Pseudomonas aeruginosa community-acquired pneumonia in previously healthy adults: case report and review of the literature

Gingival Necrosis Related to Sepsis-Induced Agranulocytosis Due to Pseudomonas aeruginosa Bacteraemia: A Case Report

Background: There have been no reports of sepsis-induced agranulocytosis causing gingival necrosis in otherwise medically healthy patients to the authors' best knowledge. Even though there are several case reports of gingival necrosis secondary to medication-induced agranulocytosis, they have not systematically described the natural progression of agranulocytosis-related gingival necrosis. Methods: This paper presents a case report of a 29-year-old female Indian patient with generalised gingival necrosis and constitutive signs of intermittent fever, nausea, and vomiting. She also complained of abdominal pains. Blood counts showed agranulocytosis, and the patient was admitted for a workup of the underlying cause. Parenteral broad-spectrum antibiotics were administered, which brought about clinical resolution. Results: Her gingival necrosis was attributed to sepsis-induced agranulocytosis triggered by Pseudomonas aeruginosa bacteraemia, and upon clinical recovery, spontaneous exfoliation left behind exposed bone. Secondary healing over the exposed alveolar bone was noted after a year-long follow-up, albeit with some residual gingival recession. Conclusions: Oral manifestations of gingival necrosis, when present with concomitant constitutive symptoms, could indicate a serious underlying systemic condition that could be potentially life-threatening if left untreated. Dentists should be cognizant of this possibility so that timely intervention is not delayed.

Multi-drug resistant Pseudomonas aeruginosa: a 2019-2020 single center retrospective case control study

Multi-drug resistance in the post COVID-19 world is a growing concern. The objective of this study was to describe temporal trends and explore independent risk factors for the isolation of multi-drug resistant (MDR) P. aeruginosa.

Methods

This was a retrospective case-control study of patients with P. aeruginosa isolates recovered from January 2019 to December 2020. MDR P. aeruginosa was defined as non-susceptibility to at least one agent in three or more anti-pseudomonal antimicrobial categories.

Results

In total, 258 unique isolates were identified. Prolonged hospitalization (P<0.001), prior antibiotic use (P<0.001), and respiratory sources (P<0.001) were strongly associated with the presence of MDR P. aeruginosa. From 2019 to 2020, there was a decrease in the total number of P. aeruginosa isolates but a significant increase in the proportion of MDR P. aeruginosa isolates (P=0.015).

Conclusions

Over a period that coincided with the COVID-19 pandemic, there was an increased proportion of MDR P. aeruginosa isolates from hospitalized patients. Improved identification of patients at risk for MDR P. aeruginosa could facilitate appropriate empiric antibiotic decisions like dual anti-pseudomonal therapy. The features of the COVID-19 outbreak that had a severe impact on patient care and that may have affected drug resistance in other respiratory pathogens should be explored.

A Fatal Case of Pseudomonas aeruginosa Community-Acquired Pneumonia in an Immunocompetent Patient: Clinical and Molecular Characterization and Literature Review

Rare cases of Pseudomonas aeruginosa community-acquired pneumonia (PA-CAP) were reported in non-immunocompromised patients. We describe a case of Pseudomonas aeruginosa (PA) necrotizing cavitary CAP with a fatal outcome in a 53-year-old man previously infected with SARS-CoV-2, who was admitted for dyspnea, fever, cough, hemoptysis, acute respiratory failure and a right upper lobe opacification. Six hours after admission, despite effective antibiotic therapy, he experienced multi-organ failure and died. Autopsy confirmed necrotizing pneumonia with alveolar hemorrhage. Blood and bronchoalveolar lavage cultures were positive for PA serotype O:9 belonging to ST1184. The strain shares the same virulence factor profile with reference genome PA01. With the aim to better investigate the clinical and molecular characteristics of PA-CAP, we considered the literature of the last 13 years concerning this topic. The prevalence of hospitalized PA-CAP is about 4% and has a mortality rate of 33-66%. Smoking, alcohol abuse and contaminated fluid exposure were the recognized risk factors; most cases presented the same symptoms described above and needed intensive care. Co-infection of PA-influenza A is described, which is possibly caused by influenza-inducing respiratory epithelial cell dysfunction: the same pathophysiological mechanism could be assumed with SARS-CoV-2 infection. Considering the high rate of fatal outcomes, additional studies are needed to identify sources of infections and new risk factors, along with genetic and immunological features. Current CAP guidelines should be revised in light of these results.

Young Healthy Patient With Severe COVID-19 and Fulminant Community-Acquired Pseudomonas aeruginosa Pneumonia: A Case Report

Community-acquired pneumonia (CAP) caused by Pseudomonas aeruginosa in healthy adults can rapidly lead to severe outcomes. We treated a case of P. aeruginosa-induced CAP and concurrent severe coronavirus disease (COVID-19) in a healthy 39-year-old man without other serious risk factors for severe illness except smoking. Immediately after admission, the patient developed sepsis and received intensive broad-spectrum antibacterial therapy with meropenem and vancomycin, veno-arterial extracorporeal membrane oxygenation (VAECMO), and catecholamine supplementation. Despite receiving multidisciplinary treatment, the patient died within 24 hours. P. aeruginosa with normal antimicrobial susceptibility was identified in blood and sputum cultures of samples taken at admission. Gram staining of the bacteria detected in blood cultures was suspicious for non-glucose-fermenting Gram-negative rods, including P. aeruginosa, and the antimicrobial regimen that was initiated following admission was considered effective. The patient was a plumber and a smoker, which are risk factors for P. aeruginosa-induced CAP, and the clinical course matched those in previous reports of P. aeruginosa-induced CAP, including necrotizing pneumonia with cavities and rapid progression of sepsis. Although COVID-19 can be the sole cause of septic shock, the combination of P. aeruginosa bacteremia and COVID-19 was possibly the cause of septic shock in this case. Even during an infectious disease pandemic, reviewing the patient's occupational history and comorbidities and performing blood and sputum culture tests, including Gram staining, are important for the provision of appropriate treatment.

Fulminant psudeumonas pneumonia following coronary artery bypass grafting - Case report

INTRODUCTION AND IMPORTANCE

Pneumonia has always been a source of complication after surgeries. Pseudomonas aeruginosa has emerged as one of the most problematic Gram-negative pathogens among nosocomial infections. Pneumonia caused by pseudomonas is usually slowly progressive allowing clinicians to detect and manage it on time.

