Adhering ability of Stenotrophomonas maltophilia is dependent on growth conditions

The growth conditions are known to influence the bacterial adhesion to different kinds of surfaces. In the present study the adhering ability of Stenotrophomonas maltophilia, on growth in nutrient rich media (Tryptic Soy Broth (TSB)) and minimal media (Luria Bertani (LB)) was checked by viable cell count and spectrophotometric method. TSB grown S. maltophilia showed higher adhesion compared to bacteria grown in LB broth, to both biotic and abiotic surfaces. However, when bacteria were grown in LB broth supplemented with different concentrations of glucose, under aerobic conditions, the bacteria grown at lower glucose concentration (2 gm/l) showed maximum adhesion to abiotic surfaces (polystyrene microtiter plate) compared to biotic surfaces (mouse trachea, mouse tracheal mucus and HEp-2 cells line). Maximum adhesion to biotic surfaces was seen with cells grown at 4 gm/l of glucose concentration. On the contrary if the cell was grown under microaerophilic conditions maximum adhesion to abiotic and biotic surfaces was achieved with bacteria grown at 1 gm/l and 2 gm/l of glucose concentration respectively. A negative correlation was observed between glucose concentrations and pH of media, the latter declined faster under microaerophilic conditions as compared to aerobic condition.

Usefulness of quantitative endotracheal aspirate cultures in intensive care unit patients with suspected pneumonia

It is difficult to differentiate pathogens responsible for pneumonia or colonization in patients with an endotracheal tube or in patients that have undergone tracheostomy. We evaluated the clinical usefulness of quantitative endotracheal aspirates cultures and sought to determine the result threshold level for positivity. The authors performed this retrospective cohort study between December 1, 2004 and January 31, 2006. Forty-five suspected pneumonia patients admitted to an intensive care unit (ICU) with quantitative bronchoalveolar lavage (BAL) and endotracheal aspirate (EA) culture results were enrolled. Using a threshold of 10(5) cfu/mL, 10 of the 45 (22.2%) quantitative EA cultures were positive, as compared with 7 (15.6%) BAL cultures. When BAL culture findings were used as the reference, the sensitivity and specificity of quantitative EA cultures were 85.7% and 89.5%, respectively, at a threshold of 10(5) cfu/mL, and 85.7% and 94.7%, respectively, at a threshold of 10(6) cfu/mL. Of the 10 EA culture positive patients, 2 patients with a result of -10(5) cfu/mL were BAL culture negative. The quantitative EA culture is a useful non-invasive tool for the diagnosis of pneumonia pathogens. It is suggested that a threshold level of 10(6) cfu/mL is appropriate.

Phenylbutyrate counteracts Shigella mediated downregulation of cathelicidin in rabbit lung and intestinal epithelia: a potential therapeutic strategy

Background

Cathelicidins and defensins are endogenous antimicrobial peptides (AMPs) that are downregulated in the mucosal epithelia of the large intestine in shigellosis. Oral treatment of Shigella infected rabbits with sodium butyrate (NaB) reduces clinical severity and counteracts the downregulation of cathelicidin (CAP-18) in the large intestinal epithelia.

Aims

To develop novel regimen for treating infectious diseases by inducing innate immunity, we selected sodium 4-phenylbutyrate (PB), a registered drug for a metabolic disorder as a potential therapeutic candidate in a rabbit model of shigellosis. Since acute respiratory infections often cause secondary complications during shigellosis, the systemic effect of PB and NaB on CAP-18 expression in respiratory epithelia was also evaluated.

Methods

The readouts were clinical outcomes, CAP-18 expression in mucosa of colon, rectum, lung and trachea (immunohistochemistry and real-time PCR) and release of the CAP-18 peptide/protein in stool (Western blot).

Principal findings

Significant downregulation of CAP-18 expression in the epithelia of rectum and colon, the site of Shigella infection was confirmed. Interestingly, reduced expression of CAP-18 was also noticed in the epithelia of lung and trachea, indicating a systemic effect of the infection. This suggests a causative link to acute respiratory infections during shigellosis. Oral treatment with PB resulted in reduced clinical illness and upregulation of CAP-18 in the epithelium of rectum. Both PB and NaB counteracted the downregulation of CAP-18 in lung epithelium. The drug effect is suggested to be systemic as intravenous administration of NaB could also upregulate CAP-18 in the epithelia of lung, rectum and colon.

