Infectious Diseases Flashcards
What is staphylococcus aureus bacteraemia?
MRSA or MSSA
You should consider changing a peripheral venous catheter (line) if it has been in situ for over ___ hours?
Over 72 hours
When looking at blood culture bottles, the bottom ‘sediment’ should be what colour? Greenish or Orange
Greenish
What is important to remember when filling blood culture bottles?
Make sure the bottles are kept upright
What should you take first - blood cultures or blood samples?
Blood cultures
- taking blood samples first would increase the risk of contamination
Blood cultures should aim to be taken before/after initiation of antibiotic therapy?
Before antibiotics are administered
If patient has started antibiotics before blood cultures are taken, when is the best time to take blood cultures?
Immediately before the next dose of antibiotics is due
Which class of antibiotics are used to treat atypical pneumonias?
Macrolides (clarithromycin, azithromycin, erythromycin)
Bronchiolitis is most commonly due to which virus?
RSV
Which investigation is done to look for virus?
PCR
- nasopharyngeal swab
- throat swab
Blood cultures should ideally be taken at different times. True or false?
True
What is the name of the criteria used for endocarditis?
Duke criteria
Blood cultures are taken for suspected infective endocarditis but all 3 blood cultures have come back -ve. What is the next investigation?
Serology
- for atypical organisms
If there is a clinical suspicion of endocarditis, which imaging investigation should be carried out?
Transthoracic echo
Which type of echo should be done initially: transthoracic or trans oesophageal?
Trans oesophageal
Patient with red eye, gritty sensation, lots of pus and sticky discharge. Started unilaterally and now spread bilaterally. Vision is unaffected. What is the likely condition?
Bacterial conjunctivitis
What is the treatment of bacterial conjunctivitis
Self limiting
- chloramphenicol drops make infection clear up faster
Patient with bacterial conjunctivitis but the causative organism is pseudomonas aerginosa. What is the management>
Gentamicin
Chronic unilateral follicular conjunctivitis is a buzzword for which type?
Chlamydial conjunctivitis
Patient with watery eyes that are pink. There is a red velvety appearance of the conjunctiva. What is the likely diagnosis?
Viral conjunctivitis
Patient presents with a painful eye which is red around the limbus. There is reduced vision and a white lump is visible in the cornea. what is the likely diagnosis?
Bacterial keratitis
Investigation for bacterial keratitis
Corneal scrape
Management of bacterial keratitis
Hourly drops of ofloxacin (must be admitted to hospital)
What is a dendritic ulcer associated with (condition)
Viral keratitis
Patient presents with painful eye which is red around the limbus and also complains of reduced vision. There is profuse lacrimation. On examination, there is a thin white appearance in the cornea which looks like branches of a tree. what is the most likely diagnosis?
Viral keratitis (dendritic ulcer)
Management of dendritic ulcer
Antiviral (aciclovir)
Which medication causes a geographical ulcer in a patient with viral keratitis
Steroids
- avoid this
Patient presents with an extremely red and painful eye post surgery. What is the likely diagnosis?
Endophthalmitis
Main cause of orbital cellulitis in children?
Sinusitis
Child with pain and redness around the orbit. Also has a swollen tender eyelid and mucous dripping out of their nose. What is the likely diagnosis and how should it be investigated
Diagnosis: orbital cellulitis
Investigation: CT
What is the important investigation to carry out for orbital cellulitis
CT scan
Bilateral conjunctivitis in young adults. What should you suspect?
Chlamydial conjunctivits
What is the most common causative organism for endophthalmitis?
staph epidermidis
investigation for endophthalmitis
Aqueous / vitreous for culture
Chloramphenicol is bacteriocidal / bacteriostatic for staph?
Bacteriostatic
Chloramphenicol is bacteriocidal / bacteriostatic for strep?
Bacteriocidal
Side effect of chloramphenicol
Aplastic anaemia
What class of antibiotic is ofloxacin
Quinolone
Which specific bacteria does chloramphenicol not treat
Pseudomonas aerginosa
Hand foot and mouth disease is caused by which virus?
Coxsackie virus
Which patients with sore throats definitely SHOULD NOT receive a throat swab?
Patient with stridor
What is the most common cause of a bacterial sore throat
Tonsilitis
- group A strep (strep pyogenes)
Strep pyogenes (group A strep)
gram +ve or gram -ve
Cocci or bacilli
haemolysis: complete, partial or none
Gram +ve
Cocci
Complete haemolysis
Why should you be careful with carbimazole
It can cause neutropenia
Name 3 things which can cause neutropenia
Carbimazole
Chemotherapy
HIV with low CD4 count
Infectious mononucleosis (glandular fever) is caused by which virus?