CLINICAL PRESENTATION

A 55-year-old man was hospitalized for elective CABG, complicated by fulminant pneumonia. Vancomycin and meropenem were adminestered as soon as the symptoms appeared. However, the patient died from septic shock syndrome caused by pseudomonas pneumonia on the third postoperative day, just hours after the first symptom appeared. The chest X-ray showed an extreme opacity within less than 12 h.

CLINICAL DISCUSSION

This case is reported because of its rare clinical presentation of Fulminant pseudomonas pneumonia following cardiac surgery.

CONCLUSION

Consider pseudomonas aeruginosa as a certain cause of pneumonia after cardiac surgery, and an organized, modified guideline is needed to determine the best option and timeline for treating this complication.

Pseudomonas aeruginosa Pneumonia: Evolution of Antimicrobial Resistance and Implications for Therapy

Pseudomonas aeruginosa (PA), a non-lactose-fermenting gram-negative bacillus, is a common cause of nosocomial infections in critically ill or debilitated patients, particularly ventilator-associated pneumonia (VAP), and infections of urinary tract, intra-abdominal, wounds, skin/soft tissue, and bloodstream. PA rarely affects healthy individuals, but may cause serious infections in patients with chronic structural lung disease, comorbidities, advanced age, impaired immune defenses, or with medical devices (e.g., urinary or intravascular catheters, foreign bodies). Treatment of pseudomonal infections is difficult, as PA is intrinsically resistant to multiple antimicrobials, and may acquire new resistance determinants even while on antimicrobial therapy. Mortality associated with pseudomonal VAP or bacteremias is high (> 35%) and optimal therapy is controversial. Over the past three decades, antimicrobial resistance (AMR) among PA has escalated globally, via dissemination of several international multidrug resistant "epidemic" clones. We discuss the importance of PA as a cause of pneumonia including health care-associated pneumonia, hospital-acquired pneumonia, VAP, the emergence of AMR to this pathogen, and approaches to therapy (both empirical and definitive).

Virulent Pseudomonas aeruginosa pneumonia in an immunocompetent adult associated with a home whirlpool bath: A case report

We present a case of life-threatening pneumonia caused by Pseudomonas aeruginosa (P. aeruginosa) in a healthy 67-year-old man. Rapid disseminated infection resulted in the right hemorrhagic pneumonia and bacteremia. Antimicrobial therapy had limited effects, radical pneumonectomy eventually resolved the prolonged infection. Concurrently, we explored the environmental factors responsible for fulminant P. aeruginosa infection. Multi-locus sequence typing demonstrated that P. aeruginosa isolated from the patient was identical to that collected from home whirlpool bath by the common virulent factor gene. Massive inhalation of contaminated aerosol and pathogen virulence may have synergistically contributed to the severity in this case.

Evaluation of Selected Parameters of the Specific Immune Response against Pseudomonas aeruginosa Strains

The immune response to Pseudomonas aeruginosa strains could be influenced by differences in antibiotic resistance and virulence. At the present time, it is unclear which type of immune responses enables uncontrolled invasion of opportunistic pathogens. The conditional pathogenicity of Pseudomonas aeruginosa served as an inspiration to begin a study on this bacterium. The aim of this study was to gain insight into selected parameters describing immune responses with regards to the adaptable agents of this pathogen. For the analysis of the specific immune response, the potential of Pseudomonas aeruginosa to stimulate lymphocytes, including Th17 lymphocytes, dendritic cells and other components of the adaptive immune response, was examined. The highest percentage of CD83+CD1a-HLA-DR++ cells was found after stimulation with lysates of strains isolated from the patients with severe systemic infection. We found statistically significant differences in percentages of HLA-DR+ PBMCs and MFI of HLA-DR between groups of Pseudomonas aeruginosa strains isolated from the patients with different clinical courses of infection. Our results suggest that the clinical course and outcomes of Pseudomonas aeruginosa infections are not associated with impairment of the specific immune response.

Combination Therapy of Polymyxin B and Amikacin for Community-Acquired Pseudomonas aeruginosa Pneumonia with MODS in a Previously Healthy Patient: A Case Report

Background

Pseudomonas aeruginosa (P. aeruginosa) is an uncommon but fatal causative pathogen for community-acquired pneumonia (CAP). Few case reports described the previously healthy individuals with CAP caused by P. aeruginosa.

Case Presentation

A 67-year-old male farmer was referred to our hospital with a 6-day history of fever and shortness of breath. The radiologic findings revealed a dense consolidation site in the right lung, considering infection lesion, accompanying with mediastinal and right hilar lymphadenopathy. Sputum sample results showed P. aeruginosa and multidrug-resistant Acinetobacter baumannii. The combination of polymyxin B and amikacin was given to him based on the lab results, the manifestations of the patient were alleviated and he returned to his home after a 35-day hospitalization.

Conclusion

We need to keep close attention to community-acquired P. aeruginosa pneumonia due to its high mortality, further studies are needed to identify the infectious source, effective examination, and optimal therapy including medications and duration.

Establishment and Characterization of Bacterial Infection of Breast Implants in a Murine Model

BACKGROUND

Staphylococcus epidermidis and Pseudomonas aeruginosa are the most common causes of Gram-positive and Gram-negative breast implant-associated infection. Little is known about how these bacteria infect breast implants as a function of implant surface characteristics and timing of infection.

OBJECTIVES

The aim of this work was to establish a mouse model for studying the impact of various conditions on breast implant infection.

METHODS

Ninety-one mice were implanted with 273 breast implant shells and infected with S. epidermidis or P. aeruginosa. Smooth, microtextured, and macrotextured breast implant shells were implanted in each mouse. Bacterial inoculation occurred during implantation or 1 day later. Implants were retrieved 1 or 7 days later. Explanted breast implant shells were sonicated, cultured, and colony-forming units determined or analyzed with scanning electron microscopy.

RESULTS

P. aeruginosa could be detected on all device surfaces at 1- and 7- days post infection (dpi), when mice were implanted and infected concurrently or when they were infected 1- day after implantation. However, P. aeruginosa infection was more robust on implant shells retrieved at 7 dpi and particularly on the macrotextured devices that were infected 1 day post implantation. S. epidermidis was mostly cleared from implants when mice were infected and implanted concurrently. Other the other hand, S. epidermidis could be detected on all device surfaces at 1 dpi and 2 days post implantation. However, S. epidermdis infection was suppressed by 7 dpi and 8 days post implantation.

CONCLUSIONS

S. epidermidis required higher inoculating doses to cause infection and was cleared within 7 days. P. aeruginosa infected at lower inoculating doses, with robust biofilms noted 7 days later.