Conclusion

Our results suggest that PB has treatment potential in human shigellosis. Enhancement of CAP-18 in the mucosal epithelia of the respiratory tract by PB or NaB is a novel discovery. This could mediate protection from secondary respiratory infections that frequently are the lethal causes in dysentery.

[The comparison of different bronchial aspirate culturing methods in patients with ventilator-associated pneumonia (VAP)]

BACKGROUND

Although broncho-alveolar lavage (BAL) culture and protected specimen brush (PSB) are regarded as the most effective methods in the diagnosis of VAP, a simple endotracheal aspiration (EA) is frequently performed during routine care, because of its simplicity and low cost. We compared the effectiveness of EA with BAL and PSB in VAP patients.

METHODS

Sixty-one adult VAP patients, ventilated for longer than 48 h, were cultured with all three methods.

RESULTS

Positive cultures were obtained from 63.9% of patients, with Acinetobacter baumannii being the most common pathogen. There was a high positive correlation between simple aspirates and BAL (k 0.817, CI 0.664-0.840, p <0.001) and aspirates and PSB (k 0.667, CI 0.483-0.871, p <0.001).

CONCLUSION

Because of the high sensitivity of bronchial aspirate culturing, compared to BAL and PSB, it can be used successfully in most cases.

Additive effect of rPb27 immunization and chemotherapy in experimental paracoccidioidomycosis

Paracoccidioidomycosis, PCM, the major systemic mycosis in Latin America, is caused by the termally dimorphic fungus Paracoccidioides brasiliensis and requires extended periods of chemotherapy with a significant frequency of relapsing disease. The search for new alternatives of treatment is necessary. rPb27 is an antigenic protein from P. brasiliensis that already showed a significant protective activity as a vaccine for PCM in experimental models. The cDNA of rPb27 was subcloned into a pET-DEST 42 plasmid, expressed in E. coli with a his-tag and purified by affinity chromatography. Immunization with this recombinant protein and chemotherapy were used together in an attempt to improve treatment of PCM. For this, BALB/c mice were challenged with pathogenic P. brasiliensis strain and after immunized with rPb27, in the presence of Corynebacterium parvum and Al(OH)₃, some groups were also treated with fluconazole. After 40 days of treatment, the combined drug/rPb27 administration controlled PCM in the liver and spleen, with long lasting protection, and largely preserved tissues structures of these organs. Additionally, in the lungs after 40 days of treatment there was a significant reduction in the fungal load and size of lesions. At the same time, the levels of TNF-α were higher than infected-only mice. Moreover, significant levels of anti-rPb27 specific IgG1, IgG2a and IgG2b isotypes were detected in the sera of mice immunized with rPb27 fluconazole treated or not. These results showed an additive protective effect of rPb27 immunization and chemotherapy, suggesting that an rPb27-based vaccine can be used to enhance PCM antifungal treatment.

Dissemination of class 1, 2 and 3 integrons among different multidrug resistant isolates of Acinetobacter baumannii in Tehran hospitals, Iran

A total of 100 non-duplicate Acinetobacter baumannii isolates were collected from different hospitals in Tehran and were confirmed as A. baumannii by conventional biochemical and API testing. Antimicrobial susceptibility of these isolates was checked by a disk diffusion method in accordance with CLSI guidelines. The isolates were then detected as carrying class 1 and 2 integron gene cassettes by PCR evaluation and then genotyped by REP-PCR. More than 50% (n = 50) of the isolates were multidrug resistant. The results showed that more than 80% of all multidrug resistant A. baumannii strains carry a class 1 integron. Distribution of IntI 1 and IntI2 among A. baumannii isolates was 58% and 14%, respectively. Analysis of a conserved segment of class 1 integron showed a range from 100 bp to 2.5 kb. REP-PCR fingerprinting showed more than 20 genotypes among A. baumannii strains. TIhere was no relationship between REP genotypes and the distribution of different classes of integrons. This is a comprehensive study on the distribution of different classes of integrons among A. baumannii in Iran. Considering the exact role of integrons in coding drug resistance in bacteria, the findings of this study could help us find antimicrobial resistant mechanisms among A. baumannii isolates in Iran.

