1. PHARMACEUTICAL MICROBIOLOGY -1I PHT 313
Dr. Rasheeda HamidAbdalla
Assistant Professor

2. Objectives
Listeria
Clostridia
Escherichia coli
klebsiella

3. Listeria monocytogenes
Slender , short ,gram-positive rods, do not form spore
Avid intracellular parasites
Some times occur as diplobacilli or in short chains
Catalase positive
Display distinctive tumbling motility in liquid medium
Most active after growth at 25oC

5. Epidemiology Infect animals Human exposure is limited
usually food borne
Generally processed dairy products ( ice cream and cheese) because it grows at low temperature (4 OC)
meats also can contain Listeria
1-15% of healthy humans are asymptomatic intestinal carriers
Listeria most common in pregnant women ,their fetuses or newborns
Elderly or AIDS patients (immunocompromised)

7. Listeriosis Clinical Infections
Adults
Septicemia and meningitis are the most commonly reported forms of L.monocytogenes infection (Listeriosis).
Lymphadenitis and Endocarditis May also occur
Mild “flu-like “ illness in pregnant women could be fatal to fetus
Premature labor, spontaneous abortion
_Immuno-compromise individual are susceptible to generalized infections

8. Laboratory Diagnosis: L. monocytogenes
Identification
Microscopic morphology
Gram-positive
non-spore-forming
coccobacillary

9. Laboratory Diagnosis: L. monocytogenes (Cont’d)
The organism can be isolated from blood or CSF
Cultural characteristics
Grows well on blood agar
Colonies produce a narrow zone of hemolysis
Similar to group B Streptococcus
-distinguished from various streptococci by morphology ,positive motility , and the production of catalase

11. Treatment and Prevention
Variety of antibiotics used successfully to treat L.monocytogenes including:
Ampicillin ,trimethoprim-sulfamethoxazole
Prevention
by proper food preparation and handling .

12. Clostridia Clostridia are the anaerobic gram positive rods
Clinically significant species of Clostridia include:
C. perfringens
Causes:
histotoxic (tissue destructive) infections (Myonecrosis)
Anaerobic cellulitis
Food poisoning

13. Clostridia C. tetani Causes tetanus (lockjaw) C. botulinum
C. difficile
Causes pseudomembranous colitis associated with antibiotic use
C. tetani
Causes tetanus (lockjaw)
C. botulinum
Causes botulism

14. Gram-Positive Spore Forming Anaerobic Bacilli
All in the genus Clostridium
Gram-positive spore-forming rods
Spores position useful in identifying the species
Most species are motile
Obligate anaerobes
Synthesize some of most potent exotoxin
The toxins of specific Clostridial species cause:
Botulism ,tetanus , gas gangrene, and pseudomembranous colitis

15. Classification of Clostridia by Endospore Location

16. Terminal spores of c.tetani

17. Clostridium perferinges
Causes:-
Myonecrosis or gas gangrene
Anaerobic cellulitis
Food poisoning
Ingestion of enterotoxin causing diarrhea and cramps
Usually self-resolving
Clostridial Endometritis
Enteritis necroticans

18. Pathogenesis of Clostridium perferinges
Secretes a variety of
Exotoxins
At least 12 exotoxins
Alpha toxin is the most important causing lysis of endothelial cells ,erythrocytes , leukocytes, and platelets
Enterotoxins
Leading to loss of fluid and intracellular proteins
Degradative enzymes
liquefy tissue and promote the spread of infection

19. Clostridium perfringens
Myonecrosis (gas gangrene )
Clostridial spores are introduced into tissue for example by
-Contamination with dirt
-Endogenous transfer from intestinal tract
Causes by several species
The deadly form of gangrene usually is caused by Clostridium perfringens  bacteria

21. Myonecrosis (Cont’d) The organism grow, multiply and produce toxin
Alpha toxin causes tissue necrosis and deeper invasion
Causes death of tissue that can require amputation
Symptoms
Pain and swelling with obvious tissue necrosis

22. Treatment Antibiotic and surgical debridement of necrotic tissue
Exposure of wound to oxygen
Hyperbaric oxygen can help destroy anaerobes
Amputation ,when anatomically possible is still mandatory in uncontrollable gangrene

23. Tetanus Causative agent
Clostridium tetani
Infection by Introduction of C.tetani spores into even small wounds via contaminated dirt is probably a common occurrence
Pathogenesis
Tetanus toxin called tetanospasmin is extremely potent toxin
The mature toxin of two fragments( A) and (B)
B fragment mediate binding to neurons and cell penetration of fragment A
A fragment blocks neurotransmitter release at inhibitory synapse , thus causes severe prolonged muscle spasms

24. Clinical significance
Incubation period varying from 4days-several weeks
Muscular rigidity of the jaw (lock jaw), neck, and lumbar region
Difficulty in swallowing
Sometimes involves limbs as well

25. Characteristic rigidity of the body

26. Treatment and prevention
Prompt administration of antitoxin is first order of treatment
Vigorous treatment with sedatives and muscle relaxants
The organism sensitive to penicillin
Prevention:
DPT vaccine (Triple vaccine)
-a class of combination vaccines against three infectious diseases in humans: diphtheria, pertussis (whooping cough), and tetanus. 

