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Indian Pediatr 2011;48: 964-966 |
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Ventilator-associated Acinetobacter
baumannii Pneumonia |
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Kala Ebenezer, Ebor Jacob G James, Joy Sarojini Michael$,
Gagandeep Kang$ and Valsan Philip Verghese*
From the Pediatric ICU, and *Pediatric Infectious
Diseases, Department of Child Health; and $Department
of Microbiology and Hospital Infection Control Committee, Christian
Medical College and Hospital, Vellore, India.
Correspondence to: Dr Kala Ebenezer, Pediatric Intensive
Care Unit, Christian Medical College and Hospital,
Vellore, India 632 004.
Email: [email protected]
Received: August 24, 2010;
Initial review: October 13, 2010;
Accepted: February 28, 2011.
Published online: 2011 May 30.
PII: S09747559INPE1000201-2
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Abstract
We report an outbreak of ventilator-associated
pneumonia caused by carbapenem-resistant Acinetobacter baumannii
in 6 infants with acute lower respiratory tract infection. Non-bronchoscopic
bronchoalveolar lavage isolated A. baumannii in all these
infants. Environmental microbiological survey of the Pediatric intensive
care unit and pediatric wards identified oxygen humidifying chambers as
the source of Acinetobacter. Practices of cleaning and changing
of the humidifiers were reviewed and the outbreak was controlled with
new recommendations.
Key words:Acinetobacter, Nosocomial infection, Pneumonia,
Ventilator-associated.
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T
he incidence of
ventilator-associated
pneumonia (VAP) in pediatric patients
varies from 5.1%-33.3% [1-3]. Acinetobacter has emerged as a common causative agent of nosocomial
infections, particularly VAP [4-6]. Originally thought to be low-grade
pathogen contaminating the hospital environment, with its inherent ability
to survive in diverse reservoirs and develop resistance to disinfectants
and antimicrobials, it has transformed into an emerging, multidrug-resistant
nosocomial pathogen [7].
We report an outbreak, subsequent identification of
source and control of VAP caused by carbapenem-resistant Acinetobacter
baumannii in 6 infants admitted to the pediatric intensive care unit (PICU).
Methods
The outbreak occurred between 18th September to 10 th
October 2008 at the PICU, which annually admits over 1200 children up to
15 years of age. Blood cultures are obtained before initiation of
antibiotic therapy. Non-bronchoscope bronchoal-veolar lavage (NB-BAL) is
done if secondary lung infection is suspected, the indications being
secondary fever with or without elevated white cell count and/or
C-reactive protein (CRP), new or worsening findings on the chest X-ray,
purulent endotracheal secretions and increasing oxygen or ventilatory
requirement.
After isolating A. baumanni from clinical
specimens, a microbiologic survey for possible sources was done. Water
samples from oxygen humi-difying chambers, ventilator humidifiers,
thermo-meter solution and swabs from ventilator tubing, suction devices,
and other surfaces were sent for culture.
Isolates were identified biochemically and
antimicrobial susceptibility testing (AST) was done as per Clinical and
Laboratory Standards Institute (CLSI) guidelines [8].Colony forming units
per ml (cfu/mL) were calculated and reported.
Results
During the study period there were 73 admissions to
PICU with 43(59%) children receiving ventilatory support. Six isolates
from NB-BAL grew Acinetobacter baumannii. Relevant clinical
findings of the six infants (mean age 4.5 months) with ventilator-
associated A. baumannii pneumonia are shown in Table I.
All six received supplemental oxygen, nebulized terbutaline, intravenous
fluids and antibiotics; five received parenteral steroids. Initial
antibiotic therapy included penicillins and aminoglycosides followed by
cefotaxime in four infants, vancomycin in two and meropenem in four.
