1. Gram + Bacilli: Spore-forming (Bacillus & Clostridium), and Non-spore forming (Listeria, Corynebacterium, Mycobacteria)
Nestor T. Hilvano, M.D., M.P.H.

2. Learning Objectives You should be able to:
Describe three clinical manifestations of Bacillus anthracis and identify its diagnosis and prevention.
Identify the mechanisms of pathogenicity, diagnosis, treatment, and prevention of Clostridium perfringens.
Contrast three manifestations of botulism poisoning and its treatment and prevention.
Describe the epidemiology, treatment, and prevention of tetanus.
Discuss Listeria monocytogenes as to its pathogenicity, infections, diagnosis, treatment, and prevention.
Characterize Corynebacterium as to morphology, transmission, disease, diagnosis, treatment, and prevention.
Characterize mycobacteria in terms of cell wall composition, growth rate, and resistance to antimicrobial drugs.
Describe the transmission of Mycobacterium tuberculosis and discuss diagnosis, treatment, and prevention of tuberculosis.
Compare and contrast tuberculoid leprosy with lepromatous leprosy.
Discuss the diagnosis, treatment, and prevention of leprosy.

3. Bacillus anthracis
Facultative anaerobe; gm + rod, central endospore; peritrichous
Transmission= endospore from infected animals
3 Clinical manifestations
Cutaneous anthrax – solid, painless
nodule; eschar (crusty ulcer); 20% fatal
2. Inhalation anthrax – airborne
endospores; produce toxemia
(fever, labored breathing, shock);
100% die untreated; 50% fatal (even w/ Rx)
GIT anthrax – rare in human; intestinal bleeding
Prevention – vaccination of livestock
Does steaming of mails suspected with anthrax contamination prevents the spread of infection?

4. Clostridium
Soil, water, sewage, and GIT of humans and animals; anaerobes; gm + rod
Pathogenicity- endospore survive; vegetative cells secrete toxins (histolytic toxins, enterotoxins, & neurotoxins)
C. perfringens – isolated from clinical specimens; toxins lyse blood cells; common cause of food poisoning in U.S. and gas gangrene; over 40% fatal even w/ Rx; Prevention = refrigeration and reheating, proper cleaning of wound
C. difficile - opportunistic pathogens in patients Rx w/ broad spectrum antibiotics; release toxins and enzyme hyaluronidase; hemorrhagic necrosis of intestine; pseudomembranous colitis (antibiotic -associated diarrhea)

5. Clostridium botulinum
soil and water; improper canning of food
Exotoxin = neurotoxin, blocks acetylcholine release in cholinergic
synapses (CNS/PNS)- muscle weakness (muscles can’t contract)
Food-borne botulism –
ingestion of contaminated food, exotoxin absorbed into blood (incubation less than 24 hrs., 10 ug fatal), death within few hours to 1 week (60-70% fatal); recovery of 6 to 8 months
- Symptoms = vomiting, constipation, double vision, thirst, thick saliva, paralysis of pharynx/diaphragm
- Prevention: strict hygienic canning
- Rx: Antitoxin
Infant botulism from ingestion of endospores (paralysis & death rare)
Wound botulism - endospores germinate in wounds

6. Clostridium tetani Gm +, anaerobic,with terminal endospore
in soil, dust, feces
tetanus toxin (neurotoxin) – affects AHC of spinal cord, interferes w/ inhibitory signal to muscles causing sustained contract →rigidity of muscles (locked jaw, bend back)
tetanolysin = hemolytic

7. Causes, Prevention, & Rx of Tetanus
Common in non-immunized children, after abortions, septic deliveries, infection of umbilical cord
Prevention
– tetanus toxoids (deactivated tetanus toxins; immunogenic to prevent tetanus);
- DPT vaccines
Treatment
- antitoxin; antibiotics

8. Listeria monocytogenes
Listeriosis
Gm +, non-endospore forming coccobacilli
Intracellular in macrophages
MOT: human to human; transfer of agent from pregnant woman to fetuses
Pathogenicity
- From animal/human feces, soil, water, food
- rarely symptomatics or mild flulike illness
- sepsis/ meningitis in immunocompromised
- spontaneous abortion, stillbirth, or meningitis in newborn
(lead to brain damage or death, 60%)
Rx – penicillin

9. Corynebacterium diptheria
Gm + rod, V shaped/ palisade, non-endospore-forming, aerobic
Droplets inhalation
Toxin = resp. for S/Sx
- necrosis of epithelium, leakage of exudates, pseudomembrane formation (necrotic epith. + C. d. + proteins)
- swelling, dislodged pseudomembrane
- obstruction, suffocation
Complication affect kidney, heart, and nerves
Dx. – Immunodiffusion assay (Elek test)
Rx. – antitoxin (horse serum), penicillin or erythromycin
Prev. – DPT shots (2,4,6 months; booster every 10 yrs.)

10. Mycobacterium tuberculosis
Waxy lipid (mycolic acid) cell wall; slender rods (AFB)
>50,000 new cases/yr.; 10,000 deaths/yr.
Deep inhalation of organisms; droplet (5um) w/ 1-3 bacilli
Tubercle/granuloma formation
- phagocytosis by macrophages
- intracellular multiplication
- macrophage bursting
- ingestion of TB by macrophages
- fibroblast proliferation,
recruitment of lymphocytes, walling off by fibroblasts
- caseous necrosis (cheeselike due to release of proteins + fats from
dying cells) → cavity formation; macrophage fusion
- calcification

11. M. Tuberculosis Primary TB – remain in lungs, tubercles formed
Secondary (reactivated) TB – ruptured tubercles reestablished an active infection
Disseminated (miliary) TB – variety of sites
Diagnosis
– Tuberculin test (PPD or Mantoux test)
= + (induration > 5 mm)
- X-ray
- Sputum – acid fast bacilli
Treatment – combination of INH, rifampicin, ethambutol, pyrazinamide
Carriers – human, animal
Prevention – BCG (Bacillus Calmette Guerin)- attenuated vaccine (live, weakened)
High risk – exposure to TB; elderly; illicit drugs; HIV + status; homeless people
What is the gold standard in diagnosis of TB?

12. Mycobacterium leprae Hansen’s disease
Grow best at 30˚C (peripheral nerve endings; skin cells in ear lobes, lips, fingers, toes)
Human and Armadillos hosts
Transmission – direct contact; inhalation of droplets; breaks in skin (only after years of intimate social contact)
2 forms – tuberculoid and lepromatous
Tuberculoid leprosy – nonprogressive destruction of body; loss of sensory in affected nerve (pain, temp., proprioception)

13. Lepromatous leprosy Virulent form
1990, 12 million cases worldwide; 2004, decreased to 457,792
(only 81 cases in US)
Incubation take years before S/Sx
Progressive disfigurement
Dx - + skin test with leprosy antigen
or direct AFB smear
Rx – multiple drug (clofazidime, rifampicin, dapsone for atleast 2 yrs. or lifelong for some)
Prevention – BCG; prophylactic antibiotics

14. Exotoxin Produced by both gram + and gram – bacteria
Released from cell
Protein chemical unit
Heat labile
Specific receptors on target cells
Specific effects in host
Toxoids (Antibodies) can be made by treating with formalin

15. Homework
Define terms – tuberculin test, BCG, lepromatous leprosy, tuberculoid leprosy, gas gangrene, Elek test, primary tuberculosis
Describe the 3 clinical manifestations of anthrax diseases and its prevention.
Discuss pathogenicity (causative agent) and prevention of gas gangrene, food-borne botulism, and tetany.
What diagnostic test is confirmative of an active case of tuberculosis?