An anaerobe is an organism that does not require oxygen for growth. The document discusses various Clostridium species that are anaerobic bacteria. Clostridium perfringens can cause gas gangrene through secretion of exotoxins and enzymes. It is also a common cause of food poisoning. Clostridium botulinum produces a neurotoxin that causes botulism. Clostridium tetani secretes a toxin that causes the muscles spasms seen in tetanus. Clostridium difficile is associated with antibiotic-associated diarrhea and pseudomembranous colitis.

1. 

2. Presented by
DR KHALID YOUSUF MEMON
LECTURER
LIAQUAT UNIVERSITY OF MEDICAL &
HEALTH SCIENCES JAMSHORO

3. 
 An anaerobic organism or anaerobe is any organism
that does not require oxygen for growth. It may react
negatively or even die if oxygen is present.
DEFINATION

4. 
classification

5. 
classification

6. 
classification

7. 

8.  Oxygen (O2)
Dr.T.V.Rao MD 8
The Requirements for Growth:
Related to Oxygen
Table 6.1

9. 
 C. PERFRINGENS: gas gangrene; food poisoning
 C. TETANI: tetanus
 C. BOTULINUM: botulism
 C. DIFFICILE: pseudomembranous colitis
Clostridium

10. 
 Large gram-positive rods.
 Anaerobic.
 Spore Forming: Rackit shape
 Most clostridia are motile by flagella.
 Mostly Non Capsulated
GENERAL FEATURES

11. 

12. 
 Clostridia, part of the intestinal flora They are found in
 SOIL,
 SEWAGE
 when introduced into tissues (for example, by a break in
the skin resulting from surgery or trauma).
 Endospore formation facilitates their persistence in the
environment.
 Spores are resistant to chemical disinfectants and may
withstand ultraviolet irradiation or boiling temperatures
for some time, although not standard autoclaving
conditions (121°C for 15 minutes at increased pressure).

13. 
 C. perfringens is a large, non-motile, gram-positive,
encapsulated bacillus.
 It is ubiquitous in nature
 Its vegetative form as part of the normal flora of the
vagina and gastrointestinal (GI) tract.
 Its spores are found in soil
Clostridium perfringens

14. 
 Can cause
 ANAEROBIC CELLULITIS
 MYONECROSIS (gas gangrene)
 FOOD POISONING Some strains of C. perfringens
can cause food poisoning
C. perfringens

15. 
 C. perfringens secretes a variety of
 EXOTOXINS,
 ENTEROTOXINS
 HYDROLYTIC ENZYMES (that facilitate the disease
process )
Pathogenesis:

16. 
 C. perfringens elaborates at least 12 exotoxins,
designated by Greek letters.
 The most important of these
 α TOXIN ( lesithenase C )
 PERFRINGOLYSIN O,
 THETA(Θ) TOXIN,
EXOTOXINS

17. 

18. 
 .C. perfringens strains are grouped A to E on the
basis of their spectrum of exotoxins.
 TYPE A STRAINS, which produce both α toxin and
enterotoxin, are responsible for most human
clostridial infections.
STRAINS

19. 
 C. PERFRINGENS ENTEROTOXIN, a small, heat-
labile protein, acts in the lower portion of the small
intestine. The molecule binds to receptors on the
epithelial cell surface and alters the cell membrane,
disrupting ion transport (primarily in the ileum) and
leading to loss of fluid and intracellular proteins.
Interestingly, enterotoxin- They are heat resistant,
the spores remaining viable for longer than an hour
at 100oC, enhancing their threat as foodborne
pathogens.
Enterotoxin:

20. 

21.  PROTEASES,
 DNASES,
 HYALURONIDASE,
 COLLAGENASES,
 These liquefy tissue and promote the spread of
infection. The resulting degradation products serve
as fermentation substrates for the rapid metabolism
of C. perfringens.
 This organism has one of the fastest doubling times
recorded, at less than 10 minutes
Degradative enzymes:

22. 

