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Gram (+) Bacilli – Flashcards

Lewis Edwards

7 July 2022

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Clostridium species

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Soil bacterium
Obligate Anaerobes
Spore formers
Do not have enzymes to protect from free radicals and superoxides

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Clostridium botulinum
Occurrence

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Botulism
Cosmopolitan.
Poor canning processes, food not cooked sufficiently to kill spores.
Vegetative cells can then produce NEUROTOXIN (acts at the neuromuscular junction, prevents ACh from binding so muscle cannot contract-flaccid) under anaerobic conditions.
Commerical canning cases are rare, more common in low acid or alkaline foods.
Toxin destroyed by boiling vigorously for 3 minutes. (b/c it is a protein)

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Clostridium botulinum
Reservoir

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Soil bacterium
Intestinal tract of some herbivores and fish

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Clostridium botulinum
MOT & IP

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MOT: Ingestion of preformed NEUROTOXIN without adequate heating during the canning process or before eating.

IP: 1-4 days; shorter IP= worst case scenario & deaths

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Clostridium botulinum
Disease process (DP) & Signs/Symptoms

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DP: affects nervous system primarily especially neuromuscular junction (NMJ)
Usually an INTOXICATION and NOT an infection!
SN/SX: ptosis (droopy eyelids), blurred vision & dry mouth are first SX. Descending symmetrical FLACCID PARALYSIS in ALERT person.
Without treatment, 33% die in 3-7 days of respiratory paralysis; Good treatment 15% die

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Clostridium botulinum
Diagnosis (DX) & Treatment (TX) & Prophy

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DX: Detection of toxin is most important b/c spores are so common
TX: Respiratory support; botulism antitoxin
RX: PCN in infants b/c it is an INFECTION in them (intoxication in adults)
NO immunity
Prophy: Can foods at proper temperature, pressure, & adequate time.; Boil home canned vegetables with stirring for at least 3 minutes

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Clostridium botulinum
Wound Botulism

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Rarest type
Spores contaminate ANAEROBIC wound (eg. puncture) and germinate.
Vegetative cells produce exotoxin & cause disease.
May occur in neonate if cord is cut with unsterile instrument.

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Clostridium botulinum
Infant Botulism

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1st recognized in 1976.
Occurs in infants under 12 months resulting in flaccid paralysis (floppy baby sydnrome)
Spores ingested (raw honey) & germinate in gut.= INFECTION b/c they do not have as many coliform bacteria as adults do to fight it.
Accounts for 5% of SIDS.
TX: Respiratory support, botulinum antitoxin, PCN to kill vegetative cells

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Clostridium tetani
Occurrence

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Tetanus (Lockjaw)
Infection that is rare in US 50-90 cases/yr.
Common in Asia, Africa, South America 500,000 cases/yr.

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Clostridium tetani
Reservoir & MOT

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Res: Intestine of animals including Homo sapiens (normal harmless inhabitant); soil contaminated with feces mainly herbivores.
Not very invasive- does not get through gut wall.
MOT: Introduction of spores usually through puncture wounds, IV drug use, but trivial injuries are rarely at risk.

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Clostridum tetani
IP & CFR

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IP: 3-21 days, may be months; Short IP=worst case scenario
CFR (case fatality rate) =30-90%

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Clostridium tetani
Disease Process

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Spores germinate in anaerobic wounds. Vegetative cells produce TETANOSPASMIN (exotoxin) which is absorbed into neurons from MEP then migrates through the nerves to CNS. Tetanospasmin binds to neurons preventing release of inhibitory neurotransmitters (GABA & Glycine). Results in uncontrolled contractions of muscles especially masseter (b/c nerves are short).
Tetanus neonatorium may occur in neonates if umbillical cord or circumcision are done with non-sterile instruments.

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Clostridium tetani
TX, Immunity, & Prophylaxis

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TX: respiratory support, antitoxin to neuralize toxin (=Tetanus Immune Globin)
RX: PCN to kill any vegetative cells so there is no more source of toxin.
Imm: Tetanus toxoid provides immunity for 10 years. Usually first given to kids 7+ as DTaP (Diphtheria, Tetanus and Pertussus). Need booster every 10 years or if high risk injury occurs. Today recommendation is for Td for anyone over 7 years old.
Prophy: Incidence is low b/c schools require vaccination.

