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Indian Pediatr 2011;48: 723-725 |
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Outbreak of Sphingomonas paucimobilis
Septicemia in a Neonatal Intensive Care Unit |
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Mehmet Mutlu, *Gülçin Bayramoglu, †Gürdal Yilmaz,
Berna Saygin and Yakup Aslan
From the Departments of Pediatrics, *Microbiology and
Clinical Microbiology, and †Infection
Diseases, Karadeniz Technical University, Trabzon, Turkey.
Correspondence to: Dr Mehmet Mutlu, Kalkinma Mah. Farabi
Hastanesi, Department of Pediatrics, Karadeniz Technical University,
Trabzon, Turkey.
Email:
[email protected]
Received: October 25, 2010;
Initial review: December 2, 2010;
Accepted: December 22, 2010.
PII:S09747559INPE1000369-2
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Abstract
We describe an outbreak of Sphingomonas
paucimobilis in 13 newborn infants with septicemia and septic
shock. Fifteen available isolates were obtained from patients and
distilled water. Pulsed-field gel electrophoresis showed that there was
a cross-transmission of S. paucimobilis in eleven patients but
these types were not the same the isolate obtained from the distilled
water. The outbreak was terminated by taking appropriate control
measures for infection and change of source of distilled water.
Key words: Neonate, Outbreak, Sepsis, Sphingomonas
paucimobilis, Turkey.
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Sphingomonas paucimobilis is an aerobic, weakly oxidase-positive,
catalase-positive, motile, glucose non-fermenting and gram-negative rod.
This microorganism has been isolated from the hospital water systems,
mechanical ventilators, soil, and different clinical specimens [1]. S.
paucimobilis can cause nosocomial and community-acquired infections
[1,2]. Although nosocomial outbreaks of S. paucimobilis bacteremia
have been reported in pediatric wards [3], it has rarely been reported in
neonatal intensive care unit (NICU) [4].
We report an outbreak of septicemia caused by S.
paucimobilis in 13 neonates in a NICU.
Methods
Medical charts of all the newborns having a blood
culture positive for S. paucimobilis were reviewed for the
following factors: birthweight; gestational age; delivery type;
gender; postnatal age at time of admission to the NICU; sepsis related
death; exposure to antimicrobial agents; receiving total parental
nutrition (TPN); histamine
2-blockers and steroids; staying in incubator; invasive and procedures
such as mechanical ventilation, central catheterization and operation.
Newborns with S. paucimobilis infection were included if they had
spent at least 48 hours in NICU before their positive cultures and
fulfilled the criteria for having sepsis and septic shock [5].
Cultures were obtained from the hands of healthcare
workers and environment of NICU to identify the source. All the
isolates were analyzed by pulsed-field gel
electrophoresis (PFGE) using XbaI endonuclease. PFGE patterns were
compared accor-ding to the criteria established by Tenover, et al.
[6].
To determine the potential risk factors for S.
paucimobilis septicemia, a matched case-control study was
performed by comparing each case of S. paucimobilis to two
uninfected controls and one case of extended-spectrum beta-lactamase-producing
Klebsiella pneumoniae blood stream infection. Controls were infants
who (a) were hospitalized in the NICU during the same period and
their cultures negative for epidemic strain, (b) had
been in the NICU for at least 48 hours during the outbreak, and (c)
had a primary diagnosis that was similar of the infants with S.
paucimobilis infections. We compared S. paucimobilis infections
with K. pneumoniae infection, because K. pneumoniae
is the most common GNR causative agent for nosocomial sepsis in our unit.
Results
Fifteen isolates of S. paucimobilis were
identified between October 7, 2008 and November 15, 2008. Two of them
(13.3%) were isolated from the distilled water, and 13 (86.7%) from the
blood sample of the newborn babies. Twelve neonates had sepsis and
one premature newborn had septic shock.
