PMN-dominated airway inflammation is a major component of cystic fibrosis (CF) lung disease. Epithelial cells respond to organisms such as Pseudomonas aeruginosa, the major pathogen in CF, by expressing the leukocyte chemokine IL-8. Experiments were performed using several different types of respiratory epithelial cells that demonstrate that ligation of ceramide-associated receptors on epithelial surfaces by P. aeruginosa pili is a major stimulus for the translocation of transcription factor nuclear factor (

, three novel alpha-helical peptides derived from SMAP29 and termed ovispirins (OV-1, OV-2, and OV-3), and two derivatives of CAP18 were tested by broth microdilution assays. Their MICs were determined for multiply antibiotic-resistant Pseudomonas aeruginosa (n ‫؍‬ 24), Burkholderia cepacia (n ‫؍‬ 5), Achromobacter xylosoxidans (n ‫؍‬ 5), and Stenotrophomonas maltophilia (n ‫؍‬ 5) strains isolated from CF patients. SMAP29 was most active and inhibited mucoid and nonmucoid P. aeruginosa strains (MIC, 0.06 to 8 g/ml). OV-1, OV-2, and OV-3 were nearly as active (MIC, 0.03 to 16 g/ml), but CAP18 (MIC, 1.0 to 32 g/ml), CAP18-18 (MIC, 1.0 to >32 g/ml), and CAP18-22 (MIC, 0.5 to 32 g/ml) had variable activities. LL37, mCRAMP, and rCRAMP were least active against the clinical isolates studied (MIC, 1.0 to >32 g/ml). Peptides had modest activities against S. maltophilia and A. xylosoxidans (MIC range, 1.0 to > 32 g/ml), but none inhibited B. cepacia. However, CF sputum inhibited the activity of SMAP29 substantially. The effects of peptides on bacterial cell membranes and eukaryotic cells were examined by scanning electron microscopy and by measuring transepithelial cell resistance, respectively. SMAP29 caused the appearance of bacterial membrane blebs within 1 min, killed P. aeruginosa within 1 h, and caused a dose-dependent, reversible decrease in transepithelial resistance within 5 h. The tested cathelicidin-derived peptides represent a novel class of antimicrobial agents and warrant further development as prophylactic or therapeutic agents for CF lung disease.

In the past decade, potential pathogens, including Alcaligenes species, have been increasingly recovered from cystic fibrosis (CF) patients. Accurate identification of multiply antibiotic-resistant gram-negative bacilli is critical to understanding the epidemiology and clinical implications of emerging pathogens in CF. We examined the frequency of correct identification of Alcaligenes spp. by microbiology laboratories affiliated with American CF patient care centers. Selective media, an exotoxin A probe for Pseudomonas aeruginosa, and a commercial identification assay, API 20 NE, were used for identification. The activity of antimicrobial agents against these clinical isolates was determined. A total of 106 strains from 78 patients from 49 CF centers in 22 states were studied. Most (89%) were correctly identified by the referring laboratories as Alcaligenes xylosoxidans. However, 12 (11%) strains were misidentified; these were found to be P. aeruginosa (n ‫؍‬ 10), Stenotrophomonas maltophilia (n ‫؍‬ 1), and Burkholderia cepacia (n ‫؍‬ 1). Minocycline, imipenem, meropenem, piperacillin, and piperacillin-tazobactam were the most active since 51, 59, 51, 50, and 55% of strains, respectively, were inhibited. High concentrations of colistin (100 and 200 g/ml) inhibited 92% of strains. Chloramphenicol paired with minocycline and ciprofloxacin paired with either imipenem or meropenem were the most active combinations and inhibited 40 and 32%, respectively, of strains. Selective media and biochemical identification proved to be useful strategies for distinguishing A. xylosoxidans from other CF pathogens. Standards for processing CF specimens should be developed, and the optimal method for antimicrobial susceptibility testing of A. xylosoxidans should be determined.Cystic fibrosis (CF) is the most common life-shortening disease caused by a recessive autosomal gene in the Caucasian population and afflicts about 60,000 patients worldwide, approximately 30,000 of whom are cared for in the United States (21). While the genetic defect in CF is known, the relationship between abnormal CF transmembrane conductance regulator and chronic pulmonary disease is not yet fully understood (22). Chronic pulmonary disease is characterized by a vicious cycle of inflammation and infection and is the major cause of morbidity and mortality. The pathogens of CF are well characterized and include Staphylococcus aureus, nontypeable Haemophilus influenzae, Pseudomonas aeruginosa, and Burkholderia cepacia (10).During the past decade, several additional potential pathogens have been recovered from CF patients, including nontuberculous mycobacteria (19), Stenotrophomonas maltophilia (3), and Alcaligenes species, particularly Alcaligenes xylosoxidans (29). As reported to the U.S. Cystic Fibrosis Foundation's National Patient Registry in 1996 and 1997, 1.9 and 2.7% of all CF patients harbored Alcaligenes spp. (7,8). As determined by a research laboratory participating in a phase III trial of aerosolized tobramycin in CF patients who were Ն6 years of ...

Susceptibility (18 antimicrobial agents including high-dose tobramycin) and checkerboard synergy (23 combinations) studies were performed for 2,621 strains of Burkholderia cepacia complex isolated from 1,257 cystic fibrosis patients. Minocycline, meropenem, and ceftazidime were the most active, inhibiting 38%, 26%, and 23% of strains, respectively. Synergy was rarely noted (range, 1% to 15% of strains per antibiotic combination).

Stenotrophomonas maltophilia is a newly emerging pathogen being detected with increasing frequency in patients with cystic fibrosis (CF). The impact of this multidrug-resistant organism on lung function is uncertain. The optimal treatment for S. maltophilia in CF patients is unknown. We studied the in vitro activity of ten antimicrobial agents, and conducted synergy studies by using checkerboard dilutions of eight pairs of antimicrobial agents against strains isolated from 673 CF patients from 1996 to 2001. This represents approximately 7 to 23% of the CF patients in the United States who harbor S. maltophilia annually. Doxycycline was the most active agent and inhibited 80% of 673 initial patient isolates, while trimethoprim-sulfamethoxazole inhibited only 16%. High concentrations of colistin proved more active than high concentrations of tobramycin and gentamicin. Serial isolates (n ‫؍‬ 151) from individual patients over time (median, 290 days) showed minimal changes in resistance. Synergistic or additive activity was demonstrated by trimethoprimsulfamethoxazole paired with ticarcillin-clavulanate (65% of strains), ciprofloxacin paired with ticarcillinclavulanate (64% of strains), ciprofloxacin paired with piperacillin-tazobactam (59% of strains), trimethoprimsulfamethoxazole paired with piperacillin-tazobactam (55% of strains), and doxycycline paired with ticarcillinclavulanate (49% of strains). In all, 522 (78%) isolates were multidrug resistant (i.e., resistant to all agents in two or more antimicrobial classes) but 473 (91%) of these were inhibited by at least one antimicrobial combination (median, four; range, one to eight). To determine appropriate treatment for patients with CF, it is important to monitor the prevalence, antimicrobial susceptibility, and clinical impact of S. maltophilia in this patient population.