Bacteria• Bacteria are pro karyotes

“first seed” (single cells that do not contain a nucleus, or membrane bound organelles).

• Bacteria are microscopic and can only be seen through a microscope

• There are 2 Domains of bacteria, Eubacteria and Archaea

Eubacteria “true bacteria”• Typical “monerans” found

where humans live• Evolution of the 3 Domains

                     

   

Archaea “archaic/old”extremophiles

• Methanogens• Thermophiles• Acidophiles• Halophiles• Alkaliphiles• Psychrophiles• Xerophiles• Barophiles

• Archae vs Bacteria

Bacteria Characteristics• Bacteria are

distinguished from other living things because of their cell structure:

• All bacterial cells have a cell wall surrounding a cell membrane, inside of which lies the unbound nuclear matter and other material.

• Bacteria have extra genomic DNA that is round and called a “plasmid”

• Plasmid Cloning

Bacteria Classification• There are three types of bacterial cells, based on

shape: spherical (coccus), rodlike (bacillus), and spiral (spirillum).

Coccus

Bacillus

Spirilla

• Some bacteria have flagella for locomotion and some have pili to transfer DNA (conjugation) and to stick to substrates of host cells

Bacterial Chemotaxis

Gram Staining• The Gram stain is named

after the 19th century Danish bacteriologist who developed it.

• The bacterial cells are first stained with crystal violet. then treated with alcohol or acetone, whichwashes the stain out of gram-negative cells and then counterstained.

• Bacteria that are not decolorized by the alcohol/acetone wash are gram-positive.

• Gram Stain Animation

Gram +

• Stains purple• Cell wall 90%

peptidoglycan

Gram -

• Stains red• Multi-layered cell wall

with inner and outer membranes and an intermembrane space

Harmful Bacteria• A number of bacteria

cause disease, these are called pathogenic bacteria.

• They can cause diseases of plants, animals, fungi, protists and other bacteria

• E. coli infection

• Salmonella infection

• Some bacterial diseases include: strep throat, scarlet fever, toxic shock syndrome, pneumonia, ear infections, gonorrhea, syphilis, Tuberculosis

• Bacteria can also be used by some countries to harm other countries in an act called bioterrorism

Eczema w/ 2o infection

Helpful Bacteria• actinomycetes,

produce antibiotics such as streptomycin and nocardicin

• live symbiotically in the guts of animals

• Bacteria put the tang in yogurt and the sour in sourdough bread

• roots of certain plants, converting nitrogen into a usable form.

• break down dead organic matter

• of such immense importance because of their extreme flexibility, capacity for rapid growth and reproduction, and great age - the oldest fossils known, nearly 3.5 billion years old

• used in genetic engineering

Bioremediation

Wound infectionDefinition

of

wound

infection•1992

US

Centre

for

Disease

Control

•Defined

the

following:

•Surgical

site

infections

•Superficial

incisional

infection

•Deep

incisional

infections

•Organ

space

infections

•Surgical

site

infections

must

fulfill

the

following

criteria

•Infection

must

occur

within

30

days

of

surgery

•Infection

must

involve

only

the

skin

and

subcutaneous

tissue

•There

must

be

at

least

one

of

the

following

•Purulent

discharge

from

a

superficial

infection

•Organisms

isolated

from

aseptically

obtained

wound

culture

•Must

be

at

least

one

of

the

following

signs

of

infection

•Pain

or

tenderness

•Localised

swelling

•Redness

or

heat

Predisposing

factors•General

factors

•Age,

obesity,

malnutrition

•Endocrine

and

metabolic

disorders

•Hypoxia,

anaemia

•Malignant

disease

•Immunosupression

•Local

factors

•Necrotic

tissue

•Foreign

bodies

•Tissue

ischaemia

•Haematoma

formation

•Poor

surgical

technique

•Microbiological

contamination

•Type

and

virulence

of

organism

•Size

of

bacte

riological

dose

•Antibiotic

resistance

Aerobic

pathogens

in

wound

infections•Staphylococcus

aureus

(17%)

•Enterococci

(13%)

