Prepare by S.V ****************************************************************************************** 09/21/07
Microbiology
********
-Introduction: Microbiology is a branch of Biology deals with study of micro organisms.
-Micro organisms: are present everywhere in the earth includes air, soil, water, plants, animal, humans and dead materials
-Micro organisms: are unicellular and Milticellular
-Some of them are pathogenic (causing disease) and most of them are non-pathogenic.
-Micro organisms: are very small to be seen only through microscope
-Antory Van Leeuwenhork ( 1675 netherlands) who observed bacteria and protozoa( micro organisms) first with this sample microscope. so he is a father of microbiology.
-The microorganisms or microbes are classified based on the presence of nucleus. These are Prokaryotic micro organisms, Eukaryotic micro organisms and virus.
Prokaryotic / Eukaryotic-The nucleus and membrane bound organelles are not
present
-The side of the cell is 0.2-2µm
-The genetic material is freely distributed in the
cytoplasm.
-The ribosome 70s. S=Svedberg unit: to measure the
size of ribosome. Eg: Bacteria / -Nucleus and membrane bound organelles
(mitochonchondri) endoplasmic reticulum and
Golgi body are present.
-The cell size is 2-20µm
-The genetic material is present in the nucleus
-The 80s ribosome is present
Eg: fungi and protozoa
- the virus is also considered as microorganism but it is call acellur and non cellular organism.
Bacteria
-It is a prokaryotic microorganism the size range between 0.2-0.5 µm
-Most of them are nonpathogenic because it doesn’t contain virulent factor properties (toxic components) and some of them are pathogenic (contains virulent factors).
-Most of the bacteria can live in extreme condition and can change the environment.
Morphology of Bacteria
- There shapes are many shapes of bacteria including Cocci, Bacilli and Spirochetes
I. Cocci or Coccus: some of the bacteria are look like spherical shape or round shape, such type of bacteria are called Cocci they are different type of Cocci based on the number of cell and arrangement.
a) Mono Coccus: single cell
b) Diplococcus noncapsulated: two cell joined together to form this structure (pair) and it don’t have membrane which surrounded the cell.
c) Diplococcus encapsulated: two cells joined together with membrane coated over the cell.
d) Streptococcus some bacteria look like chain like structure is called Streptococcus
e) Staphylococcus the bacteria look like clusters of grape.
II. Bacilli or Bacillus : most of the bacteria are look like rod shape or cylinder shape. This is called bacilli, there are several type
- Mono Bacillus: single rod shaped
- Diplo Bacillus: two rods joined together to form this shape
-Flagellated Bacillus: some bacteria have flagella (hair like structure) present in the cell wall which help the bacteria move from one place to another place.
-Coccobacillus: it look like round as well as rod such type of bacteria are called coccusbacillus.
-Comma shaped bacillus: some bacteria look like comma shape
-Sporbearing bacillus: some bacteria can release the spore which is highly resistant to live in extreme condition and can live for more than too fears such type is called spore bearing bacillus.
-Streptobacillus: chain like arrangement
III. Spirochetes: the bacteria look like spiral shape structure
Classification of Bacteria
The classification of bacteria is base on the cell wall. There are:
- Thick walled bacteria
- Thin cell walled
- Wall less bacteria
I. Thick wall bacteria
Some bacteria are having thick and rigid cell wall is made up of peptidoglycan layer (polysaccharide+peptid) it provides protection to the bacteria. There are two types of thick cell walled bacteria.
Gram positive bacteria and Gram negative bacteria
The gram positive bacteria and gram negative bacteria can be observed or identified by Gram staining technique.( Hans Christian Gram 1884) in the technique the Gram positive appears like violet color or blue color after added the reagent. The gram negative bacteria appear like pink color or red color after adding the reagent.
Gram positive bacteria
-It contains more than 40 layers of peptidoglycan in the cell wall give more rigid (strong) and provides protection of the bacteria.
-The cell wall also contain Fibrillar layer which acts as a toxic component (virulent factor).
-The cell wall contain Teichoicacid and Lipoteichoic acid which give support to the cell wall.
Gram negative bacteria
-The cell wall of the gram negative bacteria contain single layer of peptidglycan
-The cell wall also contain Lipopolysaccharide which acts as a virulent factor.
