PMP201 Infection ISU

Definition: Minimal Inhibitory Concentration

Lowest drug concentration that prevents visible bacteria growth

Definition: Minimum bactericidal concentration

Lowest drug concentration that kills the pathogen

Definition: Bacteriostatic

Inhibits growth of bacteria (Without killing it)

Definition: Bactericidal

Kills bacteria

Broad Spectrum Antibiotics - When are they used

• Serious, unidentified infections

• Mixed infections

• Prophylactic Measures (E.g surgery)

Narrow Spectrum Antibiotics - When are they used

With identified pathogens

Ibuprofen for skin conditions? Y/N

NO - Linked with skin infection

Lab tests for antimicrobial Activity - Dilutions Susceptibility Test

• Determines Minimum Inhibitory Concentration AND Minimum Bactericidal Concentration

• A fixed number of bacteria exposed to serial dilutions of antibiotic liquid media

  • MIC = The lowest drug concentration that shows no turbidity(Growth)

  • Samples from tubes with no growth are then cultured to identify MBC

Lab Tests for antimicrobial activity - Disk Diffusion tests

• Dots of antibiotic placed around agar plate

• Bacteria allowed to grow

• Measurement of bacteria-free zones around antibiotics and compared to reference values corresponding to susceptibility and resistance

  • Wider zones = Bacteria more susceptible to the antibiotic

  • Narrower zones = Bacteria show resistance to the antibiotics

Lab Tests for antimicrobial activity - The Etest

• Bacteria are inoculated on agar plate

• E-test strips with a gradient of antibiotic concentration are placed on the plate

• After incubation, an elliptical zone of inhibition is formed around the strip

• The MIC is determined where the edge of bacterial growth intersects the antibiotic gradient on the strip

Classes of Antibiotics (Mechanisms of Action)

• Inhibition of cell wall synthesis

• Inhibition of protein synthesis

• Acting as antimetabolites

• Inhibition of nucleic acid synthesis (DNA or RNA synthesis)

• Generating reactive free radicals

Mechanism: Cell wall synthesis inhibiting antibiotics (β-Lactams)

β-Lactams bind to, and block, transpeptidases (PBP), blocking transpeptidation of peptidoglycan chains, inhibiting cell wall synthesis

Leads to cell lysis (Bactericidal effect)

β-Lactamases inactivate β-Lactams

Classes of Cell wall synthesis inhibiting antibiotics

• Penicillins (-illin)

• Cephalosporins (Cef-)

• Carbapenems (-penem)

• Monobactams (-nam)

Adverse Effects & Contraindications: Penicillins

Adverse Effects:

GI distress

Disrupt the gut flora —> causing diarrhea and nausea

CNS Toxicity

Flucloxacillin can cause hepatic disorders (Rare)

Contraindications:

Patients with history of hypersensitivity

Patients with hepatic impairment

Mechanism: Protein synthesis inhibiting antibiotics

Target bacterial ribosomes to block protein synthesis

—> stop bacterial growth (Bacteriostatic)

REMINDER: Ribosomes synthesis proteins from mRNA into chains of amino acids in 3 phases:

• Initiation (ribosome subunits assemble with the mRNA and first tRNA)

• Elongation (tRNAs recognise specific mRNA codons bringing specific amino acids. Ribosome links them into polypeptide chain)

• Termination (Completed polypeptide is released —> functional protein, ribosome disassembles

Different antibiotics target different steps

Mechanism: Antimetabolite antibiotics

Inhibit essential bacterial metabolic pathway

Bacteriostatic effect

Mechanism: Antibiotics that inhibit nucleic acid synthesis

Different antibiotics target different enzymes:

Fluoroquinolones target bacterial topoisomerases, essential for DNA replication

Rifamycins inhibit RNA polymerase, blocking gene transcription

Both have bactericidal effect

Groups of Antibiotics that generate Reactive Free Radicals

Metronidazole (-azole)

Nitrofurantoin

Mechanism: Antibiotics that generate Reactive Free Radicals

Metronidazole:

Generates free radicals in bacteria

Free radicals are toxic (ROS) and lead to DNA fragmentation —> Cell death

Nitrofurantoin:

Forms ROS that damage DNA and cell componenents

Used for Gram-ve in UTIs (E. Coli, Enterococcus, klebsiella) and Gram+ve

Tuberculosis (TB) - Sites and Forms

Sites

• Pulmonary TB - Lungs

• Extrapulmonary TB - Lymph nodes, bones, CNS, kidneys, etc.)

