The incidence of Chlamydia pneumoniae lower respiratory tract infections among university students in northern California.

Chlamydia pneumoniae has recently been identified as a cause of lower respiratory tract infections. From March 1987 to March 1988, 259 university students-151 students with lower respiratory tract infections and 108 controls-from the University of California, Berkeley, were studied to determine the incidence and pattern of C pneumoniae lower respiratory tract infections. Serologic evidence of a recent C pneumoniae infection was found in less than 2%, and the organism was not isolated from any of the subjects. Despite the paucity of evidence of a recent infection, 47.5% of this university population showed serologic evidence of a previous C pneumoniae infection. The lower incidence of C pneumoniae infection in our population, when compared with previous reports, suggests that there may be geographic and temporal differences or fluctuations among populations.     

Vaccination against infections by Chlamydia pneumoniae

Chlamydia pneumoniae is an intracellularly growing bacterium that causes respiratory infections and is strongly associated with atherosclerosis. Antibodies against C. pneumoniae are frequently encountered in the adult population, indicating past exposure to the micro-organism. Immunity to reinfection is, however, only partial and does not prevent development of sequelae. Infections caused by and associated with C. pneumoniae are a major cause of morbidity and mortality world wide. Development of a vaccine capable of protecting against infections due to C. pneumoniae and their sequelae would prevent up to 10% of community-acquired pneumonias in adults and add a new dimension to the prevention of atherosclerosis and coronary heart disease.     

Acute respiratory disease in the United States Army in the Republic of Vietnam, 1965-1970.

Respiratory tract infections represented one of the commonest illnesses that occurred among U.S. Army personnel stationed in the Republic of Vietnam. Between 1965 and 1970 the years of this review, respiratory tract infections ranked approximately equal to diarrheal disease as a cause of hospitalization or assignment to quarters. Rates varied between 20 and 110 per 1000 troops per year. The specific casual agents responsible for acute respiratory diseases in Vietnam were not defined. Limited observations suggest that members of the adenovirus group and respiratory syncytial viruses were involved. During the fall of 1968, influenza due to the A2 Hong Kong strain (H3N2) was widespread, but it was not associated with marked increases in rates of hospitalization or mortality. Mycoplasma pneumoniae was the most common demonstrable causative agent in soldiers admitted to hospitals with pneumonia, 42% in one series.     

Use of the indirect immunofluorescence test in the diagnosis of an infection, caused by Mycoplasma pneumoniae

The indirect immunofluorescence test has been used for the serodiagnosis of M. pneumoniae infections in two paired blood sera of patients with acute respiratory diseases and acute pneumonia. The optimum methods for obtaining M. pneumonia antigen, its fixation and storage have been determined. The data on the study of the sensitivity, specificity and diagnostic value of the test are presented. The indirect immunofluorescence test has been shown to be capable of the simultaneous detection of complete (complement-binding) and incomplete (not binding the complement) antibodies to M. pneumoniae. This test may be used in the diagnostic practice as a highly sensitive, specific and sufficiently simple serological method.     

肺炎支原体实验室检测方法研究进展

肺炎支原体(Mycoplosma pneumonia,MP)为人类非典型肺炎的病原体,是引起呼吸道感染的重要病原体。但是支原体肺炎与其他病原体感染的肺炎,在临床症状、影像学上并无特异性差别,且其对一般治疗肺炎、上呼吸道感染的药物有耐药性,因此肺炎支原体及时、准确的实验室检测对于支原体肺炎的诊断治疗显得尤为重要。目前MP的实验室检测方法不断推陈出新,但各种方法均有其优势与不足,临床可选择两种不同的方法同时检测。比如:血清学抗体的检测结合MP快速培养药敏的方法;血清学抗体的检测结合PCR的方法,不同方法相互补充为临床的早期诊断、治疗提供依据。而MP药敏试验的检测和耐药机制的研究对于临床用药方案的选择,减少耐药株的产生和流行具有重要意义。     