EBV
What is the management of infectious mononucleosis?
Selt limiting
- steroids if very severe
Investigations for infectious mononucleosis
EBV IgM
monospot test
paul bunnell test
CMV and infectious mononucleosis present similarly. What is the difference to differentiate them by investigation
In CMV
- negative monospot test
- negative paul bunnell test
- fewer atypical lymphocytes
Name 3 causes of candida in the mouth
post antibiotics
immunosuppressed
inhaled steroids
Management of candida
Fluconazole
You should swab pus in acute ottitis media. True or false?
False
- only do this if the eardrum has perforated
Management of ottitis media
In first 4 days - self limiting
If over 4 days
- first line: amoxicillin
- second line: erythromycin
What is usually the causative organism of malignant ottitis?
Pseudomonas aerginosa
What is malignant ottitis?
Extension of otitis externa into the nearby bones (temporal, mastoid) and causes osteomyelitis
Name 3 bacterial causes of ottitis externa
Staph aureus
Proteus
Pseudomonas aerginosa
You should use topical / oral antibiotics for treatment of ottitis media?
Topical
Persisting sinusitis infection over 10 days. Which antibiotic is used to treat?
Phenoxymethylpenicillin
Which criteria is used for differentiating viral vs bacterial tonsilitis
centor criteria
What is the management of bacterial tonsilitis
Penicillin
Bacterial meningitis - which types of cells will be present
Abundant neutrophils
Which antibiotic is used in bacterial meningitis
2b IV ceftriaxone BD
Management of bacterial meningitis
IV ceftriaxone 2g IV BD
IV dexamethasone 10mg QDS
Patient has bacterial meningitis. They have been started on ceftriaxone at 0800. At 2200 that evening, the doctor goes to prescribe dexamethasone. Is this ok and why>
No, if dexamethasone hasnt been started within first 12 hours of antibiotic therapy then don’t include it
What is the purpose of using dexamethasone in the treatment of bacterial meningitis?
It is used to cover pneumococcal organism.
If the organism comes back and IS pneumococcal, continue dexamethasone for 4 days.
If the organism comes back and is a DIFFERENT ORGANISM, stop dexamethasone
Patient with a gradual onset of stupor and confusion. What is the likely diagnosis?
encephalitis
Management of encephalitis
IV aciclovir
Meningitis clinical features
Severe Headache Neck stiffness Non blanching rash N+V Confusion Drowsy Severe muscle pain
Age 10-21, what is the most likely organism causing bacterial meningitis?
Neiserria meningitides
Age over 21, what is the most likely organism causing bacterial meningitis?
Strep pneumoniae
then Neiserria meningitides
Patient having neurosurgery and gets bacterial meningitis. What is the most likely causative organism?
Staph aureus
Patient has fractured cribriform ethmoid plate and gets bacterial meningitis. What is the most likely cause?
Strep pneumoniae
Patient has basilar skull fracture and gets bacterial meningitis. What is the most likely causative organism?
Strep pneumoniae
Most common causative organism of bacterial meningitis in children under 4 years old?
Haemophilus influenzae B
antibiotic of choice for treatment of listeria infection?
Amoxicillin
or Ampicillin
For meningitis, in which patients is penicillin resistant pneumococci a posibility?
Travelers
- give them prophylactic IV vancomycin or PO rifampicin
Treatment of bacterial meningitis in a patient who is allergic to ceftriaxone?
Chloramphenicol
Every patient with suspected bacterial meningitis should get a lumbar puncture. true or false?
False
- only if clinically feasible
Typical CSF findings for bacterial meningitis
- predominant cells
- WBC count (high/low)
- protein (high/low)
- glucose (high/low)
abundant neutrophils
WBC = high
Protein = high
Glucose = low
Typical CSF findings for viral meningitis
- predominant cells
- protein (high/low)
- glucose (high/low)
lymphocytes
protein = normal, maybe slightly high
glucose = normal
Typical CSF findings for TB meningitis
lymphocytes
protein = very high
glucose = low
Provided the patient’s airway, breathing and circulation are under control, what is the initial management of meningitis in the hospital setting?
Blood for blood culture
Initial Tx (ceftriaxone, dexamethasone)
Throat swab
Some patients need to undergo CT prior to lumbar puncture. Which patient groups are these?
Immunocompromised patients Hx CNS disease New onset seizure Papilloedema Focal neurological deficit
In bacterial meningitis, which should be given first….antibiotics or lumbar puncture?
