Microbiology Lecture - Infections of the Alimentary System

Lancaster Bio 240 Revised Winter 2006 1 Microbiology Lecture - Infections of the Alimentary System (Chapters 25) I. Introduction A. The intact epithelium of the digestive system (figure 25.1) is also part of the First Line of Defense. B. Normal Flora 1. Upper Alimentary System a. Most of the flora occurs in the mouth; bacteria and other microbes are sparse in the esophagus and generally absent in an empty stomach. Those in the mouth are generally transients. b. Resident mouth flora primarily belongs to the genus Streptococcus with colonization locations depending on species. c. These bacteria are very numerous especially in dental plaque. 2. Lower Alimentary System a. Bacteria (some Gram negative bacilli, streptococci, lactobacilli) and yeasts (Candida albicans) are relatively sparse in the small intestine. b. The large intestine however, contains many bacteria from @ 300 species (making up about 1/3 of the weight of feces). c. The primary species are: Bacteroides, and the coliforms (e.g., Esherichia coli, Enterobactor, Klebsiella, Proteus). d. These bacteria are beneficial in that they outcompete potential pathogens and play a role in vitamin metabolism. e. Yeasts (e.g., Candida albicans) and other bacteria that can cause disease (e.g., Clostridium difficile; antibiotic associated colitis or pseudomembranus colitis which can be life-threatening) are also present. C. Infections of the Upper Alimentary System (particularly of the mouth are caused by normal flora) 1. Dental caries are the most common infectious disease and the main reason for tooth decay. Once pain starts the disease is well developed. a. Cause- primarily S. mutans and closely related species. There can be up to 100 billion bacteria/g of plaque (they are strict anaerobes). Foods with sugars are involved too, sugars drop the pH resulting in the destruction of the enamel of the teeth. b. Dx- symptoms, clinical manifestations c. Tx – fillings tooth extraction etc. e. Prevention - dental hygiene (home and twice yearly professional cleanings), diets low in sugar, use of fluoride 2. Periodontal disease (Table 25.1) is a chronic inflammatory process of the gums and other tissues of the mouth. It develops over years and is one of the primary causes of tooth loss. It is mostly asympomatic but bleeding gums, sensitivity, bad breath, and loose teeth occur in the later stages. The gums begin to recede leading to the formation of dental caries on the roots of the teeth. By age 65, 90% of people have periodontal disease. Brushing, flossing, professional cleanings help treat and prevent this so that the teeth can be saved for as long as possible. Trench mouth is a severe acute infection of the gums. Symptoms include fever, bleeding gums, pain, odor __________________________________________________________________________________________________________ Lancaster Bio 240 Revised Winter 2006 2 3. Herpes simplex (figure 25.9 and Table 25.3) a. Cause - Herpes simplex virus (usually type 1) b. Herpes often begins in childhood and produces fever and vesicles that ulcerate. The infection then becomes latent in sensory with sporadic recurrences (e.g., cold sores, fever blisters, herpes simplex labialis). It is widespread infecting up to 90% of people and causing recurrent infections in 20-40% of the people in the US. Symptoms include tingling, itching, burning or painful sensations. The blisters usually heal within 7-10 days. Occasionally, these oral infections lead to encephalitis. Sometimes, herpetic whitlow (a skin infection) occurs due to contact of open skin with saliva. Also infections of the eye occur resulting in corneal blindness (in some people). It is transmitted by close direct contact or by indirect contact with contaminated inanimate objects (the virus can live for up to several hours outside of the host) c. Dx - symptoms, tissue culture d. Tx - Acyclovir for active infections e. Prevention- sun screens help stop UV light and reduce relapses of herpes simplex I 4. Mumps (Table 25.4) a. Cause - a paramyxovirus b. Mumps begins with fever, loss of appetite, and a headache. These symptoms are followed by swelling of one or both parotid glands with difficulty in talking and swallowing. Symptoms usually last about a week. Involvement of the testis (orchitis) and ovaries can occur in males and females past puberty. Spread by saliva or droplet nuclei that are breathed in. Humans are the only natural host. Serious consequences are rare, they include: sterility, deafness, meningitis, and encephalitis. Although mumps does not result in birth defects, it often causes miscarriage if the infected person is pregnant. Due to vaccinations, mumps is rare in the U.S. (see figure 25.10) c. Dx- tissue cultures and serology d. Tx- symptoms, it usually is resolved in a week e. Prevention - vaccination ___________________________________________________________________________________________________________ Lancaster Bio 240 Revised Winter 2006 3 5. Helicobacter pylori Gastritis (Table 25.2) a. Cause - Helicobacter pylori (see figs. 25.7 and 25.8) b. This