Identification of Klebsiella pneumoniae virulence determinants using an intranasal infection model

Klebsiella pneumoniae is a Gram-negative enterobacterium that has historically been, and currently remains, a significant cause of human disease. It is a frequent cause of urinary tract infections and pneumonia, and subsequent systemic infections can have mortality rates as high as 60%. Despite its clinical significance, few virulence factors of K. pneumoniae have been identified or characterized. In this study we present a mouse model of acute K. pneumoniae respiratory infection using an intranasal inoculation method, and examine the progression of both pulmonary and systemic disease. Wild-type infection recapitulates many aspects of clinical disease, including significant bacterial growth in both the trachea and lungs, an inflammatory immune response characterized by dramatic neutrophil influx, and a steady progression to systemic disease with ensuing mortality. These observations are contrasted with an infection by an isogenic capsule-deficient strain that shows an inability to cause disease in either pulmonary or systemic tissues. The consistency and clinical accuracy of the intranasal mouse model proved to be a useful tool as we conducted a genetic screen to identify novel virulence factors of K. pneumoniae. A total of 4800 independent insertional mutants were evaluated using a signature-tagged mutagenesis protocol. A total of 106 independent mutants failed to be recovered from either the lungs or spleens of infected mice. Small scale independent infections proved to be helpful as a secondary screening method, as opposed to the more traditional competitive index assay. Those mutants showing verified attenuation contained insertions in loci with a variety of putative functions, including a large number of hypothetical open reading frames. Subsequent experiments support the premise that the central mechanism of K. pneumoniae pathogenesis is the production of a polysaccharide-rich cell surface that provides protection from the inflammatory response.     

M. pneumoniae respiratory diseases: clinical features--children

Chest X-ray findings were studied in 618 pediatric patients with M. pneumoniae respiratory infections. Of these, 472 (76 percent) had pneumonia. Pneumonia was most frequently observed in the lower lung field and least frequently in the upper lung field. The enlargement of hilar lymph nodes was observed in 34 percent of patients with M. pneumoniae pneumonia in contrast to 5 to 9 percent of patients with pneumonia due to other agents, suggesting that it was rather characteristic of M. pneumoniae pneumonia. It was observed in no patients below one year of age, in 41 percent of those aged one to five years, and then decreased with increase in age. Of children with M. pneumoniae respiratory infections, fever, pneumonia, and positive CF test were less frequently observed in infants below one year, showing that they have slighter symptoms; positive IHA test was less frequently observed and isolation of M. pneumoniae was more frequently observed, as compared to other age groups, among whom these findings were similar. It must be kept in mind, however, that fatal cases of M. pneumoniae pneumonia in infants were reported.     

Chlamydia pneumoniae and atherosclerosis

Exposure to Chlamydia pneumoniae is extremely common, and respiratory infections occur repeatedly among most people. Strong associations exist between C. pneumoniae infection and atherosclerosis as demonstrated by: (i) sero-epidemiological studies showing that patients with cardiovascular disease have higher titres of anti-C. pneumoniae antibodies compared with control patients; (ii) detection of the organism within atherosclerotic lesions, but not in adjacent normal tissue by immunohistochemistry, polymerase chain reaction and electron microscopy and by culturing the organism from lesions; and (iii) showing that C. pneumoniae can either initiate lesion development or cause exacerbation of lesions in rabbit and mouse animal models respectively. The association of this organism with atherosclerosis has also provided sufficient impetus to conduct a variety of human secondary prevention antibiotic treatment trials. The results of these studies have been mixed and, thus far, no clear long-lasting benefit has emerged from these types of investigations. Studies of C. pneumoniae pathogenesis have shown that the organism can infect many cell types associated with both respiratory and cardiovascular sites, including lung epithelium and resident alveolar macrophages, circulating monocytes, arterial smooth muscle cells and vascular endothelium. Infected cells have been shown to exhibit characteristics associated with the development of cardiovascular disease (e.g. secretion of proinflammatory cytokines and procoagulants by infected endothelial cells and foam cell formation by infected macrophages). More detailed analysis of C. pneumoniae pathogenesis has been aided by the availability of genomic sequence information. Genomic and proteomic analyses of C. pneumoniae infections in relevant cell types will help to define the pathogenic potential of the organism in both respiratory and cardiovascular disease.     