Necrotizing pneumonia (aetiology, clinical features and management)

PURPOSE OF REVIEW

Necrotizing pneumonia is a severe form of community-acquired pneumonia characterized by rapid progression of consolidation to necrosis and cavitation which may lead to pulmonary gangrene. Morbidity and mortality are high and chronic sequelae are frequent. The lack of guidance supports the review of the latest recommendations in the management of these pneumonias.

RECENT FINDINGS

Antibiotic therapy alone may not be enough to alter the course of the infection, and regimens, adjunctive therapies like intravenous immunoglobulins, surgery may be required to alter the course of the disease especially with pulmonary gangrene.

SUMMARY

The causative agents, clinical features and management of necrotizing pneumonias are discussed.

Isolation and characterization of bacteriophage to control multidrug-resistant Pseudomonas aeruginosa planktonic cells and biofilm

Pseudomonas aeruginosa is Gram-negative bacterium, one of the leading cause of drug-resistant nosocomial infections in developing countries. This bacterium possesses chromosomally encoded efflux pumps, poor permeability of outer-membrane and high tendency for biofilm formation which are tools to confer resistance. Bacteriophages are regarded as feasible treatment option for control of resistant P. aeruginosa. The aim of the current study was isolate and characterized a bacteriophage against P. aeruginosa with MDR and biofilm ability. A bacteriophage MA-1 with moderate host range was isolated from waste water. The phage was considerable heat and pH stable. Electron microscopy revealed that phage MA-1 belongs to Myoviridae family. Its genome was dsDNA (≈50 kb), coding for eighteen different proteins (ranging from 12 to 250 KDa). P. aeruginosa-2949 log growth phase was significantly reduced by phage MA-1 (2.5 × 10³ CFU/ml) as compared to control (without phage). Phage MA-1 also showed significant reductions of 2.0, 2.5 and 3.2 folds in 24, 48, and 74 h old biofilms after 6 h treatment with phage respectively as compared to control. It was concluded from this study that phage MA-1 has capability of killing P. aeruginosa planktonic cells and biofilm, but for complete eradication cocktail will more effective to avoid resistance.

Intranasal Peptide-Based FpvA-KLH Conjugate Vaccine Protects Mice From Pseudomonas aeruginosa Acute Murine Pneumonia

Pseudomonas aeruginosa is an opportunistic pathogen causing acute and chronic respiratory infections associated with morbidity and mortality, especially in patients with cystic fibrosis. Vaccination against P. aeruginosa before colonization may be a solution against these infections and improve the quality of life of at-risk patients. To develop a vaccine against P. aeruginosa, we formulated a novel peptide-based P. aeruginosa subunit vaccine based on the extracellular regions of one of its major siderophore receptors, FpvA. We evaluated the effectiveness and immunogenicity of the FpvA peptides conjugated to keyhole limpet hemocyanin (KLH) with the adjuvant curdlan in a murine vaccination and challenge model. Immunization with the FpvA-KLH vaccine decreased the bacterial burden and lung edema after P. aeruginosa challenge. Vaccination with FpvA-KLH lead to antigen-specific IgG and IgM antibodies in sera, and IgA antibodies in lung supernatant. FpvA-KLH immunized mice had an increase in recruitment of CD11b⁺ dendritic cells as well as resident memory CD4⁺ T cells in the lungs compared to non-vaccinated challenged mice. Splenocytes isolated from vaccinated animals showed that the FpvA-KLH vaccine with the adjuvant curdlan induces antigen-specific IL-17 production and leads to a Th17 type of immune response. These results indicate that the intranasal FpvA-KLH conjugate vaccine can elicit both mucosal and systemic immune responses. These observations suggest that the intranasal peptide-based FpvA-KLH conjugate vaccine with curdlan is a potential vaccine candidate against P. aeruginosa pneumonia.

Reverse QMRA as a Decision Support Tool: Setting Acceptable Concentration Limits for Pseudomonas aeruginosa and Naegleria fowleri

Opportunistic premise plumbing pathogens such as Pseudomonas aeruginosa and Naegleria fowleri are a growing concern in building water systems because of their potential risks to human health. The aim of this study was to determine the critical concentrations of P. aeruginosa and N. fowleri in water that are associated with meaningful public health risks. To determine these concentrations, a reverse quantitative microbial risk assessment (QMRA) was conducted. Environmental concentrations of P. aeruginosa and N. fowleri corresponding to the risk target of one micro-disability-adjusted life year (DALY) per person per year and 10−4 annual risks of illness were calculated for several applicable exposure scenarios. To calculate the concentration of P. aeruginosa, cleaning contact lenses with potentially contaminated tap water in the absence of an appropriate cleaning solution was considered. For N. fowleri, two exposure scenarios, recreational exposure (swimming) and nasal cleansing (via the use of a neti pot™ or similar device) were considered. The highest critical concentration for P. aeruginosa was found to be 33 CFU/L with a 95% confidence interval of (2.0, 118) for the drop exposure scenario using the 10−4 annual risk target. For N. fowleri, based on the DALY approach, critical concentrations were 0.000030 N. fowleri/L for swimming and 0.00000060 N. fowleri/L for neti pot™ use scenario. Considering heat inactivation, the critical concentration limits for P. aeruginosa using the DALY approach and the 10−4 annual risk target approach were found to be 0.55 CFU/L and 55 CFU/L, respectively. For N. fowleri, the 10−4 annual risk target approach resulted in 0.022 N. fowleri/L and the DALY approach resulted in 0.00000064 N. fowleri/L for the neti pot™ scenario. For P. aeruginosa, N50 (the median infective dose) and alpha (α) contributed the most and contact rates the least to the variability and uncertainty of the estimates for all the scenarios. For N. fowleri, N50 and contact rates contributed the most and α the least to the variability and uncertainty to calculate the concentrations for all the scenarios. The QMRA framework implemented in this research can be used to incorporate more information regarding opportunistic pathogens to inform management decisions, and to prioritize the best interventions regarding estimated reduction in infections caused by opportunistic pathogens.

Septic shock secondary to an acute necrotizing community-acquired pneumonia with bacteremia due to Pseudomonas aeruginosa

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Necrotizing acute community-acquired pneumonia due to Pseudomonas aeruginosa are rare.

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Second description of a septic shock secondary to a necrotizing CAP with bacteremia due to P. aeruginosa for which pulmonary origin was proven by bronchoalveolar lavage fluid on a patient who survived.

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Anti-pseudomonal monotherapy may be may be a better option for older patients

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Despite risk factors related to the host or to the bacteria, the evolution remains unpredictable.

