Chapter 20: Acinetobacter

Question 1

General characteristics of Acinetobacter and Stenotrophomonas

Answer 1

Non-Lactose fermenting
Gram- negative
Oxidase: negative
They are MacConkey Positive meaning that they have an ability to grow on MAC agar except for the CDC group NO-1 ( a rare group of fastidious, non-fermenting, nonoxidizing gram negative bacilli)

Question 1

What are the characteristics of Acinetobacter?

Answer 1

Non-Lactose fermenting
Gram- negative
Oxidase: negative
They are MacConkey Positive meaning that they have an ability to grow on MAC agar except for the CDC group NO-1 ( a rare group of fastidious, non-fermenting, nonoxidizing gram negative bacilli)

Question 2

Differentiate between saccharolytic and asaccharolytic

Answer 2

Saccharolytic: Organisms that oxidize glucose
Asaccharolytic: Organisms that don’t use glucose

Question 3

Briefly describe where Acinetobacter are normally found and also mention the mode of transmission for this bacteria

Answer 3

Habitat: Acinetobacter are normally found in nature and associated with nosocomial infection, it is said that they are found in the skin and respiratory microbiota of patients that where hospitalized for long periods of time

Mode of transmission: They are transmitted through medical instrumentation(intravenous or urinary catheters)

Question 4

Describe where Stenotrophomonas maltophilia are commonly found and also describe the Mode of transmission associated with this organism

Answer 4

Habitat: Why are usually found in nature and in hospital settings they can be found in the respiratory biota and skin of patients that where hospitalized for long periods of time

Mode of transmission: They are mostly associated with nosocomial infections where they spread through medical devices( intravenous and urinary catheters)

Question 5

What are the Morphological characteristics of Acinetobacter

Answer 5

Oxidase: Negative
Small, plump gram-negative coccobacilli that are mostly mistaken as coccus for un-trained eye ( Neisseria spp are the only true cocci in gram negative bacteria )
Blood Agar: Smooth, opaque, raised and creamy colonies with no hemolysis
MacConkey agar: Non-Lactose fermenter with purplish hue(purple hue because of the ability to resist acetone and may often be mistaken as Lactose fermenters to unexperienced people)

Question 6

What are the Morphologic Characteristics of Stenotrophomonas

Answer 6

Short to medium-sized gram negative straight rods
Blood Agar: Smooth, opaque, raised, creamy
MacConkey agar: Non-Lactose fermenters

Question 7

What are the specimen requirements for the Acinetobacter and the Stenotrophomonas

Answer 7

Where are no specimen requirements for these species because they are capable of growing in any agar and any incubation will allow them to grow

Question 8

What are the biochemical test used for S.maltophilia ?

Answer 8

Oxidase: Negative
Catalase positive
Rapid MALTOSE oxidizer in Aerobic incubation*
It is motile due to the presence of Polar flagella

Question 9

What are the risk factors associated with S.maltophilia

Answer 9

>central venous catheterization 
> Cystic fibrosis 
>Patients what are in ICU 
>Malignancy 
>HIV patients

Question 10

What are the risk factors of patients with Acinetobacter

Answer 10

> Intensive-care unit patients (ICU)
Patients that are residing in long-term facilities
Central venous catheters

Question 11

What are the Virulence factors for Acinetobacter

Answer 11

They have the ability to produce a lipopolysaccharide capsule which has the ability to survive in dry environments and adhere to mucosal epithelium via the fimbriae