Dr Hamed Al-Zoubi Ass. Prof. / Medical Microbiology

Transcription

1 Dr Hamed Al-Zoubi Ass. Prof. / Medical Microbiology

2 PSEUDOMONAS BRUCELLA LEGIONELLA CAMPYLOBACTER HELICOBACTER PYLORI (H.PYLORI)

3 Pseudomonas Pseudomonas aeruginosa, Burkholderia pseudomallei and Burkholderia cepacia Most are saprophytes found widely in aquatic environments Major cause of nosocomial infections Usually multidrug resistant

4 Oxidase positive aerobic gram negative bacteria Motile 1-2 flagella Pigmented colonies with cut grass or grape like smell blue pigment, pyocyanin, and the yellow green fluorescent pigment pyoverdin

5 Virulence: Exotoxin A (EF2), protease, LPS, pigments production Exopolysaccharide (Alginate like )which is responsible for the mucoid colonial phenotype

6 Infections: Community and hospital acquired Burns infections Exacerbation of Cystic fibrosis and lung diseases Diagnosis: Selective media containing acetamide Commercial kits PCR Treatment: Follow lab sensitivity

7 Brucella (Malta fever) Brucellae are highly infectious gram negative coccobacilli that cause a septicaemic illness, undulant fever. Most human disease is caused by Brucella melitensis, B. abortus or B. suis Typical zoonosis most commonly acquired from infected animals, or from infected meat or dairy products.

8 Brucella (Malta fever) Non motile LPS killed at a temperature of 60 C for 10 min sensitive to direct sunlight and moderately sensitive to acid

9 Infection: Incubation period is usually about days The organisms are intracellular parasites and subsequently localize in various parts of the reticulo- endothelial system with the formation of abscesses or granulomatous lesions, resulting in complications that may involve any part of the body Brucellosis can present as an acute or subacute pyrexial illness that may persist for months or develop into a focal infection that can involve almost any organ system

10 Diagnosis: Samples suspected to contain brucellae must be treated as high risk. Cultures must be handled under containment conditions appropriate to hazard group 3 pathogens. 1- Repeated blood culture (I.Cellular organism ), B.M.. Incubated for 6-8 weeks 2- Serology 3. PCR Treatment: streptomycin or gentamicin with tetracycline Co-trimoxazole and rifampicin can be used in childre

11 L. pneumophila Weak gram negative bacilli LPS, penicillinase, cytotoxins and hemolysins Incubation: 2-10 days Water droplets from Air conditions, towers.. Pneumonia known as legionnaires disease with hyponatremia, Less serious influenza-like illness called Pontiac fever

12 Diagnosis buffered charcoal yeastextract agar (BCYE), which contains iron plus cysteine as an essential growth factor (colonies have cut glass appearance under micropscope ) Antigen detection in urine Treatments: Macrolides Control: No vaccine but chlorinating and heating water

13 Campylobacter The main human pathogen is campylobacter jejuni (C. jejuni) Habitat: Guts of various animal species such as chickens, domestic animals and seagulls Pathogenesis: Enterocolitis, may penetrate beyond the mucosa

14 Small gram negative, curved or spiral rods (Figure/seagull appearance) Highly motile (darting, corkscrew like movement), with a flagellum at one or both ends Microaerophilic (5% O 2, 10-15% CO 2, 80% Nitrogen) Growth at 42 C for 2 days (25 C no growth, 37 C some growth, 42 C enhanced growth). Needs a special media (Skirrow s)

15 Campylobacter Clinically: Incubation period: 1-10 days Route of transmission: Eating contaminated poultry, other meat or drinking milk Faecal oral between humans can occur

16 Campylobacter / clinically Bloody diarrhoea with mucus (up to 20 stools a day > faecal incontinence) Abdominal pain is a prominent feature (mimicking appendicitis) Septicaemia with fever and rigors in severe cases Symptoms may last several days and relapses are common (usually self limiting) Guillain-Barre syndrome as a complication.

17 Campylobacter Diagnosis Hx & Ex Stool sample for culture on Skirrow s medium Treatment: Erythromycin in severe cases. Ciprofloxacin as an alternative but resistance is increasing

18 H. pylori H. pylori on gastric mucus-secreting epithelial cells From Dr. Marshall'sstomach biopsy taken 8 days after he drank a culture of H. pylori (1985) > stomach is not inhospitable

19 H. Pylori / Properties Gram negative, spiral, flagellated (motile) bacilli H. pylori tuft of 4-6 sheathed flagella attached at one pole

20 H. Pylori / Properties Slow growing, requires complex media, microaerophilic (requires carbon dioxide, some Oxygen and Nitrogen) Oxidase, catalase and urease positive Proliferates in mucus overlying gastric antral mucosa > non invasive

21 H. pylori Culture: On special medium containing vancomycin, polymyxin and trimethoprim (Skirrow s) At 37 C for 3-7 days in microaerophilic conditions. Epidemiology: Man (Not zoonotic) appears to be the sole reservoir and source of H. pylori. How infection is transmitted is unknown, but it is presumed to be by the oral-oral or, possibly, faecal-oral route. Infection rates are strongly related to poor living conditions and overcrowding during childhood.

22 H. Pylori / epidemiology cont d Nosocomial infection from inadequately disinfected endoscopes has also occurred Remarkably, H. pylori, colonizes roughly half of the world's Population

23 H. Pylori / Pathogenesis sheathed flagella lophotrichous > motile enables penetration into viscous environment (mucus) Adhesins: Hemagglutinins; Sialic acid binding adhesin Mucinase: Degrades gastric mucus; Localized tissue damage Urease converts urea (abundant in saliva and gastric juices) into bicarbonate (to CO 2 ) and ammonia Neutralize the local acid environment Localized tissue damage

24 H. Pylori / Pathogenesis vacuolating toxin (VacA) and cytotoxin (CagA) > Epithelial cell damage The vacuolating toxin has been associated with pore formation in host cell membranes, the loosening of the tight junctions between epithelial cells (thus affecting mucosal barrier permeability causing vacualation) Protection from phagocytosis & intracellular killing: Superoxide dismutase Catalase

25 H. pylori/ Clinically Symptomless Acute infection: Abdominal pain, vomiting and fever may exist but no disseminated stage Chronic active gastritis; Type B. Gastric (70%) and duodenal ulcers (more than 90%). non-ulcer dyspepsia gastric malignancies.

26 H. Pylori / Diagnosis Definitive tests for H. pylori infection depend on finding the Organism in specimens of gastric mucosa obtained by biopsy. (In practice, non-invasive tests are used for initial screening). 1- Non-invasive tests: 1. Urea breath test 2. Faecal antigen 3. PCR 4. Serology

27 H. Pylori / Diagnosis Urea breath test Detects bacterial urease activity in the stomach by measuring the output of carbon dioxide resulting from the splitting of urea into carbon dioxide and ammonia A capsule of urea labelled with carbon-14 or (13)is fed to the patient, and the emission of the isotope in carbon dioxide subsequently exhaled in the breath is measured Carbon-14 is radio-active so it is not used in children

28 H. Pylori / Diagnosis 2. Invasive tests (endoscopy guided biopsies): Ideally, patients for endoscopy should not have received antibiotics or proton pump inhibitors for 1 month before the test. For maximum sensitivity, duplicate specimens are taken: one for histopathology, the other for culture

29 Treatment Life style: Ttriple therapies: Have reported cure rates from 85-90%. Administerd for days. There is more than one regimen e.g: Lansoprazole, amoxicillin, and clarithromycin

30 The End