bacterium attaches to mucus-producing cells of the stomach resulting in a decrease in mucus production. This can lead to the formation of ulcers (65-80% of gastric ulcers and 95% of duodenal ulcers) or cancer and most people are asymptomatic until the infection is complicated by ulcers or cancer. Localized abdominal pain, tenderness, and bleeding are symptoms of the complications. It produces urease that converts urea to ammonia resulting in a decrease in pH. This infection is common and the incidence increases with age. T c. Dx - urease in stomach tissue, culture and isolation, and microscopy d. Tx - bismuth compounds and antibiotics (two kinds) e. Prevention – 6. Esophageal infections occur in AIDS patients and other immunocompromised individuals D. Lower Digestive System Infections 1. Cholera Table 25.5 a. Cause Vibrio cholerae b. The symptoms of cholera include vomiting and the production of a secretory diarrhea (copious amounts of watery feces that are odorless and contain mucus AKA “rice-water stools”). World-wide the morbidity is 100,000 cases/year. The severe diarrhea (fluid loss can be up to 20 liters/day) can easily result in dehydration and then death (untreated mortality 55%) however, with prompt fluid and electrolyte replacement, mortality is decreased to 1%. The symptoms are the result of cholera toxin. Fecally contaminated water is the most common source of infection. Seven pandemics of cholera have occurred in the past (one of these relatively recently in Peru). In addition, a new strain emerged in India in 1992, that spread rapidly but fortunately has not resulted in a pandemic. c. Dx - symptoms, dark-field microscopy, culture and isolation d. Tx - fluid and electrolyte replacement and antibiotics e. Prevention - handwashing, proper sewage disposal, water purification, adequate washing or cooking of foods, vaccination (only 50% effective). __________________________________________________________________________________________________________ Lancaster Bio 240 Revised Winter 2006 4 2. Shigellosis (Table 25.6) a. Cause Shigella species (e.g., S. dysenteriae) b. This dysentery is characterized by crippling abdominal cramps and diarrhea (watery stools with mucus and blood). There are about reported 21,500 cases in the US/year (but probably much higher due to unreported cases) and about 150 million/yr world-wide). Toxins are involved which produce a fever, and inflammation and erosion of the large intestine epithelium. One toxin may cause neurological symptoms and coma. Hemolytic uremic syndrome may also occur (when the strain produces shiga toxin). The ID is low and it is highly communicable. c. Dx - culture and isolation d. Tx - antibiotics e. Prevention - No vaccine, but handwashing and increased sanitation. 3. Salmonellosis (non typhoidal enteric fever, food poisoning, and gastroenteritis) Table 25.9 a. Cause Salmonella species (e.g., S. enteritidis, and S. typhimurium; taxonomic changes have affected species names). b. These zoonotic infections are acquired from eating foods such as undercooked meats and eggs. There are @ 47,500 reported cases each year in the US and the actual number may be as high as 2 million/year. Symptoms: diarrhea, abdominal pain and vomiting. A few strains cause a more serious disease (entercolitis) that can lead to death due to intestinal rupture. c. Dx - culture and isolation d. Tx- usually self-limited (about 1-4 days) e. Prevention - adequate food handling and cooking. 4. Typhoid fever. Read about Typhoid Mary. a. Cause Salmonella typhi b. Humans are the only reservoirs for this organism (under natural conditions). Typhoid is a severe systemic disease that begins in the intestine and progresses to septicemia. Symptoms include: fever, diarrhea, abdominal pain, hemorrhage, and abscess formation. Untreated mortality is 10-15%. It is transmitted by fecally contaminated food and water. Healthy carriers may shed as many as 10 billion bacilli/g of feces. c. Dx - serology and culture and isolation d. Tx – antibiotics, in carriers, removal of the gallbladder may be necessary (where the bacteria multiply) e. Prevention - handwashing, adequate cooking etc., two types of vaccines give partial protection _________________________________________________________________________________________________________ Lancaster Bio 240 Revised Winter 2006 5 5. Escherichia coli gastroenteritis a. Cause - An enteropathogenic strain of Escherichia coli (Table 25.8) b. Symptoms vary depending on the virulence of the species causing the infection (see Table 25.7) and include vomiting and diarrhea (mild to severe with some producing shiga toxin). These strains produce toxins and many patients develop hemolytic-uremic syndrome that can be fatal in the very old and the very young. c. Dx - culture and isolation and serology d. Tx - fluid replacement, antibiotics and if necessary dialysis e. Prevention - handwashing and adequate cooking of food. f. Campylobactor jejuni is also one of the most common causes of bacterial gastroenteritis worldwide (over 2 million cases in the US each year). The disease is usually self-limited but fluid replacement may be necessary and can be fatal to the elderly or immunocompromised. 