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chapter 11

Terms in this set (81)

bartonella
best known as bartonella henselae
gram negative
bacillus
cat scratch disease
brucella
- small
- nonmotile
- coccobacilli
- gram negative
- all species are obligate parasites of mammals
- can cause the disease brucellosis
- can survive phagocytosis - an important element of the bodies defense against bacteria - medical interest
ehrlichia
- gram negative
- rickettsia-like bacteria
- live obligately within white blood cells
- species are transmitted by ticks to humans and cause ehrlichiosis - a sometimes fatal disease
Rickettsia
- obligate intracellular parasite - only reproduce within a mammalian cell
- gram negative
- rod shaped - coccobacilli
- transmitted to humans by bites of insects and ticks
- enter their host cell by inducing phagocytosis - quickly enter the cytoplasm of the cell and begin reproducing by binary fission
- can usually be cultivated artificially in cell culture or chick embryos
- rickettsias are responsible for a number of diseases known as the spotted fever group - these include epidemic typhus caused by Rickettsia prowazeckii, endemic murine typhus caused by R. typhi and Rocky Mountain spotted fever caused by R. rickettsia
- these rickettsial infections damage the permeability of blood capillaries which results in a characteristic spotted rash
Rickettsia - Epidemic typhus
rickettsia prowazekki

transmitted by lice
Rickettsia - Endemic Murine Typhus
R. typhi

transmitted by rat felas
Rickettsia - Rocky Mountain Spotted Fever
R. rickettsii

transmitted by ticks
Neisseria
- aerobic
- gram negative
- cocci - diplococci
- usually inhabit the mucous membranes of mammals
- pathogenic species include the gonococcus bacteria Neisseria gonorrhoeae - the causative agent of gonorrhea - also N. meningitides - the agent of meningococcal meningitis
Bordetella
- nonmotile
- aerobic
- bacilli
- gram negative
- Bordetella pertussis - serious pathogen that causes pertussis, or whooping cough
Burkholderia
- the genus Burkholderia was formerly grouped with the genus Pseudomonas, which is now classified under the gammaproteobacteria
- like the pseudomonads, almost all Burkholderia species are motile by a single polar flagellum or tuft of flagella
- best known species is the aerobic, gram-negative rod Burkholderia cepacia - it has an extraordinary nutritional spectrum and is capable of degrading more than 100 different organic molecules - this capability is often a factor in the contamination of equipment and drugs in hospitals; these bacteria may actually grow in disinfectant solutions; this bacteria is also a problem for persons with the genetic lung disease cystic fibrosis, in whom it metabolizes accumulated respiratory solutions
- Burkholderia pseudomallei - a resident in moist soils and is the cause of a severe disease endemic in southeast Asia and northern Australia
- Nosocomial infections
Pseudomonas - genus within psudomonadales
Opportunistic pathogens
metabolically diverse
oxidase positive
gram negative
bacilli
psudomonadales
gram negative
aerobic rods or cocci
the most important genus in this group are the Pseudomonas
legionella
- oringinally isolated during a search for the cause of an outbreak of pneumonia now known as legionellosis or legionares disease - L. pneumophilia (legionares disease)
- gram negative
- bacilli
- search was difficult because these bacteria did not grow on the usual lab isolation media then available
- special media were developed that enabled researchers to isolate and culture the first legionella
- microbes of the genus known to be common in streams, colonize such habitats as warm-water supply lines in hospitals and water in the cooling towers of air conditioning systems
- an ability to survive and reproduce within aquatic amoebas often makes them difficult to eradicate in water systems
Coxiella
- Coxiella burnetti - causes Q fever - was formerly grouped with the rickettsia
- Require a mammalian host cell to reproduce
- Not transmitted among humans by insect or tick bites
- Most commonly transmitted by aerosols or contaminated milk
- A spore like body in C. burnetii - this might explain the bacterium's relatively high resistance to the stresses of airborne transmission and heat treatment
Vibrionales
- faculatively anaerobic
- gram negative
- rods
- many are slightly curved
- found mostly in aquatic habitats - coastal water
- Vibrio
Vibrio - genus within Vibrionales
- rods that are often slightly curved
- Pathogen - Vibrio cholera - causative agent of cholera - characterized by a profuse and watery diarrhea
- Pathogen - V. parahaemolyticus - causes a less serious form of gastroenteritis - usually inhabiting coastal salt waters, it is transmitted to humans mostly by raw or undercooked shellfish
Vibrio cholera
pathogen within genus vibrio