Tracheobronchial aspergillosis following primary cutaneous aspergillosis in a lung-transplant recipient

Invasive aspergillosis, a major problem during the post-transplant period, typically presents with pneumonia or tracheobronchitis in lung transplant recipients. In contrast, primary cutaneous aspergillosis is very rarely observed in lung-transplant recipients. In this report, we describe a case of tracheobronchial aspergillosis following primary cutaneous aspergillosis in a lung-transplant recipient. Early diagnosis of tracheobronchial aspergillosis is important because occult tracheobronchial aspergillosis can be potentially lethal. Our report suggests that surveillance bronchoscopy may facilitate identification of occult tracheobronchial invasion in lung-transplant recipients with primary cutaneous aspergillosis.

Bacterial internalization is not sufficient to clear Pseudomonas aeruginosa infection in human fetal airway xenografts

BACKGROUND

Pseudomonas aeruginosa is an opportunistic pathogen that causes chronic endobronchial infections in cystic fibrosis (CF) patients. The role of bacterial internalization in the clearance of P. aeruginosa from the airways is controversial.

MATERIAL/METHODS

A xenograft model was used to study P. aeruginosa strain PAO-1 clearance and internalization by the human airways in vivo. Human lung and tracheal rudiments, obtained from therapeutic abortions (20±2 weeks of gestation), were subcutaneously implanted in the flanks of SCID mice and infected after 14-22 weeks of engraftment. Lungs were surgically exposed and P. aeruginosa was injected in the pulmonary parenchima. Opercula closing the tracheal openings were excised, mucus removed, and bacterial inoculum was injected into the lumen. Internalization was studied at 4 hours post-infection on single-cell suspensions, while clearance was evaluated after 24-72 hours from the infection on homogenized tissues.

RESULTS

Tracheae and lungs were morphologically identical to the adult human tissues, as evaluated by standard histology. Both types of xenografts showed a very low level of bacterial internalization (0.004-0.25% of total recovered bacteria), although tracheal xenografts presented more than 100 times greater internalization than did lung xenografts. Both lung and tracheal xenografts did not clear the injected bacteria for each inocolum, even at very low doses (100 colony forming units).

CONCLUSIONS

P. aeruginosa internalization by epithelial cells occurs, albeit at very low levels, and is not sufficient to clear bacteria in the airway xenograft model. This model could be used for studying chronic respiratory infections in CF patients.

[Molecular genetic features of structure of gene coding tracheal colonization factor in Bordetella pertussis strains]

AIM

Comparative analysis of structure of tcfA gene coding tracheal colonization factor of Bordetella pertussis strans isolated in Moscow from patients with pertussis.

MATERIALS AND METHODS

Ninety-seven strains of B. pertussis isolated in different periods of pertussis infection epidemic process (1948 - 1989--from collection of Gabrichevsky Moscow Research Institute of Epidemiology and Microbiology; 1990 - 2007--isolated in Moscow from patients with pertussis) were studied. Primers for amplification of tcfA gene region with size 945 n.p. were used. Amplicons obtained in PCR were used for sequencing. Nucleotide sequences of tcfA gene types of B. pertussis strains were matched to EMBL/GenBank database.

RESULTS

Sequencing of tcfA gene fragments revealed two sequence variants. Ninety-six of 97 studied B. pertussis strains had the same sequence variant--variant 1. The one strain was characterized by other nucleotide sequence--variant 2, which differed from variant 1 by presence of insertion g in position 396 that led to reading frame shift.

CONCLUSION

The structure of tcfA gene circulating population of B. pertussis strains is homogenous and is characterized by presence of "vaccine" allele dominating in majority of countries in the world.

The "fever workup" and respiratory culture practice in critically ill trauma patients

PURPOSE

Fever and leukocytosis (FAL) in critically ill patients often triggers a "workup" that includes a respiratory secretion culture (RCx). We evaluated our respiratory culture practice associated with FAL. We hypothesized that FAL would be associated with a RCx, but would not be associated with a positive culture or treating a respiratory infection in critically injured patients during their first 14 intensive care unit (ICU) days.

MATERIALS AND METHODS

An 18-month retrospective analysis was performed on consecutive ICU trauma patients admitted for 2 days or more to a level I trauma center. Data collected included demographics, injuries, RCxs (bronchoalveolar lavage or tracheal aspirate), maximum daily temperature, and a daily leukocyte count during the first 14 ICU days.

