Atypical Pneumonia: Updates on Legionella, Chlamydophila, and Mycoplasma Pneumonia

Imaging of pulmonary infections encountered in the emergency department in post-COVID 19 era- common, rare and exotic. Bacterial and viral

Pulmonary infections contribute substantially to emergency department (ED) visits, posing a considerable health burden. Lower respiratory tract infections are prevalent, particularly among the elderly, constituting a significant percentage of infectious disease-related ED visits. Timely recognition and treatment are crucial to mitigate morbidity and mortality. Imaging studies, primarily chest radiographs and less frequently CT chests, play a pivotal role in diagnosis. This article aims to elucidate the imaging patterns of both common and rare pulmonary infections (bacterial and viral) in the post COVID-19 era, emphasizing the importance of recognizing distinct radiological manifestations. The integration of clinical and microbiological evidence aids in achieving accurate diagnoses, and guiding optimal therapeutic interventions. Despite potential overlapping manifestations, a nuanced understanding of radiological patterns, coupled with comprehensive clinical and microbiological information, enhances diagnostic precision in majority cases.

Impact of azithromycin, doxycycline and redox-active small molecules on amoxicillin-induced Chlamydia pneumoniae persistence

Amoxicillin is recommended as primary treatment for community-acquired bacterial pneumonia (CABP). 5-10% of CABP cases are caused by Chlamydia pneumoniae, an obligate intracellular bacterium which responds to beta-lactam antibiotics by converting to a persistent phenotype. To support rational pharmacotherapy of C. pneumoniae infections, we investigated how clinically relevant concentrations of azithromycin and doxycycline affect amoxicillin induced C. pneumoniae persistence. Given the known role of redox state alterations in the action of bactericidal antibiotics and widespread use of redox-active dietary supplements when experiencing respiratory symptoms, we also studied how redox active compounds affect the studied antibiotic treatments. Our data demonstrate that clinically applied amoxicillin concentrations (10 and 25 mg/l) fail to eradicate C. pneumoniae infection in respiratory epithelial cells. Transmission electron microscopy (TEM) of amoxicillin-treated C. pneumoniae infected cells reveal aberrant bacterial morphology characteristic of chlamydial stress response. Amoxicillin was also found to significantly limit the antichlamydial effect of azithromycin or doxycycline. However, based on quantitative culture and quantitative PCR data, azithromycin was superior to doxycycline in C. pneumoniae eradication either as monotherapy or in combination with amoxicillin. Amoxicillin was also found to decrease respiratory epithelial cell glutathione (GSH) levels, whereas redox-active dibenzocyclooctadiene lignans increased C. pneumoniae load in amoxicillin-treated cultures up to two-fold. These data highlight the impact of relative administration time on the efficacy of antichlamydial antibiotics and indicate unfavorable interactions between amoxicillin and redox-active small molecules.

Hairy Cell Leukemia (HCL) Presenting As Severe Acute Respiratory Distress Syndrome (ARDS) With Legionella pneumophila: Coincidence or Causation?

Due to a low index of suspicion coupled with specific growth conditions and non-specific clinical manifestations, Legionella (L.) pneumophila is a frequently misdiagnosed cause of pneumonia in immunocompromised patients, especially those with hematological malignancies. We present a case of severe acute respiratory distress syndrome (ARDS) secondary to Legionnaire's disease in a patient with newly diagnosed hairy cell leukemia (HCL) to highlight the importance of early recognition, diagnosis, and treatment of Legionnaire's disease to reduce morbidity and mortality.

The incidence of acute renal failure and high mortality rate in elderly patients hospitalized with community acquired pneumonia

Community acquired pneumonia is associated with high mortality and health care costs, especially in old age. The clinical presentation of pneumonia in the elderly may be asymptomatic or atypical. One of the known complication is an acute kidney injury. The purpose of our study was to estimate the incidence of this complication in elderly patients hospitalized with pneumonia in our geriatric hospital. From a group of 180 elderly patients hospitalized with community-acquired pneumonia 34.4 % developed acute kidney injury. In this group, 51.6 % of patients died compared to 14.4 % in the group of patients without acute kidney injury (p < 0.001). The lower level of e-GFR was significantly associated with mortality (p < 0.001): out of seven patients with e-GFR level of 15-29 mg/mmol, five patients died (71.4 %). Elderly patients with community-acquired pneumonia suffering acute kidney injury experienced worse in-hospital outcomes; mortality rate was significantly higher in our study. We found a relationship between low level of e-GFR and mortality. Clinicians should be alert for early detection and prevention of kidney injury in patients admitted with pneumonia.

Atraumatic Splenic Rupture in Legionella pneumophila Pneumonia

A previously fit 46-year-old male handyman presented to a rural hospital with a cough, fever, and epigastric pain without peritonism. The patient was admitted medically with symptoms and radiological appearances consistent with atypical community-acquired pneumonia. During the first 48 hours of admission, he suffered a significant haemodynamic deterioration and was transferred to the intensive care unit (ICU) for vasoactive support. Following stabilisation, urgent abdominal CT imaging demonstrated splenic rupture with haematoma in the absence of historical trauma. Emergency splenectomy was performed; the histopathological examination was unremarkable. Investigations for the presenting complaint confirmed Legionella pneumophila serotype 1 pneumonia by urinary antigen testing. The patient was extubated on postoperative day 2 and stepped down from ICU to complete a 14-day course of azithromycin. Atraumatic splenic rupture is a rarely described clinical entity. The process can be subdivided into pathological and nonpathological (spontaneous) cases. Pathological atraumatic splenic rupture may occur in the context of wide-ranging aetiologies, including bacterial pneumonia; however, the association with Legionella pneumophila serotype 1 is exceptional, with this representing the eighth case in the medical literature.

Use of niosomes for the treatment of intracellular pathogens infecting the lungs

The delivery of drugs in an encapsulated environment is designed to precisely target specific tissues, avoiding a systemic circulation of the drug. Lungs are organs exposed to the environment with multiple defense barriers. However, many pathogens can still colonize and infect the airways bypassing the hostile environment of the lungs. In more complicated situations, some pathogens have developed strategies to multiply and survive within macrophages, one of the first immune cell responses to clearing infections in mammals. Niosomes are artificial vesicles that can be loaded with drugs, offering an alternative strategy to treat intracellular pathogens as nanocarriers. Members of the mycobacteria genus are intracellular pathogens that have evolved to escape the immunological response, specifically in macrophages, the white cells responsible for the clearance of pathogens. This review analyzed the state-of-the-art niosome synthesis aimed at tackling the problem of intracellular pathogen therapy. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious Disease Nanotechnology Approaches to Biology > Nanoscale Systems in Biology.

Identification and comparison of Chlamydia psittaci, Legionella and Mycoplasma pneumonia infection

INTRODUCTION

Conventional etiological detection and pathogenic antibody methods make it challenging to identify the atypical pathogens among the community-acquired pneumonia (CAP). Metagenomic next-generation sequencing (mNGS) could rapidly detect all potentially infectious diseases and identifies novel or potential pathogens.

