Clinical characteristics of community-acquired pneumonia due to Moraxella catarrhalis in adults: a retrospective single-centre study

Bacterial antigens and asthma: a comparative study of common respiratory pathogenic bacteria

Objective: In a previous study we have shown that, in the presence of interleukin (IL)-33, repeated, per-nasal challenge of murine airways with Streptococcus pneumoniae (S. pneumoniae) organisms induces human asthma-like airways inflammation. It is not clear, however, whether this effect is unique or manifest in response to other common respiratory pathogens.Methods: To explore this, airways of BALB/c mice were repeatedly challenged per-nasally with formaldehyde-inactivated bacterial bodies in the presence or absence of murine recombinant IL-33. Serum concentrations of S.pneumoniae, Moraxella catarrhalis (M.catarrhalis) and Haemophilus influenzae (H.influenzae) lysates-specific IgE were measured in patients with asthma and control subjects.Results: We showed that in the presence of IL-33, repeated, per-nasal airways exposure to the bodies of these bacteria induced airways hyperresponsiveness (AHR) in the experimental mice. This was accompanied by cellular infiltration into bronchoalveolar lavage fluid (BALF), eosinophilic infiltration and mucous hypertrophy of the lung tissue, with elevated local expression of some type 2 cytokines and elevated, specific IgG and IgE in the serum. The precise characteristics of the inflammation evoked by exposure to each bacterial species were distinguishable.Conclusions: These results suggest that in the certain circumstances, inhaled or commensal bacterial body antigens of both Gram-positive (S. pneumoniae) and Gram-negative (M. catarrhalis and H. influenzae) respiratory tract bacteria may initiate type 2 inflammation typical of asthma in the airways. In addition, we demonstrated that human asthmatic patients manifest elevated serum concentrations of M.catarrhalis- and H.influenzae-specific IgE.

7-Year (2015-21) longitudinal surveillance of lefamulin in vitro activity against bacterial pathogens collected worldwide from patients with respiratory tract infections including pneumonia and characterization of resistance mechanisms

OBJECTIVES

Lefamulin (Xenleta™), a pleuromutilin antibiotic, was approved for the oral and IV treatment of community-acquired bacterial pneumonia (CABP) in adults in 2019/2020. This study evaluated the in vitro activity of lefamulin and comparators against 19 584 unique bacterial isolates collected from patients with community-acquired respiratory tract infections and hospitalized patients with pneumonia within the global SENTRY Antimicrobial Surveillance Program during 2015-21.

METHODS

Isolates were susceptibility tested by the CLSI broth microdilution method, and resistance mechanisms were investigated in isolates with elevated lefamulin MICs.

RESULTS

Lefamulin exhibited potent antibacterial activity against the most common and typical CABP pathogens tested, including Streptococcus pneumoniae [MIC50/90, 0.06/0.25 mg/L; 99.9% susceptible (S)], Staphylococcus aureus (MIC50/90, 0.06/0.12 mg/L; 99.6% S), Haemophilus influenzae (MIC50/90, 0.5/2 mg/L; 99.1% S) and Moraxella catarrhalis (MIC50/90, 0.06/0.12 mg/L; 100.0% S). Potent activity was also observed against the less common pneumonia pathogens: β-haemolytic (MIC50/90 of 0.03/0.06 mg/L) and viridans group Streptococcus spp. (MIC50/90 of 0.06/0.25 mg/L) and Haemophilus parainfluenzae (MIC50/90 of 1/4 mg/L). Lefamulin's activity was not adversely affected by resistance to macrolides, penicillin, tetracyclines, fluoroquinolones and other resistance phenotypes. Non-susceptibility/resistance to lefamulin was rare and primarily determined by ribosomal protection through vga(A) variants in S. aureus, overexpression of AcrAB-TolC efflux pump in H. influenzae or modifications in L3, L4 and 23SrRNA in Streptococcus spp.

CONCLUSIONS

Based on the coverage of the most important CABP pathogens and lacking cross-resistance, lefamulin may represent a valuable empirical treatment option for ambulatory and hospitalized patients with CABP, particularly in settings with high prevalence of resistance.