RESULTS

A total of 510 patients with a mean age of 49 and injury severity score of 19 were evaluated for a total of 3839 patient-days. Two hundred eleven patients had 489 RCxs obtained (2.4 RCxs/patient); 94 (19%) were obtained on consecutive days. Obtaining a RCx was associated with fever (relative risk, 4.8; 95% confidence interval, 4.1-5.8) and the combination of FAL (relative risk, 2.6; 95% confidence interval, 2.2-3.1), but not leukocytosis alone. Fever, leukocytosis, or FAL did not predict a positive RCx. One hundred twenty-eight patients were treated for a respiratory infection. Treatment of respiratory infections was contrary to the RCx results 24% of the time. The sensitivity and specificity of a positive RCx being associated with respiratory infection were 97% and 46%, respectively.

CONCLUSIONS

Fever and leukocytosis were associated with the decision to obtain RCxs but were not associated with positive RCxs in our ICU practice. Respiratory secretion culture results had a low specificity and did not consistently impact treatment decisions. Factors other than fever and leukocytosis alone should influence the decision to obtain RCxs during the first 14 days in the ICU after trauma.

Comparison of the serial surveillance with quantitative and non-quantitative tracheal aspirate in predicting ventilator-associated pneumonia etiology in patients receiving antibiotic therapy

BACKGROUND

The aim of this study was to investigate the value of serial quantitative (QC) and non-quantitative (NQC) endotracheal aspirate (ETA) surveillance cultures in predicting the causative pathogen of ventilator associated pneumonia (VAP) in patients receiving antibiotic therapy and the factors associated with their predictive value. This was a prospective observational cohort study carried out in the Intensive Care Unit of a tertiary hospital.

METHODS

The study enrolled 109 patients receiving mechanical ventilation for at least four days. Tracheal surveillance cultures were obtained routinely thrice weekly. Each sample was processed non-quantitatively and quantitatively (103 and 105 cfu/mL). The sensitivity, specificity and predictive values (true positives plus true negatives) of these cultures for the development of VAP were evaluated, and the causative pathogens were assessed.

RESULTS

Sixty-eight VAP episodes were detected during this period. The NQCs and QCs detected the responsible pathogens of VAP in 63% and 28% of the VAP patients, respectively. Surveillance with NQC and QC were negative in 78% and 85% of the patients without VAP, respectively. Compared with the QC-ETAs (47%), NQC-ETAs (65%) were more predictive in all of the 109 patients. The NQC-ETA and QC-ETA predicted the causative pathogens at 3.3+/-2.7 days and 2.5+/-1.7 days prior to the development of VAP episodes, respectively. Both NQC and QC surveillance cultures were less predictive in older patients, and QCs were less predictive in A. baumannii infections.

CONCLUSION

These results suggest that surveillance with NQ-ETA is better than the Q-ETA in predicting the development and causative pathogen of VAP in patients who have already been receiving antibiotic therapy.

[Antimicrobial and antimycotic therapy in the surgery of iatrogenic esophageal and tracheal diseases]

Microbiologic analysis of tracheal and gastrostomic discharge was performed in 327 patients with iatrogenic injuries of trachea and esophagus, operated during 2003-2008. Main groups of microorganisms, colonizing the tracheobronchial tree were defined. St. epidermalis was defined in 3.9-13.3%, St. aureus - in 12.4-21.1%, Ps. small a. Cyrilliceruginosa - in 9.2-17.5% of cases. Increase of Candidae colonization was revealed (7.8-12.2%). The increase of polyresistant strains identification was typical. St. epidermalis and St. aureus demonstrated the preserving high sensitivity to vankomycin and linesolide, whereas Ps. aeruginosa showed the growth of resistance to all groups of antibiotics, but polymyxin. The common decrease of antibiotic activity requires the realization of complex antibacterial and antimycotic treatment.

The suitability of selected methods of nucleic acid extraction for detecting Rhodococcus equi DNA in tracheobronchial wash fluid using PCR

The aim of the present study was to compare the effectiveness of selected DNA extraction methods for the detection of Rhodococcus equi from tracheobronchial wash fluid by PCR. Three methods of nucleic acid extraction were evaluated, based mainly on the activity of proteolytic enzymes. A commercial kit for isolation and purification of bacterial DNA was also used in the study. In one procedure, an additional component, the cationic detergent CTAB, was used. It has been found that the traditional enzyme digestion methods used with the tracheobronchial wash fluid are more suitable to prepare DNA matrix for PCR comparing with commercial DNA isolation kit. Minimum numbers of bacteria detected with the use of traditional enzyme digestion methods and commercial kit were 100 and 500 cells, respectively. Based on the results of the study we can recommend the enzymatic digestion method along with CTAB as an additional component.

