1. بنام خداوند جان وخرد

2. Anaerobic Bacteria Clostridia cont… C. perfringens, C
Anaerobic Bacteria Clostridia cont… C. perfringens, C. difficile Bacteroides, Porphyromonas
Dr Alvandi
94-95

3. نمونه سوالات علوم پايه

4. کداميک از کلستريديوم هاي زير مي تواند عامل اسهال ناشي از مصرف طولاني مدت آمپي سيلين باشد؟
الف- كلستريديوم ديفيسيل
ب- كلستريديوم پرفرينجنس
ج- كلستريديوم بوتولينوم
د- كلستريديوم تتاني
شهريور 88

5. در اسهال هاي مرتبط با مصرف آنتي بيوتيک، شايعترين باکتري کدام است؟
الف- كلستريديوم ديفيسيل
ب- سودوموناس ايروژينوزا
ج- يرسينيا انتروکوليتيکا
د- كلستريديوم پرفرينجنس
شهريور86

6. كداميك از باكتري هاي زير عامل سببي گانگرن گازي (ميونكروز) مي باشد؟
الف- كلستريديوم پرفرينژنز
ب- سودوموناس ايروژينوزا
ج- استافيلوكوكوس اورئوس
د- كورينه باكتريوم ديفتريه
اسفند 84

7. كداميك از باكتري هاي زير عامل سببي کولیت با غشای کاذب می گردد؟
الف- شیگلا دیسانتری
ب- سالمونلا تیفی
ج- کمپیلوباکتر فتوس
د- کلستریدیوم دیفیسیل
شهریور 81

8. Pathogenic Clostridia
Species
Human Disease
Frequency
C. difficile
Antibiotic-associated diarrhea,
pseudomembranous colitis
Common
C. perfringens
Soft tissue infections (i.e.,Cellulitis, suppurative
myositis, myonecrosis or gas gangrene), food
poisoning, enteritis necroticans, septicemia
C. botulinum
Botulism
Uncommon
C. tetani
Tetanus
C. butyricum
Rare
C. novyi
Gas gangrene

9. Clostridium perfringens
Is one of few nonmotile clostridia
Rapidly spreading growth on laboratory media
(resembling motile organisms)
hemolytic
Lethal toxins subdivide isolates into five types (A-E)

11. Clostridium perfringens
Type
Alpha(α)
Beta (β)
Epsilon (ε)
Iota (ι) A x B C D E

12. Lethal toxin; phospholipase C (lecithinase); hemolysin
Virulence Factors
Biologic Activity
α toxin
Lethal toxin; phospholipase C (lecithinase); hemolysin
β toxin
Lethal toxin; necrotizing activity
(Enteritis necroticans, pig-bel)
ε toxin
Lethal toxin; permease
ζ toxin
Lethal binary toxin; ADP ribosylating
δ toxin
Hemolysin
Θ toxin
Heat- and oxygen-labile hemolysin; cytolytic
κ toxin
Collagenase; gelatinase; necrotizing activity
λ toxin
Protease
μ toxin
Hyaluronidase
ν toxin
Deoxyribonuclease; hemolysin; necrotizing activity
Enterotoxin
Alters membrane permeability; by type A strains
Neuraminidase
Alters cell surface ganglioside receptors;

13. Epidemiology
Type A commonly inhabits intestinal tract of humans and animals
in soil and water contaminated with feces
Types B-E do not survive in soil
colonize intestinal tracts of animals and occasionally humans
Type A is responsible for most human infections
soft tissue infections, food poisoning, and primary septicemia
Type C is responsible for enteritis necroticans (Pigbel)

14. Clinical Diseases 1- Soft Tissue Infections 2- Food Poisoning
Cellulitis
Fasciitis or suppurative myositis
Myonecrosis or gas gangrene
2- Food Poisoning
3- Necrotizing Enteritis
4- Septicemia

15. Clinical Diseases 1- Soft Tissue Infections
Most isolates of C. perfringens
species from wound cultures
are insignificant
Organisms can also initiate cellulitis
with gas formation in soft tissue
Can progress to suppurative myositis
Characterized by
An accumulation of pus in muscle planes
Absent of muscle necrosis and systemic symptoms

16. Clinical Diseases Myonecrosis or gas gangrene
Generally develops within a week after clostridia are introduced
Intense pain, Shock
Extensive muscle necrosis
Renal failure, Death
Cellular lysis by clostridial toxins
Abundant rectangular, gram-positive rods
Absence of inflammatory cells
C. perfringens, and other species
(C. septicum, C. histalyticum, and C. novyi)

17. Clinical Diseases Clostridial food poisoning
A short incubation period (8 to 24 hours)
Abdominal cramps, watery diarrhea (no fever, nausea, or vomiting)
A clinical course lasting less than 24 hours
Ingestion of meat product
108 to 109 organisms of type A C. perfringens
Reheating of food to 74° C can destroy heat-labile enterotoxin

18. Clinical Diseases Necrotizing Enteritis
Rare, acute necrotizing process in jejunum
Abdominal pain, bloody diarrhea, shock, and peritonitis
Mortality is 50%
β-Toxin-producing C. perfringens type C
Septicemia
Isolation from bloods patients with significant infections (myonecrosis, necrotizing enteritis)

