Respiratory Infections In Immunocompromised Patients Research Articles

Phenotypic characterization of cryptic species in the fungal pathogen Histoplasma.

Histoplasmosis is an endemic mycosis that often presents as a respiratory infection in immunocompromised patients. Hundreds of thousands of new infections are reported annually around the world. The etiological agent of the disease, Histoplasma, is a dimorphic fungus commonly found in the soil where it grows as mycelia. Humans can become infected by Histoplasma through inhalation of its spores (conidia) or mycelial particles. The fungi transition into the yeast phase in the lungs at 37°C. Once in the lungs, yeast cells reside and proliferate inside alveolar macrophages. Genomic work has revealed that Histoplasma is composed of at least five cryptic phylogenetic species that differ genetically. Three of those lineages have received new names. Here, we evaluated multiple phenotypic characteristics (colony morphology, secreted proteolytic activity, yeast size, and growth rate) of strains from five of the phylogenetic species of Histoplasma to identify phenotypic traits that differentiate between these species: Histoplasma capsulatum sensu stricto, Histoplasma ohiense, Histoplasma mississippiense, Histoplasma suramericanum, and an African lineage. We report diagnostic traits for three species. The other two species can be identified by a combination of traits. Our results suggest that (i) there are significant phenotypic differences among the cryptic species of Histoplasma and (ii) those differences can be used to positively distinguish those species in a clinical setting and for further study of the evolution of this fungal pathogen.IMPORTANCEIdentifying species boundaries is a critical component of evolutionary biology. Genome sequencing and the use of molecular markers have advanced our understanding of the evolutionary history of fungal pathogens, including Histoplasma, and have allowed for the identification of new species. This is especially important in organisms where morphological characteristics have not been detected. In this study, we revised the taxonomic status of the four named species of the genus Histoplasma, H. capsulatum sensu stricto (ss), H. ohiense, H. mississippiense, and H. suramericanum, and propose the use of species-specific phenotypic traits to aid their identification when genome sequencing is not available. These results have implications not only for evolutionary study of Histoplasma but also for clinicians, as the Histoplasma species could determine the outcome of disease and treatment needed.

Utilizing a best practice advisory (BPA) to increase pneumocystis jirovecii pneumonia (PJP) prophylaxis prescribing for patients with cancer on high dose corticosteroids.

391 Background: Pneumocystis jirovecii pneumonia (PJP) is an opportunistic fungal infection that can cause severe respiratory infection in immunocompromised patients. Corticosteroid use is a common risk factor for developing PJP in non-human immunodeficiency virus (HIV) patients. Corticosteroids are commonly prescribed medications for cancer patients to help with symptom control from cancer treatment (e.g. nausea, vomiting, and pain) as well as for immunotherapy related adverse events. The risk of developing PJP is significantly increased for patients on prednisone equal to or greater than 20 mg per day x 1 month or equivalent. Steroid related PJP (srPJP) is associated with a 30-50% mortality in non-HIV patients. Methods: We conducted an IRB-approved retrospective chart review of individuals diagnosed with PJP at an academic medical center and 6 partner hospitals between 2016-2022. Patients were excluded if they had a diagnosis of HIV or prior hematopoietic stem cell transplant (HSCT). We then created a best practice advisory (BPA) built into the electronic health record to notify clinicians if a patient is at risk of developing srPJP based on their outpatient corticosteroid prescription. The BPA is triggered system-wide if a clinician signs an outpatient prescription for a prednisone or equivalent steroid dose of 20 mg or more for a duration of at least 3 weeks. The BPA will suggest PJP prophylaxis and link to an order for the clinician to select. Results: There were 96 identified cases of srPJP in non HIV/HSCT patients. None of these patients received antibiotic prophylaxis. Among these cases, 32 patients died from ARDS due to PJP, a mortality of 33.3%. 45% of identified cases were related to steroids prescribed for cancer management, and 68% of these received dexamethasone as the primary steroid. The BPA launched in April 2023 system wide across UC Health. Since launching the BPA in April 2023, it has been triggered 911 times with action taken by selecting an order for PJP prophylaxis 24.5% of the time. Conclusions: Despite the efficacy of prophylaxis, many patients at risk of developing srPJP do not receive prophylaxis. Since launching the BPA, preliminary data shows that the BPA has increased the orders placed for concurrent PJP prophylaxis. Further work must be done to determine if these orders for concurrent PJP prophylaxis were signed and if the BPA can increase PJP prophylaxis prescribing for patients on high dose corticosteroids and ultimately decrease srPJP cases and deaths.

