Microbiology Lecture Test 4

defenses of the GI tract

mucus, IgA antibodies, peristalsis (muscle contractions), lysozyme & lactoferrin in saliva, acidity of stomach fluid, antimicrobial properties of bile, gut associated lymphoid tissue

functions of the normal microbiota in the GI tract

aids in digestion, provides essential nutrients, trains immune system, protects against pathogens

acute diarrhea

defined as 3+ loose stools in a 24h period, often accompanied by fever, abdominal pain, cramping, nausea, vomiting, and dehydration; most often transmitted by contaminated food

Salmonella enterica

gram-negative bacilli with flagella, glucose fermenting; causes salmonellosis characterized by vomiting, diarrhea, mucosal irritation, and bloody stool, or more rarely, typhoid fever characterized by high fever, headache, muscle aches, stomach pain, diarrhea, and rash; commonly found in raw meat, dairy, eggs, and animals such as reptiles; treated with fluid/electrolyte replacement, antibiotics in severe cases

Shigella

group of gram-negative bacilli that are nonmotile, non-sporulating, and do not produce urease or H2S; infection characterized by bloody diarrhea, fever, intense abdominal pain, nausea, and vomiting; produces endotoxin, enterotoxin, and shiga toxin, enters mucosa of the colon and initiates inflammation; reservoirs are humans and primates, transmitted via fecal-oral route; no treatment required unless patient is immunocompromised

shiga-toxin-producing E. coli (STEC)

most virulent strain of Escherichia coli (gram-negative bacilli) that produces shiga toxin; infection characterized by gastroenteritis, fever, bloody diarrhea, and rarely hemolytic uremic syndrome or neurological symptoms; transmitted via fecal-oral route, usually through food; treated only with supportive therapy and plasma transfusions

Campylobacter jejuni

curved/spiral gram-negative bacteria with flagella; most common cause of diarrhea in the U.S., infection characterized by weeks of diarrhea, fever, vomiting, headaches, and severe abdominal pain; reservoirs include animals, humans, food, and beverages, and is transmitted via fecal-oral route, usually through food; treated with rehydration/electrolyte therapy and antibiotics if necessary, though antibiotic resistance is growing due to poultry industry

Clostridioides difficile

gram-positive bacilli, sporulating; causes pseudomembranous colitis aka antibiotic-associated colitis, characterized by diarrhea following antibiotic therapy, and in severe cases, abdominal cramps, fever, leukocytosis, inflamed colon, and cecum perforation; treated with antibiotic withdrawal, fluid/electrolyte replacement, narrow-spectrum antibiotics, fecal transplants, and isolation

Vibrio cholerae

gram-negative curved rods with flagella that produces cholera toxin; infection characterized by vomiting, “rice water stools”, severe dehydration, weight loss, vitamin depletion, acidosis; transmitted via fecal-oral route, most often via water and food, especially in warm, alkaline, and saline environments; vaccine available, treated with oral rehydration therapy and antibiotics

rotavirus

non-enveloped RNA virus that is the most common cause of death resulting from diarrhea, particularly affecting infants; infection characterized by diarrhea, fever, vomiting, dehydration, shock, intestinal damage, and compromised nutrition; transmitted via fecal-oral route; vaccine available, treated with fluid/electrolyte replacement

norovirus

naked RNA virus that is a common cause of hospitalization due to foodborne illness; infection characterized by diarrhea, vomiting, and fever; transmitted via fecal-oral route, often through food or water; treated with fluid/electrolyte replacement

Staphylococcus aureus exotoxin

gram-positive cocci that can cause food poisoning; commonly transmitted in contaminated foods, especially custards, sauces, and processed meats (does not change the appearance, scent, or taste of the food), though it is not contagious; ingestion of toxin acts on gastrointestinal epithelium, causing cramping, nausea, vomiting, and diarrhea

Bacillus cereus exotoxin

gram-positive, sporulating bacteria that can cause food poisoning; reservoir is soil, toxin is commonly transmitted through contaminated food, but is not contagious; emetic form primarily causes vomiting and is associated with fried rice and pasta that has been kept warm; diarrheal form primarily causes diarrhea and is associated with cooked meats or vegetables that have been kept warm

Clostridium perfringens exotoxin

gram-positive, sporulating bacteria that can cause food poisoning; toxin is commonly found in meat and vegetables that have been left out or eaten without reheating; toxin acts on epithelial cells causing abdominal pain, diarrhea, and nausea

Giardia duodenalis

symmetrical, heart shaped protozoa with 4 flagella, can cause chronic diarrhea; infection characterized by diarrhea of long duration, abdominal pain, flatulence, and greasy/foul smelling stools; reservoir is commonly freshwater, but humans and animals are also carriers, and cysts often play a role in transmission; treated with antibiotics

