Pseudomonas aeruginosa strains isolated from animal with high virulence genes content and highly sensitive to antimicrobials.

OBJECTIVES: P. aeruginosa is one of the most metabolically versatile bacteria having the ability to survive in multiple environments through its accessory genome. An important hallmark of P. aeruginosa is the high level of antibiotic resistance, which often makes eradication difficult and sometimes impossible. Evolutionary forces have led to this bacterium to develop high antimicrobial resistance with a variety of elements contributing to both intrinsic and acquired resistance. The objectives were to genetically and phenotypically characterizer P. aeruginosa strains isolated from companion animals of different species. METHODS: We characterized a collection of 39 P. aeruginosa strains isolated from infected animals. The genetic characterization was in relation to chromosomal profile by PFGE; content of virulence gene; presence of genomic islands (GIs); genes of the cytotoxins exported by T3SS: exoU, exoS, exoT and exoY; and type IV pili allele. The phenotypic characterization was based on patterns of susceptibility to different antimicrobials. RESULTS: Each strain had a PFGE profile, a high virulence genes content, and a large accessory genome. However, most of the strains presented high sensitivity to almost all antimicrobials tested, showing no acquired resistance (no ß-lactamases). The exception to this lack of resistance was seen with penicillin. CONCLUSIONS: P. aeruginosa could be a naturally sensitive bacterium to standard antimicrobials but could rapidly develop intrinsic and acquired resistance when the bacterium is exposed to pressure exerted by antibiotics, as observed in hospital settings.

A Pilot Study Of Aspirin Resistance In Obstructive Sleep Apnea Patients.

Purpose: Obstructive sleep apnea (OSA) leads to endothelial dysfunction and platelet hyperactivity, which are linked to increased risk of cardiovascular disease and implicated in the development of aspirin resistance. We hypothesized that aspirin resistance is prevalent among OSA patients and aimed to explore effects of continuous positive airway pressure (CPAP) therapy on aspirin responsiveness. Methods: In Phase 1, prevalence of aspirin resistance was determined cross-sectionally in a group of OSA patients (n=59) on daily low-dose aspirin (81 mg) taken before entering the study, for primary or secondary prevention. In Phase 2, aspirin responsiveness before and after initiation of CPAP therapy was compared and stratified by endothelial function in a cohort of aspirin-naïve patients with newly diagnosed OSA (n=18). Results: In Phase 1, prevalence of aspirin resistance was 17%; most patients (56%) were on CPAP therapy. In Phase 2, initiation of CPAP therapy was associated with significant improvement in endothelial function (p=0.03). The mean pre-CPAP aspirin resistance units (ARU) was 569 (SD=75). In subjects with endothelial dysfunction (44%), the mean decrease after initiation of CPAP therapy was 43 ARU (SD=81, p=0.18). In contrast, subjects with normal endothelial function experienced the mean decrease of 8 ARU (SD=116, p=0.83). Conclusion: Aspirin resistance may be prevalent among OSA patients. After initiation of CPAP therapy, we observed a trend towards improvement in aspirin responsiveness among patients with endothelial dysfunction. The role of endothelial dysfunction and aspirin resistance should be explored in further studies that focus on the effect of CPAP on cardiovascular outcomes.

High expression of Helicobacter pylori VapD in both the intracellular environment and biopsies from gastric patients with severity.

Helicobacter pylori is a Gram-negative bacterium that causes chronic atrophic gastritis and peptic ulcers and it has been associated with the development of gastric adenocarcinoma and mucosa-associated lymphoid tissue (MALT). One of the more remarkable characteristics of H. pylori is its ability to survive in the hostile environment of the stomach. H. pylori regulates the expression of specific sets of genes allowing it to survive high acidity levels and nutrient scarcity. In the present study, we determined the expression of virulence associated protein D (VapD) of H. pylori inside adenocarcinoma gastric (AGS) cells and in gastric biopsies. Using qRT-PCR, VapD expression was quantified in intracellular H. pylori-AGS cell cultures at different time points and in gastric mucosa biopsies from patients suffering from chronic atrophic gastritis, follicular gastritis, peptic ulcers, gastritis precancerous intestinal metaplasia and adenocarcinoma. Our results show that vapD of H. pylori presented high transcription levels inside AGS cells, which increased up to two-fold above basal values across all assays over time. Inside AGS cells, H. pylori acquired a coccoid form that is metabolically active in expressing VapD as a protection mechanism, thereby maintaining its permanence in a viable non-cultivable state. VapD of H. pylori was expressed in all gastric biopsies, however, higher expression levels (p = 0.029) were observed in gastric antrum biopsies from patients with follicular gastritis. The highest VapD expression levels were found in both antrum and corpus gastric biopsies from older patients (>57 years old). We observed that VapD in H. pylori is a protein that is only produced in response to interactions with eukaryotic cells. Our results suggest that VapD contributes to the persistence of H. pylori inside the gastric epithelial cells, protecting the microorganism from the intracellular environment, reducing its growth rate, enabling long-term infection and treatment resistance.