Powerful and Real-Time Quantification of Antifungal Efficacy against Triazole-Resistant and -Susceptible Aspergillus fumigatus Infections in Galleria mellonella by Longitudinal Bioluminescence Imaging.

Aspergillus fumigatus is an environmental mold that causes life-threatening respiratory infections in immunocompromised patients. The plateaued effectiveness of antifungal therapy and the increasing prevalence of triazole-resistant isolates have led to an urgent need to optimize and expand the current treatment options. For the transition of in vitro research to in vivo models in the time- and resource-consuming preclinical drug development pipeline, Galleria mellonella larvae have been introduced as a valuable in vivo screening intermediate. Despite the high potential of this model, the current readouts of fungal infections in G. mellonella are insensitive, irreproducible, or invasive. To optimize this model, we aimed for the longitudinal quantification of the A. fumigatus burden in G. mellonella using noninvasive bioluminescence imaging (BLI). Larvae were infected with A. fumigatus strains expressing a red-shifted firefly luciferase, and the substrate dosage was optimized for the longitudinal visualization of the fungal burden without affecting larval health. The resulting photon flux was successfully validated for fungal quantification against colony forming units (CFU) analyses, which revealed an increased dynamic range from BLI detection. Comparison of BLI to survival rates and health index scores additionally revealed improved sensitivity for the early discrimination of differences in fungal burdens as early as 1 day after infection. This was confirmed by the improved detection of treatment efficacy against triazole-susceptible and -resistant strains. In conclusion, we established a refined G. mellonella aspergillosis model that enables the noninvasive real-time quantification of A. fumigatus by BLI. This model provides a quick and reproducible in vivo system for the evaluation of treatment options and is in line with 3Rs recommendations. IMPORTANCE Triazole-resistant Aspergillus fumigatus strains are rapidly emerging, and resistant infections are difficult to treat, causing mortality rates of up to 88%. The recent WHO priority list underscores A. fumigatus as one of the most critical fungal pathogens for which innovative antifungal treatment should be (urgently) prioritized. Here, we deliver a Galleria mellonella model for triazole-susceptible and -resistant A. fumigatus infections combined with a statistically powerful quantitative, longitudinal readout of the A. fumigatus burden for optimized preclinical antifungal screening. G. mellonella larvae are a convenient invertebrate model for in vivo antifungal screenings, but so far, the model has been limited by variable and insensitive observational readouts. We show that bioluminescence imaging-based fungal burden quantification outperforms these readouts in reliability, sensitivity, and time to the detection of treatment effects in both triazole-susceptible and -resistant infections and can thus lead to better translatability from in vitro antifungal screening results to in vivo confirmation in mouse and human studies.

Complete Genome Sequence of Stenotrophomonas maltophilia Podophage Pepon.

ABSTRACTStenotrophomonas maltophilia is an opportunistic bacterium that is commonly associated with respiratory infections in immunocompromised patients, including cystic fibrosis patients. In this report, we introduce the complete genome sequence of S. maltophilia podophage Pepon, which is a T7-like phage closely related to the previously reported phage Ponderosa.

The Role of Flexible Bronchoscopy in Swab-negative Patients During the SARS-CoV2 Pandemic.

The Role of Flexible Bronchoscopy in Swab-negative Patients During the SARS-CoV2 Pandemic.

Diagnosis of severe respiratory infections in immunocompromised patients.

