microbiology 2 infection control dn8

Microbiology 2Microbiology 2Infection ControlInfection Control

DN8DN8

Dr Viv Rolfe

Alternative formats and large print versions

of these handouts are available upon request.

Lecture SummaryLecture Summary

• Global and UK problem of infections

• Causes of infections– Commensal and pathogenic infection– 5 steps to an infection– Microbe-host interaction – the body’s response

to infection

• Topical issues– Hospital-acquired infection– Super-bugs

What is an Infection?What is an Infection?

• Infection - microbes enter the host, multiply and cause tissue damage.

• It is a communicable disease i.e. can be passed between people.

•41% of global disease is infectious.

HIV / AIDS, tuberculosis and malaria cause millions of deaths each year.

Global ProblemGlobal Problem

WHO – World Health Organisation

40% of people will visit health care professionals because of infections each year.

Food poisoning the most common.

5,000 patients die from hospital acquired infections each year.

Many national crises have been due to infection, e.g. BSE and CJD, meningitis, E. coli O157 outbreaks

UK ProblemUK Problem

6379

3293

22652251

2111

1879

1587

1444

1110 658Tuberculosis

Viral hepatitis

Measles

Meningitis

Mumps

Scarlet Fever

Rubella

Dysentery

Malaria

Whooping cough

+82,000 cases of food poisoning...

Source:Communicable disease surveillance centre

Cases of Infection in the UK each Year

What other infections have

been in the news?

What Causes What Causes Infection?Infection?

What Causes Infection?What Causes Infection?

• Micro organisms…– Bacteria– Viruses– Fungi– Protozoa

• Prions (small infectious proteins which don’t have a genome)

• Parasites

Name the Type of Name the Type of Microbe!Microbe!

BACTERIA

COCCI

ROD/

BACILLUS

SPIRAL

VIRUSES

PROTOZOA

e.g. amoeba

e.g. flagellate

3.9

PRIONS

PARASITE

Microscopic tic Worm – visibleto the eye

Tape worm

It could be a commensal in the It could be a commensal in the wrong place at the wrong timewrong place at the wrong time

• Commensal – a organism which lives in association with another and is harmless.

• Colonisation - the growth of organisms at a site.

• Flora - micro-organisms resident in a body site e.g. skin, gut.

Guess which are commensal colony sitesin the body.

Is sterile

Harbours commensal flora

BloodVagina

Eyelids

CerebroSpinalfluid

External

ear canalColon

Skin

Upper

Respiratory

tract

Internal

organs

Urethraopening

Semen(prior tourethra)

Is sterile


Blood

Vagina

Eyelids

CerebroSpinalfluid

External

ear canalColon

Skin

Upper

Respiratory

tract

Internal

organs

Urethraopening


Is sterile


Blood

Vagina

Eyelids

CerebroSpinalfluid

External

ear canal

ColonSkin

Upper

Respiratory

tract

Internal

organs

Urethraopening


Is sterile


Blood

VaginaEyelids

CerebroSpinalfluid

External

ear canal

ColonSkin

Upper

Respiratory

tract

Internal

organs

Urethraopening


Infections can be caused by Infections can be caused by pathogens (not commensal to pathogens (not commensal to the body)the body)

Pathogen Name Disease

Fungus Tinea Pedis Athelete’s footJock itch (groin)

Virus Hepatitis B Hepatitis B

Human Immuno-deficiency Virus (HIV)

HIV leading to aids

Bacteria Mycobacterium tuberculosis Tuberculosis TB

Clostridium difficile (C diff) Diarrhoea

Protozoa Entamoeba histolytica Amoebic Dysentry

Parasites Tapeworm Malnutrition

InfectionsInfections

5 Steps to Infection5 Steps to Infection

•The presence of an inFectious Agent

•A Reservoir where agent is multiplying and waiting to infect!

•A route of Transmission.

•A route of Entry into host.

•Inadequate natural defenses in a Susceptible individual

Name some possible

reservoires in a hospital ward.

Reservoires

Name some possible routes of transmission in a

hospital ward.

e.g. air, water, touch or a vector (mosquito)

How does the Body How does the Body Respond to Infection?Respond to Infection?

Number ofpathogens

Incubation

Nosymptoms

Prodromal

Mildsymptoms

Acute illness

Identifiablesymptoms

Fatal if growthof microbescontinues

Recovery

Microbes respondingto therapy and immunity

Depends on SusceptibilityDepends on Susceptibility

• Healthy individuals combat infection so only suffer acute (short term) illness.

• In susceptible groups infection can be worse….– Older/younger– Pregnancy– Poor nutrition– Illness– Medication, drugs and surgery– Stress– Genetic predisposition

Body response to infectionBody response to infection

• Local inflammation (reaction by innate and acquired immune defenses).

• Systemic response including release of pyrogens in the blood which cause fever.

Localised swelling/odemaLocalised swelling/odema

Virus

particles

Attackinglymphocytes in

the immune system

The immune system provides a defence against infection.Sometimes, a pathogen combats our defences.

HIV Virus

Topical IssuesTopical Issues

HAIHospital or Healthcare Acquired Infections

StatisticsStatistics

• 1 in 10 people will acquire a hospital infection.

• They cost the health sector 1 billion pounds per year.

• People spend 2.5 times longer in hospital.

• Also known as NOSOCOMIAL infections.

Causes of HAICauses of HAI

• Susceptible hosts – stressed, ill health, medication.

• Close proximity to other people.

• Drugs don’t work.

• Inadequate infection control (e.g. washing hands).

MOST COMMON INFECTIONS

Blood infection via needles, drips

Infection after surgery

Skin

Chest

Urinary tract

MOST COMMON BUGS

E coli

Staphylococcus

Candida

Clostridium difficile

E coliC dif

Staphy Candida

The Matron’s Charter (2004)

• 10 principals for delivering cleaner hospitals

• Matrons to organise cleaning

• Patient feedback• Infection control training

Drug Resistant Micro-organismsDrug Resistant Micro-organisms

Drug Resistant Micro-organismsDrug Resistant Micro-organisms

• These SUPER-BUGS make HAI an evengreater problem.

• Increasing numbers of bacteria are resistant to antibiotics so many HAI cannot be treated.

• MRSA kills 5000 people each year.

Methicillin-resistant Staphylococcus aureus MRSA

Oxicillan-resistant S. aureus ORSA

Vancomycin-resistant Enterococci VRE

Superbugs….Superbugs….

•Staphy is a commensal living on the skin

•It can infect the lungs causing pneumonia

•Transmitted by physical contact and in the air

•Current preventive measures - hand washing and patient isolation

MRSA / ORSAMRSA / ORSA Staphy

•Commensal Enterococci in the gut

•Infects vulnerable and long stay patients

•Causes urinary tract infection e.g. associated with use of catheters.

VREVRE

Lecture SummaryLecture Summary

• Global and UK problem of infections

• Causes of infections– Commensal and pathogenic infection– 5 steps to an infection– Microbe-host interaction – the body’s response

to infection

• Topical issues– Hospital-acquired infection– Super-bugs

microbiology 2 infection control dn8

Documents

infection microbes

commensal colony sites

susceptible groups infection

uk problem of infections

hospital ward

body site

infectious agent

global disease