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Transcript of Microorganism
invasion and multiplication of microorganisms in body tissues, which may be clinically unapparent or result in local cellular injury due to competitive metabolism, toxins, intracellular replication or antigen antibody response.
Study of microorganism
Small, unicellular microorganisms that are capable of rapid reproduction.
substance forming the cell walls of many bacteria, consisting of glycosaminoglycan chains interlinked with short peptides.
space bordered by two selective permeable barriers, i.e., biological membranes, which are the inner membrane (i.e., cytoplasmic membrane) and the outer membrane in Gram-negative bacteria.
a microscopic membrane of lipids and proteins that forms the external boundary of the cytoplasm of a cell or encloses a vacuole, and that regulates the passage of molecules in and out of the cytoplasm.
also known as lipoglycans, and endotoxin are large molecules consisting of a lipid and a polysaccharide composed of O-antigen.
ability to hemolyze (burst) red blood cells in blood agar.
Staphylococcus aureus (S.Aureus)
The major pathogen of this genus and may be found as normal flora ( nose, skin).
Causes infection especially when resistance is lowered by a break in the skin or in the mucous membranes.
A common cause of
infections and may also cause
in individuals with reduced resistance.
Methicillin-Resistant Staphylococcus Aureus (MRSA)
that makes the organism resistant to penicillins and cephalosporins normally used for treatment and renders these antibiotics ineffective.
Tests are available to indicate the presence or absence of this enzyme and help determine the most favorable treatment.
Round, gram-positive bacteria arranged in chains.
Some are nonpathogenic, others are dangerous to humans.
Part of the normal flora of the upper respiratory tract and skin.
Some bacilli are gram positive and others are gram negative.
Enterobacteriaceae are a large family of gram-negative bacilli found mainly in the intestinal tract.
Many of them will cause infections in other body locations.
One type, Escherichia coli, is most frequently associated with UTIs.
The group of Salmonella organisms is a major cause of foodborne illnesses worldwide.
Clostridium botulinum, which causes botulism.
Clostridium tetani, which causes tetanus
Main pathogen is Vibrio cholerae whose enterotoxin causes cholera.
Spiral-shaped or corkscrew-shaped organisms.
Rods that are twisted in various shapes.
Classified as a separate phylum of bacteria.
Treponema pallidum, cause the sexually transmitted infection syphilis.
Lyme disease is a deer tick-borne disease.
Mycobacterium tuberculosis is the causative agent of tuberculosis.
Mycobacterium leprae, is the cause of leprosy.
An obligate parasite, but it does not live in arthropod hosts.
Must invade living cells to reproduce.
Disease: Chlamydia trachomatis is an STI.
Very tiny bacteria lacking a rigid cell wall.
Cause Mycoplasma pneumoniae, and a type of venereal disease.
an infective agent that typically consists of a nucleic acid molecule in a protein coat, is too small to be seen by light microscopy, and is able to multiply only within the living cells of a host.
Dermotropic – infected skin cell
Neurotrophic – infected nerve cell
Viscerotropic – infect organ of digestive tract
Pneumotropic – infected respiratory system
The following criteria are used to classify viruses:
Morphology – structure of capsid – presence or absence of envelope.
Size of the virion
Type of host/host structures the virus infected
- Bacteriophages: infect bacterial cells
- Plant viruses infect plant cells
- Animal viruses are subgrouped by the tissues they attack:
1. Dermotrophic: if they infect the skin
2. Neurotrophic: if they infect nerve tissue
Genome composition – DNA / RNA– ds/ss DNA and ds/ss RNA
Viruses are divided into three groups, based on the morphology of the nucleocapsid and the arrangement of capsomeres.
Symmetry of viruses
Arrangement of capsomers in the virus.
Two primary shapes of virus is rod and spherical.
Rod shaped virus-helical symmetry
Complex symmetry ( Poxviruses ).
Helical symmetry ( influenza & rabies viruses ).
(the complete, infective form of a virus outside a host cell, with a core of RNA or DNA and a capsid.)
the nucleic acid core and surrounding capsid of a virus; the basic viral structure.
is a basic subunit of the capsid, an outer covering of protein that protects the genetic material of a virus
Baltimore Classification of viruses
The division of the viruses into classes based on genome type and mode of replication and transcription
Suggested by David Baltimore – Seven Baltimore classes.
Major groups of viruses are distinguished first by their nucleic acid content as either DNA or RNA
RNA and DNA viruses can be single-stranded (ssRNA, ssDNA) or double-stranded (dsRNA, ssDNA)
Recovery period -
symptoms begin to subside
Acute period -
symptoms are most severe
Prodromal period -
mild symptoms appear; disease is very contagious
Incubation period -
disease develops, but symptoms are not present
pathogen enters body
The classification of organisms in an ordered system that indicates natural relationships.
All bacteria stem from a common ancestor and diversified since, consequently possess different levels of evolutionary relatedness
Different bacteria may have different metabolic abilities
Different bacteria thrive in different environments, such as high/low temperature and salt
There are many structural differences between bacteria, such as cell shape, Gram stain (number of lipid bilayers) or bilayer composition
Some bacteria are pathogenic to plants or animals
The highest taxonomic rank of organisms
A group of Classes with similar distinctive characteristics.
An individual belonging to a group of organisms (or the entire group itself) having common characteristics
Consonants - Vowels
A - F
microorganisms that are similar to bacteria in size and simplicity of structure but radically different in molecular organization. They are now believed to constitute an ancient intermediate group between the bacteria and eukaryotes.
Naming A Bacteria
International Committee Binomial Nomenclature
Genus + Species =
Mandatory to Classify Before Naming
A microbiota is a micro-organism or bacteria that will reside in a human body that are generally symbiotic in nature. These will be beneficial to the body and will act along with the immune system to rid harmful bacteria from the body in most normal cases.
interaction between two different organisms living in close physical association, typically to the advantage of both.
between two organisms of different species in which one of them benefits from the association whereas the other is largely unaffected or not significantly harmed or benefiting from the relationship.
between individuals of different species in which both individuals benefit from the association.
Factors Normal Biota
Lysozyme and bile
Protein molecule that attach microbes to human cells. Friendly bacteria evolve.
is "the ecological community of
, symbiotic, and pathogenic microorganisms that literally share our body space."