PHARMACEUTICAL MICROBIOLOGY -1I PHT 313 Dr. Rasheeda HamidAbdalla Assistant Professor E-mail rasheedahamed12@hotmail.com

Objectives Listeria Clostridia Escherichia coli klebsiella

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

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)

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

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

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

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

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

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

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

Classification of Clostridia by Endospore Location

Terminal spores of c.tetani

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

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

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

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

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

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

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

Characteristic rigidity of the body

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. 

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

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

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

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

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

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

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

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

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

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

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