Pan-resistant Acinetobacter infection in neonates in Karachi, Pakistan

BACKGROUND

Pan-resistant Acinetobacter infection has emerged as an important nosocomial pathogen in our inpatient neonates over the past few years.

METHODOLOGY

We performed a retrospective chart review during a five-year period (July 2003 - June 2008) of all neonates hospitalized in our neonatal intensive care unit (NICU) who developed Acinetobacter infection to identify mortality-associated risk factors in Acinetobacter neonatal infection.

RESULTS

During the five-year study period, 122 cultures from 78 neonates grew Acinetobacter. Source sites of positive culture were in the following descending order: blood (n = 57), trachea (n = 55), tissue/wound/body fluids (n = 4), eye (n = 4), urine (n = 1), and cerebrospinal fluid (n = 1). Twenty-four (31%) patients had Acinetobacter isolated from more than one site. At the time of admission the mean age was 2.08 +/- 4 days and mean weight was 1.77 +/- 0.88 kg; 75% were premature. Pan-resistance (87/122; sensitive only to Polymyxin) was present in 71% of Acinetobacter isolates. Crude mortality rate of this cohort was 47%, while 70% of patients died within four days after positive Acinetobacter culture. We identified weight of less than 1 kg on admission (p 0.06, adjusted Odds Ratio (AOR) 1.53), gestational age 28 weeks or less (p 0.011, AOR 2.88), poor perfusion (p 0.007, AOR 2.4), thrombocytopenia (p 0.01; AOR 1.6) and metabolic acidosis (p 0.01; AOR 1.67) as predictors associated with poor outcome.

CONCLUSION

Pan-resistant Acinetobacter infection is exceedingly fatal in newborns, particularly in premature and very low-birth weight neonates. Rational antibiotic use and vigilant infection control in NICUs are key to controlling multi-drug resistant Acinetobacter infection and improving clinical outcome.

Comparison of semi-quantitative endotracheal aspirates to quantitative non-bronchoscopic bronchoalveolar lavage in diagnosing ventilator-associated pneumonia

BACKGROUND

Current strategies for diagnosing ventilator-associated pneumonia (VAP) favor the use of quantitative methods; however, semi-quantitative cultures of endotracheal aspirates are still commonly used.

METHODS

The microbiological results of patients with suspected VAP who had both quantitative cultures with non-bronchoscopic bronchoalveolar lavage (BAL) and semi-quantitative cultures of endotracheal aspirate obtained within 24 hours of each other were retrospectively reviewed and compared, using a quantitative threshold of >or=10(4) colony-forming units/mL as a reference standard.

RESULTS

256 patients with paired cultures were identified. Concordance between endotracheal aspirate (any growth of pathogens) and non-bronchoscopic BAL was complete in 58.2% and completely discordant in 23.8%. The sensitivity and specificity of endotracheal aspirate were 65.4% and 56.1%, which improved to 81.2% and 61.9% when antibiotic management decisions were considered in the analysis. Twenty-six patients had endotracheal aspirate cultures that were falsely negative for pathogens, with 61.5% of these patients demonstrating growth of non-fermenting Gram-negative rods or methicillin-resistant Staphylococcus aureus (MRSA) on non-bronchoscopic BAL. Overall, 45 patients (17.5%) among the entire cohort had false positive endotracheal aspirate cultures, with 19 of these patients (42.2%) demonstrating growth of non-fermenting Gram-negative rods or MRSA.

CONCLUSIONS

Semi-quantitative cultures of endotracheal aspirate are poorly concordant with quantitative cultures obtained via non-bronchoscopic BAL. Although the performance of endotracheal aspirate improves when antibiotic treatment is considered, guiding therapy on the basis of semi-quantitative cultures may still result in failure to identify potentially multiple-drug-resistant pathogens, and would also tend to promote excessive antibiotic usage. Our data support the use of quantitative cultures in diagnosing VAP.

