Infectious diseases Flashcards
E.G Gram positive
Strep, Staph
C.diff - Anaerobic bacilli
E.G Gram negative
E.coli Klebsiella Salmonella shigella Vibrio cholera Neisseria (meningitidis, gonorrhoea)
Non Gram staining Bacteria
Mycobacteria (Ziehl-Neelsen)
Chlamydia e.g. Trachomatis (obligate intracellular)
Vancomycin / Teicoplanin Pathogen and SE
Severe sepsis (MRSA, C.diff)
SE: nephrotoxic, ototoxic
CI: renal fail, deafness
Benzylpenicillin
Pathogen and SE
Strep infections inc pneumoniae, Neisseria (meningitidis & gonococcal), syphilis
SE: hypersensitivity/anaphylaxis
CI: allergic
Flucloxacillin Pathogen and SE
Staph aureus Strep pyogenes (GrpAS)
SE: hypersensitivity/anaphylaxis
CI: allergic§
Amoxicillin Pathogen and SE
UTIs, RTIs
Enterococcal infection
SE: nausea & vomiting
CI: Penicillin hypersensitivity
3rd gen Cephalosporins E.G. + Pathogen and SE
Ceftriaxone & Cefotaxime (Cefotaxime preferred in Neonates)
Staph aureus
Streptococci, Nisseria (used in meningitis), haemophilus
SE: Abx assoc colitis, Stephens-Johnson
CI: allergy
Penicillin drug examples
Amoxicillin/Co-amoxlclav (with clavulanic acid)
Benzypenicillin
Phenoxymethylpenicillin (Penicillin V)
Flucloxacillin
Beta lactam Abx
Penicillins, cephalosporins
Trimethoprim when used, SE and CI
UTI, prostatitis, acute/chronic bronchitis
CI in preg (folate synth inhibitor) - use nitrofurantoin instead, blood dyscarias
SE: hyperkalaemia, depressed haematopoiesis
Metronidazole when used, CI + SE
Anaerobes, Prophylaxis in GI surgery
SE: taste disturbance, anorexia
CI: interaction with alcohol - profuse vomiting
Chloramphenicol main indication & SE
H-influenzae b Epiglottitis
SE: Aplastic anaemia, optic neuritis, erythema multiforme
Macrolide e.g., used against & SE
Clarithromycin&Erythromycin
(Good substitiute if allergic to penicillin)
Strep pneumoniae, Staph aureus, legionella, Chlamydia
SE: Arrhythmia, Stephens-Johnson
CI: hepatic impairment
Doxycycline used against & SE
Broad spec
Strep (pneumoniae, viridians, pyogenes)
Staph aureus, chlamydia
SE: photosensitivity, oesophageal irritation
Aminoglycosides e.g., used against & SE
Gentamycin&streptomycin
Gent used against staph aureus, gram -ve bacilli (e.coli etc)
Used for severe sepsis
SE: nephrotoxic, vestibular/auditory damage
HIV pathophys
Enters cell via receptor (GP120) on virus binding to CD4 on T-cells, Macrophages, monocytes, glial cells
CD4 cells migrate to lymphoid tissue -> viral replication -> new visions to new Th-cells
Subsequent damage and depletion of CD4 cells = dec immune function
How doe HIV viral replication occur
Reverse transcription (error prone - allow viral mutation and escape) and genomic integration (integrase)
Transcription of viral mRNA by CD4
mRNA translated into new proteins = new virus -> budding
Why doesn’t HIV generate an immune response?
Low magnitude of HIV antibodies prod.
