Infectious Disease Flashcards
HIV
Pathophysiology
HIV1/ 2 binds to CD4 receptors (via gp120 envelope glycoprotein)
- Viral reverse transcriptase makes DNA copy of RNA genome
- Viral integrase integrates it into DNA
Synthesized!
- Viral protease cleaves into e_nzyme/ building blocks for new virus_
- CD4+ cells migrate to lymphoid tissue where 1000s virions released!
Impairs CD4+ function ⇒ LOW immunity
HIV
5 stages
- Acute; often asymptomatic
-
Seroconversion - primary infection
- ABs detectable
- 2-6wks ambiguous + LAD
- Maculopapular rash (hands/feet)
- Meningoencephalitis (rare)
-
Asymptomatic period
- 30% have PGL (persistent generalized lymphadenopathy)
-
Constitutional symptoms: AIDS-related complex (ARC)
- Pyrexia + Night sweats
- Diarrhoea + Weight loss
- +/- Opportunistic infections
- CD4 count <200cells/mm3
HIV
Diagnosis
-
Serum (/salivary) HIV-Ab by ELISA
- Confirmed by western blot
- Acute or Seroconversion stage
- HIV RNA (PCR)
- Core p24 Ag in plasma
- Repeat ELISA at 6 weeks
HIV
Anti-retrovirals
Classes + Mechanism + Examples
HAART
- Highly Active Anti-Retroviral Therapy
- = Combination of at least 3 drugs
- Typicaly 2 NRTIs + 1 PI or NNRTI
NRTI
- Nucleoside analogue Reverse Transcriptase Inhibitors⇒ Inhibiting DNA synthesis!
- Zidovudine, Didanosine
- Lamivudine, Stavudine, Zalcitabine
PI -AVIRs
- Competitively inhibits aspartyl protease enzyme (involved in viral protein +enzyme production)
- Indinavir
- Nelfinavir, Ritonavir, Saquinavir
NNRTI
- Non-Nuceloside Reverse Transcriptase Inhibitors⇒ Inhibiting DNA synthesis!
- Nevirapine
- Efavirenz
HIV
Anti-retroviral
NRTI SEs
NRTIs
- Lactic acidosis
- Peripheral neuropathy (Didanosine)
- Pancreatitis (Didanosine)
- Anaemia, black nails, myopathy (Zidovudine)
- Lipodystrophy (Zidovudine, Stavidudine)
HIV
ARD
PI SEs
PIs
- Lipodystropy
- *DM, hyperlipidaemia, central obesity** + buffalo hump
- P450 inhibition (Ritonavir)
- Peri-oral pareasthesia (Ritonavir)
- Renal stones, asymptomatic hyperbilirubinaemia (Indinavir)
- Intracranial bleeding (Tipranavir)
HIV
ARD
NNRTI SEs
NNRTI
- P450 interaction (inducer: Nevirapine)
- Rashes + Toxic Epidermal Necrolysis
- High LFTs
HIV
Diarrhoea
Differentials + Diagnosis
- Cryptosporidium ⇒ modified Ziehl-Neelson acid-fast strain = Red Cysts
- CMV
- Mycobacterium avium intraceullulare
- Atypical CD4 <50
- Blood cultures, LFTs
- T: Rifabutin, ethambutol + Clarithromycin
- Giardia
HIV
Immunisations allowed
- Cholera
- Inflenza-INTRANASAL
- Poliomyelitis-ORAL
- TB (BCG)
CD>200
- MMR
- Varicella
- Yellow Fever
HIV
Neurological complicaions
-
Toxoplasma gondii
- 50%, ambiguous
- CT: Multiple RING enhancing lesions
-
CNS Lymphoma: EBV
- CT: huge fat lesion
- AIDs dementia complex
- Progressive multifocal leukoencephalopathy (PML)
- JCV (John Cunningham Virus)
- Cryptococcus (fungal meningitis)
- Encephalitis (HIV, or CMV)
HIV
Oesophagitis
Most likely cause + Treatment
- Oral Candidiasis: Oesophagitis
- T: Fluconazole + Itraconazole
HIV
Kaposi’s sarcoma
Cause, presentation + treatment
Kaposi’s sarcoma
- HHV8 (human herpes virus 8)
- Purple papules/plaques on skin or mucosa
HIV
Most common opportunistic infection
Complication, prevention, diagnosis + treatment
Pnemocystic Jiroveci (Carinii) Atypical Pneumonia
- Complication: Pneumothorax
- CD4+ <200 require ABx prophylaxis
- Diagnosis
- Bronchoalveolar lavage (BAL) + Silver stain ⇒ Cysts
- Treatment: Co-trimoxazole
- Severe: IV Pentamidine, Steroids
HIV
Pregnancy Management
-
Maternal antiretroviral
- Start @ 28 to 32wks (or earlier)
-
Neonate antiretroviral
- Viral load <50: Zidovudine PO 4-6wks
-
Delivery
- Viral load <50 @36wk: C-Section
- Zidovudine infusion 4hrs-Pre⇒Cord clamp
- Bottle feed
Malaria
Pathophysiology
Female Anopheles mosquito bites
- Sporozoites⇒blood
- ⇒hepatocytes ⇒ multiply as schizonts⇒release as merozoites
- ⇒latent hypnozoites (yrs⇒relapse)
- ⇒RBC ⇒Trophozoites ⇒Schizonts ⇒Haemolysis (Merozoites + Cytokines)
Malaria
Species
-
P. falciparum - 48hr
- Inc: 10d
- Fulminating disease (nasty)
- Africa
-
P. vivax - 48hr
- Inc: 10d
- ‘Benign tertian malaria’
- ⇒Hyponozoites
- SE asia
-
P. ovale - 48hr
- Similar to P. vivax but quicker recovery
-
P. malariae - 72hr
- Inc: 40d
- ⇒‘Lie low’ in blood, recrudesce 1-52yr
- ⇒GNitis?