Pseudomonas aeruginosa is an uncommon cause of necrotizing acute community-acquired pneumonia (CAP). Only thirteen cases have been previously reported in the literature. In this article, we describe a case of previously healthy 80-year-old male patient, who presented in septic shock caused by necrotizing CAP. Despite inadequate empiric antimicrobial treatment, the patient survived and was able to return to his home after three weeks of hospitalization. To the best of our knowledge, this is the second case of septic shock secondary to P. aeruginosa necrotizing CAP and bacteremia, with optimal clinical outcome. We highlight the evolution of this pathology remains unpredictable, despite the factors related to the host and the bacterium.

Complex bacterial flora of imported pet tortoises deceased during quarantine: Another zoonotic threat?

Turtoises are a great puzzle when it comes to their bacterial flora, the composition and structure of which are still unknown in details. Its component which has been best described so far is Salmonella spp., presumably due to the threat of reptile-associated salmonellosis in humans. This investigation tried to assess and characterize intestinal bacterial flora of imported tortoises found dead during quarantine. Most of the animals carried various serovars of Salmonella showing no antimicrobial resistance. Presence of multiresistant Escherichia coli was possibly a result of industrial breeding and high usage of antimicrobials. Thirteen bacterial species or genera like Citrobacter spp., Morganella spp., Pseudomonas spp. were identified. Their commensal character is assumed, although pathogenic potential might be verified. The results indicate global tortoise trade as a source of common and exotic bacteria or antimicrobial resistance mechanisms in new geographical areas. These dangers indicate the need for a systematic survey of exotic pets and establishment of legal requirements for reptile health conditions on breeding, trade premises and in households with such pets.

A case report of community-acquired Pseudomonas aeruginosa pneumonia complicated with MODS in a previously healthy patient and related literature review

Background

Pseudomonas aeruginosa is an unusual pathogen in community-acquired pneumonia, especially in previously healthy adults, but often indicates poor prognosis.

Case presentation

We report a previously healthy patient who developed severe community-acquired pneumonia (CAP) caused by P. aeruginosa. He deteriorated to septic shock and multiple organ dysfunction syndrome (MODS) quickly, complicated by secondary hematogenous central nervous system (CNS) infection. After 1 month of organ support and antipseudomonal therapy, he had significant symptomatic improvement and was discharged from hospital. During treatment, the pathogen developed resistance to carbapenems quickly and the antibiotic regimen was adjusted accordingly.

Conclusions

According to our case and related literature review, we conclude that more attention should be paid to community-acquired Pseudomonas aeruginosa pneumonia, because of its rapid progression and poor prognosis.

A bacterial biosensor encoding a genetically modified LuxR receptor exhibits improved detection of Pseudomonas aeruginosa's biomarker molecule 2-aminoacetophenone

2-Aminoacetophneone (2-AA) is a volatile molecule produced in high amounts by the opportunistic pathogen Pseudomonas aeruginosa. We have previously shown that 2-AA activates the quorum sensing (QS) LuxR receptor of Aliivibrio fischeri. In the present study we were able to improve LuxR's affinity and detection limit for 2-AA by genetic modification of three amino acids within the binding pocket of the receptor. Expression of the modified LuxR receptor in a luminescent bacterial biosensor provided an efficient detection assay of 2-AA in clinical P. aeruginosa strains isolated from blood and lung infections, as well as in phlegm samples obtained from subjects suffering from lung infections.

Community-acquired necrotizing pneumonia with bacteremia caused by Pseudomonas aeruginosa in a patient with emphysema: An autopsy case report

We report the case of a 47-year-old man with chronic obstructive pulmonary disease who was referred to our hospital for acute dyspnea. The radiologic findings revealed consolidation with a cavity in the left upper lobe of the lung. Blood/sputum cultures detected Pseudomonas aeruginosa. Despite intensive care, the patient died from respiratory failure. Autopsy revealed multiple small necrotizing cavities that had coalesced. Although P. aeruginosa is a known causative pathogen of community-acquired pneumonia in patients with structural lung disease, the radiologic findings were non-specific. Irrespective of imaging findings, P. aeruginosa should be considered a cause of community-acquired pneumonia.

Community-Acquired Cavitary Pseudomonas Pneumonia Linked to Use of a Home Humidifier

Pseudomonas aeruginosa is an opportunistic pathogen that rarely causes pneumonia in otherwise healthy patients. We describe a case of community-acquired P. aeruginosa pneumonia in a previously healthy individual who likely acquired the infection from a home humidifier.

Necrotizing Pseudomonas aeruginosa Community-Acquired Pneumonia: A Case Report and Review of the Literature

Lung cavities are not typically associated with community-acquired pneumonia (CAP). CAP due to P. aeruginosa is rare and even less commonly causes necrotizing pneumonia. We report a case of P. aeruginosa CAP that progressed to necrotizing pneumonia and was eventually fatal. Procalcitonin (PCT) has been well investigated in guiding antibiotic therapy (especially CAP) in adults. In this case, PCT at presentation and sequentially was negative. We discuss this caveat and present hypotheses as to the sensitivity and specificity of PCT and C-reactive protein (CRP) in these patients. To better characterize P. aeruginosa CAP, we undertook a review of cases indexed in PubMed from 2001 to 2016 (n = 9). The data reveal that risk factors for P. aeruginosa CAP include smoking, alcohol use, obstructive lung disease, sinusitis, and hot tub use. The route of infection for P. aeruginosa CAP remains unknown. One of the most interesting findings on reviewing cases was that P. aeruginosa CAP involves the right upper lobe in the vast majority. We suggest that when physicians in the community see patients with distinctly upper lobe necrotizing or cavitary pneumonia, they should consider P. aeruginosa in their differential diagnosis. Further studies are needed to clarify route of infection, role of PCT and CRP, and optimal therapy including drug and duration.

