Identification of Streptococcus pneumoniae in hospital-acquired pneumonia in adults

Antibacterial activity of Hungarian varietal honeys against respiratory pathogens as a function of storage time

Today, antibiotic therapies that previously worked well against certain bacteria due to their natural sensitivity, are becoming less effective. Honey has been proven to inhibit the biofilm formation of some respiratory bacteria, however few data are available on how the storage time affects the antibacterial effect. The activity of black locust, goldenrod, linden and sunflower honeys from three consecutive years (2020, 2021, 2022) was analyzed in 2022 against Gram-negative (Haemophilus influenzae, H. parainfluenzae, Pseudomonas aeruginosa) and Gram-positive (Streptococcus pneumoniae) bacteria using in vitro microbiological methods. After determining the physicochemical parameters of honey, broth microdilution was applied to determine the minimum inhibitory concentration of each honey type against each bacterium, and crystal violet assay was used to test their antibiofilm effect. The possible mechanism of action was explored with membrane degradation test, while structural changes were illustrated with scanning electron microscopy. Honeys stored for one or two years were darker than fresh honeys, while older honeys had significantly lower antibacterial activity. The most remarkable inhibitory effect was exerted by linden and sunflower honeys, and P. aeruginosa proved to be the most resistant bacterium. Based on our results, honey intended for medicinal purposes should be used as fresh as possible during a treatment.

Clinical challenge of diagnosing non-ventilator hospital-acquired pneumonia and identifying causative pathogens: a narrative review

Non-ventilated hospital-acquired pneumonia (NV-HAP) is associated with a significant healthcare burden, arising from high incidence and associated morbidity and mortality. However, accurate identification of cases remains challenging. At present, there is no gold-standard test for the diagnosis of NV-HAP, requiring instead the blending of non-specific signs and investigations. Causative organisms are only identified in a minority of cases. This has significant implications for surveillance, patient outcomes and antimicrobial stewardship. Much of the existing research in HAP has been conducted among ventilated patients. The paucity of dedicated NV-HAP research means that conclusions regarding diagnostic methods, pathology and interventions must largely be extrapolated from work in other settings. Progress is also limited by the lack of a widely agreed definition for NV-HAP. The diagnosis of NV-HAP has large scope for improvement. Consensus regarding a case definition will allow meaningful research to improve understanding of its aetiology and the heterogeneity of outcomes experienced by patients. There is potential to optimize the role of imaging and to incorporate novel techniques to identify likely causative pathogens. This would facilitate both antimicrobial stewardship and surveillance of an important healthcare-associated infection. This narrative review considers the utility of existing methods to diagnose NV-HAP, with a focus on the significance and challenge of identifying pathogens. It discusses the limitations in current techniques, and explores the potential of emergent molecular techniques to improve microbiological diagnosis and outcomes for patients.

Environmental factors and particle size shape the community structure of airborne total and pathogenic bacteria in a university campus

Given the dense population on university campuses, indoor and outdoor airborne bacterial contamination may lead to the rapid spread of diseases in a university environment. However, there are few studies of the characteristics of airborne and pathogenic bacterial communities in different sites on a university campus. In this study, we collected particulate matter samples from indoor and outdoor locations at a university in Bengbu City, Anhui Province, China, and analyzed the community characteristics of airborne and pathogenic bacteria using a high-throughput sequencing technique. The results showed that the composition of the dominant airborne and pathogenic bacterial communities was consistent among sites at the phylum and genus levels, with differences in their relative abundance. There were significant differences in the structure of the airborne and pathogenic bacterial communities between indoor and outdoor sites (p < 0.05). An analysis of similarities (ANOSIM) indicated that the structure of airborne bacterial communities in indoor sites was influenced by the room occupancy rate, ventilation conditions, and the extent of indoor furnishing (p < 0.05), while the structure of pathogenic bacterial communities was influenced by the number of individuals and spatial dimensions (p < 0.05). The impact of particle size on the structure of airborne and pathogenic bacterial communities was relatively minor. A total of 194 suspected pathogenic bacterial species were identified, accounting for 0.0001-1.3923% of the total airborne bacteria, all of which were conditional pathogens. Among them, Saccharopolyspora rectivirgula, Acinetobacter johnsonii, and Moraxella osloensis exhibited relatively high relative abundance, accounting for 24.40, 16.22, and 8.66% of the total pathogenic bacteria, respectively. Moreover, 18 emerging or re-emerging pathogenic bacterial species with significant implications for human health were identified, although their relative abundance was relatively low (0.5098%). The relative abundance of pathogenic bacteria in indoor environments was significantly higher than outdoors, with the laboratory and dormitory having the highest levels. The findings of this study provide valuable guidance for the prevention and control of airborne bacterial contamination and the associated health risks in both a campus environment and other public spaces with high occupancy rates.

