Infectious diseases- Medicine Flashcards
Malaria- uncomplicated falciparum treatment
Artemether with lumefantrine (artemesinin combination therapy)
Or oral quinine plus doxycycline
Malaria- complicated/ severe Falciparum treatment
IV artesunate
IV quinine if artesunate not immediately available- continue till pt can complete full oral course of quinine
Malarial prophylaxis
Malarone = proguanil + atovaquone
Mefloquine (weekly)
Doxycycline
Malaria endemic areas (WHO)
Sub-saharan Africa- majority cases
Others- SE Asia, Eastern Mediterranean, Western Pacific, the Americas
Salmonella- gram pos or neg?
Gneg
Aerobic
Typhoid transmission
Faecal-oral route
Contaminated food and water
Relative bradycardia + fever…
= typhoid fever- pulse rate slow for high fever
Rose spots = ?
On chest and abdomen
Typhoid fever
Mx typhoid fever
IV ceftriaxone 2g OD
or Azithromycin
or PO Ciprofloxacin (once sensitivities identified)
Define PUO
Prolonged fever of > 3 weeks which resists diagnosis after a week in hospital
Typical exam Q patient with Tb
Productive cough
Sputum grows acid fast bacilli
Zeihl Neelson staining: red
Latent TB treatment
3 months isoniazid and rifampicin
or 6 months isoniazid alone
Active TB treatment
Rifampicin and isoniazid for 6 months
Pyrazinamide and ethambutol for first 2 months too
Side effects of Rifampicin
General- nausea, thrombocytopoenia, vomiting
Orange urine/ tears
Drug induced hepatitis
Reduces COCP efficacy/ other drugs that use CYP450 - is a potent liver enzyme inducer
(Red-and-orange-pissin)
Side effects of Isoniazid
Peripheral neuropathy (reduced by giving pyridoxine)
Colour blindness
Gynaecomastia
Drug induced hepatitis
Why is isoniazid given with pyridoxine?
Pyridoxine = B6
to reduce side effect of peripheral neuropathy that isoniazid can cause
(I’m-so-numb-azid)
Side effects of Pyrazinamide
Hyperuricaemia - gout
Arthralgia, myalgia
Drug induced hepatitis
Side effects of ethambutol
Optic neuropathy/ reduced VA/ colour blindness
-Check VA before + during treatment
(EYE-thambutol)
Causes of erythema nodosum
Throat infections- strep primary TB Parasitic infections- amoebiasis Chlamydia HSV Viral hepatitis HIV
Inflammatory causes- IBD, sarcoidosis, lymphoma, leukaemia
What is ghon complex
Ghon focus (small lung lesion due to TB) plus hilar lymph nodes - usually in apical segment of R lower lobe
Where to look when given a TB CXR and you can’t see anything
Check the R middle zone
and upper zones -the most aerated portion of the lungs and tubercle bacilli like them
Pt exposed to HIV, no symptoms- do you test?
Yes at 4 wks
Then at 12 wks if negative result
What CD4 count = end stage HIV/ AIDs
Under 200
Risk of opportunistic infections eg PCP or cyatomegalovirus infection
HIV prophylaxis against PCP?
For CD4<200
Co-trimoxazole (septrin)
HIV Vaccinations
Yearly influenza Pneumococcal once or twice a decade Hep A and B Tetanus Diphtheria Polio Avoid live vaccines
Who is offered ART
Anti-retroviral therapy
everyone with HIV regardless of viral load or CD4 count
When do people develop HIV antibodies by
4-6 weeks normally
definitely by 3 mnths
Screening HIV in pregnancy…
NICE recommends screening all pregnant women
Can HIV women breastfeed
No
What is meningococcous
Neisseria meningitidis
Gneg
diplococci
Most common cause of meningitis
Adults- Meningococcus
Pneumococcus (strep pneumoniae)
Neonates to 3mnths- GBS (group B strep)
HI in up to 6yrs is also a possibility
Suspected meningitis + non-blanching rash, seen in GP, what to do?
Urgent IM benzylpenicillin (Or IV) prior to transfer to hospital
Suspecting meningococcal meningitis
Why do we give dexamethasone in bacterial meningitis
To reduce the deafness and neurological damage
Typical abx treatment for bacterial meningitis
Under 3mnths- cefotaxime + amoxicillin
Over 3mnths- ceftriaxone
(cephalosporins) IV
Vancomycin can be added if risk of resistant pneumococcal infection
When is amoxicillin added to cephalosporin treatment for bacterial meningitis
Cover for Listeria- for >55 years, or immunocompromised, or <3mnths
If a patient with TB develops a headache and neck stiffness what might you be concerned about and how would you investigate this further?
