Pseudomonas

MICR O

PSEUDOMONAS

Pseudomonas -

150 species, saprophytic >25 species associated with humans Gm (-), aerobic bacilli, NLF 0.5 to 0.8μm x 1.5 to 3μm

-

Motility by a single polar flagellum

-

Distinguished by biochemical and DNA hybridization tests

BACTERIA

EPIDEMIOLOGY

A. Cell Envelope 3 Layers 1. Inner or cytoplasmic membrane 2. Peptidoglycan layer 3. Outer membrane o Phospholipid o Protein o LPS B. Colony Types 1. natural isolates from soil or water small, rough colony 2. clinical samples – play a role in colonization and virulence a. fried egg appearance  large, smooth, flat edges and

A. Growth Requirements Very simple nutritional requirements Grow in distilled water Organic growth factors not required Optimum temperature for growth is 37° o able to grow at T as high as 42° - R to high conc of salts, dyes, weak antiseptics, and many commonly used antibiotics Inhabits soil, water, vegetation found in skin, throat, stool B. Reservoirs Disinfectants, respiratory equipment,

COLONIZATION/ INVASION/ DISSEMINATION

CLINICAL MANIFESTATION/DISEAS ES

A. Colonization - Fimbriae  adhere to epithelial cells of URT  adhesions bind to specific galactose or mannose or sialic acid receptors on epithelial cells - Colonization requires fibrial adherence aided by production of protease enzyme  degrades fibronectin to expose fimbrial receptors Receptor on tracheal epithelial cells for pseudomonas pili (sialic acid) Mucoid strains (produce alginate) have additional or alternative adhesion attaches to trachebronchial mucin Exoenzyme S serve as an adhesion for

Clinical Manifestations disease is rare in healthy individuals only causes chronic otitis externa disease most often occurs in people with natural immunologic deficiency immunosuppressive therapy burns disease most often occurs in people with o chronic pulmonary disease (CF) o IV narcotic use o Renal dialysis most common site of infection o urinary tract o burns infections take the form of: o septicemia, abscesses, corneal infections,

...One who does not sacrifice anything cannot achieve anything.

PATHOGENESIS/ VIRULENCE FACTORS Adhesins fimbriae (Nmethylphenylalaninepili) polysaccharide capsule (glycocalyx) alginate slime (biofilm) Invasins elastase alkaline protease hemolysins o phospholipase o lecithinase cytotoxin (leucocidin) siderophores and siderophore uptake systems pyocyanin diffusible pigment Motility / Chemotaxis flagella Toxins Exoenzyme S Exoenzyme A Lipopolysaccharide Antiphagocytic surface properties

^_^ shar ^_^ 1

BIOCHEMICAL PROPERTIES/ LAB DIAGNOSIS •

Grows well on most lab media o NFL o Oxidase o Beta – hemolytic o Characteris tic odor (fruity  grapes) o Color: blue; fluorescenc e under UV o Motile o Ability to grow 42 °C

MANAGEMENT/ TREATMENT/ PREVENTION Treatment • Combination o Anti pseudomon al Penicillin + Aminoglyco side Prevention • Proper isolation procedures • Use good aseptic technique in hospital instruments when in contact with patients • Topical therapy of burn wounds with antibacterial

MICR O

PSEUDOMONAS

b.

elevated mucoid appearance  alginate slime from respiratory and urinary tract secretions

-

food, sinks, taps, mops Constantly reintroduced into the hospital environment on fruits, plats vegetables, visitors and patients from other facilities

C. Transmission o Hands of personnel o Direct patient contact with contaminated reservoir o Ingestion of contaminated foods and water

-

-

glycolipids on respiratory cells Alginate forms the matrix of Pseudomonas biofilm – anchors the cells to their environment  protects the bacteria from host defenses  less S to antibiotics than their planktonic counterparts Mucoid strains are most often isolated from patients with cystic fibrosis

B. Invasion Depends upon production of extracellular enzymes and toxins that break down physical barriers and damage host cells, R to phagocytosis and host immune defenses Bacterial capsule or slime layer effectively protects cells form opsonization by antibodies, complement deposition and phagocyte engulfment 2 Extracellular Proteases o Elastase + Alkaline protease o Cause inactivation of gamma interferon (IFN)

...One who does not sacrifice anything cannot achieve anything.