Understanding blaNDM-1 gene regulation in CRKP infections: toward novel antimicrobial strategies for hospital-acquired pneumonia

BACKGROUND

The escalating challenge of Carbapenem-resistant Klebsiella pneumoniae (CRKP) in hospital-acquired pneumonia (HAP) is closely linked to the blaNDM-1 gene. This study explores the regulatory mechanisms of blaNDM-1 expression and aims to enhance antibacterial tactics to counteract the spread and infection of resistant bacteria.

METHODS

KP and CRKP strains were isolated from HAP patients' blood samples. Transcriptomic sequencing (RNA-seq) identified significant upregulation of blaNDM-1 gene expression in CRKP strains. Bioinformatics analysis revealed blaNDM-1 gene involvement in beta-lactam resistance pathways. CRISPR-Cas9 was used to delete the blaNDM-1 gene, restoring sensitivity. In vitro and in vivo experiments demonstrated enhanced efficacy with Imipenem and Thanatin or Subatan combination therapy.

RESULTS

KP and CRKP strains were isolated with significant upregulation of blaNDM-1 in CRKP strains identified by RNA-seq. The Beta-lactam resistance pathway was implicated in bioinformatics analysis. Knockout of blaNDM-1 reinstated sensitivity in CRKP strains. Further, co-treatment with Imipenem, Thanatin, or Subactam markedly improved antimicrobial effectiveness.

CONCLUSION

Silencing blaNDM-1 in CRKP strains from HAP patients weakens their Carbapenem resistance and optimizes antibacterial strategies. These results provide new theoretical insights and practical methods for treating resistant bacterial infections.

Graphene oxide-based colorimetric/fluorescence dual-mode immunochromatography assay for simultaneous ultrasensitive detection of respiratory virus and bacteria in complex samples

A point-of-care testing biosensor that supports direct, sensitive, and simultaneous identification of bacteria and virus is still lacking. In this study, an ultrasensitive immunochromatography assay (ICA) with colorimetric/fluorescence dual-signal output was proposed for flexible and accurate detection of respiratory virus and bacteria in complex samples. Colorimetric AuNPs of 16 nm and two layers of quantum dots (QDs) were coated onto the surface of monolayer graphene oxide (GO) layer by layer to form a multilayered dual-signal nanofilm. This material not only can generate strong colorimetric and fluorescence signals for ICA analysis but also can provide larger surface area, better stability, and superior dispersibility than conventional spherical nanomaterials. Two test lines were built onto the ICA strip to simultaneously detect common respiratory virus influenza A and respiratory bacteria Streptococcus pneumoniae. The dual-signal mode of assay greatly broadened the applied range of ICA method, in which the colorimetric mode allows for quick determination of virus/bacteria and the fluorescence mode ensures the highly sensitive and quantitative detection of target pathogens with detection limits down to 891 copies/mL and 17 cells/mL, respectively. The proposed dual-mode ICA can also be applied directly for real biological and environment samples, which suggests its great potential for field application.

Evaluation of a Rapid Urine Antigen Detection Assay as a Point-of-Care Test in the Diagnosis of Community-Acquired Pneumonia

