Infectious Diseases Flashcards
Staph:
- Catalase
- Coagulase
Catalase +ve
Coagulase +ve = staph aureus
Coagulase -ve = epidermis
Strep:
- Catalase
- Haemolysis
- Catalase -ve (streps are chains so think a chain is like a ‘-‘ sign
Alpha hameolysis = strept pneumoniae, viridans Beta haemolysis: Group A - pyogenes B - aglactiae D = enterococci
Gram positive cocci types
Staph & Strep
Gram positive rods
ABCDL Actinomyces ? Bacillus cerus Clostridium Diphtheria Listeria
Gram negative cocci
Neisseria N. meningitidus N.gonorrhoea (cocc-i !) Haemophilus Bordetella
Gram negative rod
the ellas!! (basically all the stuff that causes food poisoning) Salmonella Klebsiella Bordetella Legionella Shigella \+ Campylobacter + E.coli + Proteus
Random organisms that don’t stain - atypical bacteria
Mycobacteria
Myocoplasma
Chlamydia
Spirochaetes - use dark field. –> Syphilis, Lyme
Pneumonia following an influenza - most causative organism
Staph aureus
Pneumonia in a COPD pt
Haemophilis influenza
Pneumonia in a younger pt with bilateral consolidation on XR and erythema multiforme
Mycoplasma pneumoniae
Pneumonia with derranged LFTs, dry cough, hyponatraemia after being on a mediterranian hol
Legionella
Pneumocystitis jivrocci
HIV/Immunosuppressed pt
Pneumonia in a bronchiectasis pt
Pseudomonas
CURB 65 results
Confusion - y/n Urea >7 mmol RR >30 BP <90/60 65 yrs
CURB65 score of 2 - how to manage
Transfer to hosp
Give oral OR IV abx –> amox (doxy/clarithromycin if PA)
5 days
CURB65 score of 3+ how to manage
Transfer to ITU
IV co-amox + PO Doxy
OR (if NBM)
IV Co-amox + IV Clarithromycin
Step down to PO Doxy bd
Follow up pneumonia
Repeat CXR 4-6 weeks after to ensure consolidation resolved and no cancer
Investigations for meningitis
Bloods - FBC, CRP, culture, PCR, paired glucose (for LP), ABG
CT - to exclude raised ICP
LP
What is a normal LP interpretation:
- Appearance
- Opening pressure
- WBCs
- Protein
- Glucose
Clear appearance Pressure 7-18 WBCs <4 lymphocytes, 0 polymorophs (a few in kids) Protein 0.15-0.4g Glucose >50% of serum glucose
What type of infection is:
- Clear appearance
- Normal opening pressure
- Lymphocytosis
- Normal-high protein
- Normal glucose
Viral
*Note - partially treated bacterial infections can look viral-y
Mainstay characteristic features of LP
Bacterial - turbid looking appearnace
TB - Lymphocytosis + High proteins + <50% glucose
Viral - Normal glucose
Fungal - similar presentation to TB
Most common cause of meningitis
Most likely - viral
Enterovirus
Most common cause of BACTERIAL meningitis
0-3mnths –> Baby BEL
- Group B strep
- E.coli
- Listeria
18mnths - 50yrs –> NHS
- Neisseria
- H.influenza
- Strep pneumonia
> 50yrs
- NHS + Listeria
How is bacterial meningitis treated?
IV CEFOTAXIME + amox (for listeria cover)
If the patient has meningitis and you can’t get an urgent transfer into surgery - what do you give?
IM benzylpenicillin
If there are signs of encephalitis, what to give?
Aciclovir - 10 days Inf
What to give as meningococcal menigitis prophylaxis?
Give to close contacts
Oral ciprofloxacin or rifampicin
Meningococcal vaccine
Symptoms of encephalitis
Meningial symptoms Altered behaviour Confusion Headache Drowsiness
Causes of encephalitis
Usually viral - HSV-1
If bacterial - usually a complication of menigitis from lyme disease or syphilis
Infections assoc. with Staph aureus bactereamia
Osteomyelitis Septic arthrtitis Psoas abscess Discitis Endocarditis
Symtpoms of discitis
Back pain
Fever
Malaise
Focal neurology
Investigations of discitis
MRI spine
CT-giuded biopsy
If bacteraemia is uncomplicated or complicated, how many days do you treat with fluclox?