- P. knowlesi (monkeys..)
Malaria (Plasmodium Falciparum)
- Classic presentation
- Fever Paroxysms
- Fever Periodicity
- Grim signs
- 1month flu-prodrome
-
Paroxyms
- Shivering <1hr “I feel cold”
- Hot stage 2-6hr (flushed, dry skin, N+V)
- Sweating 2-4hr
-
Periodicity reflext haemolysis (every 48hr)
- P. Malariae 72hr
- Anaemia, thrombocytopenia, hepatosplenomegaly, jaundice
Grim signs (CHAAC);
- Cerebral malaria; coma/ convulsions
- HyPOglycaemia
- ATN Renal Failure
- Acidosis Lactic
- Chronic illness
- Choleraic malaria
- Vivax⇒Splenic rupture
- Malariae⇒Quartem malarial nephropathy
- ABV Burkitt’s lymphoma
Malaria
Diagnosis + Investigations
- Serial thin & thick blood film (3thick/72hr)
- FBC: Thrombocytopenia+Anaemia
Memorise;
-
Blood film, count & culture
- Thrombocytopenia
- Anaemia
-
Urinalysis+E (U+E) [Hb, protein, casts]
- ATN Renal Failure
- Quartem malarial nephropathy
-
ABGlucose
- Lactic acidosis
- hyPOglycaemia
Malaria
Protective Factors
- Sickle cell trait
- Hereditary elliptocytosis (melanesian ovalocytosis)
- G6PD deficiency
- Some HLA B53 alleles
Infectious Mononucleosis
Glandular fever
Epstein-Barr virus
- Presentation
- Diagnosis
- Management
- Complications
EBV (enveloped DNA) via Saliva infects B-Lymphocytes ⇒ Proliferation Mononuclear T-Cell
- Fleeting macular rash + facial oedema
- Generalised Lymphadenopathy
- Hepatitis + Jaundice
- +Amoxicillin⇒ Jerish-Hexheimer RASH
Diagnosis
- Monospot/ Paul-Bunnel Heterophil AB test
- Viral PCR
- Downy bodies (atypical T-cells)
Management
- Rest + Support
- NO contact sports 8wks (splenic rupture)
Complications
- +Amoxicillin⇒ Jerish-Hexheimer RASH
- Burkitt’s lymphoma
- Hodgekin’s lymphoma
- HIV CNS Lymphoma
- Nasopharyngeal carcinoma
MRSA
- What is it
- Screening protocol
- Management
What
- Methicillin-Resistant Staphylococcus Aureus (MRSA)
- Resistant to Penicillins + Cephalosporins
MRSA screen 2-4wks prior admission in ALL;
- + MSSA (Full Staph) screen: Implant/ high risk surgery
- Swabs
- Anterior nares (nasal)
- Any skin lesion
- Catheterised: CSU (Catheter Specimen of Urine)
- Productive cough: Sputum
- Staph screen/ patient tagged: Perineum swab
Blind management
- >65yrs+transferred from carehome/hospital
- MRSA Hx in past 6months
Management min 5days and rescreen d7
- Single room
- Nasal: Mupirocin 2% 8hrly
- Skin: Chlorhexidine 0.1% + Neomycin 0.5%
- Wash body daily
- Infection
- Vancomycin, Teicoplanin, Linezolid
ESBL, MGNB, CARB screen
- ALL patient (unless hasnt been in hospital/ abroad for 1yr)
- Rectal swab (stoma/ unable: stool sample)
- Catheter: CSU
- Management: Microbiologist
ESBL: Extended Spectrum Beta-Lactamase-producing Bacilli
MGNB: Multi-resistant Gram-Negative Bacilli
CARB: Carbapenemase-producing Gram-negative Bacilli
Vaccination Schedule
5in1
- Diphtheria, Tetanus, Whooping cough (pertussis), Polio and HIB
-
2m, 3m, 4m
- HIB 1yr (with MenC)
- 4in1 3-5yr (all but HIB)
- 3in1 13-18yr (Dip, Tet, Polio)
PCV (Pneumococcal): 2m, 4m, 1yr
Meningitis C: 3m, 1yr (with HIB), 13-15yr, 18-25yrs (students)
Rotavirus: 2m, 3m
MMR: 1yr, 3-5yr,
HPV: 12-13 girls
Measles of MMR
- Vaccination schedule
- Classic presentation
- Complications
Vaccination: 1yr, 3-5yr
Rubeola virus droplet 10d
- ⇒4d fever
- ⇒3C (cough, coryza, conjunctivitis)
