Nonfermenting GN Rods & Miscellaneous GN Rods MLAB 2434 – Microbiology Keri Brophy-Martinez

General Characteristics of Nonfermenters Nonfermentative organisms that break down carbohydrates oxidatively (aerobically) are also called “oxidizers” or “saccharolytic” Organisms that are NOT able to break down carbohydrates fermentatively or oxidatively are called “biochemically inert,” “nonoxidizers”or nonsaccharolytic

General Characteristics of Nonfermenters (cont’d) Nonfermenters are ubiquitous in the environment Predominantly opportunistic Also isolated in hospitals from nebulizers, dialysate fluids, saline, and catheter devices Somewhat resistant to disinfectants & antibiotics

The Nonfermenters Achromobacter Methylobacterium Acidovorax Moraxella Acinetobacter Agrobacterium Alcaligenes Burkholderia Stenotrophomonas Chryseobacterium Chryseomonas Comamonas Flavimonas Flavobacterium Methylobacterium Moraxella Weeksekka Ochrobactrum Oligella Pseudomonas Psychrobacter Roseomonas Shewanella Sphingobacterium

Clinical Infections Septicemia Meningitis Osteomyelitis Wound infections following surgery or trauma Nosocomial Infections

Clinical Infections Risk factors Immunosuppression Foreign body implantation Traumatic break in a host barrier Antibiotic therapy Underlying disease

Initial Clues to Nonfermenters Long, thin gn rods or cb Oxidase positive (not ALL nonfermenters) No or slow growth of MacConkey agar Nonreactive in 24 hours on commercial kit systems TSI nonreactive Resistant to antibiotics ( penicillin, ampicillin & cephalosporins) Treat with aminoglycosides, quinolones and anti-pseudomonal penicillins ( ticarcillin, piperacillin)

Nonfermenter Organization Nonfermenters are grouped according to three characteristics Growth on MacConkey Not all nonfermenters grow on MAC All nonfermenters that grow on MAC are lactose negative Oxidase reaction OF test

Commonly Encountered Nonfermentative Organisms Pseudomonas characteristics Associated with water and moist environments Not common as normal flora Strict aerobe GN rods or cb Usually motile with polar or polar tufts of flagella Oxidase and catalase positive Usually grows on MacConkey agar Usually oxidizes carbohydrates

Pseudomonas aeruginosa: Clinical Infections Types of infections Bacteremia with ecthyma gangrenosum of skin Wound infections Pulmonary disease (esp. in Cystic Fibrosis) Nosocomial UTI Endocarditis Meningitis Otitis externa (“swimmer’s ear”) “Hot tub” syndrome (skin rash)

Pseudomonas aeruginosa: Virulence Factors Endotoxins Hemolysins Cytotoxins Proteases Slime Pili

P. aeruginosa: Laboratory identification Beta-hemolytic on blood agar Green metallic sheen due to production of pigment pyocyanin (bluish-green) Most strains also produce pigment pyoverdin (yellowish-green fluorescence) Odor described as “grape-like” or “Frito-like”

Honorable mentions… Pseudomonas fluorescens & Pseudomonas putida Produces pyoverdin but not pyocyanin Rarely causes clinical disease Found in water and soil, usually environmental contaminants Pseudomonas stutzeri Wrinkled, leathery colonies that may be light yellow or brown, non- fluorescent

Stenotrophomonas maltophilia Third most common nonfermenter cultured, ubiquitous in nature Common in the hospital environment Implicated in infections of wounds, RT, UT and blood Frequent isolate of Cystic Fibrosis patients

Other Nonfermenters Acinetobacter – found in hospital environments; can cause opportunistic infection, skin/vaginal normal flora. On BAP transluscent-opaque, MAC colorless. On gram stain, short plump gncb Burkholderia cepacia – most often associated with pneumonia in Cystic Fibrosis Burkholderia pseudomallei – causes melioidosis( an aggressive pulmonary disease causing pneumonia, abscesses and septicemia) Alcalingenes – found in water and resistant to disinfectants

References Engelkirk, P. G., & Duben-Engelkirk, J. (2008). Laboratory Diagnosis of Infectious Diseases: Essentials of Diagnostic Microbiology . Baltimore, MD: Lippincott Williams & Willkins. Kiser, K. M., Payne, W. C., & Taff, T. (2011). Clinical Laboratory Microbiology: A Practical Approach . Upper Saddle River, NJ: Pearson Education, Inc. Mahon, C. R., Lehman, D. C., & Manuselis, G. (2011). Textbook of Diagnostic Microbiology (4th ed.). Maryland Heights, MO: Saunders. http://www.microbelibrary.org/library/laboratory-test/2862-blood-agar-plates-and-hemolysis-non-fermenting-gram-negative-rods-including-pseudomonas-aeruginosa