An increasing number of critically ill patients are immunocompromised. Acute hypoxemic respiratory failure (ARF), chiefly due to pulmonary infection, is the leading reason for ICU admission. Identifying the cause of ARF increases the chances of survival, but may be extremely challenging, as the underlying disease, treatments, and infection combine to create complex clinical pictures. In addition, there may be more than one infectious agent, and the pulmonary manifestations may be related to both infectious and non-infectious insults. Clinically or microbiologically documented bacterial pneumonia accounts for one-third of cases of ARF in immunocompromised patients. Early antibiotic therapy is recommended but decreases the chances of identifying the causative organism(s) to about 50%. Viruses are the second most common cause of severe respiratory infections. Positive tests for a virus in respiratory samples do not necessarily indicate a role for the virus in the current acute illness. Invasive fungal infections (Aspergillus, Mucorales, and Pneumocystis jirovecii) account for about 15% of severe respiratory infections, whereas parasites rarely cause severe acute infections in immunocompromised patients. This review focuses on the diagnosis of severe respiratory infections in immunocompromised patients. Special attention is given to newly validated diagnostic tests designed to be used on non-invasive samples or bronchoalveolar lavage fluid and capable of increasing the likelihood of an early etiological diagnosis.Electronic supplementary materialThe online version of this article (10.1007/s00134-019-05906-5) contains supplementary material, which is available to authorized users.

Human parainfluenza virus-3 can be targeted by rapidly ex vivo expanded T lymphocytes

Background aimsHuman parainfluenza virus-3 (HPIV) is a common cause of respiratory infection in immunocompromised patients and currently has no effective therapies. Virus-specific T-cell therapy has been successful for the treatment or prevention of viral infections in immunocompromised patients but requires determination of T-cell antigens on targeted viruses. MethodsHPIV3-specific T cells were expanded from peripheral blood of healthy donors using a rapid generation protocol targeting four HPIV3 proteins. Immunophenotyping was performed by flow cytometry. Viral specificity was determined by interferon (IFN)-γ ELISpot, intracellular cytokine staining and cytokine measurements from culture supernatants by Luminex assay. Cytotoxic activity was tested by 51Cr release and CD107a mobilization assays. Virus-specific T cells targeting six viruses were then produced by rapid protocol, and the phenotype of HPIV3-specific T cells was determined by immunomagnetic sorting for IFN-γ-producing cells. ResultsHPIV3-specific T cells were expanded from 13 healthy donors. HPIV3-specific T cells showed a CD4+ predominance (mean CD4:CD8 ratio 2.89) and demonstrated specificity for multiple HPIV3 antigens. The expanded T cells were polyfunctional based on cytokine production but only had a minor cytotoxic component. T cells targeting six viruses in a single product similarly showed HPIV3 specificity, with a predominant effector memory phenotype (CD3+/CD45RA–/CCR7–) in responder cells. DiscussionHPIV3-specific T cells can be produced using a rapid ex vivo protocol from healthy donors and are predominantly CD4+ T cells with Th1 activity. HPIV3 epitopes can also be successfully targeted alongside multiple other viral epitopes in production of six-virus T cells, without loss of HPIV3 specificity. These products may be clinically beneficial to combat HPIV3 infections by adoptive T-cell therapy in immune-compromised patients.

Herpesvirus Respiratory Infections in Immunocompromised Patients: Epidemiology, Management, and Outcomes.

Among immunocompromised individuals, members of the human Herpesviridae family are frequently encountered pathogens. Cytomegalovirus, herpes simplex virus 1 and 2, varicella zoster virus, Epstein–Barr virus, and human herpesvirus-6, -7, and -8 all establish latency after infection and can reactivate during periods of immunosuppression, leading to both direct and indirect adverse effects on the host including severe organ dysfunction as well as allograft rejection and loss after transplantation. While not all herpesviruses are primary respiratory pathogens, many of their manifestations include involvement of the respiratory tract. This article discusses the individual viruses, their epidemiology, and clinical manifestations as well as recommended treatment and preventive strategies.

Clinical significance, antimicrobial susceptibility and molecular identification of Nocardia species isolated from children with cystic fibrosis.