-

memingitis, bronchopneumonia, SBE treatment often fails with >80% mortality

Diseases 3 Distinct Stages 1. bacterial attachment 2. local invasion 3. disseminated systemic disease Endocarditis infects heart valves of IV drug users and prosthetic heart valves establishes itself on the endocardium by direct invasion from the blood stream Respiratory Infections compromised LRT or systemic defense mechanism o Primary pneumonia  Chronic lung disease and CHF o Bacteremic pneumonia  Neutropenic cancer patients undergoing chemotherapy o LRT colonization of cystic fibrosis o Patients of mucoid strains o Difficult, if not possible to treat

-

capsule, slime layers LPS

Defense against serum bactericidal reaction slime layers, capsules LPS Protease enzymes Defense against immune responses capsule, slime layers protease enzymes Genetic attributes genetic exchange by transduction and conjugation inherent drug resistance R factors and drug R plasmids Ecologic criteria adaptability to minimal nutritional requirements metabolic diversity widespread occurrence in a variety of habitats Pathogenesis B. Deficiencies in colonization 1. Burns 2. Lungs: requires compromised lung (CF) C. Alginate (exopolysaccharide) o Viscous gel around bacteria o Coating may protect from phagocytosis in lung infections o Produces septicemia in neutropenics D. Adhesion 1. Pili: type 4  Similar:  N. gonorrhea

^_^ shar ^_^ 2

agents + surgical debridement

MICR O

PSEUDOMONAS

and tumor necrosis factor (TNF) 3 Other Soluble Proteins o Cytotoxin (MW 25kDa) (leukocidin)  Pore-forming protein 2 Hemolysins o Phospholipase o Lecithinase o Act synergistically to break down lipids and lecithin o Contribute to invasion through their cytotoxic effects on eukaryotic cells Pigment o Pyocyanin Impairs normal function of human nasal cilia Disrupts respiratory epithelium Exerts proinflammatory effect on phagocytes o Pyoochelin – siderophore Derivative of pyocyanin Produced under low iron conditions to sequester iron form the environment for growth of the pathogen o Fluorescent pigment No role

...One who does not sacrifice anything cannot achieve anything.

Bacteremia and Septicemia • Bacteria in immunocompromised patients • Predisposing factors: o Hematologic malignancies o Immunodefici ency relating to AIDS o Neutropenia, DM, severe burns • Accounts for 25% of all hospital acquired gram (-) bacteremias Central Nervous System Infections • Meningitis, abcesses • Invades the CNS from a contiguous structure (inner canal, paranasal sinus) • Inoculated directly by means of head trauma, surgery or invasive diagnostic procedure • Spreads from a distant site of infection (urinary tract) Ear Infections including otitis externa • Predominant bacterial pathogen in some cases of external

 V. cholerae Tcp pili Methylated phenylalanine  1st aa of pilin subunit  Bind preferentially to asialoGM1  Preceded by removal of sialic acid by neuraminidase  better receptor, bind to epithelial cells, not mucin 2. Nonpilus adhesions 2 Types - bind to:  mucin/epithelial cells  mucin only 

E. Exoenzyme S 1. ADP-ribosylation for intermediate filaments, GTP-binding proteins (Ras) involved in signal transduction systems 2. Exogenously applied ExoS does not injure tissue culture cells, no evidence that ExoS binds host cells, internalized; must be activated by host cell protein 3. Disruption of gene raises LD50 for burned mouse from 30 cfu to 105 cfu (colonized locally as well as wild type, did not produce septicemia) 4. detection of ExoS in blood before septicemia in colonization by wild type  may have a role in damage to phagocytes which would otherwise spread to blood

^_^ shar ^_^ 3

MICR O

PSEUDOMONAS

C. Dissemination mediated by the same cell associated and extracellular products responsible for the localized disease R to phagocytosis and the serum bactericidal response due to its mucoid capsule and possible LPS Lipid A moiety of LPS (endotoxin) mediates the usual pathologic aspects of Gm(-) septicemia

•

otitis including “swimmer’s ear” Infrequently found in the normal ear, but often inhabits the external auditory canal in association with injury, maceration, inflammation or simply wet and humid conditions.