6. Food poisoning e.g., Staphylococcal enterotoxicosis a. Cause - Several bacterial species primarily Staphylococcus aureus. b. Food poisoning is the result of the consumption of toxins produced by bacteria found in the food (some toxins are heat stabile so cooking does not help). Thus the bacteria do not actually cause an infection, but the toxins make you sick. Symptoms include nausea, vomiting, and diarrhea. The disease is usually self-limited, but it can result in dehydration and thus have negative consequences for the very young and the very old. c. Dx- symptoms d. Tx- symptoms e. Prevention - keep foods at adequately low temperatures. Avoid foods that have set out at room temperature. Adequate handwashing. f. Clostridium perfringens (which also causes gangrene) is also a common cause of food poisoning. It is also self limited. 7. Viruses can also infect the lower alimentary system or the accessory organs of the digestive tract. For example hepatitis A and hepatitis B infect the liver (see Table 25.12). HAV is spread primarily through fecal contamination of hands, food or water. Most cases are mild or asymptomatic, but some can be very serious. HBV is more severe and may result in death due to liver failure. This disease is spread mainly be blood, blood products or semen. There are an estimated 240,000 new cases of this disease diagnosed in the US each year. There are vaccines for hepatitis from HAV and HBV. Hepatitis C virus is another cause of hepatitis and this one is also spread by blood, blood products and tissue transplants. It is the most common blood-borne infection in the U.S. However, there is no vaccine. __________________________________________________________________________________________________________ Lancaster Bio 240 Revised Winter 2006 6 8. Viral gastroenteritis is also common (2.7 million cases in the US each year). The symptoms include nausea, vomiting and diarrhea. Rotaviral gastroenteritis is most common in infants and children and although most recover, there are 600,000 deaths attributed to rotavirus worldwide each year. Noroviruses virus gastroenteritis is common in children and adults causing 23 million cases of gastroenteritis/year. The symptoms usually last between 12 and 60 hours. 9. Giardiasis a. Cause - Giardia lamblia (figure 25.22 and Table 25.13) b. This is one of the common types of traveler’s diarrhea and is very common in economically undeveloped areas; incidence 10% Many people are asymptomatic, but others develop diarrhea, bloated abdomens, and gas. Nutritional deficiencies can occur in infected children. c. Dx - direct exam of feces, serology d. Tx - antiparasitic drugs e. Prevention - boil drinking water (if not chlorinated or filtered). 11. Amebiasis or sometimes Amebic dysentery (Table 25.16) a. Cause - Entamoeba histolytica (fig. 25.24) b. Humans are the primary hosts (including chronic healthy carriers). Morbidity may be as great as 400 million world-wide. Mortality about 30,000 per year worldwide (mostly in crowded areas where unsanitary living conditions are common). The infection is usually asymptomatic or mild but in clinical cases, the amoebas secrete enzymes that dissolve the tissues of the intestine. The symptoms are then diarrhea with bloody, mucus-filled stools, abdominal pain, fever, fatigue, and weight loss. Serious complication such as hemorrhage and liver abscess formation can occur. c. Dx- direct exam of feces d. Tx - antiparastic drugs e. Prevention - hygiene and sanitation, avoid local water while traveling. 12. Other parasites can cause diarrheal disease. a. Cryptosporidium is an intestinal parasite causing cryptosporidiosis (a zoonosis). If is often asymptomatic, or with short lived symptoms of a “stomach flu”, but in immunocompromised individuals it can cause a life-threatening diarrhea (as many as 25 stools/day with a loss of up to 17 liters of fluid/day) that can last for months. There is no cure. See Table 25.14 b. Parasitic worms cause infestations in many persons worldwide. Ascaris lumbricoides is thought to infect @1/4 of the world’s population (but a small infestation may go unnoticed). Enterobius vermicularis (pinworms) is the most common worm disease of children in the temperate zone. This worm causes itching and discomfort at night when the females come out to lay eggs. Trichinella spiralis is acquired from eating undercooked meat. The females live in the intestine, but the larvae encyst in muscle tissue. Tapeworms are acquired by eating contaminated undercooked beef (Taenia saginata), pork (T. solium) or fish (Diphyllobothrium latum). _________________________________________________________________________________________________________ Lancaster Bio 240 Revised Winter 2006 7 Infections of the Genitourinary System (Chapter 26) I. Introduction A. In general there are no microbes found in the upper part of the urinary tract and urine is generally sterile (due to low pH, salt and urea). But the lower part of the urethra does have normal flora. These organisms include: Lactobacillus, coagulase-negative Staphylococcus, diphtheroids, Hemophilus, Streptococcus, and Bacteroides. B. In females, the normal flora and susceptibility to infection varies with the ovarian cycle. When estrogens are present, the vagina is more acidic (due to the metabolism of glycogen by Lactobacilli) and thus less susceptible to infection. II. Infections of the Urinary System (Figure 26.1) A. Bladder infections are more common in women and are often related to sexual activities. B. Bladder infections (cystitis) Table 26.1 1. Causes include enterobacteria (like E. coli), Staphylococcus saprophyticus, Pseudomonas, and Enterococcus. 