- Koplik spot’s (mucosal grey salt grain)
- Maculopapular rash behind ears⇒ head⇒ body
Complications
- Giant cell pneumonia
- SSPE (subacute sclerosing panencephalitis)
Mumps of MMR
- Vaccination schedule
- Classic presentation
- Complications
Vaccination: 1yr, 3-5yr
Paramyxovirus droplet 2wk
- ⇒Parotitis + swelling
Complications
- Orchitis
- Meningitis
Rubella of MMR
- Vaccination schedule
- Classic presentation
- Complications
Vaccination: 1yr, 3-5yr
Rubella: German measles
- ⇒LAD (post-auricular + occipital)
- Erythamatous rash
Complications
- Pregnant: Congenital Rubella Syndrome
Chicken Pox
- Presentation
- Diagnosis
- Treatment
- Complications
Varicella Zoster virus droplet 2wks
Infectious 1d before rash⇒ last crusted spot
- Rash⇒ Papules⇒ Vesicles⇒ Pustules⇒ Crust
- Fever
Diagnosis: PCR for VZV (secretions/ vesicles)
Treatment
- Calamine lotion
- Severe: Aciclovir
Complications
- Chickenpox pneumonitis
- 2ndary Bacterial skin infection (staph aureus⇒ Impetigo)
- Rare: Varicella cerebellitis
Clostridium difficile
- Pathophysiology
- Aetiology
- Treatment
G+ rod anaerobe bacteria⇒ Toxin entero-A + cyto-B
- ⇒Pseudomembranous colitis
Aetiology
- Elderly, Antibiotics, Illness, Hospital
- Low gut flora (Clindamycin)
Diagnosis: Stool culture x3
Treatment
- 1st episode: Metronidazole 10-14d
- 2nd+: Vancomycin
- ⇒Combine is severe
- Isolation, barrier nursing
Tetanus
- Pathophys
- Presentation
- Diagnosis
- Treatment
Clostridium tetani G+⇒ Exotoxin blocks inhibitory motor neurones⇒ Tetanic spasm
- Hypertonicity (2-3m)
- Neck: Trismus (risus sardonicus)
⇒ Truncal muscles
- Neck: Trismus (risus sardonicus)
- Reflex spasms (7-21d)
- Violent sustained muscle contraction
patient conscious
- Violent sustained muscle contraction
Clinical Diagnosis
Treatment
- Human tetanus immunogloblin
- Benzylpenicillin IV
- Sedation
- Wound debridement
Cholera
- Pathophys
- Investigation
- Treatment
Vibrio cholera G- rod via feacal water contamination
- Toxin acting on enterocyte causing secretory Diarrhoea
- Profound dehydration + Low Na, Cl, HCO3-
Investigation
- ABG: Metabolic Acidosis (HCO3- loss)
- Stool culture
Treatment: Fluid balance, ORS/ IVI fluids.
List G- bacteria
Stain pink
- E. coli
- Salmonella
- Shigella
- Neisseria meningitidis
- Haemophilus influenza
- Vibrio Cholera
List G+ bacteria
Stain blue
- Streptococcus
- Staphylococcus
- Listeria
- Enterococcus
- Clostridium tetani
Campylobacter
- Prevalence UK
- Presentation
Campylobacter jejuni
Number 1 Diarrhoea UK
- N+V+D
- Mimics Appendicitis
Shigella
- Species type
- Shigella Dysenteriae
- S. flexnerii
- S. boydii
- S. sonneii
Contents of ORS
1L ORS
- 20g Glucose
- 3.5g NaCl
- 2.5g NaHCO3
- 1.5 KCl
Cytomegalovirus
- Pathophysiology
- Presentation
- Diagnosis
CMV is a herpes DNA virus, sheds in secretions
- Placenta cross⇒ Congenital malformation
- 3-12wks long time!
Diagnosis
- Histology: Owl-Eye nuclei
- CMV PCR
- Low PLT, high WCC, deranged LFTs
Giardia
- Pathophysiology
- Presentation
- Treatment
Giardia intestinalis (lamblia/ duodenale) protozoa producing SB overgrowths
Spread via water (cysts survive there)
- Non-bloody Diarrhoea + Malabsorption symptoms
Treatment: Trinidazole or Metronidazole
Typhoid
Diptheria
Lyme disease
Leptospirosis/ Weil’s disease
