Microbiology\College of Pharmacy Prof. Dr. Alaa H. Al-Charrakh Bordetella pertussis •Gram-negative coccobacilli •Due to filamentous haemagglutinin : have tropism for bronchial epithelium Growth requirements •Strict aerobe •Enriched media containing blood, albumin & starch : Bordet-Gengou medium •Split pearls or mercury drops colonies EXOTOXINS & PATHOGENESIS 1. Pertussis Toxin •Stimulates adenylate cyclase like diphtheria & cholera •Inhibits lymphocytes to enter lymphoid tissues - striking lymphocytosis pertussis toxin causes a striking lymphocytosis in the blood of patients with pertussis. The toxin inhibits signal transduction by chemokine receptors, resulting in a failure of lymphocytes to enter lymphoid tissue such as the spleen and lymph nodes. Because the lymphocytes do not enter lymphoid tissue, there is an increase in their number in the blood. 2. Invasive Adenylate Cyclase •Taken up by phagocytic cells - inhibits their phagocytic activity 3. Tracheal cytotoxin •Damages ciliated cells of respiratory tract •The organism is non-invasive : no bacteremia Clinical features of whooping cough •Source of infection : patient with whooping cough •Mode of Transmission : droplet infection •Incubation period : 7-10 days STAGES 1. Catarrhal (1-2 weeks) •Fever, sneezing, rhinorrhoea •Highly communicable - large no. of organisms are present in nasopharyngeal secretions 2. Paroxysmal (2-4 weeks) •Paroxysmal cough with an inspiratory whoop •Vomiting •Exhausted child - difficult breathing 3. Convalescent (3-4 weeks) •Severity of symptoms fades. 1 Microbiology\College of Pharmacy Prof. Dr. Alaa H. Al-Charrakh Lab identification Specimen : •Nasopharyngeal swab •Culture plate placed in front of mouth when patient is coughing Culture •On Bordet-Gengou medium Immunofluorescence staining •for rapid diagnosis (Organism not found in blood) TREATMENT Supportive •Oxygen •Suction of mucous in infants Antibiotics : Erythomycin or ampicillin •Reduces no. of organisms in throat but little influence on course of disease PREVENTION Vaccination: Pertussis vaccine incorporated with Diphtheria & Tetanus (DPT) •Given in first year of life Legionella pneumophila •Named after the famous outbreak of pneumonia among people attending the American Legion Convention in Philadelphia in 1976 •Gram-negative bacilli •Requires high conc. of iron & cysteine for growth Pathogenesis & Epidemiology •Associated with environmental water sources like: oACs & water cooling towers oWater taps, sinks & showers •Route of entry : respiratory tract •Persons at high risk oHeavy smokers & alcoholics oImmunocompromised •Disease : Legionnaire Disease Legionnaire Disease Clinical Features •May be mild influenzalike OR •Atypical pneumonia oProminent cough oScanty & nonpurulent sputum oIn old & immunocompromised patients can be fatal Lab Diagnosis oCulture on enriched media with iron & cysteine 2 Microbiology\College of Pharmacy Prof. Dr. Alaa H. Al-Charrakh oDetection of increased antibody titre Treatment & Prevention oErythromycin oHyperchlorination of hospital water supplies Brucella • Gram-negative bacilli Habitat • Chronically infected domestic animals Medically Important Species • B. abortus - Cattles • B. melitensis - Goats & sheep B. suis - pigs • B. canis - Dogs Transmission • Primarily animal disease: B. abortus causes abortion (in pregnant animals but not in pregnant women) & sterility of male animals due to presence of erythritol in animal reproductive tissue and placenta of pregnant cattles,which considered as a growth factor for this organism. causes abortion & sterility Transmission • From animals to animals & humans by: ° Abrasion in skin ° Inhalation ° Ingestion of contaminated milk & cheese • Persons at High Risk ° Dairy workers & farmers ° Live stock handlers & veternarians ° Slaughterhouse employees CLINICAL FEATURES OF BRUCELLOSIS (Undulating fever) • Incubation period: 1-3 weeks • Initially influenza-like • Undulating (rising & falling) fever for weeks & months 3 Microbiology\College of Pharmacy Prof. Dr. Alaa H. Al-Charrakh PATHOGENESIS OF B RUCELLOSIS (Undulating fever) Invasion through Recurrent skin & mucus chills & fver membranes Intermittent release LN, liver, spleen of bacilli from & bone marrow granuloma Formation of Survive & multiply abscesses, granuloma within macrophages & caseation • Infection of mammary glands of both animals& humans occur. Bacilli shed in milk • Placental transfer & fetal infection occurs only in animals due to presence of erythritol in placental tissues 4 .