Pseudomonas-Infected Cystic Fibrosis Patient Sputum Inhibits the Bactericidal Activity of Normal Human Serum

Abstract

CYSTIC FIBROSIS 747 nebulizer). However, the adsorption rate in Figure 2C is still more rapid than that of vorkxed CLL dispersions in Figure 1 for the uniform fmal dispersion concentration (5 mg CLL/71 ml subphase) used (see "Materials and Methods"). This dilute concentration was chosen because it allow a disaimination between the adsorption isotherms of CLL (Si) and CLL (V). At h@m concentdona (z 0.25 mg/ml) vortexed CLL dqcrsions adsorb as rapidly as ch u m i d dispersions in Figure 2 SummpryChronic obstructive vulmonarv infection is the maior cause of Sputum samples were obtpined from nkteen cystic fibrosis (CF) patients with respiratory tract infectiom due to Reuhnonm rrmrginasa and were exrmined for the presence of a specific local protective or blacking fador, which might partrally explain the inability of CF patients' pulmonary defense mechanisms to clear their lungs of Reudomonm infection. Using an assay that measures the bactericidal activity of fresh nonnd human sernm (FHS), eight-of nineteen CF sputa examined were capable of protecting either autdogous or heterdogous strains of P. uenrgtmccr from serum bactericidal activity. Most of this protective activity was absorbable at 4OC by P s e r r d o m , and could be reduced by dilution In phosphate buffered sdim or counteracted by an i~-crease in senun concentration. This protective activity is believed to be due to a Reudomomq-specific bactericidal blocking antibody. In contrast, only two of 17 non-CF sputa were found to significantly inbibit the bactericidal activity of FHS for P. aeruginosa Furthermore, three out of five CF sputa also protected Escherichiu eoh' from the bactericidal activity of FHS. This protective activity was mucb less tbrn that observed with P. aerughosu, and was not absorbable at 4"C, suggesting the presence of a second blocking or protective factor in CF sputum. From these observatioos, we conclude that sputum from CF patients infected with P. aerughoaa contains one or more factors that interfere with the bactericidal activity present in FHS.Abbreviations BHI, brain heart infusion CF, cystic fibrosis CFU, colony fonning unit FHS, fresh normal human serum PBS, plumphate buffered saline PIA, pseudomonas isolation agar sIgA, secretory IgA morbidity and mortaliiy in people with cystic fibroiis (CF). Although respiratory infection with Staphylococcur aureus often occurs, ~se;domo&s aetuginosa ( p~i & r l y the mucoid colonial form) eventually emerges as the dominant pathogen in 70-905b of CF patients, and > 90% die of progressive pulmonary insufftciency complicated by infection with P. aenrginosa (4).Except for respiratory tract infections, CF children are not more susceptible to infection than normal children of comparable age. P. aenrginosa is known to be an opportunistic pathogen, which commonly infects the debilitated patient (25,26), and is seldom isolated from pediatric patients with chronic respiratory disease other than CF (4, 11). These basic clinical observations, coupled with the fact that pulmonary infections rarely spread...

Host Defenses in Patients with Cystic Fibrosis: Modulation by <i>Pseudomonas aeruginos</i><i>a</i>

“…Another inhibitory factor has been found recently in CF sputum [100]. This substance interferes with the bactericidal activity of serum against both homologous and heterologous strains of P. aeruginosa, is absorbed by Pseudomonas and is thought to be an antibody [100]. Fu ture studies should be conducted to ascertain the nature of these blocking substances in CF serum and sputum and to determine if they are the same as the F(ab'h blocking factor described by Fick et al [98] and Fick and Reynolds [99] that interferes with phagocyto sis of Pseudomonas by macrophages.…”

“…This factor is in the IgG serum fraction and is not removed by absorption with the patient's Pseudomonas strain [37]. Another inhibitory factor has been found recently in CF sputum [100]. This substance interferes with the bactericidal activity of serum against both homologous and heterologous strains of P. aeruginosa, is absorbed by Pseudomonas and is thought to be an antibody [100].…”

Biofilm formation and serum susceptibility in Pseudomonas aeruginosa

“…The host innate immune system includes serum components, such as antibodies and proteins of the complement system that mediate the bactericidal effect of serum. This phenomenon is seen with a higher frequency of serum resistance among P. aeruginosa strains isolated from blood, wounds, urine [7,8] than among strains isolated from the sputum of asymptomatic patients with cystic fibrosis [9][10][11]. Serum resistance might be an important microbial phenotype, which could conceivably differentiate between invasive and non-invasive strains and isolates [12].…”

The formation of microbial exoskeletons is driven by a controlled calcium-concentrating subcellular niche

“…Patient's samples: Sputum was collected from adult patients as published previously (4) and stored in 4ºC degrees to allow microscopy. All patients positive for calcite were carrying chronic pseudomonas infections.…”