Temporal Variations in Cigarette Tobacco Bacterial Community Composition and Tobacco-Specific Nitrosamine Content Are Influenced by Brand and Storage Conditions

Tobacco products, specifically cigarettes, are home to microbial ecosystems that may play an important role in the generation of carcinogenic tobacco-specific nitrosamines (TSNAs), as well as the onset of multiple adverse human health effects associated with the use of these products. Therefore, we conducted time-series experiments with five commercially available brands of cigarettes that were either commercially mentholated, custom-mentholated, user-mentholated, or non-mentholated. To mimic user storage conditions, the cigarettes were incubated for 14 days under three different temperatures and relative humidities (i.e., pocket, refrigerator, and room). Overall, 360 samples were collected over the course of 2 weeks and total DNA was extracted, PCR amplified for the V3V4 hypervariable region of the 16S rRNA gene and sequenced using Illumina MiSeq. A subset of samples (n = 32) was also analyzed via liquid chromatography with tandem mass spectrometry for two TSNAs: N'-nitrosonornicotine (NNN) and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK). Comparative analyses of the five tobacco brands revealed bacterial communities dominated by Pseudomonas, Pantoea, and Bacillus, with Pseudomonas relatively stable in abundance regardless of storage condition. In addition, core bacterial operational taxonomic units (OTUs) were identified in all samples and included Bacillus pumilus, Rhizobium sp., Sphingomonas sp., unknown Enterobacteriaceae, Pantoea sp., Pseudomonas sp., Pseudomonas oryzihabitans, and P. putida. Additional OTUs were identified that significantly changed in relative abundance between day 0 and day 14, influenced by brand and storage condition. In addition, small but statistically significant increases in NNN levels were observed in user- and commercially mentholated brands between day 0 and day 14 at pocket conditions. These data suggest that manufacturing and user manipulations, such as mentholation and storage conditions, may directly impact the microbiome of cigarette tobacco as well as the levels of carcinogens.

Risk factors for community-associated multidrug-resistant Pseudomonas aeruginosa in veterans with spinal cord injury and disorder: a retrospective cohort study

Study Design

Retrospective cohort study

Objectives

To identify independent risk factors associated with community-associated multidrug resistant P. aeruginosa (MDRPA) in a population of Veterans with spinal cord injury and disorders (SCI/D).

Setting

127 Veterans Affairs healthcare facilities

Methods

Laboratory results from January 1, 2012 to December 31, 2013 were collected and MDRPA cultures were compared to non-MDRPA cultures.

Results

One thousand four hundred forty one cultures were collected from Veterans with SCI/D, including 227 cultures with MDRPA isolates. Characteristics associated with an increased odds of MDRPA include age 50-64 (aOR= 1.80, 95% CI= 1.13-2.87), MDRPA culture in the past 365 days (aOR= 9.12, 95% CI= 5.88-14.15), and carbapenem exposure in the past 90 days (aOR= 2.56, 95% CI= 1.35-4.87). In contrast, paraplegia was associated with a 53% decreased odds of MDRPA compared to those with tetraplegia (aOR= 0.47, 95% CI= 0.32-0.69).

Conclusions

Risk factors for community-associated MDRPA include prior history of MDRPA and exposure to carbapenems. Awareness of these factors is important for targeted prevention and treatment of MDRPA in patients with SCI/D.

Septic Pulmonary Embolism Requiring Critical Care: Clinicoradiological Spectrum, Causative Pathogens and Outcomes

OBJECTIVES:

Septic pulmonary embolism is an uncommon but life-threatening disorder. However, data on patients with septic pulmonary embolism who require critical care have not been well reported. This study elucidated the clinicoradiological spectrum, causative pathogens and outcomes of septic pulmonary embolism in patients requiring critical care.

METHODS:

The electronic medical records of 20 patients with septic pulmonary embolism who required intensive care unit admission between January 2005 and December 2013 were reviewed.

RESULTS:

Multiple organ dysfunction syndrome developed in 85% of the patients, and acute respiratory failure was the most common organ failure (75%). The most common computed tomographic findings included a feeding vessel sign (90%), peripheral nodules without cavities (80%) or with cavities (65%), and peripheral wedge-shaped opacities (75%). The most common primary source of infection was liver abscess (40%), followed by pneumonia (25%). The two most frequent causative pathogens were Klebsiella pneumoniae (50%) and Staphylococcus aureus (35%). Compared with survivors, nonsurvivors had significantly higher serum creatinine, arterial partial pressure of carbon dioxide, and Acute Physiology and Chronic Health Evaluation II and Sequential Organ Failure Assessment scores, and they were significantly more likely to have acute kidney injury, disseminated intravascular coagulation and lung abscesses. The in-hospital mortality rate was 30%. Pneumonia was the most common cause of death, followed by liver abscess.

CONCLUSIONS:

Patients with septic pulmonary embolism who require critical care, especially those with pneumonia and liver abscess, are associated with high mortality. Early diagnosis, appropriate antibiotic therapy, surgical intervention and respiratory support are essential.

Microbial Etiology of Community-Acquired Pneumonia Among Infants and Children Admitted to the Pediatric Hospital, Ain Shams University

Background

While recognizing the etiology of community-acquired pneumonia is necessary for formulating local antimicrobial guidelines, limited data is published about this etiology in Egyptian pediatric patients.

Objectives

To determine the frequency of bacterial and viral pathogens causing community-acquired pneumonia (CAP) among immunocompetent Egyptian infants and preschool children.

Methods

Ninety infants and preschool-age children admitted to our hospital with CAP were prospectively included in the study. Etiological agents were identified using conventional bacteriological identification methods and IgM antibodies detection against common atypical respiratory bacteria and viruses.

Results

An etiology was identified in 59 patients (65.5%). Bacterial pathogens were detected in 43 (47.8%) of the cases while viral pathogens were detected in 23 (25.5%). Coinfection with more than one etiologic agent was evident in seven patients (7.8%). The most common typical bacterial cause of pneumonia was Staphylococcus aureus (n = 12, 13.3%), followed by Streptococcus pneumoniae and Klebsiella pneumoniae (n = 7, 7.8%, each). The commonest atypical bacterium was Mycoplasma pneumoniae (n = 10, 11.1%), whereas the commonest viral etiology was influenza viruses (n = 11, 12.2%).

Conclusion

Although we could not determine the causative agent in some studied cases, this study provides preliminary data regarding the spectrum and frequency of microorganisms causing CAP in Egyptian infants and preschool children.

