The pathogenesis and treatment of pulmonary infections in patients with cystic fibrosis

Reevaluating approaches to cystic fibrosis pulmonary exacerbations

Cystic Fibrosis (CF) lung disease is characterized by intermittent acute episodes of worsening signs, symptoms, and pulmonary function; these so-called pulmonary exacerbations (PEx) appear to be important drivers of long-term declines in lung function, quality of life, and life expectancy. Surveillance for development of PEx and their treatment is a fundamental component of chronic CF management, and the merits of novel CF therapies are often judged based on their ability to reduce the frequency of PEx. Given the central role that they play, it is surprising how poorly PEx are understood, how thin is the evidence base for their treatment and how often they are left unrecognized and untreated in clinical practice. This paper reviews what is known and what is unknown regarding the nature of PEx, and discusses the impact of missed recognition and treatment of these episodes as well as the apparent variation in practice across CF care centers. The arguments supporting a liberal, highly sensitive approach to the diagnosis of PEx are presented, as well as recommendation for how care programs can achieve consistency in their early recognition and treatment. A stepwise approach to personalized treatment supported by close follow-up to ensure the successful resolution of all signs and symptoms will lead to the stabilization of patients' lung function and quality of life. Recommendations are made regarding important priorities for research into evidence-based approaches to improving the care of PEx.

Optimization of anti-pseudomonal antibiotics for cystic fibrosis pulmonary exacerbations: III. fluoroquinolones

This review is the third installment in a comprehensive State of the Art series and aims to evaluate the use of fluoroquinolones in the management of P. aeruginosa infection in both children and adults with cystic fibrosis (CF). Oral and intravenous ciprofloxacin have been shown to be well-tolerated in the treatment of acute pulmonary exacerbations (APE) secondary to P. aeruginosa. Older literature supports an oral dosing regimen of 40 mg/kg/day divided every 12 hr, up to 2 g/day, and intravenous (IV) ciprofloxacin 30 mg/kg/day divided every 8 hr, maximum 1.2 g/day in children, and 750 mg administered orally twice a day or 400 mg IV every 8 hr in adults. However, a recent pharmacodynamic (PD) modeling study shows that the literature, U.S. Food and Drug Administration (FDA)-approved, and Cystic Fibrosis Foundation (CFF) guideline dosing regimens may be suboptimal for the treatment of P. aeruginosa in APE. Further study is warranted to determine if higher doses of ciprofloxacin are needed. Limited pharmacokinetic (PK), PK/PD, and efficacy studies involving levofloxacin exist in adult patients with CF. No pediatric data exists for levofloxacin in CF patients. Further study is needed to determine the tolerability and efficacy of levofloxacin in APE. At this time, the routine use of levofloxacin in the treatment of APE in pediatric and adult patients cannot be recommended.

Antibiotic use in Cystic Fibrosis

Chronic pulmonary infections contribute significantly to the morbidity and mortality of patients with CF. The primary pathogens are Pseudomonas aeruginosa (PA) and Staphylococcus aureus. Hemophilus influenzae has been isolated from a significant number of patients also. A number of the β-lactam and aminoglycoside antibiotics reportedly have altered pharmacokinetic variables in CF. Therapy of acute pulmonary deterioration consists of intravenous antibiotics for two weeks. Antibiotic selection is based on culture and sensitivity results. Currently, the combination of a broad-spectrum penicillin and an aminoglycoside seems to provide the best results. Prophylactic antibiotics are effective if the primary isolates are sensitive to the agents used. Chronic PA infections are problematic because effective oral agents are not available. Aerosolized antibiotics do not improve results over adequate systemic therapy for acute exacerbations. Questions regarding optimal dosages, frequency, and duration of therapy remain.

Respiratory virus infections in cystic fibrosis

Respiratory virus infections have pronounced and long-lasting effects on patients with cystic fibrosis (CF), resulting in significant declines in FVC, FEV(1) and Shwachman score, significantly increasing both the frequency and duration of hospitalisation. Deleterious effects on patients with CF have been reported for most viruses studied but the effects of respiratory syncytial virus and influenza appear the greatest. There is circumstantial evidence that respiratory virus infections may facilitate bacterial infections, particularly Pseudomonas aeruginosa.

Commonly used antibacterial and antifungal agents for hospitalised paediatric patients: implications for therapy with an emphasis on clinical pharmacokinetics

Due to normal growth and development, hospitalised paediatric patients with infection require unique consideration of immune function and drug disposition. Specifically, antibacterial and antifungal pharmacokinetics are influenced by volume of distribution, drug binding and elimination, which are a reflection of changing extracellular fluid volume, quantity and quality of plasma proteins, and renal and hepatic function. However, there is a paucity of data in paediatric patients addressing these issues and many empiric treatment practices are based on adult data. The penicillins and cephalosporins continue to be a mainstay of therapy because of their broad spectrum of activity, clinical efficacy and favourable tolerability profile. These antibacterials rapidly reach peak serum concentrations and readily diffuse into body tissues. Good penetration into the cerebrospinal fluid (CSF) has made the third-generation cephalosporins the agents of choice for the treatment of bacterial meningitis. These drugs are excreted primarily by the kidney. The carbapenems are broad-spectrum beta-lactam antibacterials which can potentially replace combination regimens. Vancomycin is a glycopeptide antibacterial with gram-positive activity useful for the treatment of resistant infections, or for those patients allergic to penicillins and cephalosporins. Volume of distribution is affected by age, gender, and bodyweight. It diffuses well across serous membranes and inflamed meninges. Vancomycin is excreted by the kidneys and is not removed by dialysis. The aminoglycosides continue to serve a useful role in the treatment of gram-negative, enterococcal and mycobacterial infections. Their volume of distribution approximates extracellular space. These drugs are also excreted renally and are removed by haemodialysis. Passage across the blood-brain barrier is poor, even in the face of meningeal inflammation. Low pH found in abscess conditions impairs function. Toxicity needs to be considered. Macrolide antibacterials are frequently used in the treatment of respiratory infections. Parenteral erythromycin can cause phlebitis, which limits its use. Parenteral azithromycin is better tolerated but paediatric pharmacokinetic data are lacking. Clindamycin is frequently used when anaerobic infections are suspected. Good oral absorption makes it a good choice for step-down therapy in intra-abdominal and skeletal infections. The use of quinolones in paediatrics has been restricted and most information available is in cystic fibrosis patients. High oral bioavailability is also important for step-down therapy. Amphotericin B has been the cornerstone of antifungal treatment in hospitalised patients. Its metabolism is poorly understood. The half-life increases with time and can be as long as 15 days after prolonged therapy. Oral absorption is poor. The azole antifungals are being used increasingly. Fluconazole is well tolerated, with high bioavailability and good penetration into the CSF. Itraconazole has greater activity against aspergillus, blastomycosis, histoplasmosis and sporotrichosis, although it's pharmacological and toxicity profiles are not as favourable.