causative agent of cholera

characterized by a profuse and watery diarrhea
Vibrio parahaemolyticus
pathogen of genus vibrio

causes a less serious form of gastroenteritis - usually inhabiting coastal salt waters, it is transmitted to humans mostly by raw or undercooked shellfish
legionellales
- The genera Legionella and Coxiella are closely associated and were placed in the same order, Legionellales
- Because the Coxiella shre an intracellular lifestyle with the rickettsial bacteria, the ywere previously considered rickettsial in nature and grouped with them
- Legionella bacteria grow readily on suitable aritificial media
enterobacteriales
- Facultatively anaerobic
- Gram negative
- Rods(bacilli) - morphologically the rods are straight
- If motile - petritrichously flagellated - flagella all over the cell
- Important bacterial group called enterics - reflects the fact that they inhabit the intestinal tracts of humans and other animas - most are active fermenters of glucose and other carbs
- Because of the clinical importance of enterics, there are many techniques to isolate and identify them - biochemical tests used - important in clinical lab work and in food and water microbiology
- Enterics have fimbriae that help them adhere to surfaces or mucous membranes
- Specialized sex pili aid in the exchange of genetic info between cells, which often includes antibiotic resistance
- Enterics produce proteins called bacteriocins that cause the lysis of closely related species of bacteria - may help to maintain the ecological balance of various enterics in the intestines
Escherichia
Genus of enterobacteriales

- one of the most common inhabitants of the human intestinal tract and is probably the most familiar organism in microbiology
- E. coli - presence in water or food is an indication of fecal contaminations - not usually pathogenic - however it can be a cause of UTIs and certain strains produce enterotoxins that cause travelers diarrhea and occasionally cause serious foodborne disease
Salmonela
genus of enterobacteriales

- Salmonella - diarrhea
- Gram negative
- Bacilli
- Nonlactose fermenter
- almost all members of this genus are potentially pathogenic
- there are extensive biochemical and serological tests to clinically isolate and identify salmonellae
- common inhabitants of the intestinal tracts of many animals, especially poultry and cattle
- under unsanitary conditions they can contaminate food
- Salmonella enterica - this species is divided into more than 2400 serovars (serological varities) - the term serotype is often used to mean the same thing
- When salmonellae are injected into appropriate animals, their flagella, capsules, and cell walls serve as antigens that cause the animals to form antibodies in their blood that are specific for each of these structures - thus serological means are used to differentiate the microorgansims
shigella
genus of enterobacteriales

- gram negative
- bacilli
- nonlactose fermenter
- responsible for disease called bacillary dysentery, or shigellosis
- found only in humans
- some strains of shigella can cause life threatening dysentery
klebsiella
genus of enterobacteriales

- commonly found in soil or water
- gram negative
- bacilli
- encapsulated
- many isolates are capable of fixing nitrogen from the atmosphere, which as been proposed as being a nutritional advantage In isolated populations with little protein nitrogen in their diet
- Klebsilla pneumonia - occasionally causes a serious form of pneumonia in humans
Serratia
genus of enterobacteriales

- Serratia marcescnes is a bacterial species distinguished by its production of red pigment
- Can be found on catheters, in saline irrigation solutions, and in other supposedly sterile solutions
- Such contamination is probably the cause of many urinary and respiratory tract infections in hospitals
- Gram negative
- Bacilli
- Pink at room temp
proteus
genus of enterobacteriales

- colonies of proteus bacteria growing on agar exhibit a swarming type of growth
- bacilli
- gram negative
- swarmer cells with many flageall move outward on the edges of the colony and then revert to normal cells with only a few flagella and reduced motility - periodically new generations of highly motile swarmer cells develop, and the process is repeated
- very motile
- Proteus colonies have the distinctive appearance of a series of concentric rings
- Implicated in many infections of the urinary tract and in wounds
Yersinia
genus of enterobacteriales