•Coagulase-negative

staphylococci

(12%)

•Escherichia

coli

(10%)

•Pseudomonas

aeruginosa

(8%)

•Enterobacter

species

(8%)

•Proteus

mirabilis

(4%)

•Klebsiella

pneumoniae

(3%)

•Candida

species

(2%)

Prevention

of

wound

infection•Exogenous

•Sterilisation

of

instruments,

sutures

etc

•Positive

pressure

ventilation

of

operating

theatres

•Laminar

air

flow

in

high

risk

areas

•Exclusion

of

staff

with

infections

•Endogenous

•Skin

preparation

•Mechanical

bowel

preparation

•Antibiotic

prophylaxis

•Good

surgical

technique

Wound

infection

rates•Risk

of

wound

infection

varies

with

type

of

surgery

•Infection

rate

can

be

reduced

with

antibiotic

prophylaxis

Clean

surgery•No

viscus

opened

(e.g.

hernia

repair)

•Infection

rate

typically

1-2%

Clean-contaminated•Viscus

opened

but

no

spillage

of

gut

contents

(e.g.

right

hemicolectomy)

•Infection

rate

usually

<10%

Contaminated•Viscus

opened

with

inflammation

or

spillage

of

contents

(e.g.

colectomy

for

obstruction)

•Infection

rate

15-20%

Dirty•Intraperitoneal

abscess

formation

or

visceral

perforation

•Infection

rate

40%

Antibiotic

prophylaxis

•Prophylaxis

is

the

use

of

antibiotics

to

prevent

infection

•Treatment

is

their

use

to

eradicate

established

sepsis.

•Prophylaxis

important

in:

•Surgery

with

a

high

incidence

of

post-operative

infection

(e.g.

colonic

surgery)

•Surgery

where

infection

would

be

hazardous

(e.g.

prosthetic

valves)

•Need

to

consider:

•The

use

of

an

appropriate

antibiotic

based

on

likely

bacteria

and

tissue

penetration

•Cefuroxime

&

metronidazole

for

colonic

surgery

•Benzylpenicillin

for

peripheral

vascular

surgery

•Timing

and

duration

of

administration

•Intravenous

administration

at

induction

•Number

of

doses

-

usually

no

more

than

three

doses

BibliographyHoran

T

C,

Gaynes

R

P,

Martone

W

J,

Jarvis

W

R,

Emon

T

G.

CDC

definitions

of

nosocomial

surgical

site

infections,

1992:

a

modification

of

CDC

definitions

of

surgical

wound

infections.

Am

J

Infect

Control

1992;

20:

271-274.McDonald

M,

Grabsch

E,

Marshall

C,

Forbes

A.

Single-versus

multiple-dose

antimicrobial

prophylaxis

for

major

surgery:

a

systematic

review.

Aust

N

Z

J

Surg

1998;

68:

388-396.

Wound infectionDefinition

of

wound

infection•1992

US

Centre

for

Disease

Control

•Defined

the

following:

•Surgical

site

infections

•Superficial

incisional

infection

•Deep

incisional

infections

•Organ

space

infections

•Surgical

site

infections

must

fulfill

the

following

criteria

•Infection

must

occur

within

30

days

of

surgery

•Infection

must

involve

only

the

skin

and

subcutaneous

tissue

•There

must

be

at

least

one

of

the

following

•Purulent

discharge

from

a

superficial

infection

•Organisms

isolated

from

aseptically

obtained

wound

culture

•Must

be

at

least

one

of

the

following

signs

of

infection

•Pain

or

tenderness

•Localised

swelling

•Redness

or

heat

Predisposing

factors•General

factors

•Age,

obesity,

malnutrition

•Endocrine

and

metabolic

disorders

•Hypoxia,

anaemia

•Malignant

disease

•Immunosupression

•Local

factors

•Necrotic

tissue

•Foreign

bodies

•Tissue

ischaemia

•Haematoma

formation

•Poor

surgical

technique

•Microbiological

contamination

•Type

and

virulence

of

organism

•Size

of

bacte

riological

dose

•Antibiotic

resistance

Aerobic

pathogens

in

wound

infections•Staphylococcus

aureus

(17%)

