Infectious Diseases Flashcards
Bacteria
what can they be categorised into
- aerobic
- anaerobic
- gram +ve
- gram -ve
- atypical bacteria
Bacteria
gram +ve bacteria cell wall
thick peptidoglycan cell wall that stains with crystal violet stain
Bacteria
gram -ve bacteria
don’t have this thick peptidoglycan cell wall and doesn’t stain with crystal violet stain
but will stain other stains
Bacteria
atypical bacteria definition
cannot be cultured in the normal way or detected using a gram stain
most often implicated in pneumonia
Bacteria
what is nucleic acid
essential component of bacterial DNA
Bacteria
what are ribosomes
where bacteria proteins are synthesised within the bacterial cell
Bacteria
what is folic acid essential for
synthesis and regulation of DNA within the bacteria
Bacteria
how does folic acid enter the bacteria cell
the chain starts with PABA, which is directly absorbed into the cell across the cell membrane
PABA is converted to DHFA which is converted to DHFA which is converted inside the cell to THFA then folic acid
Bacteria
what is involved in gram staining a bacteria
- add a crystal violet stain which binds to molecules in the thick peptidoglycan cell wall
- add a counterstain (safranin) which binds to the cell membrane in bacteria that don’t have a cell wall
Bacteria
what colour do gram +ve bacteria turn when gram stained
violet (from crystal violet stain)
Bacteria
what colour do gram -ve bacteria turn when gram stained
pink (from counterstain)
Bacteria
name 3 gram +ve cocci
- staphylococcus (clusters)
- streptococcus (chain)
- enterococcus (diplo)
Bacteria
name the 5 gram +ve rods
Ben Neo Likes My Cat
Bacillus Nocardia Listeria Mycobacteria Corneybacteria
Bacteria
name 4 gram +ve anaerobes
CLAP
Clostridium
Lactobacillus
Actinomyces
Propionibacterium
Bacteria
name common gram -ve organisms (7)
- Neisseria meningitis
- Neisseria gonorrhoea
- Haemophilia influenza
- E.coli
- Klebsiella
- Pseudomonas aeruginosa
- Moraxella catarrhalis
Bacteria
atypical bacteria that causes atypical pneumonia
Legions of Psittaci MCQs
Legionella pneumophila chlamydia Psittaci Mycoplasma pneumoniae Chlamydydophila pneumoniae Q fever (coxiella burneti)
Bacteria
what is MRSA
Methicillin-Resistant Staphylococcus Aureus
Staphylococcus aureus bacteria that have become resistant to beta-lactam abx such as penicillins, cephalosporins and carbapenems
Bacteria
which people should you think about MRSA in
- hospital admissions
- nursing home
healthcare settings where abx are commonly sued
Bacteria
what extra measures can be taken to try to eradicate MRSA and stop spread
pts admitted for surgery or trx are screened by taking nasal and groin swabs
Bacteria
what is involved in eradication of MRSA
chlorhexidine body washes and antibacterial nasal creams
Bacteria
abx trx options for MRSA
- doxycycline
- clindamycin
- vancomycin
- teicoplanin
- linezolid
Bacteria
what are ESBLs
Extended Spectrum Beta Lactamase bacteria that have developed resistance to beta-lactam abx
Bacteria
how are ESBLs resistant to beta-lactam abx
they produce beta lactamase enzymes that destroy the beta-lactam ring on the abx
Bacteria
ESBLs tend to be ____ or ____
e.coli or klebsiella
typically cause UTIs but can also cause other infections eg pneumonia
Bacteria
what are ESBLs sensitive to
carbapenems such as meropenem or imipenem
Antibiotics
define bacteriostatic
abx that stop the reproduction and growth of bacteria
Antibiotics
define bactericidal
abx that kill the bacteria directly
Antibiotics
abx that inhibit cell wall synthesis
with a beta-lactam ring :
- Penicillin
- Carbapenems e.g. meropenem
- Cephalosporins
without a beta-lactam ring:
- Vancomycin
- Teicoplanin
Antibiotics
abx that inhibit folic acid metabolism
- Sulfamethoxazole
- Trimethoprim
- Co-trimoxazole
Antibiotics
how does Sulfamethoxazole work
inhibits folic acid metabolism by blocking the conversion of PABA to DHFA
Antibiotics
how does Trimethoprim work
inhibits the folic acid metabolism by blocking the conversion of DHFA to THFA
Antibiotics
what is Co-trimoxazole a combination of
Sulfamethoxazole and Trimethoprim
Antibiotics
why is Metronidazole effective against anaerobes and not aerobes
the reduction of metronidazole into its active form only occurs in anaerobic cells
when partially reduced, metronidazole inhibits nucleic acid synthesis
Antibiotics