Diagnostic utility of oropharyngeal swabs as an alternative to lower respiratory tract samples for PCR-based syndromic testing in patients with community-acquired pneumonia

Syndromic PCR-based analysis of lower respiratory tract (LRT) samples in patients with community-acquired pneumonia (CAP) improves the bacterial yield and time-to-results compared to culture-based methods. However, obtaining adequate sputum samples can be challenging and is frequently not prioritized in the emergency department (ED). In this study, we assess the concordance of microbiological detections between oropharyngeal- (OP) and LRT samples from patients presenting to the ED with CAP using a syndromic PCR-based respiratory panel [Biofire FilmArray Pneumonia plus (FAP plus)]. Paired OP- and high-quality LRT samples were collected from 103 patients with confirmed CAP, who had been included in a randomized controlled trial (NCT04660084) or a subsequent observational study at Haukeland University Hospital, and analyzed using the FAP plus. The LRT samples were obtained mainly by sputum induction (88%). Using the LRT samples as a reference standard, the positive percent agreement (PPA), negative percent agreement (NPA), and overall percent agreement for the most common bacterial pathogens in CAP, Streptococcus pneumoniae and Haemophilus influenzae, were 85%, 99% and 95%, and 86%, 98% and 93%, respectively. For Moraxella catarrhalis, the PPA was lower (74%), while the NPA was 100%. For bacteria that are less likely causes of uncomplicated CAP (e.g., Staphylococcus aureus and Enterobacterales) the results were more divergent. In conclusion, the FAP plus detects the most common CAP pathogens S. pneumoniae and H. influenzae from OP samples with high PPAs and excellent NPAs when compared with LRT samples. For these pathogens, the PPAs for OP samples were higher than previous reports for nasopharyngeal samples. This suggests that analysis of OP samples with syndromic PCR panels could represent an alternative approach for rapid microbiological testing in the ED, especially in patients where LRT samples are difficult to obtain. Divergent results for bacteria that are less likely to cause uncomplicated CAP do, however, emphasize the need for clinical evaluation of positive test results.

Antimicrobial Resistance Trends of the Most Common Causative Pathogens Associated with Community-acquired Respiratory Infections in China: 2009–2018

Background

Emergence of antimicrobial resistance poses new challenges in the management of community acquired respiratory tract infections (CARTIs). Therefore, surveillance on the antimicrobial susceptibilities of common respiratory pathogens is valuable and guides empirical therapeutic choices in management of CARTIs.

Objective

The objective of the current study is to summarize the antimicrobial resistance trends in common respiratory tract pathogens isolated from patients with CARTIs in China, over a 10-year period (2009–2018).

Methods

Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis strains were collected from multicenter, and antimicrobial susceptibility testing was performed in the research central laboratory of each study period from 2009–2018. The pathogens that accounted for CARTIs in the adult population was considered and summarized.

Results

From 2009–2018 a total of 3750 isolates were collected from 22 cities located across different regions of China. Among these the most common bacterial isolates include S. pneumoniae (53.7%) followed by H. influenza (32.4%), M. catarrhalis (13.9%). S. pneumoniae exhibited reduction in susceptibility and increase in resistance to penicillin, cephalosporins (cefaclor, cefuroxime, ceftriaxone) during the surveillance period. Invasive and noninvasive S. pneumoniae showed similar resistance. In the case of H. influenzae susceptibility to β-lactam and β-lactamase inhibitors (ampicillin, amoxicillin and AMC), SXT, clarithromycin and cephalosporins (cefuroxime, cefaclor, ceftazidime) was reduced over the past 10 years with an exception of ceftriaxone. Overall, moxifloxacin and levofloxacin have the highest susceptibility rates against S. pneumoniae (>95%) and H. influenza (>90%). M. catarrhalis exhibited susceptibility to almost all the tested antimicrobials.

Conclusion

In China the 10-year trends showed a substantial increase in resistance to β-lactam drugs and reduction in sensitivity. However, certain antimicrobial agents namely fluoroquinolones including moxifloxacin and levofloxacin maintained low resistance rates with better susceptibility. Further, with few exceptions decline in susceptibility rates to macrolides and cephalosporins was observed among the tested pathogens.

Correlation of Moraxella catarrhalis macrolide susceptibility with the ability to adhere and invade human respiratory epithelial cells

