1) Acinetobacter baumannii is a gram-negative bacterium that can cause a variety of healthcare-associated infections. It has emerged as an important nosocomial pathogen due to its ability to develop resistance to multiple antibiotics. 2) In Tanzania, studies have found A. baumannii among isolates from patients with urinary tract infections, surgical site infections, and burn wound infections. Isolates from Tanzanian hospitals have shown high levels of resistance to many front-line antibiotics. 3) The optimal treatment of multi-drug resistant A. baumannii infections is challenging due to its extensive antibiotic resistance. Active surveillance of patients and environmental surfaces is important to control the spread of this problematic

1. Acinetobacter
baumannii
Salim S Masoud

2. Introduction
•The name “Acinetobacter” comes from the
Latin word for motionless –
•Lacks cilia or flagella with which is required to
move
•According to CDC: A. baumannii causes
80% of all Acinetobacter infection

3. Other species
•A. baumannii is the major species of
Acinetobacter
•Other human pathogens include:
1. A. calcoaceticus
2. A. lwoffi
3. A. junii
4. A. johnsonii
5. A. baylyi

4. Background
•Acinetobacter baumannii was
a low category pathogen in the
past and has emerged as an
infectious pathogen
•In 1990 during the Iraq War;
Iraqnobacter (Acinetobacter
baumannii) caused more
deaths in soldiers than the
trauma on the battlefield

5. Origin of Iraqibacter
•Soil samples taken by
researchers in Iraq and
Kuwait which were
negative
•However, Iraqnobacter
was found thriving in the
hospital

6. Iraqnobacter among US soldiers
•Some nurses, soldiers infected with
Iraqnobacter (A. baumannii) due to its spread
throughout the military hospitals
•Many times soldiers have survived trauma on
battlefield only to succumb to more damage by
an organism with antimicrobial resistance
factors to drugs

7. Transmission of Acinetobacter
• Acinetobacter spp. has a low
virulence and often reflects as
a colonisation opposed to
infection
• Causes infection in
immunocompromised, chronic
diseased, surgical wounded,
previous antibiotic use and
prolonged hospital admitted
individuals
• Can survive in natural
environment with minimal
needs: air, food, water,
sewage

8. Background
• Acinetobacter spp. are pleomorphic, aerobic,
non-motile, gram-negative coccobacillus
• Commonly isolated from hospital environment
and hospitalised patients; found in Intensive Care
Units and Burn Units: Opportunistic Pathogen
• Acinetobacter spp. can cause bacteraemia, HAP,
meningitis, UTI, traumatic and wound infections

9. Public Health Priority
• IDSA - 2009 categorised Acinetobacter baumannii in
the ESKAPE acronym which represents: Escherichia
coli, Staphylococcus aureus, Klebsiella pneumoniae,
Acinetobacter baumannii, Pseudomonas aeruginosa
and Enterobacter spp
• CDC categorises Multi-drug Resistant (MDR)
Acinetobacter baumannii as a threat to public health
• WHO - 2017 categorises Acinetobacter baumannii
as a Critical Priority bacteria in the Global Priority
Pathogen List

10. WHO: Global Priority Pathogen List

11. Microbiological Properties
• Oxidase – negative
• Indole – negative
• Catalase – positive
• Do not reduce nitrate
• Do not ferment
glucose
• Non-motile
• Citrate – positive
•Usually non-lactose
fermenting (however,
some strains are
lactose fermenting)
•Direct Stain from blood:
gram positive cocci
•Culture Gram Stain:
gram negative
coccobacillus

12. Introduction
•Gram negative bacillus
•Water and soil
•Associated with biofilms, antibiotics
•Survives on fomites surfaces for
weeks
•NOT PART OF NORMAL
HUMAN FLORA

13. Infection and Outbreaks
•Intensive care unit
•Health care settings
•Compromised immune
systems
•Colonised and infected
patients are point sources