- Yersinia pestis causes plague, the Black Death of medieval Europe
- Gram negative
- Bacilli
- Urban rats in some parts of the world and ground squirrels in the American Southwest carry these bacteria
- Fleas usually transmit the organisms among animals and to humans, although contact with respiratory droplets from infected animals nad people can be involved in transmission
Enterobactor
genus of enterobacteriales

- two Enterobacter species, E. cloacae, and E. aerogenes can cause urinary tract infections and hospital acquired infections
- widely distributed in humans and animals, as well as in water, sewage, and soil
- gram negative
- bacilli
- encapsulated
Erwinia
genus of enterobacteriales

- primarily plant pathogens- some cause plant soft-rot diseases
- these species produce enzymes that hydrolyze the pectin between individual plant cells - thi scauses the plant cells to separate from each other, a disease that plant pathologist term plant rot
pasteruellales
non motile
best known as humans and animal pathogens
pasteurella
- genus of pasteruellales
- gram negative
- bacilli
- primarily known as a pathogen of domestic animals
- causes sepsis in cattle, fowl cholera in chickens and other fowl, and pneumonia in several types of animals
- - Pasteurella multocida - can be transmitted to humans by dog and cat bites. Also inhabits the saliva of the Komodo dragon.
- Cause pneumonia and septicemia
Haemophilus
genus of Pasteurellales

- Small
- Gram negative
- Bacilli
- these organisms inhabit the mucous membrane of the upper respiratory tract, mouth, vagina, and intestinal tract
- Haemophilus influenze - named long ago because of the erroneous belief that it was responsible for influenza
- Haemophilus is derived from the bacterias requirement of blood in their culture medium (hemo = blood)
- Unable to synthesize important parts of the cytochrome system needed for respiration, and they obtain these substances from the hemefraction known as the X factor, of blood hemoglobin
- The culture medium must also supply the cofactor nicotinamide adenine dinucleotide ( either from NAD plus or NADP plus), which is known as V factor
- Clincial labs usually test for the requriemnt of X and V factors to identify isoaltes as Haemophilus species
- Haemophilus influenze has been responsible for several important diseases - meningitis, epiglottis, septic arthritis in children, bronchitis, and pneumonia
- Epiglottis - life threatening condition in which the epiglottis becomes infected and inflamed
- Haemophilus ducreyi - the cause of the STD chancroid
franisella
genus of pasteurellales

