Infectious diseases Flashcards
What is the first line antimicrobial treatment for CAP?
Co-amoxiclav + clarithromycin
What antibiotic can be given in CAP if penicillin allergic?
Cefuroxime + clarithromycin
What is the first line antimicrobial treatment for HAP?
Doxycycline
What is the first line antimicrobial treatment for infective exacerbation of COPD?
Doxycycline
What is the first line antimicrobial treatment for cellulitis?
Flucloxacillin
What does strep bacteria look like under the microscope?
Gram positive cocci chains (strep = strip)
What does staph bacteria look like under the microscope?
Gram positive cocci clusters
What is the first line antimicrobial treatment for a UTI?
Nitrofurantoin
What is the second line antimicrobial treatment for UTI?
Trimethoprim
When is trimethoprim CI and why?
Pregnancy
Teratogenic as folic acid antagonist
What should you prescribe with trimethoprim?
Folic acid
What is the first line treatment for H pylori?
PPI
Amoxicillin
Clarithromycin/metronidazole
What can cause C diff?
C antibiotics, fluoroquinolones, broad spectrum penicillins
What is the first line antimicrobial treatment for C diff?
Vancomycin
What is the first line antimicrobial treatment for candidiasis?
Nystatin
What is the first line antimicrobial treatment for meningococcal septicaemia?
Cefotaxime (children ceftriaxone)
What antimicrobials can be given for prevention/contacts of meningitis?
Clarithromycin or rifampicin
Name 3 community aquired infections
Pneumonia, meningitis, skin infections, gastroenteritis, UTI, STI
What is sepsis?
A aberrant or dysregulated immune response to an infection resulting in wide spread inflammatory response affecting organs and tissues
Name 3 complications of sepsis
AKI, delirium, shock, multi-organ failure, septic shock
When should the sepsis 6 be completed by?
Within one hour of diagnosis of sepsis
What is the sepsis 6?
- Senior clinician attendance
- O2 if required sats < 92%
- Bloods (lactate, glucose, FBC, U&E, CRP, clotting) + cultures
- IV Abx (max dose, broad spectrum)
- IV fluids (up to 20ml/kg in boluses)
- Monitor -> NEWS2, urine output, lactate (at least hourly)
BUFALO
What should be considered before prescribing antibiotics?
Indication
- Is there an infection?
- Likely pathogen?
- Does it need antimicrobial therapy?
Site of infection
- Does the site affect choice of antimicrobial? ie can it get across BBB or get into prostate? IV/oral?
Patient
- Adverse effects eg risk of C diff, liver/renal function, allergy
- Drug-drug interactions
- Pharmacodynamics with renal/liver impairment
What pathogens can cause CAP?
Strep pneumoniae
HiB
Legionella
What pathogens can cause infective exacerbations of COPD?
Strep pneumoniae
HiB
Moxarella cararrhalis
What pathogens can cause UTI?
E coli
What pathogens can cause cellulitis?
Staph aureus
MRSA
What pathogens can cause bacterial meningitis?
Strep pneumoniae
GBS
N meningitidis
HiB
Listeria
What is Hepatitis B?
Enveloped DNA virus
Name 3 areas in the world where we see higher rates of HBV
East Asia
Africa
Amazon basin
Name 3 groups in the UK where there might be higher rates of HBV
Migrants from high prevalence countries
Minorities - Roma/Slovaks
IV drug users
What are the 2 routes of transmission of HBV?
Vertical - from mother to baby
Horizontal - sexual (much more infective than HIV/HCV), blood transfusions and procedures such as dialysis/operations, needles/sharps, household transmission
What are the 2 antigens of clinical importance in HBV?
Surface antigen - HBsAg
Envelope antigen - HBeAg
(Core antigen)
What is the role of the HBsAg antigen (surface antigen) in HBV?
Detected in blood during current infection, used for diagnostic confirmation
Genetically produced for vaccine use
What is the role of the HBeAg antigen (envelope antigen) in HBV?
Assessment of phase of infection
What 3 antibodies for HBV are of clinical importance?
Surface antibody - HBsAb
Envelope antibody - HBeAb
Core antibody - HBcAb
What is the role of the HBsAb antibody (surface) in diagnosing HBV?
Indicated immunity to HBV following immunisation or infection
What is the role of the HBeAb antibody (envelope) in diagnosing HBV?
Appears in later phase of disease as evidence of immune response
What is the role of the HBcAb antibody (core) in diagnosing HBV?