Virulence Attributes and Host Response Assays for Determining Pathogenic Potential of Pseudomonas Strains Used in Biotechnology

Pseudomonas species are opportunistically pathogenic to humans, yet closely related species are used in biotechnology applications. In order to screen for the pathogenic potential of strains considered for biotechnology applications, several Pseudomonas strains (P.aeruginosa (Pa), P.fluorescens (Pf), P.putida (Pp), P.stutzeri (Ps)) were compared using functional virulence and toxicity assays. Most Pa strains and Ps grew at temperatures between 28°C and 42°C. However, Pf and Pp strains were the most antibiotic resistant, with ciprofloxacin and colistin being the most effective of those tested. No strain was haemolytic on sheep blood agar. Almost all Pa, but not other test strains, produced a pyocyanin-like chromophore, and caused cytotoxicity towards cultured human HT29 cells. Murine endotracheal exposures indicated that the laboratory reference strain, PAO1, was most persistent in the lungs. Only Pa strains induced pro-inflammatory and inflammatory responses, as measured by elevated cytokines and pulmonary Gr-1 -positive cells. Serum amyloid A was elevated at ≥ 48 h post-exposure by only some Pa strains. No relationship was observed between strains and levels of peripheral leukocytes. The species designation or isolation source may not accurately reflect pathogenic potential, since the clinical strain Pa10752 was relatively nonvirulent, but the industrial strain Pa31480 showed comparable virulence to PAO1. Functional assays involving microbial growth, cytotoxicity and murine immunological responses may be most useful for identifying problematic Pseudomonas strains being considered for biotechnology applications.

Pseudomonas aeruginosa Bacteremia among Immunocompetent and Immunocompromised Patients: Relation to Initial Antibiotic Therapy and Survival

Pseudomonas aeruginosa bacteremia occurs mainly in immunocompromised patients. However, P. aeruginosa bacteremia in immunocompetent patients has also been reported. The aim of this study was to evaluate the clinical characteristics of P. aeruginosa bacteremia in relation to the immune status of the patients. The medical records of 126 adult patients with P. aeruginosa bacteremia in Nagasaki University Hospital were retrospectively reviewed between January 2003 and December 2012. Of 126 patients with P. aeruginosa bacteremia, 60 patients (47.6%) were classified as immunocompetent. Mortality in immunocompetent patients tended to be lower than in immunocompromised patients (7-day mortality, 8% vs. 30%, P < 0.01; 30-day mortality, 23% vs. 39%, P = 0.053). Multivariate analysis showed that a higher sequential organ failure assessment score (hazard ratio [HR]: 1.27, P < 0.01) and underlying malignancies (HR: 3.33, P < 0.01) were independently associated with 30-day mortality. Initial antibiotic therapy (HR: 0.21, P < 0.01) and patients' immune status (HR: 0.29, P = 0.02) also had a significant impact on survival. However, there was a significant interaction between these 2 variables (P = 0.03 for interaction). A subgroup analysis showed that in immunocompromised, but not immunocompetent patients, initial appropriate antibiotic therapy was associated with lower mortality (30-day mortality 20.5% vs. 66.7%, P < 0.01 by log-rank test).

Community-acquired lobar pneumonia caused by Pseudomonas aeruginosa infection in Japan: a case report with histological and immunohistochemical examination

Pseudomonas aeruginosa is a common pathogen in nosocomial and/or healthcare-associated pneumonia, but is rare in community-acquired pneumonia. A 50-year-old previously healthy woman was taken to the emergency department because of rapidly progressing dyspnea. Chest radiograph showed consolidation of the entire right upper lobe, a finding suggestive of lobar pneumonia. The patient died of respiratory failure with bronchial bleeding, on the same day of admission. Autopsy revealed that the alveoli throughout the upper right lobe were filled with dense inflammatory cells mainly consisting of macrophages and neutrophils. Immunoreactive bacilli by using an anti-P. aeruginosa antibody were localized within macrophages accumulated in the alveoli as well in the vessel walls. Lobar pneumonia composed of dense neutrophils and bacteria-laden macrophages with total lung congestion and edema may be characteristic for community-acquired P. aeruginosa pneumonia in a healthy adult.

[Two Cases of Rapidly Progressive Community-acquired Pneumonia Due to Pseudomonas aeruginosa]

Pseudomonas aeruginosa is a significant causative bacterium in hospital-acquired pneumonia and nursing and healthcare-associated pneumonia, but it seems to be rare in community-acquired pneumonia (CAP). We report two cases of severe CAP due to P. aeruginosa. Case 1: A 52-year-old man was referred to our hospital for chest and back pain. He was being treated for diabetes mellitus and had a long history of smoking. Chest images showed consolidation in the right upper lobe. Soon after hospitalization, he developed sepsis shock and died seven hours later. Case 2: A 73-year-old man with a history of heavy smoking was referred to our hospital for right chest pain. Chest images showed right upper lobe pneumonia. Although wide-spectrum antimicrobial agents were administrated, he died ten hours after admission. In both cases, there was a rapid progression to death, despite administration of a broad spectrum of antibiotics and treatment for sepsis. In cases of CAP involving the right upper lobe, the possibility of bacteremia and rapid progress should be considered.

Community-acquired Pseudomonas aeruginosa-pneumonia in a previously healthy man occupationally exposed to metalworking fluids

Although the Pseudomonas aeruginosa infection is well known and frequently found in hospitals and nursing care facilities, many cases are also reported outside these boundaries. In general, this pathogen infects debilitated patients either by comorbidities or by any form of immunodeficiency. In cases of respiratory infection, tobacco abuse seems to play an important role as a risk factor. In previously healthy patients, community-acquired pneumonia (CAP) with P. aeruginosa as the etiological agent is extremely rare, and unlike the cases involving immunocompromised or hospitalized patients, the outcome is severe, and is fatal in up to 61.1% of cases. Aerosolized contaminated water or solutions are closely linked to the development of respiratory tract infection. In this setting, metalworking fluids used in factories may be implicated in CAP involving previously healthy people. The authors report the case of a middle-aged man who worked in a metalworking factory and presented a right upper lobar pneumonia with a rapid fatal outcome. P. aeruginosa was cultured from blood and tracheal aspirates. The autopsy findings confirmed a hemorrhagic necrotizing pneumonia with bacteria-invading vasculitis and thrombosis. A culture of the metalworking fluid of the factory was also positive for P. aeruginosa. The pulsed-field gel electrophoresis showed that both strains (blood culture and metalworking fluid) were genetically indistinguishable. The authors highlight the occupational risk for the development of this P.aeruginosa-infection in healthy people.

Community-acquired, hospital-acquired, and healthcare-associated pneumonia caused by Pseudomonas aeruginosa

We describe three types of Pseudomonas aeruginosa pneumonia.

Case 1. P. aeruginosa was isolated from the blood and sputum of a 29-year-old male non-smoker who developed severe community-acquired pneumonia (CAP). Piperacillin was initially effective, but fever and lobular pneumonia with cavities developed seven days after discharge. Intravenous piperacillin/tazobactam and tobramycin were administered for four weeks, followed by oral ciprofloxacin for two weeks. He finally recovered, but developed recurrent CAP due to P. aeruginosa despite appropriate antibiotic therapy and immunocompetent status.

