Introduction to Microbiology Flashcards
Louis pasteur
Louis Pasteur demonstrated that microorganisms to not arise spontaneously in media but when introduced from the environment he also established that microorganisms can be inactivated by heat and pressure and therefore that food could be preserved by process that we know as pasteurization. He also develop vaccines against chicken cholera, anthrax and rabies
Joseph lister
After reading the work of Louis Pasteur Joseph Lister a surgeon started to employ a number of aseptic techniques in his surgery is sterilized the surgical instruments with heat and use fennel in surgical dressings these techniques resulted in fewer postoperative infections providing strong indirect evidence that microorganisms play a role in disease
Robert Koch
Robert Koch was the first person to demonstrate directly that bacteria cause disease cause she initially worked on anthrax and demonstrated at Derek relationship between exposure to bacillus anthracis and the disease anthrax he developed what we known as Koch postulates which a list of criteria to verify a particular age and is responsible for a specific disease he then worked on mycobacterium tuberculosis and prove that it is the causative agent of tuberculosis
Kosh postulates
The criteria developed by Robert cost to demonstrate relationship between a microorganism and a specific disease.
1 the microorganism must be present in every case of the disease but absent from healthy animals
2 suspected microorganisms must be isolated and grown in pure culture
3 the same disease must result when isolated microorganisms is inoculated into healthy
4 same microorganism must be isolated again from diseased host
Pathogen
Biological asian that can cause disease in a host the host maybe a plan and animal fantasizing microorganisms
Pathogens may be
Cellular as in the case of bacteria fungi and protozoa or they may be non-cellular as in the case of viruses and prions
Pathogens can be divided into
Obligate pathogens that can only survive and reproduce within a host they cause disease before the degree of illness may vary
Accidental or incidental pathogens that can survive without causing disease in a host Many fall into this group living either as part of normal flora and sometimes causing disease or living in other host or reservoirs and causing disease when suitable conditions and susceptible host present themselves
Bacterial pathogens can be divided onto
Opportunistic pathogens seldom cause disease in individuals with intact natural defences and immune system
and primary pathogens can cause infection and disease in otherwise healthy people have intact immune systems
Conditions for opportunistic bacteria
Compromised immune system example from diseases surgery or malnutrition
when competing bacteria have been removed when bacteria enter sites where they are not normally found
Epidemiology
Study of the frequency distribution causes and effects of health and disease in populations
Pathology
Study and diagnosis of disease through the examination of organs tissues and bodily fluids
Virulence
The degree of pathogenicity of an organism and its related to the ability of the organism to invade and damaged tissues of the host
The infectious process
Involves interaction between a pathogen host and the environment
Virulence of an organism depends on
It’s invasiveness
it’s toxicity
the dosage
Thee portal of entry
Spread of infection
Carriers affected and transmit disease yet remain healthy some diseases are contagious during incubation and still other diseases are acquired from animal or environmental sources
Mode of transmission
Direct contact indirect contact a food and waterborne transmission animal vectors transplacental transmission
Portals of entry
Respiratory tract upper and lower airways the mouth the genital area the urinary tract damage skin cuts and Burns
Symptoms of the illness can also promote the transmission of disease for example runny nose diarrhoea cough genital discharge
Bacterial pathogenicity
Bacteria a haploid and reproduce by binary fission the binary fission process does not allow for the exchange of genetic material however but you have develop mechanisms for exchanging genetic information through the transfer of extrachromosomal genetic elements for example plasmids the genes associated with virulence factors often included on extrachromosomal genetic elements and if they are transferred between bacteria the back to receiving the genetic material gain the genes for those virulence factors
Virulence factors
Elements that enhance enhance effective is ability to cause infection and disease adherence factors invasive factors toxins enzymes and antiphagocytic eptic factors bacteria secretion systems
Diagnostic specimen
Tissue samples Blood Urine Cerebrospinal fluid Respiratory secretions Gastrointestinal tract specimen Genital discharge
Diagnostic tools and techniques
Microscopy Cultures Serology Antigen and antibody detection Biochemical analysis Molecular techniques
Treatment
But two infections are usually treated with antibiotics viral infections are treated with anti-viral compounds and fungal infections are treatable antifungal parasites are treated with a variety of antiparasitic drugs immunization with vaccines is an effective way of preventing illness caused by pathogens vaccines work by exposing the body to elements of the pathogen and other in the immune system to become a lot to that pathogen this strengthens the body’s defence against pathogens or if the individual ever becomes infected the immune system is able to attack and destroy the pathogen before it causes disease
Hospital infections nosocomial
Infections which were not present at the time the patient was admitted but instead are acquired while the patient is in hospital these infections become apparent only after the patient has been discharged
Nosocomial infections may be acquired from
Exogenous sources from other patients or environment
Endogenous from diff site within same patient
Most common nosocomial infections are of the urinary tract surgical site or pneumonia
Infection controlled by sanitation of surfaces hand washing or changing gloves between patients changing gown regularly sterilisation or equipment and isolation of infective patients