Nocardia is an opportunistic pathogen that causes respiratory infections in immunocompromised patients. The aim of this study was to analyze the epidemiology, clinical significance and antimicrobial susceptibility of Nocardia species isolated from eight children with cystic fibrosis. The isolated species were identified as Nocardia farcinica, Nocardia transvalensis, Nocardia pneumoniae, Nocardia veterana and Nocardia wallacei. N. farcinica was isolated in three patients and all of them presented lung affectation with a chronic colonization and pneumonia. N. farcinica showed resistance against gentamicin, tobramycin, cefotaxime, but was susceptible to trimethoprim-sulfamethoxazole and amikacin. N. transvalensis, which was isolated from two patients, showed an association with chronic colonization. N. transvalensis was resistant to tobramycin and amikacin, but susceptible to ciprofloxacin, trimethoprim-sulfamethoxazole and cefotaxime. N. veterana, N. pneumoniae and N. wallacei were isolated from three different patients and appeared in transitory lung colonization. N. veterana and N. pneumoniae were susceptible to imipenem, trimethoprim-sulfamethoxazole, amikacin, tobramycin, and cefotaxime. N. wallacei was resistant to amikacin, tobramycin, imipenem, and trimethoprim-sulfamethoxazole and susceptible to ciprofloxacin and cefotaxime. All the isolates were identified up to species level by 16S rRNA gene sequencing. The presence of Nocardia in the sputum of patients with cystic fibrosis is not always an indication of an active infection; therefore, the need for a treatment should be evaluated on an individual basis. The detection of multidrug-resistant species needs molecular identification and susceptibility testing, and should be performed for all Nocardia infections.

Accurate identification of members of the Burkholderia cepacia complex in cystic fibrosis sputum.

The Burkholderia cepacia complex (BCC) is a group of closely related species which includes opportunistic pathogens causing chronic respiratory infections in immunocompromised patients, or individuals affected by cystic fibrosis (CF). Other Burkholderia species causing infection in the CF population are Burkholderia gladioli and Burkholderia pseudomallei. Traditional phenotypic analyses have been demonstrated to be inadequate for reliable identifications of isolates of BCC and B.gladioli. A pan-genomic analysis approach was used to design species-specific probes for Burkholderia cenocepacia, B.cepacia, Burkholderia multivorans, Burkholderia vietnamiensis, Burkholderia ambifaria, Burkholderia dolosa, Burkholderia pyrrocinia and B.gladioli. Multiplex real-time PCR assay was developed and tested using sputum specimens collected from CF patients spiked with Burkholderia species. The assay exhibited 100% sensitivity for all eight target species and detected 10(2) to 10(3) CFUml(-1) when applied to spiked sputum. Our PCR assay resulted highly specific for each of the Burkholderia species tested, allowing discrimination among Burkholderia and non-Burkholderia pathogens. Analysis carried out on 200 sputa positive for the presence of Burkholderia revealed that PCR assay and recA sequencing were fully comparable for identification of Burkholderia at the level of species. Burkholderia cepacia complex (BCC) has a complex taxonomic organization and its identification is a challenge for microbiology laboratories. Nonidentification or misidentification of BCC isolates represent a problem in epidemiology and treatment of cystic fibrosis patients. The high specificity and sensitivity of the multiplex Real-time PCR assay developed in this study indicates its potential to be a rapid and reliable method for the detection of Burkholderia at the level of species from sputum samples of cystic fibrosis patients.