METHODS

Eighteen patients diagnosed with atypical CAP were enrolled in this retrospective study, including nine Chlamydia psittaci pneumonia (C. p), four Legionella pneumonia (L. p) and five Mycoplasma pneumonia (M. p). We simultaneously tested bronchoalveolar lavage fluid (BALF) samples for conventional microbiological methods and mNGS, and blood specimens were analysed. We also collected and compared baseline and clinical characteristics and treatment responses.

RESULTS

Patients with C. p and L. p had similar symptoms, including fever, cough, headache, dyspnoea, asthenia, shivering and headache, compared with M. p, whose symptoms were slight. C. p and L. p usually showed multiple lobar distributions with pleural effusion. Serologic testing indicated that L. p had higher levels of white blood cells (WBCs), neutrophils, C-reactive protein (CRP), procalcitonin (PCT), alanine aminotransferase (ALT), lactate dehydrogenase (LDH) and creatinine compared with M. p and L. p (p < 0.05). However, patients with C. p had lower levels of albumin (p < 0.05), and M. p had a minimum risk of cardiac volume loads (p < 0.05). CD4/CD8 ratio, lymphocytes, aspartate aminotransferase (AST), creatine kinase (CK), cell counting of BALF and coagulation had no difference (p < 0.05). Pathogenic IgM assay showed that 4/5 cases were positive for M. p and no positive detection for C. p and L. p infection. We timely adjusted the antibiotics according to the final mNGS results. Eventually, 16/18 patients recovered fully. Conditions of L. p patients were worse than those of C. p patients, and those of M. p patients were the least.

CONCLUSION

Early application of mNGS detection increased the atypical pathogenic identification, improved the prognosis and made up for the deficiency of conventional detection methods.

Central and effector memory T cells in peripheral blood of patients with interstitial pneumonia: preliminary clues from a COVID-19 study

BACKGROUND

SARS-CoV-2 pre-existing T-cell immune reactivity can be present in some people. A general perturbation of the main peripheral lymphocyte subsets has been described in severe COVID-19 patients, but very few studies assessed the general memory T-cell homeostasis in the acute phase of COVID-19. Here, we performed a general analysis of the main memory T cell populations in the peripheral blood of patients admitted to the hospital for a confirmed or probable COVID-19 diagnosis.

METHODS

In this cross-sectional study, adult patients (aged ≥ 18 years) needing hospital admission for respiratory disease due to confirmed or probable COVID-19, were recruited before starting the therapeutic protocol for this disease. In addition to the assessment of the general lymphocyte subpopulations in the early phase of COVID-19, central memory T cells (Tm_centr cells: CD45RO+CCR7+) and effector memory T cells (Tm_eff cells: CD45RO+CCR7-) were assessed by multi-color flow cytometry, in comparison to a control group.

RESULTS

During the study period, 148 study participants were recruited. Among them, 58 patients turned out positive for SARS-CoV-2 PCR (including both patients with interstitial pneumonia [PCR+Pn+] and without this complication [PCR+Pn-]), whereas the remaining 90 patients resulted to be SARS-CoV-2 PCR negative, even though all were affected with interstitial pneumonia [PCR-Pn+]. Additionally, 28 control patients without any ongoing respiratory disease were recruited. A clear unbalance in the T memory compartment emerged from this analysis on the whole pool of T cells (CD3+ cells), showing a significant increase in Tm_centr cells and, conversely, a significant decrease in Tm_eff cells in both pneumonia groups (PCR+Pn+ and PCR-Pn+) compared to the controls; PCR+Pn- group showed trends comprised between patients with pneumonia (from one side) and the control group (from the other side). This perturbation inside the memory T cell compartment was also observed in the individual analysis of the four main T cell subpopulations, based upon the differential expression of CD4 and/or CD8 markers.

CONCLUSION

Overall, we observed both absolute and relative increases of Tm_centr cells and decrease of Tm_eff cells in patients affected with interstitial pneumonia (regardless of the positive or negative results of SARS-CoV-2 PCR), compared to controls. These results need confirmation from additional research, in order to consider this finding as a potential biological marker of interstitial lung involvement in patients affected with viral respiratory infections.

Legionnaire’s Disease Presenting With the Legionella Triad (Pneumonia, Rhabdomyolysis, and Renal Failure) and Cardiac Complications

Legionella pneumonia is well-characterized as a cause of atypical, community-acquired pneumonia in susceptible individuals. In recent years, extrapulmonary manifestations, including an emerging triad of Legionella pneumonia, rhabdomyolysis, and renal failure, have been identified. Here we report a case of Legionnaire's disease that presented non-classically, with subclinical pneumonia and non-ST elevated myocardial infarction (NSTEMI). Although he received early treatment with antibiotics, he developed the Legionellatriad during admission. He had several episodes of cardiopulmonary decompensation during his hospital course, eventually ending in his passing. This case serves to highlight the importance of early identification and intervention in regard to extrapulmonary Legionella infection.

Diagnosis and Prognostic Analysis of Mycoplasma pneumoniae Pneumonia in Children Based on High-Resolution Computed Tomography

Mycoplasma pneumoniae (MP) is defined as a common cause of pulmonary infections and accounts for up to four over ten of pneumonia in children over age 5. This study was aimed to explore the diagnosis and prognosis of mycoplasma pneumoniae pneumonia (MPP) in children using high-resolution computed tomography (CT) (HRCT). 71 children hospitalized with MPP were undertaken as the research objects to observe the incidence rate, occurrence time, and duration of the clinical symptoms and pathological signs. The chest HRCT and pulmonary ventilation function (PVF) were examined in the acute phase, the second phase re-examination period, and the third phase re-examination period. Relevant indicators were statistically analyzed to determine the change rules of chest HRCT and PVF and correlation between the two. Clinically, the children with MPP suffered from fever, cough, and sore throat. In addition to the above symptoms, children with MPP had different degrees of PVF impairment. Compared with the group with normal HRCT results, the forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), peak expiratory flow (PEF), forced expiratory flow at 25% forced expiratory volume (FEF25), forced expiratory flow at 50% forced expiratory volume (FEF50), forced expiratory flow at 75% forced expiratory volume (FEF75), and maximum mid-expiratory flow (MMEF75/25) of children in bronchopneumonia group, segmental pneumonia group, and lobar pneumonia group were obviously reduced, showing statistically great differences (P < 0.05). Compared with the case in acute phase, the PVF indicators of children in the re-examination phases were much higher, with greatly statistical differences (P < 0.05). In children with MPP, both the large and small airways were affected, but the recovery of the small airways was slow. Pulmonary HRCT and PVF can be undertaken as important indicators to judge the severity and prognosis of MPP in school-age children.