Introduction Community-acquired pneumonia (CAP) is among the most common public health problems encountered throughout the world. CAP is a frequent cause of lower respiratory tract infections among children and geriatric-age persons. The etiology of CAP is complex but generally involves infection with bacteria like Streptococcus pneumoniae (S. pneumoniae), which is the most common cause of CAP. The underdiagnosis of CAP due to the limitations of conventional culture methods could be responsible for severe morbidity and mortality, especially among susceptible populations. We evaluated the usefulness of a rapid immunochromatographic test (BinaxNOW™, Abbott, Chicago, IL) that detects S. pneumoniae through a rapid urine antigen test (RUAT) as a point-of-care (POC) diagnostic method in the early detection of CAP. Methods A prospective study was conducted in a university-affiliated teaching hospital between January 2019 and September 2019 (nine months). The study recruited 300 inpatients who revealed signs and symptoms associated with pneumonia. The study was approved by the institutional ethics committee, and all participants provided their voluntary informed consent. Laboratory evaluation included the collection of sputum samples, which were processed for Gram stain and routine culture. Five milliliters of blood were collected from all the subjects for carrying out a blood culture. A urine sample was collected from each participant for the detection of S. pneumoniae through the point-of-care urinary antigen test. Results Of the 300 patients diagnosed with CAP, the S. pneumoniae RUAT was positive in 110 out of 140 cases of pneumococcal pneumoniae (78.57%). The RUAT results were positive for 20 (66.6%) out of 30 bacteremic patients and for 90 (81.8%) out of 110 patients positive for sputum culture. The RUAT was positive in 10 out of 20 cases of pneumonia with an unknown microbial etiology. The overall sensitivity (78.57%), specificity (100%), positive predictive value (100%), negative predictive value (98.88%), and accuracy (90%) of the RUAT were similar to sputum culture results.  Conclusion The RUAT has shown comparable efficacy with sputum culture and therefore can be used as a complementary approach to conventional methods in the early diagnosis of CAP caused by S. pneumoniae. Due to its ease of use and rapid results, it could be incorporated as a POC diagnostic test.

Serum Krebs von den Lungen-6 is associated with in-Hospital mortality of patients with severe Community-Acquired Pneumonia: A retrospective cohort study

BACKGROUND

Currently, no ideal biomarker can accurately stratify the risk of patients with severe community-acquired pneumonia (SCAP). This study aimed to evaluate the role of serum Krebs von den Lungen-6 (sKL-6) in predicting in-hospital mortality in adults with SCAP.

METHODS

In this retrospective cohort study, 249 severe pneumonia adult patients were recruited between 6 May 2021 to 30 April 2023 in Xiangya Hospital of Central South University. The sKL-6 level within 48 h of admission was measured, and the primary outcome assessed was in-hospital mortality. Multivariable logistic regression analysis was performed to calculate adjusted odds ratios (OR) with 95% confidence intervals (CI). Survival curves were plotted and subgroup analyses were conducted, stratified by relevant covariates.

RESULTS

A total of 249 patients were included in the study,with 124 patients having normal sKL-6 levels, and 125 patients having abnormal sKL-6 levels. The overall in-hospital mortality rate was 28.9% (72 out of 249 patients). Univariate and multivariate logistic regression analysis revealed that the patients with abnormal sKL-6 levels had a higher risk of in-hospital mortality compared to those with normal sKL-6 levels, both in the total SCAP patient population (OR: 5.38, 95%CI: 2.41-12.01, P < 0.001) and the non-COVID-19 SCAP patients subgroup (OR: 8.12, 95%CI: 3.16-20.84, P < 0.001). Subgroup and interaction analyses confirmed the stability of the relationship between sKL-6 levels and in-hospital mortality(P for interaction > 0.05). Kaplan-Meier survival curves showed that patients with abnormal sKL-6 levels had a higher in-hospital mortality rate than those with normal sKL-6 levels (P < 0.05). However, the results of restricted cubic spline plots(RCS) analysis demonstrated a nonlinear association between sKL-6 levels (as a continuous variable) and in-hospital mortality in patients with SCAP. Similar results were observed in non-COVID-19 SCAP patients. Furthermore, the receiver operating characteristic curve (ROC) analysis revealed that sKL-6 had superior predictive performance compared to existing biomarkers (e.g., APACHE-II, SOFA, BUN/Cr, PCT, and D-dimer) for in-hospital mortality in non-COVID-19 SCAP patients.

CONCLUSION

sKL-6 is a practical and useful biomarker for predicting in-hospital mortality in patients with SCAP.