Eye Infections • One of the most common cause of bacterial keratitis • Isolated as etiologic agent of neonatal opthalmia • Colonize the ocular epithelium by means of fimbrial attachment to sialic acid receptors • If defenses of the environment are compromised in any way, the bacterium can proliferate rapidly and through the production of enzyme elastase, alkaline protease and exotoxin A  rapidly destructive infection loss of entire eye. Bone and Joint Infections • Direct inoculation of the bacteria of the hematogenous spread of the bacteria from

...One who does not sacrifice anything cannot achieve anything.

5.

ExoS neg strains colonize lungs, no extensive damage like WT

F.

Exotoxin A 1. same mechanism as DT  antibodies vs DT do not react with ExoA and vice versa, different receptors  RXN = ExoA + NAD + EF2 Adp-ribosyl-EF2 + nicotinamide + H 2. internalization/activation of ExoA  same as DT, regulation y iron 3. present in most clinical isolates  those without = less virulent G. Elastase o enzyme system which degrades elastin = maj component of lung H. Phospholipases C (2) o hemolytic and nonhemolytic I. Leucocidin lethal for WBC, but nonhemolytic J. Pigments in 90% o used a diagnostic feature o involved in iron acquisition o pyocyanin – “pyocyaneus” to “blue pus”  antibacterial (suppresses growth)  may aid in colonization  damages endothelial tissue in vitro  mediates conversion of superoxide to hydroxyl

^_^ shar ^_^ 4

MICR O

PSEUDOMONAS

•

•

•

•

other primary sites of infection Blood borne infections: o IV drug users o In conjunction with the urinary tract or pelvic infections Particular tropism for the fibrocartilagenous joints of the axial skeleton Causes chronic contiguoug osteomyelitis resulting for the direct inoculation of bone Most common pathogen implicated in osteochondritis after puncture wounds of the foot

Urinary tract Infections • Hospital acquired • Related to urinary tract catherization, instrumentation or surgery • 3rd leading cause of hospital acquired UTIs- 12% of all infections of this type • Most adherent of common urinary pathogens to bladder epithelium • Can occur via an ascending or descending route

...One who does not sacrifice anything cannot achieve anything.

o

pyoverdin – fluoresces in tissue K. Broadly resistant to antibiotics o due to permeability barrier afforded by its outer membrane LPS o tendency to colonize surfaces in a biofilm form makes the cells impervious to therapeutic conc antibiotics o may be plasmid mediated Toxigenesis Extracellular protein toxins Exoenzyme S o Produce by bacteria growing in burned tissue o Detected in the blood before the bacteria are o Impair function of phagocytic cells in the blood stream and internal organs to prepare for invasion by P. aeruginosa Exotocin A o Exactly same mechanism of action as the diphtheria toxin o Partially identical to diphtheria toxin but antigenetically distinct o Utilizes a different receptor on host cells o Production regulated by exogenous iron o Mediate both local and systemic disease o Necrotizing activity at site of bacterial colonization cause more virulent form of pneumonia

^_^ shar ^_^ 5

MICR O

PSEUDOMONAS

•

Can invade the bloodstream from the urinary tract – source of nearly 40% of Pseudomonas bacteremias Gastrointestinal Infections • Can produce disease from oropharynx to the rectum • Occur primarily in immunocompromised individuals implicated in perirectal infections, pediatric diarrhea, typical GE, NEC (huh?) • Important portal entry in P. septicemia SSTI, wound infections, pyoderma and dermatitis • Localized and diffused • Predisposing factors: o Breakdown of the integument which may result from burns, trauma or dermatitis o High moisture conditions  Ear of swimmers  Toe webs of athletes and combat troops  Perineal region, under diapers of

...One who does not sacrifice anything cannot achieve anything.

^_^ shar ^_^ 6

MICR O

PSEUDOMONAS



 

...One who does not sacrifice anything cannot achieve anything.

infacts Skin of whirlpool and hot tub users AIDS Implicated in folliculitis and acne vulgaris

^_^ shar ^_^ 7