Beyond the approved: target sites and inhibitors of bacterial RNA polymerase from bacteria and fungi

Covering: 2016 to 2022RNA polymerase (RNAP) is the central enzyme in bacterial gene expression representing an attractive and validated target for antibiotics. Two well-known and clinically approved classes of natural product RNAP inhibitors are the rifamycins and the fidaxomycins. Rifampicin (Rif), a semi-synthetic derivative of rifamycin, plays a crucial role as a first line antibiotic in the treatment of tuberculosis and a broad range of bacterial infections. However, more and more pathogens such as Mycobacterium tuberculosis develop resistance, not only against Rif and other RNAP inhibitors. To overcome this problem, novel RNAP inhibitors exhibiting different target sites are urgently needed. This review includes recent developments published between 2016 and today. Particular focus is placed on novel findings concerning already known bacterial RNAP inhibitors, the characterization and development of new compounds isolated from bacteria and fungi, and providing brief insights into promising new synthetic compounds.

Study on the Therapeutic Effect of Azithromycin Combined with Glucocorticoid on Pulmonary Function and Inflammatory Response in Children with Pneumonia

Objective

The objective is to explore the efficacy of azithromycin combined with glucocorticoids in the treatment of children with pneumonia and its effect on the inflammatory response.

Methods

A total of 86 children with pneumonia were divided into the experimental group (EG) and the control group (CG). Both groups received conventional treatment, the CG was treated with azithromycin and the EG was additionally treated with glucocorticoid methylprednisolone. The therapeutic effect, disappearance time of clinical symptoms, pulmonary function, inflammatory factors, immune function, quality of life, and adverse reactions were measured in the two groups.

Results

After treatment, compared with CG, the total effective rate was significantly elevated, the disappearance time of various clinical symptoms was earlier, and various pulmonary function indexes were increased in the EG. The interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), C reactive protein (CRP), and CD8+ levels were reduced, and CD3+ and CD4+ levels were increased in the EG. The quality-of-life scores were upregulated in the EG. Moreover, there was no significant difference in the incidence of adverse reactions between the two groups.

Conclusion

The combined use of azithromycin and glucocorticoids in the treatment of children with Mycoplasma pneumoniae infection has a good curative effect, can significantly improve lung function, restore pulmonary inflammatory indexes to normal, and enhance patients' immune function and improve their quality of life, with fewer adverse reactions and safety.

Effect Evaluation of Artificial Intelligence-Based Electronic Health PDCA Nursing Model in the Treatment of Mycoplasma Pneumonia in Children

The PDCA cycle, also known as Deming's cycle, mainly includes four stages: planning, implementation, inspection, and processing. As a kind of atypical pneumonia with fever and cough, mycoplasma pneumonia harms the health of many children. The purpose of this study is to investigate the anti-inflammatory and antimycoplasma effects and safety of artificial intelligence e-health PDCA nursing mode on pediatric MPP, to investigate its clinical efficacy, to observe the changes of serum cytokines (IL-10, IL-2, IL-4, IFN-γ), and to explore the mechanism of action and possible targets for the treatment of MPP, to provide a new basis for clinical treatment of MPP. The experimental results show that in the experimental group using PDCA nursing mode, the total satisfaction is 97.22%, higher than the control group of 94.44%; in the experimental group, the hospital stay and symptom disappearance time were significantly shortened by four hours. The satisfaction of nursing staff was significantly increased in statistical significance (P < 0.05). Therefore, in a statistical sense, the artificial intelligence e-health PDCA nursing mode can significantly improve the clinical symptoms of MPP children with wind-heat stagnation of lung syndrome and phlegm-heat closure of lung syndrome, improve the treatment effect of childhood mycoplasma pneumonia epidemic, shorten the time of hospitalization and symptom disappeared, and play a great auxiliary role in the treatment of childhood mycoplasma pneumonia.

Overview of the Clinical and Molecular Features of Legionella Pneumophila: Focus on Novel Surveillance and Diagnostic Strategies

Legionella pneumophila (L. pneumophila) is one of the most threatening nosocomial pathogens. The implementation of novel and more effective surveillance and diagnostic strategies is mandatory to prevent the occurrence of legionellosis outbreaks in hospital environments. On these bases, the present review is aimed to describe the main clinical and molecular features of L. pneumophila focusing attention on the latest findings on drug resistance mechanisms. In addition, a detailed description of the current guidelines for the disinfection and surveillance of the water systems is also provided. Finally, the diagnostic strategies available for the detection of Legionella spp. were critically reviewed, paying the attention to the description of the culture, serological and molecular methods as well as on the novel high-sensitive nucleic acid amplification systems, such as droplet digital PCR.

Traditional Medicinal Plants—A Possible Source of Antibacterial Activity on Respiratory Diseases Induced by Chlamydia pneumoniae, Haemophilus influenzae, Klebsiella pneumoniae and Moraxella catarrhalis

Background. Nowadays, phytotherapy offers viable solutions in managing respiratory infections, disorders known for considerable incidence in both children and adults. In a context in which more and more people are turning to phytotherapy, finding new remedies is a topical goal of researchers in health and related fields. This paper aims to identify those traditional medicinal plants that show potentially antibacterial effects against four Gram-negative germs (Chlamydia pneumoniae, Haemophilus influenzae, Klebsiella pneumoniae, and Moraxella catarrhalis), which are considered to have high involvement in respiratory infections. Furthermore, a comparison with Romanian folk medicines was performed. Methods. An extensive review of books and databases was undertaken to identify vegetal species of interest in the context of the topic. Results. Some traditional Romanian species (such as Mentha × piperita, Thymus vulgaris, Pinus sylvestris, Allium sativum, Allium cepa, Ocimum basilicum, and Lavandulaangustifolia) were identified and compared with the plants and preparations confirmed as having antibacterial effects against specific germs. Conclusions. The antibacterial effects of some traditionally used Romanian medicinal plants are poorly investigated, and deserve further attention.

Septic shock due to co-infection with Legionella pneumophila and Saprochaete clavata

Septic shock is the most dreaded presentation of an infection, carrying a reserved prognosis. Appropriate antimicrobial therapy is therefore the mainstay of treatment, alongside organ support as needed. Legionnaires' disease is mainly due to Legionella pneumophila serogroup 1 but it can be caused by other serogroups and species not detected by the urinary antigen test. Anti-tumour necrosis factor α therapy may increase the risk of invasive fungal infection, which carry a poor prognosis. We present a challenging case of a septic shock due to Legionella pneumophila and Saprochaete clavata infections, with a review of the two infections presented.