Forms

• Latent TB - Asymptomatic, non-infectious

• Active TB - Symptomatic, infectious

  • Features: Chronic cough, hemoptysis, fever, night sweats, weight loss

Tuberculosis - First Line Treatment, Newly Diagnised (RIPE)

RIPE (2 months)

R- Rifampicin

I- Isoniazid

P- Pyrazinamide

E- Ethambutol

RI (4 Months)

R- Rifampicin

I- Isoniazid

Cystitis (UTI) - Causes

• Wiping back to front

• Previous infection not clearing

• Uncontrollable Diabetes

• Sexual Intercourse

• Irritation from chemicals / toiletries

• Post-menopausal changes to vaginal lining

• Side effect of medication

Cystitis (UTI) - Symptoms

• Signs of impending attack - Itching or pricking in urethra

• More frequent and urgent desire to pass urine

• Can only pass few, burning drops of urine

• Bladder may not feel completely empty

• Cloudy and smelly urine

Cystitis - Red Flags

• Blood in urine (Haematuria)

• Vaginal Discharge

• Children

• Males

• Pregnant Females

• Post-menopausal women (Could be vaginal atrophy)

• Catheterized Patients

• Upper UTI symptoms (Back pain, systemic symptoms)

• Symptoms lasting longer than 2 days

• Recurring

• Failed Treatment

Cystitis - Management (Self & OTC)

Self-management:

• Avoid vaginal irritants

• Hydrate

• Empty bladder fully

• Wipe front to back

• Urinate after sex

OTC:

• Simple analgesia

• Alkalysing agents

  • Potassium citrate and sodium citrate

• Antibiotics (Available on CAS)

Cystitis - POM Treatment

1st Line:

Nitrofurantoin

100mg BD M/R

Common side effects: Colours urine yellow/Brown, GI side effects

OR

Trimethopim (NOT FOR PREGNANT PATIENTS)

200mg BD

Common side effects: Diarrhoea and vomiting, Electrolyte imbalance (K+), Headache, Skin reactions

Women: 3 Days

Men: 7 Days

Complicated Lower UTIs - What makes it?

• 65+

• Care home resident

• Recurrent UTI

• Recurrent Hospitalisation

• Unresolving symptoms

• Travel through high antimicrobial resistance areas

• Previous resistant UTI

In women:

• Renal impairment

• Abnormal urinary tract

• Poorly controlled diabetes

• Immunosuppression

In men:

• TECHNICALLY all male UTIs are complicated

DO NOT TREAT OTC

Complicated UTI - POM Management

1st line: (Same as regular UTI except 7 days for men and women)

Nitrofurantoin

100mg BD M/R

Common side effects: Colours urine yellow/Brown, GI side effects

OR

Trimethopim (NOT FOR PREGNANT PATIENTS)

200mg BD

Common side effects: Diarrhoea and vomiting, Electrolyte imbalance (K+), Headache, Skin reactions

2nd Line:

Pivmecillinam (Not suitable for penicillin allergies)

400mg TDS 7/7

Patients must be 40kg+

Risk of esophageal ulceration (Therefore must take with half glass of water and after a meal and not lying flat)

OR

Fosfomycin

3g (1 sachet) STAT, then repeat 3 days later

Dissolve sachet in water and take on empty stomach (2-3 hours before or after a meal, preferably bedtime after emptying bladder)

Pyelonephritis - What is it?