•Enterococci

(13%)

•Coagulase-negative

staphylococci

(12%)

•Escherichia

coli

(10%)

•Pseudomonas

aeruginosa

(8%)

•Enterobacter

species

(8%)

•Proteus

mirabilis

(4%)

•Klebsiella

pneumoniae

(3%)

•Candida

species

(2%)

Prevention

of

wound

infection•Exogenous

•Sterilisation

of

instruments,

sutures

etc

•Positive

pressure

ventilation

of

operating

theatres

•Laminar

air

flow

in

high

risk

areas

•Exclusion

of

staff

with

infections

•Endogenous

•Skin

preparation

•Mechanical

bowel

preparation

•Antibiotic

prophylaxis

•Good

surgical

technique

Wound

infection

rates•Risk

of

wound

infection

varies

with

type

of

surgery

•Infection

rate

can

be

reduced

with

antibiotic

prophylaxis

Clean

surgery•No

viscus

opened

(e.g.

hernia

repair)

•Infection

rate

typically

1-2%

Clean-contaminated•Viscus

opened

but

no

spillage

of

gut

contents

(e.g.

right

hemicolectomy)

•Infection

rate

usually

<10%

Contaminated•Viscus

opened

with

inflammation

or

spillage

of

contents

(e.g.

colectomy

for

obstruction)

•Infection

rate

15-20%

Dirty•Intraperitoneal

abscess

formation

or

visceral

perforation

•Infection

rate

40%

Antibiotic

prophylaxis

•Prophylaxis

is

the

use

of

antibiotics

to

prevent

infection

•Treatment

is

their

use

to

eradicate

established

sepsis.

•Prophylaxis

important

in:

•Surgery

with

a

high

incidence

of

post-operative

infection

(e.g.

colonic

surgery)

•Surgery

where

infection

would

be

hazardous

(e.g.

prosthetic

valves)

•Need

to

consider:

•The

use

of

an

appropriate

antibiotic

based

on

likely

bacteria

and

tissue

penetration

•Cefuroxime

&

metronidazole

for

colonic

surgery

•Benzylpenicillin

for

peripheral

vascular

surgery

•Timing

and

duration

of

administration

•Intravenous

administration

at

induction

•Number

of

doses

-

usually

no

more

than

three

doses

BibliographyHoran

T

C,

Gaynes

R

P,

Martone

W

J,

Jarvis

W

R,

Emon

T

G.

CDC

definitions

of

nosocomial

surgical

site

infections,

1992:

a

modification

of

CDC

definitions

of

surgical

wound

infections.

Am

J

Infect

Control

1992;

20:

271-274.McDonald

M,

Grabsch

E,

Marshall

C,

Forbes

A.

Single-versus

multiple-dose

antimicrobial

prophylaxis

for

major

surgery:

a

systematic

review.

Aust

N

Z

J

Surg

1998;

68:

388-396.

Bacteria are useful in making antibiotics and in biotechnology.

Fig. 37.8: The role of soil bacteria in the Fig. 37.8: The role of soil bacteria in the nitrogen nutrition of plants.nitrogen nutrition of plants.

Symbiotic bacteria assist in digestion

Producers in Geothermal Vents

Reproduction

• Bacteria reproduce asexually by binary fission• Bacterial Conjugation (lateral/horizontal gene exchange)

• Bacterial Transformation (lateral/horizontal gene exchange)

• Bacteria life cycle

Response to the Environment

• Intracellular signaling not only brings bacteria together in biofilms (through Quorum sensingA process by which a bacterium detects the density of other bacteria in an area), it also regulates the coordinated delivery of high doses of these antibiotics from the denser bacterial population.

• Biofilm Life Cycle

Bacterial Links• Bioterrorism:

• Bacterial Cell Walls:

• 10 Ways a World Will End: Monster Plague

• Discovery of the Germ Theory

• Antibiotics Tutorial

• Anti-antibiotics/Efflux Pump

• Immunology Primer

• When Worlds Collide, Macro vs. Micro

• Immuno- biology Animations