1/7. Cavitary pneumonia in an AIDS patient caused by an unusual bordetella bronchiseptica variant producing reduced amounts of pertactin and other major antigens.Although bordetella bronchiseptica can infect and colonize immunocompromised humans, its role as a primary pathogen in pneumonia and other respiratory processes affecting those patients remains controversial. A case of cavitary pneumonia caused by B. bronchiseptica in an AIDS patient is presented, and the basis of the seemingly enhanced pathogenic potential of this isolate (designated 814) is investigated. B. bronchiseptica was the only microorganism recovered from sputum, bronchoalveolar lavage fluid, and samples taken through the protected brush catheter. Unlike previous work reporting the involvement of B. bronchiseptica in cases of pneumonia, antibiotic treatment selected on the basis of in vitro antibacterial activity resulted in clearance of the infection and resolution of the pulmonary infiltrate. Although isolate 814 produced reduced amounts of several major antigens including at least one Bvg-activated factor (pertactin), the molecular basis of this deficiency was found to be BvgAS independent since the defect persisted after the bvgAS locus of isolate 814 was replaced with a wild-type bvgAS allele. Despite its prominent phenotype, isolate 814 displayed only a modest yet a significant deficiency in its ability to colonize the respiratory tracts of immunocompetent rats at an early time point. Interestingly, the antibody response elicited by isolate 814 in these animals was almost undetectable. We propose that isolate 814 may be more virulent in immunocompromised patients due, at least in part, to its innate ability to produce low amounts of immunogenic factors which may be required at only normal levels for the interaction of this pathogen with its immunocompetent natural hosts.- - - - - - - - - - ranking = 1keywords = antigen (Clic here for more details about this article) |
2/7. Severe chlamydophila psittaci pneumonia rapidly diagnosed by detection of antigen in sputum with an immunochromatography assay.We report a case of severe Chlamydophila (chlamydia) psittaci pneumonia rapidly diagnosed by detection of antigen in sputum with an immunochromatography assay. The patient was admitted to our hospital because of shock, disturbance of consciousness, accidental hypothermia, and multiple organ dysfunction syndrome, and he recovered after administration of intravenous erythromycin and high-dose methylpredonisolone therapy. psittacosis was confirmed by detection of 16S rRNA gene of C. psittasi in sputum with multiplex-polymerase chain reaction analysis. Serological responses to C. psittasi, C. trachomatis, and C. pneumoniae were also evaluated, and serological cross-reactivity was observed between each species. We consider that the commercially available immunochromatography assay for chlamydia species can be helpful for rapid diagnosis of chlamydia infection of the respiratory tract. Hereafter, further examination will be necessary regarding pretreatment of specimens or detection sensitivity and specificity.- - - - - - - - - - ranking = 1keywords = antigen (Clic here for more details about this article) |
3/7. Report of cases of and taxonomic considerations for large-colony-forming Lancefield group C streptococcal bacteremia.Traditionally, group C streptococci include four species: streptococcus equisimilis, S. zooepidemicus, S. equi, and S. dysgalactiae, the first three of which are group C beta-hemolytic streptococci (GCBHS). However, many of the beta-hemolytic streptococci carrying Lancefield group C antigen isolated from clinical specimens are S. milleri. These organisms can be differentiated by colony size. We retrospectively collected data concerning large-colony-forming GCBHS bacteremia that occurred during a period of 8 years at the massachusetts General Hospital. A total of 222 cases of beta-hemolytic streptococcal bacteremia were identified; data on the Lancefield grouping were available in 192 cases: 45 cases (23.6%) were group A, 96 cases (50%) were group B, 7 cases (3.6%) were group C (large colony forming), and 44 cases (22.9%) were group G. The medical records for cases of large-colony-forming GCBHS bacteremia were reviewed. In one case, the isolate was thought to be a contaminant; the other six cases are reported (five males and one female; mean age, 55 years). All patients had severe underlying conditions, and none had a history of exposure to animals. The clinical syndromes included two cases of cellulitis and one case each of endocarditis, myocardial infarction complicated by infection, pneumonia, and myofasciitis. The diagnoses for two patients with endovascular infections were delayed. Three of the six patients had fatal outcomes, and other two, after prolonged hospitalization, were transferred to a long-term rehabilitation center. We concluded that the severe outcomes reflect delay in diagnosis and treatment as well as the severity of the underlying diseases. The taxonomy of GCBHS is discussed. More reports differentiating large- and small-colony-forming GCBHS are needed.- - - - - - - - - - ranking = 0.2keywords = antigen (Clic here for more details about this article) |