abx that inhibit protein synthesis by targeting the ribosome
- Macrolides: erythromycin, clarithromycin, azithromycin
- Clindamycin
- Tetracyclines: doxycycline
- Gentamicin
- Chloramphenicol
Antibiotics
stepwise process of escalating abx trx
- start with Amoxicillin which covers strep, listeria + enterococcus
- switch to Co-amoxiclav to additionally cover staph, haemophilus, e.coli
- switch to Tazocin to additionally cover pseudomonas
4, Switch to meropenem to additionally cover ESBLs
- Add Teicoplanin or Vancomycin to cover MRSA
6, Add Clarithromycin or Doxycycline to cover atypical bacteria
Sepsis
what is it
a condition where the body launches a large immune response to an infection that causes systemic inflammation and affects the functioning of the organs of the body
Sepsis
pathophysiology
Pathogen recognised by macrophages, lymphocytes and mast cells
they release cytokines, interleukins + TNF which alerts the immune system
Sepsis
what do cytokines do
Cytokines activate NO which causes vasodilation
Cytokines cause the endothelial lining of blood vessels to become more permeable. Fluid leaks out of blood into the extracellular space leading to oedema and reduction in intravascular volume
Sepsis
what does oedema around blood vessels lead to
creates space between blood and the tissues reducing the amount of O2 that reaches the tissues
Sepsis
what does activation of the coagulation system lead to
deposition of fibrin throughout the circulation further compromising organ and tissue perfusion
also leads to consumption of platelets and clotting factors as they are being used up to form clots within the circulatory system
this leads to DIC
Sepsis
what is DIC
disseminated intravascular coagulopathy:
- thrombocytopenia
- haemorrhages
- inability to form clots + stop bleeding
Sepsis
why does lactate increase
due to hypoperfusion of tissues that starves the tissue of O2 causing them to switch to anaerobic respiration
a waste product of anaerobic respiration is lactate
Sepsis
define septic shock
when arterial blood pressure drops and results in organ hypo-perfusion
leads to increased blood lactate as the organs begin anaerobic respiration
Sepsis
how can septic shock be measured/diagnosed
- systolic BP <90 despite fluid resus
- hyperlactatemia (lactate >4mmol/L)
Sepsis
trx
treat aggressively with IV fluids to improve BP and tissue perfusion
Sepsis
trx if IV fluid boluses don’t improve the BP and lactate level
escalate to HDU or ICU where they can use inotropes (noradrenalin) to help stimulate the CVS and improve BP and tissue perfusion
Sepsis
define severe sepsis
when sepsis is present and results in organ dysfunction
Sepsis
severe sepsis examples of organ dysfunction
- hypoxia
- oliguria
- AKI
- thrombocytopenia
- coagulation dysfunction
- hypotension
- hyperlactaemia (>2mmol/L)
Sepsis
RFs
any condition that impacts the immune system or makes the pt more frail/prone to infection:
- very young or old (<1 or >75)
- chronic conditions: COPD, DM
- chemo, immunosuppressants or steroids
- surgery or recent trauma or burns
- pregnancy or peripartum
- indwelling medical devices: catheters, central lines
Sepsis
what is used in the UK to pick up the signs of sepsis
the National Early Warning Score (NEWS)
Sepsis
what does NEWS check
- temp
- HR
- RR
- O2 sats
- BP
- consciousness level
Sepsis
signs on examination
- signs of potential sources: cellulitis, discharge from wound, cough, dysuria
- non-blanching rash: meningococcal septicaemia
- reduced urine output
- mottled skin
- cyanosis
- arrhythmias: eg new onset AF
Sepsis
what is often the first sign of sepsis
high RR (tachypnoea)
Sepsis
what may elderly pts present with
confusion or drowsiness or simply ‘off legs’
Sepsis
what may neutropenic or immunosuppressed pts present as
normal obs and temp despite being life threatening unwell
Sepsis
blood tests for pts with suspected sepsis
- FBC: WCC + neutrophils
- U&Es: kidney function, AKI
- LFTs: liver infection + source of infection
- CRP: inflammation
- Clotting: DIC
- Blood cultures: bacteraemia
- Blood gas: lactate, pH, glucose
Sepsis
what additional inx can be helpful in locating the source of infection
- urine dipstick and culture
- CXR
- CT if intra-abdo infection or abscess is suspected
- LP for meningitis or encephalitis
Sepsis
high risk pts need…
urgent attention + mnx
Sepsis
moderate risk pts ….