Fingerprint Analysis and Identification of Strains ST309 as a Potential High Risk Clone in a Pseudomonas aeruginosa Population Isolated from Children with Bacteremia in Mexico City.

Pseudomonas aeruginosa is an opportunistic pathogen and is associated with nosocomial infections. Its ability to thrive in a broad range of environments is due to a large and diverse genome of which its accessory genome is part. The objective of this study was to characterize P. aeruginosa strains isolated from children who developed bacteremia, using pulse-field gel electrophoresis, and in terms of its genomic islands, virulence genes, multilocus sequence type, and antimicrobial susceptibility. Our results showed that P. aeruginosa strains presented the seven virulence genes: toxA, lasB, lecA, algR, plcH, phzA1, and toxR, a type IV pilin alleles (TFP) group I or II. Additionally, we detected a novel pilin and accessory gene, expanding the number of TFP alleles to group VI. All strains presented the PAPI-2 Island and the majority were exoU+ and exoS+ genotype. Ten percent of the strains were multi-drug resistant phenotype, 18% extensively drug-resistant, 68% moderately resistant and only 3% were susceptible to all the antimicrobial tested. The most prevalent acquired ß-Lactamase was KPC. We identified a group of ST309 strains, as a potential high risk clone. Our finding also showed that the strains isolated from patients with bacteremia have important virulence factors involved in colonization and dissemination as: a TFP group I or II; the presence of the exoU gene within the PAPI-2 island and the presence of the exoS gene.

Serum surfactant protein D (SP-D) is a prognostic marker of poor outcome in patients with A/H1N1 virus infection.

INTRODUCTION: Surfactant protein D (SP-D) plays an important role in the innate responses against pathogens and its production is altered in lung disorders. METHODS: We studied the circulating levels of SP-D in 37 patients with acute respiratory distress syndrome due to the A/H1N1 virus infection and in 40 healthy controls. Cox logistic regression models were constructed to explore the association of SP-D levels and risk of death. RESULTS: Mortality rate after a 28-day was 32.42 %. Significant higher levels of SP-D were detected in A/H1N1 patients with fatal outcome (p < 0.05). After adjusting for confounding variables, levels of SP-D ≥250 ng/mL were associated with increased the risk of death (HR = 8.27, 95 % CI 1.1-64.1, p = 0.043). CONCLUSIONS: Our results revealed that higher circulating levels of SP-D are associated with higher mortality risk in critically ill A/H1N1 patients. SP-D might be a predictive factor of poor outcomes in viral pneumonia.

Distribution of CYP2D6 and CYP2C19 polymorphisms associated with poor metabolizer phenotype in five Amerindian groups and western Mestizos from Mexico.

BACKGROUND: The distribution of polymorphisms in the CYP2D6 and CYP2C19 genes allows inferring the potential risk for specific adverse drug reactions and lack of therapeutic effects in humans. This variability shows differences among human populations. The aim of this study was to analyze single-nucleotide polymorphisms related to a poor metabolizer (PM) phenotype in nonpreviously studied Amerindian groups and Mestizos (general admixed population) from Mexico. METHODS: We detected by SNaPshot(®) different polymorphisms located in CYP2D6 (*3, *4, *6, *7, and *8) and CYP2C19 (*2, *3, *4 and *5) in western Mestizos (n=145) and five Amerindian groups from Mexico: Tarahumaras from the North (n=88); Purépechas from the Center (n=101); and Tojolabales (n=68), Tzotziles (n=88), and Tzeltales (n=20) from the Southeast. Genotypes were observed by capillary electrophoresis. The genetic relationships among these populations were estimated based on these genes. RESULTS AND DISCUSSION: The wild-type allele (*1) of both genes was predominant in the Mexican populations studied. The most widely observed alleles were CYP2C19*2 (range, 0%-31%) and CYP2D6*4 (range, 1.2%-7.3%), whereas CYP2D6*3 was exclusively detected in Mestizos. Conversely, CYP2C19*4 and *5, as well as CYP2D6*3, *6, *7, and *8, were not observed in the majority of the Mexican populations. The Tarahumaras presented a high frequency of the allele CYP2C19*2 (31%) and of homozygotes *2/*2 (10.7%), which represent a high frequency of potentially PM phenotypes in this Amerindian group. The genetic distances showed high differentiation of Tarahumaras (principally for CYP2C19 gene). In general, a relative proximity was observed between most of the Amerindian, Mexican-Mestizo, and Latin-American populations. CONCLUSION: In general, the wild-type allele (*1) predominates in Mexican populations, outlining a relatively homogeneous distribution for CYP2C19 and CYP2D6. The exception is the Tarahumara group that displays a potentially increased risk for adverse reactions to CYP2C19-metabolized drugs.