Lefamulin in Patients with Community-Acquired Bacterial Pneumonia Caused by Atypical Respiratory Pathogens: Pooled Results from Two Phase 3 Trials

Lefamulin was the first systemic pleuromutilin antibiotic approved for intravenous and oral use in adults with community-acquired bacterial pneumonia based on two phase 3 trials (Lefamulin Evaluation Against Pneumonia [LEAP]-1 and LEAP-2). This pooled analysis evaluated lefamulin efficacy and safety in adults with community-acquired bacterial pneumonia caused by atypical pathogens (Mycoplasma pneumoniae, Legionella pneumophila, and Chlamydia pneumoniae). In LEAP-1, participants received intravenous lefamulin 150 mg every 12 h for 5–7 days or moxifloxacin 400 mg every 24 h for 7 days, with optional intravenous-to-oral switch. In LEAP-2, participants received oral lefamulin 600 mg every 12 h for 5 days or moxifloxacin 400 mg every 24 h for 7 days. Primary outcomes were early clinical response at 96 ± 24 h after first dose and investigator assessment of clinical response at test of cure (5–10 days after last dose). Atypical pathogens were identified in 25.0% (91/364) of lefamulin-treated patients and 25.2% (87/345) of moxifloxacin-treated patients; most were identified by ≥1 standard diagnostic modality (M. pneumoniae 71.2% [52/73]; L. pneumophila 96.9% [63/65]; C. pneumoniae 79.3% [46/58]); the most common standard diagnostic modality was serology. In terms of disease severity, more than 90% of patients had CURB-65 (confusion of new onset, blood urea nitrogen > 19 mg/dL, respiratory rate ≥ 30 breaths/min, blood pressure <90 mm Hg systolic or ≤60 mm Hg diastolic, and age ≥ 65 years) scores of 0–2; approximately 50% of patients had PORT (Pneumonia Outcomes Research Team) risk class of III, and the remaining patients were more likely to have PORT risk class of II or IV versus V. In patients with atypical pathogens, early clinical response (lefamulin 84.4–96.6%; moxifloxacin 90.3–96.8%) and investigator assessment of clinical response at test of cure (lefamulin 74.1–89.7%; moxifloxacin 74.2–97.1%) were high and similar between arms. Treatment-emergent adverse event rates were similar in the lefamulin (34.1% [31/91]) and moxifloxacin (32.2% [28/87]) groups. Limitations to this analysis include its post hoc nature, the small numbers of patients infected with atypical pathogens, the possibility of PCR-based diagnostic methods to identify non-etiologically relevant pathogens, and the possibility that these findings may not be generalizable to all patients. Lefamulin as short-course empiric monotherapy, including 5-day oral therapy, was well tolerated in adults with community-acquired bacterial pneumonia and demonstrated high clinical response rates against atypical pathogens.

Chlamydia pneumoniae-associated pleuropericarditis: a case report and systematic review of the literature

BACKGROUND

Chlamydia pneumoniae is a common cause of atypical community acquired pneumonia (CAP). The diagnostic approach of chlamydial infections remains a challenge. Diagnosis of delayed chlamydial-associated complications, involving complex autoimmune pathophysiological mechanisms, is still more challenging. C. pneumoniae-related cardiac complications have been rarely reported, including cases of endocarditis, myocarditis and pericarditis.

CASE PRESENTATION

A 40-year old female was hospitalized for pleuropericarditis following lower respiratory tract infection. The patient had been hospitalized for CAP (fever, dyspnea, chest X-ray positive for consolidation on the left upper lobe) 5 weeks ago and had received ceftriaxone and moxifloxacin. Four weeks after her discharge, the patient presented with fever, shortness of breath and pleuritic chest pain and was readmitted because of pericardial and bilateral pleural effusions (mainly left). The patient did not improve on antibiotics and sequential introduction of colchicine and methylprednisolone was performed. The patient presented impressive clinical and laboratory response. Several laboratory and clinical assessments failed to demonstrate any etiological factor for serositis. Chlamydial IgM and IgG antibodies were positive and serial measurements showed increasing kinetics for IgG. Gold standard polymerase chain reaction of respiratory tract samples was not feasible but possibly would not have provided any additional information since CAP occurred 5 weeks ago. The patient was discharged under colchicine and tapered methylprednisolone course. During regular clinic visits, she remained in good clinical condition without pericardial and pleural effusions relapse.

CONCLUSIONS

C. pneumoniae should be considered as possible pathogen in case of pleuritis and/or pericarditis during or after a lower respiratory tract infection. In a systematic review of the literature only five cases of C. pneumoniae associated pericarditis were identified. Exact mechanisms of cardiovascular damage have not yet been defined, yet autoimmune pathways might be implicated.

Treatment of legionellosis including a single intravenous dose of 1.5 g azithromycin: 18-year experience at a tertiary care hospital

OBJECTIVES

Due to recent safety concerns regarding fluoroquinolones and the potential medical and economic benefits, we investigated the efficacy of a single intravenous dose of 1.5 g azithromycin for the treatment of pulmonary legionellosis.

METHODS

Using a nationwide legionellosis registry for pre-selection, 74 patients admitted from 2000-2018 to a tertiary care hospital owing to pneumonia caused by Legionella pneumophila were retrospectively included in this study.

RESULTS

Conventional treatment regimens consisting of fluoroquinolones (n = 20), macrolides (n = 30) or combinations of both (n = 24) and a single intravenous dose of azithromycin (n = 12) have been demonstrated to be equally effective. Single-dose azithromycin treatment was well tolerated and resulted in a shorter hospital stay (P = 0.0464) and shorter antibiotic treatment duration (P = 0.0004) allowing earlier discharge.

CONCLUSION

A single intravenous dose of azithromycin might be a valuable treatment alternative for patients with legionellosis.

Rifamycin antibiotics and the mechanisms of their failure

Rifamycins are a class of antibiotics that were first discovered in 1957 and are known for their use in treating tuberculosis (TB). Rifamycins exhibit bactericidal activity against many Gram-positive and Gram-negative bacteria by inhibiting RNA polymerase (RNAP); however, resistance is prevalent and the mechanisms range from primary target modification and antibiotic inactivation to cytoplasmic exclusion. Further, phenotypic resistance, in which only a subpopulation of bacteria grow in concentrations exceeding their minimum inhibitory concentration, and tolerance, which is characterized by reduced rates of bacterial cell death, have been identified as additional causes of rifamycin failure. Here we summarize current understanding and recent developments regarding this critical antibiotic class.

Occurrence of the Legionella species in the respiratory samples of patients with pneumonia symptoms from Ahvaz, Iran; first detection of Legionella cherrii

BACKGROUND

This study aimed to investigate the occurrence of Legionella species in the respiratory samples of patients with pneumonia symptoms from Ahvaz, Iran by culture and the real-time PCR of 23S-5S rRNA gene spacer region.

METHODS AND RESULTS

A total of 123 clinical respiratory samples including 63 pleural aspirates, 57 bronchoalveolar lavage (BAL), and 3 sputum were collected from 65 males and 58 females with pneumonia symptoms. All samples were cultured on the Modified Wadowsky-Yee (MWY) agar. The Legionella species was identified by routine bacteriological tests. The presence of the 16S-23S rRNA spacer region gene was investigated by real-time PCR. The Legionella species were differentiated by sequencing of 16S-23S rRNA gene. A total of 2 (1.6%) BAL specimens were positive for Legionella species by culture method. No Legionella spp. were identified in pleural aspirates and sputum samples by the culture method. Using real-time PCR, 9 (7.3%) samples including 6 BAL, 1 sputum, and 2 pleural aspirates were positive for legionella species. These species were detected in 3 (5.2%) females and 6 males (9.2%). The results of sequencing showed that eight species were L. pneumophila while one was L. cherrii. Also, the 2 isolates that were identified by culture method, were confirmed as L. pneumophila by sequencing.

CONCLUSIONS

The results showed that using the real-time PCR has a more efficacy for detecting of Legionella species in respiratory samples. Also, L. pneumophila was the most prevalent species circulating in the southwest region of Iran. So, periodic monitoring programs is recommended to prevent epidemics due to this bacterium.

