MICROBIOLOGY Chris Keil – F2

You are not alone Are there strong/powerful antibiotics? A lot of testing is with chromatography – the future will be genetic Apologies for pronunciation/mnemonics Cover gram positive/negatives and TB/quiz if time

REferences For treatment – BNF guidelines Microbiology and ID the basics – classification/treatment/everything you need to know When you are an FY1 – microbiology guidelines I won’t giving out the powerpoint – use the microbiology pdf – I will email this!

Shapes – draw each one with your hand COCCI BACILLI VIBRIO SPIROCHAETE

COCCI – ANY GENERALLY ROUND SHAPED BACETERIA

Bacilli – rod shaped

Vibrio – curved red/comma shaped – “VIBRONS” https://www.youtube.com/watch?v=4TWRFF79YsM

SPIROCHAETE - spirals

Why do I need to know about staining? Is it clinically relevant for working as an FY1? It comes up in exams The future will be genetic testing – the culture will be important for growth but less so in identification and sensitivities Help you navigate the branches of different bacteria

Different tests You should be aware of… 2 types of staining 2 types of agar 1 type of grouping

Gram staining – 2 broad groups + poorly staining Named after Hans Christian Gram Why do Gram staining? How many ways are there to slice a cake? POSITIVE – PURPLE NEGATIVE - RED

Gram Positive Gram Negative Other

Another type of staining Ziehl Neelsen Staining USED FOR MYCOBACTERIA THEY ARE ACID FAST – PINK/RED What does acid fast mean? THIS MEANS THAT THEY RESIST ACID DE-COLOURISATION PROCEDURES

Specific tests Gram Positive

CATALASE TESTS Gram positive cocci TELLS YOU THE DIFFERENCE BETWEEN: STAPHYLOCOCCI STREPTOCOCCI/ENTEROCOCCI staphylococci use catalase to protect against hydrogen peroxide – reaction you see bubbles – catalase positive if not present there is no reaction – catalase negative https://www.youtube.com/watch?v=K3-BMFHrsVg 23 seconds

Gram Positive Cocci Staphylococcus Strep/enterococcus

Coagulase positive Staphylococcus Used to differentiate between: Staphylococcus aureus Other Staphylococci COAGULASE is an enzyme that causes coagulation – fibrin to clot BACTERIA + PLASMA = CLOT - STAPH AUREUS – coagulase positive BACTERIA + PLASMA = NO CLOT – OTHER STAPH SPEICES – coagulase negative https://www.youtube.com/watch?v=IUIIDPCIvAE 1 minute 6 seconds

Staphylococcus S. Aureus Other Staphylococci

Oxidase test Identifies bacteria that are oxidase positive – produce cytochrome oxidase Pseudomonas Neisseria POSITIVE TEST RESULT – BLACK/PURPLE COLOUR NEGATIVE TEST RESULT – NO COLOUR CHANGE https://www.youtube.com/watch?v=d4PkuRtGfFo 25 seconds

Alpha haemolytic strep Optochin test Differentiates: Streptococcus pneumoniae – what type of cocci… Diplococci in chains From other alpha haemolytic streptococci Clear zone of lysis – strep. pneumoniae Alpha haemolytic strep

Agars

Blood agar Streptococci Differentiates Alpha haemolytic streptococci Beta haemolytic streptococci Alpha – green pigment Beta – clear zones of lysis Non-haemolytic – no change Streptococci

Macconkey agar – bile salts, lactose, ph indicator Enterobacteria/bacilli Bile salts only permit the growth of enteric bacteria Lactose fermentation causes an acidic environment – red/pink colour change with the indicator Red/pink colony – E Coli, Klebsiella Clear colony – Salmonella, Shigella, Pseudomonas

Lancefield grouping Differeniates beta haemolytic streptococci by detecting surface antigens: Lots of groups Group A Strep – pyogenes Group B Strep - neonates

Toxins Exotoxin – secreted by bacteria (MAINLY GRAM POSITIVE) – specific actions – like paralysis with botulinum toxin Endotoxin – released when bacteria is damaged, less specific action – septic shock

Gram positive Sexy Streptococcus spp Students Staphylococcal spp Can Corynebacterium spp ------- AEROBIC Diphtheria Look Listeria spp Listeria monocytogenes – non-pasteurised/those with contact with animals – farmers/vets! Bad Bacillus spp. – go to which type of restaurant Anthracis Cereus – reheated rice – in exams – Chinese restaurant Come morning Clostridium spp. ------ANAEROBIC