The impact of the ancillary pilus-1 protein RrgA of Streptococcus pneumoniae on colonization and disease

The Gram-positive bacterium Streptococcus pneumoniae, the pneumococcus, is an important commensal resident of the human nasopharynx. Carriage is usually asymptomatic, however, S. pneumoniae can become invasive and spread from the upper respiratory tract to the lungs causing pneumonia, and to other organs to cause severe diseases such as bacteremia and meningitis. Several pneumococcal proteins important for its disease-causing capability have been described and many are expressed on the bacterial surface. The surface located pneumococcal type-1 pilus has been associated with virulence and the inflammatory response, and it is present in 20%–30% of clinical isolates. Its tip protein RrgA has been shown to be a major adhesin to human cells and to promote invasion through the blood-brain barrier. In this review we discuss recent findings of the impact of RrgA on bacterial colonization of the upper respiratory tract and on pneumococcal virulence, and use epidemiological data and genome-mining to suggest trade-off mechanisms potentially explaining the rather low prevalence of pilus-1 expressing pneumococci in humans.     

Acute viral infections of upper respiratory tract in elderly people living in the community: comparative,prospective, population based study of disease burden.

OBJECTIVE: To evaluate the disease burden of upper respiratory infections in elderly people living at home. DESIGN: Prospective surveillance of elderly people. INTERVENTION: None. SETTING: Leicestershire, England SUBJECTS: 533 subjects 60 to 90 years of age. MAIN OUTCOME MEASURES: Pathogens, symptoms, restriction of activity, duration of illness, medical consultations, interval between onset of illness and medical consultation, antibiotic use, admission to hospital, and death. RESULTS: 231 pathogens were identified for 211 (43%) of 497 episodes for which diagnostic specimens were available: 121 (52%) were rhinoviruses, 59 (26%) were coronaviruses, 22 (9.5%) were influenza A or B, 17 (7%) were respiratory syncytial virus, 7 (3%) were parainfluenza viruses, and 3 (1%) were Chlamydia species; an adenovirus and Mycoplasma pneumoniae caused one infection each. Infections occurred at a rate of 1.2 episodes per person per annum (95% confidence interval 1.0 to 1.7; range 0-10) and were clinically indistinguishable. Lower respiratory tract symptoms complicated 65% of upper respiratory infections and increased the medical consultation rate 2.4-fold (chi 2 test P < 0.001). The median interval between onset of illness and medical consultation was 3 days for influenza and 5 days for other infections. Rhinoviruses caused the greatest disease burden overall followed by episodes of unknown aetiology, coronaviruses, influenza A and B, and respiratory syncytial virus. CONCLUSIONS: Respiratory viruses cause substantial morbidity in elderly people. Although respiratory syncytial virus and influenza cause considerable individual morbidity, the burden of disease from rhinovirus infections and infections of unknown aetiology seems greater overall. The interval between onset of illness and consultation together with diagnostic difficulties raises concern regarding the role of antiviral drugs in treating influenza.     

