1. Acinetobacter
Before we begin the investigation, we must prepare for field work. The preparation requires that we learn about the organism involved in the outbreak. So prior to going to the hospital, I did some reading about Acinetobacter. This is what I found.

2. Gram negative coccobacillus Frequently arranged in pairs
Oxidase negative
Nitrate negative
Catalase positive
Nonfermentative
Nonmotile
Strictly aerobic
Gram negative coccobacillus
Sometimes difficult to decolorize
Frequently arranged in pairs
Bergogne-Bérézin E, Towner KJ. Clin Microbiol Rev 1996;9:

3. Acinetobacter background
Non-motile gram negative coccobacillus
Often mistaken for staph on bad gram stain
A colonizer of skin & mucosa in the tropics, but not temperate climates
Increased cases in summer perhaps biofilm bloom in tapwater

4. Acinetobacter species and demographics
baumannii
N = 110
other species
N = 90
age mean
median 51 53 58
male
53%
60%
hospital*
>48 hr
76%
57%
speciality*
surgery
ICU
haem/oncol
medicine
21%
20%
15% 8%
10% 2%
24%
18%
infection focus
unknown
40%
35%
49%
32%
species

5. Microbiology Ubiquitous: Survive on moist & dry surfaces 32 species
Widely distributed in nature (soil, water, food, sewage) & the hospital environment
Survive on moist & dry surfaces
32 species
>2/3 of Acinetobacter infections are due to A. baumannii
Highly antibiotic resistant
One of the things that makes this organism so problematic is its widespread presence in the environment and its ability to survive in the hospital environment. Acinetobacter has been cultured from dry surfaces in a patient room more than 9 days after an infected patient was discharged from the room.
Most of the Acinetobacter infections are due to the Acinetobacter baumannii.In addition, it readily acquires antibiotic resistance, even in the same patient.

6. Major infections due to Acinetobacter
Ventilator-associated pneumonia
Urinary tract
Bloodstream infection
Skin/wound infections
Endocarditis
Peritonitis
Acinetobacter most commonly causes pneumonia, particularly ventilator-associated pneumonia. However, it has also been cultured from blood, urine, and wounds. It may less frequently cause meningitis, peritonitis, or endocarditis.

7. Acinetobacter Ventilator-Associated Pneumonia
Acinetobacter accounts for 5-25% of all cases of VAP
Risk factors:
Advanced age
Surgery
Use of antimicrobial agents
Invasive devices
Prolonged ICU stay
Some of the factors associated with previous outbreaks of Acinetobacter-associated pneumonia include one or multiple surgeries, patient requirement for multiple antibiotics, the use of devices such as central venous lines or arterial lines, and a long stay in the intensive care unit, such as with a critically ill trauma patient.

8. Acinetobacter on Gram stain

9. Source of A. baumanii Nosocomial Bloodstream Infection
Abdominal infection
19%
The respiratory tract is an important reservoir for Acinetobacter bloodstream infections
Central venous
line 8%
Respiratory tract
71%

10. Inflammatory Response to A. baumanii Nosocomial Bloodstream Infection
Severe sepsis
21%
Septic shock
24%
Sepsis
55%

11. Opportunities for cross transmission are multiple

12. Preventing Acinetobacter Transmission in the ICU General Measures
Hand hygiene
Use of alcohol-based hand sanitizers
Contact precautions
Gowns/gloves
Dedicate non-critical devices to patient room
Environmental decontamination
Prudent use of antibiotics
Avoidance of transfer of patients to Burn Unit from other ICUs

13. Preventing Acinetobacter Transmission in the ICU Outbreak Interventions
Hand cultures
Surveillance cultures
Environmental cultures following terminal disinfection to document cleaning efficacy
Cohorting
Ask laboratory to save all isolates for molecular typing
Healthcare worker education
If transmission continues despite above interventions, closure of unit to new admissions

14. Summary
Although commonly found on the skin of healthy humans, Acinetobacter plays the role of an opportunistic pathogen in the critically ill patient
High level of antibiotic resistance makes it well suited as a pathogen in areas with high use of antibiotics (e.g., ICU setting)
Control requires good hand hygiene, barrier precautions & environmental decontamination
Alcohol-based products containing chlorhexidine should be considered the hand hygiene agents of choice

16. Oxidation-fermentation Hugh-Leifson - Uninoculated

17. OF glucose oxidative metabolism

18. OFglucose fermentative metabolism (Enlarged view)

19. Identification characteristics of Acinetobacter baumanni (Unknown)

20. Reaction
Test -
Oxidase
K/K
KIA
TSI +
Growth on MAC
Motility
OF-glucose
OF-lactose
Urea
Growth at 42 C
Nitrate
Hemolysis
Arginine
Malonate
Gelatin hydrolysis