Efficacy of Empiric Antibiotic Coverage in Community-Acquired Pneumonia Associated with Each Atypical Bacteria: A Meta-Analysis

The benefit of empiric coverage for community-acquired pneumonia (CAP) for atypical bacteria is controversial. This meta-analysis purpose was to compare the clinical failure rate between adults who empirically received atypical coverage versus those who did not. We searched PubMed and EMBASE for randomized controlled trials (RCTs), comparing the clinical failure rate of CAP associated with individual atypical bacteria between adults who received empiric atypical coverage versus those who did not. Risk differences (RDs) with 95% confidence intervals (CIs) were calculated using random-effects models. Eight double-blind RCTs (65 patients with Legionella spp., 176 patients with M. pneumoniae, and 78 patients with C. pneumoniae) were included in the meta-analysis. The rate of clinical failure was significantly lower with empiric atypical coverage in CAP associated with Legionella spp. (RD, -42.6%; 95% CI, -69.8% to -15.4%; p-value = 0.002; I² = 0%) and Mycoplasma pneumoniae (RD, -9.5%; 95% CI, -18.9% to -0.1%; p-value = 0.048; I² = 0%), but not with Chlamydia pneumoniae (RD, 7.1%; 95% CI, -9.0% to 23.1%; p-value = 0.390; I² = 0%). This meta-analysis of RCTs found that empiric atypical coverage decreased the clinical failure rate of CAP associated with Legionella spp. and M. pneumoniae, but not with C. pneumoniae.

Community-acquired pneumonia: Trends in and research on drug resistance and advances in new antibiotics

Community-acquired pneumonia (CAP) refers to infectious inflammation of the lung parenchyma developing outside of a hospital. CAP has quite a high mortality and morbidity rate worldwide, and especially among elderly patients. The increasing burden of CAP is due to antibiotic resistance, the growth of the elderly population, and underlying comorbidities. Streptococcus pneumoniae remains the most common bacterial pathogen causing CAP, but multi-drug resistance bacteria and potential pathogens have increased the difficulty and challenges of managing CAP. Although preventive measures, diagnostic techniques, and treatment strategies are constantly advancing and improving, the susceptibility of multi-drug resistant pathogens, such as including Methicillin-Resistant Staphylococcus aureus (MRSA), Klebsiella pneumoniae, and Pseudomonas aeruginosa, has not improved significantly in recent decades, thus highlighting the importance and necessity of developing new antibiotics for the treatment of CAP. New antimicrobials have been approved over the past few years that will expand treatment options for CAP, and especially for patients with potential comorbidities. This situation also offers the chance to reduce the abuse of antibiotics, their toxicities, and their adverse reactions and to provide effective personalized antibiotic treatment.

Legionella Pneumonia on Point-of-care Ultrasound in the Emergency Department: A Case Report

Introduction

Legionella is an uncommon, atypical organism that can cause community-acquired pneumonia. Commonly associated with high fevers, gastrointestinal symptoms, and hyponatremia, it can be easily overlooked, especially during the coronavirus disease of 2019 (COVID-19) pandemic. Legionella has specific antibiotic treatment that will improve outcome; thus, its recognition is important.

Case Report

We present a case of Legionella pneumonia in a man presenting with shortness of breath and fever. The patient’s initial chest radiography was negative. With the use of point-of-care ultrasound (POCUS) the changes of atypical pneumonia could be seen. Ultimately Legionella was confirmed with urine antigen testing, and appropriate antibiotic treatment was started.

Discussion

Given the increased awareness of COVID-19 it is important to consider a broad differential with respiratory illness. Legionella pneumonia on POCUS is consistent with atypical pneumonia descriptions on ultrasound. Point-of-care ultrasound can be used to diagnose atypical pneumonia, specifically caused by Legionella in our case.

Conclusion

Legionella is evident on POCUS but is difficult to distinguish from other infections with POCUS alone. One should consider Legionella if POCUS is positive for signs of atypical infection.

Clinical manifestation, laboratory and radiology finding, treatment and outcomes of COVID-19: A systematic review and meta-analysis

BACKGROUND

Since December 2019, coronavirus (COVID-19) spread throughout the world. The high rate of infection and its unknown nature led specialists to report the condition of patients. The aim of this study is to systematically review of symptoms, laboratory and radiologic findings, treatment, and outcomes of patients with COVID-19.

MATERIALS AND METHODS

Databases such as PubMed, Embase, Scopus, Web of Science, Google Scholar, and Cochrane were searched. Finally, 46 articles were appropriate for the aim of the study. After quality evaluation, the necessary data were extracted and meta-analysis was performed.

RESULTS

4858 articles were retrieved until March 30, 2020. After screening, the full-text of 46 articles was assessed. Of the reported cases, 31.7% had no comorbidities, 21.4% had high blood pressure, 70.6% had fever, and lymphopenia was reported in 55.2% of patients. For 16% bilateral patchy shadowing in radiography and for 51% ground-glass opacity was reported. Outcomes were remarkable for recover to death.

CONCLUSION

COVID-19 leads to healthcare problems for countries. Nonspecific symptoms have made it difficult for differential diagnoses without computed tomography-scan or corona Test, but they are not available in many countries. Therefore, this systematic review can help health care staff to make decisions based on symptoms, treatments, and outcomes..

Atypical Pneumonia: Definition, Causes, and Imaging Features

Pneumonia is among the most common causes of death worldwide. The epidemiologic and clinical heterogeneity of pneumonia results in challenges in diagnosis and treatment. There is inconsistency in the definition of the group of microorganisms that cause "atypical pneumonia." Nevertheless, the use of this term in the medical and radiologic literature is common. Among the causes of community-acquired pneumonia, atypical bacteria are responsible for approximately 15% of cases. Zoonotic and nonzoonotic bacteria, as well as viruses, have been considered among the causes of atypical pneumonia in a patient who is immunocompetent and have been associated with major community outbreaks of respiratory infection, with relevant implications in public health policies. Considering the difficulty of isolating atypical microorganisms and the significant overlap in clinical manifestations, a targeted empirical therapy is not possible. Imaging plays an important role in the diagnosis and management of atypical pneumonia, as in many cases its findings may first suggest the possibility of an atypical infection. Clarifying and unifying the definition of atypical pneumonia among the medical community, including radiologists, are of extreme importance. The prompt diagnosis and prevention of community spread of some atypical microorganisms can have a relevant impact on local, regional, and global health policies. ^©RSNA, 2021.