Pseudofungal tap water contaminants in sputum cytology

Detection of contaminants in cytological smears, both intrinsic and extrinsic in origin, is an important aspect to take into account in the routine work that is carried out in Cytopathology laboratories. In many of them, tap water is commonly utilized in some steps of the Papanicolaou staining method such as hydration, rinse, and blueing. Because of its source in lakes and reservoirs, and under certain climatic circumstances (high temperatures and low rainfall), fresh water may suffer a phenomenon termed ‘‘Eutrophication’’ where, due to an overproduction of nutrients, an excessive growth of different microorganisms occurs. So, running tap water may be affected by a biological contamination and, occasionally, some types of microorganisms such as bacteria, algae, protozoa, worms, and arthropods may appear as contaminants in the cytological smears. Herein, different examples of contamination by four species of algae that were observed in sputum smears stained by the Papanicolaou method are shown. Due to their filamentous appearance, initially they were misinterpreted as uncommon fungal structures. Figure C-1A shows an elongated structure, in the shape of a chain, and consisting of 11 cylindrical/rectangular drum-like cells (10–40 3 5–20 lm in size). Each cell is joined to the next by its valvar surface. The dark tonality of the surface of some cells is due to siliceous material deposited thereon. These cells are held in a filament by means of a thin mucilaginous envelope. In this case, Melosira sp. (class Diatomeae) was the most-likely species to consider. These algae are very common in freshwater habitats, especially eutrophic waters. Because of their morphological features, this structure could be misinterpreted as arthrospores of Geotricum sp., a fungus that may cause respiratory infections in immunocompromised patients. However, arthrospores are much more rectangular in shape and less wide than alga cells, with rounded ends, variable sizes (6–12 3 3–6 lm), not always oriented in the same direction and they can appear scattered. Moreover, Geotricum produces hyaline septate hyphae which show dichotomous branching. In Figure C-1B, on a background with mucus, leukocytes, and some macrophages, there appears a very long unbranched filament (15–25lm in wide), bluish in color, with a thin cellular wall and dentated surface, formed by identical clear cells, rectangular or square in shape, and containing a round chloroplast. On the basis of these morphological features, this structure was tentatively identified as a filamentous green algae belonging to Ulothrix sp. This species is frequently found in cold oxygen-rich fresh waters, mainly in spring and summer. Absence of branching, spores, and budding phenomena are important points in order to reject the presence of fungal elements such as the conidiophore of diverse types of fungi. Figure C-1C shows a filamentous structure where the cells are connected end-to-end forming something similar to a chain. Vegetative cells (Antheridium) appear as short cylinders in shape (15–20 lm wide), and the bulb-like structures (Oogonium) located between the vegetative cells are egg cells. This structure was tentatively identified as a green algae belonging to Oedogonium sp. This species is widely distributed in all kinds of fresh water. In this case, Blastomyces dermatitidis, a fungus that can also cause pulmonary infections, should be taken into account for its differential diagnosis. The microscopic appearance of this dimorphic fungus may be like hyaline CFGS Anatomia Patologica y Citologia, Instituto de Piedras Blancas, Asturias, Spain *Correspondence to: Rafael Martinez-Giron, Ph.D., M.D., CFGS Anatomia Patologica y Citologia, Instituto de Piedras Blancas, Avda. Principal, 33. 33450-P, Plancas-Asturias, Spain. E-mail: rmartinezgiron@hotmail.com Received 7 March 2012; Revision 26 July 2012; Accepted 25 September 2012 DOI 10.1002/dc.22937 Published online 16 November 2012 in Wiley Online Library (wileyonlinelibrary.com).

Profiling of Burkholderia cepacia Secretome at Mid-Logarithmic and Early-Stationary Phases of Growth

Background Burkholderia cepacia is a Gram-negative pathogen that causes serious respiratory infections in immunocompromised patients and individuals with cystic fibrosis. This bacterium is known to release extracellular proteins that may be involved in virulence.Methodology/Principal FindingsIn the present study, B. cepacia grown to mid-logarithmic and early-stationary phases were investigated on their ability to invade and survive intracellularly in A549 lung epithelial cells in order to discern the fate of these bacteria in the pathogenesis of B. cepacia lung infections in in vitro condition. The early-stationary phase B. cepacia was demonstrated to be more invasive than mid-logarithmic phase. In addition, culture supernatants of B. cepacia obtained from these phases of growth were also demonstrated to cause different cytotoxic potency on the A549 human lung epithelial cells. Profiling of the supernatants using the gel-based proteomics approach identified 43 proteins that were commonly released in both the growth phases and 40 proteins newly-released at the early-stationary phase. The latter proteins may account for the higher cytotoxic activity of the early-stationary culture supernatant compared to that obtained at the mid-logarithmic phase. Among the newly-released proteins in the early-stationary phase supernatant were flagellar hook-associated domain protein (FliD), flagellar hook-associated protein (FlgK), TonB-dependent siderophore (Fiu), Elongation factor G (FusA), phosphoglycerate kinase (Pgk) and sulfatase (AslA) which are known for their virulence.Conclusion/SignificanceDifferences in the ability of B. cepacia to invade and survive intracellularly inside the epithelial cells at different phases of growth may improve our understanding of the varied disease progressions associated with B. cepacia infections. In addition, the identified culture supernatant proteins may be used as targets for the development of new strategies to control B. cepacia infection using agents that can block their release.

