In the last decade, many emerging multidrug resistant pathogens have been described in CF patients including new species of the
Burkholderia cepacia complex,
Brevundimonas diminuta,
Inquilinus limosus,
Acetobacter indonesiensis,
Achromobacter xylosoxidans,
Ochrobactrum anthropi, and bacteria of the genus
Pandoraea [
17,
18]. The pathogenicity of
Pandoraea species remains controversial. These bacteria have been occasionally recovered from the lung transplant and/or respiratory tract of CF patients, as well as from blood cultures in non-CF patients and environmental samples [
2,
4,
8,
19]. In our review of the bibliography, we found few cases of CF patients chronically colonized with
P. sputorum: one case from Australia [
8], two cases from Spain [
10,
11], and one case from France [
5]. Interestingly, in our CF patient,
S. aureus and
P. aeruginosa were eventually isolated from respiratory tract cultures together with
P. sputorum. This situation makes more difficult to know the real contribution of
P. sputorum to the clinical condition of our patient. In this regard, intermittent or persistent colonization with
Pandoraea species, that sometimes coincides with a deterioration in lung function, has been reported in addition to clinical evidence of invasive potential [
8,
10,
11,
18]. Furthermore, besides the inability of
Pandoraea species to produce a biofilm in the respiratory tract [
20], it remains still unclear the role of different virulence factors, mechanisms of pathogenicity, the possibility of transmission between patients, and their role in lung damage in CF patients. This situation emphasizes the importance of having more data about clinical cases. The
Pandoraea genus is multidrug resistant and treatment may be problematic. In our case,
P. sputorum was only susceptible to imipenem and TMS, with a low MIC for imipenem (≤0,25 mg/L), and although the treatment failed to eradicate the bacteria, the clinical condition improved. This pattern of being resistant to carbapenem and meropenem but sensitive to imipenem, appears to be unique to most
Pandoraea genus [
5,
21], and it can be a practical guideline in the earliest identification steps.
It is documented, when applying only conventional identification phenotypic methods, the microbiology laboratory commonly misidentifies this pathogen as
Ralstonia,
Stenotrophomonas or
Burkholderia species [
6‐
8]. It has been also noted the limitations of the sequences of 16S rRNA and
gyrB genes for differentiating the
Pandoraea species [
8,
22]. The accuracy and usefulness of MALDI-TOF as a routine technique for rapid identification of bacterium was demostrated. Nevertheless, one factor limiting the use of MALDITOF MS is the scant reference data sets for microorganisms that are infrequently isolated from clinical specimens [
10]. Due to these limitations, a polyphasic approach for an accurate identification is recommended. In our CF patient, all isolates were identified as
P. sputorum, combining 16S rRNA PCR and sequencing, and a MALDI-TOF MS proteomic platform. Lastly, to determine persistence over time of the same
P. sputorum isolate, as generally occurs with
P. aeruginosa and Bcc in CF patients, a molecular epidemiological analysis was performed [
2,
23]. BOX-PCR and ERIC-PCR showed indistinguishable patterns among all isolates of
P. sputorum (includeding last isolate collected in April 2016), indicating a possible chronic colonization, which is defined here as three positive cultures of the same strain isolated within a 6-month period.