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Clostridium perfringens
Cause

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Gas Gangrene & food poisoning
Anaerobic wound contaminated with spores from soil or animal feces.
Vegetative cells produce enzymes that kill & digest host tissues.
Bacteria ferment CHO in necrotic tissues (esp. muscle tissue b/c there is lots of glycogen which is a CHO).
Gases produced as result of fermentation, may rip & tear tissues. Bacteria spread through tissues so affected area enlarges.
Associated with corned beef.

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Clostridium perfringens
TX

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Wound debridement
Surgical removal of foreign objects and necrotic tissues
Antitoxins
May use Hyperbaric Chamber to push O into cells @ extreme pressure & Oxygen (kills bacterium b/c it is an obligate anaerobe).

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Clostridium difficile

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(C. diff)
Major problem in hospitals or in people who have to take antibiotics for a long period of time

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Bacillus anthracis

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Anthrax
Gram (+) bacillus
Encapsulated
Spore-forming
Non-motile
Facultative anaerobe- most obligate aerobes
Koch used this bacterium as his model to develop his postulates
Pasteur used it to prove the need for vaccinations

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Bacillus anthracis
Occurrence

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Most cases occur in herbivores from Africa, Asia, Haiti & Middle Eastern countries
Products like animal hides may contain spores
In US less than 10 human cases/yr. due to effective control measures but epizootic outbreaks occur regularly.
The practice of vaccinating workers involved in industrial processing of imported animal products & decline of using fibers of animal origin are primary factors in the current low incidence of human anthrax in US.

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Bacillus anthracis
MOT, IP, & Resevoir

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MOT: Direct contact with broken skin, inhalation, or ingestion
IP: 2-5 days
Res: Soil, infected domestic herbivorous animals or their hides

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Bacillus anthracis
Cutaneous Anthrax

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95% of human infections are of this type.
Exposure of broken skin to contaminated soil, infected animal hides, goat hair, wool, etc.
SN/SX: Painless papule (slightly raised area) progressing to an ulcer then to a black lesion called an ESCHAR
CFR: If no TX, 20% will die

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Bacillus anthracis
Pulmonary Anthrax

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a.k.a. Woolsorter's Disease
Inhaled spores germinate in lungs
Vegetative cells grow ; produce exotoxins resulting in toxemia causing capillary thrombosis and cardiovascular shock.;
Septicemia causes death within a few hours.
Regardless of TX with antibiotics, this form is virtually always fatal b/c of effect of the exotoxins

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Bacillus anthracis
Gastrointestinal Anthrax

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Rarest form of disease ; has not been reported in the US
Occurs in underdeveloped countries when food (milk, cheese, meat) contaminated with spores is ingested.
Exotoxin produced in the digestive tract causes necrotic lesions of ileum and/or L.I.
CFR 25-50%
If bacterium reaches the lymph ;/or bloodstream, fatal septicemia develops within hours

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Bacillus anthracis
Virulence factors ; DX

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A polypeptide capsule which prevents phagocytosis and an exotoxin which is a combo. of 3 proteins: EF (edema factor-increases capillary permeability), PA (protective antigen), and LF (lethal factor).
The exotoxin also helps prevent phagocytosis
DX: The bacterium can be cultured from soil, cutaneous lesions, respiratory tract or blood. Determine the presence of exotoxin.

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Bacillus anthracis
RX, Imm., ; Prophylaxis

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RX: Cipro, PCN, Doxycycline, Erythromycin
Immunity: Permanent with recovery; Toxoid avail. for humans which is a surface protein of the bacterium. A live, avirulent spore (Sterne strain) vaccine is used to vaccinate livestock animals.
Prophy: Sterilization of hides, hair ; bone products of herbivorous livestock; burn carcasses of livestock that die of anthrax; administer immunization to susceptible hosts.

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Corynebacterium diphtheria

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Diphtheria
Occ:Unimmunized kids younger than 15. US 4 cases/yr. from 1980-83
Res: Humans
MOT: aerosols (eg. sneezing)
SN/SX: Bacteria grow on mucous mem. of nose ; pharynx causing a PSEUDOMEMBRANE that consists of bacteria, epithelial cells ; WBCs to form in pharynx. Exotoxin causes destruction of cells of heart ; kidney
TX: PCN, antitoxin
Imm: DPT vacc. as a child (schools require). Booster in form of Td.

