MICROBIOLOGY Flashcards
Doxycycline mechanism and is used for..
Inhibits bacterial protein synthesis…. Broad gram +ve’s. Chest infections
Cephalosporins.. mechanism, used for, examples
Beta lactam - has best resistance to beta lactamases. Good bactericide. Used when want to kill bacteria quickly. Endocarditis, meningitis.
Cefotaxime
Macrolide.. mechanism, used for, examples..
Inhibits protein synthesis, used for gram positives and atypical pneumonia pathogens, clarithromycin and erythromycin
Metranidazole… mechanism, used for…
Inhibits nucelic acid synthesis, can only do this in anaerobic bacteria, eg bacteroides, C Diff (although may need something like Vancomycin for C Diff instead)
What antibiotic combination would you give for a pt with suspected aerobic (eg E coli) and anaerobic (eg Bacteroides) infection of peritoneum (eg from appendix rupture)
Beta lactam to cover aerobe - eg. penicillin (if not allergic), co-amoxiclav, cephalosporin (if concerned about resistance) + metronidazole to cover anaerobes
Is E coli aerobic or anerobic
Aerobic - t/f do not treat with metronidazole
Is C Diff aerobic or anerobic - how would this guide antibiotics?
Its anerobic so could you metronidazole. But something like IV vancomyosin could also be used.
Empirical antibiotics for suspected bacterial meningitis
Cephalosporin - cefotaxime
Empirical antibiotics for strep pnemoniae
Amoxicillin (beta lactam - gram +ve)
Empirical antibiotics for staph aureus (no resistant) and resistant; penicillin allergy
Not resistant - flucloxicillin
?Resistance - co-amoxiclav, cephalosporin
Penicillin allergy - vancomysin
Empirical antibiotics for cellulitis and why
Probably gram positive stap or strep.
- If no penicillin allergy - start on beta lactam. Use something that covers resistance until you know more - eg co-amoxiclav (if it is sensitive to just penicillin, can use this later). Bactericide - will kill bacteria.
- clindomyacin (protein synthesis inhibitor) - bacteriostatic - stops bacteria from making endotoxins - so will neutralise endotoxin release from active bacteria
Empirical antibiotics from UTI and why
Gram -ve = trimethoprim, nitrofuratoin
Snail worm infection is called…
Schistosomiasis
Define protozoa
Single cell eukaryotic organism.
Have parasitic and symbiotic relationships
List 5 important infectious protozoa
Giardia - treat w/ metronidazole. No blood. Flatulence & cramping.
Cryptosporidium (water) - No blood. D&V. No cramping. fluids & antiemetic
Amoeba - amoebic dysentery (blood) and liver abscess - metronidozole.
Toxoplasmosis - would see this is immunocomp - HIV
Malaria - treat depending on resistence, quiniolones
What antibiotics are commonly used for parasitic infections
Metronidazole
Treatment of cryptosporidium infection
IV fluids & anti-emetics
What is the most common tropical disease in UK
What are the symptoms & signs, how would you check for it
Malaria
Fever, sweats, chills, diarrhoea, nausea, vomitting, headache, myaglia, fatigue
Signs: jaundice, anaemia, hepatosplenomegaly, black water fever - dark urine
What antibiotics cause C Diff
Antibiotics “rule of C’s” Clindamycin Ciprofloxacin (Quinolones) Co-amoxiclav (Penicillins) Cephalosporins (especially 2nd and 3rd generation)
List some risk factors for developing C diff
Age If patient is on PPI (can increase risk) Long hospital stay Immunocompromised Nasal tube, GI surgery
What is the treatment for C Diff
Metrondazole
ORAL Vancomycin
Rifampicin/rifaximin
Stool transplant
What is the commonest site of infection
Respiratory tract
What is the characteristic presentation of chickenpox rash
Central distribution - likes warm places, so usually torso under skin, not peripheral where it is cooler
Starts as macule (not raised - could be anything at this stage) - then papule (raised) - vesicle (fluid)- pustule (pus) - enlarges - crusts over and heals
macule - papule - vesicle - pustule
What is the infectious period of chickenpox
Infectious from 2 days before rash presents till all pustules have crusted over
What is the most important complication of primary varicella virus (chickenpox) infection and which patient groups should you be worried about with this complication
Pneumonia
Pregnant women
Compromised
*NB this is only a complication for those who have never been exposed as it is to do with the virus being in the respiratory tract
Systemic symptoms of respiratory infection are most commonly associated with which conditions
Pneumonia and Influenza A
Examples: myalgia (muscle aches), arthralgia (joint aches)
Sore throat and headache is associated with which respiratory pathogen
Mycoplasma pneumonia - really bad cold with sore throat, headache/ congestion - occurs in epidemics
If you have a patient with presentation of bacterial pharyngitis, what pathogens do you need to consider and rule out
Strep pyogenes - scarlet -> rheumatic fever