- F. tularensis - rabit fever
- Gram negative
- bacilli
The Epsilonproteobacteria
- slender
- gram negative
- rods - helical or curved
- two important genera - both of which are motile by means of flagella and are microaerophilic
campylobacter
- microaerophilic vibrios - each cell has one polar flagellum
- gram negative
- bacilli
- Campylobacter fetus - causes spontaneous abortion in domestic animals
- C. jejuni - leading cause of outbreaks off foodborne intestinal disease
- not an enteric
gastroenteritis
helicobacter
- gram negative
- bacilli
- microaerophilic
- curved rods
- multiple flagella
- Helicobacter pylori - identified as the most common cause of peptic ulcers in humans and a cause of stomach cancer
clostridium
- obligate anaerobes
- rod shaped cells - bacilli
- gram positive
- cells contain endospores that usually distend the cell - the formation of endospores by bacteria is important to both medicine and the food industry because of the endospores resistance to heat and many chemicals
- C. tetani - tetanus
- C. botulinum - botulism
- C. perfringes - gas gangrene
- C. difficile - caused by C. perfringes - a common form of foodborne diarrhea - an inhabitant of the intestinal tract that may cause a serious diarrhea. This occurs only when antibiotic therapy alters the normal intestinal microbiota, allowing overgrowth by toxin producing C. difficile
Bacillus
- bacteria of the genus bacillus
- typically rods that produce endospores
- common in soil
- only a few are pathogenic to humans
- several species produce antibiotics
- Bacillus antrhacis - causes anthrax - a disease of cattle, sheep, and horses that can be transmitted to humans - often mentioned as a possible agent of biological warfare
- The anthrax bacillus is a nonmotile faculatative anaerobe, often forming chains in culture. The centrally located endospore does not distend the walls
- Bacillus thuringienis - probably the best known microbial insect pathogen - it produces intracellular crystals when it sporulates
- Commercial preparations continaing endospores and crystalline toxin of this bacterium are sold in gardening supply shops to be sprayed on plants
- Bacillus cereus - a common bacterium in the environment and occasionally is identified as a cause of food poisoning, especially in starchy foods such as rice
staphylococcus
- gram positive
- cocci in clusters - grapelike
- Staphylococcus aureus - named for its yellow pigmented colonies( the yellow pigment probably confers some protection from the antimicrobial effects of sunlight)- members of this species are facultative anaerobes
- Grow comparatively well under conditions of high osmotic pressure and low moisture - which explains why they can grow and survive in nasal secretions and on the skin - also explains how S. aureus can grow in some foods with high osmotic pressure or in low moisture foods that tend to inhibit the growth of other organsims
- S. aureus produces many toxins that contribute to the bacteriums pathogeneicity by increasing its ability to invade the body or damage tissue - the infection of surgical wounds by s. aureus is a common problem in hospitals - and its ability to develop resistance quickly to such antibiotics as penicillin contributes to its danger to patients in hospital enviornments
- S. aureus produces the toxin responsible for toxic shock syndrome, a severe infection characterized by high fever and vomiting, sometimes even death
- S. aureus also produces an enterotoxin that causes vomiting and nausea when ingested; it is one of the most common causes of food poisoning
- S. epidermidis - coagulase
- S. aureus - coagulase +, beta hemolytic
lactobacillales
- the genus Lactobacillus is a representative of the industrially important lactic acid-producing bacteria
- most lack a cytochrome system and are unable to use oxygen as an electron acceptor - lack an electron transport chain
- unlike most obligate anaerobes, though, they are aerotolerant anaerobes and capable of growth in the presence of oxygen
- grow poorly
lactobacillus
- located in the vagina, intestinal tract, and oral cavity
- Lactobacilli are used commercially in the production of sauerkraut, pickles, buttermilk, and yogurt
- Typically a succession of lactobacilli, each more acid tolerant than its predecessor, participates in these lactic acid fermentations
Streptococcus
- gram positive
- cocci in chains - spherical
- catalase -
- taxonomically complex group - probably responsible for more illnesses and causing greater variety of diseases than any other group of bacteria
- pathogenic streptococci produce several extracellular substances that contribute to their pathogeniticty - among them are products that destroy phagocytic cells that ingest them
- enzymes produced by some streptococci spread infections by digesting connective tissue of the host, which may also result in extensive tissue destruction
- infections are also allowed to spread from sites of injury by enzymes that lyse the fibrin of blood clots
- a few nonpathogenic species of streptococci are important in the produce of dairy products
- S. pyogenes - beta hemolytic
- S. pneumo - alpha hemolytic, optochin sensitive
Enterococcus (enterococci)
- adapted to areas of the body that are rich in nutrients but low in oxygen, such as the gastrointestinal tract, vagina, and oral cavity
- also found in large numbers in human stool
- gram positive
- catalase -
- relatively hard microbes and therefore - persist as contaminants in a hospital environment, on hands, bedding, and even as a fecal aerosol
- in leading years they have become the leading cause of nosocomial infections, especially because of their high resistance to most antibiotics
- Enterococcus faecalis and Enterococcus faecium are respoinsbile for much of the infections of surgical wounds and the urinary tract
- In medical settings they frequently enter the bloodstream through invasive procedures, such as indwelling catheters
listeria
- Listeria monocytogenes can contaminate food, especially dairy products - survives within phagocytic cells and is capable of growth at refrigeration temps
- Gram positive
- If Listeria monocytogenes infects a pregnant woman, the organism poses the threat of stillbirth or serious damage to the fetus - meningitis in newborns
- Psychotrophic
mycoplasmatales
- highly pleomorphic because they lack a cell wall and can produce filaments that resemble fungi
- cells of the genus Mycoplasma are very small, ranging in size from 0.1 to 0.25 micrometers with a cell volume that is only about 5% of that of a typical bacillus
- Mycoplasms may represent the smallest self replicating organsims that are capable of a free living existence
- M. pneumonia - the most significant human pathogen among the mycoplasmas
- M. pneumonia - the cause of the common form of mild pneumonia (walking pneumonia)
- Mycoplasms can be grown on artificial media that provide them with sterols(if necessary) and other special nutritional or physical requriements