14. Morphology
•Pleomorphic aerobic gram-negative bacillus
•Commonly isolated from the hospital environment
and hospitalised patients
•Rod-shaped during rapid growth and
coccobacillary in stationary phase
•Encapsulated
•Non-motile (although may exhibit twitching
motility)

15. Morphology
•Gram-negative
organisms
•Although retention of
crystal violet may result
in incorrect
identification as gram-
positive cocci

16. Biochemical reactions
•Oxidase negative
•Indole negative
•Catalase positive
•Aerobic bacteria

17. Colony characteristics
•Colonies are non-
pigmented, domed,
mucoid with smooth
surfaces
•The bacteria do not
reduce nitrate or to grow
anaerobically

18. Survival in natural environment
A. baumannii can survive for months
on: making nosocomial transmission
extremely difficult to control
•Clothing and bedclothes
•Bed rails
•Ventilators
•Sinks
•Door knobs

19. High risk individuals
•Hospitalization
•Significant co-morbidities
•Mechanical ventilation
•Cardio-respiratory failure
•Previous infection
•Antimicrobial therapy
•Urinary catheters

20. Carriers of infection
•Acinetobacter causes colonization more often
than infection
•It lives in or on the body without causing
illness like skin of a healthcare worker
•People who are colonised become carriers who
spread the bacteria to others

21. Respiratory route is prominent
route of entry
•Respiratory system in most common site for
Acinetobacter infection because of transient
pharyngeal colonisation of health persons and
high rate of tracheotomy colonisation
•Acinetobacter has been reported to cause
community acquired bronchiolitis and
tracheobronchitis in healthy children

22. Clinical features – Hospital
acquired Pneumonia
•Symptoms – dyspnoea (few patients have
symptoms since most are nonverbal and on
mechanical ventilation)
•Signs – fever, tachypnoea, increased or
purulent secretions, haemoptysis, rhonchi,
crackles, reduced breath sounds,
bronchospasm

23. Clinical features – Community
Acquired Pneumonia
•CAP is typically characterised by an abrupt
onset and rapid progression to respiratory
failure and hemodynamic instability
•Septic shock ensues in ~1/3 patients

24. Clinical features – Bloodstream
infection
•Frequent source – vascular catheters and
respiratory tract
•Less common source – wounds and urinary tract
•Risk factors for Acinetobacter BSI – intensive
care, mechanical ventilation, prior surgery, prior
use of broad spectrum antibiotics,
immunosuppression, trauma, burns, malignancy,
central venous catheters, invasive procedures,
prolonged hospital stay

25. Clinical features – Bloodstream
infection
•Fever
•Shaking chills (rigors)
•Disorientation
•Hypotension
•Respiratory failure
•Sepsis and septic shock

26. Clinical features – Skin, soft tissue
and bone infection
•May contaminate surgical and
traumatic wounds leading to
severe soft tissue infection
progressing to osteomyelitis
•Frequently with presence of
prosthetic material and extensive
debridement

28. Clinical features – Urinary Tract
Infection
•Urinary Tract can become
colonised readily with
Acinetobacter particularly
in the setting of
indwelling urinary
catheters

29. Clinical features – other infection
•Colonisation in contact lens wearers – ocular
infection include corneal ulcers,
endophthalmitis, periorbital cellulitis
•Acinetobacter sinusitis has been associated
with development of pneumonia
•Describe in patients undergoing peritoneal
dialysis with most common manifestation are
abdominal pain and cloudy dialysate

30. Acinetobacter baumannii: Antibiotic
Resistance and Identification Challenges

31. Drug Resistance and Antibiotics
• Generally Acinetobacter spp. are resistant to:
first-, second-, third- generation Cephalosporins,
Macrolides (erythromycin, azithromycin,
clarithromycin), and Penicillins
• Medications to which Acinetobacter spp. may
be sensitive to: meropenem, colistin, amikacin,
rifampin, minocycline, tigecycline and polymyxinB