may be managed in the community where the dx is clear and it is safe to do so
Sepsis
mnx
sepsis 6 within 1hr
Sepsis
what is Sepsis Six
3 tests:
- blood lactate
- blood cultures
- urine output
3 trxs:
- O2 to maintain O2 sats 94-98% (or 88-92% in COPD)
- empirical broad spectrum abx
- IV fluids
Sepsis
what is neutropenic sepsis
sepsis in a pt with a low neutrophil count of < 1x10(9) /L
Sepsis
medications that may cause neutropenia
- anti-cancer chemo
- Clozapine (schizophrenia)
- Hydroxychloroquine (RA)
- Methotrexate (RA)
- Sulfasalazine (RA)
- Carbimazole (hyperthyroidism)
- Quinine (malaria)
- Infliximab (immunosuppression)
- Rituximab (immunosuppression)
Sepsis
when should you suspect neutropenic sepsis in pts taking immunosuppressants or medications that may cause neutropenia
treat any temperature above 38 as neutropenic sepsis until proven otherwise
Sepsis
why is there a high risk of death from sepsis in pts taking immunosuppressants or medications that may cause neutropenia
their immune system cannot adequately fight the infection
Sepsis
mnx of neutropenic sepsis
Each local hospital will have a neutropenic sepsis policy
immediate broad spectrum antibiotics: piperacillin with tazobactam (tazocin)
aspects of mnx are the same for sepsis but with more caution
Urinary Tract Infections
why are they more common in women
their urethra is much shorter making it easy for bacteria to get into the bladder
Urinary Tract Infections
what is the main source of bacteria
from faeces where the normal intestinal bacteria e.g. E.coli can travel to the urethral opening from the anus
Urinary Tract Infections
methods of spreading bacteria
- sexual activity
- incontinence
- hygiene
- urinary catheters
Urinary Tract Infections
presentation of a lower UTI (6)
- dysuria
- suprapubic pain or discomfort
- frequency
- urgency
- incontinence
- confusion in frail pts
Urinary Tract Infections
presentation of pyelonephritis
- fever
- loin, suprapubic or back pain. Uni or Bilateral
- haematuria
- renal angle tenderness
- looking + feeling generally unwell
- vomiting
- loss of appetite
Urinary Tract Infections
urine dipstick results
nitrites: +
leukocytes: +
Urinary Tract Infections
What to do if
nitrites: -
leukocytes: +
should not be treated as a UTI unless there is clinical evidence
nitrites are a better indication of infection
Urinary Tract Infections
why would nitrites be +ve on a urine dipstick
gram -ve bacteria (E.coli) break down nitrates into nitrites
nitrates are a normal waste product in urine
Urinary Tract Infections
if nitrites and leukocytes are present then what?
send midstream urine to microbiology lab to be cultured and to have sensitivity testing
Urinary Tract Infections
most common organism
E.coli
gram -ve, anaerobic, rod shaped bacteria
Urinary Tract Infections
other causes apart from E.coli
- Klebsiella pneumoniae (gram-negative anaerobic rod)
- Enterococcus
- Pseudomonas aeruginosa
- Staphylococcus saprophyticus
- Candida albicans (fungal)
Urinary Tract Infections
abx choice in the community
- Trimethoprim
- Nitrofurantoin
alternatives:
- Pivmecillinam
- Amoxicillin
- Cefalexin
Urinary Tract Infections
duration of abx for a simple lower UTI in women
3d
Urinary Tract Infections
duration of abx for women that are immunosuppressed, have abnormal anatomy or impaired kidney function
5-10d
Urinary Tract Infections
duration of abx for men, pregnant women or catheter related UTIs
7d
Urinary Tract Infections
what do UTIs in pregnancy increase the risk of?
- pyelonephritis
- PROM
- pre-term labour
Urinary Tract Infections
mnx in pregnancy
1st line: nitrofurantoin
2nd line: cefalexin or amoxicillin
for 7d
Urinary Tract Infections
why is nitrofurantoin avoided in the 3rd trimester
it is linked with haemolytic anaemia in the newborn
Urinary Tract Infections
why is trimethoprim avoided in the 1st trimester
anti-folate effects
Urinary Tract Infections
mnx of pyelonephritis
- refer to hospital if there are features of sepsis
1st line abx for 7-10d:
- cefalexin
- co-amoxiclav
- trimethoprim
- ciprofloxacin
Cellulitis
what is it
an infection of the skin and the soft tissues underneath
Cellulitis
presentation
- bullae
- golden yellow crust
- erythema
- warm to touch
- tense
- thickened
- oedematous
Cellulitis
what are bullae
fluid-filled blisters
Cellulitis
what may a golden-yellow crust indicate
staphylococcus aureus infection
Cellulitis
most common causes
- Staphylococcus aureus
- Group A Streptococcus
- Group B Streptococcus
- MRSA (less common)
Cellulitis
name a Group A strep
streptococcus pyogenes
Cellulitis
name a group B strep
Streptococcus dysgalactiae
Cellulitis
what is the classification system NICE recommend for the assessment of the severity of cellulitis
Eron Classification (Class 1-4)
Cellulitis
Eron Classification: Class 1
no systemic toxicity or comorbidity
Cellulitis
Eron Classification: Class 2
systemic toxicity or comorbidity
Cellulitis
Eron Classification: Class 3
significant systemic toxicity or significant comorbidity
Cellulitis
Eron Classification: Class 4
sepsis or life-threatening
Cellulitis
when should you admit for IV abx
if they are class 3 or 4
consider if frail, very young or immunocompromised
Cellulitis
trx
Flucloxacillin is very effective against staph
PO or IV
alternatively: clarithromycin, clindamycin, co-amoxiclav
Malaria
what is it caused by
members of the Plasmodium family of protozoan parasites
Malaria
what are protozoa
single celled organisms
Malaria
what is the most severe and dangerous member of the Plasmodium family of protozoan parasites
Plasmodium falciparum (75% of cases in UK)
Malaria
how is it spread
through bites from the female Anopheles mosquitoes that carry the disease
infected blood sucked up by feeding mosquito
malaria in the blood reproduces in the gut of the mosquito producing thousands of sporozoites (malaria spores)
mosquito bites another human and sporozoites are injected by the mosquito.