Genetic and phenotypic characterization of a Pseudomonas aeruginosa population with high frequency of genomic islands.

Various genomic islands, PAPI-1, PAPI-2, PAGI-1, PAGI-2, PAGI-3, and PAGI-4, and the element pKLC102 have been characterized in different P. aeruginosa strains from diverse habitats and geographical locations. Chromosomal DNA macroarray of 100 P. aeruginosa strains isolated from 85 unrelated patients hospitalized in an intensive care unit was created to assess the occurrence of these genomic islands (GEIs). The macroarray was then hybridized with labeled probes derived from each genomic island. In addition, PFGE patterns with SpeI, frequency of virulence genes, and antimicrobial resistance patterns of the strains were studied. Our results showed that almost all P. aeruginosa strains presented up to eight virulence genes. By SpeI macrorestriction fragment analysis we were able to identify 49 restriction patterns; 35 patterns correspond to single strains and the remaining 14 to strains subgroup (a-n). Most of the strains showed variation in number or composition of GEIs and a specific antimicrobial pattern indicating that each strain was an unrelated isolate. In terms of the number of genomic islands per strain, 7 GEIs were found in 34% of the strains, 6 in 18%, 5 in 12%, 4 in 14%, 3 in 10%, 2 in 7%, and 1 in 4%; only one isolate did not present any GEI. The genomic islands PAPI-1 and PAPI-2 and the element pKLC102 were the most frequently detected. The analysis of the location of each GEI in the chromosome of two strains show that the islands PAGI-3, PAPI-1, PAPI-2 and pKLC102 are present in the insertion site previously reported, but that PAGI-2 and PAGI-4 are inserted in another chromosome place in a site not characterized yet. In conclusion our data show that P. aeruginosa strains exhibited an epidemic population structure with horizontal transfer of DNA resulting in a high frequency of GEIs.

Transfusion-related acute lung injury in the critically ill: prospective nested case-control study.

RATIONALE: Acute lung injury (ALI) that develops 6 hours after transfusion (TRALI) is the leading cause of transfusion-related mortality. Several transfusion characteristics have been postulated as risk factors for TRALI, but the evidence is limited to retrospective studies. OBJECTIVES: To compare patient and transfusion risk factors between patients who do and do not develop ALI. METHODS: In this prospective cohort study, consecutive transfused critically ill patients were closely observed for development of ALI. Donor samples were collected from the transfusion bags. Risk factors were compared between patients who developed ALI after transfusion and transfused control patients, matched by age, sex, and admission diagnosis. MEASUREMENTS AND MAIN RESULTS: Seventy-four of 901 transfused patients developed ALI within 6 hours of transfusion (8%). Compared with transfused control subjects, patients with ALI were more likely to have sepsis (37 vs. 22%, P = 0.016) and a history of chronic alcohol abuse (37 vs. 18%, P = 0.006). When adjusted for patient characteristics, transfusion of plasma from female donors (odds ratio [OR], 5.09; 95% confidence interval [95% CI], 1.37-18.85) rather than male donors (OR, 1.60; 95% CI, 0.76 to 3.37), number of pregnancies among the donors (OR, 1.19; 95% CI, 1.05 to 1.34), number of donor units positive for anti-granulocyte antibodies (OR, 4.85; 95% CI, 1.32-17.86) and anti-HLA class II antibodies (OR, 3.08; 95% CI, 1.15-8.25), and concentration of lysophosphatidylcholine in the donor product (OR, 1.69; 95% CI, 1.10 to 2.59) were associated with the development of ALI. CONCLUSIONS: Both patient and transfusion risk factors determine the probability of ALI after transfusion. Transfusion factors represent attractive targets for the prevention of ALI.