Streptococcus mutans

gram-positive cocci that cause dental caries/tooth decay; infection characterized by disruption in the tooth enamel that can progress into the deeper layers of the tooth, causing toothaches; transmitted via oral-oral contact; can produce glucose polymers in the presence of sucrose, helping them bind to the enamel; can only be treated by removal of the infection and tooth restoration

periodontitis

oral infection caused by a polymicrobial biofilm; gingivitis (first stage) characterized by swelling, redness, and bleeding of the gums, if not treated, gingivitis turns to periodontitis, characterized by more severe gum recession and can lead to tooth loss; treated with removal of calculus and plaque, surgery, and antibiotics

Helicobacter pylori

gram-negative comma-shaped bacteria that causes gastritis and gastric ulcers; gastritis characterized by sharp or burning pain in the abdomen due to inflammation of the stomach lining, while gastric ulcers are lesions of the mucosa of the stomach or duodenum that can be accompanied by bloody stools and vomiting, often worsening after eating or when under stress; bored through mucosa of stomach and produces urease to persist in the high acidity; transmitted via oral-oral or fecal-oral route; treated with antibiotics and can be prevented with acid suppressors

hepatitis (general)

viruses that cause inflammatory disease marked by necrosis of liver cells and sometimes jaundice; can also be noninfectious, causes by autoimmune diseases or drug/alcohol abuse

hepatitis A & E

ssRNA nonenveloped viruses that cause minor, self-limited hepatitis, though can be life threatening for pregnant people & immunocompromised; infection characterized by mild flulike symptoms, possibly jaundice and swollen liver; transmitted via fecal-oral route, often from food, sexual intercourse, or travel; vaccine available for Hep A, no specific treatments for A or E

hepatitis B and D

enveloped viruses, though Hep D can only propagate in the presence of Hep B; infection causes direct damage to liver cells causing fever, chills, malaise, anorexia, abdominal discomfort, diarrhea, nausea, and sometimes glomerulonephritis and arterial inflammation, though most patients livers heal completely; transmitted through blood, sexual intercourse, or from mother to child; vaccine available, and immediate protection can be given with hepatitis B immune globulin; mild cases can be treated with supportive care, and chronic infections can be controlled with recombinant human interferons and antiviral drugs

hepatitis c

RNA virus that causes the “silent epidemic”; infection is often asymptomatic but can cause chronic liver disease and liver cancer; transmitted through blood; no vaccine available, but there are tailored treatments that can be curative

Enterobius vermicularis

aka the pinworm or seatworm, a common helminth especially in children; transmitted by the ingestion of eggs through contaminated food, drink, or on hands; infection characterized by anal itching, disrupted sleep, nausea, abdominal discomfort, and diarrhea; tested with tape over the anus and can be treated with antihelmintics

Taenia solium

aka the pork tapeworm that causes cysticercosis; eggs hatch in the small intestine of the pig, larvae migrate and encyst in the muscles which are ingested by humans, in which the cysteri are digested into the intestines where they attach and mature

Schistosoma

group of blood flukes that cause schistosomiasis; infection characterized by inflammation and swelling of the spleen, bladder, and liver; defacation or urination in bodies of water releases eggs, which intermediately infect snails until they become cercaria which can burrow through the skin when exposed to the water

defenses of the urinary tract

urine flushes the tract, acidic pH of urine, lysozyme & lactoferrin in urine, IgA antibodies

defenses of vagina

mucus lining, IgA antibodies, low pH

urinary tract infection (cystitis)

usually caused by normal biota of the GI tract, especially E. coli; characterized by frequent urge to urination, painful urination, cloudy or bloody urine, fever, and nausea; can spread to kidneys causing pyelonephritis which is characterized by back/flank pain and fever; not transmitted from person to person; treated with antibiotics and pain medication

gonorrhea

reproductive disease caused by Neisseria gonorrhoeae, a gram-negative, kidney bean shaped diplococci; characterized by urethritis, painful urination, and yellow discharge in men, and pus/bloody vaginal discharge and possible painful urination in women, can also lead to pelvic inflammatory disease and infertility; transmitted through sexual intercourse or from mother to baby, prevented by condoms; treated with 2 types of antibiotics simultaneously

chlamydia

reproductive disease caused by Chlamydia trachomatis, a gram-negative bacteria; often asymptomatic, but males may experience discharge and painful urination, possibly leading to epididymitis, and females may experience cervicitis, discharge, inflammation of fallopian tubes, and pelvic inflammatory disease; can cause eye infections and pneumonia in babies born to infected mothers; transmitted through sexual intercourse or from mother to baby, prevented by condoms; treated with antibiotics