Current perspectives on atypical pneumonia in children

The major pathogens that cause atypical pneumonia are Mycoplasma pneumoniae, Chlamydophila pneumoniae, and Legionella pneumophila. Community-acquired pneumonia (CAP) caused by M. pneumoniae or C. pneumoniae is common in children and presents as a relatively mild and self-limiting disease. CAP due to L. pneumophila is very rare in children and progresses rapidly, with fatal outcomes if not treated early. M. pneumoniae, C. pneumoniae, and L. pneumophila have no cell walls; therefore, they do not respond to β-lactam antibiotics. Accordingly, macrolides, tetracyclines, and fluoroquinolones are the treatments of choice for atypical pneumonia. Macrolides are the first-line antibiotics used in children because of their low minimum inhibitory concentrations and high safety. The incidence of pneumonia caused by macrolide-resistant M. pneumoniae that harbors point mutations has been increasing since 2000, particularly in Korea, Japan, and China. The marked increase in macrolide-resistant M. pneumoniae pneumonia (MRMP) is partly attributed to the excessive use of macrolides. MRMP does not always lead to clinical nonresponsiveness to macrolides. Furthermore, severe complicated MRMP responds to corticosteroids without requiring a change in antibiotic. This implies that the hyper-inflammatory status of the host can induce clinically refractory pneumonia regardless of mutation. Empirical macrolide therapy in children with mild to moderate CAP, particularly during periods without M. pneumoniae epidemics, may not provide additional benefits over β-lactam monotherapy and can increase the risk of MRMP.

Myositis and acute kidney injury in bacterial atypical pneumonia: Systematic literature review

BACKGROUND

Bacterial community-acquired atypical pneumonia is sometimes complicated by a myositis or by a renal parenchymal disease. Available reviews do not mention the concurrent occurrence of both myositis and acute kidney injury.

METHODS

In order to characterize the link between bacterial community-acquired atypical pneumonia and both myositis and a renal parenchymal disease, we reviewed the literature (United States National Library of Medicine and Excerpta Medica databases).

RESULTS

We identified 42 previously healthy subjects (35 males and 7 females aged from 2 to 76, median 42 years) with a bacterial atypical pneumonia associated both with myositis (muscle pain and creatine kinase ≥5 times the upper limit of normal) and acute kidney injury (increase in creatinine to ≥1.5 times baseline or increase by ≥27 μmol/L above the upper limit of normal). Thirty-six cases were caused by Legionella species (N = 27) and by Mycoplasma pneumoniae (N = 9). Further germs accounted for the remaining 6 cases. The vast majority of cases (N = 36) presented a diffuse myalgia. Only a minority of cases (N = 3) were affected by a calf myositis. The diagnosis of rhabdomyolysis-associated kidney injury was retained in 37 and that of acute interstitial nephritis in the remaining 5 cases.

CONCLUSION

Bacterial atypical pneumonia may occasionally induce myositis and secondary kidney damage.

Frequency of Mycoplasma pneumoniae, Legionella pneumophila and Chlamydia spp. among patients with atypical pneumonia in Tehran

Mycoplasma pneumoniae, Legionella pneumophila and Chlamydia pneumoniae are the most common bacterial agents, which account for 15-40%, 2-15% and 5-10% of atypical community-acquired pneumonia (CAP) respectively. These agents are mostly associated with infection in the outpatient setting. The aim of this study was to evaluate the frequency of these pathogens among patients with CAP attending outpatient clinics in Tehran. A cross-sectional study was carried out of 150 patients attending to educational hospitals in Tehran with CAP. M. pneumoniae, L. pneumophila and Chlamydia spp. were detected by PCR assay, targeting the P1 adhesion gene, macrophage infectivity potentiator (mip) gene and 16S rRNA gene respectively from throat swabs obtained from each patient. A total of 86 (57.3%) of 150 patients were women; median age was 50 years (interquartile range, 35-65 years). M. pneumoniae, L. pneumophila and Chlamydia spp. were detected in 37 (24.7%), 25 (16.7%) and 11 (7.3%) patients respectively; of these, 66 patients (44%) were infected at least by one of these three pathogens. The frequency of L. pneumophila was significantly higher among patients over 60 years old (p 0.03). Coinfection was detected in seven patients (4.7%); six were infected by M. pneumoniae and L. pneumophila, and only one was infected by L. pneumophila and Chlamydia spp. M. pneumoniae was the most prevalent agent of atypical CAP, and L. pneumophila was more likely to infect elderly rather than younger people. Further studies on the prevalence of CAP and its aetiologic agents are needed to improve the diagnosis and treatment of CAP patients.

Epidemiology of macrolide-resistant Mycoplasma pneumoniae by age distribution in Japan

INTRODUCTION

Mycoplasma pneumoniae (M. pneumoniae) is the major pathogen involved in community-acquired pneumonia in all age groups. Resistance to macrolides, the first-line treatment for M. pneumoniae infection, is a major global public health concern. However, studies evaluating macrolide-resistant M. pneumoniae infection simultaneously in all ages are limited. This study aimed to determine the prevalence and clinical characteristics of macrolide-resistant M. pneumoniae infection in terms of age distribution.

METHODS

We enrolled 292 patients in Tokyo, Japan, who visited Eiju General Hospital or Zama Children's Clinic in 2015-2016. Patients were tested using real-time PCR for M. pneumoniae DNA. PCR-positive patients (n = 151) were further selected and sequentially divided into preschool-aged children (≤5 years, n = 31), school-aged children (6-15 years, n = 101), adolescents (16-19 years, n = 5), and adults (≥20 years, n = 14). We then analyzed the M. pneumoniae infection clinical characteristics, prevalence of macrolide-resistant infection, and 23S rRNA domain V resistance-associated mutation status.

RESULTS

We found insignificant differences in the prevalence of macrolide-resistant M. pneumoniae infection among all groups, clinical characteristics, and resistance-associated mutation status in patients with macrolide-resistant M. pneumoniae infection. We also found statistically higher prevalence of mutation-positive (n = 85) M. pneumoniae in patients previously treated with macrolide compared to the mutation-negative group (n = 66); 63.8% vs 11.1% (p < 0.001), respectively.

CONCLUSIONS

We found no significant differences in both clinical characteristics and prevalence of macrolide-resistant M. pneumoniae infection among all ages. Also, previous macrolide treatment contributes to drug-resistance.

Distribution characteristics of serum β2-microglobulin between viral and bacterial lower respiratory tract infections: a retrospective study

Background

Lower respiratory tract infection (LRTI) is one of the leading cause of death in children under 5 years old around the world between 1980 and 2016. Distinguishing between viral and bacterial infection is challenging when children suffered from LRTI in the absence of pathogen detection. The aim of our study is to analyze the difference of serum β2-microglobulin (β2-MG) between viral LRTI and bacterial LRTI in children.

Methods

This retrospective study included children with LRTI caused by a single pathogen from Yancheng Third People’s Hospital, Yancheng, China, between January 1, 2016 and December 31, 2019. Participants were divided into the younger group (1 year old ≤ age < 3 years old) and the older group (3 years old ≤ age < 5 years old) for subgroup analysis.

Results

A total of 475 children with LRTI caused by common respiratory pathogens were identified. In the younger group as well as the older group, the serum level of β2-MG in respiratory syncytial virus, influenza A virus and influenza B virus groups were significantly increased compared to that in the Mycoplasma pneumoniae group. Compared with Streptococcus pneumoniae infection group, the serum β2-MG level of respiratory syncytial virus, influenza A virus and influenza B virus groups were significantly higher in children between 1 and 3 years old.

