key: cord-0914785-kzdy7d16
authors: Poore, T. Spencer; Virella-Lowell, Isabel; Guimbellot, Jennifer S.
title: Potential Pathogenicity of Inqulinus limosus in a Pediatric Patient with Cystic Fibrosis
date: 2018-05-23
journal: Pediatric Pulmonology
DOI: 10.1002/ppul.24043
sha: 3dd177d3ce59cc01ba03764c465bb319a10d2786
doc_id: 914785
cord_uid: kzdy7d16

PRESENTATION: Patient is a 6-year-old male with CF, MRSA colonization, and pancreatic insufficiency that presented with worsening ppFEV1 and systemic symptoms despite multiple interventions. BAL grew NTM, Stenotrophomonas maltophilia, and Inquilinus limosus, a rare organism found in patients with CF. COURSE: I. limosus treatment was deferred. Despite treatment of other pathogens, symptoms worsened. I. limosus was targeted with meropenem, amikacin, and ciprofloxacin along with clindamycin for MRSA colonization. Within weeks, symptoms had resolved with ppFEV1 improvement. DISCUSSION: This case discusses the importance of a rare organism in the CF population. Targeting I.limosus was key to recovery, revealing its potential pathogenicity.

Inquilinus limosus is an aerobic Gram-negative rod that has been predominately cultured from patients with cystic fibrosis (CF). It is thought to be a soil bacterium, but little is known about its habitat, reservoir, and transmission. [1] [2] [3] [4] [5] This organism is often mis-identified as Pseudomonas aeruginosa (PA) and is difficult to treat given extensive resistance patterns.

I. limosus' pathogenicity is poorly understood. Multiple reports identified the organism by culture and 16S rDNA sequencing, yet its relevance remains uncertain given reports ranging from deterioration associated with isolation, to no clinical impact. Here, we describe a pediatric patient with isolation of abundant I. limosus in concert with non-tuberculous mycobacterium (NTM) and more common pathogens. The patient's symptoms were severe and progressive, only resolving with a treatment regimen optimized against I. limosus.

The patient is a 6-year-old male with CF (N1303 K/2490 + G > A) and pancreatic insufficiency that presented with chest pain and fever. The wileyonlinelibrary.com/journal/ppul declined from baseline of 87% to 65%, prompting admission. Bronchoscopy/bronchoalveolar lavage (BAL) was performed. Rare non-tuberculous mycobacteria (NTM) was isolated for the first time, along with S. maltophilia, and a new gram-negative rod that was sent to the CDC for identification. This was ultimately identified as I. limosus and was not treated, as its symptomatic role was unclear. The patient's antibiotic regimen was changed to piperacillin-tazobactam, ceftaroline, and voriconazole to better cover chronic colonization of MRSA and previous pathogens. He was treated for 14 days with a ppFEV1 improvement to 90%, but continued to have symptoms above his baseline.

Two weeks later, the patient had some improvement; however, his fatigue, cough, and weight loss persisted while his ppFEV1 decreased to 83%. There was concern that the treatment for his previous Aspergillus was inadequate, so voriconazole was resumed and he was to return to clinic 2 weeks later. illness began prior to isolation, it is possible I. limosus was contributing earlier given difficulty with identification and published evidence of immune response to Inquilinus prior to culture growth. 4 We cannot fully rule out the influence of MRSA or MAC on this patient's course.

Notably, he never isolated MRSA from his lower airway during this period and had no first-line treatment directed toward MAC until after improvement from a prolonged course targeting I. limosus.

This case of a young CF patient with multiple sources of infection demonstrates the complexity of CF exacerbations and supports the notion that I. limosus is an emerging pathogen. The patient's clinical course demonstrated the need for antibiotic coverage of I. limosus and reinforces its potential pathogenicity when developing treatment plans.

Clinical and microbiological features of Inquilinus sp. isolates from five patients with cystic fibrosis

Identification of Inquilinus limosus in cystic fibrosis: a first report in Italy

Inquilinus limosus in pulmonary disease: case report and review of the literature

Clonal analysis of Inquilinus limosus isolates from six cystic fibrosis patients and specific serum antibody response

Inquilinus ginsengisoli sp. nov., isolated from soil of a ginseng field

How to cite this article: Poore TS, Virella-Lowell I, Guimbellot JS. Potential pathogenicity of Inquilinus limosus in a pediatric patient with cystic fibrosis

David W. Kimberlin, MD, served as an infectious disease consultant in the case described in this manuscript, and kindly provided editorial suggestions. The authors are grateful to Ikea Moore, MT(AAB), ASCP for critical technical assistance with microbiologic studies.

All authors declare no conflicts of interest.