Dissemination of class I integron in Acinetobacter baumliannii isolated from ventilator-associated pneumonia patients and their environment

Multidrug resistant Acinetobacter baumannii has become the most common cause of health care-associated infections at Maharaj Nakhon Si Thammarat Hospital, Thailand. The objective of the study was to detect integrons using PCR-based method from 96 A. baumannii isolates from ventilator-associated pneumonia (VAP) patients and their environment. Antibiotic susceptibility was determined using a disk diffusion technique. Forty-six isolates exhibited integrase genes, with only class I and class II integron detected in 43 and 3 A. baumannii isolates, respectively. Twenty-seven of 52 clinical and 19 of 44 environmental isolates were integron-positive. Detection rate of integron-positive A. baumannii isolated from VAP patients increased from 25% to 83% over the 4 month study period. The majority (91%) of integron-positive A. baumannii showed resistance to 6 or more of 11 antibiotics tested and 72% of class I integron-positive isolates were imipenem-resistant. Thus, class I integron-positive A. baumannii had spread among the VAP patients and into hospital environment, the latter acting as reservoirs of potential pathogens possessing drug resistance genes.

Can routine surveillance samples from tracheal aspirate predict bacterial flora in cases of ventilator-associated pneumonia?

AIM

The aim of this study was to investigate the hypothesis that periodical sampling of the tracheo-bronchial tree in the absence of clinical suspicion of pneumonia is useful to identify bacteria responsible for subsequent late ventilator associated pneumonia (VAP). This was a retrospective observational human study carried out in two medical-surgical intensive care units of two different hospitals. From January 1999 to December 2000, 559 patients, who received invasive respiratory support for more than 48 hours, were screened.

METHODS

Tracheal aspiration (TA) was performed once or twice weekly in all mechanically ventilated patients. The microbiological findings from TA surveillance cultures done in the eight days before suspicion of VAP were compared to those isolated from the positive diagnostic samples done for late onset VAP (after more than four days of mechanical ventilation). The sensitivity, specificity, and positive/negative predictive values of the ability of the surveillance sample to anticipate the VAP pathogen were calculated.

RESULTS

Among the microorganisms isolated from TA, 68% were retrieved from diagnostic samples. All VAP pathogens previously isolated were from 43% of the TA samples. If TA was collected 2-4 days before the clinical diagnosis of VAP, pathogens were detected in 58% of samples. In contrast, only 27% were collected more than four days earlier (P<0.05). The positive predictive values for Pseudomonas aeruginosa and methicillin resistant Staphylococcus aureus from routine TA samples were 92% and 90%, respectively. The negative predictive values for Pseudomonas aeruginosa and methicillin resistant Staphylococcus aureus from routine TA samples were 75% and 89%, respectively.

CONCLUSIONS

TA cultures in ventilated patients may help to predict pathogens. Early detection may lead to earlier treatment in long term ventilated patients when VAP is suspected.

New microbicidal functions of tracheal glands: defective anti-infectious response to Pseudomonas aeruginosa in cystic fibrosis

Tracheal glands (TG) may play a specific role in the pathogenesis of cystic fibrosis (CF), a disease due to mutations in the cftr gene and characterized by airway inflammation and Pseudomonas aeruginosa infection. We compared the gene expression of wild-type TG cells and TG cells with the cftr DeltaF508 mutation (CF-TG cells) using microarrays covering the whole human genome. In the absence of infection, CF-TG cells constitutively exhibited an inflammatory signature, including genes that encode molecules such as IL-1alpha, IL-beta, IL-32, TNFSF14, LIF, CXCL1 and PLAU. In response to P. aeruginosa, genes associated with IFN-gamma response to infection (CXCL10, IL-24, IFNgammaR2) and other mediators of anti-infectious responses (CSF2, MMP1, MMP3, TLR2, S100 calcium-binding proteins A) were markedly up-regulated in wild-type TG cells. This microbicidal signature was silent in CF-TG cells. The deficiency of genes associated with IFN-gamma response was accompanied by the defective membrane expression of IFNgammaR2 and altered response of CF-TG cells to exogenous IFN-gamma. In addition, CF-TG cells were unable to secrete CXCL10, IL-24 and S100A8/S100A9 in response to P. aeruginosa. The differences between wild-type TG and CF-TG cells were due to the cftr mutation since gene expression was similar in wild-type TG cells and CF-TG cells transfected with a plasmid containing a functional cftr gene. Finally, we reported an altered sphingolipid metabolism in CF-TG cells, which may account for their inflammatory signature. This first comprehensive analysis of gene expression in TG cells proposes a protective role of wild-type TG against airborne pathogens and reveals an original program in which anti-infectious response was deficient in TG cells with a cftr mutation. This defective response may explain why host response does not contribute to protection against P. aeruginosa in CF.