27. Botulism Clostridium botulinum
Causes botulism, which occur in several clinical forms
Sources of infection
- spores frequently contaminate vegetables and meat or fish
Botulism is caused by the action of neurotoxin
The botulinum neuron toxin is extremely potent
Inhibit the release of neurotransmitter acetylcholine
Causes flaccid paralysis
In contrast to tetanus
The disease can be a pure intoxication

28. Clinical significance
a-Classic botulism is a food poisoning in which a patient first begins to experience difficulties in focusing vision , swallowing , and other cranial nerve functions
b-Infant botulism
Ingestion of spores in contaminated honey
Colonize the colon and produce toxins
C-wound botulism

29. C. difficile Causes : Antibiotic-Associated Diarrhea
Most common isolate in antibiotic-associated diarrhea (AAD)
Can cause pseudomembranous colitis(PMC) in hospitalized patients
Necrosis of colon tissue and bloody diarrhea
Small numbers of C.difficile part of the normal flora of the large intestine , when antibiotics suppresses more predominant of these species C.difficile start proliferates
Increased growth causing toxin production
Toxin A - Enterotoxin
Toxin B - Cytotoxin

30. Antibiotic-Associated Diarrhea (Cont’d)
Commonly transmitted as a nosocomial infection
Hands of hospital personnel
Most places will not culture for this pathogen
Test for toxin production

31. Enteric Gram Negative Rods
All of these organisms found in the gastrointestinal tract of humans or other animals
Also found on soil or water
True facultative anaerobes
They contain lipoplysaccharide (LPS)
Fecal contamination is frequently is important in transmission of these organisms that cause gastrointestinal diseases

33. Escherichia coli Genus of the family enterobacteriaceae which include:
Salmonella ,Shigella , Enterobacter , Klebsiella ,Serratia and Proteous
E.coli is part of the normal flora of colon in humans and other animals
Can be pathogenic both within and outside of the gastrointestinal tract
Has fimbriae or pili
Different strain me be motile or nonmotile
Most strains can ferment lactose (Lac+ )
Produces acid and gas during fermentation of carbohydrates

34. Structure and physiology
E.coli shares many properties with the other Enterobacteriaceae
They are all:
True facultative anaerobes
Ferment glucose
Generate energy by reducing nitrate to nitrite
Lack cytochrome oxidase (oxidase negative)
Typing of strains is based on differences in three structural antigens:
- O ,H , and k
specific serotypes are associated with particular diseases .e.g . E. coli possessing O157 and 7H (O157:7H) causes severe form of hemorrhagic colitis

35. Clinical significance intestinal disease
1- Enterotoxigenic E.coli (ETEC)
-are common cause of traveler’s diarrhea
2-Enteropathogenic E.coli (EPEC)
-Important cause of infant diarrhea
3-Enterohemorrhagic E.coli (EHEC)
-Causing hemorrhagic colitis
4- Other E.coli infections :
Enteroinvasive E.coli (EIEC)
-Causes dysentery –like syndrome
Enteroadherent E.coli (EAEC) also causes traveler’s diarrhea

36. Clinical significance Extra-intestinal disease
The source of infection for extra-intestinal disease frequently the patient’s own flora
1- Urinary tract infections (UTI)
E.Coli the most common cause of UTI ,including cystitis and pyelonephritis
2-Neonatal meningitis
3-Nosocomial (hospital –acquired)infection

37. klebsiella Klebsiella K. pneumoniae and K.oxytoca
Nonmotile bacilli
Possess luxurious capsule
Lac+
K. pneumoniae and K.oxytoca
Cause a necrotizing lobar pneumonia in individual compromised by alcoholism , diabetes or chronic obstructive pulmonary disease
K. pneumoniae also causes UTI and bacteremia ,particularly in hospitalized patients
Moist grey mucoid colonies
Virulence factor
Polysaccharide capsule
Prevents phagocytosis and some antimicrobials

38. THANKS