Exam 4 Review: Bacteria PDF
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Elmhurst University
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This document is a review on bacteria, discussing various types and their characteristics. It covers Enterobacteriaceae, Gram-negative rods, and classification methods, including the classification based on features of the cell and the diseases caused. It's likely part of an educational module.
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xam 4 review E Bacteria Enterobacteriaceae ○ Often referred to as the “enterics” → found in the enterics or digestive system ○ Often associated with intestinal infections ○ Part of the normal flora of the intestinal tract of an...
xam 4 review E Bacteria Enterobacteriaceae ○ Often referred to as the “enterics” → found in the enterics or digestive system ○ Often associated with intestinal infections ○ Part of the normal flora of the intestinal tract of animals ○ Can also be found world-wide in most habitats Soils, water, fruit, vegetables, flowering plants, trees, and plant tissues ○ Causative agents of enteric diseases as dysentery, typhoid, and food poisoning ○ Biochemical tests are crucial for the identification, diagnosis, and treatment of infection since they are so similar General characteristics of Enterobacteriaceae ○ Gram negative rods ○ Catalase positive ○ Oxidase negative In the intestinal tract Oxidase positive in the lab ○ Most are actively motile 2 are non-motile ○ Ferment glucose and produce acid end products ○ Reduce nitrate → nitrite ○ Not nutritionally fastidious Two ways of classification ○ 1. Serological classification(features of the cell): look at ability to colonize, adhere(attach), produce toxins, and invade tissues; some possess plasmids Antigens that help us to identify O antigen: heat stable; somatic antigen H antigen: flagellar antigen; heat-labile K antigen: capsular antigen; heat-labile; some will produce capsules ○ 2. Disease that they cause: divided into two categories Primary(frank) pathogen: cause a variety of diarrheal disease in humans and animals; major cause of death among young children Genera:Salmonella, Shigella, Yersinia, and Escherichia Opportunistic pathogens: not normally associated with diarrheal disease unless they get into new environment; may produce serious extraintestinal opportunistic infections outside their habitat Genera:Citrobacter, Proteus, Klebsiella, Enterobacter, Edwardsiella, Providencia, some Escherichia Terms: ○ Diarrhea: frequent, liquid(watery) stools ○ D ysentery: a disease marked initially by frequent watery stools but followed by scant stool production characterized by excretion of mucus, blood. Usually pain and fever ○ Enteritis: inflammation of the intestine ○ Gastroenteritis: inflammation of the entire digestive tract ○ Enteric fever: acute illness initially presenting as fever, headache, abdominal pain, cramping, occasional skin rash, and bacteremia ○ Food poisoning: the ingestion of food or drink that contains a preformed toxin. No growth of bacteria in the host is required ○ Emesis: vomiting ○ Malnutrition: poor nutrition ○ Undernourished: don’t have sufficient calories to support normal body function ○ Infant mortality: death in children up to the age of one ○ Childhood mortality: death in children up through the age of 12 Escherichia ○ Most significant species in the genus is Escherichia coli Both an opportunistic and primary pathogen, depending on the strain Normal flora of the human intestinal tract Produce vitamin K in the large intestine ○ Enteroaggregative Escherichia coli (EAggEC) Opportunistic pathogen Normal intestinal flora strain of E.coli in humans Most likely will not cause disease If it does cause diarrheal disease, it would cause it byattachingto the mucosal surface of the intestine Symptoms: watery diarrhea, vomiting, dehydration, and occasionally abdominal pain Can produce K antigen Common cause of urinary tract and kidney infections in humans Cells attach to epithelial cells lining the urinary tract (adhesin proteins) Virulence factors: ○ Capability of the organism to adhere to the epithelial cells ○ Able to produce hemolysins Common cause of septicemia and meningitis among neonates Acquires infection in the birth canal before or during delivery Can cause meningitis in adults (rare) Can cause bacteremia in adults ○ Enteropathogenic Escherichia coli (EPEC) Common cause of