Conclusions

The serum β2-MG may distinguish viral infection from bacterial infection in children with LRTI.

Differential effects of the Akt pathway on the internalization of Klebsiella by lung epithelium and macrophages

Host response to lung infection includes coordinated efforts of multiple cell types, including the lung epithelium and macrophages. Importantly, both the lung epithelium and macrophages can internalize and clear invading pathogens. However, the mechanisms and their ability to internalize or phagocytose differ. Akt is a key cellular pathway that controls cell proliferation and survival, in addition to its role in host defense. The role of the Akt pathway was assessed using pharmacological Akt modulators in lung epithelial (A549) and macrophage (RAW 264.7) cell lines during Klebsiella bacterial infection. Our data show that the inhibition of the Akt pathway using specific Akt inhibitor MK2206 increased the phagocytic ability of lung epithelial cells but not of macrophages. In contrast, the activation of Akt using specific activator SC-79 decreased the phagocytic ability of epithelial cells, while it increased the phagocytic ability of macrophages. The altered phagocytic ability in both cell types using Akt modulators was not due to changes in bacterial adhesion to the host cell. The clinical usefulness of these Akt modulators may vary based on the type of infection and on the relative contribution of epithelial cells and macrophages in clearing the particular bacterial infection. The Akt pathway has differential roles in the internalization of Klebsiella bacteria by respiratory epithelial cells and immune cells.

Legionella pneumophila sg1-sensing signal enhancement using a novel electrochemical immunosensor in dynamic detection mode

This work presents a comparison between static and dynamic modes of biosensing using a novel microfluidic assay for continuous and quantitative detection of Legionella pneumophila sg1 in artificial water samples. A self-assembled monolayer of 16-amino-1-hexadecanethiol (16-AHT) was covalently linked to a gold substrate, and the resulting modified surface was used to immobilize an anti-Legionella pneumophila monoclonal antibody (mAb). The modified surfaces formed during the biosensor functionalization steps were characterized using electrochemical measurements and microscopic imaging techniques. Under static conditions, the biosensor exhibited a wide linear response range from 10 to 10⁸ CFU/mL and a detection limit of 10 CFU/mL. Using a microfluidic system, the biosensor responses exhibited a linear relationship for low bacterial concentrations ranging from 10 to 10³ CFU/mL under dynamic conditions and an enhancement of sensing signals by a factor of 4.5 compared to the sensing signals obtained under static conditions with the same biosensor for the detection of Legionella cells in artificially contaminated samples.

Pharmacotherapy of Lower Respiratory Tract Infections in Elderly-Focused on Antibiotics

Lower respiratory tract infections (LRTIs) refer to the inflammation of the trachea, bronchi, bronchioles, and lung tissue. Old people have an increased risk of developing LRTIs compared to young adults. The prevalence of LRTIs in the elderly population is not only related to underlying diseases and aging itself, but also to a variety of clinical issues, such as history of hospitalization, previous antibacterial therapy, mechanical ventilation, antibiotic resistance. These factors mentioned above have led to an increase in the prevalence and mortality of LRTIs in the elderly, and new medical strategies targeting LRTIs in this population are urgently needed. After a systematic review of the current randomized controlled trials and related studies, we recommend novel pharmacotherapies that demonstrate advantages for the management of LRTIs in people over the age of 65. We also briefly reviewed current medications for respiratory communicable diseases in the elderly. Various sources of information were used to ensure all relevant studies were included. We searched Pubmed, MEDLINE (OvidSP), EMBASE (OvidSP), and ClinicalTrials.gov. Strengths and limitations of these drugs were evaluated based on whether they have novelty of mechanism, favorable pharmacokinetic/pharmacodynamic profiles, avoidance of interactions and intolerance, simplicity of dosing, and their ability to cope with challenges which was mainly evaluated by the primary and secondary endpoints. The purpose of this review is to recommend the most promising antibiotics for treatment of LRTIs in the elderly (both in hospital and in the outpatient setting) based on the existing results of clinical studies with the novel antibiotics, and to briefly review current medications for respiratory communicable diseases in the elderly, aiming to a better management of LRTIs in clinical practice.

Pneumococcal lineages associated with serotype replacement and antibiotic resistance in childhood invasive pneumococcal disease in the post-PCV13 era: an international whole-genome sequencing study

BACKGROUND

Invasive pneumococcal disease remains an important health priority owing to increasing disease incidence caused by pneumococci expressing non-vaccine serotypes. We previously defined 621 Global Pneumococcal Sequence Clusters (GPSCs) by analysing 20 027 pneumococcal isolates collected worldwide and from previously published genomic data. In this study, we aimed to investigate the pneumococcal lineages behind the predominant serotypes, the mechanism of serotype replacement in disease, as well as the major pneumococcal lineages contributing to invasive pneumococcal disease in the post-vaccine era and their antibiotic resistant traits.

METHODS

We whole-genome sequenced 3233 invasive pneumococcal disease isolates from laboratory-based surveillance programmes in Hong Kong (n=78), Israel (n=701), Malawi (n=226), South Africa (n=1351), The Gambia (n=203), and the USA (n=674). The genomes represented pneumococci from before and after pneumococcal conjugate vaccine (PCV) introductions and were from children younger than 3 years. We identified predominant serotypes by prevalence and their major contributing lineages in each country, and assessed any serotype replacement by comparing the incidence rate between the pre-PCV and PCV periods for Israel, South Africa, and the USA. We defined the status of a lineage as vaccine-type GPSC (≥50% 13-valent PCV [PCV13] serotypes) or non-vaccine-type GPSC (>50% non-PCV13 serotypes) on the basis of its initial serotype composition detected in the earliest vaccine period to measure their individual contribution toward serotype replacement in each country. Major pneumococcal lineages in the PCV period were identified by pooled incidence rate using a random effects model.

FINDINGS

The five most prevalent serotypes in the PCV13 period varied between countries, with only serotypes 5, 12F, 15B/C, 19A, 33F, and 35B/D common to two or more countries. The five most prevalent serotypes in the PCV13 period varied between countries, with only serotypes 5, 12F, 15B/C, 19A, 33F, and 35B/D common to two or more countries. These serotypes were associated with more than one lineage, except for serotype 5 (GPSC8). Serotype replacement was mainly mediated by expansion of non-vaccine serotypes within vaccine-type GPSCs and, to a lesser extent, by increases in non-vaccine-type GPSCs. A globally spreading lineage, GPSC3, expressing invasive serotypes 8 in South Africa and 33F in the USA and Israel, was the most common lineage causing non-vaccine serotype invasive pneumococcal disease in the PCV13 period. We observed that same prevalent non-vaccine serotypes could be associated with distinctive lineages in different countries, which exhibited dissimilar antibiotic resistance profiles. In non-vaccine serotype isolates, we detected significant increases in the prevalence of resistance to penicillin (52 [21%] of 249 vs 169 [29%] of 575, p=0·0016) and erythromycin (three [1%] of 249 vs 65 [11%] of 575, p=0·0031) in the PCV13 period compared with the pre-PCV period.

