Mersey Care NHS Trust Infection Control Link Practitioner Training Session September 26th 2012 Please put mobile phones on silent Remember E-mail all correspondence to email@example.com
Introduction to Medical Microbiology Mike Rothburn Infection Control Doctor Consultant Medical Microbiologist
Aims What is medical microbiology? Why is it relevant? Some important concepts. Basic classification of organisms. Classifying bacteria.
What is Medical Microbiology? “The study of microorganisms (including bacteria, viruses, fungi and parasites) which are of medical importance and are capable of causing diseases in human beings”
What is Medical Microbiology? What organisms cause infection? How they cause infection. How to treat them. How to prevent infection.
Why is it Important? Infection is one of the most important causes of mortality and morbidity in the population. Approximately 30% of hospital patients are on antibiotics at any one time 1 in 10 patients acquires an infection whilst in hospital.
A Few Concepts Normal Flora Contamination Colonisation Infection
Normal Flora Human beings are not microbiologically sterile. We are ALL covered with bacteria, fungi and some parasites. Skin, nose, mouth, gastrointestinal tract … ~109 bacteria per gram of faeces Each person carries more non-human cells on their body than their own
Normal Flora Why? Fulfil a range of useful functions (symbiotic in some cases). Prevent other, pathogenic bacteria from gaining a foothold: by taking up space competing for nutrients. In the gut they aid digestion & produce essential vitamins (folic acid & vitamin K). Can cause disease IF they get into the wrong site- e.g. perforated appendix.
Contamination Presence of an organism in a culture that was not in the sample when taken. e.g. a culture of blood contaminated with an organism from the skin sample contaminated in the lab
Colonisation Presence of an organism at a site but not causing a tissue reaction (inflammation), symptoms or disease. Could be normal flora Could be abnormal flora-such as after the patient has received antibiotics.
Infection Where organisms invade a body site and their multiplication initiates a tissue reaction producing symptoms/disease.
Classification of Organisms All living organisms are classified into: Kingdom Phyllum (family) Genus Species Organisms that can cause disease are many and varied and include: Viruses Bacteria Fungi Parasites
Relevance of Classification Different: Diseases Modes of transmission Treatment-e.g. antibiotics don’t cure viral infections
Viruses Small (50-300nm) Unable to replicate independently Invade host cells and use their cellular machinery to replicate Influenza, Chickenpox (varicella), Herpes, Rhinovirus, HIV/AIDS Often difficult to treat
Bacteria 500-800nm Capable of independent replication Cause of most infections seen in hospital Pneumonia, bacterial meningitis, cellulitis, UTI… Many different species Treated with antibiotics
Fungi Complex, large organisms Eukaryotes (as are humans!) Divided into yeasts & moulds Cause a range of diseases e.g.: Thrush Athletes foot Invasive & allergic aspergillosis Many diseases are opportunistic.
Parasites • A parasite is an organism that depends upon another organism, known as a host. • Parasites that remain on a host's body surface to feed are called ectoparasites, while those that live inside a host's body are called endoparasites • Endoparasitic infections are not very common in the UK • Travellers to more tropical parts of the world can return with endoparasitic infections.
Parasites Ectoparasites include : Ticks, fleas, lice, and mites Endoparasites: Two groups Single celled Protozoa such as : Amoebae (Dysentery) ,Plasmodium (Malaria) and Giardia. Helminthes: Larger multi-cellular organisms such as Tapeworms, roundworms and liver flukes
Classifying Bacteria Why bother? Different bacteria: Cause different diseases Are susceptible/resistant to different antibiotics Some bacteria are common normal flora whilst other closely related species are pathogens
Classifying Bacteria How? 1st into broad groups based on microscopic appearance Then divided into species based on a range of different properties-often biochemical reactions e.g. some may be able to metabolise a sugar that others cannot.
Gram Stain Method of differentiating bacteria. Can be either Gram +ve or Gram –ve depending on how they appear with the stain. Can then be further grouped based on shape (rod=long thin or coccus=round). Thus we end up with 4 combinations: G+ rod, G+ coccus, G- rod, G- coccus
Gram Stain STAIN the slide with crystal violet for 1-2 min. Flood slide with Gram's iodine for 1-2 min. Decolourise by washing the slide briefly with acetone (2-3 seconds). Stain with safranin counterstain for 2 min. View under microscope G+ve G-ve
Gram Stain Gives an initial idea of the possible identity of the organism. Can be done without growing the organism (i.e. rapid result) Thus can be done on pus, joint fluid, sputum, CSF 1st result available on blood cultures
Gram Stain Relevance of Gram reaction. Gram +ve and gram –ve organisms are susceptible to different groups of antibiotics. Cause different diseases Differ in their ability to survive in the environment-cleaning, infection control, outbreak management.
Sexually Transmitted Infections Margaret Fagan Health Adviser The Liverpool Centre for Sexual Health Department Genitourinary Medicine
Some Sexual Transmitted Infections….. Chlamydia Gonorrhoea Syphilis Hepatitis TV HPV HSV HIV NSU Crabs (Pubic Lice) Scabies Molluscum
Chlamydia – the concerns Up to 50% of men have no symptoms Up to 80% of females have no symptoms Highest prevalence is in 16 – 19 yrs old in women and 20 – 24 yrs old in men 1 in 10 under 25 year olds are Chlamydia positive
How Is Chlamydia Transmitted? Through unprotected sex (vaginal, oral, anal) Mother to baby Hand to eye transmission
Chlamydia complications PID (inflammation of the pelvis) Infertility Ectopic pregnancy Inflammation of testes conjunctivitis ( eye problems)
Treatment and advice Antibiotics It is important to counsel patients regarding partner notification, consequences of non-treatment and re-infection.
NSU – Non Specific Urethritis SYMPTOMS Urethral discharge Dysuria Penile irritation None TREATMENT Treated the same as chlamydia
Gonorrhoea Bacterial infection Passed on by unprotected sexual intercourse (vaginal, oral, anal) Mother to baby
Gonorrohoea complications PID (inflammation of the pelvis) Infertility Ectopic pregnancy Inflammation of testes Conjunctivitis ( eye problems)
Treatment and advice Antibiotics (injection or tablets) It is important to counsel patients regarding partner notification, consequences of non-treatment and re-infection.
Modes of transmission Genital warts are benign skin lesions. Most often by sexual contact May be transmitted at birth.
Treatment options Cryotherapy (freezing) Home treatments – creams Surgical intervention
HSV – Herpes Simplex Itching, tingling, inflammation and discomfort in the area affected. General flu-like symptoms Painful blisters, spots or red lumps. These burst and form sores, raw spots or ulcers which will crust over and new skin will form as they heal. Sites affected Genital areas Mouth Eyes
Treatment options TO RELEIVE SYMPTOMS ONLY: Anti-viral tablets And Pain relief
Trichomoniasis (TV) 10 - 50% are asymptomatic. The commonest symptoms include vaginal/urethral discharge, vulval itching, dysuria, or offensive odour. Occasionally the presenting complaint is of low abdominal discomfort.
Complications TV has been associated with problems in pregnancy Bleeding Pre term delivery Low birth weight In men, Trichomonas can cause inflammation of the penis and prostate. TREATMENT: Ant-biotics and partner notification