Acinetobacter baumannii

Maliha Talib MB 360 (Lee)

Spring 2014

•Traced back to Vietnam War•Recent outbreak during Iraq War•Original outbreak from Europe•>> 700 soldiers effected

Origination

General InformationTaxonomic Classification: •Bacteria; Proteobacteria; Gammaproteobacteria; Pseudomonadales; Moraxellaceae; Acinetobacter

Microbiologic Morphology: •gram negative •aerobic •cocco-bacillus•encapsulated•nonmotile •catalase-positive•oxidase-negative

Catalase = positive The purpose is to see if the microbe has catalase or can destroy chemical hydrogen

peroxide.

Oxidase = negative Identifies organisms that

produce the enzyme cytochrome oxidase.

General Information

General InformationHabitat•soil, water, food, sewage, & the hospital environment•resistant to desiccation and disinfection•Survive on moist & dry surfaces•forms bio-film on catheters, ventilators, and other medical devices•Iraq/Afghanistan

General Information

General Information

Nutrition•grows on various media •can live in hospital settings 9 days after patient leaves•Acinetobacter calcoaceticus-baumanii complex: glucose-oxidising nonhemolytic, •Acinetobacter lwoffii: glucose-negative nonhemolytic •Acinetobacter haemolyticus: haemolytic on blood agar.

General Information

PathogenesisDiseases•Bloodstream infections: pneumonia, urinary tract infections, and septicemia•mostly respiratory >> can lead to death •32 species: cause of 80% of infections •nosocomial

Examples of Major Infections•Ventilator-associated pneumonia •Urinary tract•Bloodstream infection •Secondary meningitis•Skin/wound infections•Endocarditis•CAPD-associated peritonitis•Ventriculitis

Pathogenesis

Pathogenesis

Transmission •spread via person to person OR •contact with contaminated environment

Pathogenesis

Pathogenesis

• Bed rails• Bedside tables• Ventilators• Infusion pumps• Mattresses• Pillows• Air humidifiers• Patient monitors

• X-ray view boxes• Curtain rails• Curtains• Equipment carts• Sinks• Ventilator circuits• Floor mops

Transmission

Pathogenesis

Mechanisms •Aminoglycosides-modifying enzymes •Broad-spectrum β-lactamases •Carbapenemases •Quantitative and/or qualitative changes in outer membrane porins •Altered penicillin-binding proteins.

Pathogenesis

Circular map of A. baumannii genome.

Smith M G et al. Genes Dev. 2007;21:601-614

Copyright © 2007, Cold Spring Harbor Laboratory Press

Pathogenesis

Pathogenesis

Symptoms•standard infection symptoms i.e. fever•death within 14 days of surgery

Predisposed factors •Malignancy•Trauma•Burns•Surgical wound infections•Neonates •Low birth weight•Need for mechanical ventilation

Diagnosis•clinical culture of blood, sputum, urine, wound, sterile body fluid, etc.

Factors leading to the emergence and transmission of multidrug-resistant (MDR) Acinetobacter species.

Eliopoulos G M et al. Clin Infect Dis. 2008;46:1254-1263

© 2008 by the Infectious Diseases Society of America

Treatment • Will collect: age, sex, occupation, hospital location at the time of positive culture (ER, medical ward, ICU etc), date of positive culture, prior hospitalization, receipt of outpatient dialysis, home care or other regular medical care (eg, outpatient chemotherapy), presence of invasive devices, receipt of antibiotics, etc.•Carbapenems (Imipenem and Meropenem) - growing resistance•Others: Polymyxin, Tigecycline and Aminoglycosides

Pathogenesis

Pathogenesis

Pathogenesis

Methods for control and prevention of multidrug-resistant Acinetobacter infection.

PathogenesisPrevention: •Wash hands•contact precautions•environmental decontamination

Antibiotic Resistance •naturally transformable•AcomFECB and comQLONM allow uptake of DNA from the environment •administration of subtheraputic doses of antimicrobial agents, drug overuse, interrupted courses of treatment, and poor tissue penetration by antimicrobial agent•Medical interventions increasing the Acinetobacter Infections

• Most A. baumannii resistant: tampicillin, Carbenicillin, Cefotaxime and Chloramphenicol.

• Increasing resistance:Gentamycin, tobramycin and amikacin is increasing.

• May retain: Fluoroquinolones, ceftazidime,Trimethoprim-Sulphmethoxazole, Doxycycline, Polymyxin B, colistin, imipenem and meropenem

Antibiotic Resistance

"Acinetobacter baumannii membrane transporter PilQ allows initial entry of foreign DNA into the cell. Foreign DNA is then bound by protein ComE and is directed to cytoplasmic membrane transporter ComA."

Antibiotic Resistance

Sent troops to Iraq

Bush's increase of troops to protect Baghdad and Al Anbar Province

Antibiotic Resistance

Cost of Outbreak

Works Cited•Federico Perez, Andrea M. Hujer, Kristine M. Hujer, BrookeK. Decker, Philip N. Rather and Robert A. Bonomo Antimicrob. Agents Chemother. 2007, 51(10):3471. DOI:10.1128/AAC.01464-06. Published Ahead of Print 23 July 2007. •George M. Eliopoulos, Lisa L. Maragakis, and Trish M. Perl Acinetobacter baumannii: Epidemiology, Antimicrobial Resistance, and Treatment Options Clin Infect Dis. (2008) 46 (8): 1254-1263 doi:10.1086/529198•Hujer, K. Hujer, A. Hulten, E. Bajaksouzian, S. Adams, J. Donskey, C. Ecker, D. Massire, C. Eshoo, M., Sampath, R., Thomson, J. Rather, P., Craft, D., Fishbain, J., Ewell, A., Jacobs, M. Paterson, D., Bonomo, R. “Analysis of Antibiotic Resistance Genes in Multidrug-Resistant Acinetobacter sp. Isolates from Military and Civilian Patients treated at the Walter Reed Army Medical Center.” Antimicrboia Agents and Chemotherapy. Dec. 2006. Volume. 50, No. 12. 4114-4123.•José M. Cisneros, Maria J. Reyes, Jerónimo Pachón, Berta Becerril, Francisco J. Caballero, José L. García Garmendia, Carlos Ortiz, and Adelaido R. Cobacho Bacteremia Due to Acinetobacter baumannii: Epidemiology, Clinical Findings, and Prognostic Features Clin Infect Dis. (1996) 22 (6): 1026-1032 doi:10.1093/clinids/22.6.1026•Lenie Dijkshoorn, Alexandr Nemec & Harald Seifert An increasing threat in hospitals: multidrug-resistant Acinetobacter baumannii Nature Reviews Microbiology 5, 939-951 (December 2007) doi:10.1038/nrmicro1789•Mortensen, B. L. and Skaar, E. P. (2012), Host–microbe interactions that shape the pathogenesis of Acinetobacter baumannii infection. Cellular Microbiology, 14: 1336–1344. doi: 10.1111/j.1462-5822.2012.01817.x