Malaria
4 types
- Plasmodium falciparum
- Plasmodium vivax
- Plasmodium ovale
- Plasmodium malariae
Malaria
where do the sporozoites travel to in the newly infected person
the liver
Malaria
what can P.vivax and P.ovale do in the liver
lie dormant as hypnozoites for several years
Malaria
how sporozoites cause haemolytic anaemia
merozoites mature in the liver into merozoites which enter the blood and infect RBCs
In RBCs, the merozoites reproduce over 48hrs then the RBCs rupture, releasing loads more merozoites into the blood, causing haemolytic anaemia
Malaria
why do infected people have high fever spikes every 48 hrs
in RBCs the merozoites reproduce over 48hrs, after which the red blood cells rupture releasing loads more merozoites into the blood and causing a haemolytic anaemia
Malaria
incubation period
1w after infection with malaria although it can lie dormant for years
Malaria
whom should you suspect malaria in
someone who lives or has travelled to an area of malaria
Malaria
non specific sx (5)
- fever, sweats, rigors
- malaise
- myalgia
- headache
- vomiting
Malaria
signs (3)
- pallor due to the anaemia
- hepatosplenomegaly
- jaundice
Malaria
why do pts get jaundice
because bilirubin is released during the rupture of RBCs
Malaria
dx
malaria blood film (sent in an EDTA bottle) (the red top bottle for FBC)
Malaria
how to exclude malaria
3 samples of blood film are sent over 3 consecutive days
Malaria
why are 3 samples sent over 3 consecutive days
due to the 48 hour cycle of malaria being released into the blood from RBCs
the sample may be -ve on days where the parasite is not released
but +ve later when they are released from the RBCs
Malaria
for advice and mnx, whom should you discuss pts with
the local infectious diseases unit
Malaria
which patients should you admit
all patients with falciparum malaria
Malaria
IV options in severe (falciparum) or complicated malaria
- Artesunate (most effective but not licensed)
2. Quinine dihydrochloride
Malaria
PO options in uncomplicated malaria
- Artemether with lumefantrine (Riamet)
- Proguanil and atovaquone (Malarone)
- Quinine sulphate
- Doxycycline
Malaria
Falciparum complications
- Cerebral malaria
- Seizures
- Reduced consciousness
- Acute kidney injury
- Pulmonary oedema
- DIC
- Severe haemolytic anaemia
- Multi-organ failure and death
Malaria
prophylaxis general advice
- Be aware of locations that are high risk
- No method is 100% effective alone
- Use mosquito spray (e.g. 50% DEET spray) in mosquito exposed areas
- Use mosquito nets and barriers in sleeping areas
- Seek medical advice if symptoms develop
- Take antimalarial medication as recommended
Malaria
antimalarial options
- Proguanil and atovaquone (Malarone)
- Mefloquine
- Doxycycline
Malaria
Proguanil and atovaquone (Malarone) facts
- Take daily 2 days before, during and 1 week after being in endemic area
- Most expensive (around £1 per tablet)
- Best side effect profile
Malaria
Mefloquine facts
- Take once weekly 2 weeks before, during and 4 weeks after being in endemic area
- SEs: bad dreams and rarely, psychotic disorders or seizures
Malaria
Doxycycline facts
- Take daily 2 days before, during and 4 weeks after being in endemic area
- Broad-spectrum abx therefore it causes SEs like diarrhoea and thrush
- Makes patients sensitive to the sun causing a rash and sunburn
Dengue Fever
what is it
a viral infection which can progress to haemorrhagic fever (a form of DIC)
transmitted by the Aedes aegypti misquito
Dengue Fever
incubation period
7d
Dengue Fever
features
- headache (often retro-orbital)
- facial flushing (dengue)
- maculopapular rash
- fever, myalgia, pleuritic pain
Dengue Fever
trx
entirely symptomatic e.g. fluid resus, blood transfusion
no antivirals currently available
Enteric fever (typhoid/paratyphoid)
cause
Salmonella typhi and Salmonella paratyphi (types A, B & C) respectively
Enteric fever (typhoid/paratyphoid)
features
- initially: headache, fever, arthralgia
- rose spots on trunk
- constipation
- relative bradycardia
- abdo pain, distension
Enteric fever (typhoid/paratyphoid)
what kind of bacteria are Salmonella
aerobic, gram -ve rods
mnx for Clostridium difficile
1st line mild, moderate or severe infection is Vancomycin 125mg PO QDS
2nd line is Fidamomicin 200mg PO BD
resistent or life-threatening infection include using higher doses of Vancomycin or adding PO/IV Metronidazole
Tuberculosis
which bacteria is it caused by
mycobacterium tuberculosis
Tuberculosis
what kind of bacteria is mycobacterium tuberculosis
acid-fast bacillus (small rod shaped bac resistant to acids used in the staining procedure)
Tuberculosis
what stain is used
Zeihl-Neelsen stain
Tuberculosis
what colour does Zeihl-Neelsen stain turn mycobacterium tuberculosis
bright red against a blue background
patient coughing up sputum that grows acid-fast bacilli that stain red with Zeihl-Neelsen staining. what is the dx
TB
Tuberculosis
whom is TB more prevalent in?
