeded infection
What is criteria of culture negative endocarditis?
3 blood cultures negative after 5 days
when suspecting IE, what questions in history help point towards possible aetiological agent?
unpasteurised cheese/ milk, undercooked meat, or travel to Middle East/ Mediterranean - Brucella
Occupational exposure e.g farms/ abattoir - coxiella
Contact with human louse/ homeless/ alcoholism - Bartonella quintana
Cat scratch - Bartonella henselae
Also useful - cardiac device intravascular lines HIV history of previous antimicrobials
Can endocarditis be non-infective in origin?
Non-bacterial thrombotic endocarditis (NBTE) is form of endocarditis where small sterile vegetations deposited on valve leaflets
associated with connective tissue disease e.g rheumatic fever, SLE
NBTE associated with SLE is also known as Libman-Sacks endocarditis
How to optimize blood cultures growth?
Incubate within 4 hours of taking
Take 3 sets - yield increases from 61% from 1 set, to 93% yield in 3 sets
Patient with ruptured appendix, then deteriorates.
Fever, hypotension.
Not responding to cefotaxime/ metro
Gram neg bacilli seen on culture
Why might patient not be responding to antibiotics?
Gram negative bacilli likely E. coli/ klebsiella
cefotaxime can be inactivated by ESBL
source of infection not controlled - collection
What are the most common ESBL enzymes?
TEM - 50% of ESBL
SHV
CTX-M
Patient with ruptured appendix, then deteriorates.
Fever, hypotension.
Not responding to cefotaxime/ metro
Gram neg bacilli seen on culture
Thought to be CPE
How to reduce spread of CPE in hospital?
Early recognition
patient isolation - for duration of hospital admission
contact precautions/ hygiene
weekly rectal swabs
no methods of decolonisation available
What drugs are available to treat CPE infections?
Colistin
aminoglycosides
tigecycline
fosfomycin - can be used IV
newer agents showing promise - ceftazidime-avibactam, aztreonam-avibactam, eravacycline
What are CPEs?
Bacteria which produce enzymes which hydrolyse all beta-lactam molecules, including carbapenems
How to identify CPE in laboratory?
Disk diffusion may show resistance to ertapenem
MALDI-TOF may show genotypic likely to be resistance
How long can incubation period of Plasmodium falciparum be?
Can be up to 12 months since exposure
What are features of severe malaria?
Biochemical
Biochemical - AKI pH <7.3 Glucose <2.2 Hb <8 Parasitaemia >10%
Thrombocytopenia is always seen in malaria, but does not necessarily indicate severe disease