Chronic nitrofurantoin-induced lung disease.

OBJECTIVE: To reassess the clinical and radiological features of chronic nitrofurantoin-induced lung disease and eventual clinical outcome. PATIENTS AND METHODS: We retrospectively reviewed the medical records of 18 patients with chronic nitrofurantoin-induced lung disease who were seen at the Mayo Clinic in Rochester, Minn, from January 1, 1997, to December 31, 2002. RESULTS: The median age of the 18 patients was 72 years (range, 47-90 years) at the time of diagnosis; 17 (94%) were women. Onset of symptoms occurred after a median interval of 23 months (range, 10-144 months) following the initiation of nitrofurantoin therapy for the prevention of recurrent urinary tract infections. All patients presented with persistent dyspnea and cough associated with lung infiltrates detected on chest radiography. Ten computed tomograms were available for review and revealed bilateral areas of ground-glass opacities in all cases and showed subpleural Irregular linear opacities and patchy consolidation in some cases. Nitrofurantoin therapy was discontinued in all patients, and most improved subsequently; 9 patients received corticosteroid therapy. CONCLUSIONS: Chronic nitrofurantoin-induced lung disease is seen predominantly in older women who present with respiratory symptoms after a year or more of nitrofurantoin therapy. Associated radiological features are relatively nonspecific but usually include bilateral areas of ground-glass opacities on computed tomography of the chest. Cessation of nitrofurantoin therapy leads to improvement and suffices in the management of some patients, although corticosteroid therapy may be helpful in those more severely affected.

New insights into the pathology of acute respiratory failure.

PURPOSE OF REVIEW: The purpose of this review is to provide a historical perspective and to analyze the recent advances in the understanding of the cellular and tissue pathology of acute respiratory failure, specifically of the acute respiratory distress syndrome. The scope of mechanisms involved in acute lung injury and acute respiratory distress syndrome is far too great to do it justice in a single review. Therefore, this review will focus only on recent advances in the understanding of the morphologic changes that occur in acute lung injury, acute respiratory distress syndrome, and ventilator-induced lung injury. RECENT FINDINGS: The use of fluorescent labels brought a novel method to identify and quantify cell wounding in the whole organ animal model of ventilator-induced lung injury. Real-time in vivo microscopy demonstrated the injurious effects of alveolar instability in the pathogenesis of ventilator-induced lung injury. Lipid tether mechanics, using laser tweezers, have advanced the understanding of the mechanical properties of the plasma membrane in response to mechanical stress. New animal injury models have brought forward new insights into the pathogenesis and structural abnormalities seen in acute respiratory distress syndrome. Apoptosis and epithelial wounding and repair have been examined in novel methods, and new mechanisms in lung edema formation have been proposed. SUMMARY: New mechanisms in the pathology of acute respiratory failure have shifted the focus to lung mechanics, tissue damage, remodeling, and the systemic effects derived from the mechanical stress imposed by the ventilator in patients with adult respiratory distress syndrome.

Ventilator-associated lung injury in patients without acute lung injury at the onset of mechanical ventilation.

OBJECTIVE: Although ventilation with small tidal volumes is recommended in patients with established acute lung injury, most others receive highly variable tidal volume aimed in part at normalizing arterial blood gas values. We tested the hypothesis that acute lung injury, which develops after the initiation of mechanical ventilation, is associated with known risk factors for ventilator-induced lung injury such as ventilation with large tidal volume. DESIGN: Retrospective cohort study. SETTING: Four intensive care units in a tertiary referral center. PATIENTS: Patients who received invasive mechanical ventilation for > or = 48 hrs between January and December 2001. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: The main outcome of interest, acute lung injury, was assessed by independent review of daily digital chest radiographs and arterial blood gases. Ventilator settings, hemodynamics, and acute lung injury risk factors were extracted from the Acute Physiology and Chronic Health Evaluation III database and the patients' medical records. Of 332 patients who did not have acute lung injury from the outset, 80 patients (24%) developed acute lung injury within the first 5 days of mechanical ventilation. When expressed per predicted body weight, women were ventilated with larger tidal volume than men (mean 11.4 vs. 10.4 mL/kg predicted body weight, p <.001) and tended to develop acute lung injury more often (29% vs. 20%, p =.068). In a multivariate analysis, the main risk factors associated with the development of acute lung injury were the use of large tidal volume (odds ratio 1.3 for each mL above 6 mL/kg predicted body weight, p <.001), transfusion of blood products (odds ratio, 3.0; p < 0.001), acidemia (pH < 7.35; odds ratio, 2.0; p =.032) and a history of restrictive lung disease (odds ratio, 3.6; p =.044). CONCLUSIONS: The association between the initial tidal volume and the development of acute lung injury suggests that ventilator-associated lung injury may be an important cause of this syndrome. Height and gender should be considered when setting up the ventilator. Strong consideration should be given to limiting large tidal volume, not only in patients with established acute lung injury but also in patients at risk for acute lung injury.

