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GRAM POSITIVE BACILLI

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GRAM POSITIVE BACILLI Clinically important Gram positive bacilli Spore forming Bacillus Clostridium Non spore forming 1.Corynebacterium 2.Listeria 3.Lactobacillus ... – PowerPoint PPT presentation

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Title: GRAM POSITIVE BACILLI


1
GRAM POSITIVE BACILLI
2
Clinically important Gram positive bacilli
  • Spore forming
  • Bacillus
  • Clostridium
  • Non spore forming
  • 1.Corynebacterium
  • 2.Listeria
  • 3.Lactobacillus
  • Bacilli w/ branching filaments
  • 1.Actinomyces
  • 2.Nocardia

3
1.BACILLUS
  • Bacillus anthracis
  • Human pathogen
  • Isolation also considered to be clinically
    significant
  • Zoonosis
  • Bacillus cereus
  • Environmental organism
  • Contaminates food
  • Common cause of food poisoning
  • Bacillus stearothermophilus
  • Tolerates very high temperatures
  • Used for quality control of autoclaves

4
a.Bacillus anthracis
  • Large bacilli of 1-3 ?m
  • Historical importance
  • Single or paired in clinical isolates
  • In vitro prominent capsule
  • Highly resistant spores

5
Anthrax Pathogenesis and clinical presentations
Cutaneous anthrax About 20 mortality
Virulence factors Capsule (antiphagocytic) Toxi
n (oedema death)
Inhalation anthrax High mortality
Gastrointestinal anthrax High mortality
6
Anthrax - Epidemiology
7
Anthrax - Diagnosis
  • Specimen
  • Aspirate or swab from cutaneous lesion
  • Blood culture
  • Sputum
  • Laboratory investigation
  • Gram stain
  • Culture
  • Identification of isolate

8
Anthrax treatment and prevention
  • Penicillin
  • (Tetracycline /chloramphenicol)
  • Erythromycine,Clindamicine
  • Prevention
  • Vaccination of animal herds
  • Proper disposal of carcasses
  • Active immunisation with live attenuated bacilli

9
b.Bacillus cereus
  • Large, motile, saprophytic bacillus
  • Heat resistant spores
  • Pre formed heat and acid stable toxin (Emetic
    syndrome)
  • Heat labile enterotoxin (Diarrhoeal disease)
  • Lab diagnosis Demonstation of large number of
    bacilli in food

10
Bacillus cereus clinical presentation
Gastroenteritis
EMETIC FORM
DIARRHOEAL FORM
Incubation period gt 6 hours Diarrhoea Lasts
20-36 hours
Incubation period lt 6 hours Severe vomiting Lasts
8-10 hours
11
CLOSTRIDIUM(ANAROBES)
  • Anaerobic
  • Sporing
  • Gram positive
  • Diameter of the spore is larger than the cell
    resemble a spindle
  • Clostridium is derived from Kloster meaning
    spindle

12
  • Spores Pleomrhic (elongated, spindle)

Most are obligate anaerobes produce neuro histo
toxins
13
  • Saprophytes - Most
  • Some are opportunists - tetanus/gas gangrene/food
    poisoning
  • Cl. perfringens - commensal of the intestine
  • Cl. sporogenes - -do-
  • Can invade the intestine after the death

14
CLASSIFICATION BASED ON THE TYPE OF DISEASE
PRODUCED
  • A . Tetanus Cl. tetani - Present in soil
  • B. Gas gangrene
  • Established Cl. perfringens gut organism
  • Cl. septicum
  • Cl. novyi
  • - Less pathogenic Cl. histolyticum
  • Cl. fallax
  • - Doubtful Cl. bifermentans
  • Cl. sporogenes

15
  • C. Food poisoning
  • 1. Gastroenterritis - Cl perfringens Type A
  • 2. Botulism - Cl. botulinum/ Soil
  • 3. Pig-bel Cl. perfringens type C
  • D. Acute colitis - Cl. difficile / gut organism
  • (pseudomembranous colitis)
  • Commonest cause of nosocomial diarrhoea

16
GAS GANGRENE
17
  • Dead tissue, blood clots, foreign matter aerobic
    organisms
  • In an injury
  • DEVELOP ANAEROBIC CONDITION
  • (Exogenous infection) Germination of spores
  • Gas gangrene
  • oedema, necrosis, gas production,
  • toxaemia, myositis
  • Crepitus

18

C Perfringens C histolyticum C septicum C novyii
C Perfringens
Alpha toxin (lecithinase)
19
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22
TETANUS
  • Cause tetanus in both man and animals
  • disease which effect the nervous system
  • of the host.
  • Agricultural workers and gardeners and
  • are more prone because the spores are
  • present in the soil.
  • At birth under unhygienic conditions babys
  • can get tetanus neonatorum.

23
  • Soil/Intestine/Vagina
  • Drum stick appearance
  • Motile with peritrichous flagella
  • Obligatory anaerobes
  • Grow on Robertsons cooked medium

24
  • All types produce the same toxin
  • C. tetani 10 types based on the H antigens
  • (CP 5 types based on the type of toxins, alpha,
    beta, epsilon, iota).