Glucose levels affect MgaSpn regulation on the virulence and adaptability of Streptococcus pneumoniae

Streptococcus pneumoniae can regulate virulence gene expression by sensing environmental changes, which is key to its pathogenicity. The global transcription regulator MgaSpn of Streptococcus pneumoniae regulates virulence genes expression by directly binding to the promoter regions, but its role in response to different environments remains unclear. In this study, we found that glucose levels could affect phosphocholine content, which was mediated by MgaSpn. MgaSpn can also alter its anti-phagocytosis ability, depending on the availability of glucose. In addition, transcriptome analysis of wild-type D39s in low and high glucose concentrations revealed that MgaSpn was also involved in the regulation of carbon metabolism inhibition (carbon catabolite repression; CCR) and translation processes, which made S. pneumoniae highly competitive in fluctuating environments. In conclusion, MgaSpn is closely related to the virulence and environmental adaptability of Streptococcus pneumoniae.

Catalisis, enzimas y pruebas rápidas

Un gran número de los procesos metabólicos y biológicos son catalizados por enzimas; las enzimas son compuestos químicos orgánicos que pertenecen al grupo específico de las biomoléculas denominadas proteínas. Las enzimas poseen en su estructura molecular cuaternaria, organizaciones internas que permiten definir un lugar denominado centro activo; su función química, cinética y termodinámica se relacionan con la disminución de la energía de activación en el curso de la reacción neta. Los mecanismos de reacción enzimáticos que suceden en las interacciones metabólicas de los microorganismos han permitido desarrollar una serie de pruebas cualitativas que determinan la presencia o ausencia de bacterias en una muestra o un cultivo haciendo uso de técnicas rápidas que facilitan el diagnóstico clínico.

Cytokines help suggest aplastic anemia with pulmonary bacterial or co-fungal infection

Although aplastic anemia (AA) does not come under the category of blood malignant diseases, the infection that frequently occurs in this bone marrow failure can make it worse. Pulmonary infection is the most prevalent but limiting clinical diagnosis. To find biomarkers predicting bacterial or bacterial-combined fungal infections in the lungs, we reviewed 287 AA medical records including 151 without any infection, 87 with pure pulmonary bacterial infection, and 49 with bacterial and fungal infection were reviewed. There were substantial changes in IL-17F, IL-17A, IFN-γ, IL-6, IL-8, and IL-10 levels between the non-infected and lung bacterial infection groups (P < 0.05). Further, a significant variation in IL-17A, TNF-β, IL-1β, IL-2, IL-4, IL-6, IL-8, IL-10, IL-22, and IL-12p70, between the uninfected group and the pulmonary bacterial and fungal infection group (P < 0.05) was observed. The results further revealed significant differences in TNF-β, IL-12p70, IL-6, IL-8, and IL-10 between the pulmonary bacterial infection group and the fungal infection group (P < 0.05). Moreover, by calculating ROC and cut-off values, we determined that IL-6 (AUC = 0.98, Cut-off = 14.28 pg/ml, P = 0.0000) had a significant advantage than other cytokines, body temperature (AUC = 0.61, P = 0.0050), PCT (AUC = 0.57, P = 0.0592), and CRP (AUC = 0.60, P = 0.0147) in the detection of lungs bacterial infections. In addition, IL-6 (AUC = 1.00, Cut-off = 51.50 pg/ml, P = 0.000) and IL-8 (AUC = 0.87, Cut-off = 60.53 pg/ml, P = 0.0000) showed stronger advantages than other cytokines, body temperature (AUC = 0.60, P = 0.0324), PCT (AUC = 0.72, Cut-off = 0.63 ng/ml, P = 0.0000) and CRP (AUC = 0.79, Cut-off = 5.79 mg/l, P = 0.0000) in distinguishing bacteria from fungi. This may suggest that IL-8 may play a role in differentiating co-infected bacteria and fungi. Such advantages are repeated in severe aplastic anemia (SAA) and very severe aplastic anemia (VSAA).In conclusion, aberrant IL-6 elevations in AA patients may predict the likelihood of bacterial lung infection. The concurrent increase of IL-6 and IL-8, on the other hand, should signal bacterial and fungal infections in patients.These findings may help to suggest bacterial or fungal co-infection in patients with AA (Focus on VSAA and SAA).