Acute lung injury after blood transfusion in mechanically ventilated patients.

BACKGROUND: Liberal transfusion strategy increases the risk of acute lung injury (ALI), but specific transfusion-related factors have not been characterized. We tested the hypotheses that storage age and specific type of blood products are associated with increased risk of ALI in mechanically ventilated patients. STUDY DESIGN AND METHODS: From a database of mechanically ventilated patients, we identified those who received blood products during the first 48 hours of intensive care. We extracted information about underlying ALI risk factors as well as the type, amount, and shelf age of administered blood products. Outcome was assessed by an independent, blind review of chest radiographs and clinical findings. RESULTS: Of 181 patients transfused during the first 48 hours of mechanical ventilation, 60 (33%) developed ALI. There was no difference in average duration of red blood cells storage between patients who did and did not develop ALI (median, 18.5 vs. 17.5 days; p = 0.22). In a multivariable logistic regression analysis, important risk factors associated with the development of ALI were thrombocytopenia (odds ratio, 5.9; p = 0.004) and transfusion of fresh frozen plasma (odds ratio, 3.2; p = 0.023). CONCLUSION: Thrombocytopenia and transfusion of fresh frozen plasma, but not storage age of red blood cells, were associated with the development of ALI in this cohort of mechanically ventilated patients.

Plasma membrane stress failure in ventilator-injured lungs. A hypothesis about osmoregulation and the pharmacologic protection of the lungs against deformation injury.

Cell injury and repair are invariable consequences of mechanical ventilation with large tidal volumes. Rate and amplitude of deforming stress affect numerous cell metabolic functions including host defense and wound repair. Recently, we have focused on the role of plasma membrane stress failure as a trigger for a pro-inflammatory response in mechanically ventilated lungs. We have developed both cell- and organ-based models to study this problem. Alveolar epithelial cells that are exposed to deforming stresses seek to maintain sublytic plasma membrane tension and may activate mechanisms of cell surface area regulation to control membrane tension. Interventions which either increase the amount of excess plasma membrane or enhance lipid trafficking should be cytoprotective against deformation induced injury. Osmotic manipulation may be one such intervention. Preconditioning the lungs with anisosmotic solutions may allow the cells to recruit excess plasma membrane and thus be more resistant to ventilator-induced lung injury.

Pneumothorax in pulmonary Langerhans cell histiocytosis.

BACKGROUND: Pulmonary Langerhans cell histiocytosis (PLCH) is a smoking-related interstitial lung disease characterized by development of cystic changes that predispose to occurrence of pneumothorax. STUDY OBJECTIVES: To determine the frequency, recurrence rate, and optimal management of pneumothorax associated with PLCH. DESIGN: Retrospective study. SETTING: Tertiary care, referral medical center. PATIENTS: One hundred two adults >or= 18 years old with histologically confirmed PLCH seen at Mayo Clinic Rochester over a 23-year period from 1976 to 1998. INTERVENTIONS: None. MEASUREMENTS AND RESULTS: Sixteen of 102 patients (16%) with PLCH had pneumothorax; mean age at the time of diagnosis was 29.4 years (range, 18 to 52 years), and all had smoked cigarettes. There were 37 episodes of pneumothoraces (1 to 5 episodes per patient); 10 patients (63%) had more than one episode. Median age at diagnosis of PLCH was significantly younger in patients with pneumothorax when compared to those without pneumothorax (27 years vs 41.5 years, p < 0.001), but pulmonary function parameters and survival after diagnosis were not significantly different. Rate of recurrent pneumothorax was 58% to the ipsilateral side when the episode was managed by observation or chest tube without pleurodesis, and 0% after surgical management with pleurodesis. CONCLUSIONS: These data support the early use of surgical therapy with pleurodesis in managing patients with PLCH and spontaneous pneumothorax.