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Brazilian Journal of Infectious Diseases

Print version ISSN 1413-8670On-line version ISSN 1678-4391

Braz J Infect Dis vol.21 no.2 Salvador Mar./Apr. 2017 

Letters 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 

aUniversidade Federal de São Paulo (Unifesp), Laboratório Especial de Microbiologia Clínica (LEMC), São Paulo, SP, Brazil

bUniversidade Federal de São Paulo (Unifesp), Instituto de Oncologia Pediátrica, (IOP-GRAACC), São Paulo, SP, Brazil

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 bla SPM-1 M βL 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 M βL 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 M βL 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
1 2011/10/31 Low level of consciousness convulsion and hyponatremia No No 2011/11/26 Urine Discharge Positive B
2 2011/11/29 Tachypnea No No 2011/11/27 Blood Death Positive C2
3 2011/11/04 Hypervolemia and respiratory distress Yes Yes 2011/12/01 Urine Discharge Positive C5
4 2012/02/08 Gastrointestinal bleeding No Yes 2012/02/08 Blood Death Positive C3
5 2012/02/16 Fever and dyspnea Yes No 2012/02/16 Blood Death Positive C1
6 2012/01/30 Fever of unknown origin No No 2012/02/18 Blood Death Positive Not typeable
7 2012/02/18 Veno-occlusive disease and respiratory failure Yes Yes 2012/02/28 Blood Death Positive A1
8 2012/03/17 Septic shock No No 2012/03/27 Blood and catheter Death Positive C
9 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.


1 Mendes RE, Kiyota KA, Monteiro J, et al. Rapid detection and identification of metallo-beta-lactamase-encoding genes by multiplex real-time PCR assay and melt curve analysis. J Clin Microbiol. 2007;45:544-547. [ Links ]

2 Fernandes TA, Pereira CAP, Petrili AS, Pignatari ACC. Caracterização molecular de Pseudomonas aeruginosa resistentes a carbapenêmicos e produtoras de metalo- β-lactamase isoladas em hemoculturas de crianças e adolescentes com câncer. Rev Soc Bras Med Trop. 2000;43:372-376. [ Links ]

3 Silva FM, Carmo MS, Silbert S, Gales AC. SPM-1-producing Pseudomonas aeruginosa: analysis of the ancestor relationship using multilocus sequence typing, pulsed-field gel electrophoresis, and automated ribotyping. Microb Drug Resist. 2011;17:215-220. [ Links ]

Received: September 23, 2016; Accepted: October 29, 2016

*Corresponding author. E-mail address: (M.G. Quiles).

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