PSEUDOMONADS, ACINETOBACTERS AND OTHER UNCOMMON GRAM

NEGATIVE BACTERIA

ALLAN JAY C. ESPIRITU, RMT, M.Sc.

The Pseudomonad Group

Morphology

Oxygen Requirement

Sugar fermentation

Important members:

Pseudomonas spp.

Burkholderia spp.

Stenotrophomonas spp.

ALLAN JAY C. ESPIRITU, RMT, M.Sc.

Classification of Some of the

Medically Important Pseudomonads rRNA Homology Group

and Subgroup Genus & Species

I Fluorescent Group

Nonfluorescent Grp. P. aeruginosa, P. fluorescens, P. putida

P. stutzeri, P. mendocina

II B. pseudomallei, B. mallei, B. cepacia,

R. pickettii

III Comamonas species, Acidovorax species

IV Brevundimonas species

V Stenotrophomonas maltophilia

ALLAN JAY C. ESPIRITU, RMT, M.Sc.

Pseudomonas aeruginosa

Morphology

Flagellation

Strict aerobes

Oxidase

Good growth on MAC

ALLAN JAY C. ESPIRITU, RMT, M.Sc.

Gram stain of P. aeruginosa

ALLAN JAY C. ESPIRITU, RMT, M.Sc.

P. aeruginosa

Habitat

Environmental water sources (e.g. hospital

respirators & humidifiers)

May inhabit skin, URT and colon

Transmission

Water aerosols, aspiration and fecal

contamination

ALLAN JAY C. ESPIRITU, RMT, M.Sc.

P. aeruginosa Pathogenicity/Virulence

Pili

Exotoxin A – diphtheria-like toxin

Endotoxin

Diseases

Wound infections

Ecthyma gangrenosum

UTI

Pneumonia in cystic fibrosis

Nosocomial infections in burn patients

Bacteremia and sepsis

ALLAN JAY C. ESPIRITU, RMT, M.Sc.

Ecthyma gangrenosum

ALLAN JAY C. ESPIRITU, RMT, M.Sc.

Lab. Diagnosis of P. aeruginosa

Microscopic

Cultural: “grape or tortilla corn”

Biochemical

Oxidase

Growth at 42oC

Hydrolysis of acetamide

Growth on cetrimide agar

Nitrate reduction

ALLAN JAY C. ESPIRITU, RMT, M.Sc.

P. aeruginosa

ALLAN JAY C. ESPIRITU, RMT, M.Sc.

Pigments Produced by P.

aeruginosa

Pyocyanin

Pyoverdin

Pyorubrin

Pyomelanin

ALLAN JAY C. ESPIRITU, RMT, M.Sc.

Epidemiology of P. aeruginosa

Treatment

Ticarcillin/Piperacillin with tobramycin

Aztreonam, imipinem, ciprofloxacin

Ceftazidime and cefoperazone

Prevention

Moist environments: sinks, showers, tubs,

etc.

Control

Vaccine from appropriate types

ALLAN JAY C. ESPIRITU, RMT, M.Sc.

Other Pseudomonas species

P. fluorescens and P. putida

Pyocyanin production

Hydrolysis of acetamide

Nitrate reduction

Growth at 42oC

P. fluorescens is positive for gelatinase and

lecithinase, P. putida is negative to both.

Diseases

Respiratory infection, wound infection and UTI

ALLAN JAY C. ESPIRITU, RMT, M.Sc.

Burkholderia species

Burkholderia pseudomallei

Morphology

Oxidase test

Disease: MELIOIDOSIS

A.k.a. _____________________________

Commonly a pulmonary infection, primarily

a pneumonitis

ALLAN JAY C. ESPIRITU, RMT, M.Sc.

Burkholderia species

Burkholderia mallei

Morphology

Oxidase test

Causes GLANDERS in horses

May be transmitted to man

Cutaneous involvement with thickening of the

superficial lymphatics

Burkholderia cepacia

May cause pneumonia, UTI and other

infections

Oxidase test

Potent nosocomial infection in cystic fibrosis

patients ALLAN JAY C. ESPIRITU, RMT, M.Sc.

Other Pseudomonads

Stenotrophomonas maltophilia

Nosocomial LRTI

Oxidase negative, motile, LDC (+), DNAse

(+), oxidizes OF maltose (maltophilia)

Shewanella putrifaciens

Only nonfermentor that produces H2S in TSI

ALLAN JAY C. ESPIRITU, RMT, M.Sc.

The Acinetobacter

Important members

A. baumannii, A. lwoffi, A. johnsonii, A.

haemolyticus

Habitat

Skin, oropharynx, vagina

Diseases

UTI, LRTI

Lab. Diagnosis

G(-) coccobacilli to diplococci, Oxidase (-), non-

motile

A. baumannii produces acid from 10% lactose

A. lwoffi is asaccharolytic

ALLAN JAY C. ESPIRITU, RMT, M.Sc.

Uncommon G(-) Bacteria

Moraxella

M. lacunata

M. nonliquifaciens

M. osloensis

M. phenylpyruvica

Chryseobacterium (Flavobacterium)

C. indologenes – wound infection

C. meningosepticum – neonatal meningitis

Produces yellow-pigmented colonies on BAM

ALLAN JAY C. ESPIRITU, RMT, M.Sc.

Uncommon G(-) Bacteria

Alcaligenes

A. faecalis

A. xylosoxidans spp. xylosoxidans

A. xylosoxidans spp. denitrificans

Eikenella

E. corrodens

Normal inhabitant of oral cavity and URT of

humans

Causes gingivitis, tooth infection, neck & facial

abscess, pneumonia, clinched fist injury,

bacteremia

BAP: bleach-like odor

ALLAN JAY C. ESPIRITU, RMT, M.Sc.

Uncommon G(-) Bacteria

Streptobacillus moniliformis GNR in chains with irregular bulbous swelling

Grown on HI agar or broth

Causes Rat bite fever (Haverhill disease)

Spirillum minor Small G(-) spiral shaped rods

Darkfield microscopy

Causes Rat bite fever (Soduku)

Calymmatobacterium granulomatis Causes granuloma inguinale

Diagnosis: Donovan bodies in Wright’s stain

ALLAN JAY C. ESPIRITU, RMT, M.Sc.

Uncommon G(-) Bacteria

Bartonella bacilliformis

Transmission: Phlebotomus sandfly (vector)

Causes Carrion’s disease

Oroya fever: severe febrile anemia

Verruga peruana: nodular disease of

cutaneous tissues

Cardiobacterium hominis

Dumb-bell shaped GNR

Causes endocarditis

ALLAN JAY C. ESPIRITU, RMT, M.Sc.