The Brazilian Journal of Infectious Diseases The Brazilian Journal of Infectious Diseases
Braz J Infect Dis 2017;21:205-6 - Vol. 21 Num.2 DOI: 10.1016/j.bjid.2016.10.012
Letter to the Editor
High mortality outbreak of carbapenem-resistant Pseudomonas aeruginosa infection in a Brazilian pediatric oncology hospital
Milene Gonçalves Quilesa,, , Fabianne Carlesseb, Maria Aparecida Aguiar da Silvab, Roberta Cabral Mingronea, Juliane Melo Fonsecaa, Dafne Cardoso Silvab, Antonio Carlos Campos Pignataria
a Universidade Federal de São Paulo (Unifesp), Laboratório Especial de Microbiologia Clínica (LEMC), São Paulo, SP, Brazil
b Universidade Federal de São Paulo (Unifesp), Instituto de Oncologia Pediátrica, (IOP-GRAACC), São Paulo, SP, Brazil
Received 23 September 2016, Accepted 29 October 2016
Dear Editor,

Carbapenem-resistant Pseudomonas aeruginosa is an important nosocomial pathogen associated with high mortality rates and can persist in moist environments in hospitals. Several outbreaks have been associated with environmental contamination, contaminated medical equipment, and healthcare cross-transmission. The production of acquired metallo-β-lactamase SPM-1 has been frequently associated to these infections.

Here, we report an outbreak of carbapenem-resistant P. aeruginosa encoding the blaSPM-1 MβL gene affecting nine patients under cancer treatment admitted at the Institute of Pediatric Oncology from November 2011 to May 2012. Strains were isolated from blood (n=7) and urine (n=2) and identified by BD Phoenix™ Automated System (BD Biosciences, Sparks Md). DNA was extracted using the QIAamp DNA mini-kit (QIAGEN, CA) and tested for MβL genes by Multiplex real-time PCR (Rotor-gene-Q, Qiagen, CA)1 followed by DNA sequencing (ABI sequencer, Applied Biosystems, USA). Clonal relatedness was evaluated by pulsed field gel electrophoresis (PFGE) using the SpeI restriction endonuclease (New England BioLabs, USA). The band patterns were analyzed using the Bionumerics Software 7.6 (Applied Maths, Belgium).

All nine P. aeruginosa isolates were resistant to all beta-lactams, fluoroquinolones, and aminoglycosides but susceptible to colistin. The samples were positive for the blaSPM-1 and negative for other MβL genes. PFGE demonstrated three different clusters, one of them was highly related to the endemic clone SPM-1 previously reported in the institution.2 This fact reinforces that a genomic variety recently observed among various SPM-1-producing P. aeruginosa isolates is result of the accumulation of mutations along the time and the endemic clone was now adapted to spread in-hospital ambient.3

Three patients were previously colonized by P. aeruginosa and one had a contaminated prosthesis before the infection episode. Out of the nine patients, those who had the strain isolated from blood died (Table 1). All affected patients were critically ill and neutropenic. The majority of them presented septic shock and acute respiratory syndrome. Thus, we think these factors, combined with the lack of therapeutic options for these infections, could explain the observed high mortality rate.

Table 1.

Clinical data of infection episodes caused by SPM-1 producing Pseudomonas aeruginosa.

Patient  Intensive care unit admission date  Diagnosis  Hemodialysis  Previously colonization by Pseudomonas aeruginosa  Date of positive isolation of Pseudomonas aeruginosa  Site of bacteria isolation  Death/discharge  Real-time PCR for blaSPM gene  PFGE pattern 
2011/10/31  Low level of consciousness convulsion and hyponatremia  No  No  2011/11/26  Urine  Discharge  Positive 
2011/11/29  Tachypnea  No  No  2011/11/27  Blood  Death  Positive  C2 
2011/11/04  Hypervolemia and respiratory distress  Yes  Yes  2011/12/01  Urine  Discharge  Positive  C5 
2012/02/08  Gastrointestinal bleeding  No  Yes  2012/02/08  Blood  Death  Positive  C3 
2012/02/16  Fever and dyspnea  Yes  No  2012/02/16  Blood  Death  Positive  C1 
2012/01/30  Fever of unknown origin  No  No  2012/02/18  Blood  Death  Positive  Not typeable 
2012/02/18  Veno-occlusive disease and respiratory failure  Yes  Yes  2012/02/28  Blood  Death  Positive  A1 
2012/03/17  Septic shock  No  No  2012/03/27  Blood and catheter  Death  Positive 
2012/04/26  Respiratory distress  No  No  2012/05/01  Blood and catheter  Death  Positive  C4 

Although no common source could be identified, and given the limited therapeutic options for these infections, there is an urgent need for a better adherence of infection control practices in addition to investigate SPM-producing strains in routine diagnostic bacteriorology to prevent further dissemination of this challenging pathogen.

Conflicts of interest

The authors declare no conflicts of interest.

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Corresponding author.
Copyright © 2016. Sociedade Brasileira de Infectologia
Braz J Infect Dis 2017;21:205-6 - Vol. 21 Num.2 DOI: 10.1016/j.bjid.2016.10.012