Gram positive bacteria are two shape normally:
1. Gram positive cocci
Ex. Staphylococcus species, streptococcus species, entorococcus faecalis
2. Gram positive rods
Ex. Bacillus species, clostridium species, corynebacterium diphtheriae
Gram negative bacteria are two shape normally:
a.Gram negative cocci: Ex. Neisseria species,
b. Gram negative rods:
Ex. Salmonella species, shigella species, Escherichia coli, Vibrio cholerae, Campylobacteria jejuni,
Pseudomonas species, Helicobactor pylori, Klebsiella pneumoniae, Proteus species, Bacteroides pertusis,
Brucella species, Yersinia species, Fronciesella tulerensis, Legionella pneumophila, Haemophilus
influenzae.
Acid Fast Bacteria
Acid fast is the name of the staining technique to identify some bacteria.
-The acid fast bacterial cell wall contain single layer of peptidoglycan, Fatty acid and waxes.
-The Fatty acid and waxes acts as virulent factor of bacteria wich cause diseases of the humans.
Ex. Myobacterium tuberculosis, Myocobacterium leprae, Nocardia species.
II. Thin cell wall bacteria:
Some of bacterial is very thin and it is flexible in nature
Ex. Spirochetes
III. wall less bacteria
The wall less bacteria which do not have the cell wall.
Structure Properties of Bacteria
Cell wall: the outer layer of the bacteria which is made up of peptidoglycan. It protects the bacgteria.
Cytoplasmic membrane: it is a layer which surround the cytoplasm. It acts as a permeable layer and it allowed the inside toxic
components to go outside and cause diseases to the humans body.
Ribosome: the synthesis of protein take place in ribosome.
Chromosome: it contain DNA (Deoxy Ribose Nucleic Acid) as a genetic natural.
Plasma: it is an extrachronosomal circular DNA which contains ß-lactamase enzyme provide to some antibiotic like penicillin.
Inclusion: it is an energy stored material which give energy to live the bacterial cell.
Virulent properties of bacteria
The pathogenesis of bacteria refers to the presence of virulent factor (toxic component) in the bacteria. The virulent factor is the main causative thing for diseases. There is several type of virulent factor.
i) Adherence factor: the bacteria contain hair like structure called Flagella and Pilus which help he bacteria to adhere the host cell surface. After adherence the bacteria can release the toxic material and make disease.
ii) Capsule: it is presents in the cell wall of bacteria which is made up of popolysaccharide which fight against phagocytic cell (type of immune cell) like Microphage. Because whenever the bacteria is enter into the body the phagocytic cell immediately attack the bacteria and kill is so, if the capsule is present the bacteria can easily live in the human body.
iii) Exotoxins: it is found in gram positive and gram negative bacteria it is made up of polypebtides and has got two subunit normally. A-subunit and B-subunit. The function of B-subunit is to bind the host cell after that the subunit release the toxin then the toxin can easily attack the various organs like Kidneys, heart, liver, lungs act. It also cause hemorrhage (bleeding) and swelling.
iv) Endotoxin: it is found in the gram negative bacteria which is made up of Lypopolysaccharids. It cause fever, general ache and general weakness.
v) Enzyme: the bacteria contain some enzymes which act as a toxic enzymes. The function of this enzymes is to attacks the cell membrane, tissue matrix and connective tissues lead to paralysis.
vi)Enterotoxin: this toxin is present inside the cell of bacteria which attacks the mucus membrane in the intestinal tract and cause vomiting and diarrhea.
vii) Cell surface carbohydrates and proteins: the bacteria also contain some toxic carbohydrate and proteins which attacks the immune cell in the human body so that the bacteria can easily attacks the cells.
Culture of Bacteria
The culture (grow) of bacteria is very important to find the name of the bacteria and with this culture we can choose the antibiotic to cure the diseases.
Requirement for Bacteria Culture
1. petridish: it is a glass plate in this we can cure the culture bacteria.