CD209/DC-SIGN mediates efficient infection of monocyte-derived dendritic cells by clinical adenovirus 2C isolates in the presence of bovine lactoferrin

Adenovirus often causes respiratory infection in immunocompromised patients, but relevant attachment receptors have largely not been defined. We show that the antiviral protein bovine lactoferrin enhances infection of monocyte-derived dendritic cells (MDDC) by adenovirus species C serotype 2 (2C) isolates. Under the same conditions infection of MDDC by human( )cytomegalovirus was reduced. Adenoviral infection was prominently enhanced by bovine but not human lactoferrin, and was not prominently enhanced using blood monocyte-derived macrophages, suggesting that the relevant receptor is expressed on MDDC. Infection of MDDC in the presence of bovine lactoferrin was blocked by mannan, and an antibody to CD209/DC-SIGN but not isotype control or CD46 antibodies. Lastly, U937 macrophages ectopically expressing CD209/DC-SIGN, but not parental U937 cells, were efficiently infected by adenovirus 2C in the presence of bovine lactoferrin. These results may provide a tool, given the high efficiency of infection, to dissect responses by myeloid cells to clinical adenovirus isolates.

Respiratory infections in immunocompromised patients

Immunosuppressive states and therapies are becoming common in clinical practice. Recent advances and trends in bacterial, fungal, viral and parasitic pulmonary infections in immunosuppressed patients are described. Pulmonary infections can jeopardize the prognosis of immunosuppressed patients. The number of patients infected with multidrug-resistant bacteria or opportunistic pathogens like rapid-growing environmental mycobacteria, Strongyloides stercoralis or Rhodococcus equi is increasing with the increased numbers of immunosuppressed patients due to HIV/AIDS and the potent immunosuppressive therapies used in solid-organ and haematopoietic transplantations, cancer and systemic illnesses. The slow development of more effective antibiotics underlines the necessity of preventive measures, development of rapid detection tests for pathogens and appropriate treatment regimens to avoid development of further resistance. Adequate prophylaxis, clinical suspicion, microbiological and molecular investigations, drug susceptibility-based antibiotic treatment and new drug development are strategies required to face up to the challenge of pulmonary infections in immunodepressed patients.

Use of Multicopy and Single Copy Genes for Detection of Pneumocystis jirovecii and Subsequent Analysis of Genotypes of Indian Isolates

Background: Pneumocystis carinii Pneumonia (PCP) caused by an opportunistic agent Pneumocystis jirovecii is one of the most serious respiratory infections in immunocompromised patients including HIV infected individuals. Enormous gaps still exist in understanding the basic biology of the organism and epidemiology of PCP due to nonavailability of an appropriate propagation system. In the present study, we carried out molecular detection of the organism using two multicopy and one single copy gene. Further genotypic study was performed on some of the isolates to assess the genotypes. Methods: From November 2005 to October 2006, 114 different respiratory specimens were collected from 90 patients with various underlying conditions and a clinical suspicion of PCP. PCR was done for three independent gene loci including two multicopy i.e. Major Surface Glycoprotein (MSG) and mitochondrial Large subunit rRNA (mtLSUrRNA) and one single copy, internal transcribed spacer (ITS) region Results: Single round MSG and mtLSUrRNA PCR showed 9 positive isolates. External round of ITS PCR detected 6 cases while only nested round could detect all 9 cases. On applying nested PCR for mtLSUrRNA and ITS PCR we detected 5 additional cases. We further sequenced six isolates for mtLSUrRNA gene. Different genotypes of Pneumocystis were distinguished by identifying polymorphisms at position 85 and 248 of mtLSUrRNA. Two genotypes i.e. type 2 (5/6) and 3, (1/6) were observed among the six isolates. Also, one of our previous isolate showed genotype 1. Conclusion: Thus, among multicopy genes, MSG and mtLSUrRNA appears to be equally sensitive while in case of single copy ITS a nested PCR assay is required. In our present study, genotype 2 was more frequently detected (5/7), followed by type 3 and 1(1/7) and a prospective study with large number of patients is being carried out in our centre to address this issue. To our knowledge this is the first study from South Asia describing genotypes of isolates of P. jirovecii .