Upper UTI or kidney infection

When bacteria that cause cystitis travels from the bladder up to one or both kidneys

Pyelonephritis - Symptoms

Fever

Shivers

Nausea

Pain in lower back / side

Lower UTI symptoms

If severe - Treat in Hospital

Pyelonephritis - Management

1st line: Cefalexin (Risky for penicillin allergy, don’t give if directly sensitive)

1g PO TDS 7-10 Days

2nd Line: Co-trimoxazole

960mg PO BD 7-10 Days

OR

Ciprofloxacin

500mg PO BD 7 Days

Urosepsis - What is it? + Symptoms

When bacteria from a UTI moves into the bloodstream

Symptoms:

Increased heart and respiratory rate

Fever

Chills

Little to no urine output

Anxiety / impending doom

Dizziness, inability to focus, loss of conciousness

Organ failure and septic shock (Low BP, cyanosis, pale)

UTI symptoms

Urosepsis - Management

Blood and urine samples should be sent for culturing

Whilst waiting for results:

Treat the same as pyelonephritis

1st line: Cefalexin (Risky for penicillin allergy, don’t give if directly sensitive)

1g PO TDS 7-10 Days

2nd Line: Co-trimoxazole

960mg PO BD 7-10 Days

OR

Ciprofloxacin

500mg PO BD 7 Days

Sepsis - Red Flags

• New onset confusion

• >25 breaths per minute

• Needs oxygen therapy to maintain O2 >92%

• Systolic BP <90 mmHg (Or drop of >40 mmHg from normal)

• Raised heart rate >130bpm

• Not peeing for >18 hours

• Skin symptoms

  • Mottled or Ashen

  • Cyanosis

  • Non-blanching rash

• Impaired immunity

Seasonal Influenza - Symptoms

• Fever

• Exhaustion

• Headaches

• Congestion

• Coughing

• Aches and pains

Might also have

• Dry cough

• Sore throat

• Difficulty sleeping

• Loss of appetite

• Stomach pains

• Diarrhoea / N + V

Flu - Red Flag

• Pregnant Patient

• Very young or very old

• Chronic respiratory disease (Asthma, COPD etc.)

• Chronic heart disease

• Chronic renal or liver disease

• Chronic neurological conditions

• Diabetes mellitus

• Immunosuppressed

Flu - Diagnosis

Throat swabs, undergoes PCR in lab to identify strain

Flu - Treatment - Mild Infection

Will get better with time:

Drink plenty of fluid

Manage pain/headaches with simple analgesia

Manage fever with paracetamol

Flu - Treatment - Moderate infection

Tamiflu (Oseltamivir) - Type of neuraminidase inhibitor - antivral)

Start within 48 hours of symptoms onset

Minimum 5 days of treatment (BD Dosing)

Flu - Treatment - Severe infection

Relenza or Dectova (Zanamivir, type of neuraminidase inhibitor - antiviral)

BD dosing for 5-10 days

Start within 48 hours of symptoms

Inhaled powder (Via diskhaler) or IV infusion

Uncomplicated genital chlamydia - Definition

Infection of the urogenital tract, typically causes inflammation of the urethra in men and inflammation of the cervix and/or urethra in women

Asymptomatic in 70% of women and 50% of men

Diagnosis of chlamydia in MEN

A first-catch urine (FCU) specimen

Urethral swab can be an alternative

Diagnosis of chlamydia in WOMEN

A vulvo-vaginal or endocervical swab

OR a first-catch urine (FCU) sample

Chlamydia - symptoms (Women)

• Heavier periods

• Abdomen or pelvic pain

• Vaginal discharge

• Irregular periods

• Bleeding between periods

• Pain during urination

• Pain and bleeding during/after sex

Chlamydia - Symptoms (Men)

• Pain during urination

• Pain in the testicles

• Swelling of the testicles

• Burning or itching of the urethra

• White watery or cloudy discharge from penis

Chlamydia - Management

Non pregnant people aged 13+

Doxycycline 100mg BD 7/7

OR

Azithromycin 1g single dose, then 500mg OD 2/7 (Works for pregnancy)