Prevalence of atypical pathogens in patients with severe pneumonia: a systematic review and meta-analysis

Severe Pneumonia

Severe pneumonia is a leading cause of mortality and morbidity worldwide. Being a complex condition caused by a variety of microorganisms including bacteria, viruses, and fungi, it requires intensive care. A combination of early initiation of antimicrobial therapy and adjunctive nonantimicrobial interventions improve patient outcomes. This article reviews the most recent data on the epidemiology, microbiology, diagnosis, and management of severe pneumonia.

Rapid detection of Mycoplasma pneumoniae CARDS toxin in clinical respiratory specimens by a loop-mediated isothermal amplification assay

In light of the absence of rapid and precise diagnostic laboratory tests for the detection of Mycoplasma pneumoniae (MP), a prominent etiological agent implicated in a range of respiratory infections, we developed and evaluated a rapid and straightforward loop-mediated isothermal amplification (LAMP) assay targeting the MP community-acquired respiratory distress syndrome toxin (CARDS TX) gene. The LAMP assay was performed at 65°C for a duration of 60 min, yielding a minimum detection concentration of MP CARDS TX at 0.4986 pg/μl. The assay exhibited no cross-reactivity with 13 other prevalent pathogens associated with respiratory infections or with other common bacterial toxin genes. To further substantiate the validity of the LAMP assay, 200 pharyngeal swabs or bronchoalveolar lavage (BAL) samples were collected from inpatients diagnosed with community-acquired pneumonia (CAP) between June 2021 and July 2022. The results were compared with those obtained by the quantitative real-time polymerase chain reaction (qPCR) method for verification purposes. Of the 200 clinical specimens, 11 exhibited positive results for MP by LAMP and 10 displayed positive results for MP by qPCR (P = 1.000). In summary, a sensitive, specific, straightforward, and expeditious LAMP method for CARDS TX identification was developed to facilitate rapid detection of MP in point-of-care settings. This assay enables early and accurate diagnosis, even in resource-limited environments, which is important for proper antibiotic treatment and prognosis of MP infection.

Successful Outpatient Treatment of Legionella pneumophila Pneumonia With Lascufloxacin: A Case Report

Legionella pneumophila is a significant cause of community-acquired pneumonia (CAP) and often necessitates hospitalization. Lascufloxacin (LSFX), a novel fluoroquinolone with high pulmonary penetration, has demonstrated efficacy in treating Legionella pneumonia in hospitalized patients. However, its use in an outpatient setting for Legionella pneumonia has not been previously documented, despite its favorable pharmacokinetics and safety profile. We present a 49-year-old man with a history of smoking and dyslipidemia who developed a high fever, headache, and malaise. In addition to the presence of relative bradycardia, chest imaging revealed right lower lobe pneumonia, and a urinary antigen test confirmed Legionella pneumophila infection. Despite this diagnosis, his condition remained stable (A-DROP score: 1), allowing for outpatient management. He was prescribed LSFX 75 mg/day for 10 days, with close monitoring via home pulse oximetry and scheduled frequent follow-up visits. His fever was resolved by day 3, and he fully recovered without complications or adverse effects. This is the first reported case of successful outpatient treatment of Legionella pneumonia with LSFX. The decision for outpatient therapy was based on the patient's stable condition based on A-DROP (age, dehydration, respiratory failure, orientation disturbance, and low blood pressure) scoring, LSFX's excellent bioavailability and pulmonary penetration, and its lack of renal dose adjustment requirements. However, the A-DROP scoring system may underestimate Legionella pneumonia severity, necessitating careful patient selection. LSFX appears to be a safe and effective option for outpatient management of mild Legionella pneumonia. This case highlights its potential as an alternative to inpatient treatment, but further studies are required to confirm its broader applicability.

Effectiveness of macrolides as add-on therapy to beta-lactams in community-acquired pneumonia: A meta-analysis of randomized controlled trials

PURPOSE

This study aims to evaluate whether adding macrolides (MAC) to beta-lactam (BL) monotherapy in the treatment of community-acquired pneumonia (CAP) offers clinical benefits that justify the potential disadvantages or side effects.

METHODS

We systematically searched PubMed, Embase, and Cochrane for randomized controlled trials (RCTs) comparing BL monotherapy to combination therapy with BL and MAC for the in-hospital treatment of CAP. We pooled mean differences (MD) for continuous outcomes and risk ratio (RR) for binary outcomes, with 95% confidence intervals (CI).

RESULTS

Six RCTs with 2661 participants (52% receiving combination therapy), revealed no significant difference in in-hospital mortality (RR 0.99; 95% CI 0.78 to 1.25; p = 0.94; I2 = 0%), 90-day mortality (RR 1.03; 95% CI 0.82 to 1.29; p = 0.83; I2 = 13%), or 30-day mortality (RR 0.90; 75% CI 0.63 to 1.29; p = 0.58; I2 = 54%). Additionally, no significant differences were observed in the length of hospital stay (MD 0.51; 95% CI - 0.50 to 1.51; p = 0.33; I2 = 63%) or respiratory insufficiency (RR 0.63; 95% CI 0.29 to 1.35; p = 0.24; I2 = 74%). However, combination therapy significantly improved the treatment success rate (RR 1.17; 95% CI 1.04 to 1.32; p = 0.009; I2 = 0%).