Clinical use of fluoroquinolones in children

OBJECTIVE

To review the pharmacokinetics, efficacy, and safety of fluoroquinolones in children.

DATA SOURCES

A MEDLINE search (January 1966-March 1998) was conducted for relevant literature.

STUDY SELECTION AND DATA EXTRACTION

Data from compassionate use and published studies were reviewed for the assessment of pharmacokinetics, efficacy, and safety of fluoroquinolones in children.

DATA SYNTHESIS

Fluoroquinolones have a broad spectrum coverage of gram-positive and gram-negative bacteria, including Pseudomonas aeruginosa and intracellular organisms. Fluoroquinolones are well absorbed from the gastrointestinal tract, have excellent tissue penetration, low protein binding, and long elimination half-lives. These antibiotics are effective in treating various infections and are well tolerated in adults. However, the use of fluoroquinolones in children has been restricted due to potential cartilage damage that occurred in research with immature animals. Fluoroquinolones have been used in children on a compassionate basis. Ciprofloxacin is the most frequently used fluoroquinolone in children, most often in the treatment of pulmonary infection in cystic fibrosis as well as salmonellosis and shigellosis. Other uses include chronic suppurative otitis media, meningitis, septicemia, and urinary tract infection. Safety data of fluoroquinolones in children appear to be similar to those in adults. Fluoroquinolones are associated with tendinitis and reversible arthralgia in adults and children. However, direct association between fluoroquinolones and arthropathy remains uncertain.

CONCLUSIONS

Fluoroquinolones have been found to be effective in treating certain infections in children. Additional research is needed to define the optimal dosage regimens in pediatric patients. Although fluoroquinolones appear to be well tolerated, further investigations are needed to determine the risk of arthropathy in children. However, their use in children should not be withheld when the benefits outweigh the risks.

Can tobramycin inhalation be improved with a jet nebulizer?

Data on the pharmacokinetics of antibiotics after inhalation are limited. The aim of this pilot study was to assess the pharmacokinetics of tobramycin under optimalized and standardized aerosol circumstances and, furthermore, to be able to consider possible treatment of exacerbations with inhalation therapy. Six patients were studied after inhalation of 600 mg tobramycin. A jet nebulizer loaded with a 10% solution of tobramycin in water was used. The percentage of the dose that was systemically absorbed ranged from 1.0% to 16.6%. The maximum serum levels of tobramycin ranged from 0.77 mg/L to 3.63 mg/L (mean 1.70 +/- 1.01). The pharmacokinetic data were best described by a two-compartment model. Compared to intravenous administration, the long terminal half-life (mean 9.47 h +/- 3.28 h) could be explained by the slow absorption of tobramycin from the site of administration (flip-flop model). Despite standardized aerosol conditions, considerable interpatient variability was observed. However, the relatively low serum levels allow a further increase of the dose.

Oral ciprofloxacin vs. intravenous ceftazidime plus tobramycin in pediatric cystic fibrosis patients: comparison of antipseudomonas efficacy and assessment of safety with ultrasonography and magnetic resonance imaging. Cystic Fibrosis Study Group

BACKGROUND

More data on the efficacy and safety of ciprofloxacin in pediatric cystic fibrosis patients are needed.

METHODS

One hundred eight pediatric cystic fibrosis patients (ages 5 to 17 years) with acute bronchopulmonary exacerbations entered a randomized multicenter trial designed to compare the safety and efficacy of antipseudomonas therapy with oral ciprofloxacin (15 mg/kg twice daily; maximum dosage 750 mg twice daily) or intravenous ceftazidime plus tobramycin (CAZ/TM) for 14 days.

RESULTS

Clinical improvement was observed in 93% of patients treated with oral ciprofloxacin and in 96% of those receiving parenteral therapy. Transient suppression of Pseudomonas aeruginosa was achieved in 63% of patients at the end of the course of iv CAZ/TM therapy and in 24% receiving ciprofloxacin. Ultrasound examination and nuclear magnetic resonance imaging scans showed no evidence of cartilage toxicity in any of the ciprofloxacin-treated patients. Musculoskeletal adverse events were reported with similar frequency in the two groups of patients (7% in the group receiving ciprofloxacin therapy and 11% in the IV CAZ/TM group). The only sustained musculoskeletal symptom was a case of synovitis in a patient receiving parenteral CAZ/TM.

CONCLUSION

Ciprofloxacin thus appears to be safe and effective for use in young patients with bronchopulmonary exacerbation of cystic fibrosis.

Ciprofloxacin as antipseudomonal treatment in patients with cystic fibrosis

OBJECTIVE

The efficacy and safety of oral ciprofloxacin as a maintenance antipseudomonal therapy were evaluated in 44 patients with cystic fibrosis who had completed a 14-day regimen of intensive hospital therapy with intravenous ceftazidime and amikacin, supplemented by amikacin inhalation therapy.

METHODS

Twenty-one patients were randomly assigned to oral ciprofloxacin alone (Group I) and 23 received ciprofloxacin plus inhaled amikacin (Group II).

RESULTS

Negative sputum cultures were achieved in 34 patients (77%) at the end of intensive therapy (19 Group I and 15 Group II) and were sustained after 3 months of maintenance therapy in 5 of the 19 responders in Group I (26%) and in 8 of the 15 responders in Group II (53%). Resistance to ciprofloxacin was found in 7 of 31 (23%) sputum isolates at the end of ciprofloxacin therapy. During maintenance therapy, continued improvement in clinical symptoms was observed in 14 patients in both treatment groups; 6 in each group had further improvements whereas only 4 patients were clinical failures. There was no correlation between clinical outcome and either elimination of Pseudomonas aeruginosa from sputum culture or development of ciprofloxacin resistance. Both maintenance regimens were well-tolerated by this population of patients which included 28 children younger than 15 years of age. There were no severe or serious adverse events, no signs of quinolone-related arthropathy and no growth impairment.

CONCLUSION

Ciprofloxacin was efficacious, safe and well-tolerated as maintenance antipseudomonal therapy in cystic fibrosis patients. These results suggest further evaluation of ciprofloxacin as an oral maintenance therapy is warranted.