Uncomplicated - 14 days
Complicated - 28 days
Endocarditis signs - vascular and immunological
Due to septic emboli: (vascular)
- Janeway lesions
- Conjunctival haemorrhages
- Splinter haemorrhages
- Cerebral infarcts
Immunological:
- Glomerulonephritis
- Osler’s nodes
- Roth spots
Infective endocarditis causative organisms
- Staph aureus
- Coagulase-negative staphs - S. epidermidis
- Strep viridans
- Enterococcus
- HACEK –> Haemophilis….Kingella. Others inbetween, none sound familiar
Diagnostic criteria for IE
Can be pathological or clinical:
Pathological: 1
- Autopsy, biopsy –> vegetations, embolic fragments
Clinical: 2 major or 1 major and 3 minor
Major:
- Blood culture +ve - 2 +ve cultures with characteristic organism or persistently +ve cultures with microorganisms that could be consistent with IE
- Echo positive for vegetation or abscess or dehiscence of prosthetic valve
Minor:
- Pre-disposition e.g. heart condition or prosthetic valve
- Fever >38
- Immune complexes deposits
- Embolic signs
- +ve blood cultures not sufficient to meet major criteria
When would you decide to do a surgical intervention for IE (otherwise medically treated with IV abx for 4-6wks)
Abx resistant
Persistent bactereamia
Myocardial abscess
Prevention of large emboli - if there are large vegetations
Pathophysiology of TB
Primary disease - infected droplet inhaled gives a primary lung infected
Proliferates within alveolar macrophages - granulomatous tubercle
Lung lesion + Lymphadenopathy
Ghon complex
TB with bactereamia and disseminated infection
Miliary TB
Reactivation of TB location
apex of lung
RFs for reactivation
Immunocompromised HIV Steroid use TNFa inhibitors Renal failure
Histology characteristic of TB
Langerhans multi-nucleated giant cells
Invetsigations of TB if active
Sputum culutre (GOLD)
- Assessed drug sensitivities
- SLOW: takes several weeks
Sputum micorscopy
- Commonest in practive
- ZN stains acid fast bacilli
- 3 samples needed
Nucleic acid amplication test (NAAT)
- Rapid diagnosis <48hrs
- Tests for rifampicin resistance
- Less sensitive than culture
CXR
- Upper lobe caviation (reactivated TB)
- Bilateral hilar lymphadenopathy
Investigations of latent TB
IGRA
- Detect T cells response
Tuberculin skin prick test (Mantoux)
- Injected intradermally then wheal measured 72hrs later
- <6mm negative
- 6-14mm - maybe
- <15 strongly suggestive of TB Infection
4 medicines for TB
Rifampicin
Isoniazid
Pyrazinamide
Ethambutol
S/E of 4 treatments for TB
Rifampicin - orange pee
Isoniazid - peripheral neuropathy - prevent this by adding pyridoxine (vit B6)
Pyrazinamide - gout
Ethambutol - optic neuritis (e for eye)
They also all can cause hepatitis
Management time course
Active - 6 months total
2 RIPE
4 RI
Latent
3 mnths R&I
6 mnths I
Meningeal TB
- 12mnths antibitix + steroids
Causative organism for:
- Cellulitis
- Nec fasc
- Gas grangrene
cellulitis:
- staph aureus
- GAS
nec fasc
- GAS
Staph aureus
Gas gangrene
- clostridium perfringes
info of nec fasc
Commonest site = perineum - “Founeirs gangrene”
Seen in IVDU, immunocompromised
Pain out of keeping with physical features
tx of nec fasc
Emergency surgical debridement
Tazocin + Clindamycin
similar tx for gas grangrene
tx of cellulitis
IV fluclox for 5-7 days
Questions to ask for ID
- Where specifically did they go?