CONCLUSION

Our findings suggest that BL + MAC therapy should not be used in all cases of hospitalized patients with CAP.

PROSPERO ID

CRD42024516383 - Data of registration: 03/03/2024.

Atypical pneumonia (Review)

Atypical pneumonia encompasses diverse pathogens, such as Chlamydia pneumoniae, Mycoplasma pneumoniae and Legionella species, which differ from typical bacterial pneumonia in their extrapulmonary manifestations. Clinical differentiation relies on systemic involvement rather than on standalone symptoms. Despite challenges in distinct diagnosis, syndromic approaches and weighted point systems aid in accurate presumptive diagnoses. Antibiotic treatment, often non-β-lactams due to the unique cell structures of atypical pathogens, targets intracellular processes. Macrolides, tetracyclines, quinolones and ketolides are effective due to their intracellular penetration, crucial for combating these intracellular pathogens. The prevalence of atypical pneumonia varies globally, with Europe, Asia/Africa and Latin America reporting detection rates between 20-28%. Streptococcus pneumoniae remains a primary cause of pneumonia; however, atypical pathogens contribute significantly to this disease, being more prevalent in outpatient settings and among young adults. Legionella stands out in severe hospitalized cases and is associated with higher mortality rates. Diagnosis proves challenging due to overlapping symptoms with other respiratory infections. Differentiation among pathogens, such as Chlamydia pneumoniae, Mycoplasma pneumoniae and Legionella relies on subtle clinical variations and imaging findings. Diagnostic methods include serological studies, cultures and polymerase chain reaction, each with limitations in sensitivity or specificity. Prognosis varies widely. Atypical pneumonia can progress to severe forms with fatal outcomes, causing multi-organ damage. Complications extend beyond the respiratory system, affecting the cardiovascular system, exacerbating conditions such as chronic obstructive pulmonary disease and asthma, and potentially linking to conditions such as lung cancer. Increasing antibiotic resistance poses a significant challenge, influencing treatment outcomes and prolonging illness duration.

Chlamydia in pigs: intriguing bacteria associated with sub-clinical carriage and clinical disease, and with zoonotic potential

Chlamydiae are bacteria that are intriguing and important at the same time. The genus Chlamydia encompasses many species of obligate intracellular organisms: they can multiply only inside the cells of their host organism. Many, perhaps most animals have their own specifically adapted chlamydial species. In humans, the clinically most relevant species is Chlamydia trachomatis, which has particular importance as an agent of sexually transmitted disease. Pigs are the natural host of Chlamydia suis but may also carry Chlamydia abortus and Chlamydia pecorum. C. abortus and possibly C. suis have anthropozoonotic potential, which makes them interesting to human medicine, but all three species bring a substantial burden of disease to pigs. The recent availability of genomic sequence comparisons suggests adaptation of chlamydial species to their respective hosts. In cell biological terms, many aspects of all the species seem similar but non-identical: the bacteria mostly replicate within epithelial cells; they are taken up by the host cell in an endosome that they customize to generate a cytosolic vacuole; they have to evade cellular defences and have to organize nutrient transport to the vacuole; finally, they have to organize their release to be able to infect the next cell or the next host. What appears to be very difficult and challenging to achieve, is in fact a greatly successful style of parasitism. I will here attempt to cover some of the aspects of the infection biology of Chlamydia, from cell biology to immune defence, epidemiology and possibilities of prevention. I will discuss the pig as a host species and the species known to infect pigs but will in particular draw on the more detailed knowledge that we have on species that infect especially humans.

Microbiology of Severe Community-Acquired Pneumonia and the Role of Rapid Molecular Techniques

The microbiology of severe community acquired pneumonia (SCAP) has implications on management, clinical outcomes and public health policy. Therefore, knowledge of the etiologies of SCAP and methods to identify these microorganisms is key. Bacteria including Streptococcus pneumoniae, Staphylococcus aureus and Enterobacteriaceae continue to be important causes of SCAP. Viruses remain the most commonly identified etiology of SCAP. Atypical organisms are also important etiologies of SCAP and are critical to identify for public health. With the increased number of immunocompromised individuals, less common pathogens may also be found as the causative agent of SCAP. Traditional diagnostic tests, including semi-quantitative respiratory cultures, blood cultures and urinary antigens continue to hold an important role in the evaluation of patients with SCAP. Many of the limitations of the aforementioned tests are addressed by rapid, molecular diagnostic tests. Molecular diagnostics utilize culture-independent technology to identify species-specific genetic sequences. These tests are often semi-automated and provide results within hours, which provides an opportunity for expedient antibiotic stewardship. The existing literature suggests molecular diagnostic techniques may improve antibiotic stewardship in CAP, and future research should investigate optimal methods for implementation of these assays into clinical practice.