Infection PHC
Definition - The invasion and growth of germs in the body. The germs may be bacteria, viruses, yeast, fungi, or other microorganisms. Infections can begin anywhere in the body and may spread all through it. An infection can cause fever and other health problems, depending on where it occurs in the body.
(शरीर में कीटाणुओं का आक्रमण और वृद्धि। रोगाणु बैक्टीरिया, वायरस, खमीर, कवक या अन्य सूक्ष्मजीव हो सकते हैं। संक्रमण शरीर में कहीं भी शुरू हो सकता है और पूरे शरीर में फैल सकता है। एक संक्रमण बुखार और अन्य स्वास्थ्य समस्याओं का कारण बन सकता है, यह इस बात पर निर्भर करता है कि यह शरीर में कहां होता है।)
inflammation - Inflammation is part of the complex biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or irritants, and is a protective response involving immune cells, blood vessels, and molecular mediators.
The function of inflammation is to eliminate the initial cause of cell injury, clear out necrotic cells and tissues damaged from the original insult and the inflammatory process, and initiate tissue repair.
The five cardinal signs of inflammation -
Incubation peroid - : the period between the infection of an individual by a pathogen and the manifestation of the illness or disease it causes.
BACTERIA - Robert Hooke who described the fruiting structures of molds in 1665 and Antoni van Leeuwenhoek who is credited with the discovery of bacteria in 1676.
study of bactria called bactriology.
-Bacteria are unicellular free living organisms without chlorophyll having both DNA and RNA.
- They are capable of performing all essential processes of life, e.g. growth,
metabolism and reproduction.
- They have rigid cell wall containing muramic acid (Muramic acid is an amino sugar acid. In terms of chemical composition, it is the ether of lactic acid and glucosamine. )
-Prokaryotes cell present in bacteria.
Size of bacteria: Most of bacteria are so small that their size is measured in terms of micron.
1 micron (μ) or micrometre (μm) = One-thousandth of millimetre.
1 millimicron (mμ) or nanometre (nm) = One-thousandth of micron.
1 Angstrom units (Å) = One-tenth of nanometre.
Generally cocci are about 1 μ in diameter and bacilli are 2 to 10 μ in length and 0.2 to 0.5 μ in width.
Shape of bacteria: On the basis of shape, bacteria are classified as under:
(A) Cocci (from kakkos, meaning berry):They are spherical. On the basis of arrangement of individual organisms, they are described as
staphylococci (clusters (group) like bunches of grapes), eg - cellulitis, mastitis,
streptococci (arranged in chains), e g - Rheumatic Fever, scarlet fever.
diplococci (forming pairs),eg -pharyngitis, tracheitis, sinusitis, bronchitis, and otitis.
tetrads and sarcina are cocci arranged in groups of four and cubical packet of eight cell respectively.
eg - endocarditis,UTI.
(B) The cylindrical or rod shaped organisms are called bacilli (from baculus, meaning rods).
They are of following types :
1. In some of the organisms length may approximate the width of the organisms.
These are called coccobacilli, e.g. brucella. due to contact with animals.
2. Chinese letter arrangement is seen in corynebacteria.
3. Vibrio: These are comma shaped, curved rods and derive the name from their characteristic vibratory motility. eg- cholera.
4. Spirochaetes (from speria meaning coil, chaete meaning hair). They are relatively longer, thin, flexible organisms having several coils. eg syphilis, yaws(tropical skin disese), Lyme disease, .
5. Actinomycetes (actis meaning ray, mykes, meaning fungus) are branching filamentous
bacteria, so called because of resemblance to radiating sunrays eg eg -found in the nose and throat..
6. Mycoplasma are organisms which lack cell wall and so do not possess a stable morphology.
They are round or oval bodies with interlacing filaments. eg - pneumonia,PID.
structure of the bactria -
VIRUS -
Viruses are unicellular,-Prokaryotes de cell present in bacteria. ultramicroscopic particles containing either RNA or DNA, which reproduce inside living cells, pass through filters and are covered by a protein coat.
study of the virus called virology Virulent, from Latin virulentus ('poisonous'), dates to c. 1400. A meaning of 'agent that causes infectious disease' is first recorded in 1728, long before the discovery of viruses by Dmitri Ivanovsky in 1892.Martinus Beijerinck is often called the Father of Virology
The origin of virus is not known.
Size: Viruses vary widely in size. The largest among them is pox virus measuring about 300 nm. The smallest viruses is foot and mouth disease virus measuring 20 nm.
Shapes: Some viruses have characteristic shape,
e.g. rabies virus has bullet shape,
pox viruses are brick-shaped,
tobacco mosaic virus is rod-shaped,
bacteriophage has head and tail, like sperm,
influenza or polio viruses a respheroidal . (round)
structure of the virus -
FUNGI ---
Fungi and yeasts constitute eumycetes (FUNGI). These eukaryotes lack chlorophyl pigments.
Heinrich Anton de Bary is known as the father of Mycology.
Morphologically the fungi may be either simple, oval cells or long, tubular, septate hyphae showing true lateral branching.
The yeasts and fungi need organic compounds as nutrients.
Their role in nature appears to be as scavanger, i.e. breaking down the complex carbohydrates and proteins of dead bodies of other organisms.
Needless to mention that only a few of them are pathogenic.
In many ways, fungi have been of service to man, as in the making of bread, fermented drinks, cheese, antibiotics, etc.
fungal disese -
- athlete's foot.
- jock itch.
- ringworm.
- yeast infection.
- onychomycosis, or a fungal infection of the nail.
Poor hygiene, warm climate, poor sanitation and nonavailability of safe water encouragethe parasitic infection and provide predisposing factors.
A parasite is an organism which takes its nourishment from another host without giving anything in return. The parasites include protozoa and helminths. When a parasite lives in its host like tapeworm, malarial parasite, it is known as endoparasite and is said to cause an infection.
FACTORS AFFECTING GROWTH AND DESTRUCTION OF MICRO-ORGNISM-
food, acidity, time, temperature, oxygen and moisture.
Difference between pathogenic and non-pathogenic bacteria
| Pathogenic Bacteria | Non Pathogenic Bacteria |
| Inflicting Diseases | |
| Can cause diseases | Do not cause any disease |
| Effect | |
| They can be harmful | They are useful |
| Type of symbiotic relationship | |
| Parasitism | Commensalism |
| Virulence genes | |
| Present in genome | Absent |
| Where are they found? | |
| Occupy the body cells | Found outside the body cells |
| Production of toxins | |
| Yes, they produce | No, they do not produce |
| Formation of colonies | |
| Yes, they produce colonies in tissues | No, they do not produce colonies |
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