Recently, the prevalence of macrolide-resistant Moraxella catarrhalis has been reported, especially among Chinese children. The fitness cost of resistance is reported to render the resistant bacteria less virulent. To investigate the correlation between macrolide susceptibility of M. catarrhalis and pathogenicity, the whole genome of 70 M. catarrhalis isolates belonging to four clonal complexes with different macrolide susceptibilities was sequenced. The gene products were annotated with the Gene Ontology terms. Based on 46 extracted essential virulence genes, 19 representative isolates were selected to infect type II alveolar cells (A549 cells). The ability of these isolates to adhere and invade human epithelial cells and to produce cytokines was comparatively analysed. Furthermore, mice were infected with a pair of M. catarrhalis isolates with different pathogenic behaviours and macrolide susceptibilities to examine pulmonary clearance, histological findings, and the production of cytokines. The percentages of annotations for binding, metabolic process, cellular process, and cell were non-significantly different between the macrolide-resistant and macrolide-susceptible groups. The presence of uspA2, uspA2H, pilO, lbpB, lex1, modM, mboIA, and mboIB significantly differed among the four clonal complexes and macrolide susceptibility groups. Furthermore, compared with those in macrolide-susceptible isolates, the adhesion ability was stronger (P = 0.0019) and the invasion ability was weaker (P < 0.0001) in the macrolide-resistant isolates. Mouse experiments revealed that pulmonary macrophages elicit immune responses against M. catarrhalis infection by significantly upregulating the Csf2, Il4, Il13, Il1b, Il6, Tnf, and Il18. Therefore, M. catarrhalis populations exhibited diverse pathogenicity in vitro and in vivo.

Confounding Effect of Undergraduate Semester-Driven "Academic" Internet Searches on the Ability to Detect True Disease Seasonality in Google Trends Data: Fourier Filter Method Development and Demonstration

Background

Internet search volume for medical information, as tracked by Google Trends, has been used to demonstrate unexpected seasonality in the symptom burden of a variety of medical conditions. However, when more technical medical language is used (eg, diagnoses), we believe that this technique is confounded by the cyclic, school year-driven internet search patterns of health care students.

Objective

This study aimed to (1) demonstrate that artificial "academic cycling" of Google Trends' search volume is present in many health care terms, (2) demonstrate how signal processing techniques can be used to filter academic cycling out of Google Trends data, and (3) apply this filtering technique to some clinically relevant examples.

Methods

We obtained the Google Trends search volume data for a variety of academic terms demonstrating strong academic cycling and used a Fourier analysis technique to (1) identify the frequency domain fingerprint of this modulating pattern in one particularly strong example, and (2) filter that pattern out of the original data. After this illustrative example, we then applied the same filtering technique to internet searches for information on 3 medical conditions believed to have true seasonal modulation (myocardial infarction, hypertension, and depression), and all bacterial genus terms within a common medical microbiology textbook.

Results

Academic cycling explains much of the seasonal variation in internet search volume for many technically oriented search terms, including the bacterial genus term ["Staphylococcus"], for which academic cycling explained 73.8% of the variability in search volume (using the squared Spearman rank correlation coefficient, P<.001). Of the 56 bacterial genus terms examined, 6 displayed sufficiently strong seasonality to warrant further examination post filtering. This included (1) ["Aeromonas" + "Plesiomonas"] (nosocomial infections that were searched for more frequently during the summer), (2) ["Ehrlichia"] (a tick-borne pathogen that was searched for more frequently during late spring), (3) ["Moraxella"] and ["Haemophilus"] (respiratory infections that were searched for more frequently during late winter), (4) ["Legionella"] (searched for more frequently during midsummer), and (5) ["Vibrio"] (which spiked for 2 months during midsummer). The terms ["myocardial infarction"] and ["hypertension"] lacked any obvious seasonal cycling after filtering, whereas ["depression"] maintained an annual cycling pattern.

Conclusions

Although it is reasonable to search for seasonal modulation of medical conditions using Google Trends' internet search volume and lay-appropriate search terms, the variation in more technical search terms may be driven by health care students whose search frequency varies with the academic school year. When this is the case, using Fourier analysis to filter out academic cycling is a potential means to establish whether additional seasonality is present.

Isolation and characterisation of antibacterial and anti-inflammatory compounds from Gnaphalium polycaulon

ETHNO-PHARMACOLOGICAL RELEVANCE

Gnaphalium polycaulon commonly known as "cudweed" has been used throughout South America as an infusion to treat colds, bronchitis, fever or pneumonia.

AIM OF THE STUDY

This study aimed to determine the antibacterial and anti-inflammatory activities of the aqueous extract of Gnaphalium polycaulon and identify the related compounds.

MATERIALS AND METHODS

A bio-guided isolation of the active compounds of Gnaphalium polycaulon was carried out, selecting the fractions depending on their antibacterial, anti-inflammatory and cytotoxic activities. The antibacterial effect was studied against Haemophilus influenzae, Moraxella catarrhalis, Staphylococcus aureus and Streptococcus pneumoniae; and the anti-inflammatory study was performed by measuring the inhibition of NF-κB in BEAS-2B and IMR-90 cell cultures.