Distribution of DNA and alginate in purulent cystic fibrosis sputum: implications to pulmonary targeting strategies

Cystic fibrosis (CF) patients frequently experience recurring airway infections characterized by thick, viscous sputum. The consistency and nature of these purulent secretions may produce a significant barrier to the successful delivery of drugs and gene therapy vectors designed to treat CF. We have carried out a series of in vitro studies to determine the distribution of two macromolecular components typically present in purulent sputum, bacterial alginate and neutrophil-derived DNA. Sputum samples were obtained from hospitalized CF patients. DNA and alginate were disrupted, respectively, by the in vitro additions of human recombinant deoxyribonuclease I (rhDNase) or alginate lyase prepared from a mucoid strain of Pseudomonas aeruginosa. N-acetyl-L-cysteine (acetylcysteine) was similarly used to collapse the mucin matrix of these samples for comparison. Using a centrifugation-based rheological method known as the compaction assay, a greater maximal response was observed for rhDNase compared to alginate lyase treatment. A simultaneous addition of these enzymes to purulent sputum produced an additive compaction response. Electron microscopy was used to identify alginate and DNA components within the mucin matrix of sputa and to evaluate changes following treatment with high concentrations of alginate lyase or rhDNase. DNA was more widely distributed throughout purulent samples than alginate. Differences in the distribution of DNA and alginate may explain, at least in part, the larger compaction response to rhDNase versus alginate lyase treatment. An improved understanding of DNA and alginate distribution within purulent CF sputum may lead to improvements in drug and vector delivery to airway epithelial cells.

Effect of high-affinity anti-Pseudomonas aeruginosa lipopolysaccharide antibodies induced by immunization on the rate of Pseudomonas aeruginosa infection in patients with cystic fibrosis

Patients with cystic fibrosis (CF; N = 26) and with no prior history of infection with Pseudomonas aeruginosa were immunized with an octavalent O-polysaccharide-toxin A conjugate vaccine. During the next 4 years, 16 patients (61.5%) remained free of infection and 10 (38.5%) became infected. Total serum antilipopolysaccharide (LPS) antibody levels induced by immunization were comparable in infected and noninfected patients. In contrast, 12 of 16 noninfected versus 3 of 10 infected patients (p = 0.024) mounted and maintained a high-affinity anti-LPS antibody response. When compared retrospectively with the rate in a group of age- and gender-matched, nonimmunized, noncolonized patients with CF, the rate at which P. aeruginosa infections were acquired was significantly lower (p < or = 0.02) among all immunized versus nonimmunized patients during the first 2 years of observation. Subsequently, only those immunized patients who maintained a high-affinity anti-LPS antibody response had a significant reduction (p < or = 0.014) in the rate of infection during years 3 and 4. Smooth, typeable strains of P. aeruginosa predominated among immunized patients; rough, nontypeable strains were most frequently isolated from nonimmunized patients. Mucoid variants were isolated from one immunized patient versus six nonimmunized patients. These results indicate that the induction of a high-affinity P. aeruginosa anti-LPS antibody response can influence the rate of infection in patients with CF.

The relationship between infection and inflammation in the early stages of lung disease from cystic fibrosis

We examined the relationship of pulmonary infection and inflammation in cystic fibrosis (CF) by performing 31 bronchoalveolar lavages (BAL) in 14 young children with minimal lung disease from CF. While 10 of the 14 patients had elevated polymorphonuclear leukocyte (PMN) counts initially, only 4 had bacteria generally regarded as pathogenic in the recovered BAL fluid. Three of these 4 and 6 of the others had follow-up bronchoscopies at 6 months intervals. PMN counts remained normal for only one patient. However, pathogenic bacteria were recovered during the repeat BALs only in those patients who were colonized initially. Proinflammatory cytokines and proteinases were generally elevated, and interleukin-8 (IL-8) concentration correlated inversely with oxygen saturation (SaO2). No complications of the procedure occurred. We conclude that BAL identifies inflammation and the presence of bacteria in the lower airway at an early stage of the disease. This information may be used to guide therapy in patients too young or otherwise unable to produce sputum. These data also suggest that inflammation is present early in the course of CF lung disease before colonization and infection of the lungs with potentially pathogenic bacteria occurs. Since inflammation appears to be the earliest detectable evidence of lung disease in CF, monitoring of inflammation with BAL may serve as a useful marker of clinical benefits from new treatments in patients with minimal lung disease.

Correlation between activity of beta-lactam agents in vitro and bacteriological outcome in acute pulmonary exacerbations of cystic fibrosis

A study was conducted to determine whether a direct relationship exists between beta-lactam and/or aminoglycoside activity measured in vitro and bacteriological outcome in acute pulmonary exacerbations of cystic fibrosis. Twenty-seven patients, aged between 6 months and 24 years (mean age 10 1/2 years), were included in the study and received 41 i.v. courses of a beta-lactam agent combined with an aminoglycoside. A total of 63 Pseudomonas aeruginosa strains were found in sputum taken on admission at densities exceeding 10(6) cfu/g of sputum. For each episode, the serum inhibitory quotient (SIQ) and the serum bactericidal quotient (SBQ) of the beta-lactam agent and of the aminoglycoside administered were determined for the Pseudomonas aeruginosa isolate(s). The SIQs and SBQs were calculated by dividing the average peak serum levels achievable in the patients by the minimal inhibitory concentrations and minimal bactericidal concentrations, respectively. The SIQs and SBQs were compared to bacteriological outcome. Bacteriological success was defined as a decrease of 2 log10 counts or more in the Pseudomonas aeruginosa density in sputum between days 0 and 7 of therapy. The SIQ and SBQ of beta-lactam agents were good predictors of bacteriological outcome: SIQs of < 1:16 were 100% predictive of failure (chi 2 28; p < 0.001) and of > or = 1:64 were 92.9% predictive of success (chi 2 35.68; p < 0.001); SBQs of < 1:8 were 100% predictive of failure (chi 2 42.78; p < 0.001) and of > or = 1:32 were 95.8% predictive of success (chi 2 31.5; p < 0.001). Aminoglycoside SIQs and SBQs were not predictive of outcome.