Molecular evidence to support the expansion of the hostrange of Chlamydophila pneumoniae to include reptiles as well as humans,horses, koalas and amphibians

The Chlamydiales are a family of unique intracellular pathogens that cause significant disease in humans, birds and a wide range of animal hosts. Of the currently recognized species, Chlamydophila (previously Chlamydia) pneumoniae, unlike the other chlamydial species, has been previously considered to be solely a pathogen of humans, causing significant respiratory disease and has also been strongly connected with cardiovascular disease. Here we report the finding that strains of C. pneumoniae are widespread in the environment, being detected by molecular methods in a range of reptiles (snakes, iguanas, chameleons) and amphibians (frogs, turtles). Of particular interest was the finding that genotyping of the chlamydial major outer membrane protein gene in these newly identified C. pneumoniae strains showed that many were genetically very similar, if not identical to the human respiratory strains. Whether these reptilian and amphibian strains of C. pneumoniae are still capable of infecting humans, or crossed the host barrier some time ago, remains to be determined but may provide further insights into the relationship of this common respiratory infection with its human host.     

Species-specific interaction of Streptococcus pneumoniae with human complement factor H

Streptococcus pneumoniae naturally colonizes the nasopharynx as a commensal organism and sometimes causes infections in remote tissue sites. This bacterium is highly capable of resisting host innate immunity during nasopharyngeal colonization and disseminating infections. The ability to recruit complement factor H (FH) by S. pneumoniae has been implicated as a bacterial immune evasion mechanism against complement-mediated bacterial clearance because FH is a complement alternative pathway inhibitor. S. pneumoniae recruits FH through a previously defined FH binding domain of choline-binding protein A (CbpA), a major surface protein of S. pneumoniae. In this study, we show that CbpA binds to human FH, but not to the FH proteins of mouse and other animal species tested to date. Accordingly, deleting the FH binding domain of CbpA in strain D39 did not result in obvious change in the levels of pneumococcal bacteremia or virulence in a bacteremia mouse model. Furthermore, this species-specific pneumococcal interaction with FH was shown to occur in multiple pneumococcal isolates from the blood and cerebrospinal fluid. Finally, our phagocytosis experiments with human and mouse phagocytes and complement systems provide additional evidence to support our hypothesis that CbpA acts as a bacterial determinant for pneumococcal resistance to complement-mediated host defense in humans.     

Identifying vaccine antigens and assessing delivery systems for the prevention of bacterial infections

Bacterial infections in the respiratory tract and middle ear continue to be a major cause of morbidity and mortality despite the availability of antibiotic therapies. To assist development of vaccines for preventing these infections, animal models have been established in rodents. These models have been used effectively to evaluate different vaccination strategies. Our studies have found that for respiratory tract infections caused by Streptococcus pneumoniae, nontypeable Haemophilus influenzae (NTHI) and Moraxella catarrhalis, a primary immunisation targeted to the gut-associated lymphoid tissue was extremely effective in enhancing bacterial clearance. For the gram-negative pathogens, NTHI and M. catarrhalis, this mucosal immunisation was significantly more effective than systemic immunisation, however, for S. pneumoniae systemic immunisation was as effective. A strategy using these models has effectively been used to determine the potential of antigens from each of the pathogens to protect against infection. Antigens that demonstrate significant vaccine potential have been used to investigate delivery systems. One of the major challenges that still exists is to find mechanisms that will effectively deliver protein antigens to mucosal surfaces. Several strategies have been investigated and resulted in varying degrees of success.     

Identification of upper respiratory tract pathogens using electrochemical detection on an oligonucleotide microarray

Bacterial and viral upper respiratory infections (URI) produce highly variable clinical symptoms that cannot be used to identify the etiologic agent. Proper treatment, however, depends on correct identification of the pathogen involved as antibiotics provide little or no benefit with viral infections. Here we describe a rapid and sensitive genotyping assay and microarray for URI identification using standard amplification and hybridization techniques, with electrochemical detection (ECD) on a semiconductor-based oligonucleotide microarray. The assay was developed to detect four bacterial pathogens (Bordetella pertussis, Streptococcus pyogenes, Chlamydia pneumoniae and Mycoplasma pneumoniae) and 9 viral pathogens (adenovirus 4, coronavirus OC43, 229E and HK, influenza A and B, parainfluenza types 1, 2, and 3 and respiratory syncytial virus. This new platform forms the basis for a fully automated diagnostics system that is very flexible and can be customized to suit different or additional pathogens. Multiple probes on a flexible platform allow one to test probes empirically and then select highly reactive probes for further iterative evaluation. Because ECD uses an enzymatic reaction to create electrical signals that can be read directly from the array, there is no need for image analysis or for expensive and delicate optical scanning equipment. We show assay sensitivity and specificity that are excellent for a multiplexed format.     