2. Medium: it is nutrient material which feed the bacteria to grow
3. Incubation chambar: highly sterilized chambar to keep the culture plate here.
4.Water: to clean the glass wares
5. Patient sample: blood, sputum, stool, urine, mucus, wound tissue…
Procedure: Medium pour Blood sample put different
(antibiotic) Zone formation
Incubation for 2 days
→ → → bacteria
Petridish ceftriaxone
Or petriplate penicillin
Clavithromycin
Erythromycin
Keep it into Microscope and find out
Gram positive cocci bacteria infection
I. Staphy loccal infection
The staphylococcus bacteria are clusters of gram like shape. There are three important staphyloccus species are causing disease.
i) Staphylococcus aureus: it is a gram positive cocci bacteria
Phathogenesis
- Coagulose enzyme: this enzyme is present in the bacteria which stimulates the prothrombin to clot the blood in the injured region and make infections because the prothrombin is acting as a blood clotting factor involve in the blood clotting. One the blood is clotted in the injured region the bacteria can make colonies and cause wound infection.
- Catalase: it is an enzyme which breaks the H2O2 (hydrogen peroxide) in to H2O+O2 because the H2O2 act as a antibacterial agent in the body so that the enzyme can attack this H2O2 and cause infection.
- Protein-A: it is a protein toxic which fight against the immure protein like complement protein.
- Enterotoxin: it cause a diarrhea and vomiting while eating the contaminated or spoiled food and water.
- Toxic shock syndrome toxin: it is a toxin released from the bacteria. The function of this toxin is to make toxic shock in the wound regionally especially the vaginal wound.
- Exfoliatin: this is an toxin which attacks the epidermal layer of the skin to make scales in the skin.
- Leukocidin: it is an another toxin which attacks the leukocyte(WBC)
Disease
- Abscess or wound infection: infection in the wound region with pus.
- Gastritis: inflammation in the digestive tract. The symptom like diarrhea, vomiting, abdominal pain, loss of appetite etc.
- Toxic shock syndrome toxin: sever shock pain in the vaginal wound region with the present of pus.
- Folliculitis: inflammation with pus in the follicles.
- Staphyloccal scalded skin syndrome:The inflammatory condition in epidermal layer of the skin. The damage or breakdown of the epidermis which make skin scales.
This disease is very common in young children(below 5 year).
Transmission
- Transmitted from contaminated or spoild food and water
- It also transmitted from infected patient to normal person and environment
Diagnosis
Blood culture and blood smear to find out these bacteria.
Coagulase test: takecitrated plasma (plasma contain sodium citrate) and add the bacterial culture. Keep the tube for incubationat 31 0c for 4 hour. If any clot formation take place confirm that the patient is infected with staphylococcus aureas.
Treatment: vacomycin is an antibiotic to kill this bacteria.
Prevention:- avoid contact with infected patient
- Make yourself proper hygieon
- Avoid contaminated food and water
ii) Staphylococcus epidermidis: It is a gram positive bacteria
Virulent factor: Glycocalyx: it is made up of glycoprotein and polysaccharide which is found in the cell wall of S.epidermidis. the function of glycocalyx is to adhere in the prosthetic (arrificial) heart valves and prosthetic hip and make infections.
Diseases
1. Endocaditis:it is an inflammation condition of prosthetic heart valve in the endocosodium of the heart. The S.epidermidis bacteria can release the glycocalyx and stick in to prosthetic heart valve and make infection as well as damage in the valve.This condition the patient have symptom like hemorrhage, circulatory problem, serve, chest pain, nausea and heart attack.
2.Prothetic hip infection: the inflammation in the prosthetic hip region especially artificial hip implanted patient. The patient have symptom like sever joint pain, swelling in the joint etc.
3. Neonated sepsis: it is an inflammatory and infection in the blood of neonate (just born baby or below 1 month baby) the S.epidermidis is normally found in the vaginal region, during child birth the bacteria enter through placenta and spread through out the blood and entire organs of the baby to cause this infection. The symptom like hemorrhage, diarrhea, skin rashes, jaundice etc.
Transmission: During dental surgery, childbirth the bacteria can easily enter and cause disease.
Diagnosis: Blood culture and blood smear to identifythese bacteria.