2. Cystitis in women is often accompanied by dysuria (pain or burning during urination) and may lead to kidney infections (pyelonephritis). Symptoms of cystitis include: burning sensation during urination, urgency, frequency, and an odor. Glomerulonephritis AKA Bright’s Disease causes inflammation of the kidneys that leads to damage in some cases it even leads to kidney failure. This is a common nosocomial infection that is an important source of fatalities (especially when it spreads to the kidneys causing pyelonephritis with fever, chills vomiting, back pain, blood in urine etc.). Women are predisposed to UTIs (urinary tract infections) due to their short urethras, sexual intercourse, and use of diaphragms. Older men become more susceptible as their prostates enlarge. The presence of a catheter also increases susceptibility. 3. Diagnosis- urinalysis, culture and isolation 4. Treatment- antibiotics 5. Prevention- drinking plenty of fluids and for women and girls wiping front to back. C. Organisms that can be involved in these infections include: Escherichia coli, Enterobacter aerogenes, Proteus sps., Pseudomonas aeroginosa, staphylococci, and enterococci; note that many of these organisms are normal flora of the intestines). ___________________________________________________________________________________________________________ Lancaster Bio 240 Revised Winter 2006 8 C. Leptospirosis Table 26.2 1. Cause Leptospira interrogans 2. Leptospirosis is a zoonosis and is spread to the urinary system from the bloodstream. The bacterium enters the body through mucous membranes or through breaks in the skin. Many cases are asymptomatic, but the mortality rate for more severe cases when untreated can be as high as 30%. The onset is abrupt and includes headache, fever, chills, redness of the eyes. Most recover, but in some people, the symptoms reoccur and they may have bleeding from various sites, confusion and organ damage. The organism is excreted in the urine of non-human animals. Like some of the other bacterial diseases, the Jarisch-Herxheimer reaction can occur where symptoms worsen about 4-6 hours after treatment is begun due to the release of antigens from organisms lysed be the medication. 3. Diagnosis- culture and isolation 4. Treatment- antibiotics (e.g., tetracycline) 5. Prevention- avoid contact with non-human animal urine. III. Infections of the Genital tract (Figure 26.10). Note that not all of these infections are sexually transmitted diseases. These infections are also more common, in general, in females. Note to that the US has a higher incidence of STDs than other industrialized countries. A. Gonorrhea Table 26.10 and figures 26.8 and 26.9 1. Cause - Neisseria gonorrhoeae (see figure 20.9) 2. Humans are the only reservoirs of infection. It is among the most prevalent of the STIs (sexually transmitted infections) but the incidence has been decreasing over the last 15 years (there are about 342,000 cases/year). Infections can also occur in the throat or anus. In males, the infection is often symptomatic causing painful urination and pus formation (see figure 20.10) and can be selflimiting. In women the disease can be asymptomatic for a long time with complications: PID (leading to sterility or ectopic pregnancies) and eye infections in newborns (ophthalmia neonatum). Untreated infections in males can also lead to sterility due to orchitis and also lead to UTIs. Systemic infections (disseminated gonococcal infection, DGI) can occur. Antibiotic resistance is increasing in this organism. 3. Dx - in males a Gram stain on material obtained from the urethra, in females culture on special media. 4. Tx - antibiotics 5. Prevention – monogamy, safe sex (consistent and proper use of condoms), abstinence __________________________________________________________________________________________________________ Lancaster Bio 240 Revised Winter 2006 9 B. Nongonococcal urethritis mostly chlamydial infections Table 26.9 1. Cause - Chlamydia trachomatis 2. Humans are the only reservoirs. Like gonorrhea, there are infections of the genital tract as well as of the eye (acquired during birth or interestingly enough from non-chlorinated swimming pools). This STI is the most common with 4 million cases/year. In males, the manifestations are a nongonococcal urethritis. In females who are symptomatic, a cervicitis occurs which is characterized by vaginal discharge, endometritis, in some cases painful urination, abnormal vaginal bleeding, and abdominal painand also