Meningitis
Lumbar puncture= high protein, low glucose, lymphocytosis
MRI scan- leptomeningeal enhancement
Where does spinal cord end
L1-2
Where to do LP
L3-4 intervertebral space
Results of lumbar puncture for viral infection
Clear appearance Normal to high protein Normal glucose High WCC and lymphocytes Negative culture
Results of lumbar puncture for bacterial infection
Cloudy appearance High protein Low glucose High WCC and neutrophils Positive bacterial culture
Types of TB that can occur
Pulmonary TB TB meningitis Pericardial TB Disseminated/ military TB Cutaneous TB affecting the skin
Antibiotic choice- staph aureus cellulitis
Flucloxacillin
How do penicillins work
Cell wall synthesis inhibitor
What are beta lactams
Pencillins and cephalosporins
Antibiotic choice- strep skin infection
Benzylpenicillin or flucloxacillin
Penicillin allergy- skin infections
Tetracyclines- doxycycline
Carbapenem- meropenem
Cephalosporin- ceftriazone
Antibiotic choice- strep pneumoniae CAP
Penicillin- amoxicillin
Macrolide- erythromycin, clarithromycin
5 days or 7-10 days depending on severity
Antibiotic choice- atypical pneumonia
Doxycycline (broad spectrum)
Macrolides- erythromycin, clarithromycin
Fluoroquinolones- ciprofloxacin
Mechanism of action of fluroquinolones
Inhibits DNA gyrase- targets DNA
Mechanism of action of macrolides
Erythromycin, clarithromycin, azithromycin
Protein synthesis disruption - inhibit 50s ribosome unit
Antibiotic choice- MRSA
Resistant to beta lactams due to modification of pencillin-binding protein
Instead use glycopeptides- vancomycin, teicoplanin
Or gentamicin (aminoglycosides)
How do aminoglycosides work
Target protein synthesis
Inhibit 30s ribosome subunit
Abx for E coli gastroenteritis?
None
As use of abx increases risk of haemolytic uraemic syndrome (vomiting, bloody diarrhoea, abdominal cramps)- E Coli 0157, shiga toxin
A man presents with severe vomiting. Earlier in the day he re-heated rice
Cause?
Bacillus cereus
- causes vomiting within 6 hrs
Diarrhoea after 6hrs
Gastroenteritis- severe- Antibiotic choice-
Ciprofloxacin
Azithromycin
Antibiotic choice- Salmonella typhi
IV ceftriaxone or azithromycin
Antibiotic choice- profuse diarrhoea caused by C difficile
Metronidazole PO or vancomycin on second episode
Antibiotic choice- visceral infection or peritonitis- eg spleen abscess
co-amox or cipro or aminoglycoside eg gentamicine
+ anaerobic cover- metronidazole
If severe infection or penicillin allergy- carbapenem
What are carbapenems
Cell wall synthesis inhibitors
Very broad spectrum including anaerobes
Safe in penicillin allergies
Antibiotic choice- HSV- encephalitis
IV acyclovir
Antibiotic choice- endocarditis
Strep viridans- benzylpenicillin +/- gentamicin
Enterococci- amox +/- gent
Antibiotic choice- endocarditis in IVDU
Likely staph aureus as a cause- flucloxacillin
Consider bacillus cereus as a cause too
Antibiotic choice- sepsis
Meropenem (stat dose) (carbapenem=targets cell wall-beta lactam ring)
Antibiotic choice- Exacerbations of chronic bronchitis
Amoxicillin or tetracycline or clarithromycin
Antibiotic choice- Pneumonia possibly caused by atypical pathogens
Clarithromycin
Antibiotic choice- LUT
Trimethoprim or nitrofurantoin
Severe- IV co amoxiclav
Antibiotic choice- acute pyelonephritis
Broad spec cephalosporin or quinolone
Antibiotic choice- throat infections
Phenoxymethylpenicillin
If allergic-erythromycin alone
Antibiotic choice- chlamydia
Doxycline or azithromycin
Antibiotic choice- gonorrhoea
IM ceftriazone
Antibiotic choice- bacterial vaginosis
Oral or topical metronidazole or topical clindamycin
Aminoglycosides-examples and side effects
Nephrotoxicity
Ototoxicity
Gentamicin
Tetracyclines- examples and side effects
Discolouration of teeth, photosensitivity- tell pt to wear sunscreen
Oesophagitis and swallowing problems
Doxycycline
Clindamycin- side effects
Common cause of C diff
Macrolides- examples and side effects
Erythromycin, clarithromycin, azithromycin Nausea esp erythromycin P450 inhibitor Prolonged QT Interferes with warfarin/ INR
What antibiotic is commonly associated with C difficile infection
Clindamycin
Vaccinations to avoid in HIV pts
Live attenuated vaccines- BCG MMR oral polio yellow fever oral typhoid Influenza- intranasal
Ix of choice for asymptomatic chlamydia pts
NAAT
Male- first pass urine
Female- vulvovaginal swab
Fever on alternating days, recent travel…
Malaria
Legionella typically colonises where..
Air-conditioning systems
Foreign holidays
Atypical pneumonia- legionella- diagnosis?
Urinary antigen test
Antibiotic choice- pregnant lady with symptomatic UTI
First line- nitrofurantoin but avoid near term
Second line- amoxicillin or cefalexin
TRIMETHOPRIM IS TERATOGENIC IN 1ST TRIMESTER JUST AVOID IT ALTOGETHER
Antibiotic choice- campylobacter
Clarithromycin
Antibiotic choice- pneumonia secondary to influenza
Classically caused by staph aureus
Flucloxacillin
Pneumonia in an alcoholic
Klebsiella pneumoniae
Green offensive chronic ulcer in diabetic pt
Pseudomonas
Infectious mononucleosis classic triad
sore throat, pyrexia and lymphadenopathy
Antibiotic choice- animal bite
Co-amoxiclav
Antibiotic choice- meningitis
Benzyl – P – enicillin –> Pre-hospital treatment (e.g. GP)
Cefo – T – axime –> T - reatment
Ci – Pro– floxacin –> Pro - phylaxis
Antibiotic choice- chlamydia
doxycycline
Antibiotic choice- gonorrhoea
IM ceftriaxone