Mycoplasma pneumoniae - headache/ congestion
Neisseria gonorrhoea
Corynebacteria Diptheria
Lemierres disease - IJV
What are the complications of bacterial sinusitis
Brain abscess, Sinus vein thrombosis, ortibal cellulitis
How can you tell if sinusitis is viral or bacterial
Bacterial signs:
Unilateral facial pain
Pus discharge from nose (purulent discharge)
>10 days of fever
acute onset with complications - eg swelling and signs on vein thombosis
What are the phases of whooping cough - what is the pathogen
Incubation 7-10 (5-21d)
Catarrhal phase 1-2 weeks; rhinorrhoea, conjunctivitis, low-grade fever and at end of phase lymphocytosis
Paroxysmal phase 1-6 weeks coughing spasms ,inspiratory ‘whoop’ post-ptussive vomitting, cough>14d
Convalescent phase
List some paraneoplastic signs on lung cancer
Finger clubbing Hypertrophic pulmonary osteoarthropathy Hypercalcaemia Weight loss Anorexia Peripheral neuropathy (muscle weakness of the limbs)
Describe the causes and pathology of lung cancer
Causes: Smoking Asbestos Radon Chromium Coal products
Pathology:
Small cell lung cancer - neuroendocrine cells (15%)
Non-small cell lung cancer (80%)
-squamous cell carcinoma (squamous hyperplasia of columnar cells) (20%)
-adenocarcinoma (columnar cells) (40%)
-large cell - poorly differentiated
-NOS - not any of the above. - cant be identified
Describe how lung cancer presents
Often asymptomatic until stage 3 or 4 - when it has metastasised Symptoms can be local: Cough Chest pain Haemoptysis Hoarse voice
Symptoms can be from metastises: Bone pain Brain - seizures, neurological deficit Lymph - adenopathy, swelling Adrenal Liver - hepatic pain; abnominal pain
Which stages of lung cancer are resectable
Stages 1 and 2
Before it metastises
Outcomes declines the more tumours and nodes there are involved, even if still only local invasion
Outline the survival rates (roughly) for the different stages of lung cancer
Survival at 5 years Stage 1: T1 - 60%; T2 - 40% Stage 2: T1, N1 - 30%; T3 - 20% Stage 3: 5-10% Stage 4: 1%
What stage does NSCLC most often present at
70% of presentations are stage 3 or 4
What affects chemotherapy outcomes in NSCLC
Performance status - there is approximately a 20-30% benefit in survival at one year in those with performance status 0-1 vs 3. 0-1 with chemo = 35% survival at 1 year. 3 with chemo = <5% survival.
Performance status 4 + chemo = 0% survival at 1 year
Outline the treatment options for the different stages of NSCLC
Stages 1 & 2 = surgery & RTX. +/- chemo.
Stages 3 & 4 = palliative chemo, palliative care, chemo + RTX (palliative?)
What is the main difference in management / treatment options between NSCLC and SCLC
Some NSCLC will be eligible for surgery
SCLC - surgery is not an option.
Both have bad outcomes, but a low stage NSCLC probably has the best outcomes out of them all.
What investigations are required for a patient who you suspect might have lung cancer
Imaging:
CXR
CT
PET - be aware of false positive (infection etc) and negatives - some tumours don;t show up
Biopsy: Bronchoscopy Bronchoscopy +/- US guided biopsy percutaneous (CT guided) needle biopsy US guided aspirate or biopsy Surgical biopsy
Bloods: to look for signs of metastatic spread and damage being done to any organs, or to rule out other causes - infection etc
CT thorax/abdo, PET scan,
CT head, medistinoscopy, pleural aspiration,
What should be the focus of a history for a patient that you suspect may have lung cancer
1.Social & occupational history
-Do they smoke?
-Where do they live - Radon exposure?
-What is or was their job - asbestos, chromium exposure? Try to identify any risk factors of lung cancer.
2.Past medical history
-Have they previously had cancer?
-Think about breast, prostate, colorectal cancers that can metastasise to lung
3.Symptoms of metastatic spread
-any recent onset bone, joint pain?
-any weakness in muscles? - peripheral neuropathy?
-any swelling anywhere - lymph adenopathy?
-think about brain, bone, lymph, adrenal glands etc
4.Any paraneoplastic symptoms
Finger clubbing
Peripheral neuropathy etc
5.Performance status
-Ask the patient about their daily living - what are they able to manage?
What would you include in a differential for lung cancer
Pneumonia
Pulmonary embolism
Any other lung disease that can cause a cough or chest pain
GORD
What lung cancer has the best outcomes
Stage 1: T1 N0 M0 - 60-80% survival at 5 years
What serology profile would indicate that a patient does not have chronic hepatitis after an acute infection
Presence of Antibodies against Hep B surface antigen
+ No detectable levels of HepB surface antigen or cor antigen
What serology profile would indicate that a pt who has previously had an acute hep B infection has progressed to chronic
Detectable levels of Hep B surface antigen in bloods >6 months after acute infection
No antibodies against HepB surface antigen