19. Diagnostic Laboratory Tests
Clinical presentation
Large gram-positive rods in specimen (wounds, pus, and tissue) spores are not regularly present.
chopped meat-glucose medium and thioglycolate medium
A clot torn by gas in 24 hours is suggestive of C perfringens.
Lecithinase activity is evaluated by precipitate formed around colonies on egg yolk media
Toxin production and neutralization by specific antitoxin. C perfringens

20. Blood agar plate with C. perfringens:
characteristic double zone of hemolysis alpha-toxin incomplete outer zone theta-toxin clear inner

21. Laboratory Diagnosis Food poisoning
recovery of more than 105 organisms per gram of food or more than 106 bacteria per gram of feces collected within 1 day of onset of disease

22. Treatment, Prevention, and Control
Surgical debridement and high-dose penicillin therapy
Mortality ranging from 40% to almost 100%
Antibiotic therapy for clostridial food poisoning is unnecessary, because this is a self-limiting disease
Symptomatic treatment for food poisoning

23. Clostridium difficile

24. Physiology and Structure
Anaerobic, gram positive rod
Produces toxins
Pseudomembranous colitis
High prevalence among hospital patients
Antibiotic associated

25. Pathogenesis and Immunity
Virulence Factor
Biologic Activity
Enterotoxin
(toxin A)
Produces chemotaxis; induces cytokine production with
hypersecretion of fluid; produces hemorrhagic necrosis
Cytotoxin
(toxin B)
Induces depolymerization of actin with loss of
cellular cytoskeleton
Adhesin factor
Mediates binding to human colonic cells
Hyaluronidase
Produces hydrolytic activity

26. Clinical Disease Antibiotics disrupt normal flora
Ampicillin, cephalosporins, fluoroquinolones and Clindamycine
Uncontrolled proliferation of C. difficile
Onset days after start of antibiotic
Asymptomatic Carriage
Antibiotic-associated diarrhea without colitis
Antibiotic-associated colitis without pseudomembrane
Formation Pseudomembranous colitis
Fulminant disease (toxic megacolon, ileus, perforation, sepsis)

27. Epidemiology Colonizes 5% of healthy individuals endogenous infection
exogenous source of infection: Fecal-oral

28. Clinical Disease

29. C. difficile Associated Disease (CDAD)

30. Laboratory Diagnosis Symptoms Diagnostic tests
Loose, watery stools, Fever
Crampy lower abdominal pain, anorexia
Diagnostic tests
Stool studies: Toxin, fecal leukocytes
Labs: leukocytosis with left shift, dehydration, acidosis
Endoscopy: pseudomembranes
Radiology: thickened colonic wall, megacolon

31. Laboratory Diagnosis
Isolation of organism in stool culture documents colonization but not disease.
Demonstration of enterotoxin or cytotoxin in a stool specimen
Immunoassays.
In vivo cytotoxicity assay using tissue culture cells and specific neutralizing antibodies for cytotoxin

32. Laboratory Diagnosis Diagnosis: Detection of toxins
Detection of organism
culture of feces for C. difficile (48-72 h)
immunoassay
Detection of toxins
tissue culture

33. The appearance of Clostridium difficile on
cycloserine-cefoxitin-fructos agar (CCFA): yellow, "ground-glass“ colonies and a yellowing of the medium around the colonies

34. Treatment, Prevention, and Control
Discontinuation of implicated antibiotic (e.g., ampicillin,
clindamycin, fluoroquinolones)
Specific therapy with metronidazole or vancomycin is necessary for the management of severe diarrhea or colitis.
Relapses may occur in as many as 20% to 30% of patients after completion of therapy.
It is difficult to prevent disease, because organism commonly exists in hospitals, particularly in areas adjacent to infected patients (e.g., beds, bathrooms).
Spores of C. difficile are difficult to eliminate unless thorough housekeeping measures are used. Thus organism can contaminate an environment for many months and can be a major source of nosocomial outbreaks of C. difficile disease.

35. Treatment, Prevention, and Control
Most important: Cessation of inciting antibiotic
Non-antibiotic management:
Correction of fluid and electrolyte losses
Avoid anti-peristaltic agents
Indications for antibiotic treatment:
1) Evidence of colitis
2) Persistent diarrhea despite cessation of abx
3) Need to continue abx to treat underlying infection
Metronidazole; Vancomycin

36. Other Clostridial Species
C. septicum is a particularly important pathogen because it is a cause of non-traumatic myonecrosis and often exists in patients with occult colon cancer, acute leukemia, or diabetes.
after initial presentation. C. sordellii is implicated in fatal toxic shock syndrome associated with natural childbirth or medically induced abortions.
C. tertium s commonly isolated in soil samples. It has primarily been associated with traumatic wound infections (e.g., war wounds, a fall producing a soil-contaminated wound)

37. Anaerobic Gram-Negative Bacteria
colonize the human upper respiratory, gastrointestinal and genitourinary tracts
Anaerobes are the predominant bacteria at each of these sites, outnumbering aerobic bacteria 10- to 1000-fold.
Bacteroides,
Fusobacterium,
Parabacteroides,
Porphyromonas,
Prevotella
Veillonella

41. Treatment
all members of the B. fragilis group, many Prevotella and Porphyromonas species, and some Fusobacterium isolates produce β-lactamases.
metronidazole
carbapenems (e.g., imipenem, meropenem),
β-lactam–β-lactamase inhibitors (e.g., piperacillin-tazobactam).

42. Questions???

43. Thanks for your attention