- non-UK born pts
- immunocompromised
- those with close contacts with TB
Tuberculosis
what is MDR TB
multi-drug resistant TB
strains that are resistant to more than one drug, making them very difficult to treat
Tuberculosis
what makes TB bacteria difficult to culture and treat
very slow dividing with high oxygen demands
Tuberculosis
how is it spread
by inhaling saliva droplets from infected people
spreads through the lymphatics and blood
granulomas containing the bacteria form around the body
Tuberculosis
what is active TB
where there is active infection in various areas within the body
in majority of cases, the immune system is able to kill and clear the infection
Tuberculosis
what is latent TB
when the immune system encapsulates sites of infection and stop the progression of the diseases
Tuberculosis
what is secondary TB
when latent TB reactivates
Tuberculosis
what is miliary TB
when the immune system is unable to control the disease which causes a disseminated, severe disease
Tuberculosis
where is the most common site of TB infection and why
in the lungs where they get plenty of o2
Tuberculosis
what is extrapulmonary TB
where it infects other areas apart from the lungs
Tuberculosis
what is a cold abscess
a firm painless abscess caused by TB, usually in the neck
no inflammation, redness or pain
Tuberculosis
extrapulmonary TB areas
- lymph nodes
- Pleura
- CNS
- Pericardium
- GI
- GU
- Bones and joints
- Cutaneous TB affecting the skin
Tuberculosis
RFs (5)
- known contacts with active TB
- immigrants from areas of high TB prevalence
- close contacts from countries with a high rate of TB
- immunosuppressed
- homeless, drug users, alcoholics
Tuberculosis
what is the vaccine called
BCG vaccine
Tuberculosis
whom is the BCG vaccine offered to
patients that are at higher risk of contact with TB:
- Neonates born in areas of the UK with high rates of TB; relatives from countries with a high rate of TB; family history of TB
- Unvaccinated older children and young adults (< 35) who have close contact with TB
- Unvaccinated children or young adults that recently arrived from a country with a high rate of TB
- Healthcare workers
Tuberculosis
what are patients tested with prior to the BCG vaccine
Mantoux test: given the vaccine only if the test is negative
HIV and immunosuppression tested due to risks related to a live vaccine
Tuberculosis
what kind of vaccine is the BCG
live attenuated (weakened)
Tuberculosis
signs and symptoms
history of chronic, gradually worsening symptoms:
- lethargy, fever, night sweats, weight loss, lymphadenopathy
- cough with or without haemoptysis
- erythema nodosum
- spinal pain
Tuberculosis
what is Pott’s disease of the spine
spinal pain in spinal TB
Tuberculosis
what are the 2 tests for an immune response to TB caused by previous, latent or active TB
- Mantoux test
- interferon-gamma release assay
Tuberculosis
what investigations in patients where the active disease is suspected
CXR and cultures
Tuberculosis
what does a positive Mantoux test indicate
possible previous vaccination, latent or active TB
Tuberculosis
what is injected in the Mantoux test
tuberculin: a collection of TB proteins that have been isolated from the bacteria (not live bacteria)
Tuberculosis
what indicated a positive Mantoux test
an induration of the skin at the site of the injection of 5mm or more
Tuberculosis
what does interferon-gamma release assay test involve
taking sample of blood and mixing it with antigens from the TB bacteria
Tuberculosis
what indicates a positive interferon-gamma release test
If interferon-gamma is released from the white blood cells
In a person that has had previous contact with TB the white blood cells have become sensitised to those antigens and they will release interferon-gamma as part of an immune response
Tuberculosis
what is the interferon-gamma release assay used in
pts that do not have features of active TB but do have a positive Mantoux test
to confirm a diagnosis of latent TB
Tuberculosis
CXR findings in primary TB
- patchy consolidation
- pleural effusions
- hilar lymphadenopathy
Tuberculosis
CXR findings in reactivated TB
patchy or nodular consolidation with cavitation (gas filled spaces in the lungs) typically in the upper zones
Tuberculosis
CXR findings in Disseminated Miliary TB
“millet seeds” uniformly distributed throughout the lung fields
Tuberculosis
what are the ways to collect cultures
- sputum: may require bronchoscopy with lavage
- mycobacterium blood cultures
- lymph node aspiration or biopsy
Tuberculosis
why may nucleic acid amplification be used
It provides information about the bacteria faster than a traditional culture but is only used where having this information would affect treatment or they are at higher risk of developing complications (i.e. in HIV).