childhood diarrhea Opportunistic pathogen Attachesto cells ofsmall intestine (target) Destroy microvilli without actual invasion Symptoms: Low grade fever Malaise Vomiting Diarrhea (water and non-bloody) ○ Enterotoxigenic Escherichia coli (ETEC) Opportunistic pathogen Common cause of traveler’s diarrhea Infectious dose: 1 million to 10 billion cells Target:small intestine Toxins Heat-labile toxin Heat-stable toxin Symptoms: Non-bloody, watery diarrhea Nausea Abdominal cramps and pain Low grade or no fever No invasion of mucus production Enteroinvasive Escherichia coli (EIEC) ○ Opportunistic pathogen Causes dysentery and symptoms of a disease caused by shigella Infectious dose: 1 million to 100 million cells Capable of direct penetration, cellularinvasion,and local destruction of large intestine mucosa Ability to invade (virulence factor) Symptoms: Fever Severe abdominal cramps Malaise Watery diarrhea Toxemia Following the diarrhea, a period of scant stool containing pus, mucus, and blood will follow ○ Does NOT cause bloody diarrhea Blood comes AFTER ○ Enterohemorrhagic Escherichia coli (EHEC) Frank pathogen No normal flora Strain 0157:H7 Virulence factors: O,H, and K antigens Antibiotic resistant Pili with specific adherence to help itattachto host cells 2 cytotoxins that helpinvadethe host cell Target host cell:colon Cytotoxins cause inflammation of the colon Causes hemorrhagic colitis Blood diarrhea progression to hemorrhagic diarrhea ○ Cytotoxins initiate an overactive immune response Damage to colon is the immune response trying to get rid of the microbe which ends up destroying the cells of the colon Symptoms: Low grade fever Severe abdominal cramps Causes hemolytic uremic syndrome Complication in children Characterized by: ○ Hemolytic anemia ○ Low platelet count ○ Kidney failure or impairment Toxins Verotoxin I and Verotoxin II Able to damage kidney cell lines Verotoxin I can be treated with shigella antitoxin Verotoxin II cannot be neutralized Shigella ○ Frank pathogen and invasive pathogen No normal flora ○ Primary suspect in outbreaks of diarrhea Infectious dose: fewer than 200 cells ○ Humans are only known reservoir ○ Shigellosis Also known as bacillary dysentery Cause of shigella Cause bacteremia If not treated or undertreated Immunosufficent or worse Characterized by: Presence of blood,pus and mucus in stools Abdominal pain and cramps Target host cell:large intestines Shigella attach to specific host cell via invasins Invade and penetrate epithelial cells Another way of host cell death is by the production of shiga toxins Invadeandattach Toxins Shiga toxins (cytotoxin/enterotoxin that destroy epithelial cells lining the lumen of the large intestine) Symptoms: Fever Abdominal pain Diarrhea (often bloody) Salmonella ○ Frank pathogens ○ Transmission is fecal-oral route ○ Normal flora of birds and many reptiles ○ Virulence factors: Vi antigen O antigen K antigen ○ Three types of infection 1. Salmonellosis (gastroenteritis) Exposure is frequent High infectious dose (1 million to 100 millions cells) U.S. source often contaminated poultry and eggs ○ Salmonella typhimurium ○ Salmonella enteritidis Target host cell: small intestine and large intestine Invade intestinal epithelium Incubation period: 12 to 48 hours Symptoms: ○ Low-grade fever ○ Abdominal pain ○ Diarrhea (non-bloody) ○ Vomiting Self-limiting (2 to 5 days) 2. Septicemia Enteric fever: similar to but milder than typhoid fever Caused by Salmonella paratyphi Found in animals 3. Typhoid fever C aused by Salmonella typhi Carried only by humans Caused by the ingestion of food or water contaminated with salmonella typhi Target host cell: small intestine Invades the lymphoid tissue and bloodstream Incubation period: 1-2 weeks Symptoms: ○ High fever ○ Headache ○ Myalgia ○ Gastrointestinal distress (vomiting and diarrhea) ○ Rose spots (some patients) Indicates bacteria is in bloodstream Yersinia ○ Frank pathogens No normal flora ○ No species are known to be normal flora of humans ○ Yersinia enterocolitica Symptoms: Fever Pain of lower right quadrant Cramps Cause of diarrhea in a number of community outbreaks Does not respond to antibiotics ○ Yersinia pestis Causes bubonic and pneumonic plague Carried by rodents and transmitted to humans by fleas Three forms 1. Cutaneous: skin break that does not heal/close properly ○ Allow the microbe into bloodstream ○ Replicate in lymphoids Bubonic Pneumonic: highly