Candida albicans

normal fungus of the microbiota that can cause vaginitis; infection characterized by vaginal inflammation, itching, burning, and chunky discharge; can be transmitted sexually, though is usually an opportunistic infection; treated with antifungals

Gardnerella

group of gram-variable coccobacilli that causes vaginosis aka BV; infection characterized by vaginal discharge with a fishy odor, itching, and burning and can lead to pelvic inflammatory disorder, infertinity, and ectopic pregnancies; cause is unknown; diagnosed by “clue cells” in a vaginal sample; treated with antibiotics

Trichomonas vaginalis

pear-shaped protozoa with 4 flagellas and an undulating membrane, cause of vaginitis aka trichomoniasis; often asymptomatic, but causes white/green frothy vaginal discharge in women and can lead to infertility and susceptibility to infections; transmitted through sexual intercourse; treated with antibiotics

Treponema pallidum

gram-negative spirochete that causes syphilis; primary stage characterized by a hard, papule at the site of entry (chancre) that heals within weeks; secondary stage characterized by fever, headache, sore throat, lymphadenopathy, and red/brown rash; latent/tertiary stage characterized by cardiovascular damage, neurology symptoms, and gummas (painful, swollen nodules); transmitted through sexual intercourse, prevented by condoms; treated with antibiotics

genital herpes

caused by HSV-1 and HSV-2, a small, enveloped virus; characterized by small, painful vesicles with clear fluid on genitalia, perineum, thigh, and/or buttocks, sometimes accompanied by malaise, anorexia, fever, and swelling and/or tenderness of the groin; latent infection can reoccur, often triggered by stress, UV radiation, injury, or menstruation; transmitted through sexual intercourse or other direct contact, even when no lesions are present; prevented by avoiding contact or using condoms, treated with antivirals, though there is no cure

human papillomavirus

group of nonenveloped DNA viruses that cause HPV infection; infection characterized by small warts on/around the genitals or anus, and condyloma acuminata (cauliflower-like masses), can lead to various cancers; transmitted through direct contact; vaccine can prevent some strains, the only treatment is wart removal

defenses of the respiratory tract

nasal hairs, mucous, cilia, complement proteins, antimicrobial peptides, macrophages, IgA antibodies

pharyngitis

respiratory disease caused by a variety of bacteria (ex: S. pyogenes, Fusobacterium necrophorum) or viruses (ex: common cold); infection characterized by inflammation of the throat, swollen tonsils, foul-smelling breath, headache, and white patches in the throat (bacterial infection can also cause fever, headache, nausea); can progress to scarlet or rheumatic fevers (if pyogenes) or lemierre’s syndrome (if necrophorum); transmitted through respiratory droplets or direct contact with mucus; treated with antibiotics if bacterial

common cold

respiratory disease caused by a variety of viruses such as rhinovirus, coronavirus, and adenovirus; infection characterized by sneezing, scratchy throat, runny nose, and fever; transmitted by respiratory droplets; treated with symptom alleviation

sinusitis (aka sinus infection)

respiratory disease caused by various viruses or bacteria, often mixed, sometimes caused by fungi in immunocompromised patients; infection characterized by sinus pressure/pain, congestion, and thick mucus; does not spread from person to person, often progresses from the common cold or flu; if unresolved after multiple weeks, can be treated with broad-spectrum antibiotics

acute otis media (aka ear infection)

bacterial or viral infection of the middle ear, most often caused by Streptococcus pneumoniae or Candida auris; caused by migration of microbes from the upper respiratory tract; vaccine available, can be treated with antibiotics if infection persists and/or tympanic membrane tubes if infections are chronic

Streptococcus pneumoniae pneumonia

lethal respiratory disease caused by small gram-positive flattened cocci; favorable conditions for infection include old age, winter, underlying respiratory disease, diabetes, chronic alcohol or narcotic use; can be prevented by PCV15 or PVC20 vaccines

Legionella pneumophila pneumonia

respiratory disease caused by gram-negative bacteria ranging from cocci to filaments; commonly contracted from tap water or other fresh water sources

atypical pneumonias

subacute respiratory disease aka “walking pneumonia” caused by Mycoplasma and Chlamydophila bacterial species; can be treated with antibiotics if necessary

Histoplasma capsulatum pneumonia

respiratory illness caused by fungus that is found in soil in eastern/central U.S.