Antibiotics first
- if LP will be performed under 30 mins then can do LP first. otherwise, antibiotics first
Management of bacterial meningitis in patients with GCS < 12 or fluctuating consciousness levels
Secure airway high flow oxygen IV 2g ceftriaxone IV dexamethasone 10mg DO NOT WAIT FOR CT / LP
All clinically suspected meningitis cases must be reported to public health. True or false?
True
Contact prophylaxis regieme for bacterial meningitis
PO rifampicin 600mg 12-hourly for 4 doses
Pseudomonas aeruginosa is a gram negative bacilli. true or false?
True
Pseudomonas aeruginosa is a coliform. True or false?
False
Best antibiotic to treat a pseudomonas aeruginosa infection?
Ciprofloxacin
Ciprofloxacin is safe / unsafe to use in pregnant woman
unsafe
Which 2 groups of people should you NOT do urinalysis on
Elderly patients
Catheterised patients
In urinalysis (dipstick urine), what features point towards a UTI diagnosis
Leukocyte esterase (indicates presence of WBC) Nitrites (indicates presence of bacteria in urine)
Urine microscopy is a common investigation for UTI. True or false?
False
- only in selected (urgent) cases
Over 10 to the power ?? of organisms/ml urine suggests a probable UTI
Over 10 to the power 5 (10^5)
For a lower UTI, ideally the antibiotic used should be excreted where ?
Excreted in the Urine
What is abacterial cystitis
Patient has symptoms of Lower UTI
No organisms grown on culture
Define asymptomatic bacteruria
Over 10^5 organisms/ml urine present
Patient is asymptomatic
Antibiotic treatment is required for asymptomatic bacteruria. True or false?
False
- not required
Which one group of patients requires antibiotic treatment for asymptomatic bacteruria?
Pregnant woman
Gentamicin is safe / unsafe to use in pregnancy?
Unsafe
Which UTI antibiotic should be avoided in the first trimester?
Trimethoprim
Which antibiotic is ONLY for lower UTI and not used to treat upper UTI
Nitrofurantoin
What is a c.diff infection?
- Patient receives antibiotics.
- This alters normal gut flora
- Pts are exposed to c.diff and can become colonised
- A - asymptomatic colonisation
- B - c. diff multiplies and releases toxins causing c.diff infection
Name the 4 C antibiotics
Co-amoxiclav
Cephlasporins
Ciprofloxacin
Clindamycin
What is the main risk factor for the development of C. diff infection?
Previous exposure to antibiotics
What is the most common bacterial cause of healthcare associated GI infection in adults?
C. diff
What is the main symptom of c. diff infection?
Diarrhoea
When do symptoms of C.diff usually occur?
Between day 4 and day 9 of antibiotic treatment
How is c.diff spread
Faecal-oral route
How does c.diff bacteria most commonly get into the environment?
Diarrhoea
Where should a patient with c. diff infection be treated?
Side room
How should you perform hand hygeine when faced with c. diff infection?
SOAP AND WATER
When is a patient considered to be clear of a c diff infection?
if patient has been symptom free for over 48 hours
A young male patient has a 3 day history of pain and swelling in his left knee. He is a keen footballer and developed his symptoms 3 days following trauma to his knee. His temperature is 38ºC, respiratory rate 16 per minute and pulse 60 per minute. He has a hot, swollen left knee with tenderness along the joint margins and a reduced range of movement. What is the likely diagnosis?
Septic arthritis
In a young otherwise fit patient with septic arthritis, what is the most common causative organism?
Staph aureus
A 30 year old immigrant from India with a history of non productive cough, weight loss and night sweats for three weeks. Chest x-ray shows right apical consolidation. What is the likely diagnosis?
TB
A 30 year old immigrant from India with a history of non productive cough, weight loss and night sweats for three weeks. Chest x-ray shows right apical consolidation. Given the likely diagnosis, what is the most appropriate diagnosis that would help support the diagnosis?
Bronchoscopy with lavage
A young child is admitted with abdominal pain and bloody diarrhoea for 4 days. Renal function indicates renal failure. What test is most appropriate to diagnose the likely source of infection?
- stool toxin test
- stool microscopy
- stool culture
stool culture
Patients admitted for elective joint replacements (eg hip, knee) should receive prophylactic antibiotics before the surgery. True or false?
True
For patients receiving prophylactic antibiotics before joint replacement, how long should the course of antibiotics be
No longer than 24 hours
Name 3 blood borne viruses
HIV
Hep B
Hep C
IVDU and phlebotomist gets a needlestick injury. What infection is most likely to be acquired following exposure to this patient?
- Hep C
- HIV
Hep C
Which hepatitis is a common and important cause of liver disease in the UK
Hep C
What is the treatment for giardia infection
Metronidazole 5 days