PID 3. Dx - tissue culture or serological testing 4. Tx - antibiotics 5. Prevention – monogamy, safe sex (condoms) and abstinence 6. There are other organisms that cause nongonococcal urethritis C. Syphilis Table 26.11 and figures 26.12-26.16 1. Cause - Treponema pallidum 2. Humans are the only natural reservoirs. Syphillis is called the great imitator due to the similarity between some of the symptoms and other diseases. The risk of infection when having intercourse with an infected person is 12-30% and transmission usually involves sexual intercourse, but it can be transmitted (rarely) by kissing. However, there has been a dramatic decrease in new cases since 1990 (from 100 new cases/100,000 to 2.6 cases/100,000). Less commonly, it can be passed from mom to fetus in utero causing congenital syphilis and by blood transfusion. Although the ID is not known, it is thought to be small. Syphilis is a systemic infection with the following clinical manifestations: (1) primary syphilis is characterized by a chancre at the site of infection. The chancre progresses from a small, red, hard bump to an enlarged lesion with a shallow crater surrounded by firm margins. Chancres most commonly occur on the genitalia (and are painless at this site) but may also occur on the lips, nipples, fingers etc. The chancre heals in about 4-6 weeks. After a latent period, the disease then progresses to the next stage. (2) Secondary syphilis occurs about 3 weeks to 6 months after the chancre heals. The disease is now systemic and this stage is characterized by fever, headache, sore throat and a peculiar red or brown rash that disappears in a few weeks (in general). (3) After these symptoms disappear, @ 30% of those infected will enter a highly varied latent period (up to more than 20 years). The final or tertiary syphilis is rare due to the use of antibiotics (to treat other infections ). Tertiary syphilis is characterized by a variable combination of: cv problems, gummas (soft granulomas) of the liver, bones, skin, and neurosyphilis giving rise to severe headaches, convulsions, derangement, blindness, and loss of coordination. 3. Dx - serology, dark-field microscopy 4. Tx - antibiotics 5. Prevention - safe sex, and abstinence __________________________________________________________________________________________________________ Lancaster Bio 240 Revised Winter 2006 10 D. Chancroid is another STD (Table 26.12 figure 26.17). It is caused by Haemophilus ducreyi. The manifestation is a single or multiple genital sore(s) that are painful (unlike the chancre of syphilis: see figure 20.16). It is more common in other countries than in the U.S. (about 800 cases/yr in U.S.). Dx involves the identification of the organism from the lesions or fluid from the lesions. Although it is often self-limiting, antibiotics can be used for treatment. E. Genital Herpes. Table 26.13 and figure 26.18 1. Cause - herpes simplex virus usually type 2 2. This is among the top four most common STIs and rarely non-sexual transmission occurs. Symptoms include itching, burning, and in women sometimes pain. Then vesicles occur and ulcerate. Like oral herpes infections, these become latent and then reoccur. A complication is a congenital infection that can be fatal or cause brain damage and that is acquired from mom which can be prevented in most cases by a C-section. In addition, the risks of cervical cancer increases in women with herpes. 3. Dx - tissue culture 4. Tx - of symptoms with medication such as acycclovir that decreases the severity of the disease and the incidence of recurrences. 5. Prevention – monogamy, safe sex helps but condoms do not eliminate the chance of transmission, and abstinence F. Genital Warts. Table 26.14 and Figure 26.19 1. Cause - papillomaviruses 2. Genital warts are one of the most common STIs in the US (at least ½ of sexually active men and women become infected at some point during their lifetime) The warts are unsightly or they mayasymptomatic or silent. The silent types have been linked to an increased risk of cancer (cervical and penile). However, the warts do not always develop but the person is still infected. Infected mothers occasionally transmit these warts to their babies that cause infections of the respiratory tract. 3. Dx – symptoms, a new screening test that replaces the original pap smear, DNA tests can determine if someone is infected with a strain linked to cancer. 4. Tx - wart removal 5. Prevention - safe sex and abstinence, although condoms do not work as well in preventing the transmission of these viruses G. Acquired Immunodeficiency Disease (AIDS) Table 26.15 1. Cause - Human Immunodeficiency Virus 2. AIDS is one of the biggest concerns worldwide due to the high mortality associated with it. It is among the leading causes of death in young adults. It cripples the immune system and thus infections occur that are eventually fatal. It is estimated that 1 to 2 million Americans are infected with HIV and perhaps as many as 9 million. World-wide it is estimated that 4.8 became infected in 2003. In that same year, 2.9 million died. 3. Dx - serology 4. Tx - new drugs prolong life but so far there is no cure 5. Prevention - safe sex and abstinence, universal blood and body fluid precautions, and screening blood and tissue donors. _________________________________________________________________________________________________________ Lancaster Bio 240 Revised Winter 2006 11 H. Vulvovaginal candidiasis Table 26.4 1. Cause - Candida albicans 2. This infection is characterized by itching and sometimes a rash on the external genitalia of women. However, it is sometimes asymptomatic. Antibiotic therapy, pregnancy, diabetes and the use of oral contraceptives are predisposing factors. 