SJSU MICR20 SJSU CHATER 20

gram-negative bacilli

- non-spore forming bacteria

- range of habitats: large intestines, zoonotic, respiratory, soil, water

- outer membrane LPS (endotoxin)

opportunistic gram- bacilli

Pseudomonas & Burkholderia

zoonotic pathogens gram- Bacilli

Brucella & Francisella

human pathogens

Bordetella & Legionella

aerobes ferment carbohydrates

false

facultative anaerobes ferment carbohydrates

true

lactose fermenters

- Escherichia

- Klesiella

- Citrobacter

- Enterobacter

oxidose-negative

- Salmonella

- Shigella

- Proteus

- Serratia

- Yersinia

oxidase positive

- Haemophilus

- Pasteurella

Pseudomonas aeruginosa pathogen

- skin/skeletal: complication of burns, skin rashes

- nervous/muscle: corneal ulcers, meningitis

- cardiovascular/lymphatic/systemic: endocarditis

- respiratory: complication of cystic fibrosis

- urogenital: UTI

Bordetella pertussis pathogen

- whooping cough (communicable childhood affliction

- acute respiratory syndrome

- often severe, life-threatening complications in babies

Escherichia coli pathogen

- gastrointestinal: acute diarrhea

- urogenital: UTI

Escherichia coli O157:H7

- gastrointestinal: acute diarrhea

- urogenital: hemolytic uremic syndrome

Pseudomonas

- small gram- rods w/ single polar flagellum

- primary in soil, sea water & fresh water

- important decomposers & bioremediators

- frequent contaminants in homes & clinical settings

- aerobic respiration (doesn't ferment carbohydrates

- oxidase & catalase positive

- produce water soluble pigments

Pseudomonas aeruginosa

- common in soil & water

- intestinal resident in 10% of people

- resistant to soap, dyes, quaternary ammonium disinfectants, drugs (multidrug), drying

- frequent contaminant in ventilators, IV solutions, anesthesia equipment

- opportunistic pathogen

- grapelike odor & green-blue pigment (pyocyanin)

Bordetella pertussis

- encapsulated coccobacillus

- reservoir: healthy carriers

- transmission by direct contact or inhalation of aerosols

- vaccine: DTaP

Bordetella pertussis virulence factors

- Receptors that recognize and bind to ciliated respiratory epithelial cells

- Toxins that destroy and dislodge ciliated cells

- loss of ciliary mechanism leads to buildup of mucus & blockage of airways

Genus Alcaligenes

- live in soil & water

- may become normal flora

- Alcaligenes faecalis is most common clinical species

Legionella pneumophila

- distributed in water, in close association w/ amoebas

- outbreak in 1976

Legionellosis

- Legionnaires' disease (most severe) & Pontiac fever

- prevalent in males over 50

- nosocomial disease in elderly patients

- not contagious

- fever, cough, diarrhea, & abdominal pain

- treatment: Levofloxacin or Azithromycin

Family Enterobacteriaceae

- gram- bacteria

- small, non-spore forming rods

- inhabit soil, water, decaying matter

- most frequent cause of diarrhea through enterotoxins

characteristics of Enterbacteriaceae

- glucose ferment

- nitrate reduction

- oxidase negative

- presence of flagella

- regular, straight rods

- coliforms & non-coliforms

Virulence factor: H

flagellar antigen

virulence factor: K

capsule and/or fimbrial antigen

virulence factor: O

somatic or cell wall antigen

antigen structure & virulence factor

- complex surface antigen contribute to pathogenicity & trigger immune response

- not all species carry H & K antigens, but all have O (endotoxic shock)

Escherichia coli

- most common aerobic & non-fastidious in gut

- pathogenic strain grouped as: Enterohemorrhagic E. coli & Enterotoxigenic E. coli

Enterohemorrhagic E. coli (EHEC)

hemorrhagic syndrome & kidney damage

Enterotoxigenic E. coli (ETEC)

- severe diarrhea due to heat-labile toxin & heat-stable toxin

- stimulate secretion & fluid loss

- has fimbriae

clinical cases of E. coli

- most clinical diseases transmitted exclusively among humans

- cause infantile diarrhea, traveler's diarrhea, UTI

- oral antimicrobics may be effective in early infection

E. coli O157:H7

- virulence due to cell wall receptor that fuse w/ host cell membrane & create direct port that bacteria secrete toxins from

- toxins enter host cell, binds ribosomes & disrupt protein synthesis, leading to death & shedding of intestinal cells

Klebsiella pneumoniae

- normal inhabitant of respiratory tract

- large capsule

- cause of nosocomial pneumonia, meningitis, bacteremia, wound infections, & UTI

Enterobacter sp. pathogen

UTI & surgical wounds

Citrobacter sp. pathogen

opportunistic UTI & bacteremia

Serratia marcescens

- produce red pigment

- causes pneumonia, burn & wound infections, septicemia, & meningitis

Proteus sp.