Treatment: Vacomycin + Hentamicin + Rifampin
Prevention: During dental surgery, the patient should be treated with Cefazolin (antibiotic). During pregnancy the women should maintain hygiene.
iii) Staphylococcus saprophyticus: it is gram-positive bacteria
Virulent factor: pilus: it is a heir like structure which is present outside the cell wall. The function is to adhere the host cell surface especially the urinary tract.
Disease:
urinary tract infection (UTI), the urinary tract infection consist of urethra, bladder, prostate(non), ureter and kidney. The bacteria can easily attack the urinary tract and make infection.
-Urethritis: the inflammation occurs in the urethra
-Cystitis: the inflammation condition in bladder
-Prostatitis: the inflammation in the prostate region of the man
- Pyclorephritis:inflammatory in the kidney. The UTI symptom like pyuria, Nocturia, dysuria, hematuria and foul smell urine
Transmission: through ascending way to get inside the urinary tract. The unsterilized urinary catheter cause UTI
Diagnosis:urine culture to find out these bacteria
Treatment: Norfloxacin (antibiotic) alone or Norfloxacin + Trinethoprin sulfanethoxazole as a combination therapy for sever UTI.
Prevention: the urinary catheter should be sterilized properly before insertion. The toilet should be cleaned always especially in hospital.
II. Steptococcal infection
The streptococcus bacteria are classified in to three group namely
Group A Streptococcus pneumonia: it has α-Hemolytic enzyme that lye hemoglobin and make color change( from red to 50/gree color) during culture process.
Group B Streptococcus pyogenes, streptococcus agalatias, streptococcus mutans and streptococcus sanguis: this bacteria have ß-hemolytic enzyme that make 100% green color during the culture process.
Group C Enteroccus faecels: there will not be any colors change during culture.
i. Streptococcus pneumonia: it is a gram positive bacteria look like chain structure.
Virulent factor:
- pilus: help the bacteria to attach into the host cell
- capsule: it is made up by of polysaccharides which fight against phagocytic cell like macrophage
- Pneumolysin: it is an enzyme that invade (attach) the cell membrane in the respiratory tract it also have hemolytic action and against immune cell.
Disease
-Pneumonia: the inflammation condition in the alveoli region (air sac) of the lung. The symptom like difficult to breath, cold, cough, yellow color sputum, fever and malaise.
-Sinusitis: the inflammatory condition in the sinus region. The symptom like sneezing, runny, nose, swollen in the sinus, pain and fever.
-Otitis media: the S. pneumonia also attack the middle ear (eardrum) and make infection there. The symptom like ear pain, difficult to hear the sound and fever.
Transmission: Through respiratory droplet from infection patients.
Diagnosis: Sputum culture, the culture plate will become 50% green color from red color
Treatment: Cephalexin (antibiotic) to kill S. pneumonia + Cetrizene for runny nose
Prevention: avoid contact with infection patient
ii. Streptococcus pyogenes: it is a gram positive look like chain structure.
Virulent factor
- capsule: have “antiphagocytic”
- streptolysin “s”and “o”: it has hemolytic action. And lyses the hemoglobin molecule an important for finding the bacteria during blood culture.
- Protein F:This protein specifically attach into the fibronectin (a protein is found in the pharynx region) and cause inflammation in the pharynx region.
- Dnases: it is an enzyme that attach DNA
- Exotoxin: it is also called erythrogenic toxin which make skin rashes (scars) after the scarlet fever
- Hyaluronidase: the enzyme which attach the hyaluronic acid which is found in the connective tissue like skin and make inflammation
Diseases
- pharyngitis: the inflammatory condition in the pharynx region. The symptom like red color swollen in the pharynx region, sore throat, difficult to swallow food, pain in the pharynx region, fever etc.
- Cellulitis: theinflammation in the connective tissue like skin especially the lower arms and lower legs will have infection. The symptom like red colour rashes, pain, fever etc.
- Rheumatic fever: the inflammatory condition in the heart, skin and joint. The patient will have symptom like murmur, obstruction in the heart resell, swelling in the joint, pain and fever and skin rashes.
- Impetigo: the common skin disease in children. The symptom blister in the skin, red rashes, fever, malaise etc
Transmission :Transmitted easily from infection person to normal person while touching the body and respiratory droplets.
Diagnosis:blood culture and blood smear with gram staining technique. Physical examination and patient history