3. Dx - the presence of budding yeast in a vaginal smear 4. Tx - Antifungal medications 5. Prevention I. Trichomoniasis or Trich Table 26.16 and Figure 26.22 1. Cause - Trichomonas vaginalis 2. This infection is not always symptomatic but when it is symptoms are most likely to occur in women (burning, itching, and a yellowish discharge). Humans are the only reservoirs but the parasite can survive for short periods of time in other moist environments and thus is occasionally transmitted nonsexually. 3. Dx - presence of the parasite in vaginal smear 4. Tx - antiparasitic drugs 5. Prevention - safe sex and abstinence J. Toxic Shock Syndrome 1. Cause - Staphylococcus aureus 2. The symptoms of TSS include fever, diarrhea, muscle aches, and a rash. It is caused by the production of toxins and is exacerbated by the use of highly absorbent tampons (or tampons that are left in for long periods of time) that result in a decrease in the amount of Magnesium in the vagina. See figure 26.6 3. Dx - culture and isolation 4. Tx - antibiotics 5. Prevention - frequent changing of tampons K. Puerperal sepsis 1. Cause - Streptococcus pyogenes and sometimes other bacteria 2. Although puerperal sepsis (AKA childbed fever) is now rare due to aseptic practices during childbirth, occasionally outbreaks do occur. In the past, this disease resulted in a relatively high mortality in post partum women 3. Dx - culture and isolation, serology 4. Tx - antibiotics 5. Prevention - aseptic conditions during childbirth _________________________________________________________________________________________________________ Lancaster Bio 240 Revised Winter 2006 12 L. Bacterial vaginitis table 26.3 is characterized by a grayish-white, slightly bubbly discharge from the vagina, an odor, decrease in the pH of vaginal secretions, and the presence of clue cells (figure 26.4). The cause is unknown, but the bacterium, Gardnerella vaginalis is present. M. Multicellular parasites (e.g.,lice AKA crabs, scabies, caused by mites) are also common. Infections of the Central Nervous System (Chapter 27) I. The CNS is normally devoid of microbes Figure 27.1 II. Infections of the Nervous System (sources include: blood, skull bones, or nerves) A. Meningitis (bacterial). Table 27.1 for meningococcal meningitis. Figure 27.5 Note that meningitis can also be of viral origin 1. Cause - there are several species of bacteria that cause meningitis including Escherichia coli, other Enterobacteriaceae and streptococci (leading causes in newborns), Streptococcus pneumoniae, and Staphylococcus (leading causes in adults), Hemophilus influenzae, and Neisseria meningitidis (leading causes in preschool age children), and N. meningitidis and S. pneumoniae (leading causes in youth and young adults. The mortality of meningococcal meningitis is 1% with the best treatment, but 15% with delayed treatment and 85% with no treatment. Death can occur in 12-18 hours if treatment is delayed. The mortality rate for pneumococcal meningitis is 40%. Another bacterium that sometimes causes outbreaks of meningitis is Listeria monocytogenes (normally asymptomatic or with subclinical symptoms, but can also cause miscarriage or premature deliveries). 2. Most cases of meningitis occur in children under five. This disease is very serious and can be rapidly fatal (esp. meningococcal meningitis). Symptoms include severe headache, fever, and intense pain of the neck and back. A petechial rash can occur with meningococcal meningitis. 3. Dx - culture and isolation and Gram Stains of CSF 4. Tx – antibiotics without delay 5. Prevention - there are vaccines for some of the bacteria or some strains of some species. For meningococcal meningitis, prophylactic antibiotics are administered to contacts. B. Listeriosis (Table 27.2) a. Cause Listereria monocytogenes b. Symptoms- flu-like with or without gastrointestinal involvement, meningitis In pregnant women it causes miscarriage. c. diagnosisd. Treatment- antibiotics ASAP e. Prevention. Involves proper food handling and pasteurization. ___________________________________________________________________________________________________ Lancaster Bio 240 Revised Winter 2006 13 C. Leprosy (Hansen’s disease) Table 27.3 figure 27.9 1. Cause - Mycobacterium leprae 2. Leprosy is a common (but less common than before, with less than 2.5 million active cases worldwide) disease. Humans and armadillos are the reservoirs. Health and living conditions are predisposing factors. After exposure, the macrophages of most people destroy the bacteria. If not, the incubation is commonly 2-5 years, but can be as long as 20 years. The possible forms of the disease include : (1) tuberculoid leprosy which is the most superficial form with shallow painless solitary lesions, and (2) lepromatous leprosy is characterized by the formation of disfiguring lepromas. 