Case 2. P. aeruginosa was isolated from the blood and sputum of a 57-year-old woman with renal cancer who developed hospital-acquired pneumonia (HAP) after surgical treatment. She recovered after meropenem administration for four weeks.

Case 3. A 67-year-old woman with systemic sclerosis and malignant lymphoma who was followed up on an outpatient basis underwent immunosuppressive therapy. Thereafter, she developed pneumonia and was admitted to our institution where P aeruginosa was isolated from blood and sputum samples. Healthcare-associated pneumonia (HCAP) was diagnosed and effectively treated with tobramycin and ciprofloxacin.

P. aeruginosa is not only a causative pathogen of HAP and HCAP, but possibly also of CAP.

Diversity of Antimicrobial Resistance and Virulence Determinants in Pseudomonas aeruginosa Associated with Fresh Vegetables

With the increased focus on healthy eating and consuming raw vegetables, this study assessed the extent of contamination of fresh vegetables by Pseudomonas aeruginosa in Jamaica and examined the antibiotic susceptibility profiles and the presence of various virulence associated determinants of P. aeruginosa. Analyses indicated that vegetables from retail markets and supermarkets were widely contaminated by P. aeruginosa; produce from markets were more frequently contaminated, but the difference was not significant. Lettuce and carrots were the most frequently contaminated vegetables, while tomatoes were the least. Pigment production (Pyoverdine, pyocyanin, pyomelanin and pyorubin), fluorescein and alginate were common in these isolates. Imipenem, gentamicin and ciprofloxacin were the most inhibitory antimicrobial agents. However, isolates were resistant or showed reduced susceptibility to ampicillin, chloramphenicol, sulphamethoxazole/trimethoprim and aztreonam, and up to 35% of the isolates were resistant to four antimicrobial agents. As many as 30% of the isolates were positive for the fpv1 gene, and 13% had multiple genes. Sixty-four percent of the isolates harboured an exoenzyme gene (exoS, exoT, exoU or exoY), and multiple exo genes were common. We conclude that P. aeruginosa is a major contaminant of fresh vegetables, which might be a source of infection for susceptible persons within the community.

Ultraviolet irradiation: An effective inactivation method of Aspergillus spp. in water for the control of waterborne nosocomial aspergillosis

Invasive aspergillosis is the second most common cause of nosocomial fungal infections and occurring mainly by Aspergillus fumigatus, Aspergillus flavus, and Aspergillus niger. There is evidence that nosocomial aspergillosis may be waterborne. This study was conducted to evaluate the ultraviolet (UV) irradiation efficiency in terms of inactivating the most important Aspergillus species in water since these are potential sources for nosocomial aspergillosis. A continuous flow UV reactor which could be used as a point-of-use (POU) system was used to survey Aspergillus inactivation by UV irradiation. The inactivation efficiency of UV fluence (4.15-25 mJ/cm(2)) was measured by determination of fungal density in water before and after radiation. Because turbidity and iron concentration are two major water quality factors impacting UV disinfection effectiveness, the potential influence of these factors on UV inactivation of Aspergillus spp. was also measured. The 4 log inactivation for A. fumigatus, A. niger and A. flavus at a density of 1000 cfu/ml was achieved at UV fluences of 12.45 mJ/cm(2), 16.6 mJ/cm(2) and 20.75 mJ/cm(2), respectively. The inactivation efficiency for lower density (100 cfu/ml) was the same as for the higher density except for A. flavus. The removal efficiency of Aspergillus spp. was decreased by increasing the turbidity and iron concentration. UV disinfection could effectively inactivate Aspergillus spores from water and eliminate potential exposure of high-risk patients to fungal aerosols by installation of POU UV systems.

Community acquired Pseudomonas pneumonia in an immune competent host

Pseudomonas aeruginosa is an uncommon cause of community-acquired pneumonia in immune-competent hosts. It is commonly seen in patients with structural lung abnormality such as cystic fibrosis or in immune compromised hosts. Here, the authors report a case of community-acquired Pseudomonas pneumonia in a 26-year old healthy man who presented with 8-week history of malaise and cough.

The role of whirlpool in wound care

Evidenced-based-wound management continues to be a cornerstone for advancing patient care. The purpose of this article is to review the use of whirlpool as a wound treatment in light of evidence, outcomes, and potential harm. Whirlpool was initially harnessed as a means to impart biophysical energy to a wound or burn to enhance mechanical debridement and cleansing. Other credible single-patient-use technologies which provide an alternative to whirlpool in wound care are presented.

Pseudomonas aeruginosa bacteremia upon hospital admission: risk factors for mortality and influence of inadequate empirical antimicrobial therapy

Pseudomonas aeruginosa is an uncommon cause of bacteremia upon hospital admission (UHA) and the chosen empirical antimicrobial therapy may not cover it appropriately. In a multicenter prospective study conducted in Israel, we evaluated risk factors for in-hospital mortality in patients with P. aeruginosa bacteremia UHA and determined the influence of delay in adequate empirical antimicrobial therapy on patients' outcome. Seventy-six adult patients with P. aeruginosa bacteremia within 72 h of hospital admission were included. Demographic, clinical, and treatment data were collected. Microbiological adequacy of empirical therapy was determined. Severe sepsis or septic shock at admission (OR, 21.9; P < 0.001), respiratory or unknown sources of bacteremia (OR, 11.5; P = 0.003), recent hospitalization (OR, 6.2; P = 0.032), and poor functional status (OR, 5.8; P = 0.029) were identified as independent predictors of mortality. Inadequate empirical antimicrobial therapy was marginally associated with increased mortality only among patients who presented with severe sepsis or septic shock (P = 0.051).

Fatal Pseudomonas aeruginosa pneumonia in a previously healthy woman was most likely associated with a contaminated hot tub

Community-acquired pneumonia due to Pseudomonas aeruginosa in previously healthy individuals is a rare disease that is associated with high fatality. On 14 February 2010 a previously healthy 49-year-old woman presented to an emergency room with signs and symptoms of pneumonia, 2 days after returning from a spa holiday in a wellness hotel. Blood cultures and respiratory specimens grew P. aeruginosa. Despite adequate antimicrobial therapy, the patient died of septic multiorgan failure on day nine of hospitalization. On February 26, nine water samples were taken from the hotel facilities used by the patient: In the hot tub sample 37,000 colony-forming units of P. aeruginosa/100 ml were detected. Two of five individual colonies from the primary plate used for this hot tub water sample were found to be genetically closely related to the patients’ isolates. Results from PFGE, AFLP and MLST analysis allowed the two lung isolates gained at autopsy and the whirlpool bathtub isolates to be allocated into one cluster. The patient most likely acquired P. aeruginosa from the contaminated water in the hotel’s hot tub. The detection of P. aeruginosa in high numbers in a hot tub indicates massive biofilm formation in the bath circulation and severe deficiencies in hygienic maintenance. The increasing popularity of hot tubs in hotels and private homes demands increased awareness about potential health risks associated with deficient hygienic maintenance.