Glycoprotein envelope poorly immunogenic
Mutation prone reverse transcription = viral mutation = viral escape
Transmission and who at risk
Blood, sex, vertical (mother to child)
IVDU, african, commercial sex worker, multiple partners
Life expect HIV when is this less
Near normal
X10 risk of death if late diagnosis
When to suspect HIV
Generalised lymphadenopathy
Acute rash
Flu-like/Glandular fever like
Prolonged herpes simplex (cold sores)
mouth lesions
Unexplained weight loss & night sweats
Recurrent bacterial infection
HIV diagnosis
1) ELISA (assay looking for HIV Antibodies and antigens)
2) Western blot (expensive and confirmatory)
3) Serum p24 (HIV antigen)
4) Serum CD4/HIV RNA (PCR)
When is HIV detectable
Assay tests +ve in 95% at 4 week and 99% at 12 weeks
p24 detectable at 4 weeks
HIV severity parameters
Treatment aim
CD4 count
Viral load
Used to determine how advanced and to monitor Tx response
CD4 over 400cells/mm3
Viral load = 0
Normal CD4 range
450-1600 cells/mm3
Stages of HIV
Seroconversion: (antibody to HIV detectable in blood, antigen undetectable)
- Fever, aches, rash, headache, diarrhoea, mouth ulcers
Asympt:
- May last years
- Progressive loss of CD4
- 30% generalised lymphadenopathy
Symptomatic HIV:
- Opportunistic infection
- Kaposi sarcoma/lymphoma
AIDS:
- Worsening of symptomatic
- Pyrexia, night sweats, diarrhoea, Wt lss
- Oral candida/herpes zoster/simplex
AIDS:
- Def
- When dev
- Diag
Acquired immune deficiency syndrome
HIV without Tx in 5-10 years
HIV +ve + AIDS defining condition (Pneumocystis pneumonia, CMV, TB, Toxoplasmosis - brain lesion, tumour - kapok’s sarcoma or lymphoma)
Opprtunistic infections in HIV
TB Pneumocystis pneumonia (fungal) Candidiasis (oral/bronchial/oesophageal) Cryptococcal meningitis Toxoplasmosis SMV
Cancers in HIV
Burkitt’s lymphonma (NHL)
Kaposi’s sarcoma (HHV8)
HIV organ system effect:
Lung GI Eye CNS Psych Cancer
Lung: - TB, S.pneum, H.inf GI: - Oral candida - Salmonella, C.diff Eye: - CMV retinitis -Toxoplasmosis eye disease CNS: - Cerebral toxoplasmosis (Ring on CT) - TB meningitis - CNS lymphoma Psych: - HIV dementia Cancer: - HPV: cervical ca - HHV: Kaposi - EBV: NHL (Burkitt)
Prophylactic Abx in HIV:
Co-trimoxazole (toxoplasmosis,)
Isoniazid ± Rifampicin
Methods of preventing HIV
Reduce vertical transmission
Behavioural: sex-ed, condoms
HIV Tx
- therapy name
- how it works
- how many
HAART (highly active antiretroviral therapy)
Inhibit enzymes involved in RNA reverse transcription, HIV cell fusion etc
Use at least 3 antiretrovirals
How antiretrovirals work
Prevent DNA chain forming from RNA
Block viral reverse transcriptase
Block cleavage of active proteins to form virions
Block entering CD4
Post-Exposure prophylaxis HIV
4 week course Tenofovir + Emtricitabine + Raltegravir
Given 1hr –> 3 day from needlestick (0.3-0.5% transmission risk for needlestick)
E.g. of antiretrovirals
just to see
Tenofovir Emtricitabine Raltegravir
Enfurvitide
Ritonavir
What HAART compliance is needed?
a 95% compliance is needed for good response
Vertical HIV transmission
- methods
- risk %
- prev
From delivery or breast milk
25-40% risk
HAART to mother form end of T1
C-section unless viral load less than 50
Post-natal infant zidovudine mono therapy for 4w (takes risk to 1%)
Viral haemorrhage fevers:
- Filovirus e.g.
- Flavivirus e.g.
Ebola
Zika, Yellow fever
Notifiable diseases
Ebola
- where from
- mech
Bats
Work by inc vascular permeability.