3. Dx - Acid fast stain, and feather test for loss of sensitivity. 4. Tx - antibiotics 5. Prevention - sanitary living conditions, handwashing, but no vaccine D. Botulism Table 27.4 1. Cause - toxins of Clostridium botulinum 2. Botulism is an intoxication associated with eating poorly preserved foods (or more rarely: by colonization of the human intestine or wound infections). The spores gain access to the food products which are inadequately cooked in a pressure cooker that does not reach sufficient pressure and temperature, canned (and thus anaerobic conditions exist for germination and growth), and then contamination with the toxin botulin (the most powerful toxin known to man). Symptoms appear 12-36 hours after eating the toxin that prevents neural impulse transmission. Nausea and vomiting may not occur but the muscles of the head are affected first resulting in double vision, and difficulty in swallowing and speaking. Later symptoms involved descending paralysis. The fatality rate has dropped due to the use of technology (e.g., respirators) but is still about 25%. 3. Dx - identification of toxin 4. Tx - antitoxin 5. Prevention - proper canning techniques and adequate heating of food before eating. E. Viral Meningitis and Encephalitis Tables 27.5 and 27.6 1. Cause - various viruses can cause meningitis and encephalitis, some cases are sporadic that result from viruses that cause other diseases (e.g., mononucleosis), and some are arthropod borne and spread by the bites of insects. Some viruses cause epidemics of these diseases. 2. Symptoms include: fever, headache, stiff neck, disorientation, and seizures and coma. Although some people die, most recover but some are left with disabilities. 3. Dx - rule out bacterial encephalitis 4. Tx - symptoms 5. Prevention - for the arthropod borne forms avoiding biting insects (especially mosquitoes) and use repellents ___________________________________________________________________________________________________________ Lancaster Bio 240 Revised Winter 2006 14 F. Poliomyelitis Table 27.7 Figures 27.15-27.17 1. Cause – three types of poliovirus 2.The first symptoms mimic meningitis followed by pain and spasms of some muscles and later, paralysis. The virus enters the mouth and infects the throat and intestine then the blood. This disease is interesting in that areas with poor sanitation, babies develop immunity and thus do not suffer the severe sequel (paralysis), but in areas with good sanitation, natural immunity does not exist and many children can suffer paralysis. Post polio syndrome can occur 10-50 years after infection and which can result in severe disability. 3.Dx – cultures from throat and feces 4.Tx – treat symptoms 5.Prevention- vaccination. G. Rabies Table 27.8 figures 27.18-27.19 1. Cause - a rhabdovirus 2. Rabies is not common in humans but when it does occur it is often fatal (only two people have been known to survive and recover0 after the symptoms appear (50% die within 4 days after symptoms appear and others soon afterwards). It results from a bite by an infected non-human animal (remember Cujo). Symptoms begin (after a long incubation time up to six years) with a fever, sore throat, headache, muscle aches, fatigue, and nausea then progress to an encephalitis, agitation, confusion, hallucinations, seizures, and sensitivity to light, touch, and sound. Then a high fever and frothing at the mouth occur. There are 0-4 human cases of rabies in the US each year and about 5,000 wild animal cases each year. 3. Dx - fluorescent antibody staining of smears from conjunctiva, fatty tissue of the neck or tissue from the brain. 4. Tx - After symptoms begin - none, vaccination as soon as possible after exposure 5. Prevention - the vaccination of domestic animals and avoiding suspicious animals H. Cryptococcal meningoencephalitis Table 27.9 1. Cause - Cryptococcus neoformans 2. This fungus primarily gains access via the respiratory system. In healthy individuals it cause a subclinical an rapidly resolved respiratory infection or develop into a serious disease but very slowly. In the immunocompromised the fungus can spread to the CNS with a significant mortality rate. 3. Dx - India ink preparation (a wet mount, see figure 27.20) and culture 4. Tx - antifungal medications 5. Prevention – none really except avoidance of bird droppings ________________________________________________________________________________________________________ Lancaster Bio 240 Revised Winter 2006 15 I. African Sleeping Sickness Table 27.10 1. Cause - Trypanosoma brucei (figure 27.21) 2. The vector is the tsetse fly. After a bite, a nodule appears at the site, then lymph nodes may enlarge. After this the symptoms may disappear. Weeks to years later, cyclic fevers occur. AS the CNS becomes involved, apathy, decreased activity, slurred speech, coma and eventually death occur. There are about 10,000-20,000 new cases each year. 3. Dx - presence of the parasite in stained blood, tests for antibodies. 