contagious and often fatal Insect vector: flea Lower level organism compared to humans that directly transmits a pathogen (usually through a bite) Buboes: grossly swollen lymph nodes Citrobacter ○ Opportunistic pathogen ○ Normal flora of intestinal tract (normal intestinal flora) N ○ ot considered to be an enteric pathogen ○ Citrobacter freundii Most of us carry as normal flora Typically identified in healthy and diarrheal stool cultures Can cause diarrheal symptoms in immunocompromised or worse Cause extraintestinal infections including UTIs, pneumonias, and intra-abdominal abscesses → can lead to sepsis Material from intestinal tract can enter abdominal cavity Klebsiella ○ Opportunistic pathogen ○ Normal flora of gastrointestinal tract of humans and animals ○ Non-motile ○ Virulence factors: K antigen O antigen Heat-stable enterotoxin Contains plasmids that give it antibiotic resistance ○ Klebsiella pneumoniae - causes nosocomial infections in immunocompromised host Infect wounds Cause bacteremia Cause pneumonia (if severe enough) Cause urinary tract infections in catheterized patients ○ Seen more now due to its resistance to more antibiotics Enterobacter ○ Opportunistic pathogen ○ Normal intestinal flora But can cause extraintestinal infections ○ Cause urinary tract infections ○ Enterobacter aerogenes and Enterobacter cloacae Does not cause diarrhea Associated with UTIs and respiratory tract infections Isolated from wounds, urine, blood, and spinal fluid Causes meningitis (rare) ○ Enterobacter agglomerans Causes bacteremia and septicemia Causes UTIs Serratia ○ Opportunistic pathogens ○ Associated with nosocomial outbreaks ○ Lot of antibiotic resistance ○ Produces prodigiosin in under ideal conditions ○ Serratia marcescens Causes UTIs Causes respiratory tract infections Bacteremia outbreaks Causes septic arthritis Contamination of antiseptic solution used for joint injections Proteus ○ Opportunistic pathogen ○ Causes urinary tract infections and nosocomial infections More in people with chronic health problems ○ Highly motile ○ Proteus mirabilis Causes UTIs Causes wound infections ○ Proteus vulgaris Targets immunosuppressed individuals ○ 50% of people have this as normal flora Edwardsiella ○ Opportunistic pathogen ○ Three species in genus ○ Edwardsiella tarda Similar to E.coli; produces hydrogen sulfide ○ Usually found in aquatic animals and reptiles in digestive tract Not know to be normal flora of humans but can cause human disease ○ Causes gastroenteritis ○ Cause wound infections ○ Cause bacteremia (very rare) ○ Pathogen of fish Not human pathogen Providencia ○ Opportunistic pathogens ○ Four genus in species ○ Not common to cause human infection Can cause urinary tract infections in hospital settings Infection in immunocompromised patients are hard to treat because of antimicrobial resistance ○ Providencia alcalifaciens Associated with some cases of diarrhea in children ○ No human normal flora Normal flora of other animals Vibrio G ○ ram negative, curved rod ○ Most of the are found in aquatic or marine environments – typically have requirements for large amounts of water ○ Vibrio fischerii Not human pathogen Form symbiotic, mutualistic relationship with bobtail squid ○ Vibrio cholerae Frank pathogen Causes cholera – acute diarrheal disease (rice water stool) Linked to unsafe drinking water or lack of sanitation Produces toxins AB toxins → causes dehydration (heart muscle, blood, muscles) ○ Moves into bloodstream ○ A → disrupts chloride ion balances ○ B → opens channel in cell membrane People die due to dehydration of entire body Treatment: cholera antitoxin → kills exotoxins Campylobacter spp. ○ Live in the intestine of a number of domestic animals ○ Sources can be unpasteurized dairy products (cheese, milk,etc) ○ Campylobacter jejuni Opportunistic pathogen Not identified until 1980s Gram negative, curved rod Transmitted by fecal-oral route Unique because you do not have to ingest many cells Fewer than 500 cells Diarrheal disease Symptoms: Mild abdominal pain Cramps Diarrhea Self-limiting Lasts 2-6 days People who don’t get treated can become carriers Invasive and attach Small and large intestine Helicobacter spp. ○ Helicobacter pylori Opportunistic pathogen Spiral shape cell C orkscrew motion Causes gastric and duodenal ulcers ○ Difficult to heal Discovered in the 1980s Bacterial infection Treated with antibiotics Sources: unpasteurized dairy products