- Did they get any pre-travel vaccines
- Sexual contact
- Needle contact
- Freshwater contact
- Animal contact, insect bites
- Accomadation - hostel/hotal/camping
- Street food
- Unsterilized water
Symptoms of infectious mononucleosis
Sore throat
Fever
Lymphadenopathy
Diagnosis of glandular fever
Heterophile antibody test
- Infected B cells produce IgM which agglutinate RCBs
Mx glandular fever
supportive
Early and late features of LYme disease
Early - erythema migricans rash, headache, lethargy
Late features - CARDIO heart block and NEURO facial nerve palsy
Suspect if patient has told you they have been out camping
Ix of lyme disease
ELISA antibodies
Mx of lyme disease
Doxy & amox if early
Late - ceftriaxone
Pathophysiology of botulism
Botulinum toxin inhibits ACh release - causes flaccidness
Pathophysiology of tetanus
tetanus exotoxin inhibits gaba release - causes rigidity
Mx for botulinum and tetanus
Bot - anti-toxin
Tet - metronidazole also tetanus vaccine
HIV diagnosis
You need explicit consent to test for HIV
Serology - antibodies to HIV antigens develop at 4-6 weeks. They can be detected by ELISA.
Get confirmatory western blot
Viral detection is not used in diagnosis, it is used to monitor treatment
Most common infection of AIDS
Pneumocystis pneumonia
Features of pneumocystis pneumonia
dyspnoea (SOB) , dry cough, fever, desaturation on walking
Diagnosis of pneumocystis pneumonia
BAL - sputum
PCR of p. jirovecii
Mx of penumocystis peumonia
High dose co-trimoxazole
IV pentamidine
Mx of HIV
3 HAART drugs
2 nucleoside reverse transcriptase inhibitors (NRTI)
Either protease inhibitor or non-nucleotide reverse transcriptase inhibitor (NNRTI)
Pregnant Tx of HIV
all women screened and offered antiretrovirals if +ve
Vaginal delivery : if viral load <50 at 36 wks, can deliver. If higher, must be C/S
Start Zidovudine before delivery
Neonatal - zidovudine if mother <50, otherwise give triple therapy
DON’T BREASTFEED
Malaria - clinical features
48hr cyclical headache
Malaise
Headache
Diagnosis
Blood smears
Detect LDH antigen
Blood findings - haemolysis, thrombocytopenia, ureamia, hyperbilirubinaemia, abnormal LFTs
History of travel to an endemic area
Malaria mx
most common type of malaria = falciparum
- Uncomplicated = oral ARTeminsin combo therapy
(ARTemether + lumefantrine)
If severe or >2% parasited = give IV ARTesunate
Malaria prophylaxis
Malarone - GI upset - 2 days prior + 7 days after
Don’t give to renal impairment
Chloroquine – headache - 1 week + 4 weeks after
Don’t give to epileptics
Doxy - photosensitivity - 2 days prior + 4 weeks after
Don’t give to pregnancy
Mefloquine - dizziness - 3 weeks prior + 4 weeks after
Don’t give to epilepsy or mental health
Parasites:
1) Eggs in urine
2) Dilated cardiomyopathy + MEGA oesophagus + MEGA colon
3) Hepato + splenomegaly
4) CNS involvement
1) Scistomiasis
2) Chagas
3) Leischmamnn
4) Sleeping sickness
Gatsroenteritis:
non-bloody diarrhoea, recent travel to spain
Tx?
Giardiasis
Metronidazole
Causative drugs of C.diff
Clindamycin, cephalosporins, co-amox
Ix of c.diff
WCC
C.diff toxin in STOOL
Mx of c.diff
1st line - oral metronidazole 2nd line (if severe) - oral vancomycin
What abx to give after an animal bite?
Cp-amox
overgrowth of predominately Gardnerella vaginalisn is what condiiton
bacterial vaginosis
Which gastroenteritis presents with constipation?
Typhoid fever i.e. salmonella
although note: classic salmonella can give diarrhoea
Cellulitis is a PA pregnant person?
Erythromycin
Note: PA people with cellultis - give clarithromycin but because clarithromycin is inappropriate during pregnancy, give eryth
What organism causes pneumonia that is assoc. with cold sores?
Strep. pneumonia (most common causative organism)
Syphilis Mx
IM benzylpenicillin
Stereotypical features of Legionella include?
dry cough, relative bradycardia and confusion. Blood tests may show hyponatraemia
common cause of chronic wound infections
pseudomonas
