Microbiology is the branch of science that analyzes the disease causing microorganisms and the diseases that they cause. Microscopic organisms such as bacteria, viruses, fungi, yeasts, and protozoans are included in its context. Those factors with different shapes and sizes are the cause of a number of diseases in animals. Most of those diseases also spread to human and they are called as zoonotic diseases.
Microorganisms infect animals in different ways. The main infection ways are digestion, respiration, circulation, urogenital system and skin. Each kind of food and water, contaminated with microbes, gets into the body with the digestive tract. The microbes which gets out through the respiratory tract of the sick animals are inhaled by other animals and they spread. The microbes can get into the circulatory system through an object that pricks to the skin from outside or the stinging flies. As a result of the mating, sick animals might infect the healthy ones. Especially, microorganisms showing affinity to the skin cause infection in the skin as a result of the skin contact.
The accurate diagnosis of the diseases that microorganisms cause is performed in our laboratory. The versatile analysis of the samples sent to our laboratory is made. The clinical findings are too much essential. In the diseases caused by bacteria and fungi, the colony identification can be done with both light microscopy and inoculation to various medium.
It is the sub-scientific branch of the microbiology, analyzing the bacteria. The analysis of microorganisms, production of them in different culture mediums and staining are within the context of bacteriological researches. Bacteria isolation from various materials (nose-throat swab, urethral discharge, urine and so on) is being done in our laboratory. The mostly isolated bacteria since the foundation of our laboratory;
Staphylococcus aureus: Bacteria found in Staphylococcus genus are viewed as gram positive coccus with the gram staining. They can be found as single, double and quadruple cells, they can form chains consisting of three or four cells and they can form structures such as irregular bunch of grapes (Staphylo: bunch of grapes, coccus: the grain). They are immobile, non-spore forming, mainly catalase positive, oxidase negative and without capsule and they are facultative anaerobe. Staphylococci which grows on the blood agar in 24 hours form colonies having hemolysis zone and golden color. Since they show rapid resistance to antibiotics, to choose the appropriate antibiotic, antibiogram sensitivity test should be made. The clinical pictures that Staphylococcus aureus causes; skin infections (surgical or non-surgical wound infections, abscess and so on), bacteremia/sepsis, septicemia and endocarditis, organ infections and toxins (Peeled skin syndrome), arthritis, osteomyelitis, nose, nasopharynx, skin, vagina inflammation and so on.
Escherichia coli: Since there is a compatible relationship between Escherichia coli, which is a normal member of intestinal flora, and the host organism, bacteria normally do not cause any diseases. However, if they pass to the environment, which can be another organ in the same organism (such as passing to the bladder with the urinary tract infection) or can be the intestine of another host organism, the factor can be a disease cause. Among those disease, primarily diarrheal diseases might occur as well as urinary tract infection, meningitis, mastitis, septicemia and gram-negative pneumonia. Escherichia coli was isolated from various biological materials in poultry, cattle, horse and pets in the studies conducted in our laboratory.
Pseudomonas aeruginosa: They are gram negative, asprogenic or in the structure of non-capsule bacillus or coccobacillus. Pseudomonas aeruginosa does not ferment the carbohydrates, while it decomposes a number of sugar oxidatively, it does not affect maltose. The primary clinical pictures of Pseudomonas aeruginosa; respiratory tract infections, endocarditis, central nervous system infections, urinary system infections, ear and eye infections. More uncommon when compared to those clinical pictures, it causes gastrointestinal system infections, bone joint infections, skin and soft tissue infections and sepsis.
Proteus sp.: Those factors which are gram negative, in basil shape, but might show pleomorphic feature, are mobile and they do not cause hemolysis in the blood agar and they do not decompose lactose. The most significant species are Proteus mirabilis, Proteus vulgaris and Proteus myxofaciens. In the studies we conduct in our laboratory, Proteus sp., which is an important contamination factor, were isolated from clinically suspicious urinary system infections and otitis cases in dog and cats. Also, they are known to cause endometritis and urogenital system infections in horses and mastitis and endometritis in cattles.
Salmonella sp.: They are gram negative, short and in basil shape. Salmonella, which are mostly shown separately in the stained slides, are asprogenic and non-capsule. They can reproduce in the medium easily. They cause abortion in horses and sheeps. Except for the special Salmonella infections in animals, some Salmonella species cause infections similar to the gastroenteritis in humans, in a number of animal species including primarily cattle, sheep, goat, horse, cat and dog.
Enterococcus sp. infections: They are gram positive cocci forming single, double or short chains. They are facultative anaerobe bacteria. They are catalase negative since they do not have cytochrome enzymes. They do not form gas from glucose. Enterococcus colonies have large, grey, bright and steamy appearance in blood agar and they are beta-hemolytic or non-hemolytic. They cause abortions, genital system infections and infertility in horses. They cause abortion and mastitis in cattles.
Streptococcus sp. infections: Streptococci are the factors which are gram positive, round shaped, forming series in chains, immobile, asprogenic, with capsule and cause a number of diseases in humans and animal locally or generally. Streptococci can live in the mucus membranes and gastrointestinal system of animals normally. However, the pathogenic ones generally show host and tissue preference. There are 3 different groups, namely beta or hemolytic, alpha or viridans and non-hemolytic.
In our laboratory; Beta-hemolytic streptococci are the ones mostly isolated. Streptococcus pyogenes, Streptococcus agalactiae (Cattle Mastitis factors), Streptococcus canis (In cat and dogs) and Streptococcus equi (Ruam factor) are included in this group. Besides those, Viridans Streptococci (Streptococcus uberis, Streptococcus bovis, and Streptococcus dysgalactiae) are also isolated.
Note: Please refer to the Microbiology, Serology-Virology section included in “Laboratory Guide of the Veterinary Clinician” for the microbiology samples and tests.