Found in most people exposed to HBV. Doesn’t differentiate between acute, chronic, or past infection.
Not found in people due to immunisation
What other structure other than antibodies and antigens are important in HBV diagnosis?
HBV DNA
What is the role of the HBV DNA in diagnosing HBV?
Measured and quantified, helps determine grade of replication and activity of the virus
When might you treat acute HBV and why?
Fulminant hepatitis
Can cause liver failure (increasing INR) so treated to prevent liver failure and subsequent liver transplant
What is the definition of a chronic HBV infection?
Infection persisting beyond 6 months
When is HBV frequently acquired and what affect does this have on the rate of acute infections becoming chronic?
At birth/childhood
Birth -> in highly infective mothers 90% risk of becoming chronic
Childhood -> 30-50% risk of becoming chronic
Adulthood -> 5% risk (higher in immunosuppressed)
How can the risk to neonates of becoming infected with chronic HBV be reduced?
HBV Ig and immunisation at birth (risk reduced to 7%)
What is the risk of having undiagnosed HBV?
Complications - cirrhosis/liver cancer
High risk of liver cancer even without cirrhosis
Oncogenic virus
What is the purpose of HBV treatment?
To control viral replication
What is the treatment for HBV?
Pegylated interferon alpha (weekly injectable for 48 weeks)
Oral anti-virals (tenofovir or entecavir ODS)
What advice should be given to HBV carriers?
Avoid having unprotected sex unless partner has been vaccinated and is immune
Avoid needle sharing
Avoid sharing toothbrushes or razors
Avoid drinking alcohol
What is hepatitis C?
BBV
Six genotypes
How is HCV transmitted?
Parenteral -> IV drug usage or infection via blood products before identification and testing of virus, needle stick injuries, unclean tattoo needles
Risk of household transmission low
Sexual and vertical transmission uncommon
What are the symptoms of an acute HCV infection?
Most asymptomatic
15% malaise, RUQ pain +/- jaundice
What is the rate of spontaneous HCV clearance?
15-30%
What is the prognosis of chronic HCV infection?
1/3 develop ESLD within 25 years of infection
1/3 ESLD beyond 25 years
1/3 never progress to ESLD
What are the side effects of HCV infection?
ESLD, hepatocellular carcinoma
Essential mixed cryoglobulinaemia
Membranoproliferative glomerulonephritis
Porphyria cutanea tarda
Autoimmune thyroid disease in women
How is HCV diagnosed?
Hep C antibody test -> if ever been exposed, doesn’t mean actively infection
HCV RNA -> active infection
What clinical assessment occurs for those with HCV?
Baseline liver fibrosis scan
If advanced fibrosis/cirrhosis then screening for hepatocellular carcinoma
Screened for other causes of chronic liver disease and counselled regarding alcohol
Hep A and B vaccination if not immune
What screening is there for hepatocellular carcinoma?
Alpha feto-protein (AFP)
USS
What is the aim of HCV treatment?
Cure
What is the definition of cure in HCV treatment?
Undetectable HCV RNA in blood 12 weeks after end of treatment (sustained virological response SVR12)
What does HCV treatment entail?
8/12 weeks direct antiviral drugs
95% cure rate
Name 3 places where the incidence of TB is high worldwide
SE Asia
Western Pacific
Africa
How is TB spread?
Droplet spread
How is TB diagnosed?
Sputum ideally (depends on infection site)
Acid fast bacilli special stain -> Ziehl-Neelson stain/Auramine-Phenol
Mycobacterial culture
2-8 weeks to grow
Speciation and genotyping resistance
PCR testing
What are the 4 drugs of treatment for TB and their length of treatment?
Rifampicin (6 months)
Isoniazid (6 months)
Pyrazinamide (2 months)
Ethambutol (2 months)
Name the main side effects of rifampicin
Red colouring of urine, sweat, tears, soft contact lenses
Hepatitis
GI upset
Name the main side effects of isoniazid
Parasthesia
Hepatitis
Name the main side effects of pyrazinamide
N&V
Muscle/joint pain
Hepatitis
Name the main side effects of ethambutol
Visual changes
Optic neuritis
How is the treatment regimen different for CNS TB?
12 months
+ adjunctive steroids
What is multi-drug resistance TB?
TB resistance to at least isoniazid and rifampicin due to poor adherence/management of TB
What other infection is highly associated with TB?