23. 
Clostridial spores are introduced into tissue, for
example, by
Contamination with infected soil,
Endogenous transfer from the intestinal tract.
 Severe and open wounds, such as compound
fractures
 Ischemia producing injuries (for example, crush
injuries), are a prime predisposing condition
1.MYONECROSIS (GAS GANGRENE)

24. 
GAS GANGRENE

25. 
 α Toxin and other exotoxins are secreted, and
extensive cell death ensues. Production of enzymes
that break down extracellular matrix facilitates the
spread of infection. Fermentation of tissue
carbohydrates, lipids, and amino acids yields gas,
and an accumulation of gas bubbles in the
subcutaneous spaces produces a crinkling sensation
on palpation (crepitation), hence, the name “gas
gangrene”
pathogenesis

26. 
 The exudates are copious and foul smelling. Leads
in systemic effects, such as shock, renal failure, and
intravascular hemolysis.
 Untreated clostridial myonecrosis is uniformly fatal
within days of the initiation of gangrene
presentation

27. 
 This is a clostridial infection of connective tissue in
which the spread of bacterial growth along fascial
planes (fasciitis) does not involve invasion of muscle
tissue.
 Necrotizing processes play a more limited role, but
surgical intervention is generally unsuccessful
(unless it is carried out very promptly and
aggressively) because of the rapid spread of infection
and compromise of blood supply due to swelling
beneath tight fascia.
2.Anaerobic cellulitis:

28. 
 C. perfringens is a common cause of foodborne infection
in the United States. Meats, meat products, and gravy are
the most commonly implicated foods in C. perfringens
foodborne illness.
 Typically, the onset of
 NAUSEA,
 ABDOMINAL CRAMPS,
 AND DIARRHEA occurs 8 to 18 hours after eating
contaminated food. Fever is absent and vomiting rare.
The attack is usually self-limited, with recovery within 1
to 2 days.
Foodborne infection

29. 
 Outbreaks of a necrotizing bowel disease with high
mortality (greater than 50 percent) caused by C.
perfringens have been sporadically reported.
Necrotic enteritis

30. 
 This condition is a grave complication of incomplete
abortion or the use of inadequately sterilized
instruments. Gangrenous infection of uterine tissue
is followed by illness due to toxins and bacteremia.
Clostridial endometritis

31. 
 Diagnosis of clostridial myonecrosis or cellulitis rests
largely on clinical presentation.
 GRAM STAIN, however, specimens from diseased
tissue usually show vegetative clostridial forms
(large,gram-positive rods), accompanied by other
bacteria and cellular debris.
 CULTURED ANAEROBICALLY on
 blood agar,(double hemolysis) alpha toxin and
perfringolysin O
 Lactose egg yolk medium
Laboratory identification:

32. 
 C perfringens produce an opacity in medium egg
yolk agar containing lecithin due to lecithenase c
activity (alpha toxin). This opacity is inhibited by
applying specific anti toxic serum to medium which
will inactivate lecithenase this technique is referred
as Nagler reaction
Nagler reaction

33. 
BLOOD AGAR

34.  IMMEDIATE AND THOROUGH REMOVAL OF
FOREIGN MATERIAL and devitalized tissue and
exposure of the wound toO2.
 HYPERBARIC OXYGEN CHAMBERS increase the
tissue O2 tension in the affected part and inhibit the
pathologic process.
 If DEBRIDEMENT is unable to control the
progression of the gangrene,
 AMPUTATION, when anatomically possible, is
mandatory in gangrene.
 ADMINISTRATION OF ANTIBIOTICS
 Penicillin
Treatment and prevention:

35. 
 C. botulinum causes botulism, which occurs in
several clinical forms.
 Botulism is caused by the action of a neurotoxin that
is one of the most potent poisons known and causes
a flaccid paralysis. due to ingestion of toxin-
contaminated food.
CLOSTRIDIUM BOTULINUM

36. 
 C. botulinum is found worldwide in soil and aquatic
sediments, and the spores frequently contaminate
vegetables and meat or fish.
 Under appropriate conditions,, outbreaks frequently
occur in families or other eating groups
Epidemiology:

37. 
 Types of botulinum toxin, A through G,
 In human disease is almost always caused by types A, B,
or E.
 Cause neurotoxicity arises from proteolytic cleavage of
specific synaptic vesicle peptides, causing subsequent
failure of neurotransmission.
 Botulinum toxins affect peripheral cholinergic synapses
by blocking the neuromuscular junction and inhibiting
release of the neurotransmitter acetylcholine, preventing
contraction and causing flaccid paralysis (B).
Pathogenesis:

38. 
pathogenesis

39. 
 Food poisoning in which a patient first begins to
experience difficulties in
 FOCUSING VISION (12 to 36 hours).
 A progressive paralysis of striated muscle groups
develops, and mortality rate is about 15 percent, with
the patient usually succumbing to respiratory
paralysis. Recovery, which involves regeneration of
the damaged nerves, is protracted, lasting several
weeks.
. Classic botulism

