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Aerobic and Facultative Gram-positive
Rods
infrequently cause human infections in the USA Bacillus cereus / food poisoningBacillus anthracis / anthraxCorynebacterium diphtheriae / diphtheriaListeria monocytogenes / listeriosis most frequent and significant cause of disease in the USA by a facultative Gram-positive rod shaped bacteria Nocardia asteroides aerobic filamentous Gram-positive rod / also stains acid-fast natural habitat / soil infections in immunocompromised individuals primarily pulmonary infections that may disseminate TERM 2
Corynebacterium diphtheriae
DEFINITION 2 Gram-positive pleomorphic rod aerobic, facultative, or anaerobic depending on species- palisades or "Chinese letters"habitat is upper respiratory tract - spread by "droplet nuclei"Diphtheria - grayish pseudomembrane covering tonsils, pharynx, larynx - exotoxin / inhibits protein synthesis - tox gene carried by bacteriophage diagnosis - based primarily on clinical signsisolation of C. diphtheriae & demonstration of toxin production TERM 3
Corynebacterium diphtheriae - prevention
DEFINITION 3
There have been no reported cases of respiratory diphtheria
in the US for 7 years (since 2004). Routine immunization
with TDaP vaccine & boosters
TERM 4
Corynebacterium diphtheriae -treatment /
prevention
DEFINITION 4 Diphtheria treatment - antitoxin - penicillin or erythromycin prevention - immunization w/ toxoid (DTaP vaccine) - immunization is very effective - endemic/epidemic in some parts of world effect of vaccine curtailment prior to breakup low incidence in former USSR presently immunization re- instituted in many areas TERM 5
Listeria monocytogenes - identification
DEFINITION 5
Gram-positive pleomorphic
rodnonsporeformingmotilenarrow zone of beta-
hemolysispathogenic strains / listeriolysin-
OUbiquitous in nature soil, water, produce, milk products,
processed meats feces of mammals, including humans &
birds
Epidemiology of Listeriosis
Transmission
animal contact
contaminated food (~1981)
transplacental
Healthy people rarely develop severe illness (0.
cases/100,000) At risk populations pregnant women (1/
of cases, ~20X risk) unborns & newborns
immunocompromised (HIV 100-200X risk) elderly
TERM 7
Symptoms / Manifestations of Listeriosis
DEFINITION 7 1-6 weeks post-exposureflu-like symptoms w/ fevernausea, vomiting, & diarrhea septicemia (50% fatality) meningitis/encephalitis (50-80% fatality) endocarditis premature delivery (50%)spontaneous abortion / stillbirth (5%)Diagnosis by culture blood, CSF, or otherwise sterile site TERM 8
Intracellular pathogenesis of Listeria
monocytogenes
DEFINITION 8 enters bloodstream phagocytosis by macrophages & PMNs entry into epithelial cells & hepatocytes acidity of phagolysosome activates listeriolysin-O lyses phagolysome escapes into cytoplasm & multiplies recruits & polarizes actin filaments actin rockets push against host cell surface (listeriopods)bacteria- laden listeriopods ingested by adjacent cells TERM 9
Treatment & Prevention of
Listeriosis
DEFINITION 9
Penicillin/ampicillin (w/ gentamycin Trimethoprim-
sulfamethoxazole Cook foods wellAvoid high risk foods Risk
Foods
raw & pasteurized dairy products
raw/undercooked vegetables
raw/undercooked meats & fish
Growth at refrigerated temperatures No vaccine
TERM 10
ANAEROBIC BACTERIA
DEFINITION 10 (1) prominent members of normal microbiota usually nonpathogenic in their "proper" habitatcommon causes of abscesses and wound infections gain entry to the blood and tissuesopportunistic anaerobic infections / "mixed infections"(2) other anaerobic bacteria / not normal flora of humans exogenous pathogens e.g. Costridium tetani & Clostridium botulinumproduce severe and often fatal diseases exotoxins / among the most powerful poisons known / 1g may be fatal
