1. AEROBIC GRAM-NEGATIVE BACTERIA: NONFERMENTATIVE GRAM-NEGATIVE BACILLI

AEROBIC GRAM-NEGATIVE BACTERIA:

D. NONFERMENTATIVE GRAM-NEGATIVE BACILLI

General Characteristics

a. Found in water, soil, ____, and ____, and a few are normal biota of humans

b. Approx ____ of all gram-negative bacilli isolates are nonfermentative gram-negative bacilli (NFB)

a. Found in water, soil, food, and plants, and a few are normal biota of humans

b. Approx 20% of all gram-negative bacilli isolates are nonfermentative gram-negative bacilli (NFB)

• Most species are obligate aerobes

• Do not metabolize carbohydrates under anaerobic conditions (fermentataion)

Nonfermentative gram-negative bacilli (NFB)

• MOST are Oxidase = POSITIVE

• TSI: K/No change

• Grow on SBA but varied growth on MAC

Nonfermentative gram-negative bacilli (NFB)

• Most important NFB 

• Along with it members, produces fluorescein (pyoverdin)

• Common clinical isolate that can infect humans, animals, plants, and fish

• Causes eye (conatct lens) and ear infection - responsible for “swimmer’s ear” which is an external otitis

Pseudomonas aeruginosa

• Lower respiratory tract infection in patients with Cystic fibrosis

• Causes burn wound infection

• Resistant to a number of disinfectants

• Associated with hospital environments and equipment, whirlpools, and swimming pools

• Very resistant to antimicrobial agents: Aminoglycosides and carbapenams are often used for treatment

Pseudomonas aeruginosa

1. Large, irregular colonies with a grape-like odor and metallic sheen on SBA

2. BETA-HEMOLYTIC colonies with a feathery edge on SBA

3. Mucoid colonies

4. Produces PYOCYANIN 

5. Oxidase, Motility = POSITIVE 

6. Lactose = NEGATIVE 

7. Ocidizes glucose 

Pseudomonas aeruginosa

• Acquired as transient biota from hospitals

• Causes pneumonia, UTI, wound infection

• Resistant to most antimicrobials

• Oxidase = NEGATIVE , Maltose = POSITIVE

Stenotrophomonas maltophilia

• Formerly called as Pseudomonas cepacia

• Causes healthcare- associated Infections

• Also an important respiratory tract pathogen in patients with CF, secondto P,aeruginosa

Burkholderia cepacia

• Colorless or Yellow on Nutrient Agar

• Oxidase, Lactose = POSITIVE

• Enhanced growth P.cepacia (PC) Agar: which inhbits P.aeruginosa

• Nutrient Agar: colorless or yellow

Burkholderia cepacia

• Considered a Potential Bioterrorism agent

• Causes “Glanders”, a highly contagious disease of livestock particularly among horses, dogs, and mules

• Can be transmitted to humans by animal contact

Burkholderia mallei

• Oxidase = VARIBALE 

• Motility = NEGATIVE 

• Reduces NITRATE to NITRITE without gas 

• Oxidizes glucose 

• Grows on MAC Agar 

Burkholderia mallei

• Oxidase = POSITIVE 

• Motility = POSITIVE 

• Oxidizes several sugars including glucose and lactose 

• Grows on MAC Agar

Burkholderia pseudomallei

• Found in soil

• Acquired through the

• Skin or by inhalation

• Causes “Melioidosis” , a disease of humans and animals endemic to Southeast Asia and Northern Australia

Burkholderia pseudomallei

• Found as a normal biota of the GI and

• Respiratory tracts

• Important cause of healthcare- associated infections

• Isolates tend to be multi-drug resistant

• Important in the intensive care setting

Acinetobacter

• Obligate aerobe; Coccobacillus

• Oxidase, Motility, Nitrate = NEGATIVE 

• Catalase = POSITIVE 

• Grow on most media

• May resemble enterics on MAC and EMB Aga

Acinetobacter

• Opportunistic pathogen

• Asaccharolytic

Alcaligenes