Tuberculosis
mnx of latent TB in otherwise healthy pts
nothing
Tuberculosis
mnx of latent TB in pts at risk of reactivation
either:
Isoniazid and rifampicin for 3 months
Isoniazid for 6 months
Tuberculosis
mnx of acute pulmonary TB
R – Rifampicin for 6 months
I – Isoniazid for 6 months
P – Pyrazinamide for 2 months
E – Ethambutol for 2 months
Tuberculosis
what should also be prescribed alongside isoniazid
pyridoxine (vit B6)
Tuberculosis
why should pyridoxine (vit B6) be prescribed alonside isoniazid
isoniazid causes peripheral neuropathy and vit B6 helps prevent this
Tuberculosis
whom should you inform of all suspected cases
PHE
Tuberculosis
SE’s of rifampicin
- red discolouration of secretions (urine + tears)
- potent inducer of CP450 enzymes so reduces the effects of drugs metabolised by the system e.g cocP
Tuberculosis
SE’s of Isoniazid
- peripheral neuropathy
Tuberculosis
SE’s of Pyrazinamide
- hyperuricaemia (high uric levels) –> gout
Tuberculosis
SE’s of ethambutol
- colour blindness
- reduced visual acuity
Tuberculosis
what is the common SE of Rifampicin, isoniazid and pyrazinamide
hepatotoxicity
HIV
which is the most common type
HIV-1
HIV-2 is rare outside West Africa
HIV
what kind of virus is it
RNA retrovirus
HIV
what does the virus destroy
CD4 T helper cells
HIV
how is it spread
- unprotected anal, vaginal or oral sex
- vertical transmission: mother to child via pregnancy, birth or breastfeeding
- Mucous membrane, blood or open wound exposure to infected blood or bodily fluids
HIV
AIDS-defining illnesses
- Kaposi’s sarcoma
- Pneumocystis jirovecii pneumonia (PCP)
- CMV infection
- Candidiasis (oesophageal or bronchial)
- Lymphomas
- TB
HIV
can antibody tests be negative for 3 months following exposure?
yes so repeat testing is necessary if an initial test is negative within 3 months of a potential exposure
HIV
do patients need to give consent for a test
yes, verbal consent is okay and should be documented
Patients no longer require formal counselling or education prior to a test.
HIV
what is the typical test used in hospitals to screen for HIV
antibody blood test
HIV
what test can give a positive result earlier in the infection compared with the antibody test
Testing for the p24 antigen
which checks directly for the specific HIV antigen in the blood
HIV
what test directly for the quantity of the HIV virus in the blood and gives a viral load
PCR testing for the HIV RNA levels
HIV
how is it monitored
- CD4 count
- viral load
HIV
what is the normal CD4 count range
500-1200 cells/mm3
HIV
what CD4 count is considered as end stage HIV / AIDS
<200 cells/mm3
HIV
what is the viral load
the number of copies of HIV RNA per ml of blood
HIV
what does ‘undetectable’ refer to
a viral load below the labs recordable range (usually 50 – 100 copies/ml)
HIV
recommended trx starting regime
2 NRTIs
(e.g. tenofovir and emtricitabine)
plus a third agent of: INI, NNRTI, PI
HIV
what are the Highly Active Anti-Retrovirus Therapy (HAART) Medication Classes
- Protease Inhibitors (PIs)
- Integrase Inhibitors (INIs)
- Nucleoside Reverse Transcriptase Inhibitors (NRTIs)
- Non-Nucleoside Reverse Transcriptase Inhibitors (NNRTIs)
- Entry Inhibitors (EIs)
HIV
what is given to pts with a CD4 < 200/mm3 and why
Prophylactic co-trimoxazole (Septrin)
to protect against pneumocystis
HIV
HIV infection increases the risk of developing CVD. How is this monitored
close monitoring of RFs and blood lipids and statins
HIV
why are yearly cervical smears required for women
HIV predisposes to developing cervical human papillomavirus (HPV) infection and cervical cancer
HIV
what vaccines should they have and not have
avoid live vaccines
They should be up to date with annual influenza, pneumococcal (every 5-10y), hep A and B, tetanus, diphtheria and polio
HIV
advise for reproductive health
- condoms
- dams for oral sex even when both partners are positive
- undetectable = untransmissible
HIV
advise with conceiving
- if undetectable viral load, unprotected sex and pregnancy may be considered
- safe to conceive with sperm washing and IVF
HIV
advise at birth
- vaginal birth considered if VL is undetectable
- c-section otherwise
HIV
what should newborns to HIV positive mothers receive
ART for 4 weeks after birth to reduce the risk of vertical transmission.