4. Tx - antiparasitic drugs, but the more advanced the lower the TR and the increased serious side effects. 5. Prevention - avoidance of vector J. Ameobic meningoencephalitis 1. Cause - Naegleria fowleri, and Acanthoamoeba 2. These free-living amoebas cause a rare but in most cases, fatal infection. Naegleria gains entry through the nasal passages while a person is swimming. 3. Dx - presence of the parasite in CSF 4. Tx - no effective 5. Prevention - avoid swimming in stagnant waters K Prions are proteinaceous particles that have been implicated in diseases such as bovine spongiform encephalopathology, scrapie, Kuru, and Creutzfeldt-Jakab disease. See Table 27.11 ____________________________________________________________________________________________________________________ Lancaster Bio 240 Revised Winter 2006 16 Biology 240 Final Study Guide. There may be a couple of questions added or deleted in lecture 1. Where is normal flora found in the upper alimentary system? 2. Where are normal flora found in the lower alimentary system (include weight and species)? 3. What is the most common bacterial infection? 4. What is gingivitis? 5. What are the symptoms of oral herpes? 6. What is herpatic whitlow and how is it acquired? 7. What are the symptoms and complications of mumps? 8. How are mumps diagnosed and prevented? 9. Describe in detail the disease caused by Helicobacter pylori? 10. What causes cholera? what are the symptoms and treatment? 11. What are the symptoms and infectivity of Shigellosis? 12. Compare and contrast non-typhoidal fever and typhoid (include details). 13. What are the symptoms, cause, and complications of bacterial gastroenteritis? 14. What are the symptoms of food poisoning? How is it cured? What are the bacteria responsible for it? 15. Describe botulism in detail. 16. Compare the organisms responsible for viral hepatitis. 17. How many cases of viral gastroenteritis occur in the US each year? 18. Describe giardiasis in detail. 19. What are the morbidity and mortality rates of amebic dysentery? What are the complications? 20. Describe the disease caused by Cryptosporidium. 21. Briefly describe the worms that affect the lower alimentary system. 22. List the organisms that can cause bladder infections. 23. Describe gonorrhea in detail. 24. What are the symptoms and diagnosis of Chlamydial infections of the genital tract and the eye? 25. Describe syphilis in detail. Briefly describe chancroid and bacterial vaginosis. 26. What are the symptoms of genital herpes? 27. What are the complications of genital warts, and what is the prevention of this viral infection? 28. Why is AIDS so serious, what is the morbidity and mortality? 29. What are the symptoms and predisposing factors of vulvovaginal candiasis? 30. What causes Toxic Shock Syndrome and what exacerbates it? 31. Why is puerperal sepsis rare today and what is it? 32. Describe bacterial meningitis in detail. 33. Describe leprosy in detail. 34. What are the causes and symptoms of viral encephalitis? 35. What is the cause and symptoms of rabies, prognosis before symptoms? prognosis after symptoms appear? 36. What is the mortality of infections caused by Cryptococcus neoformans, how is it diagnosed. 37. Describe African Sleeping Sickness in detail. 38. What is the mortality rate of ameobic meningoencephalitis? 39. Describe tetanus in detail 40. Define microbe, miroorganisms, and microbiology. Why should we care about these organisms? 41. Compare and contrast prokaryotes and eukaryotes. 42. Describe in detail the Gram stain and know what color Gram - and Gram + are at each stage. 43. Define aerobe, anaerobe, microaerophile, facultative anaerobe, obligate aerobe, obligate anaerobe and discuss the impact these oxygen requirements have on culturing these organisms. 44. Be able to draw and label a typical growth curve of bacteria confined to a culture medium. 45. What are the components of nucleic acids and what are the five bases? 46. Define recombination, transformation, conjugation, and transduction. 47. What are the factors that affect the relationships between disease causing microbes and humans. 48. What are the components of the First, Second and Third Lines of Defense against disease? 49. Discuss cell-mediated and humoral immunity. 50. Know the general methods that are used to control microbes (do not worry about the specifics; e.g. the types of chemical agents). 51. Review antibiotic resistance. 60. Discuss the relative impacts of the top nine scourges in industrial versus third-world countries. Are citizens of the US really safe? Lancaster Bio 240 Revised Winter 2006 17 61. Know the organisms that are responsible for, the symptoms and prognosis the following: SSSS, Rocky Mountain Spotted Fever, Lyme Disease, Chicken pox, Rubella, Otitis media, Common Cold, Influenza, Bacterial Pneumonia, septicemia, acute and subacute bacterial endocarditis, malaria, plague, and Tuberculosis.