The Scientific World Journal Volume 2012, Article ID 617218, 7 pages doi:10.1100/2012/617218 The cientificWorldJOURNAL Research Article Upper Respiratory Tract Colonization by Gram-Negative Rods in Patients with Chronic Lymphocytic Leukemia: Analysis of Risk Factors Izabela Korona-Glowniak, 1 Ewelina Grywalska, 2 Beata Chudzik, 1 Agnieszka Bojarska-Junak, 2 Anna Malm, 1 and Jacek Rolinski 2 1 Department of Pharmaceutical Microbiology, Medical University of Lublin, 20-093 Lublin, Poland 2 Department of Clinical Immunology, Medical University of Lublin, 20-093 Lublin, Poland Correspondence should be addressed to Izabela Korona-Glowniak, iza.glowniak@umlub.pl Received 31 October 2011; Accepted 13 December 2011 Academic Editor: Ada Funaro Copyright © 2012 Izabela Korona-Glowniak et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The aim of the study was to assess the frequency and predisposing factors of colonization of upper respiratory tract by Gram- negative rods (GNRs) in chronic lymphocytic leukemia (CLL) patients. Antimicrobial susceptibility of the isolated strains was determined. A significantly higher frequency of GNR colonization in CLL patients was observed (36.7%) in comparison to healthy volunteers (8.3%). GNR isolates mainly belonged to the Enterobacteriaceae family. Three isolates of GNR demonstrating presence of AmpC β-lactamases and one ESBL-producing strain were obtained from CLL patients. GNR colonization rate was higher among CLL patients with lower level of IgG in serum (P = 0.017), with higher number of neutrophils (P = 0.039) or higher number of lymphocytes in serum (P = 0.053). The longer the time elapsed since diagnosis, the higher the frequency of GNR colonization observed. Multivariate analysis showed importance of the Rai stage, number, and type of infections as independent predictors of GNR colonization in CLL patients. 1. Introduction Infectious complications are still one of the major causes of morbidity and mortality in patients with chronic lympho- cytic leukemia (CLL). Infections affect mainly the respiratory tract, skin, or urinary tract. The most common respiratory infections are acute and chronic sinusitis, otitis media, and pneumonia. In the past pneumonia was caused mainly by Streptococcus pneumoniae, but with current chemotherapeu- tic regimens, the spectrum of pathogens includes Gram-neg- ative rods (GNR), Nocardia species, Legionella species, and Pneumocystis carinii [1]. An increase in infections caused by GNR, particularly bacteremia and pneumonia, may reflect more advanced disease and profound myelosuppression in these patients [2]. The epithelial surfaces of the upper respiratory tract are continuously exposed to a wide variety of commensal and potentially pathogenic microorganisms, but the density and composition of colonization need to be controlled by the host [3]. In addition to acting as a physical barrier, epi- thelial cells respond to specific microbial products with the generation of signals, such as cytokines, that trigger inflammation. Colonization of the upper respiratory tract by pathogens is often the first step in a multifactorial process leading to disease. About 80% of CLL patients will sustain infectious complications during their disease, and 50–60% of patients will die due to infection [4]. The major risk factors for infection in these patients are immune defects that are inherent to the primary disease process and therapy-related immunosuppression. Refractory CLL patients subjected to allogenic hematopoietic cell trans plantation (allo-HCT) also have a particularly high incidence of infections compared to allo-HCT recipients with other lymphoid malignancies [5, 6] Disease- and therapy-related immune defects include hypogammaglo bulinemia, as well as perturbations in cell-mediated