Effects of pentoxifylline on sputum neutrophil elastase and pulmonary function in patients with cystic fibrosis: preliminary observations

High concentrations of free human neutrophil elastase in bronchial epithelial fluid are believed to be a major factor in the evolution of pulmonary injury in cystic fibrosis (CF). To test this hypothesis, we studied pentoxifylline, a compound that inhibits tumor necrosis factor alpha transcription and its stimulatory effect on polymorphonuclear neutrophils, in patients with CF who had chronic Pseudomonas bronchitis. Subjects older than 11 years of age randomly received placebo or pentoxifylline (1600 mg/day) orally, in a double-blind fashion, for 6 months. Pulmonary function and sputum elastase concentrations were determined before therapy and bimonthly during therapy; compliance was determined by measuring serum drug concentrations. Of the 16 patients who completed the study, 9 received pentoxifylline. The sputum elastase concentrations among placebo recipients were significantly increased from baseline at 4 and 6 months (F = 3.44; p < 0.05); the values remained unchanged in the treatment group. The mean forced vital capacity for the placebo group decreased from 59.2% +/- 15.4% predicted at baseline to 52.0% +/- 12.9% predicted at 6 months; the values in the treatment group remained largely unchanged. The forced vital capacity improved between baseline and 6 months for four of nine pentoxifylline recipients and none of the seven control patients (p = 0.09). During the study, four of seven placebo recipients experienced a significant pulmonary exacerbation compared with one of nine treated patients (p = 0.077). These findings support the hypothesis that polymorphonuclear neutrophil elastase is a factor in the evolution of CF lung disease; further studies are needed to define the role of pentoxifylline in the treatment of CF.

The role of bacterial proteases in the pathogenesis of cystic fibrosis

Among the roles of mediators damaging the respiratory epithelium in patients with cystic fibrosis (CF) during the course of chronic, purulent bronchitis, that of neutrophil proteases is well established. The role of bacterial proteases is less well known. Among all pathogens colonizing the airways in CF, Pseudomonas aeruginosa is quantitatively the dominant pathogen; Staphylococcus aureus and Haemophilus influenzae are present in lower numbers. Anaerobic bacteria may be detected in numbers exceeding those of Staphylococcus aureus and Haemophilus influenzae. Among all enzymes secreted by these bacterial strains, Pseudomonas elastase and alkaline protease were shown to be secreted in vivo over prolonged periods in the airways. These enzymes, mainly elastase, have proteolytic activity on many proteins involved in host defense mechanisms, often the same as those hydrolyzed by neutrophil proteases. Pseudomonas elastase has damaging effects on the respiratory epithelium; it has recently also been shown to augment the permeability of the respiratory epithelium cultured in vitro by proteolytic attack of tight junctions. The potential role of proteases and other enzymes secreted by anaerobic bacteria has not been studied in this disease. In conclusion, bacterial proteases secreted in vivo may play a role in the pathogenesis of the airway disease in CF; their relative importance to the role of host proteases is, however, often difficult to determine.

Interferon-gamma downregulates CFTR gene expression in epithelial cells

Cystic fibrosis (CF) is caused by mutations in the CF transmembrane conductance regulator (CFTR) gene, resulting in defective transepithelial Cl- transport. The regulation of CF gene expression is not fully understood. We report that interferon-gamma (IFN-gamma), but not IFN-alpha or -beta, downregulates CFTR mRNA levels in two colon-derived epithelial cell lines, HT-29 and T84, in a time- and concentration (from 0.1 IU/ml)-dependent manner. IFN-gamma has no effect on the transcription rate of the CFTR gene but reduces CFTR mRNA half-life, indicating that it exerts a posttranscriptional regulation of CFTR expression, at least partly, through destabilization of the transcripts. Cells treated with IFN-gamma contain subnormal amounts of 165-kDa CFTR protein. Assays of adenosine 3',5'-cyclic monophosphate-stimulated 36Cl- efflux and whole cell currents show that CFTR function is diminished in IFN-gamma-treated cells. IFN-gamma and tumor necrosis factor-alpha synergistically reduce CFTR gene expression. Our results suggest that production of these cytokines in response to bacterial infections and inflammatory disorders may alter transmembrane Cl- transport.

Pulmonary retention of free and liposome-encapsulated tobramycin after intratracheal administration in uninfected rats and rats infected with Pseudomonas aeruginosa

The pulmonary residence time of free and liposome-encapsulated tobramycin was studied with uninfected rats and rats infected with Pseudomonas aeruginosa. Chronic infection in lungs was established by intratracheal administration of 10(8) CFU of P. aeruginosa PA 508 prepared in agar beads. After 3 days, a single dose (300 micrograms) of free or liposome-encapsulated tobramycin was given intratracheally to both infected and uninfected rats. At various time intervals (0.25 to 16 h) after drug instillations, the remaining tobramycin was evaluated in blood, lungs, and kidneys by a microbiological assay. Intratracheal instillation of liposome-encapsulated tobramycin resulted in high and sustained levels of tobramycin in lungs of uninfected and infected rats over the 16-h period studied; however, the tobramycin levels were two times higher in uninfected rats. There was no tobramycin detected in the blood or kidneys from these animals. In contrast, the intratracheally instilled free tobramycin was cleared within 3 and 1 h from the lungs of uninfected and infected animals, respectively. These data suggest that the encapsulation of tobramycin in liposomes can result in a significant increase of its residence time within lungs. This study also shows that pulmonary infection was associated with a lowering of tobramycin levels in lungs.

New perspectives in understanding and management of the respiratory disease in cystic fibrosis

In the past 40 years, the mean survival of patients with cystic fibrosis (CF) has increased from less than 1 year to 30 years. The identification of the gene mutated in CF in 1989 has already been followed by the first phase of somatic gene therapy in 1993. The target organ of somatic gene therapy is the respiratory epithelium, which is progressively damaged by the chronic infection and inflammation characteristic of the disease. Since in the future, more patients may benefit from somatic gene therapy, the understanding of the mechanisms leading to chronic infection and inflammation becomes increasingly important. In the future, current therapeutic measures to protect the respiratory epithelium from damage, such as intravenous antimicrobial treatment, will be improved by the additional delivery of new drugs to the bronchial tree by aerosol. Amiloride and recombinant human DNAse administered by this route have the potential to improve mucociliary clearance. Antibiotics as well as protease inhibitors delivered by aerosol should contribute to prevent damage by infection and inflammation in order to increase the probability of successful somatic gene therapy in this disease.

Reduction in viscosity of cystic fibrosis sputum in vitro by gelsolin

Obstruction of airways by viscous sputum causes lung damage in patients with cystic fibrosis (CF). Sputum samples from CF patients were shown to contain filamentous actin. Human plasma gelsolin, a protein that severs actin filaments, rapidly decreased the viscosity of CF sputum samples in vitro. Gc globulin and deoxyribonuclease I, proteins that sequester monomeric actin but do not sever actin filaments, were less efficient than gelsolin in diminishing sputum viscosity. These results suggest that gelsolin may have therapeutic potential as a mucolytic agent in CF patients.