Analysis of Internal Transcribed Spacer 1 Sequences of Pneumocystis jiroveci from Clinical Specimens

Pneumocystis jiroveci (formerly Pneumocystis carinii f. sp. hominis) is one of the causative agents of the most serious fungal respiratory infections in immuno-compromised patients. Although P. jiroveci infections have been increasing, there are few data on the P. jiroveci genotypes in Korea. This study was performed to investigate the genetic diversity of P. jiroveci detected from clinical specimens. Twenty-one P. jirovecipositive respiratory samples detected by polymerase chain reaction were collected from a tertiary-care hospital in Seoul between Jan 2003 and Aug 2006. Internal Transcribed Spacer (ITS) sequence analysis was performed by direct sequencing. Only 9 specimens were appropriate for sequence analysis. Twelve specimens, however, showed mixed sequences by direct sequencing. Three ITS genotypes of P. jiroveci were found. There is limited genetic diversity of ITS genes of P. jiroveci from clinical isolates analyzed in this study. The present ITS gene analysis suggests that most of P. jiroveci isolates may have genetic similarity among patients in Korea.

Protective effects of green tea catechins on alveolar macrophages against bacterial infections

Bacterial pneumonia in immunocompromised patients as well as elderly persons often becomes a life threatening disease, even when effective antibiotics are used extensively. In addition, the appearance of antibiotic-resistant bacteria in medical facilities as well as in patients requires another approach to treat such patients besides treatment with antibiotics. In this regard, green tea catechins, such as epigallocatechin gallate (EGCg), may be one of the potential agents for such purpose due to its possible potential immunomodulatory as well as antimicrobial activity. The studies by us showed that EGCg enhanced the in vitro resistance of alveolar macrophages to Legionella pneumophila infection by selective immunomodulatory effects on cytokine formation. Furthermore, the tobacco smoking-induced impairment of alveolar macrophages regarding antibacterial as well as immune activity was also recovered by EGCg treatment. These results indicate that EGCg may be a possible potential immunotherapeutic agent against respiratory infections in immunocompromised patients, such as heavy smokers.

Respiratory infections in immunocompromised patients.

HIV disease has been dramatically reduced in the developed world by the introduction of highly active antiretroviral therapy, with implications that prophylactic therapy against opportunistic infections may be stopped; however, tuberculosis is an escalating problem in the HIV-infected and HIV-noninfected populations worldwide. Compliance with effective treatment regimens, especially through directly observed therapy, remains the cornerstone of tuberculosis control strategies. Although tuberculosis prophylaxis is of benefit for tuberculin skin reactors with HIV in the developed world, several reservations are voiced about this approach in resource-poor settings. Recent advances in technology, particularly in antigen-specific systems, have revolutionized the understanding of HIV immunology and helped to elucidate the mechanisms of pathogenesis in diseases such as cytomegalovirus. In bone marrow transplantation and solid-organ transplantation patients, quantitative polymerase chain reaction (PCR) to predict cytomegalovirus disease is an important advance, and patients who undergo bone marrow transplantation, CT scanning has proven useful in the diagnosis of pulmonary aspergillosis.