- Colonies are less than 1mm in diameter and have a fried egg appearance when viewed under the microscope
mycobacterium
- aerobic
- non endospore forming rods
- myco - fungus like - was derived from their occasional exhibition of filamentous growth
- acid fast staining
- drug resistance
- pathogenicity
- cell wall structurally similar to gram negative bacteria
- the outermost lipopolysaccharide layer in mycobacteria is replaced by mycolic acids - these form a waxy, water resistant layer - this makes the bacteria resistant to stresses such as drying - nutrients enter the cell through this layer very slowly which is a facter in the slow growth rate of mycobacteria
- few antimicrobial drugs are able to enter the cell
- sometimes takes weeks for visible colnoies to appear
- Mycobacterium tuberculosis - tuberculosis - slow growing - acid fast
- M. leprae - leprosy - acid fast - never cultured on artificial media
- Mycobacterium are usually separated into two groups - slow growers and fast or rapid growers which form visible colonies on appropriate media within 7 days
- Slow growing bacteria are more likely to be pathogenic to humans
- The rapid growing bacteria also contain a number of occasional, nontuberculous human pathogens which most commonly infect wounds - however these mycobacteria are more likely to be nonpathogenic soil and water microbes
Corynebacterium
- coryne - club-shaped
- pleomorphic
- morphology often varies with the age of the cells
- Corynebacterium diphtheria - the causative agent of diphtheria
Propionibacteirum
- name is derive from the organisms ability to form propionic acid; some species are important in the fermentation of swiss cheese
- anerobic
- Propionibacterium acnes - bacteria that are commonly found on human skin and are implicated as the primary bacterial cause of acne
Gardnerella
- Gardnerella vaginalis - a bacterium that causes one of the most common froms of vaginitis
- Always has been some difficulty in assigning a taxonomic position in this species, which is gram variable, and which exhibits a highly pleomorphic morphology
- Clue cells
- Gram variable
frankia
the genus Frankia causes nitrogen fixing nodules to form in alder tree roots - similar to rhizobia causing nodules on the roots of legumes
streptomyces
- the best known of the actinomycetes and is one of the bacteria most commonly isolated from soil
- the reproductive asexual spores of Streptomyces are formed at the ends of aerial filaments - if each spore lands on a suitable substrate, it is capable of germinating into a new colony
- strict aerobes
- often produce extracellular enzymes that enable them to utilize proteins, polysaccharides, and many other organic materials found in soil
- characteristically produces a gas compound called geosmin - gives fresh soil its typical musty odor
- species of Streptomyces are valuable because they produce most of our commercial antibiotics
Actinomyces
- consists of facultative anaerobes that are found in the mouth and throat of humans and animals
- occasionally form filaments that can fragement
- Actinomyces israelii - can cause actinomycosis - a tissue destroying disease that usually affects the head, neck ,or lungs
Nocardia
- morphologically resembles Actinomyces
- aerobic
- to reproduce - they form rudimentary filaments which fragment into short rods
- the structure of their cell wall resembles that of the mycobacteria; therefore, they are often acid fast
- species are common in soil
- Nocardia asteroids - occasionaly cause a chroni, difficult to treat pulmonary infection - one of the causative agents of mycetoma - a localized destructive infection of the feet or hands
Chlamydia and Chlamydophila
- gram negative
- coccoid bacteria
- elementary body which is the infective agent
- do not require insects or ticks for transmission - the yare transmitted to humans by interpersonal contact or by airborne respiratory routes
- the chlamydias can be cultivated in lab animals, cell cultures, or in the yolk sac of embryonated chicken eggs
- C. trachomatis - the best known pathogen of the group of responsible for more than one major disease - these include trachoma - one of the most common causes of blindness in humans in the less developed countries - also considered to be the primary causative agent of both nongonococcal urethritis, which may be the most common sexually transmitted disease in the U.S., and lymphogranuloma venereum, another sexually transmitted disease
- C. psittaci - the causative agent of the respiratory disease psittacosis
- C. pneumonia - the cause of a mild for of pneumonia that is especially prevalent in young adults
Spirochaetes
- spirochetes have a coiled morphology, resembling a metal spring - some are more tightly coiled than others
- method of motility - makes use of two ore more axial filaments ( or endoflagella) enclosed in the space between an outer sheath and the body of the cell
- one end of each axial filament is attached near a pole of the cell - by rotating its axial filament, the cell rotates in the opposite direction, like a corkscrew, which is very efficient in moving the organisms through liquids
- many spirochetes are found in the human oral cavity and are probably among the first microorganisms described by van Leeuwenhoek in the 1600s that he found in saliva and tooth scrapings
- an extraordinary location for spirocehtes is on the surfaces of some of the cellulose digesting protozoa found in termites, where they may function as substitues for flagella
Treponema
- The best known pathogenic material of the spirochetes
- Treponema pallidum - the cause of syphilis
Borrelia
- Members of the genus Borrelia cause relapsing fever and Lyme disease - serious diseases that are usually transmitted by ticks or lice
Leptospira
- Leptospirosis is a disease usually spread to humans by water contaminated by Leptospira species
- The bacteria are excreted in the urine of such animals as dogs, rats, and swine, so domestic dogs and cats are routinely immunized against leptospriosos
- Tightly coiled cells
Bacteroides
- from the genus of Bacteroidetes
- live in the human intestinal tract in numbers approaching 1 billion per gram of feces
- some also reside in anaerobic habitats such as the gingival crevice and are also frequently recovered from deep tissue infections
- gram negative
- nonmotile
- do not form from endospores
- infections caused by Bacteroides often result from puncture wounds or surgery and are a frequent cause of peritonitis - an inflammation resulting from a perforated bowel
Fusobacterium
- from the genus fusobacteria
- long and slender
- gram negative
- rods with pointed rather than blunt ends
- in humans, the yare found most often in the gingival crevice of the gums and may be responsible for some dental abscesses (dental disease)
opportunistic fungi - ascomycetes
aspergillus
opportunistic fungi - zygomycetes
rhizopus
opportunistic fungi - basidiomycytes
cryptoccus neoformans