25
  • Susceptibility -
  • Some strains can withstand boiling for
    3hrs/dry heat 1600C for 1hr. but all will destroy
    at 1210C/15 min.

26
  • COMMON FEATURES FOR BOTH CT AND CP
  • All CPs produce alpha toxin
  • All CTs produce same exotoxin plasmid mediated
  • However, CPs got enterotoxins.
  • Exotoxin of CT has got two components
  • .Tetanolysin both heat and O2 labile may act
    as a leucocidin
  • .Tetanospasmin heat labile, but O2 stable
    (Therefore, can you give an edvantage ? will not
    get destroyed in the blood).

27
  • Spores germinate -------toxin-----motor nerve
    endings--------along the motor neurones of the
    peripheral nerve to the anterior horn
    cells------local tetanus (in the proximity of the
    wound).
  • Ascending tetanus when toxins spreads upwards
    along the spinal cord towards C.N.S. Gives
    generalized spasms.
  • Descending tetanus when toxin is given IV ,
    spasms will appear in the muscles of the head,
    neck and spreads downwards.

28
  • Clinical symptoms
  • Early symptom is trismus (lock jaw) spasms of
    the masseter muscle
  • difficulty in opening of the mouth and
    masticating
  • rigidity spreads to muscles of the face, neck and
    truck
  • risus sardonicus contraction of the frontails
    and muscles at the angle of the mouth
  • back is usually slightly curved (Opisthonotus ?)
  • Insevere cases violent spasms will last for few
    seconds to 3-4 mins.
  • If convulsions appear soon after the initial
    symptoms, it is very serious.
  • The spasms gradually intensify and patient may
    die of
  • .exhaustion, b. asphyxia or aspiration peumonia
  • - If local tetanus after a wound at the neck, you
    might think of tuberculous meningitis (irritation
    and paralysis is common).
  • What happens
  • Toxin acts at the synaptic junction prevent the
    synthesis of acetylcholine. Thus, prevents
    synaptic transmission.

29
Toxins
  • Tetanolysin - heat and oxygen labile/lyse RBC/
  • Tetanospasmin - heat and oxygen stable/highly
    lethal (for mice 0.0000001 mg) dies within 1 - 2
    days
  • get easily neutralize with antitoxin

30
GABA GLYCINE
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32
Clostridial food poisonng
  • C. perfringens
  • Carriers for food poisoning strains
  • Survival of heat resistant spores in bulk meals
  • Sporulation in gut - Short IP and watery
    diarrhoea for 24-48 hours
  • Beta toxin production in C. prerfringens type C
    Necrotizing enteritis(Pig bell)

33
BOTULISM Sausage
8 toxins (A-G)
Food borne botulism (IP 1-2 days) Infant
botulism Wound botulism (IP gt 4 days)
Diagnosis Isolation of organism in
food/faeces Detection of toxin in faeces / serum
34
Produces Botulism World wide distribution Found
in soil and occasionally in animal feces Sporese
are highly heat resistant ,withstand 100C for
3-5 hrs. Heat resistance is reduced by acid pH or
high salt concentrations Toxin Released during
growth and autolysis of bacteria. It is found in
7 antigenic varieties.A-G The principle cause for
human disease A,B,E/F
35
A,B - Variety of foods E - Fish products C -
Limberneck in birds D - botulism in mammals Toxin
is neurotoxic protein Destroyed by heating at
100C for 20 mins. Action Block release of
Acetylecholine at synapses and NMJ causing
flaccid paralysis. Pathogenecity Illness is not
an infection. Botulism is an intoxication
resulting from the ingestion of food in which
C.botulinum has produced toxin.
36
PSEUDOMEMBRANOUS COLITIS
Virulence factors Enterotoxin (Toxin
A) Cytotoxin (Toxin B)
Management Discontinue antibiotics Ampi/Tetra/Cli
nda Oral metronidazole Oral vancomycin
Diagnosis Clinical suspicion Culture of
faeces Detection of toxin
37
CORYNEBACTERIA(AEROBES)
  • Causes localized inflammation (pseudomembrane,
    greyish white exudate ) and generalized toxaemia
  • Prevalent in babys after 3-6 months (thats why
    DPT is given at 3, 5, 7 months, boosters at 18
    months and at school entry), very high in young
    children

38
Morphology
  • Gram/ve/palisade/Chineseletter arrangement
  • Irregular swellings at one end -club shaped.
  • Corynebacteria tend to pleomorphism in
    microscopic
  • and colonial morphology.

