Prevalence of Pneumonia due to &lt;i&gt;Legionella pneumophila&lt;/i&gt; and &lt;i&gt;Mycoplasma pneumoniae&lt;/i&gt; in a Population Admitted to a Department of Internal Medicine

Bozzoni, Mauro; Radice, L.; Frosi, A.; Vezzoli, Stefano; Cuboni, Andrea; Vezzoli, Francesco

doi:10.1159/000196475

Cited by 8 publications

(5 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In evaluating the extent of atypical respiratory agents in our patients we found that specific sputum and BAL cultures for L. pneumophilia were positive in 5%, as were cultures for M. pneumoniae. Other studies give variable positivity rates for these organisms, ranging from 1% to 27 % [16,17]. Positive culture rates for these atypical pathogens more than likely depend on the patient population, socioeconomic factors, age, and possibility of exposure.…”

Section: Discussionmentioning

confidence: 99%

Clinico-pathological study of atypical pathogens in community-acquired pneumonia: a prospective study

Zaki

Goda

2009

J Infect Dev Ctries

View full text Add to dashboard Cite

Background Atypical respiratory pathogens such as Mycoplasma pneumoniae, Legionella species, and Chlamydia pneumoniae are isolated with increasing frequency from community-acquired pneumonia (CAP). This study highlights the importance of organisms responsible for CAP. Methodology: One hundred consecutive patients with clinically and radiographically diagnosed CAP were evaluated from October 2005 to October 2006. Sputum, bronchoalveolar lavage, and blood samples were collected for microbiological culture. Determination was performed for specific immunoglobulin M (IgM) for Chlamydia pneumoniae, Mycoplasma pneumoniae, Legionella pneumophila, Coxiella burnettii, adenovirus, and influenza virus. Results: The most common isolated bacteria was Streptococcus pneumoniae (22%) followed by Haemophilus influenzae (18%). Mycoplasma pneumoniae was isolated from 5% and Legionella pneumophila was isolated from 5% of patients. The most common positive serological reaction was for Chlamydia pneumoniae (30%) and Adenovirus (30%). In the study of accuracy of determination of specific IgM for Mycoplasma pneumoniae and Legionella pneumophila compared to culture, the sensitivity was 60% and 80% respectively, specificity was 93.7 %, and 98.9 % respectively, and accuracy was 92 % and 97 % respectively. Conclusion: This study highlights the prominence of mixed bacterial/viral infections in lower respiratory tract infection diagnosis. Our data showed that at least 30% of our patients had concurrent infections. This observation raises two important questions: 1) whether sequential or concurrent viral and bacterial infections have a synergistic impact on the evolution of disease in children; and 2) should diagnostic batteries for any patient with CAP include methods for detecting both the typical and atypical bacterial or viral pathogens.

show abstract

Section: Discussionmentioning

confidence: 99%

Clinico-pathological study of atypical pathogens in community-acquired pneumonia: a prospective study

Zaki

Goda

2009

J Infect Dev Ctries

View full text Add to dashboard Cite

show abstract

“…Legionella pneumophila, the causative agent of Legionnaires' disease, is recognized as a major cause of community and nosocomial epidemic pneumonia (8,13,26). The ability of L. pneumophila to cause disease is dependent on its ability to invade and replicate within human alveolar cells.…”

mentioning

confidence: 99%

Characterization of a Macrophage-Specific Infectivity Locus ( milA ) of Legionella pneumophila