Efficacy of aerosolized tobramycin in patients with cystic fibrosis

BACKGROUND

Direct aerosol delivery of aminoglycosides such as tobramycin to the lower airways of patients with cystic fibrosis may control infection with Pseudomonas aeruginosa and improve pulmonary function, with low systemic toxicity. We conducted a randomized crossover study to evaluate the safety and efficacy of aerosolized tobramycin in patients with cystic fibrosis and P. aeruginosa infections.

METHODS

Seventy-one patients with stable pulmonary status were recruited from seven U.S. centers for the treatment of cystic fibrosis and randomly assigned to one of two crossover regimens. Group 1 received 600 mg of aerosolized tobramycin for 28 days, followed by half-strength physiologic saline (placebo) for two 28-day period. Group 2 received placebo for 28 days, followed by tobramycin for two 28-day periods. Pulmonary function, the density of P. aeruginosa in sputum, ototoxicity, nephrotoxicity, and the emergence of tobramycin-resistant P. aeruginosa were monitored.

RESULTS

In the first 28-day period, treatment with tobramycin was associated with an increase in the percentage of the value predicted for forced expiratory volume in one second (9.7 percentage points higher than the value for placebo; P < 0.001), forced vital capacity (6.2 percentage points higher than the value for placebo; P = 0.014), and forced expiratory flow at the midportion of the vital capacity (13.0 percentage points higher than the value for placebo; P < 0.001). A decrease in the density of P. aeruginosa in sputum by a factor of 100 (P < 0.001) was found during all periods of tobramycin administration. Neither ototoxicity nor nephrotoxicity was detected. The frequency of the emergence of tobramycin-resistant bacteria was similar during both tobramycin and placebo administration.

CONCLUSIONS

The short-term aerosol administration of a high dose of tobramycin in patients with clinically stable cystic fibrosis is an efficacious and safe treatment for endobronchial infection with P. aeruginosa.

Host inflammatory responses to first isolation of Pseudomonas aeruginosa from sputum in cystic fibrosis

Pseudomonas aeruginosa infection of the respiratory tract in patients with cystic fibrosis is a major determinant of morbidity and mortality. However, it has been postulated that the earliest phase of colonization is not associated with injury. To test this hypothesis we determined the association of the first recorded isolation of P. aeruginosa from the sputum on circulating markers of the inflammatory response in 6 patients with cystic fibrosis. At this time circulating C-reactive protein was increased in all 6 and neutrophil elastase alpha 1-antitrypsin complex (elastase-complex) was increased in 5 patients compared with healthy controls. This inflammatory response was associated with a reduction in the FEV1 and FVC of all patients [FEV1, 1.42 +/- 0.87 L (mean +/- SD) at first isolation vs. 2.08 +/- 0.74 L before isolation; P < 0.05; FVC, 1.94 +/- 0.93 L vs. 2.87 +/- 1.01 L, P < 0.05]. At a median interval of 10 months, 5 patients had raised titres of positive IgG antibody to P. aeruginosa, indicating significant exposure to this organism. At this time, lung function had returned to preinfection levels, whilst 3 patients showed continuing features of an inflammatory response, and the group mean value for elastase-complex was raised. Our findings demonstrate that at the time of first isolation of P. aeruginosa from the sputum of patients with cystic fibrosis, there is a concomitant systemic host response and an acute deterioration of pulmonary function.

The role of saliva in aggregation and adherence of Pseudomonas aeruginosa in patients with cystic fibrosis

The aggregation and adherence activity of P. aeruginosa, mediated by whole saliva from cystic fibrosis (CF) patients and non-CF subjects, was investigated. CF saliva-mediated aggregation of P. aeruginosa was stronger than the activity of non-CF saliva. Likewise, P. aeruginosa adherence to buccal epithelial cells (BEC) of CF patients was stronger than to BEC of non-CF subjects. Adherence of non-mucoid P. aeruginosa to BEC of CF patients was increased by saliva, whereas the mucoid variant was not. CF patients colonized with P. aeruginosa showed higher adherence of the non-mucoid variant than non-colonized CF patients. CF patients with high saliva-mediated adherence of non-mucoid P. aeruginosa also had high salivary aggregation activity. Increased CF saliva-mediated aggregation activity may be linked to the increased non-mucoid P. aeruginosa adherence to BEC of CF patients.

Drug treatment of pneumonia in the hospital. What are the choices?

Mortality and morbidity of nosocomial pneumonia remain high. Successful treatment of pulmonary infections depends on several factors including type of infection, offending pathogen, status of host defences, and adequate choice of antibiotic therapy. The physician's decision should aim at achieving antibiotic concentrations beyond the MIC at the site of infection. Gram-negative bacilli, notably Pseudomonos aeruginosa, Klebsiella pneumoniae and Escherichia coli, remain the most frequent agents in nosocomial pneumonia. Staphylococcus aureus and Streptococcus pneumoniae predominate among the Gram-positive cocci. Pneumocystis carinii predominates in immunocompromised patients. Protected sample bronchoscopy associated with quantitative cultures of samples, and quantification of intracellular microorganisms in cells recovered by broncho-alveolar lavage are two promising procedures which might replace previous, more aggressive methods. Penetration of antibiotics into lung tissue depends on physicochemical properties of the drug and the degree of inflammation of lung tissue. Quinolones, macrolides, tetracyclines and trimethoprim penetrate well into bronchial secretions. Penetration is moderate to low for aminoglycosides and beta-lactams. Fluoroquinolones and new beta-lactam agents, including third-generation cephalosporins imipenem, aztreonam and ticarcillin-clavulanate, showed comparative clinical efficacy in treatment of nosocomial pneumonia, with an efficacy rate close to 80%. Aminoglycosides should not be used alone. Combination therapy reduces but does not eliminate the risk of selection of Gram-negative resistant mutants. It should not be used routinely except for P. aeruginosa, Enterobacter cloacae and Serratia marcescens infections.

Safety and immunogenicity of Pseudomonas aeruginosa conjugate A vaccine in cystic fibrosis

To assess the safety and immunogenicity of a Pseudomonas aeruginosa octavalent O-polysaccharide-toxin A conjugate vaccine, 22 patients (mean age 7 years) with cystic fibrosis who had no history of colonisation with P aeruginosa were immunised with the vaccine. Adverse reactions were mild and self-limiting. IgG antibody concentrations to all vaccine antigens were significantly raised after vaccination and remained so for 12 months. Immunisation produced opsonic and toxin A neutralising antibodies. A booster dose given at 12 months led to an anamnestic response. There was no significant change in clinical status after vaccination. Further work to assess efficacy in patients with cystic fibrosis can now be considered since our findings support the safety and immunogenicity of the vaccine.