Epidemiology of Chlamydia pneumoniae

Chlamydia pneumoniae is the most commonly occurring intracellular bacterial pathogen. It is frequently involved in respiratory tract infections and to a lesser degree in extrapulmonary diseases. According to seroepidemiologic surveys, C. pneumoniae infection seems to be both endemic and epidemic. Such studies indicate that C. pneumoniae infection is widespread, with frequent reinfection during a lifetime. In Western countries the highest rate of new infections occurs between the ages of 5 and 15. The antibody prevalence worldwide is higher in adult males than in females. Currently available data suggest that C. pneumoniae is primarily transmitted from human to human without any animal reservoir. Transmission seems to be inefficient, although household outbreaks with high transmission rates are reported. Most reports rank C. pneumoniae among the three most common etiologic agents of community-acquired pneumonia, with an incidence ranging from 6% to 25%, and generally presenting a mild and, in some cases, self-limiting clinical course. Recent reports also indicate a possible role for C. pneumoniae in severe forms of community-acquired pneumonia and in respiratory infections in immunocompromised patients. C. pneumoniae infection has also been implicated in the pathogenesis of asthma in both adults and children. The hypothesis that C. pneumoniae infection could lead to asthma is based on clinical studies and on the evidence of specific IgE production, direct epithelial damage, induction of T-cell immunopathologic diseases, and vascular smooth cell infection. Chronic C. pneumoniae infection seems to be common in patients with chronic bronchitis whether exacerbated or not, and is characterized by a strong humoral immune response to this intracellular microorganism, which is present in the majority of patients with severe chronic bronchitis. More than 60% of subjects with chronic bronchitis have specific C. pneumoniae antibody titers, and the microorganism may be identified by culture or PCR in almost 40% of these patients. This pathogen has also been recently associated with atherosclerosis and coronary heart disease (CHD). Seroepidemiological evidence indicates that the majority of patients with CHD present an anti-C. pneumoniae antibody pattern consistent with chronic infection. Furthermore, C. pneumoniae has been detected in atherosclerotic coronary plaques by several methods, including immunocytochemistry, transmission electron microscopy and molecular biology techniques. Recently, we detected C. pneumoniae DNA in a high percentage (51%) of aortic aneurysm plaques. Moreover, our serologic data support the hypothesis that a chronic C. pneumoniae antibody pattern may be a possible risk marker for atherosclerosis. Recently, C. pneumoniae has been isolated by culture from the coronary artery of a patient with coronary atherosclerosis, providing direct evidence of the presence of viable organisms in atheromatous lesions. Moreover, we recently demonstrated an association between C. pneumoniae reinfection and acute myocardial infarction.

Diagnostic Value of Protected BAL in Diagnosing Pulmonary Infections in Immunocompromised Patients

To assess the diagnostic utility of protected BAL (P-BAL) in respiratory infections in immunocompromised patients and to examine whether P-BAL alone could substitute the combined use of protected specimen brush (PSB) and BAL in such patients. Thirty-seven immunocompromised patients who underwent PSB, P-BAL, and BAL simultaneously for the diagnosis or exclusion of bacterial or nonbacterial opportunistic respiratory infections were studied prospectively. The P-BAL was performed through the inner catheter of a telescoping plugged catheter with 60 mL of saline solution. Thirteen (35%) cases of bacterial pneumonia were diagnosed. PSB obtained seven true-positive (TP) results, P-BAL obtained nine, and BAL obtained eight TP. Results of the three techniques were positive and concordant in 6 of the 13 cases. PSB remained free of contamination from oropharyngeal flora in all cases, P-BAL was contaminated twice, and BAL was contaminated in four cases. Opportunistic respiratory infections were diagnosed in 19 patients. P-BAL results were identical to those with BAL in all cases: 18 TP and 1 false-negative. The average volume of P-BAL fluid retrieved was 19 mL, sufficient for all microbiologic and cytologic processings. P-BAL was more time-consuming than both PSB and BAL procedures and was technically more complex. P-BAL alone can substitute the combined use of both PSB and BAL in immunocompromised patients and attains a higher sensitivity than PSB in diagnosing bacterial pneumonia. The combined strategy continues to be a good choice, but due to the high incidence of bacterial pneumonia in these patients, a highly efficient diagnostic procedure is required not only for nonbacterial opportunistic respiratory infections but also for bacterial pneumonia.