Acinetobacter - Microbiology Presentation PDF

ACINETOBACTER ACINETOBACTER GENERAL CHARACTERISTICS Gram negative Coccobacilli Strict aerobe Non-motile (no flagella) Catalase positive Oxidase negative (majority) or positive  ACINETOBACTER 10 species already identified Two most common in clinical specimens : A. baum...

ACINETOBACTER ACINETOBACTER GENERAL CHARACTERISTICS Gram negative Coccobacilli Strict aerobe Non-motile (no flagella) Catalase positive Oxidase negative (majority) or positive  ACINETOBACTER 10 species already identified Two most common in clinical specimens : A. baumannii A. iwoffii 2nd most frequent NFGNB encountered in clinical laboratories Isolation rate about one tenth of P. aeruginosa. Cause opportunistic infections characteristically Account for 1-3% of all nosocomial infections  EPIDEMIOLOGY In hospitals Extensive spread in already Environmental reservoir colonized & hospitalized Soil Environmental surfaces Fresh water Ventilators & ventilation systems Vegetables Dialysis machines Animals Water sources Body of lice, Fleas, Ticks Hands, Wounds Inhabits the pharynx of about Respiratory, urinary & GIT tracts 25% of healthy adults disorders  PATHOGENESIS Opportunistic pathogen 2.Fimbriae/ Pilli : Survive under dry condition bronchial epithelium Virulence factors adherence 1.Polysaccharide capsule: surface colonization prevent complement biofilm formation activation delay phagocytosis TRANSMISSION Direct contact Indirect contact  A. BAUMANNII ASSOCIATED UTI DISEASES Pneumonia, Can colonize up to 45% of patents Tracheobronchitis with tracheotomy Endocarditis with up 25% Previously considered mortality contaminants or Meningitides Septicemia insignificant colonizer Truman infections, Now an important pathogen Burn infections, (resistance) Eye infections DIAGNOSIS Sample: depends on infection types Culture Identification Antibiotics susceptibility testing Molecular detection  CULTURE & COLONIAL MORPHOLOGY Aerobic Grows best at 44OC Differential medium : MacConkey Selective media: CHROME Agar Leeds Acinetobacter Agar CULTURE & COLONIAL MORPHOLOGY Colonial morphology on MacConkey agar good growth colonies not pigmented Penicillin resistant (traditionally= Penicillin susceptibility) Non-haemolytic MICROSCOPY & GRAM STAIN Direct Gram Tiny diplococci Gram negative Gram from Broth cultures larger & more like coccobacilli Gram negatives Non- motile  BIOCHEMICALS & OTHER IDENTIFICATION Catalase +ve Molecular detection ( A buamanni & A. iwofii)PCR Glucose, Xylose & Lactose recA gene: 382bp in A fermentation ( A buamanni) buamanni Mostly Oxidase negative est gene: 309bp in A. iwofii Rapid detection: RapID ONE API 20E TREATMENT Anti-pseudomonas drugs Carbapenem: Imipenem, Meropenem Polymyxin Tigecycline Aminoglycosides  ANTIBIOTIC RESISTANCE Major problem Many MDR strains MDR A. buamanni is common Accumulation of resistance factors (genes) Mechanisms 1. Antibiotics altering enzymes (β-lactam A/B, carbapenems, aminoglycosides) 2. Reduced outer membranes porin expression 3. DNA Gyrase & Topoisomerase IV Mutation (Quinolones) DRUG FOR RESISTANT INFECTIONS Colistin Polymyxin B PREVENTION & CONTROL Hand washing Environmental hygiene Personal hygiene