RESULTS

Three compounds were obtained and characterised by nuclear magnetic resonance and mass spectrometry. These compounds are 2-(4-(1-H-tetrazol-1-yl) phenyl)-2-aminopropanoic acid (1), N-phenyl-4-(3-phenyl-1,2,4-thiadiazol-5-yl) piperazine-1-carboxamide (2) and N-(4-ethoxyphenyl)-4-(2-methylimidazo-[1,2-α] pyridine-3-yl) thiazol-2-amine (3). All compounds showed antibacterial activity with MIC values of 44.80-44.85, 0.017-0.021 and 0.0077-0.0079 μM, respectively, in the Haemophilus influenzae, Moraxella catarrhalis, Staphylococcus aureus and Streptococcus pneumoniae strains, while the positive control, Ofloxacin, had a MIC value of 27.64-27.67 μM. This was corroborated through a zone inhibition assay, where compound 3 (11.36-11.67 mm) was much more active than the positive control (Ofloxacin, 23.41-24.12 mm), while compounds 2 (26.47-27.64 mm) and 1 (28.39-29.76 mm) displayed similar antibacterial potential to the positive control. Finally, all the compounds presented NF-κB inhibitory activity, compounds 3 (IC₅₀ = 0.0071-0.0073 μM) and 2 (IC₅₀ = 0.016-0.019 μM) being the most promising. Compound 1 (IC₅₀ = 44.24-44.26 μM) had less anti-inflammatory potential, being also the closest to the values displayed by the positive control (Celastrol, IC₅₀ = 7.41 μM).

CONCLUSION

In the present study, three compounds were isolated for the first time from the aqueous extract of Gnaphalium polycaulon. Their antibacterial and anti-inflammatory potential was tested and showcased.

Delafloxacin for the treatment of adult patients with community-acquired bacterial pneumonia

INTRODUCTION

Delafloxacin is a novel fluoroquinolone with peculiar characteristics such as a weak acid character, frequent in vitro activity against methicillin-resistant Staphylococcus aureus (MRSA), and a low potential for resistance selection compared with other fluoroquinolones.

AREAS COVERED

The present narrative review summarizes the available data on the use of delafloxacin for the treatment of community-acquired bacterial pneumonia (CABP).

EXPERT OPINION

Delafloxacin is a novel fluoroquinolone with a unique profile and some interesting characteristics for the treatment of CABP, such as its marked activity against gram-positive bacteria, including MRSA, the possible use as monotherapy (owing to anti-Gram-negative and anti-atypical bacteria activity), the retained activity against many Gram-positive organisms resistant to other fluoroquinolones, and the availability of both oral and intravenous formulations. The results of the DEFINE-CABP phase-3 randomized controlled trial have shown noninferiority of delafloxacin vs. moxifloxacin for the treatment of CABP, thereby providing a further option for this indication. Against this background, future post-marketing experiences remain of crucial importance for further refining the place in therapy of delafloxacin in the real-life management algorithms of CABP, either as first-line option or step-down/outpatient treatment.

Clinical characteristics and outcomes of community-acquired pneumonia in western Saudi Arabia: A four-year retrospective analysis of medical records

BACKGROUND

Community-acquired pneumonia (CAP) is a significant cause of morbidity and mortality, especially for the elderly and people who suffer from chronic conditions. This study was conducted to assess the clinical and microbiological characteristics and disease outcomes associated with the occurrence of CAP.

METHODS

This retrospective chart review was conducted at King Abdulaziz Medical City, Jeddah, Saudi Arabia. Cases with documented clinical diagnosis of CAP during the period from 2016 to 2019 were included. Data were collected on demographic, clinical, and microbiological characteristics, used antimicrobials and patients' outcomes, including length of hospital stay, intensive care unit admission, and mortality. Multivariate regression analysis was performed to identify risk factors for increased length of hospital stay.

RESULTS

A total of two hundred and eighteen CAP episodes were identified. Patients had a median age of 64.5 years, and 54.1% were males. Microbiological diagnosis was established in 33 patients (15.1%). Admission to ICU and diagnosis of a neurological disease were significantly associated with longer hospital stay (>7 days). An average of 2.7 antimicrobials were used per patient, and the most common antibiotics used were Piperacillin/Tazobactam (46.3%), Doxycycline (44%), then Ceftriaxone (42.7%). Four patients (1.8%) died during hospital stay.

CONCLUSIONS

This retrospective analysis of CAP cases identified a lack of microbiological diagnosis and increased burden associated with disease severity and the need for hospitalization. The ability to identify CAP at an earlier stage will be a cornerstone to mitigate its impact on the healthcare system and ICU units.