Application of Metagenomic Next-Generation Sequencing (mNGS) Using Bronchoalveolar Lavage Fluid (BALF) in Diagnosing Pneumonia of Children

Pneumonia is the leading cause of death in children; the pathogens are often difficult to diagnose. In this study, the performance of metagenomic next-generation sequencing (mNGS) using bronchoalveolar lavage fluid (BALF) samples from 112 children with confirmed pneumonia has been evaluated. mNGS performed a significantly higher positive detection rate (91.07%, 95% confidence interval [CI] 83.80% to 95.40%) and coincidence rate against the final diagnosis (72.32%, 95% CI 62.93% to 80.15%) than that of conventional methods (70.54%, 95% CI 61.06% to 78.58% and 56.25%, 95% CI 46.57% to 65.50%, respectively) (P < 0.01 and P < 0.05, respectively). Bacteria, viruses, and their mixed infections were common in children with pneumonia. Streptococcus pneumoniae was the most common bacterial pathogen in children with pneumonia, while Haemophilus parainfluenzae and Haemophilus influenzae seemed more likely to cause nonsevere pneumonia in children. In contrast, human cytomegalovirus (CMV) infection and the simultaneous bacterial infections could cause severe pneumonia, especially in children with underlying diseases. After adjustments of antibiotics based on mNGS and conventional methods, the conditions improved in 109 (97.32%) children. mNGS of BALF samples has shown great advantages in diagnosing the pathogenic etiology of pneumonia in children, especially when considering the limited volumes of BALF and the previous use of empirical antibiotics, contributing to the timely adjustment of antibiotic treatments, which can potentially improve the prognosis and decrease the mortality. IMPORTANCE Our study indicates high efficiency of mNGS using BALF for the detection of causative pathogens that cause pneumonia in children. mNGS can be a potential diagnostic tool to supplement conventional methods for children's pneumonia.

Immortelle (Helichrysum italicum (Roth) G. Don) Essential Oil Showed Antibacterial and Biofilm Inhibitory Activity against Respiratory Tract Pathogens

The biofilm formation of bacteria in different parts of the human body can influence the success of antibiotic therapy. Essential oils (EOs) and their components are becoming increasingly popular in point of view of medicinal applications, because of their antibacterial efficacy. The immortelle EO has been used traditionally as an expectorant; however, there are no studies summarizing its antibacterial effect against respiratory tract bacteria. Our aim was to investigate the antibacterial and biofilm inhibitory activity of immortelle (Helichrysum italicum) EO against respiratory tract pathogens such as Haemophilus influenzae, H. parainfluenzae, Pseudomonas aeruginosa and Streptococcus pneumoniae. In order to prove the antibacterial effect of the immortelle EO, broth microdilution and biofilm inhibition tests, and membrane damage assay were investigated. Scanning electron microscopy was used to identify the structural modifications in bacterial cells. Our results showed that immortelle EO has antibacterial and anti-biofilm effects against respiratory tract bacteria used in this study. H. parainfluenzae was the most sensitive to each treatment, however, P. aeruginosa was the most resistant bacteria. In conclusion, the studied EO may have a role in the treatment of respiratory tract infections due to their antibacterial and anti-biofilm activity.

Mechanistic Understanding of Lung Inflammation: Recent Advances and Emerging Techniques

Acute respiratory distress syndrome (ARDS) is a life-threatening lung injury characterized by an acute inflammatory response in the lung parenchyma. Hence, it is considered as the most appropriate clinical syndrome to study pathogenic mechanisms of lung inflammation. ARDS is associated with increased morbidity and mortality in the intensive care unit (ICU), while no effective pharmacological treatment exists. It is very important therefore to fully characterize the underlying pathobiology and the related mechanisms, in order to develop novel therapeutic approaches. In vivo and in vitro models are important pre-clinical tools in biological and medical research in the mechanistic and pathological understanding of the majority of diseases. In this review, we will present data from selected experimental models of lung injury/acute lung inflammation, which have been based on clinical disorders that can lead to the development of ARDS and related inflammatory lung processes in humans, including ventilation-induced lung injury (VILI), sepsis, ischemia/reperfusion, smoke, acid aspiration, radiation, transfusion-related acute lung injury (TRALI), influenza, Streptococcus (S.) pneumoniae and coronaviruses infection. Data from the corresponding clinical conditions will also be presented. The mechanisms related to lung inflammation that will be covered are oxidative stress, neutrophil extracellular traps, mitogen-activated protein kinase (MAPK) pathways, surfactant, and water and ion channels. Finally, we will present a brief overview of emerging techniques in the field of omics research that have been applied to ARDS research, encompassing genomics, transcriptomics, proteomics, and metabolomics, which may recognize factors to help stratify ICU patients at risk, predict their prognosis, and possibly, serve as more specific therapeutic targets.