HIV
What contact screening can be done to help diagnose TB?
Mantoux test
Interferon gamma release assay (Quantiferon)
What is the chemoprophylaxis for TB?
Isoniazid for 6-9 months
When can you get a false negative from a HIV infection?
2-3 weeks post infection
What 2 markers are important for HIV diagnosis and monitoring?
CD4 count
Viral load
What does CD4 count tell us in terms of HIV?
Determine how immunocompromised patient is
What is a normal CD4 count?
450-1600 per microlitre of patient’s blood
What infections are more common in patients with a CD4 count < 200?
P jiroveccii pneumonia (PCP)
Toxoplasmosis
What infections are more common in patients with a CD4 count < 50?
Mycobacterium avium intracellulare
CMV
What does viral load tell us in terms of HIV?
Quantity of virus per ml of patients serum
If uncontrolled viral load > 50,000
If well controlled undetectable
Name 3 HIV CNS associated illnesses
Dementia
Toxoplasmosis
CNS lymphoma
Encephalitis -> CMV, herpes
Name 3 HIV skin associated illnesses
Molluscom contageousum
Kaposi’s sarcoma
HSV ulcers
Name 3 HIV respiratory associated illnesses
Recurrent pneumonia
TB
Pneumocystitis pneumonia
Candidiasis
Name 3 HIV GI associated illnesses
Cryptosporidiosis diarrhoea
Candidiasis
Hep A/B/C
Anal cancer
Name 3 other HIV associated illnesses
Cervical cancer
Lung cancer
CMV retinitis
What is the treatment for HIV?
Highly Active Anti-Retroviral Therapy (HAART)
At least 3 anti-retroviral drugs -> act on the virus in different ways and reduce emergence of resistance
When should you give antibacterial prophylaxis in HIV patients?
CD4 < 200
What prophylactic treatment can be given to HIV patients?
Co-trimoxazole (against PCP/toxoplasma/bacterial infections, s/e rash/bone marrow suppression)
Nebulised pentamidine (against PCP, administered in negative pressure side room as teratogenic)
Azithromycin (MAI if CD4 < 50)
Valganciclovir (CMV treatment)
What prevention of HIV is there?
Pre-exposure prophylaxis (PrEP)
Post exposure prophylaxis (PEP)
Antenatal screening and treatment for mothers with HIV
What types of immunodeficiency are there?
Congenital
Acquired
Iatrogenic
What can cause acquired immunodeficiency?
Diabetes
Cirrhosis
Renal failure
HIV
What can cause idiopathic immunodeficiency?
Radiotherapy
Cytotoxic chemotherapy
Immunosuppressive medication
Splenectomy
What is a haematopoietic stem cell transplant?
Stem cells from patient (autologus) or donor (allogenic)
Condition regimen to eradicate cancer/bone marrow stem cells
Stem cells infused into patient
Supportive medication given as stem cells graft
Monitor late effects
What is neutropenia?
Low neutrophil count
Who is at higher risk of neutropenia?
Chemotherapy patients who received it in the last 6 weeks
Received in high dose chemotherapy/bone marrow transplant in last year
Haematological condition causing numeric or functional (not working properly) neutropenia
Where are the common infections in neutropenic patients?
IV lines
Oral cavity
Sinuses
Lungs
Skin
Perineal region
Urinary tract
What is neutropenic sepsis?
Life-threatening complication of chemotherapy and haematopoietic stem cell transplant
Can have minimal signs of infection and may not have pyrexia
What should you do with a suspected neutropenic sepsis patient?
Cultures from IV lines, sputum/bronchoalveolar lavage, urine ect
Empirical Abx treatment started promptly
What symptoms might neutropenic patients have when septic?
Pallor
Mottled skin
Tachycardia
Altered mental state
Anxiety
Increased resp rate
What treatment for neutropenic sepsis can be given to autograft/non-transplant patients?
Piperacillin/taxobactam + gentamicin
Mild penicillin allergy -> ceftazidime + gentamicin
Severe penicillin allergy -> teicoplanin + PO ciprofloxacin
What treatment for neutropenic sepsis can be given to allograft patients?
Meropenem + teicoplanin
Mild penicillin allergy -> meropenem + teicoplanin
Severe penicillin allergy -> discuss with micro
Why are solid organ transplant recipients immunosuppressed?
Require continuous immunosuppressant medication to prevent rejection
What infections can be present in patients within the first month of their solid organ transplant?