Tetanus
spores germinate in tissue at wound siteproduce exotoxin tetanus toxin (tetanospasim) a neurotoxin blocks release of inhibitory mediators at spinal synapses Symptoms 3 to 7 days after acute wounddifficulty swallowing & opening mouth trismus: spasms of the masseter musclesgeneralized severe muscle spasms ,respiratory distress & failure (~ 60% of cases require ventillation) TERM 17
Tetanus - Prevention and Treatment
DEFINITION 17 (a) prophylactic (prior to wound) immunization / tetanus toxoid (DTaP) primary immunizations @ 2, 4, & 6 months booster @ 12- months, 4-6 years, and every 10yrs (b) prophylactic (after wound prior to symptoms) depends on immune status(1) properly immunized patient wound cleaning & penicillin / tetanus toxoid if > 5 years since booster(2) unknown or unimmunized patient wound cleaning & penicillin /tetanus toxoid & tetanus immune globulin TERM 18
Tetanus - Prevention and Treatment
continued
DEFINITION 18 (c) when symptoms of tetanus are already present wound cleaning & penicillin tetanus immune globulin tetanus toxoid muscle relaxants / ventilation / respiratory supportneonatal tetanus / umbilical stump infection ~ 1/3 of neonatal deaths~50% of cases in > 50 year oldsunimmunized immigrants (majority of other cases) TERM 19
Clostridium botulinum
DEFINITION 19 spores widely distributed in soil Botulinum toxin a neurotoxin blocks release of acetylcholine result is flaccid paralysisTypes of botulism Foodbourne - ingestion of exotoxin in contaminated foodWound - in situ production exotoxin in colonized woundInfant transient production of exotoxin in gastrointestinal tractTreatment-associated - by injection of pharmacologic preparations of exotoxin TERM 20
FOODBOURNE BOTULISM
DEFINITION 20
food intoxication / poisoning spores present on
vegetables & meats - inadequate canning or vacuum packing
- inadequate food storagespores germinate in food produce
botulinum toxin
FOODBOURNE BOTULISM - Symptoms
Symptoms 1 to 4 days after ingestion of intoxicated food
double vision (diplopia) difficulty swallowing (dysphagia)
developing weakness and flaccid paralysis respiratory &/or
cardiac failure
TERM 22
FOODBOURNE BOTULISM -Treatment /
Prevention
DEFINITION 22
Prevention: proper canningtoxin is heat-labile /
destroyed @100C for 20 min. Treatment: trivalent
antitoxin (types A, B, & E) respiratory support wound
cleaning & penicillin (wound botulism) Mortality rate: ~65%
untreated, ~ 25% treated
TERM 23
-Infant Botulism - Wound Botulism
DEFINITION 23 (2) infant botulism (an infection) - ingestion of spores in raw/unpasteurized foods(raw honey) - spores germinate in gut and produce exotoxinMost common form of botulism in US ~70% of total cases. Cases are sporadic. Honey is the only known risk factor to date, (3) wound botulism (an infection) -spores contaminate wound -spores germinate in wound and produce exotoxin Wound botulism occur almost exclusively (~96%) among injection- drug users in the western United States and is associated with black-tar heroin TERM 24
Clostridium perfringens -food poisoning
DEFINITION 24 present in soil, intestinal and vaginal tract Diseases(1) food intoxication/poisoning? infection? spores associated with food survive cooking germinate in large numbers in "left-over" foods after ingestion sporulation in gut - enterotoxinsymptoms 8-16 hours incubation period watery diarrhea & cramps (resolves w/i ~ 24 hours) TERM 25
Clostridium perfringens -gas gangrene
DEFINITION 25 gas gangrene (an infection) predisposing conditions - trauma (deep wounds, auto accident) - abortion bacterial growth at site of injury / produce exotoxins - alpa-toxin most important a lecithinase - damages cell membranes symptoms pain, edema, gas in tissue often hemolysis & jaundice septic shock & death treatment penicillin & wound management