Microbiology of airway disease in patients with cystic fibrosis

Individuals with cystic fibrosis have abbreviated life spans primarily due to chronic airway infection. A limited number of types of organisms are responsible for these infections, with Staphylococcus aureus and Pseudomonas aeruginosa being of primary importance. In the pre-antibiotic era, greater than 90% of deaths due to infection were caused by S. aureus and death usually occurred in the first 2 years of life. With the advent of effective antistaphylococcal therapy, life spans increased and P. aeruginosa became the pathogen of primary importance. P. aeruginosa isolates recovered from patients with cystic fibrosis have a unique phenotypic characteristic referred to as "mucoid." The mucoid phenotype is due to the production of a mucoid exopolysaccharide. A mucoid exopolysaccharide is believed to play a central role in the establishment of chronic pseudomonal lung infection in these patients. A third organism, Pseudomonas cepacia, has recently been detected in the airways of older patients with cystic fibrosis and is associated with increased mortality. The virulence of P. cepacia is not understood, but the organism is extremely refractory to antimicrobial therapy. Other bacteria, including Haemophilus influenzae and members of the family Enterobacteriaceae, appear to play a secondary role in airway infection. Aspergillus fumigatus is the most important fungal agent causing allergic bronchopulmonary disease. The role of viruses has only recently been examined. At least in some patients with cystic fibrosis, respiratory syncytial virus may be important in predisposing to subsequent bacterial infections.

Cystic fibrosis. 2. Lung injury in cystic fibrosis

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Recombinant human DNase I reduces the viscosity of cystic fibrosis sputum

Respiratory distress and progressive lung destruction in cystic fibrosis can be attributed to bacterial persistence and the accumulation of viscous purulent secretions in the airways. More than 30 yr ago it was suggested that the large amounts of DNA in purulent secretions contribute to its viscosity and that bovine pancreatic DNase I could reduce the viscosity. To evaluate the potential clinical utility of recombinant human DNase I (rhDNase) in the treatment of cystic fibrosis, we have cloned, sequenced, and expressed rhDNase. Catalytic amounts of rhDNase greatly reduce the viscosity of purulent cystic fibrosis sputum, transforming it within minutes from a nonflowing viscous gel to a flowing liquid. The reduction in viscosity is associated with a decrease in size of DNA in the sputum. Inhalation of a rhDNase aerosol may be a simple direct approach that will help individuals with cystic fibrosis and other patients with pneumonia or bronchitis to clear their airways of purulent secretions.

Pulmonary function and clinical course in patients with cystic fibrosis after pulmonary colonization with Pseudomonas aeruginosa

To evaluate the relationship between Pseudomonas aeruginosa colonization and the development of lung disease, we studied 895 patients who attended our cystic fibrosis clinic between 1975 and 1988. The prevalence of P. aeruginosa colonization was 82%. Patients who acquired P. aeruginosa in the first year of life had a similar 10-year survival rate (85%) to that in patients who were colonized between the ages of 1 and 7 years (87%), and to that in patients colonized after the age of 7 years (78%). One year before colonization, mean age, forced expiratory volume in 1 second (FEV1), forced vital capacity, and forced expiratory flow in the mid-expiratory phase were similar to those in a group of patients who remained free of P. aeruginosa. No significant change in pulmonary function variables could be demonstrated 1 year and 2 years after the colonization. The rate and duration of hospitalization did not increase in the years after P. aeruginosa colonization compared with the years before colonization. By the age of 7 years, the mean percentage of predicted FEV1 was lower by 10% in patients who were already colonized by P. aeruginosa compared with those who were not colonized (p less than 0.01). A similar reduction in FEV1 was observed at all ages from 7 to 35 years, but no precipitate rate of decline in FEV1 could be associated with P. aeruginosa colonization. We conclude that although P. aeruginosa colonization is associated with 10% lower lung function, it does not cause an immediate and rapid reduction, as has been previously reported. The clinical course and the pulmonary deterioration in cystic fibrosis after P. aeruginosa colonization is a gradual and variable process.

Antistaphylococcal antibodies in cystic fibrosis

Chronic colonization with Staphylococcus aureus is found in 40-50% of the sputum producing patients with cystic fibrosis treated at Stockholm's Cystic Fibrosis Center, Huddinge University Hospital. 30-40% of these patients had increased ELISA IgG antibody titres against teichoic acid and against alpha-toxin. About half of the number of patients showed increased antibody titres to either antigen during infection. Increased antibody titres against staphylococcal antigens were only found in less than or equal to 10% of patients not chronically colonized with S. aureus (no different from the normal population). The serum titres of antistaphylococcal antibodies were significantly higher in the chronically colonized patients (p less than 0.001). Patients who were also chronically harbouring Pseudomonas aeruginosa had the highest titres of both antibodies. The titres increased with clinical signs of infection and were normalized by antimicrobial chemotherapy. To conclude, the use of ELISA IgG antibodies may prove suitable for routine evaluation of the need for, and control of the efficacy of antistaphylococcal chemotherapy in cystic fibrosis.

Clinical significance of Staphylococcus aureus in cystic fibrosis

Staphylococcus aureus is usually the first bacterial pathogen detected in the respiratory secretions of patients with cystic fibrosis. This review briefly examines the characteristics of this host-parasite relationship in terms of current knowledge about the toxicity of the organism, mechanisms of respiratory tract injury, therapy and prevention. Recent evidence indicates that viral infection plays a role in the initial damage of the respiratory epithelial cells and staphylococcal colonization ensues. Affinity of staphylococcus for cystic fibrosis mucus, mucociliary abnormalities and unknown factors contribute to persistent colonization with this organism causing progressive pulmonary damage and possibly influencing Pseudomonas infection. Most of the evidence today indicates that aggressive antibiotic management directed against S. aureus is warranted in all stages of bronchopulmonary infection in cystic fibrosis. Future efforts to prevent colonization and the toxic and immunopathic consequences of staphylococcal infection are also important. One study is in progress that examines antibiotic prevention in the early stages of cystic fibrosis. Future investigations need to address other strategies including vaccines, antitoxins, anti-inflammatory agents, immunomodulators, and antibiotic regimens.