TABLE I Clinical Findings of Six Infants with Ventilator-associated A.Baumannii Pneumonia
|
Pt |
Diagnosis at |
Place |
Day and place |
Extubation |
Reintu- |
Day NB- |
No of |
Outcome |
|
No |
admission |
admitted |
of first intubation |
|
bation |
BALdone |
hospital days |
|
|
1 |
Bronchiolitis ASD |
ICU# |
Ward, 21 d |
No |
|
Day 22 |
25 |
Discharged |
|
2 |
Bronchiolitis |
ICU |
ICU, 36 h |
No |
|
Day 8 |
10 |
Discharged* |
|
3 |
WALRI, PDA |
ward |
ICU, 7d |
No |
|
Day 8 |
10 |
Discharged* |
|
4 |
Pneumonia |
ward |
ICU, 44h |
6 d |
8 d |
Day 6 |
8 |
Died |
|
5 |
WALRI, PFO |
ward |
Ward, 4 d |
6 d |
6 d |
Day 8 |
21 |
Discharged |
|
6 |
WALRI |
ICU |
arrived intubated |
4 d |
7 d |
Day 10 |
12 |
Discharged* |
|
WALRI: wheeze associated lower respiratory tract infection; ASD:
atrial septal defect; PDA: patent ductus arteriosus: PFO: patent
foramen ovale; ICU: intensive care unit; *discharged at parental
request; # transferred to ward day 5, readmitted to ICU;
BAL: Bronchoaleolar lavage. |
Three infants were directly admitted to PICU. While one
of them had arrived intubated the other was intubated at 36 hours in PICU
for respiratory failure. The third infant improved and was transferred out
on 5th hospital day. She however deteriorated on the 21 st
day with respiratory arrest, requiring cardiopulmonary resuscitation (CPR)
and readmission to PICU.
Among those who were initially admitted to the ward,
one was intubated there for apnea and cyanosis on the fourth day and
subsequently transferred into PICU. The other two infants were transferred
to PICU at 44 hours and seventh day for respiratory failure and intubated
shortly thereafter.
Three infants remained on ventilatory support
throughout their hospital stay. Even the three who were extubated
following apparent successful weaning, were subsequently reintubated after
a mean 49 hours (range 10-69 hours) for progressively increasing work of
breathing and fatigue.
NB- BAL done after a mean 10.3 days (range 6-22) of
hospitalization isolated multidrug-resistant A. baumannii (>10 4
cfu/mL) in all six infants. X-rays repeated simultaneously
showed significant worsening of existing infiltrates in all and evidence
of pneumonia in areas not previously affected in four. Of two infants
treated with colistin one survived. While one infant died in the hospital,
4 were taken home terminally ill by the family.
Seven of the 12 water samples from the oxygen
humidifying chambers from the ward and the ICU grew A. baumannii.
Cultures taken from other sites did not isolate Acinetobacter. The
A. bauminii isolates from patients and humidifiers were similar
(sensitive to colistin, and resistant to gentamicin, amikacin, cefotaxime,
ceftazidime, imipenem, meropenem, and aztreonam).
Review of existing cleaning and maintenance of
respiratory equipments practices revealed them to be suboptimal. New
recommendations were made as follows: (i) daily cleaning by rinsing
first with soap solution and then plain water, (ii) air/sun drying
daily; (iii) disinfection weekly, soaking the humidifying chamber
in freshly prepared 1% sodium hypochlorite solution for 10 minutes,
ensuring that the disinfectant completely covers and fills it, followed by
rinsing with distilled water and air/sun drying; and (iv) usage of
sterile water in the humidifier. The outbreak was controlled with these
new practices.
Discussion
Ventilator-associated, carbapenem-resistant Acineto-
bacter baumannii pneumonia was diagnosed in six infants based on
clinical and radiological findings supported by quantitative NB-BAL
cultures [9-11]. The infants had acute respiratory infections severe
enough to require ICU admission, intubation and ventilatory support. These
are exactly the known predisposing factors [7] for Acinetobacter, which
has emerged as a significant multidrug resistant patho-gen causing
nosocomial infections, VAP in particular [6-12] as well as line-related
infections in hospitalized oncology patients [14].
The outbreak of VAP with an organism unusual in our ICU
till then led us to an extended microbial surveillance that revealed the
same pathogen in oxygen humidifying chambers not just in the PICU but also
the wards, where children were admitted before and after ICU stay.
Nosocomial infection can negate the benefits of even
the best of medical care, underscoring the need for regular surveillance
for environmental contamination with multi-drug resistant organisms in the
hospital setting. Control of the outbreak of Acinetobacter
pneumonia with humidifier disinfection shows that simple measures of
infection control can help prevent hospital-acquired infections in the ICU
setting.
Contributors: All authors contributed to concept,
study design, data acquisition and drafting of the manuscript.
Funding: None.
Competing interests: None stated.
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