39
  • On blood agar Small granular gray with
    irregular edges and may have small zones of
    hemolysis.
  • Grow aerobically on ordinary media

40
  • a. Corynebacterium diphtheriae
  • Normal flora of nasopharynx in about
    10
  • Diphtheria caused when infected by lysogenic
    bacteriophage
  • b. Diptheroids
  • Normal flora of skin
  • Usual contaminants of samples
  • Can cause disease in compromised host
  • C. ulcerans C. haemolyticum
  • C. jeikeium

41
  • Rare in developed countries/ third world
    countries
  • Nose, Nasopharynx, skin aerobic, facultatively
    anaerobic
  • Nasal carriers are very dangerous

42
  • Loeffler's serum slope Blood telurite agar (black
    colonies)
  • Morphological differences
  • Three biotypes
  • Gravis (severe)
  • Inter-medius (intermediate)
  • Mitis (mild)

43
  • Epidemiology
  • It is rare in developing countries, a disease of
    the third world countries. Still highly prevalent
    in the former Soviet Union.
  • Spread through droplets.

44
Types of Diphtheria
  • Faucial
  • Laryngeal
  • Nasal
  • Conjunctival
  • Vulvovaginal
  • Otitic
  • Cutaneous around the mouth and the nose

45
Effect of toxins
  • 1. Local
  • 2. General
  • Toxaemia and acts on the myocardium and on motor
    nerves and adrenals
  • Complications
  • a, pseudomembrane may extend to larynx and cause
    obstruction
  • b.myocarditis /Polyneuropathy
  • Degenerative changes in the liver adrenals,
    kidney's

46
  • Pathology
  • Toxin is absorbed in the mucus membrane and
    causes
  • destruction of epethelium and causes a
    superficial
  • inflammatory respons.
  • Necrotic epethelium becomes embeded in exuding
    fibrin and red and white cells, with bacteria-
  • Grayish pseudomembrane is formed over the
    tonsilas
  • and pharynx and larynx.

47
  • Removal of pseudomembrane - capillary damage and
  • bleeding..
  • Regional lymphadynopathy with marked edema of the
  • neck within the membrane bacilli produce toxin.
  • This results in distant toxic damage
    paranchymatous
  • degeneration fatty infiltration necrosis in
    heart
  • muscle liver kidney adrenals.

48
  • How to identify the immune persons
  • Shick test suitably diluted stabilized toxin
    intradermally, localized erythema (1-3cm) in 2-4
    days, means no or little antibodies

49
  • Diagnosis
  • Direct smear - Albert's stain
  • Culture - Loffler's serum slope/blood agar/blood
    telurite agar
  • Check the toxigenicity
  • Animal inoculation
  • Death within 96 hrs
  • Guinea pigs/rabbits

50
  • Elek's plate test
  • Filter paper with antitoxin
    Precipitation
  • Strain

51
  • Management
  • 1. Patients - isolation of the patient / bed
    rest/antibiotic treatment/antitoxins (horse
    serum)
  • Penicillin/erythromycin/teracycline/rifampicin/cl
    indamycin
  • 2. Contacts immunize if not (toxoid) adults
    should be shick tested or given low dose as
    immunization of immune adults can result in
    severe reaction.
  • prophylactic antibiotic erythromycin
  • swab nose and throats of contacts

52
  • 3. Community immunization

53
DIPHTHERIA
DIAGNOSIS Clinical suspicion Swab for
culture Toxin production
PREVENTION Immunization (toxoid)
TREATMENT Penicillin Anti-diphtheretic
serum Maintaining airway Supportive
54
4.Listeria monocytogenes
55
5.LACTOBACILLUS(ANEROBES)
Normal flora of female genital tract Obligaete
anaerobes Low virulence
56
ACTINOMYCETES(FACULTATIVELY ANAEROBES)
  • Fermentative gp Actinomyces, Arcanobacterium and
    Rothia
  • Oxidative gp Actinomadura (actinomycetoma),
    Nocardia (nocardiosis), Streptomyces and related
    species.

57
Actinomycosis
  • A. israelii the commonest
  • A .meyeri
  • A.naeslundii
  • A.odontolyticus
  • A. viscosus

58
6. Actinomyces israelii
  • Has branching filaments
  • Facultative anaerobes
  • Normal flora of oral cavity
  • Causes Actinomycosis characterised by multiple
    abscess and granuloma formation
  • Tissue destruction, fibrosis and sinus formation

59
ACTINOMYCOSIS
  • Mostly in cervico-facial region
  • Endogenous infection
  • Can get
  • Thoracic actinomycosis (aspiration)
  • Pelvic actinomycosis (IUCD)
  • Rarely haematogenous spread
  • Treatment
  • Surgical
  • Long term penicillin

60
Diagnosis
  • Specimens open biopsy, aspiration material
  • Sulphur granules (yellowish myecelial masses)
  • The discharge should mix with sterile saline in a
    universal bottle and allow to stand, particles
    will separate out.

61
  • Place between 2 slides
  • Crush and gram stain
  • Gram positive branching filaments

62
ACTINOMYCOSIS
63
7.Nocardia asteroides
  • Branched, strictly aerobic bacillus
  • Environmental saprophytes (exogenous infection)
  • Lightly acid-fast
  • Uncommon causes of opportunistic pulmonary
    disease
  • Causes primary post-traumatic or post-inoculation
    lung disease

64
Cutaneous nocardiasis
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