HIV
can positive HIV mothers breastfeed
considered if VL is undetectable but there may still be a risk of contracting HIV through breastfeeding
HIV
what can be given after exposure to HIV to reduce risk of transmission
Post exposure prophylaxis
HIV
what time period should post exposure prophylaxis be given
<72h of exposure
HIV
what is post exposure prophylaxis
combination of ART therapy for 28d:
- Truvada (emtricitabine / tenofovir)
- raltegravir
HIV
pt exposed to HIV. When should tests be done
immediately
then 3m after exposure
abstain from unprotected sexual activity in this time
Meningitis
what is the meninges
lining of the brain and spinal cord
Meningitis
what kind of bacteria is neisseria meningitidis
gram negative diplococcus aka meningococcus
Meningitis
what is meningococcal septicaemia
when the meningococcus bacterial infection is in the bloodstream
Meningitis
what does the non-blanching rash indicate
meningococcal septicaemia which has caused DIC + SC haemorrhages
Meningitis
what is meningococcal meningitis
when the bacteria is infecting the meninges and the cerebrospinal fluid around the brain and spinal cord
Meningitis
what are the most common causes of bacterial meningitis in children and adults
Neisseria meningitidis (meningococcus)
and Streptococcus pneumoniae (pneumococcus)
Meningitis
what is the most common cause in neonates
Group B Streptococcus (GBS).
Meningitis
typical sx
- fever
- neck stiffness
- vomiting
- headache
- photophobia
- altered consciousness
- seizures
Meningitis
where there is meningococcal septicaemia children can present with?
a non-blanching rash
Meningitis
how may neonates + babies present as
very non-specific:
- hypotonia
- poor feeding
- lethargy
- hypothermia
- bulging fontanelle
Meningitis
NICE recommends LP for children <1m presenting with?
a fever
Meningitis
NICE recommends LP for children 1-3m presenting with?
a fever and are unwell
Meningitis
NICE recommends LP for children <1y presenting with?
- unexplained fever
- and other features of serious illness
Meningitis
what are the 2 special test to look for meningeal irritation
- Kernigs Test
- Brudzinski’s Test
Meningitis
what is involved in Kernig’s test
- lie pt flat
- flex 1 hip + knee to 90 degrees
- slowly straighten knee whilst keeping hip flexed
Meningitis
+ve Kernig’s test explanation
slight stretch in the meninges created
so spinal pain or resistance if there is meningitis
Meningitis
what is involved in the Brudzinski’s test
- lie pt flat
- lift pt’s head + neck off bed and flex their chin to their chest
Meningitis
+ve Brudzinski test
pt involuntarily flex their hips + knees
Meningitis
mnx in community of child with suspected meningitis AND non blanching rash
urgent stat benzylpenicillin (IM/IV)
< 1 year – 300mg
1-9 years – 600mg
> 10 years + adults – 1200mg
admit
Meningitis
mnx in community of child with suspected meningitis AND non blanching rash
but allergic to penicillin
transfer should be the priority rather than other antibiotics.
Meningitis
inx in hospsital
should not delay trx:
- LP for CSF
- send bloods for meningococcal PCR
Meningitis
mnx in hospital for <3m
cefotaxime + amoxicillin
Meningitis
mnx in hopsital for >3m
ceftriaxone
Meningitis
why is amoxicillin added for <3m mnx
to cover listeria contracted during pregnancy from the mother
Meningitis
when should vancomycin be added to mnx
if there is a risk of penicillin resistant pneumococcal infection
e.g. recent foreign travel or prolonged abx exposure.
Meningitis
why are steroids given in bacterial meningitis
to reduce the frequency and severity of hearing loss and neurological damage.
Meningitis
medication if LP is suggestive of bacterial meningitis and >3m
ceftriaxone
+ dexamethasone QDS for 4d
Meningitis
is bacteria meningitis and meningococcal infection a notifiable disease
yes
Meningitis
who should be given post exposure prophylaxis
for people that have had close prolonged contact within the 7 days prior to the onset of the illness.
Meningitis
post exposure prophylaxis
single dose of ciprofloxacin ideally within 24 hours of the initial diagnosis of the contact
Meningitis
what is the most common cause of viral meningitis
HSV, enterovirus, VZV
Meningitis
which is milder, bacterial or viral
viral
Meningitis
mnx of viral
- often only supportive
- Aciclovir for suspected HSV meningitis
Meningitis
where does the spinal cord end
at L1-L2 vertebral level
Meningitis
where is the needle inserted for LP
L3-L4
Meningitis
LP samples are sent for what
bacterial culture, viral PCR, cell count, protein and glucose
Meningitis
CSF fluid for bacteria
- appearance
- protein
- glucose
- WCC
cloudy
high protein
low glucose
high neutrophils
Meningitis
CSF fluid for viral
- appearance
- protein
- glucose
- WCC
clear
mildly raised/normal protein
normal glucose
high lymphocytes
Meningitis
complications
- hearing loss
- seizures + epilepsy
- cognitive impairment + learning disability
- memory loss
- focal neuro deficits e.g. limb weakness or spasticity
Septic Arthritis
presentation
- Hot, red, swollen and painful joint
- Stiffness and reduced range of motion
- Systemic symptoms such as fever, lethargy and sepsis