32. Exponential Rise in Resistance
Acinetobacter spp.
have shown
extensive resistant
to most first-line
antibiotics: Number
of citations found
in PubMed
regarding
Acinetobacter and
AMR

33. Different Mechanism of Antibiotic
Resistance
• Aminoglycosides: modifying enzymes
• Altered penicillin-binding proteins and Cephalosporins:
produces AmpC-type cephalosporinases (ADCs). ADC hydrolyses
amino-penicillins and extended spectrum cephalosporins
• Broad-spectrum β-lactamases: class B metallo-beta-lactamases
(MBLs) which confer a high level of resistance
• Carbapenamases: altered porin channels and other outer
membrane proteins and natural occurring beta-lactamase in A.
baumannii

34. Challenges to Consider during
Identification
• Acinetobacter baumannii can be lactose or non-
lactose fermenters
• Some strains are motile positive in SIM test
(biochemical test)
• Acinetobacter baumannii are gram variable: in
logarithmic phase usually short gram-negative
rods but more coccoid in stationary phase

35. MultiDrug Resistant strains a
global concern
•MDR A.baumannii is an emerging problem
•First line treatment is with carbapenems
antibiotics but carbapenem resistance is
increasingly common
•Other treatment options include polymyxin,
tigecycline and aminoglycosides

37. Epidemiology
•Emerging as important global, pan-resistant
gram negative bacteria – nosocomial pathogen
•Clearly pathogenic when recovered from
blood and sterile body sites
•May cause nosocomial epidemics from
contaminated common sources: ventilation
equipment, catheters

38. Can Acinetobacter infect HCW
•Acinetobacter rarely cause serious infection in
healthy people and therefore pose minimal
threat to HCW or patients’ family members
•Pregnant HCW are not at increased risk from
this organism and can therefore care for
patients infected or colonised with
Acinetobacter baumannii

39. Why Acinetobacter baumannii is
problematic
a. A. baumannii important cause of nosocomial
infection in ICUs
b. Treatment difficult because multi-resistant
c. Colonised, infected patients point source of A.
baumannii infections in health care settings
d. Prolonged organism survival on environmental
surfaces in hospitals contributed to protracted
outbreaks

40. Active surveillance of culture
•Ventilator dependent/
tracheotomy patient
•Patients admitted from long
term care facilities with
endemic Acinetobacter
•Patients with previous history
of Acinetobacter infection

41. Standard precautions in caring
patients
•Contact precautions are
indicated. It should be maintained
for the duration of hospitalisation
or until negative cultures are
obtained
•Hand hygiene – hand washing
and using alcohol based hand
sanitizer

42. Acinetobacter spp. in Tanzania

43. Acinetobacter in Tanzania
• Masinde et al., (2009) investigated prevalence of UTI among
pregnant women at Bugando Medical Centre. Out of 247
recruits, 36 urine samples were positive and 16.7% (n=6/36) were
caused by Acinetobacter spp.
• Manyahi et al., (2014) investigated multi-drug resistant bacterial
pathogens causing surgical site infections at MNH. 15% of the
bacteria isolated were Acinetobacter baumannii which were
highly resistant to most of the antimicrobial agents (73% to
100%).
• Mushi et al., (2014) investigated 234 multi-drug resistant gram-
negative bacteria from pus, urine, blood, aspirate and sputum at
Bugando Medical Centre. 4.4% of the isolates were
Acinetobacter baumannii isolated from blood and pus.

44. Acinetobacter baumannii at MNH
• Kabanangi (2017) conducted a study investigating bacterial
causes and antibiotic susceptibility patterns of aerobic isolated
from burn wound infections in Dar es Salaam
• Of the 70 burn patients; 66 burn patients had positive growth
and 131 bacteria were isolated. The most frequent isolated
bacteria was 26% Pseudomonas aeruginosa (n=34) followed
by 22% Acinetobacter spp. (n=29)
• 86% resistant to aztreonam, 72% resistant to cotrimoxazole,
69% resistant to ceftazidime and ceftriaxone

45. Thank You