40. 
 Supplementation of infant foods (cereals or formula)
with raw honey, which is contaminated with C.
botulinum spores, may transmit the organism. The
condition is possibly a cause of sudden infant death
syndrome, but recovery is the usual outcome,
Following symptomatic treatment that may be
prolonged.
Infant botulism

41. 
 A rare form of botulism occurs when a wound
becomes contaminated with the organism, and toxin
is absorbed from that site. The molecular
pathogenesis of this infection is similar to that of
tetanus.
Wound botulism:

42. 
 The organism can be cultured and identified by
standard anaerobic methods . Toxin is also
identifiable in serum, stool, and food.
Laboratory identification:

43. 
 Antitoxin, which neutralizes unbound botulinum
toxin, should be administered as soon as possible in
suspected botulinal intoxication.
 A trivalent (A, B, E) horse antiserum is available
from the Centers for Disease Control.
 Supportive measures, including mechanical
ventilation, may be required. In wound and infant
botulism, the infection can be treated with penicillin
or other antibiotics to which the organism is
sensitive.
Treatment and prevention

44. 
 The introduction of C. tetani spores into even small
wounds via contaminated soil.
 Growth of C. tetani is completely local, but it
produces a powerful neurotoxin that is transported
to the central nervous system, where it causes spastic
paralysis.
D. Clostridium tetani

45. 
 : C. tetani spores are common in barnyard,
garden,and other soils.
 The most typical focus of infection in tetanus is a
puncture wound caused which tetanus spores can
germinate and grow.
 Special circumstances may also lead to tetanus, for
example, after severe burns, surgery or ischemia.
Illicit drugs can contain spores that are introduced
by injection
Epidemiology

46. 
 Tetanus toxin, called tetanospasmin, is an extremely
potent toxin. It is transported from an infected locus
by retrograde neuronal flow or blood.
 (A, or activity subunit) The A subunit blocks
neurotransmitter release at inhibitory synapses, there
by causing severe, prolonged muscle spasm small
synaptic vesicle protein (synaptobrevin) and
abolishing the flow of inhibitory neurotransmitters,
including glycine and γ-aminobutyric acid.
Pathogenesis:

47. 

48. 
 INCUBATION PERIOD---- 4 DAYS TO WEEKS
 Tetanus presents as a spastic paralysis, in which muscle
spasms often first involve the site of infection.
 In the early stages of the disease, the jaw muscles are
affected, so that the mouth cannot open (trismus, or
“lockjaw”).
 Gradually, other voluntary muscles become involved and
any external stimulus (for example, noise or bright light)
precipitates a painful spasm and, sometimes, convulsions.
 Death, which occurs in 50 to 60 percent of cases, is
usually the result of paralysis of chest muscles leading to
respiratory failure
Tetanus

49. 
Tetanus.

50. 
OPISTHOTONOS

51. Tetanus.

52. 
Risus sardonicus (LOCK JAW)

53. 
NEONATAL TETNUS

54. 
 The diagnosis of tetanus is based largely on clinical
 findings.
 C. tetani has a characteristic morphology, with a
long, slender rod and round, terminal spore (racket-
shaped bacillus),
 swarming growth on anaerobic blood agar.
Laboratory identification:

55. 

56. 
 ADMINISTRATION OF ANTITOXIN to neutralize any
toxin not yet bound to neurons is the first order of
treatment.
 HUMAN HYPERIMMUNE GLOBULIN (tetanus
immune globulin) is preferred, but, in countries where it
is not available, horse antitoxin is used.
 ANTIBIOTICS The organism is sensitive to penicillin,
 DEBRIDEMENT OF NECROTIC TISSUE at the entry
wound.
 SEDATIVES AND MUSCLE RELAXANTS to minimize
spasms and attention to maintenance of ventilation
Treatment:

57. 
 ACTIVE IMMUNIZATION WITH TETANUS TOXOID
(formalin inactivated toxin) prevents tetanus. It is usually
administered to children as a triple vaccine with diphtheria
toxoid and pertussis antigens (DTP).
 Recent studies have confirmed that circulating antibody levels
gradually decline and that many older individuals lose
protection. Therefore, booster immunizations with a
preparation of diphtheria and tetanus toxoids given every 10
years throughout life are recommended.
 TETANUS IMMUNOGLOBULIN can be used to give
immediate passive immunity to injury victims with no history
of immunization. Active immunization should also be started.
Antitoxin and toxoid, administered in different areas of the
body, can be given simultaneously
Prevention