GRAM negative Cocci Neisseria Moraxella catarrhalis – which condition? Meningitidis – what type of cocci? Diplococci Gonorrhoea Moraxella catarrhalis – which condition? COPD

Gram negative bacilli ANAEROBES Bacteroides fragilis – causes… 90% of anaerobic peritoneal infections All the others are aerobes

Gram negative bacteria – aerobic bacilli Division by growth requirements MacConkey agar – lactose fermenters - ?properties E coli – causes gastroenteritis/UTI Klebsiella – causes Pneumonia/UTI Non lactose fermenters – MacConkey pale Salmonella – causes Typhoid, diarrhoea Shigella – causes diarrhoea in MSM (dysentery) Proteus – causes UTI

Gram negative aerobic bacteria - other Pseudomonas Aeroginosa – causes COPD and cystic fibrosis Nosocomial infections Vibro cholerae – where? 4 star rating on trip advisor

Other gram negative aerobic bacilli Fastidious growth requirements – complex Haemophilus Influenza – Harry Potter (IECOPD) Bordatella pertussis – Bought (Whooping cough) Legionella pneumophilia – Lots of (Legionella – hotels/air conditioning) Brucella – Big (Brucellosis – unpasteurised milk) Campylobacter – Cookies for (diarrhoea/GBS) Helicobacter Pylori – Hagrid (ulcers)

Other – poorly gram staining • Chlamydia spp. - CRUNCHY Psittaci – birds Trachomatis - chlamydia • Coxiella spp. - CARROTS Q fever • Mycobacteria spp. - MAKE TB, leprae • Treponema spp. – THE spirochaete - syphillis • Borrelia spp. - BEST Lyme disease • Leptospira spp. - LIGHT leptospirosis (water and livestock –farmer) • Mycoplasma spp. – MEAL FOR mycoplasma pneumoniae • Rickettsia spp. - RABBITS typhus (not typhoid!) spread by ticks

Tuberculosis 1/3 of the world’s population is thought to be infected with TB!!! Treatment – 4 antibiotics - RIPE Rifampicin - RED urine, hepatotoxicity Isoniazid – peripheral neuropathy – N for neuropathy Pyrizinamide - hepatotoxicity Ethambutol – ocular/EYE toxicity

Urinary tract - UTI Most common causative organism… E Coli Other causative organisms Proteus Klebsiella First line Trimethoprim/nitrofurantoin Or amoxicillin

Pyelonephritis Most common causative organism: E Coli Other causative organism Enterococcus faecalis Treatment Use cefuroxime or quinolone (floxacin – ciprofloxacin) Gentamicin

Prostatitis Most common causative organism E Coli But also Proteus Mirabilis Klebsiella Antibiotic Quinolones (ciprofloxacin)

SKIN - Impetigo Most common organism S Aureus Treatment Fusidic acid

CEllulitis Common organism S Aureus Management Flucloxacillin

RESPIRATORY - PNEUMONIA Most common cause Strep Pneumonia Other causes H Influenzae Atypicals – Coxiella, Chlamydophilia, Mycoplasma, Leigionella Management – depends on severity calculated using the CURB65 https://www.mdcalc.com/curb-65-score-pneumonia-severity

CAP/HAP CAP Low severity Amoxicillin Moderate High severity Benzylpenicillin + clarithromycin (why clarithromycin?) HAP – broad spectrum Co-amoxiclav – if early onset (less than 5 days into admission) Tazoin – if late onset (more than 5 days)

MSK - Osteomyelitis Common organism S Aureus Other Enterocbacter Streptococcus Bonus point – if sickle cell anaemia Salmonella Management Flucloxacillin

Septic arthritis Common organism S Aureus Other Streptococci Neisseria – in sexually active young adults Management Flucloxacillin

Eye Common organism S Aureus Other causes Streptococci Haemophilus Treatment Chloramphenicol

GASTRO infections – C Diff Treatment Metronidazole – use in situations where anaerobic bacteria are suspected

CNS - meningitis Treatment depends on causative organism 2 most common Neisseria Meningitidis Streptococcus Pneumoniae When unknown 3 months -50 years Cefotaxime Over 50 years Cefotaxime and amoxicillin

Other typical exam characteristics Listeria monocytogenes – causing listerosis (CNS infections and sepsis in immunocompromised) - Grows in hot or cold temperatures Cold – spread by PO route and growth not prevented by refrigeration Cholera causes what type of diarrhoea Rice water Which infection causes bovine cough Croup Which infection causes paroxysmal coughing Whooping cough

Other typical exam characteristics White or grey discharge/fishy smell Bacterial vaginosis – itching is uncommon Yellow, green, frothy and itchy Trichomonas

Questions