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Mycobacterium leprae

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Leprosy or Hansen's disease
11 million cases worldwide; US 200-300/yr. -- 84% HI, CA, NY, TX (Endemic in Hawaii)
Leprosarium in Carville, LA (closed in 2001)
Res: Humans & Dasypus novemcinctus (9-banded armadillo)
MOT: Repeated direct contact- communicable (hard to get)
IP: 3-5 years+
OBLIGATE INTRACELLUAR PARASITE

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Mycobacterium leprae
SN/SX, Types

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SN/SX: Bacterium invades skin & Schwann cells (form myelin sheath in PNS)
Tuberculoid (neural) leprosy: Type 4 Hypersensitivity (Delayed type) to surface Ag of bacterium resulting in nerve damage and loss of skin sensations. Very mild form of the disease.
Lepromatous (progressive) disease: occurs when hypersensitivity reaction is weak or absent. Bacterium grows in skin destroying fingers, toes, face, etc.

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Mycobacterium leprae
DX & TX

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DX: Identification of Acid-Fast bacilli from lesions, won't grow in culture, LEPTOMIN test (similar to TB skin test)
TX: Dapsone (sulfa drug)- 1940s; Rifampin- 1960s; Clofazimine
Notorious for resistance to antibiotics, so Rifampin is restricted for Mycobacterium sp. and a couple of other things ONLY!
NO immunity

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Mycobacterium tuberculosis
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Tuberculosis
4-5 million die each year worldwide; 24,000 new cases/yr. in US
Occurs from crowded living conditions, poor nutrition, and lack of drugs.
Incidence in US increasing slowly b/c of AIDS.
Most susceptible groups= kids under 5 (underdeveloped immune system), aged, AIDS
Res: M. tuberculosis= humans; M. bovis= cows; M. avium= birds
MOT: Aerosols, broken skin/ mucous membrane, raw milk (causes intestinal infection)
IP: 1-3 months

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Mycobacterium tuberculosis
DP ,SN/SX, Types

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May infect any body tissue: lungs if inhaled (most common), gut if ingested
Spreads from gut through lymphatics to anywhere.
Cell-mediated Immunity is most important response by immune system (= Type 4 (Delayed) Hypersensitivity Reaction).;
Chronic, granulomatous disease:;body responds to inflammation by producing CT to wall-off the infected area- called a tubercle.
Primary TB:;the tubercles

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Mycobacterium tuberculosis
DX, TX, Imm.

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Chest X-ray (for tubercles); TB Skin Test: PPD (Purified tuberculin Protein Derivative) which is injected in skin ; will cause intense inflammatory response in those who have or have had TB. This test not good in first 3-7 wks. of disease- have to culture sputum.
TX: Isoniazid (INH)-1954 specific for TB; Streptomycin-1950; Rifampin-1960s *main drug to treat TB
Before Rifampin it took 18-24 mo. now 6-9 mo.
Microbe is very resistant to antibiotics so they use 2-3 drugs at the same time. Hospitalization not necessary today.
Imm: vaccine available but no recommended in US b/c no longer able to do TB skin test as DX aide, instead give INH prophy if someone close to you gets disease.

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Listeria monocytogenes

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Listeriosis
Discovered in 1926, found in gut of up to 10% humans, as well as 37 mammal ; 17 avian species
INTRACELLULAR parasite causing rare sporadic outbreaks.
MOT: ingesting contaminated foods: deli meats, soft cheeses, raw milk
In healthy individuals causes flu-like SX but may spread causing septicemia (CFR 50%), meningitis (CFR 70%)
Pregnant women 20x more likely to suffer disease resulting in 80% fetal mortality. Immune suppressed, cancer (esp. leukemia), diabetes mellitus ; elderly are very susceptible
TX: ampicillin gentamicin, TMP-SMX (sulfa drug), LISTEX (a just approved bacteriophage to control ;the bacterium in soft cheeses.

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Propionibacterium acnes

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A major problem in acne

Gram (+) Bacilli – Flashcards

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