58. 
 Diarrhea, a common complication of antimicrobial
drug treatment, can range from loose stools to life-
threatening pseudomembranous colitis (PMC)
 C. difficile is estimated to be responsible for at least
one fourth of antibiotic-associated diarrheas
E. Clostridium difficile

59. 
 In hospitalized patients and almost all cases of PMC.
After its introduction to a site, the environment (that
is, dust, bedding, toilets, etc.) becomes persistently
contaminated with spores, and new residents are
easily colonized. They are then at higher risk for
developing the adverse intestinal effect of antibiotic
treatments.

60. 
 C. difficile is a minor component of the normal flora of
the large intestine.
 When antimicrobial treatment suppresses more
predominant species in this community,
 C. difficile proliferates Pathogenic strains produce two
toxic polypeptides, designated toxins A and B.
 Toxin A is an enterotoxin that causes excessive fluid
secretion, but also stimulates an inflammatory response,
and has some cytopathic effect in tissue culture.
 Toxin B is a cytotoxin. In tissue culture, it disrupts
protein synthesis and causes disorganization of the
cytoskeleton.
1. Pathogenesis

61. 
 The three drugs most commonly implicated are
 CLINDAMYCIN,
 AMPICILLIN
 CEPHALOSPORINS.
 The pseudo membranous exudate, composed of mucus,
fibrin, nflammatory cells, and cell debris overlying an
ulcerated epithelium, is best demonstrated by endoscopy.
 PMC often begins some time after cessation of drug
treatment or may recur after what should be adequate
therapy. This is a consequence of the stability and
persistence of the spores formed by C. difficile
Clinical significance:

62. 
 CULTURED FROM STOOLS and identified by
routine anaerobic procedures, but the more rapid
and useful tests are directed at demonstrating toxin
production in stool extracts.
 ENZYME IMMUNOASSAYS (ELISA, for exotoxins
 A and B have replaced earlier immunologic or tissue
culture cytotoxicity assays.
 POLYMERASE CHAIN REACTION (PCR)–based
detection strategies are also widely available.
3. Laboratory identification

63. 
 : Discontinuance of the predisposing drug and fluid
replacement usually lead to resolution of the
symptoms.
 Relapses, however, are common. Oral
administration of metronidazole or vancomycin is
usually added Reconstitution of the host's normal
colonic flora may aid in the recover
Treatment

64. 
 Members of the genus Bacteroides are the predominant
anaerobes found in the human colon. They are part of the
normal flora and only cause disease when they gain access to
tissues or the blood during bowel penetration (for example,
during surgery or trauma).
 They are, however, the most common cause of serious
infections by anaerobic organisms.
 Bacteroides are slender rods or cocco - bacilli.
 Their polysaccharide capsule is an important virulence factor ,
conveying resistance to phagocytosis.
 Purified capsule alone is sufficient to induce abscess formation
in laboratory animals, indicating that this polysaccharide is key
to the pathology seen with Bacteroides infections.
A. Bacteroides

65. 
 Bacteroides are transmitted from the colon to the
blood or peritoneum following abdominal trauma.
Therefore, the source of infection is endogenous (it is
not transmitted from person to person
Epidemiology:

66. 
 The major disease-causing Bacteroides species is
Bacteroides fragilis.
 When released from the colon into the blood, B.
fragilis multiplies rapidly, causing bacteremia.
 If it is introduced into the abdominal cavity, B.
fragilis causes peritonitis, and/or abdominal
abscesse
Pathology and clinical
significance:

67. 
 : Exudates from mixed anaerobic lesions are often
copious and noticeably foul smelling.
 A Gram stain of such exudates shows numerous
faint, slender, gram-negative rods, usually in mixed
flora. The organisms are easily obscured by debris
and polymorphonuclear leukocytes.
Laboratory identification

68. 
 Drug resistance is common among the Bacteroides.
Metronidazole is the antibiotic of choice for B. fragilis
infections.
 Alternative choices include
 Ampicillin-Sulbactam, Imipenem-Cilastatin,
Ticarcillin-clavulanate, Cefoxitin, or Clindamycin.
 Surgical drainage of any abscess is essential to ensure
penetration of drugs. To prevent Bacteroides
contamination of a surgical wound,
 Perioperative antibiotic, such as cefoxitin, can be
administered.
Treatment and prevention: