1 -4 Revision Flashcards
What are the 6 signs of sepsis?
Slurred speech Extreme shivering or muscle pain Passing no urine Severe breathlessness I feel like i might die Skin mottled/discoloured
What is sepsis?
A life threatening organ dysfunction due to dysregulated host response to infection.
What is the Sepsis 6 bundle?
- Give O2
- Take blood culture
- Give IV antibiotics
- Give fluid
- Measure lactate
- Measure urine output
How can sepsis be recognised early?
Raised EWS
What things are recognised as ‘red flags’ for sepsis?
RR > 25/min
SBP <91 mmHg
HR > 130/ min
How does sepsis lead to organ ischaemia?
Cytokines initiate the production of thrombin, promoting coagulation. Microvasculature thrombosis leads to organ ischeamia, dysfunction and failure.
What bacteria are most likely to cause sepsis?
Gram negative bacteria with potent LPS endotoxin
What antibiotic is commonly used to treat gram -ve sepsis?
Gentamicin
What type of antibiotic is gentamicin?
Aminoglyceride
How would you identify haemophilis influenza on a gram stain?
Gram negative
Pleomorphic - coccobacili to long filaments
Where is h.influenzae a commensal in the body?
Upper respiratory tract
How is H.influenzae spread?
Respiratory droplets
What can infection haemophilis influenzae cause in infants and young children?
Meningitis
What virulence factors does H.influenzae possess?
IgA protease that degrades IgA and allows colonisation of URT mucosa.
What antibiotic would you used to treat H. Influenzae?
Amoxicillin
How can H.influenzae infections be categorised?
Disseminated - via blood stream
Contiguous spread - site of colonisation in resp tract
What contagious spread infections can H.influenzae cause?
Sinusitis
Otitis media
Bronchopneumonia
What disseminated infections can H. influenzae cause?
** Bacterial meningitis mainly
Epiglottitis
Septic arthritis
How would you recognise E.coli on a gram stain?
Gram negative rod
Where is E.coli found in the body?
Normal flora in the colon
What virulence factors does E.coli have?
- Pili or fimbriae - adherence
- Generates energy by reducing nitrates to nitrites
- LPS
- Catalase-positive
How can a urine dipstick help to diagnose UTI caused by E.coli?
Nitrites positive - gram +ve uropathogens are nitrites negative.
How are E.coli UTI infections treated?
Trimethoprim
What is the mechanism of infection for E.coli?
- Movement to sterile body site
- Facal/oral route, from contaminated food and water
What extra intestinal diseases can E.coli cause?
UTI
Neonatal meningitis
Sepsis, Pneumonia, Shock
What are the presenting signs of cellulitis?
Rubor, Calor, Dolor, Tumor, Fever
What patient factors increase risk of cellulitis?
Elderly
Skin breaks - wounds, catheters
Compromised immune function
How would you recognise staph aureus on a gram stain?
Gram +ve (purple) cocci clusters
What antibiotic is used to treat skin and soft tissue staph.aureus infections?
Flucloxacillin
How would you recognise neisseria meningitidis on a gram stain?
Gram negative, diplococcus
Where does neisseria meningitis exist as a commensal in carriers?
Nasopharyngeal mucosa
What virulence factors does Neisseria meningiditis have?
- Pili - aid attachment
- Polysaccharide capsule
- LOS released during autolysis -> toxic endotoxin which can cause sepsis
What is the mode of transmission for Neisseria meningitidis?
Inhalation of respiratory droplets
How would a patient with meningitis present?
Severe headache
Rigid neck
Sensitivity to light
Petechial rash -non blanching
How would you treat meningitis caused by neisseria meningitis?
Ceftriaxone - beta lactam which is less susceptible to beta lactamases and accesses the CSF
What type of antibacterial is ceftriaxone?
Cephalosporin beta lactam
Which patients are more at risk of neisseria meningitidis infection?
Young, previously well patients
Smokers
Recent viral infection
Complement deficiency
How would you recognise strep pneumonia on a gram stain?
Gram positive, lancet-shaped cocci
Can be in pairs or chains
What 2 enzyme exotoxins are released from strep pneumoniae?
Autolysin
Pneumolysin
What do autolysin and pneumolysin do?
Autolysin causes cell wall lysis and the release of intracellular exotoxin pneumolysin which attacks cell membrane.
What bacteria is the most common cause of community-acquired pneumonia?
Strep. pneumonia
What other infections does strep.pneumonia cause?
Otitis media
Meningitis
Bacteraemia/sepsis
How would you treat mild and severe strep.pneumonia infections?
Beta lactam - amoxicillin
Co-amoxiclav if severe
What are staph aureus virulence factors?
- Cell wall - protein A, fibrinonectin-binding protein
- Superantigen exotoxins - toxic shock
- Cytlytic exotoxins - hemolysins
- Enzymes - coagulase, hyaluronidase, catalase
- Slime production
How does MRSA develop resistance to beta-lactam antibiotics?
Acquires modified PBP - PBP2a which has low affinity for all beta lactate antibiotics
What infection does epstein-barr virus cause?
Infectious mononucleosis (glandular fever)
What age group is infectious mononucleosis most common in?
15-19 year olds
What is the classic triad of symptoms associated with glandular fever?
Fever
Pharyngitis
Lymphadenopathy
Others - rash, jaundice
What is the structure of EBV?
Enveloped dsDNA virus
What is the initial site of EBV infection?
Oropharyngeal epithelium
How is EBV transmitted?
Saliva
What malignancies is EBV infection associated with?
Burkitt lymphoma
Nasopharyngeal carcinoma
Which cells does EBV infect?
B cells
When would you use chocolate agar?
To grow Haemophilus influenza as it will only grow if blood cells are lysed
What is the best way to diagnose a virus?
PCR
What is the MOA of trimethoprim?
Inhibits folic acid synthesis by inhibiting bacterial dihydrofolate reductase
What are the 4 P’s of infection control?
Place
Pathogen
Patient
Practice
What neisseria virulence factor is part of the vaccine and protects against some, but not all serogroups?
Capsule
For some serogroups, the capsule is antigenic but for others (B) the capsule does not trigger a good response.
Which response is likely to be activated by the flu virus?
Cytotoxic T lymphocytes
TH1 T cells
Antibodies
What feature of staph epidermidis enables it to cause infections on surfaces?
Produces slime that facilitates adherence to prosthetic surfaces such as catheters
Are fungi larger or small than bacteria?
Fungi are larger than bacteria.
Bacteria are larger than viruses.
Where would you take a swab to check if a patient is an MRSA carrier?
Nose swab - MRSA colonises the nose
What characteristic of clostridium allows it to survive outside the host for long periods?
Spore formation - dormant cell, resistant to heat, UV light and chemical agents
What is acute HIV infection characterised by?
A flu-like illness with a mild rash
Which blood cell would you expect to be raised in a viral infection?
T lymphocytes
Which blood cell would you expect to be raised in a bacterial infection?
Neutrophil
What is known as the ‘winter vomiting bug’?
Norovirus
What is the endotoxin of neisseria meningitidis?
LPS on the outer membrane
What bacteria is metronidazole active against?
Anaerobic bacteria - c.diff
What 2 toxins does C.difficule produce?
Toxin A - enterotoxin that produces excessive fluid secretion and inflammation of lining of bowel wall
Toxin B - cytotoxin that affects protein synthesis in cells
What gram negative bacilli is present in the colon?
Escherichia coli
What personal protection methods can be used when dealing with patients with infections?
Wear gloves
Wear apron
Wash hands before and after consultation
Wash stethoscope
List 4 causes of community-aquired pneumonia.
Strep pneumoniae
Haemiphilus influenzae
Influenza
Staph aureus
What bedside tests can be done to check for UTI’s?
Dipstick
Nitrites - some gram negative bacteria reduce nitrates to nitrites