The relationship between atopy and cystic fibrosis

The incidence and clinical significance of allergy in cystic fibrosis have been discussed. There is little evidence that the high prevalence of positive allergy skin tests in CF is a clinical manifestation of a hypersensitivity lung disease complicating the primary pulmonary disorder, except in the special case of allergic bronchopulmonary aspergillosis. The lung disease of CF appears to be caused by excessive bronchial secretions and recurrent infection that are the result of abnormal ion transport across the apical membrane of the respiratory epithelial cell. There are two important questions concerning the allergic reactions: Are they clinically significant, and, why do they occur? The former question is partly resolved by the data presented, although well-controlled studies of intervention would help to resolve it further. The cause of these reactions, which occur particularly in relationship to the mold Aspergillus fumigatus, is unknown but the author is inclined to the view that they are the result of recurrent infection that induces heightened immunologic reactivity to inhaled allergens. The significance of AF may be simply that this mold has a "predilection for diseased airways" or may be more complex; for example, owing to abnormal ion composition in respiratory secretions, abnormal lectin expression by CF respiratory epithelial cells, or selective filtration by the airways based on particle size.

Antipseudomonal therapy in cystic fibrosis: aztreonam and amikacin versus ceftazidime and amikacin administered intravenously followed by oral ciprofloxacin

In order to determine the optimal antipseudomonal therapy in patients with cystic fibrosis aztreonam plus amikacin was compared to ceftazidime plus amikacin, and these two-week hospital regimens were followed by oral ciprofloxacin given for four weeks. Fifty-six cases of acute pulmonary exacerbation of the disease in 42 patients associated with isolation of Pseudomonas aeruginosa from the sputum were randomly treated with either aztreonam or ceftazidime (300mg/kg/day i.v.; maximum daily dose 12g) in combination with amikacin (36mg/kg/day i.v.; maximum daily dose 1,500mg). Other aspects of the two-week treatment were constant. The two therapy groups were comparable in all respects. Both regimens were well tolerated and resulted in similar improvements in clinical, bacteriologic, radiologic and laboratory findings, and pulmonary function. Fifty patients could be reevaluated after subsequent outpatient therapy consisting of oral ciprofloxacin (30mg/kg/day; maximum daily dose 1,500mg) given for four weeks. During this period, the clinical and laboratory improvements persisted, and the rate of eradication of Pseudomonas aeruginosa from sputum decreased from 62% to 34%. Ciprofloxacin was well tolerated and there was no drug toxicity or serious adverse effect. In the 25 prepubertal patients there was neither subjective nor objective evidence of skeletal drug toxicity. In patients with cystic fibrosis, aztreonam or ceftazidime in combination with amikacin represents an effective and safe systemic anti-pseudomonal therapy. Subsequent oral ciprofloxacin therapy for four weeks prolongs the beneficial effects and is well tolerated.

Whole, submandibular, and parotid saliva-mediated aggregation of Pseudomonas aeruginosa in cystic fibrosis

The aggregation of mucoid and nonmucoid Pseudomonas aeruginosa by submandibular, parotid, and whole saliva from patients with cystic fibrosis (CF) and non-CF subjects was investigated. There were significant differences (P less than 0.01) in aggregation of mucoid and nonmucoid variants of P. aeruginosa by submandibular and whole saliva from CF patients and non-CF subjects. However, the differences in the parotid secretion were not as pronounced. Patients with CF who were colonized with P. aeruginosa demonstrated a significantly higher (P less than 0.05) percent aggregation of the mucoid variants by the submandibular secretion and of both mucoid and nonmucoid variants by whole saliva, compared with corresponding secretions from patients with CF not colonized with this pathogen. The parotid saliva aggregation activity was not markedly different for the two groups with CF. From patients with CF, whole saliva demonstrated a higher percent P. aeruginosa aggregation than did the submandibular saliva. In non-CF subjects, however, the percent aggregation of P. aeruginosa by submandibular saliva was higher than that by whole saliva. Our results indicate that the sero-mucous products of the submandibular gland have a more significant role in P. aeruginosa aggregation than the serous secreting parotid cells and that the submandibular secretion is possibly responsible for the differences in oral colonization by this pathogen in subjects with and without CF.

Inhibition of Pseudomonas aeruginosa exoenzyme expression by subinhibitory antibiotic concentrations

We examined the effects of subinhibitory concentrations of ciprofloxacin, tobramycin, and ceftazidime on Pseudomonas aeruginosa exoenzyme expression in vitro and in vivo. Exotoxin A, exoenzyme S, phospholipase C, elastase, and total protease activities were suppressed by antibiotics at concentrations as low as 1/20 of the MIC over a 24-h period in broth. Continuous 10-day exposure of P. aeruginosa DG1 broth cultures to antibiotic levels equal to 1/10 of the MIC reduced exoenzyme S activity in all treatment groups. Elastase activity was reduced only by ciprofloxacin and tobramycin treatment. This suppressive effect of the antibiotics persisted throughout the 10 days and was not influenced by the increase in MIC of ciprofloxacin detected during the course of the experiment. Rats chronically infected with P. aeruginosa were treated with subinhibitory doses of antibiotics and compared with untreated controls. Bacterial numbers in lung homogenates from each of the four study groups were identical. However, the lungs from antibiotic-treated rats had significantly less histological damage than those from control rats (P less than 0.001). The protective effect was greatest for ciprofloxacin and tobramycin. Further, P. aeruginosa isolates from ciprofloxacin- and tobramycin-treated rats demonstrated significantly less exoenzyme S and elastase activity than isolates from untreated rats (P less than 0.001). Isolates from ceftazidime-treated lungs expressed less exoenzyme S activity (P less than 0.001) but an equivalent amount of elastase activity as isolates from controls. The suppression of P. aeruginosa exoenzymes may arrest progressive lung injury during chronic P. aeruginosa lung infections.

Effect of pyochelin on Pseudomonas cepacia respiratory infections

Exogenously supplied pyochelin influenced the virulence of Pseudomonas cepacia pyochelin-negative strains in a chronic pulmonary infection model in rats. Groups of rats were inoculated transtracheally with agar beads containing P. cepacia or P. aeruginosa strains, saturated with either pyochelin or PBS. Supplementation of the inocula with pyochelin had no effect on the number of bacteria recovered from the lungs. The availability of pyochelin, however, increased the degree of pathology observed in lungs infected with pyochelin-negative strains of P. cepacia. The area of pathological involvement in the lung was about 2-fold larger, when pyochelin was present. Inclusion of pyochelin in the inoculum had no effect on the degree of pathology observed in lungs infected with a pyochelin-positive P. aeruginosa strain. Pyochelin was shown to stimulate in vitro growth of P. cepacia, but it had no effect on production of lipase or protease, factors which may be involved in P. cepacia virulence. These studies support our hypothesis that pyochelin may be important for dissemination in P. cepacia infections.

