Bacteria Definition: It's a group of micro-organisms.They're typically small cells of about 1 micron in transverse diameter. Structurally there is a protoplast, containing cytoplasmic and nuclear material which isn't seen by an ordinary microscope, within a limiting cytoplasmic membrane and a supporting cell wall. Other structures such as flagella, fimbriae and capsules may also be present. Individual cells may be spherical, straight or curved rods or spirals; they may form chains or masses and some show branching with mycelium formation.
Most of the opportunistic microorganisms are found in unsterilized sites such as gut, throat, skin, urinary tract as norm flora. When the defense mechanism of the host id weakened or become defective, they become harmful by invading deeper organs thus causing disease called opportunistic infections. READ MORE>>
Haemophilus influenzae was so named because of a supposed relationship to influenza and was designated haemophilic in virtue of its inability to grow-on culture medium without the addition of whole blood, or certain growth-promoting substances, termed X and V, present in blood. These growth factors, however, are not restricted to blood, but are present also in certain vegetable tissues.
If the term haemophilic were used in a broad sense to designate organisms which require blood for their growth it would embrace a number of heterogeneous species, and the generic term Haemophilus is therefore restricted to those organisms which are dependent on one or both of the growth factors required by Haemophilus influenzae. READ MORE
The mycobacteria, or acid-fast bacilli, have distinctive biological characters differentiating them from most other microorganisms. They belong to the group of organisms that includes, and appear related to the pathogenic actinomycetes and nocardiae. Because of a waxy material in their cell walls the mycobacteria are not easily stained but treatment with hot carbol fuchsin allows impregnation by the dye which is retained despite attempts to remove It with acid or alcohol. The mycobacteria are thus called 'acid-fast' organisms. Another characteristic feature is the very slow growth of the pathogenic mycobacteria or even failure to grow, e.g. Mycobacterium leprae, on artificial culture media. .... READ MORE
LEPTOSPIRA: THE CAUSE OF LEPTOSPIROSIS.
Throughout the world there exists a group of spiral microorganisms that are characterized by their slender appearance, numerous coils, hooked ends and active motility. They constitute the genus Leptospira. Many different types of these organisms exist, some are saprophytic and harmless to man and animals, whilst others are parasitic and potential pathogens. The parasitic leptospires are normally carried in the kidneys of rodents and other small mammals but in some parts of the world domestic animals for example dogs, pigs, goats, cattle and other vertebrates, wading birds, snakes, frogs and tortoises have all been found to be infected although most of them probably play a minor role as carrier hosts. The organisms apparently cause no harm to their normal hosts, but if they are transmitted accidentally to other animals or to human beings, they may give rise to clinical infection, leptospirosis, with disease manifestations that vary from the relatively mild to extremely severe. The most virulent types may cause spirochaetal jaundice. READ MORE