Harb

Kwaik

2000

Infect Immun

View full text Add to dashboard Cite

Legionella pneumophila has been shown to possess multiple genetic loci that play roles in its ability to survive within host cells. The mil (macrophage-specific infectivity loci) mutants of L. pneumophila exhibit a spectrum of defects in intracellular survival in and cytopathogenicity to macrophages and alveolar epithelial cells. This study characterizes one of the mil mutants (GB111). Intracellular growth of GB111 in macrophages was approximately 100-to 1,000-fold less than that of AA100, the parental strain, at 24 and 48 h postinfection. This defect in turn corresponded to a defect in cytopathogenicity. Sequence analysis of the affected GB111 open reading frame (ORF) revealed it to encode a putative transport protein, and the ORF was designated milA. The phenotypic defect of the milA mutant was complemented with a PCR fragment containing only milA, indicating that the defect in GB111 was due to the disruption of milA. Intracellular trafficking of the mutant was examined by laser scanning confocal microscopy. The data showed that 50% of the GB111 phagosomes colocalized with the late endosomal/lysosomal marker LAMP-2 (2 and 4 h postinfection), while less than 10% of the AA100 phagosomes colocalized with this marker. On the other hand, over 80% of the GB111 phagosomes were similar to the AA100 phagosome in that they were devoid of LAMP-1 and cathepsin D, and they were colocalized with the endoplasmic reticulum (ER) marker BiP. However, the number of GB111 phagosomes that colocalized with BiP decreased to 50% 6 h postinfection compared to that of AA100, which remained constant (80% colocalization). Thus, compared to AA100, the milA mutation caused a defect in intracellular replication, which was associated with colocalization of the phagosome with LAMP-2 and BiP, while colocalization with LAMP-1 and cathepsin D was not affected.

show abstract

“…Legionnaires' disease is a common pneumonia that occurs in both nosocomial and community settings (14,19,41). In the lungs of affected individuals, L. pneumophila replicates in phagocytic and possibly alveolar epithelial cells, within a specialized compartment that is surrounded by the host-cell rough endoplasmic reticulum (RER) and mitochondria (1,24,39,51,62).…”

mentioning

confidence: 99%

Essential Role for the Legionella pneumophila Rep Helicase Homologue in Intracellular Infection of Mammalian Cells

Harb

Kwaik

2000

Infect Immun

View full text Add to dashboard Cite

We have previously isolated 32 mutants of Legionella pneumophila that are defective in the infection of mammalian cells but not protozoa. The mutated loci have been designated macrophage-specific infectivity (mil) loci. In this study we characterized the mil mutant GK11. This mutant was incapable of growth within U937 macrophage-like cells and WI-26 alveolar epithelial cells. This defect in intracellular replication correlated with a defect in cytopathogenicity to these cells. Sequence analysis of the GK11 locus revealed it to be highly similar to rep helicase genes of other bacteria. Since helicase mutants of Escherichia coli are hypersensitive to thymine starvation, we examined the sensitivity of GK11 to thymineless death (TLD). In the absence of thymine and thymidine, mutant GK11 did not undergo TLD but was defective for in vitro growth, and the defect was partially restored when these compounds were added to the growth medium. In addition, supplementation with thymidine or thymine partially restored the ability of GK11 to grow within and kill U937 macrophage-like cells. The data suggested that the low levels of thymine or thymidine in the L. pneumophila phagosome contributed to the defect of GK11 within macrophages. Using confocal laser scanning microscopy, we determined the effect of the mutation in the Rep helicase homologue on the intracellular trafficking of GK11 within macrophages. In contrast to the wild-type strain, phagosomes harboring GK11 colocalized with several late endosomal/lysosomal markers, including LAMP-1, LAMP-2, and cathepsin D. In addition, only 50% of the GK11 phagosomes colocalized with the endoplasmic reticulum marker BiP 4 h postinfection. Colocalization of BiP with GK11 phagosomes was absent 6 h postinfection, while 90% of the wild-type phagosomes colocalized with this marker at both time points. We propose that the low level of thymine within the L. pneumophila phagosome in combination with simultaneous exposure to multiple stress stimuli results in deleterious mutations that cannot be repaired in the rep helicase homologue mutant, rendering it defective in intracellular replication.

show abstract

Prevalence of Pneumonia due to <i>Legionella pneumophila</i> and <i>Mycoplasma pneumoniae</i> in a Population Admitted to a Department of Internal Medicine

Cited by 8 publications

References 8 publications

Clinico-pathological study of atypical pathogens in community-acquired pneumonia: a prospective study

Clinico-pathological study of atypical pathogens in community-acquired pneumonia: a prospective study

Characterization of a Macrophage-Specific Infectivity Locus ( milA ) of Legionella pneumophila

Essential Role for the Legionella pneumophila Rep Helicase Homologue in Intracellular Infection of Mammalian Cells

Contact Info

Product

Resources

About