Causes mucous membrane haemorrhage, hypovolaemia, shock and circulatory collapse
Viral haemorrhage fever Pres
Overseas travel to affected area
Flu-like symptoms: temp, sore throat, headache, myalgia, N&V
Maculopapular/petechial rash, hypotension, mucus membrane haemorrhage
Viral haemorrhage fever investigations
LFT: elevated transaminases
FBC: leukopenia, thrombocytopenis
Coal: PTT and INR prolonged
DIC: D-dimer high, fibrinogen low
Amoebic liver disease
- organism
- pres
- Ix
- Tx
Entamoeba histolytica (tropical illness_
Fever. RUQ pain (Referred to R shoulder), Wt loss
signs: hepatomeg, pallor, jaundice
Stool antigen, serum antibody, Liver USS
Metronidazole ± aspiration
Giardia - Transmission - Pres - Ix Tx
Oral ingest (tap water, salads mainly)
diarrhoea (weeks), burping, abdo bloating and pain
Stool microscopy (trophozoites), ELISA stool antigen test
Metronidazole
Typhoid
- organism
- trans
- pathophys
Salmonella typhi
Faeco-oral (food/water)
Adhesion & invasion through gut wall, spread through reticuloendothelial system (spleen, BM)
Typhoid
- pres
- Ix
- Tx
- complications
Fever, frontal headache, malaise, Prostration (very weak)
FBC, LFT (transaminase high), blood/stool/BM culture may show
Ceftriaxone or azithromycin
Fluids
Antipyretics (para)
Chronic carriage (biliary, hepatic), bowel perforation
Dengue
- Spread
- Pres
Mosquito
Fever, rash, flushing, haemorrhage fever, (DIC, hepatomegaly, pleuritic effusion, circulatory collapse)
LFT: transaminase high, albumin low (leaky vessels), IgM +ve serology
Oral//IV fluids, antipyretics, NOTIFICATIONS
Schistosomiasis
- Pathology
- Sympt
- Ix
- complication
Eggs in bladder. haematologinous spread to liver = chronic liver disease
fever, abdo pain, haematuria
Urine microscopy - direct visualisation of eggs
Bladder cancer (from chronic inflammation)
Chlamydia
- Type of organism
- Sympt
- Ix
- Tx
Obligate intracellular
Dysuria, discharge
First catch urine, nucleic acid amplification testing
Contact tracing, Azithromycin (single oral), Doxy
Gonorrhoea
- Type of organism
- Sympt
- Ix
- Tx
Gram -ve diplococci
Dysuria, purulent discharge
nucleic acid amplification testing, gram stain
Contact tracing,
IM ceftriaxone, Azithromycin
Thrush
- Type of organism
- Sympt
- Tx
Candida
White curds, Itch
Fluconazole
Syphilis
- Organism
- Pres (primary, secondary, tertiary)
Spirochete - Treponema pallidum
Primary: local papule / ulcer (Chancre), lymphadenopathy
Secondary: rash on plasma, soles, trunk, alopecia
Teritary: end organ complication after years of infection (dementia, ataxia, aortic regurgitation (diastolic murmur)
Syphilis
- Ix
- Tx
Swab and microscopy
LP/CSF analysis
CXR + ECHO (aortic regurgitation)
IM benzylpenicillin + Prednisolone
Syphilis prognosis
65% no sequelae
10% neurosyphilis (doral column degen - paralysis, dementia) at 10 years
10% CV syphilis at 20 years
Malaria
- What is
- Where
- Types
Plasmodium parasitic infection
90% cases/deaths in Sub-Saharan Africa
Falciparum (most dangerous, Africa/SE Asia)
Vivax, Ovale, Malariae, Knowlesi
Malaria RF
Endemic area, no chemoprophylaxis, no physical barriers (bed net)
Preg
Immunocompromised
Olde
Who protected against Malaria
G6PD
Sickle cell
Which cells affected in malaria
Erythrocytes
Liver
Parasite divides in cells until cells rupture and spill out parasite to infect other cells
Problem with malaria Prev/Tx
Resistance is a problem
Prevention Falciparum
Chloroquine sensitive: Chloroquine, hydroxychloroquine (1w prior, 4w after)
Resistant: Doxy (1-2 days prior, 4w after)
Primary prevention Malaria
Avoid outdoor after sunset Insect repellent Long sleeves Insecticide treated bed nets Antimalarial chemoprophylaxis
Malaria Symptoms
Fever (chills, rigors) Headache weakness Myalgia Arthralgia Anorexia Diarrhoea Jaundice Tachycardia & Hypotension Hepatosplenomegaly
Malaria investigation
Giemsa stained thick and thin blood films (parasites within RBC)
Thick film for parasite number
Thin film for species
Tx Falciparum
Chloroquine or hydroxychloroquine
If resistant:
Quinine + Doxy
OR
Artemether + Lumefantrine
Malaria complications
Acute renal failure (dehydration)
Hypoglycaemia
Metabolic acidosis (tissue hypoxia from anaemia and hypovolaemia
Seizure (acidosis, hypoglycaemia)
If a Q mentions Caves or Bats …
Viral haemorrhage fever
Rabies
Histoplasmosis
MRSA
- Resistance to
- What to use
Methicillin resistant Staph aureus
Methicillin is precursor of Flucloxqcillin (resist to beta lactams - penicillin, cephalosporins)
Vancomycin or Teicoplanin
C.Diff
- Causes
- Tx
The C's -Ciprofloxacin Co-amoxiclav Carbapenems Clindamycin (the worst) Cephalosporins
STOP OFFENDING ABx
Metronidazole, Vancomycin for sev