Sputum changes associated with therapy for endobronchial exacerbation in cystic fibrosis

We sought to define objective indicators of the resolution of Pseudomonas aeruginosa endobronchial infection in patients with cystic fibrosis. We prospectively studied 75 patients admitted for treatment of a pulmonary exacerbation and quantitated sputum bacterial density, DNA content, and the concentration of albumin and total protein in sputum, and compared these values with clinical evaluation. Eleven of the 75 patients had systemic signs, fever, and leukocytosis, which we arbitrarily defined as due to endobronchial infection. At the end of hospitalization, these 11 patients were afebrile, had peripheral leukocyte counts in the normal range, and were judged improved. Sputum P. aeruginosa density, DNA content, and total protein content on admission were similar in the two illness groups. Hospitalization and parenteral antibiotic administration for an average of 14.6 days were associated with improved pulmonary function in all 75 subjects (P values for forced vital capacity, forced expiratory volume at 1 second, and peak expiratory flow rate were all less than 0.001). With improvement, there was a decrease in sputum P. aeruginosa density (mean of both groups decreased from 10(7.80) CFU/g on admission to 10(5.96) CFU/g; P less than 0.001), and a decreased DNA concentration (overall mean 4.73 +/- 4.75 on admission to 2.76 +/- 2.49 mg/g; P less than 0.002). The decrease in sputum total protein concentration for both groups was not significant (overall mean 60.5 +/- 48.4 to 43.9 +/- 38.2 mg/g; P = 0.06). Sputum albumin concentrations did not change in either group. We conclude that in cystic fibrosis subjects with a pulmonary exacerbation, bacterial density, sputum DNA and protein content decrease with hospitalization and parenteral antibiotic therapy. At the end of treatment, these indices of sputum infection and inflammation correlate with improved pulmonary function and clinical improvement. These changes are independent of the presence or absence of fever on admission.

Comparison of piperacillin alone versus piperacillin plus tobramycin for treatment of respiratory infections in children with cystic fibrosis

Seventeen patients with cystic fibrosis (CF) and pulmonary exacerbations were randomly assigned to two treatment groups: piperacillin 600 mg/kg/day (P), and piperacillin 600 mg/kg/day plus tobramycin (PT), in order to determine the safety and pharmacokinetics of high-dose piperacillin and whether piperacillin alone was effective for the treatment of Pseudomonas infections. The mean half-life of piperacillin was 0.54 hours, with a peak concentration of 232 micrograms/ml. No differences between P and PT groups were noted in clinical assessment, as judged by Shwachman scores, pulmonary function testing, or weight gain. However, during the course of treatment, quantitative sputum cultures decreased by greater than 10(2) colony-forming units in only 5 out of 19 Pseudomonas isolates from the P group, compared with 12 of 19 isolates from the PT group (P less than 0.03, Chi-square). Although emergence of resistance was not seen, one isolate had an increase in minimum inhibitory concentration from 8 to 128 micrograms/ml. There were no serious adverse reactions to piperacillin; only one patient developed fever possibly related to piperacillin. Therapy with high-dose piperacillin was safe in children with CF. Treatment with piperacillin alone was less effective than combination therapy with gentamicin for reduction in titer of Pseudomonas in sputum. However, the role of antimicrobial agents in the treatment of CF remains undefined. A double-blind placebo-controlled trial is indicated.

Prevalence and significance of methicillin-resistant Staphylococcus aureus in patients with cystic fibrosis

Recent reports indicate that methicillin-resistant Staphylococcus aureus (MRSA) may be emerging as a significant pediatric nosocomial pathogen. Children with cystic fibrosis (CF) pulmonary disease are subject to many of the risk factors for MRSA colonization and/or infection. We retrospectively investigated the prevalence and significance of MRSA from sputum and throat cultures in 452 patients with CF followed during 1986. No MRSA had been isolated during 1984 or 1985. Although S. aureus was isolated from 212 patients (47%) in 1986, only 14 (3%) showed MRSA. The MRSA strains had 11 different antimicrobial susceptibility patterns. Neither age, clinical condition, nor recent prior hospitalization correlated with MRSA acquisition. Acquisition did not appear to directly affect the course of the pulmonary disease in these patients even though no patient received any treatment for their MRSA. The prevalence of MRSA is low, although patients with CF are subject to many risk factors. MRSA appears to be mainly community-acquired and to represent colonization rather than infection. However, the potential for nosocomial MRSA infection is present, and vigilance is required in monitoring any changes in frequency of isolation or infection with these organisms.

Randomized trial of ceftazidime versus placebo in the management of acute respiratory exacerbations in patients with cystic fibrosis

A randomized trial of ceftazidime versus placebo was conducted in patients with cystic fibrosis hospitalized for acute respiratory exacerbations. Patients 12 years of age or older were included if they had mild to moderately severe illness according to the following criteria: erythrocyte sedimentation rate less than or equal to 50 mm/hr and less than three other abnormalities (leukocyte count greater than or equal to 15,000/microliter, pulse greater than or equal to 100 beats/min, respirations greater than or equal to 30/min, or temperature greater than or equal to 38.5 degrees C). In all 16 episodes treated with ceftazidime, the patients were rated improved in comparison with 10 of 12 patients treated with placebo. Three placebo-treated patients dropped out of the study within 3 to 5 days because they wanted antibiotic therapy. None of the 15 placebo-treated patients showed clinical deterioration. There were no significant differences in rate of improvement of symptom score, weight gain, or pulmonary function between the two treatment groups. There was no difference in the course during the 6 to 24 months after the study period. Intravenous antibiotics are not essential in the management of all acute respiratory exacerbations of mild to moderate severity in patients with cystic fibrosis.

Management of Pseudomonas aeruginosa lung infection in Danish cystic fibrosis patients

The annual mortality rate of cystic fibrosis patients with chronic Pseudomonas aeruginosa lung infection at the Danish CF-centre ranged from 10 to 20% in the years 1970-1975. In this period the patients received antipseudomonal chemotherapy only during acute exacerbations of infection. From 1976 99 patients acquired chronic P. aeruginosa infection and were given regular and intensive antipseudomonal treatment 3-4 times per year. The patients were followed for 612 patient-years; 7 died and the 10-year survival rate after onset of P. aeruginosa infection was 90% +/- 4%. The annual mortality rate is now 1-2%. Although precipitating antibodies against P. aeruginosa increased significantly, pulmonary function did not deteriorate with duration of infection. Cross-infection between patients caused an increased incidence of chronic P. aeruginosa infection which was reduced by hygienic measures.