Pseudomonas aeruginosa: host defence in lung diseases

Lung infections caused by the opportunistic pathogen Pseudomonas aeruginosa can present as a spectrum of clinical entities from a rapidly fatal pneumonia in a neutropenic patient to a multi-decade bronchitis in patients with cystic fibrosis. P. aeruginosa is ubiquitous in our environment, and one of the most versatile pathogens studied, capable of infecting a number of diverse life forms and surviving harsh environmental factors. It is also able to quickly adapt to new environments, including the lung, where it orchestrates virulence factors to acquire necessary nutrients, and if necessary, turn them off to prevent immune recognition. Despite these capabilities, P. aeruginosa rarely infects healthy human lungs. This is secondary to a highly evolved host defence mechanism that efficiently removes inhaled or aspirated pseudomonads. Many arms of the respiratory host defence have been elucidated using P. aeruginosa as a model pathogen. Human infections with P. aeruginosa have demonstrated the importance of the mechanical barrier functions including mucus clearance, and the innate immune system, including the critical role of the neutrophilic response. As more models of persistent or biofilm P. aeruginosa infections are developed, the role of the adaptive immune response will likely become more evident. Understanding the pathogenesis of P. aeruginosa, and the respiratory host defence response to it has, and will continue to, lead to novel therapeutic strategies to help patients.

Disseminated toxoplasmosis in an immunocompetent patient from Peruvian Amazon

We report a case of severe toxoplasmosis in an immunocompetent patient, characterized by pneumonia, retinochoroiditis, hepatitis and myositis. Diagnosis was confirmed by serology, T. gondii in thick blood smear and presence of bradyzoites in muscle biopsy. Treatment with pyrimethamine plus sulfadoxine was successful but visual acuity and hip extension were partially recovered. This is the first case report of severe toxoplasmosis in an immunocompetent patient from Peru.

Current treatment of pseudomonal infections in the elderly

Pseudomonas aeruginosa infections have emerged as a major infectious disease threat in recent decades as a result of the significant mortality of pseudomonal pneumonia and bacteraemia, and the evolving resistance exhibited by the pathogen to numerous antibacterials. Pseudomonas possesses a large genome; thus, the pathogen is environmentally adaptable, metabolically flexible, able to overcome antibacterial pressure by selecting for resistant strains and even able to accumulate resistance mechanisms, leading to multidrug resistance (MDR), an increasingly recognized therapeutic challenge. In fact, most research currently does not focus on maximizing the efficacy of available antibacterials; rather, it focuses on maximizing their ecological safety. The elderly population may be particularly prone to pseudomonal infection as a result of increased co-morbidities (such as diabetes mellitus and structural lung disease), the presence of invasive devices such as urinary catheters and feeding tubes, polypharmacy that includes antibacterials, and immune compromise related to age. However, age per se, as well as residence in nursing homes, may not predispose individuals to an increased risk for pseudomonal infection. On the other hand, age has been repeatedly outlined as a risk factor for MDR pseudomonal infections. The severity of pseudomonal infections necessitates prompt administration of appropriate antibacterials upon suspicion. Progress has been made in recognizing risk factors for P. aeruginosa infections both in hospitalized and community-residing patients. Antimicrobial therapy may be instituted as a combination or monotherapy: the debate cannot be definitively resolved since the available data are extracted from studies with varying targeted populations and varying definitions of response, adequacy and MDR. Empirical combination therapy maximizes the chances of bacterial coverage and exerts a lower resistance selection pressure. Although associated with increased percentages of adverse events, mainly as a result of the included aminoglycosides, empirical combination therapy seems a reasonable choice. Upon confirmation of Pseudomonas as the causative agent and awareness of its susceptibility profile, monotherapy is advocated by many, but not all, experts. Infections involving MDR strains can be treated with colistin, which has adequate efficacy and few renal adverse events, or doripenem. In the elderly, in addition to making dose modifications that are needed because of loss of renal function, the prescriber should be more cautious about the use of aminoglycoside-containing regimens, possibly replacing them with a combination of quinolone and a beta-lactam, notwithstanding the possible increased pressure for selection of resistance with the latter combination.

Risk factors and outcome of community-acquired pneumonia due to Gram-negative bacilli

BACKGROUND AND OBJECTIVE

Several sets of guidelines have advocated initial antibiotic treatment for community-acquired pneumonia due to Gram-negative bacilli in patients with specific risk factors. However, evidence to support this recommendation is scarce. We sought to identify risk factors for community-acquired pneumonia due to Gram-negative bacilli, including Pseudomonas aeruginosa, and to assess outcomes.

METHODS

An observational analysis was carried out on prospectively collected data for immunocompetent adults hospitalized for community-acquired pneumonia in two acute-care hospitals. Cases of pneumonia due to Gram-negative bacilli were compared with those of non-Gram-negative bacilli causes.

RESULTS

Sixty-one (2%) of 3272 episodes of community-acquired pneumonia were due to Gram-negative bacilli. COPD (odds ratio (OR) 2.4, 95% confidence interval (CI): 1.2-5.1), current use of corticosteroids (OR 2.8, 95% CI: 1.2-6.3), prior antibiotic therapy (OR 2.6, 95% CI: 1.4-4.8), tachypnoea >or=30 cycles/min (OR 2.1, 95% CI: 1.1-4.2) and septic shock at presentation (OR 6.1, 95% CI: 2.5-14.6) were independently associated with Gram-negative bacilli pneumonia. Initial antibiotic therapy in patients with pneumonia due to Gram-negative bacilli was often inappropriate. These patients were also more likely to require admission to the intensive care unit, had longer hospital stays, and higher early (<48 h) (21% vs 2%; P < 0.001) and overall mortality (36% vs 7%; P < 0.001).

CONCLUSIONS

These results suggest that community-acquired pneumonia due to Gram-negative bacilli is uncommon, but is associated with a poor outcome. The risk factors identified in this study should be considered when selecting initial antibiotic therapy for patients with community-acquired pneumonia.