dimorphic
systemic fungi - histoplasmosis
histoplasma capsulatum

dimorphic
systemic fungi - coccidiomycosis
coccidiomycosis immitis

dimorphic
systemic fungi - blastomycosis
blastomyces dermatitidis

dimorphic
subcutaneous fungi - sporotrichosis
sporothrix schenckii
superficial fungi - dermatophytes (hair,skin,nails)
microsporum
epidermophyton
tirchophyton
protozoa - trichomonas vaginalis
vagina

female and able urinary tracts

asymptomatic
protozoa - giardia lambia
diarrhea
protozoa - entamoeba histolytic
diarreha
protozoa - plasmodium sp. P. vivax, P. ovale, P. malariae, P. falciparium (most dangerous)
definitive host - mosquito

intermediate host - humans
protozoa - trypanosoma brucei gambiense
african sleeping sickness

transmitted by the tsetse fly

antigenic variation
protozoa - trpanosoma cruzi
chagas disease

transmitted by the reduvid bug

antigenic variation
helminths - flatworm - flukes
long fluke - paragonimus westermani

blood fluke - schistosoma sp.
helminths - flatworms - tapeworm
beef tapeworm - taenia saginata

human - definitive host


echinococcus granulosis - dogs, wolves, foxes

human - intermediate host
nematodes or roundworm - hookworm
necator americanus

infects humans
nematodes or roundworm - heartworm
dirofilaria immitis

infects dogs, and cats
nematodes or roundworm - pinworm
enterobisu vermicularis

infects humans
nematodes or roundworm - ascariasis
ascaris lumbricoides

infects humans
nematodes or roundworm - trichinellosis
trichinella spiralis

infects humans and animals
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