Pneumocystis (carinii) jiroveci pneumonia

respiratory disease caused by fungus; associated with AIDS patients and likely transmitted through the inhalation of spores

viral pneumonia

common type of community-acquired pneumonia that is generally less severe and caused by viruses of the upper respiratory tract or human metapneumovirus

healthcare-associated pneumonia

lethal respiratory disease with a variety of causes including MRSA, Enterobacter, E. coli, and other gram negative bacteria; often acquired from aspiration during ventilation; prevented by proper healthcare measures, should be treated with antibiotics promptly

influenza

respiratory disease caused by influenza viruses A, B, and C; infection characterized by headache, chills, cough, aches, fever, congestion, sore throat, and extreme fatigue; transmitted by inhalation or respiratory droplets/aerosols or direct/indirect contact, often facilitated by crowding and poor ventilation, prevented by yearly vaccinations; treated with antivirals

antigenic drift

gradual mutation of glycoprotein genes that causes reduced host immune response to a virus, causing seasonal outbreaks of diseases such as influenza

antigenic shift

RNA exchange between viruses, often during coinfection of a host cell, causing pandemics of diseases such as influenza

Bordetella pertussis

gram-negative bacteria that causes pertussis, aka whooping cough; catarrhal stage characterized by runny nose, paroxysmal phase characterized by bouts of severe coughing, convalescent phase is asymptomatic but causes patients to be susceptible to respiratory infections; transmitted through respiratory droplets; vaccine available, treated with antibiotics

respiratory syncytial virus (RSV)

respiratory disease characterized by runny nose, coughing, wheezing, and fever; common in the population, especially during winter and early spring, but infants are at risk for serious illness; transmitted by respiratory droplets or indirect contact, vaccine available for older adults, passive antibody used for high-risk children

Mycobacterium tuberculosis

acid-fast aerobic bacilli that cause tuberculosis; primary infection occurs when tubercles form in the lungs and neutrophils release enzymes causing necrotic lesions that heal by calcification, secondary infection occurs when pathogen is reactivated causing violent coughing, green/bloody sputum, fever, anorexia, weight loss, extreme fatigue, night sweats, and chest pain; transmitted by respiratory droplets, vaccine not administered in the U.S.; treated with strict and lengthy antibiotic regimens

defenses of the cardiovascular system

lymphocytes in blood are responsible for adaptive immunity, phagocytes in blood are responsible for innate immunity

sars-cov-2

enveloped RNA virus with spike proteins that causes covid-19; infection characterized by pneumonia, vomiting, diarrhea, rashes, heart damage, blood clots, loss of taste/smell, headaches, long term cognitive decline; transmitted by direct and indirect contact with respiratory droplets and aerosols, mRNA vaccines and viral vector vaccine available; paxlovid can be used to treat severe or rebounding symptoms

septicemia/sepsis

circulatory disease caused by various bacteria or more rarely, fungi such as Candida auris; infection characterized by fever, altered mental state, shaking, chills, GI symptoms, increased breathing rate, and low blood pressure; treated with antibiotics

acute endocarditis

inflammation of the endocardium most often caused by Staphylococcus aureus; infection characterized by fever, fatigue, joint pain, edema, weakness, anemia, abnormal heartbeat, janeway lesions (red/purple spots on palms and soles), and osler’s nodes (painful red/purple bumps on fingertips and toes); transmitted by IV drug use or traumatic injuries/surgery; treated with antibiotics and surgery if necessary

subacute endocarditis

mild inflammation of the endocardium caused by bacteria that are often part of the normal biota; infection characterized by fever, fatigue, joint pain, edema, weakness, anemia, abnormal heartbeat, janeway lesions (red/purple spots on palms and soles), osler’s nodes (painful red/purple bumps on fingertips and toes), and spleen enlargement; caused by minor disruptions of skin or mucus membranes that let bacteria into the bloodstream; treated with antibiotics

Bartonella henslae

gram-negative bacillus that causes cat scratch disease; infection characterized by clusers of small papules at the site of inoculation, lymph nodes may become enlarged and painful; transmitted by cat scratches or bites; prevented with flea control and by cleaning wounds caused by cats; treated with antibiotics

Rickettsia rickettsii

gram-negative bacteria that causes spotted fever rickettsioses; infection characterized by fever, chills, headache, muscular pain, spotted rash, cardiovasculat symptoms, convulsions, tremor, and coma; transmitted by tick bites; treated with doxycycline

Plasmodium

group of protozoa that cause malaria; infection characterized by malaise, fatigue, aches, nausea, diarrhea, chills, fever, and sweating; transmitted by mosquitos, prevented with netting, screens, insect repellant, and prophylactic drugs; treated with quinine

HIV