D and M of infections

Gram positive stains gram stain?

Purple/blue

Gram negative stains Gram stain

pink/red cell wall does not retain stain

Do atypicals stain?

No

Bacilli

rods

cocci

seed (round)

Gram positive cocci

Staphylococci Streptococci, Enterococci

Gram positive rod?

Clostridia (anaerobe),

Gram negative cocci?

Neisseria meningitidis, Neisseria gonorrhoea

Gram negative rods

E. Coli, Klebsiella, Enterobacter, Salmonella, Pseudomonas, Haemophilus, Helicobacter

Atypical

Do not stain

Atypical organisms?

Chlamydia no peptidoglycan in cell wall, Mycoplasma lacks cell wall, Mycobacteria no peptidoglycan

Other considerations for diagnosis and management?

Intracellular pathogens, blood supply, abscesses, properties of agent, MIC of organism

Diagnosis of Infection

Fell unwell, raised white blood cell count, temperature, Appearance, swelling inflammation, heat redness, SSI, could sample or do diagnostics

Managing community acquired pneumonia?

CURB-65

0-1 home treatment

2 → Consider unsupervised hospital treatment

3 → manage in hospital as severe pneumonia

How quickly do you need antibiotics in sepsis

Within the hour, broad then focus, IV fluids, Oxygen

What are the main factors that influence antibiotic choice?

Diagnosis and likely pathogen, Severity of infection, Local guidelines/policy, Allergy/intolerance

What do you need to decide when choosing antibiotics?

Agents, dose, route, duration/review date

What is Empirical therapy?

Clinical diagnosis of likely infection without microbiological information with best guess antibiotic

What is empirical therapy an example of?

Evidence based practice

What is empirical therapy based off?

Underlying knowledge of bacteria and antibiotics, Research and evidence

Adaptation of evidence to local resistance patterns/ national drivers, Run through the mangle of local/expert opinion and pragmatism

CAP symptoms and markers?

Focal signs on chest exam, new shadowing on x-ray, no sore throat or runny nose, cough, chest pain, dyspnoea

CAP antibiotics?

Amoxicillin if mild Doxycycline if MRSA or allergy for all PO only, Clarithromycin is moderate, Co-amoxiclav if severe

UTI symptoms?

Dysuria, frequency, haematuria

How do you diagnose UTI?

Dipstick, clinical symptoms, urine culture

What counts as complicated UTI?

**male, pregnant, neutropenic, Upper UT symptoms, Recurrent**

Pros of Empirical therapy?

Provides reproducible guide to practice, Should be effective in majority of cases, Junior doctors use religiously

Cons of Empirical therapy?

Only a guess, may not cover rarer causes of infection, causative organism might be resistant, tends to broader spectrum → side effects

What does MC&S stand for?

microscopy, culture and sensitivity

What would MC&S sample?

* Swab (skin, wound, mucosal membrane), Blood sample, Sputum, Tissue, Aspirate, Pus, Bronchial lavage

Stepwise provision of info?

1. Culture positive (something is growing)
2. Identification (we know what it is)
3. Sensitivities (we know what to treat it with)

What are Microscopy investigations?

Gram stain, cell morphology (shape) / clumping

What are culture and diagnosis investigations?

Selective culture conditions, colony morphology, immunoassay, PCR (DNA)

What are Identification investigations?

Biochemical ID tests

Antibiotic sensitivity investigations?

Disc diffusion → zone of inhibition

Broth dilution → MIC

Pros MC&S guided therapy?

Know what is causing infection, know about resistance, should be successful, targeted, narrower spectrum, less chance of nosocomial infection

Cons MC&S guided therapy?

Contamination or colonisation → could be wrong

Might be mixed causes all organisms may not be know

What do need to consider with co-pathologies?

Excretion, change in dose, nephrotoxicity, Hepatic impairment, Epilepsy

Allergic reactions?

Hypersensitivity Type 1 → IgE, Type 2/3 no IgE

Ciprofloxacin interactions?

P450 inhibitor → reduces metabolism of other drugs, increased plasma levels

Rifampicin interactions

P450 inducer → Increases metabolism of other drugs, reduced plasma levels

Macrolides interactions

CYP3A4 inhibitor → reduced metabolism of other drug, risk of myopathy with steroid so they tend to be stopped for duration

Linezolid interactions?

Monoamine oxidase inhibitors

Effect on Oral contraceptives?

Concern with inducers, Oestrogen undergoes EHC → less recirculates meaning inadequate suppression of ovulation

What is monitoring therapy?

Stopping, Step down, escalation → for side effects as well

How to monitor effectiveness of treatment?

Physical symptoms, physiological parameters → Blood pressure, temperature, Infective markers → CRP, FBC, Radiology

Drugs that need therapeutic monitoring?

Vancomycin, Gentamicin, Teicoplanin

When are IV antibiotics reviewed?

48hrs

What standards do patients have to be to switch from IV to Oral?

Temp under 37.5 C for 24 hrs, condition improving, signs and symptoms of infection improving, decreased ESR, CRP, WBC, No absorption problems, Suitable oral alternative, not known to be suffering from high risk infection?

High risk infections?

S. aureus, Pseudomonas, Severe gangrene, if chemotherapy is involved, implants, Meningitis, Intracranial abscess, Mediastinitis, Endocarditis, Cystic Fibrosis involved, Inadequately drained abscess or empyema, Pancreatitis, Bone and joint, Serve cellulitis, Diabetic foot interaction, MRSA, C.diff

When should you review antibiotic focus?

48-72 hrs