INTERPRETATION

Globally spreading lineages expressing invasive serotypes have an important role in serotype replacement, and emerging non-vaccine serotypes associated with different pneumococcal lineages in different countries might be explained by local antibiotic-selective pressures. Continued genomic surveillance of the dynamics of the pneumococcal population with increased geographical representation in the post-vaccine period will generate further knowledge for optimising future vaccine design.

FUNDING

Bill & Melinda Gates Foundation, Wellcome Sanger Institute, and the US Centers for Disease Control.

Spectrum of imaging findings in pulmonary infections. Part 1: Bacterial and viral

Chest radiography is generally the first imaging modality used for the evaluation of pneumonia. It can establish the presence of pneumonia, determine its extent and location, and assess the response to treatment. Computed tomography is not used for the initial evaluation of pneumonia, but it may be used when the response to treatment is unusually slow. It helps to identify complications, detect any underlying chronic pulmonary disease, and also to characterise complex pneumonias. Although not diagnostic, certain imaging findings may suggest a particular microbial cause over others. Knowledge of whether pneumonia is community-acquired or nosocomial, as well as the age and immune status of the patient, can help us in narrowing the differential diagnoses. The purpose of this article is to briefly review the various pulmonary imaging manifestations of pathogenic organisms. This knowledge along with clinical history and laboratory investigations of the patient may help in guiding the treatment of pneumonia.

Pneumonia

By nearly any criteria, pneumonia (infection of the pulmonary parenchyma) must be considered one of the most important categories of disease affecting the respiratory system. This chapter is organized primarily as a general discussion of the clinical problem of pneumonia. As appropriate, the focus on individual etiologic agents highlights some characteristic features of each that are particularly useful to the physician. Also covered is a commonly used categorization of pneumonia based on the clinical setting: community-acquired versus nosocomial (hospital-acquired) pneumonia. In current clinical practice, the approach to evaluation and management of these two types of pneumonia is often quite different. The chapter concludes with a brief discussion of several infections that were uncommon or primarily of historical interest until recently, as the threat of bioterrorism emerged. In addition to reviewing inhalational anthrax, the chapter briefly describes two other organisms considered to be of concern as potential weapons of bioterrorism: Yersinia pestis (the cause of plague) and Francisella tularensis (the cause of tularemia).

Neumonías bacterianas no neumocócicas (II). Infecciones respiratorias por Mycoplasma y Chlamydia. Neumonías víricas

Las neumonías no neumocócicas y víricas se incluyen en el grupo denominado neumonías atípicas. Son causadas por un amplio grupo de bacterias y virus, no obteniéndose en la mayoría de los casos el diagnóstico etiológico. Con frecuencia su presentación suele ser leve, aunque se han descrito casos fatales, principalmente en pacientes inmunocomprometidos. En ocasiones asocian clínica extrapulmonar dificultando su diagnóstico. Las pruebas microbiológicas no están indicadas en su diagnóstico, salvo en los casos de fracaso terapéutico o ante la necesidad de hospitalización del paciente. El tratamiento antibiótico empírico precoz debe iniciarse lo antes posible, puesto que esta medida ha demostrado disminuir la morbimortalidad. Las modificaciones en el mismo o la indicación de tratamiento antivírico asociado solo se realizan según la evolución clínica o la gravedad de la presentación. Otros tratamientos como la corticoterapia continúan siendo controvertidos.

[Clinical effect of Saccharomyces boulardii powder combined with azithromycin sequential therapy in treatment of children with diarrhea secondary to Mycoplasma pneumoniae pneumonia]

OBJECTIVE

To investigate the clinical effect of Saccharomyces boulardii powder combined with azithromycin sequential therapy in the treatment of children with diarrhea secondary to Mycoplasma pneumoniae pneumonia.

METHODS

A total of 88 children with diarrhea secondary to Mycoplasma pneumoniae pneumonia between June 2015 and March 2017 were divided into control group and study group using a random number table, with 44 children in each group. The children in the control group were given routine treatment combined with azithromycin sequential therapy, and those in the study group were given oral Saccharomyces boulardii powder in addition to the treatment in the control group until the end of azithromycin sequential therapy. After the treatment ended, the two groups were compared in terms of time to improvement of clinical symptoms, length of hospital stay, clinical outcome, defecation frequency before and after treatment, condition of intestinal dysbacteriosis, and incidence of adverse events.

RESULTS

Compared with the control group, the study group had significantly shorter time to improvement of clinical symptoms and length of hospital stay (P<0.05). The study group had a significantly higher response rate than the control group (P<0.05). On days 3 and 5 of treatment, the study group had a significant reduction in defecation frequency compared with the control group (P<0.05). The study group had a significantly lower rate of intestinal dysbacteriosis than the control group (P<0.05). There was no significant difference in the incidence of adverse events between the two groups (P>0.05).

CONCLUSIONS

In the treatment of children with diarrhea secondary to Mycoplasma pneumoniae pneumonia, Saccharomyces boulardii powder combined with azithromycin sequential therapy can improve clinical symptoms, shorten the length of hospital stay, reduce defecation frequency and the incidence of intestinal dysbacteriosis, and improve clinical outcomes, and does not increase the risk of adverse events.

Detection of respiratory bacterial pathogens causing atypical pneumonia by multiplex Lightmix® RT-PCR

Pneumonia is a severe infectious disease. In addition to common viruses and bacterial pathogens (e.g. Streptococcus pneumoniae), fastidious respiratory pathogens like Chlamydia pneumoniae, Mycoplasma pneumoniae and Legionella spp. can cause severe atypical pneumonia. They do not respond to penicillin derivatives, which may cause failure of antibiotic empirical therapy. The same applies for infections with B. pertussis and B. parapertussis, the cause of pertussis disease, that may present atypically and need to be treated with macrolides. Moreover, these fastidious bacteria are difficult to identify by culture or serology, and therefore often remain undetected. Thus, rapid and accurate identification of bacterial pathogens causing atypical pneumonia is crucial. We performed a retrospective method evaluation study to evaluate the diagnostic performance of the new, commercially available Lightmix^® multiplex RT-PCR assay that detects these fastidious bacterial pathogens causing atypical pneumonia. In this retrospective study, 368 clinical respiratory specimens, obtained from patients suffering from atypical pneumonia that have been tested negative for the presence of common agents of pneumonia by culture and viral PCR, were investigated. These clinical specimens have been previously characterized by singleplex RT-PCR assays in our diagnostic laboratory and were used to evaluate the diagnostic performance of the respiratory multiplex Lightmix^® RT-PCR. The multiplex RT-PCR displayed a limit of detection between 5 and 10 DNA copies for different in-panel organisms and showed identical performance characteristics with respect to specificity and sensitivity as in-house singleplex RT-PCRs for pathogen detection. The Lightmix^® multiplex RT-PCR assay represents a low-cost, time-saving and accurate diagnostic tool with high throughput potential. The time-to-result using an automated DNA extraction device for respiratory specimens followed by multiplex RT-PCR detection was below 4 h, which is expected to significantly improve diagnostics for atypical pneumonia-associated bacterial pathogens.