- swarm on surface of moist agar in a concentric pattern

- UTI, wound infections, pneumonia, septicemia, & infant diarrhea

Salmonella bongori

- found almost exclusively in cold-blooded animal

Salmonella enterica

- divided into 6 subspecies (enterica, salamae, arizonae, diarizonae, houtenae, indica)

typhoid fever

- caused by Salmonella serotype Typhi

- Bacillus enters w/ ingestion of food or water contaminated by feces

- asymptomatic carriers; some chronic carriers shed bacilli from gallbladder

- Bacilli adhere to small intestine, cause invasive diarrhea that leads to septicemia

- treatment with ciprofloxacin or ceftriaxone

- 2 vaccines for temporary protection

Shigellosis

- common incapacitating dysentery

- fever, nausea, painful abdominal cramps, & frequent defecation of watery stool filled w/ mucus & blood

- cause: S. dysenteriae, S. sonnei, S. flexneri, & S. boydii

- invade villus of LI, does not perforate intestine or invade blood

- enters Peyer's patches instigate inflammatory response; endotoxin & exotoxin

- treatment: fluid replacement & ciprofloxacin & sulfatrimethoprim

Yersinia enterocolitica

- domestic & wild animals, fish, fruits, vegetables, & water

- bacteria enter SI mucosa, or lymphatic

- survive in phagocytes

- inflammation of ileum can mimic appendicitis

Yersinia pseudotuberculosis

- infection similar to Y. enterocolitica, but w/ more lymph node inflammation

Yersinia pestis

- nonenteric bacteria

- tiny, gram- rod, unusual bipolar staining & capsule

- virulence factors: capsular & envelope proteins protect against phagocytosis & foster intracellular growth

- coagulase, endotoxin, murine toxin

Plague

- humans develop plague through contact w/ wild animals (sylvatic plague), domestic (urban plague), or infected humans

- found in 200 species of mammals - rodents, without causing disease

- flea vectors: bacteria replicates in gut, coagulase causes blood clotting that blocks esophagus; flea becomes ravenous

pathology of plague

- infectious dose: 3-50 bacilli

- infection leads to: Bubonic plague, Septicemic plague, or Pneumonic plague

Bubonic plague

- bacillus multiplies in flea bite

- enters lymph

- causes necrosis & swelling of lymph nodes (called a bubo) in groin or axilla

Septicemic plague

- progression to massive bacterial growth

- virulence factors cause intravascular coagulation, subcutaneous hemorrhage, & purpura (black plague)

Pneumonic plague

- infection localized to lungs

- highly contagious

- fatal w/o treatment

diagnosis of plague

depends on history, symptoms, & lab findings from aspiration of buboes

treatment of plague

- streptomycin, tetracycline, or chloramphenicol

- killed or attenuated vaccine available

prevention of plague

by quarantine & control of rodent pop. in human habitats

Haemophilus

- blood-loving Bacilli

- tiny, gram- pleomorphic rods, fastidious

- sensitive to drying, temp. extremes, & disinfectants

- none can grow on blood agar w/o special techniques; requires hemin, NAD, or NADP

Haemophilus influenzae

- acute bacterial meningitis, epiglottis, otitis media, sinusitis, pneumonia, & bronchitis

Haemophilus ducreyi

cause of chancroid STD

Haemophilus parainfluenzae & Haemophilus aphrophilus

- members of normal oral & nasopharyngeal flora

- involved in infective endocarditis

sylvatic plague

- found in wild rodent population, in rural or semi-rural areas

- vector: fleas that infestwild rodents

- transmission: affects wild animal pop., but can transmit to humans

Urban plague

- occurs in urban areas, affecting domestic animals & human pop.

- vectors: fleas that infest domestic rodents, such as rats & mice

- transmission: rodents to humans, especially in crowded livnig conditions w/ high rodent pop.

- distributed in cities