Nonsocomial: wound infection, pneumonia, IV line infection
Reactivation of previous infection: TB, strongyloidiasis
What infections can be present in patients within the first 1-6 months of their solid organ transplant?
Viral: CMV, EBV, HBV
Opportunistic: PCP, legionella, aspergillosis, listeria
What infections can be present in patients after 6 months of their solid organ transplant?
Progressive viral: CMV, HBV
Opportunistic: PCP, cryptococcus, listeria, nocardia
Community acquired: S pneumoniae, influenze
What biologic drugs are most at risk of causing reactivation of TB or HBV?
Anti-TNF
What vaccinations should be given to patients to patients with asplenia?
Pneumococcal
Meningococcal ACWY
MenB
Annual flu
Name 3 groups of patients in whom live vaccines are CI
Primary immunodeficiency
HIV
Immunosuppressive therapy
What can be given to immunosuppressed patients who have been exposed to measles/chickenpox as post-exposure prophylaxis?
Measles -> IVIg
Chickenpox -> IVIg/acyclovir
What are sewage workers more at risk of?
Gastroenteritis
Hepatitis
Leptospirosis (rats)
What are farm workers more at risk of?
Orf
Coxsackie
Coxiella
What are aberttoir workers more at risk of?
Anthrax
What are the military more at risk of?
Anthrax
What are sex workers more at risk of?
STDs
Syphilis
HBV
HIV
What are health workers more at risk of?
HBV
LRTI
What are canoeist more at risk of?
Leptospirosis
Gastroenteritis
What are cavers more at risk of?
Histoplasmosis
What are trekkers more at risk of?
Lyme disease
Tick-borne diseases
What are fresh water swimmers more at risk of?
Schistosomiasis
Crytosporidia
What can parrots put you more at risk of?
Chlamydia psittacci
What can terrapins put you more at risk of?
Salmonellae
What can rodents put you more at risk of?
Rat bite fever
What can cats put you more at risk of?
Toxoplasmosis
Toxocara
What can dogs put you more at risk of?
Campylobacter
Capnocytophaga
What can tropical fish put you more at risk of?
Mycobacterium marinum
What can IV drug usage put you more at risk of?
HBV
HCV
HIV
Soft tissue infection
Endocarditis
What can a Hx of head injury put you more at risk of?
Meningitis
Sinusitis
What can alcoholism put you more at risk of?
TB
Pneumonia
HIV
What is an antibiotic?
Molecule that works by binding a target site on a bacteria
Points of a biochemical reaction crucial to survival of bacterium
Crucial binding site varies with antibiotic class
What classes of antibiotics interrupt cell wall synthesis?
Beta lactams
Vancomycin
Teicoplanin
Name the 4 types of beta-lactams
Penicillins
Cephalosporins
Carbapenems
Monobactams
Name 3 penicillins
Penicillin V
Flucloxacillin
Amoxicillin/ampicillin
Piperacillin
Name 3 cephalosporins
Cefalexin
Cefuroxime
Ceftriaxone
Ceftazidime
Name a carbapenem
Meropenem
Ertapenem
Imipenem
Name a monobactam
Aztreonam
How do beta-lactam antibiotics work?
Targets peptidoglycan in cell wall
Larger in gram positive bacteria so tends to be more effective in treating gram positive infections
Bind covalently and irreversibly to the penicillin binding proteins
Leads to hypo-osmotic or iso-osmotic environment
Only active against rapidly multiplying organisms
Poorly penetrate mammalian cells so ineffective in treatment of intracellular pathogens
What is targeted in nucleic acid synthesis?
DNA gyrase
RNA polymerase
Name the antibiotic class that targets DNA gyrade
Quinolones
Name a quinolone antibiotic
Ciprofloxacin
Levofloxacin
Moxifloxacin
Name an antibiotic that targets RNA polymerase
Rifampicin
Name another antibiotic that targets nucleic acid synthesis
Metronidazole
What can be targeted in protein synthesis?
50s subunit
30s subunit
Name the antibiotic class + 3 other antibiotics that target the 50s subunit
Macrolides
Clindamycin
Linezolid
Chloramphenicol
Streptogramins
Name a macrolide
Erythromycin
Clarithromycin
Azithromycin
Name the 2 antibiotic classes that target the 30s subunit and an example for each
Tetracyclines -> doxycycline
Aminoglycosides -> gentamicin