Septic Arthritis
most common causative organism
staph aureus
other:
- neisseria gonorrhoea
- strep pyogenes
- haemophilus influenza
- e.coli
Septic Arthritis
Ddx
- gout
- pseudogout
- reactive arthritis
- hemarthrosis (bleeding into joint)
Septic Arthritis
inx
- joint aspiration
- send sample for gram staining, crystal microscopy, culture and antibiotic sensitivities
Septic Arthritis
what should be given until the sensitives are known
1st line: IV flucloxacillin + rifampicin
Septic Arthritis
abx if allergic to penicillin or MRSA or prosthetic joint
vancomycin + rifampicin
or clindamycin
Gastroenteritis
what is acute gastritis
inflammation of the stomach
N+V
Gastroenteritis
what is enteritis
inflammation of the intestines
diarrhoea
Gastroenteritis
what is gastroenteritis
inflammation all the way from the stomach to the intestines
Gastroenteritis
what is the most common
viral:
- rotavirus
- norovirus
- adenovirus
Gastroenteritis
what leads to HUS
shiga toxin produced from e.coli 0157
Gastroenteritis
what is a common cause of traveller’s diarrhoea
Campylobacter Jejuni
Gastroenteritis
how is Campylobacter Jejuni spread
- Raw or improperly cooked poultry
- Untreated water
- Unpasteurised milk
Gastroenteritis
when to consider abx for campylobacter jejuni
- after isolating the organism where patients have severe symptoms
- or HIV, HF
Gastroenteritis
popular abx choice for campylobacter jejuni
azithromycin or ciprofloxacin
Gastroenteritis
bloody diarrhoea. Drinking contaminated water, food and swimming pools. What is it
Shigella
Gastroenteritis
what can shigella produce and cause
shiga toxin so can cause HUS
Gastroenteritis
trx of severe cases
azithromycin or ciprofloxacin
Gastroenteritis
how is salmonella spread
- eating raw eggs or poultry and food contaminated with infected faeces of small animals
Gastroenteritis
sx of salmonella
- watery diarrhoea
- may be associated with mucus or blood
- abdo pain + vomiting
Gastroenteritis
leftover fried rice that has been left at room temperature.
what could it be
Bacillus Cereus
Gastroenteritis
typical course of bacillus cereus
- vomiting within 5h
- diarrhoea after 8h
- resolution within 24h
Gastroenteritis
bacillus cereus: what causes the vomiting within 5h
it produces a toxin called cereulide
Gastroenteritis
bacillus cereus: what causes the diarrhoea after 8h
When it arrives in the intestines it produces different toxins
Gastroenteritis
IVDU develops infective endocarditis. What could it be
most common: staph
bacillus cereus
Gastroenteritis
what kind of bacteria is bacillus cereus
gram positive rod
Gastroenteritis
what kind of bacteria is Yersinia Enterocolitica
gram-negative bacillus
Gastroenteritis
how is Yersinia Enterocolitica spread
- eating undercooked pork
- contamination with the urine or faeces of other mammal such as rat and rabbits
Gastroenteritis
who does yersinia most frequently affect
children
Gastroenteritis
presentation of Yersinia Enterocolitica
- watery or bloody diarrhoea
- abdo pain
- fever
- lymphadenopathy
Gastroenteritis
how long can sx of Yersinia Enterocolitica last
> 3w
Gastroenteritis
why can older children or adults present with right sided abdo pain in Yersinia Enterocolitica
mesenteric lymphadenitis (inflammation in the intestinal lymph nodes) and fever
Gastroenteritis
mnx of Yersinia Enterocolitica
abx only in severe cases (guided by stool culture + sensitivities)
Gastroenteritis
what is giardia lamblia
a type of microscopic parasite. It lives in the small intestines of mammals
It releases cysts in the stools of infected mammals
Gastroenteritis
trx of Giardiasis
metronidazole
Gastroenteritis
principles of mnx
- good hygiene
- Barrier nursing and rigorous infection control
- MC&S of faeces
- fluid challenge
- Slowly introduce a light diet in small quantities once oral intake is tolerated again
- stay off work or school for 48h after symptoms have completely resolved
Gastroenteritis
should you give loperamide or metoclopramide
generally not recommended but may be useful for mild to moderate symptoms
Gastroenteritis
post-gastroenteritis complications
- Lactose intolerance
- IBD
- Reactive arthritis
- Guillain–Barré syndrome
Tetanus
what is it caused by
the tetanospasmin exotoxin released from Clostridium tetani
Tetanus spores are present in soil and may be introduced into the body from a wound
Tetanus
features
- prodrome fever, lethargy, headache
- trismus (lockjaw)
- risus sardonicus
- opisthotonus (arched back, hyperextended neck)
- spasms (e.g. dysphagia)
Tetanus
mnx
- supportive: ventilatory support, muscle relaxants
- IM human tetanus Ig for high-risk wounds (e.g. compound fractures, delayed surgical intervention, significant degree of devitalised tissue)
- metronidazole
Give tetanus Ig for immediate protection regardless of immunization history, and if this is not up-to-date (or patient is immunocompromised) give additional booster doses of vaccine as well.
what does a positive tourniquet test indicate
dengue fever
hiker with swelling of knee, then flu like illness and now facial nerve palsy. What is it
lyme disease
what is the most common cause of leg cellulitis
strep pyogenes