TABLE I Characteristics and Potential Risk Factors in Culture Postive and Uninfected Controls
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Characteristic |
Culture positive for |
Controls |
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S. paucimobilis (n=13) |
K. pneumoniae (n=13) |
(n=26) |
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Birthweight (g) |
2172±1003 |
2303±1112 |
2302±658 |
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Gestational age (wks) |
33.7±4.9 |
34.6±4.4 |
34.1±2.5 |
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Preterm labor, n (%) |
7 (54) |
7 (54) |
21 (81) |
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Males, n |
8 |
9 |
17 |
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Vaginal delivery, n (%) |
5 (38) |
6 (46) |
9 (35) |
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Prolonged rupture of membranes, n (%) |
3 (23) |
2 (15) |
1 (4) |
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Day of life positive culture |
32.8±30.4 |
25.2±17.7 |
- |
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Duration of receiving antibiotics* (d) |
9.9±8.7 |
8.9±5.6 |
- |
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Central venous cathetar, n (%) |
5 (38) |
8 (62)a |
3 (12)b |
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Duration of stay in incubator (d) |
32.8±30.4c |
11.8±11.5d |
5.8±10.5e |
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Exposure to postnatal steroids |
3 (23) |
3 (23) |
2 (8) |
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Duration of indwelling central line* (d) |
5.5±8.7f |
6.2±6.1g |
0.8±2.2h |
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Duration of mechanical ventilation (d) |
15.6±23.9ý |
6.5±10.4i |
0.5±1.7j |
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Surgery, n (%) |
2 (15) |
1 (8) |
1 (4) |
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Duration of TPN (d) |
18.8±26.4k |
14.8±11.2l |
2.4±5.7m |
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Treatment with H2-blokers, n (%) |
6 (46) |
10 (77)n |
5 (19)o |
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Death, n (%) |
1 (8) |
4 (31)ö |
0 (0)p |
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* Prior to onset of
infection; P<0.05: c-d, ý-j, i-j; P<0.005: a-b, f-h, g-h, k-m, l-m,
ö-p; P<0.001: c-e, n-o. |
Patients with S. paucimobilis infections
had a longer stay in incubator (P=0.0001), were receiving TPN (P=0.002),
received mechanical ventilation (P=0.006), and had
more number of days with indwelling central line (P=0.035) than
controls. Patients with S. paucimobilis infection had longer
stay in incubator than patients with K. pneumoniae infection (P<0.036).
We detected three major PFGE patterns (A-C) out of the
15 isolates tested. Nine of the thirteen patients’ isolates (pattern A)
were indistinguishable by PFGE while the two differed by two bands
(pattern A1). One other patient’s isolates were considered
epidemiologically unrelated to the outbreak (pattern B). Two patterns
(pattern C) were shared by the isolates from distilled water. One
patient’s blood isolate had identical antibiotype as outbreak isolates was
not available for PFGE testing. Molecular typing proved that there was a
cross-transmission of S. paucimobilis in eleven patients, but these
types were not the same the isolates from the distilled water. Healthcare
worker hand cultures were negative for this organism. S.
paucimobilis strains of the one dead patient were type A in PFGE
pattern. She died due to septic shock. No further cases were found during
a 20-month period.
Discussion
We report an outbreak caused by S. paucimobilis
during a 6-week period in a neonatal intensive care unit. Various
infections caused by S. paucimobilis include bacteremia, septic
shock, osteomyelitis, septic arthritis, endophthalmitis, myositis,
peritonitis, intravascular catheter-related bacteremia, biliary tract
infection, wound infection, urinary tract infection, ventilator-associated
pneumonia, pyoderma, neutropenic fever and gastrointestinal infection
have been reported previously [2,3,7-12].
In this study, we observed nosocomial sepsis in twelve
patients and septic shock in one patient. All neonates with
positive blood culture for S. paucimobilis infections had clinical
sepsis. Thus, growing of these micro-organisms in the blood cultures were
not accepted as contaminant.
Distilled water is used for the humidifying of
incubators and mechanical ventilators. It can be hypothesized that this
bacterium from distilled water may be a major source for S.
paucimobilis outbreaks. But S. paucimobilis types obtained from
distilled water were different from the types obtained from patients.
Major limitation of this study is source of the outbreak is not certain.
The outbreak was terminated within 3 months by intensified
infection-control measures.
Contributors: All authors contributed to concept
and design of the study. All authors were involved in drafting of the
manuscript and approved the final version.
Funding: Research Fund of Karadeniz Technical
University (Project number: 2007.114.001.8).
Competing interests: None stated.
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What This Study Adds?
• S. paucimobilis can cause sepsis and septic shock in
newborns, and outbreaks in NICU.
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