4/7. Characterization of two unusual clinically significant Francisella strains.We have isolated two phenotypically distinct nonfastidious Francisella strains (Fx1 and Fx2) from the blood of compromised patients with pneumonia and compared them with eight other Francisella strains, including francisella tularensis biovar tularensis, F. tularensis biovar novicida, and F. philomiragia. Our isolates grew well on sheep blood agar, chocolate agar, modified Thayer-Martin agar, and Trypticase soy agar. Fx1 and Fx2 were determined to be within the Francisella genus by cellular fatty acid analysis and by the utilization of glucose, production of H2S and catalase, and lack of motility, oxidase, nitrate reductase, and gelatinase. They were additionally shown to belong to the species F. tularensis by sequencing of two variable regions comprising approximately 500 nucleotides of the 16S rRNA gene. Also, rna probe hybridization confirmed their belonging to the species F. tularensis. However, the new strains, which are not identical, are distinguished from other F. tularensis strains by growth characteristics, repetitive extragenic palindromic PCR fragment pattern, and some biochemical tests. Key biochemical differences included the findings that Fx1 was positive for beta-galactosidase and arabinose hydrolysis and that both strains were citrulline ureidase positive and glycerol negative. Commercial F. tularensis antiserum agglutinated stock F. tularensis strains but not Fx1, Fx2, F. tularensis biovar novicida, or F. philomiragia; serum from either patient failed to agglutinate or only weakly agglutinated commercial antigen but showed agglutination when tested against each patient's respective isolate. Fx1 and Fx2 produced beta-lactamase. Because of their good growth, negative serology, and biochemical profile, the organisms could be misidentified in the clinical laboratory if standard strategies or commercial identification systems are used.- - - - - - - - - - ranking = 0.2keywords = antigen (Clic here for more details about this article) |
5/7. lung abcess complicating legionella micdadei pneumonia in an adult liver transplant recipient: case report and review.legionella micdadei (Pittsburgh pneumonia agent) is the second most common cause of legionella pneumonia, and occurs predominantly in immunocompromised hosts. L micdadei is the cause of nosocomial pneumonia in renal transplant recipients, but has not been described in other adult solid organ transplant recipients. This report describes the first case of L micdadei pneumonia in an adult liver transplant recipient on immunosuppressive therapy. Importantly, this case highlights the difficulties in establishing the diagnosis, as the legionella urinary antigen is negative, and special culture conditions are required. Furthermore, this case illustrates several atypical clinical features of L micdadei pneumonia in a transplant recipient, including a community acquired mode of transmission, occurrence several years after organ transplantation, and lung abcess formation. The patient was successfully treated with limited surgical resection and quinolone antimicrobial monotherapy.- - - - - - - - - - ranking = 0.2keywords = antigen (Clic here for more details about this article) |
6/7. Cryptococcal pneumonia complicating pregnancy.In the present report we describe 4 previously healthy women who developed cryptococcal pneumonia during pregnancy, and 1 pregnant woman with cryptococcal meningitis. These cases illustrate a previously uncharacterized spectrum of cryptococcal disease. We also discuss 24 patients previously reported who had cryptococcal meningitis during pregnancy. Finally, we review the available data for each therapeutic option and present an algorithm for management based on appraisals of disease severity and risk to the unborn fetus. This report emphasizes the need for heightened awareness of cryptococcosis in the differential diagnosis of pneumonia, chest pain, and hypoxemia in the pregnant patient, but at present, there are insufficient epidemiologic data to determine whether incidences of pulmonary or disseminated cryptococcosis actually increase during pregnancy. The risk of congenital cryptococcosis to the unborn fetus is low, and the most likely mechanism whereby neonates acquire invasive fungal pulmonary infection is through aspiration. While it is unclear whether there is any real increased risk of spontaneous abortion or premature labor, the data indicate that overall fetal outcome depends on effective treatment of maternal infection. For patients with dense air-space consolidation, progressive pulmonary disease, or dissemination, antifungal therapy is necessary. Optimal treatment is determined by the acuity and severity of the clinical presentation. Amphotericin B (approximately 1 g) with or without flucytosine represents the choice for initial treatment of the more acutely ill patient with disseminated or progressive pulmonary cryptococcosis who requires hospitalization (whether during or after pregnancy). Oral fluconazole appears to be safe and effective alternative therapy after delivery for the less severely ill patient who can be managed on an outpatient basis. While the use of fluconazole during pregnancy generally appears safe in terms of fetal outcome (49, 58), the class C status and single report of fetal malformation (62) preclude confident recommendation for its use during pregnancy. The risks and benefits of this effective and generally less toxic drug should be discussed with the parents and weighed against the use of amphotericin b. For pregnant women with limited pulmonary cryptococcosis (segmental or nodular infiltrates) and no evidence of dissemination, we recommend close follow-up without antifungal therapy similar to the recommendation for normal hosts with minimal disease. However, it is important to note that there is no extensive experience upon which to base this recommendation for pregnant individuals (45, 55, 103, 108). It is prudent to use frequent physical examinations (for example, every 1-2 months), combined with chest roentgenograms and serum cryptococcal antigens to monitor progression and/or development of disease in both the mother and child for approximately 6 months postpartum. In conclusion, cryptococcosis during pregnancy presents a special challenge to the clinician. A balanced therapeutic approach holds great promise for successful maternal and fetal outcomes.- - - - - - - - - - ranking = 0.2keywords = antigen (Clic here for more details about this article) |
7/7. Value of noninvasive studies in community-acquired pneumonia.Noninvasive diagnostic studies, i.e., sputum gram stain, sputum culture, blood culture and antigen detection assays will assist the clinician in the selection of initial antimicrobial therapy in some patients. These tests may be even more valuable in adjusting treatment regimens to prevent the use of broad spectrum antimicrobial agents as routine therapy.- - - - - - - - - - ranking = 0.2keywords = antigen (Clic here for more details about this article) |