A double blind, placebo-controlled study of Andrographis paniculata fixed combination Kan Jang in the treatment of acute upper respiratory tract infections including sinusitis.

A double blind, placebo-controlled, parallel-group clinical study was carried out to evaluate the effect of an Andrographis paniculata (N.) extract SHA-10 fixed combination, Kan Jang, in the treatment of acute upper respiratory tract infections, including sinusitis. Ninety-five individuals in the treatment group and 90 individuals in the placebo group completed the study according to the protocol. The medication was taken for 5 days. Temperature, headache, muscle aches, throat symptoms, cough, nasal symptoms, general malaise and eye symptoms were taken as outcome measures with given scores. The total score analysis showed a highly significant improvement in the verum group versus the placebo. This result applied to the group as a whole and to the sinusitis subgroups. The individual symptoms of headache and nasal and throat symptoms together with general malaise showed the most significant improvement while cough and eye symptoms did not differ significantly between the groups. Temperature was moderately reduced in the verum group. It can be concluded that Kan Jang has a positive effect in the treatment of acute upper respiratory tract infections and also relieves the inflammatory symptoms of sinusitis. The study drug was well tolerated.     

Pathogenic potential of environmental Klebsiella pneumoniae isolates

Klebsiella pneumoniae is an important opportunistic pathogen and a frequent cause of nosocomial infections. K. pneumoniae infections can occur at nearly any body site; however, urinary tract infections and infections of the respiratory tract predominate. Infections are frequently preceded by gastrointestinal colonization, and the gastrointestinal tract is believed to be the most important reservoir for transmission of the bacteria. In contrast to many other bacterial pathogens, K. pneumoniae is ubiquitous in nature. Several studies have described Klebsiella isolates of environmental origin to be nearly identical to clinical isolates with respect to several phenotypic properties. However, the pathogenic potential of environmental K. pneumoniae isolates is essentially unknown. We have evaluated the virulence of K. pneumoniae strains of environmental and clinical origin directly in animal models, i.e. in urinary tract infection and intestinal colonization models. Furthermore, the ability to adhere to and invade human epithelial cell lines was examined. Although strain-to-strain differences were observed in the individual infection models, overall, strains of environmental origin were found to be as virulent as strains of clinical origin. The ubiquity of K. pneumoniae in nature and the general ability of K. pneumoniae strains to infect susceptible hosts might explain the high frequency of opportunistic infections caused by this species.     

Genomic screening for Chlamydophila pneumoniae-specific antigens using serum samples from patients with primary infection

Chlamydophila pneumoniae, an obligate intracellular human pathogen, causes respiratory tract infections. The most common techniques used for the serological diagnosis of C.?pneumoniae infections are microimmunofluorescence tests and commercial serological ELISA tests; these are based on the detection of antibodies against whole chlamydial elementary bodies and lipopolysaccharide/outer membrane protein, respectively. Identification of more specific and highly immunodominant antigens is essential for the development of new serodiagnostic assays. To identify novel specific antigens from C.?pneumoniae, we screened 455 genes with unknown function in the genome of C.?pneumoniae J138. Extracts of Saccharomyces cerevisiae cells expressing GFP-tagged C.?pneumoniae proteins were subjected to Western blot analysis using serum samples from C.?pneumoniae-infected patients as the primary antibodies. From this comprehensive analysis, 58 clones expressing C.?pneumoniae open reading frames, including hypothetical proteins, were identified as antigens. These results have provided useful information for the development of new serological tools for the diagnosis for C.?pneumoniae infections and for the development of vaccines in future.