Bacterial Infection Easy Review from Biology Questions and Answers Our Biology Book Study the Bacterial Infections Here 1. What are some human diseases caused by bacteria and what are their respective modes of transmission? The main human bacterial infections transmitted by respiratory secretions (sneezes, cough) and saliva drops are: bacterial pneumonias, tuberculosis, whooping cough (pertussis), diphtheria, bacterial meningitis. Main bacterial diseases transmitted by blood or sexual contact are: gonorrhea, syphilis. Main bacterial diseases transmitted by animal vectors are: bubonic plague, endemic typhus, leptospirosis. Some bacterial diseases transmitted through fecal-oral route and contaminated food are: cholera, typhoid fever. Other important bacterial infections: Hansen's disease, possibly transmitted by saliva drops and contact with injured skin and mucosae; trachoma, eye disease transmitted by ocular secretions; tetanus, transmitted when the etiological agent enters the body through skin wounds. Bacterial Infection - Image Diversity: bacteria 2. What is tuberculosis? How is the disease transmitted? Is there treatment for tuberculosis? Tuberculosis is a disease caused by the Mycobacterium tuberculosis, bacteria which attack other organs of the body but mainly the lungs leading to respiratory insufficiency. Before 1940, tuberculosis had already been one of the main causes of death in the USA and Europe. The disease can remain latent, without manifestation for several years and even throughout the life. Tuberculosis is highly contagious, transmitted by air route through sneezes and coughs from a person with the active disease. Transmission is common between members of the same family or even in work environments. The disease today has treatment with efficient antibiotics. Generally, the patient receives three different drugs for several months until healing is complete. There are however some strains of multiresistant TB bacteria that emerged by mutation and natural selection due to the intense use of antibiotic drugs mainly in hospitals and treatment facilities; in these cases the treatment is more difficult. Bacterial Infection - Image Diversity: tuberculosis 3. Is there vaccine against tuberculosis? The vaccine against tuberculosis is called BCG (bacillus Calmette-Guérin). BCG is not used in some countries where tuberculosis is not so prevalent because it can distort later diagnostic studies of the disease; in other countries, like Brazil, it is obligatory for children. The vaccine is made of attenuated TB bacteria. 4. Are all pneumonias caused by bacteria? Pneumonia is the generic name of inflammation of the lungs. Besides bacterial pneumonias, there are pneumonias caused by virus, fungi, toxic pneumonias, etc. Bacterial Infection - Image Diversity: pneumonia 5. What is Hansen’s disease (etiological agent, mode of transmission, clinical manifestations and prevention)? The etiological agent of Hansen’s disease is bacteria called Mycobacterium leprae. The mode of transmission is not yet totally known but it is believed that respiratory secretions and saliva drops can spread the disease. Hansen’s disease is a chronic disease (slow progression) that generally attacks the skin and the peripheral nerves although other areas of the body can be affected. In the skin nodules, reddish spots, thickening of the dermis and lack of sensitivity appear; the mucosae, especially the nasal mucosa, may be injured and also the viscera may be affected. The main form of prevention is information, since there is available treatment; infected people should, as soon as possible, look for health services for evaluation and treatment of the disease. In the past Hansen’s disease was called leprosy. Bacterial Infection - Image Diversity: Hansen's disease 6. What is the etiological agent and the main manifestations of cholera? Cholera is a bacterial disease caused by the Vibrio cholerae. The disease is transmitted by fecal-oral route and the main mode of transmission is ingestion of contaminated water or food. It is most prevalent in places that lack adequate sanitary conditions. Inside the human gut the cholera vibrion releases toxins called enterotoxins. The infection can cause intense diarrhea, vomiting, dehydration and even death in more severe cases. Bacterial Infection - Image Diversity: cholera 7. What is meningitis? Meningitis is the generic name given to inflammation of the meninges, membranes that cover the central nervous system. Meningitis can have several causes (infectious, toxic, traumatic, neoplastic infestation, autoimmune). Bacterial infections caused by meningococcus, haemophilus, pneumococcus or by tuberculosis bacteria are severe and contagious. The main symptoms of bacterial meningitis are high fever, nuchal rigidity, intense headache, vomiting and sometimes convulsions. The disease should be treated with antibiotics. Bacterial Disease - Image Diversity: meningitis 8. What is syphilis? Syphilis, also known as lues, is a disease caused by the bacteria Treponema pallidum. Before the discovery of penicillin, syphilis was a fatal disease. Today the use of antibiotics can cure the disease completely. Patients with primary syphilis present a single and painless wound in the skin, sometimes called chancre, in the region where the treponema has penetrated; the chancre is highly infective. Syphilis is one of the main STDs, sexually transmitted diseases. Generally the chancre develops in the penis, vagina, anus, hands or mouth, and the bacteria is often transmitted by sexual contact. Later syphilis develops into systemic diseases, secondary and tertiary syphilis. Syphilis can also be transmitted by blood transfusions, accidents with contaminated objects and vertically from the mother to the child (congenital syphilis). It is very important for patients with the disease to seek treatment as soon as possible and to undergo tests to look for other STDs, like HPV and HIV infections. 9. What is an antibiogram? Antibiogram is a laboratory test intended to guide the choice of adequate antibiotic to treat a given bacterial infection. In the antibiogram cultures of bacteria obtained from tissues contaminated by the infection under study are submitted to the action of different antibiotics. After some time it is verified which of the antibiotics were successful in interrupting the bacterial growth or in killing the bacterial population. The antibiogram is very important to avoid exaggerated and inefficient use of antibiotics and the emergence of multiresistant bacteria. Bacterial Infection - Image Diversity: antibiogram