The application of ambroxol hydrochloride combined with fiberoptic bronchoscopy in elderly patients with severe pneumonia: A meta-analysis and systematic review

BACKGROUND

The role of ambroxol hydrochloride combined with fiberoptic bronchoscopy in elderly patients with severe pneumonia remains unclear, we aimed to analyze this issue to provide evidences into the management of clinical pneumonia.

METHODS

We searched PubMed et al databases up to October 20, 2021 for the randomized controlled trials on the application of ambroxol hydrochloride combined with fiberoptic bronchoscopy in elderly patients with severe pneumonia. Related outcomes were extracted and analyzed. Review Manager 5.3 software was used for data analysis.

RESULTS

A total of 13 randomized controlled trials involving 1317 elderly patients (559 cases in the ambroxol hydrochloride + fiberoptic bronchoscopy group and 658 cases in the fiberoptic bronchoscopy group) with pneumonia were included. Meta-analyses indicated that the blood oxygen partial pressure [mean difference (MD) = 5.75, 95% confidence interval (CI) (3.80, 7.70)], blood oxygen saturation [MD = 6.43, 95% CI (4.39, 8.48)], oxygenation index [MD = 26.75, 95% CI (14.61, 38.89)] of experimental group was significantly higher than that of control group (all P < .001), the incidence of multiple organ failure [odds ratio = 0.42, 95% CI (0.31, 0.56), P < .001], mortality on day 28 [odds ratio = 0.44, 95% CI (0.33, 0.59)] of experimental group was significantly less than that of control group (all P < .001).

CONCLUSIONS

The high-dose ambroxol hydrochloride combined with fiberoptic bronchoscopy is beneficial to improve the patient's blood gas indicators, and reduce mortality in elderly patients with severe pneumonia.

A spectrum-effect based method for screening antibacterial constituents in Niuhuang Shangqing Pill using comprehensive two-dimensional liquid chromatography

To investigate and screen the active antibacterial constituents of Niuhuang Shangqing Pill (NSP), the current study developed a two-dimensional liquid chromatography (2DLC) method combining microcalorimetry technique. 60% ethanol extracts from 10 batches of different commercial NSP samples were analyzed and their chemical fingerprint were developed by the comprehensive 2DLC system of Shimadzu Nexera X2. Anti-streptococcus pneumoniae (SP) constituents were determined by microcalorimetry. Thermal kinetic parameters of the SP thermogram affected by 60% ethanol extracts from 10 NSP samples were analyzed by principal component analysis. Spectrum-effect correlation between comprehensive 2DLC fingerprint and the antibacterial activity were analyzed by orthogonal partial least squares (OPLS) and orthogonal partial least squares discriminant analysis (OPLS-DA). Findings showed that peak X1 (unknown), X9 (aloe-emodin), X10 (baicalein), X11 (unknown), X14 (wogonin), X15 (glycyrrhizic acid) and X17 (unknown) are the relevant components that are in positive correlation with inhibitory rate. Regarding inhibitory rate, X17 is the most powerful one, followed by X14, X15, X10, X11, X1 and X9, suggesting that compound X17, wogonin, glycyrrhizic acid and baicalein are the major active antibacterial components of NSP. The current method employing 2DLC with microcalorimetry technique proposes a new insight for screening and identifying antibacterial components in complex herbal formula.

In Vitro Antibacterial and Antibiofilm Activity of Hungarian Honeys against Respiratory Tract Bacteria

Honey is a rich source of carbohydrates, while minor compounds such as amino acids and polyphenols contribute to its health-promoting effects. Honey is one of the oldest traditional remedies applied for microbial infections, due to its antibacterial, anti-inflammatory, and antioxidant properties. The aim of this study was to investigate the antibacterial and antibiofilm effects of Hungarian black locust, linden, and sunflower honeys against the most common biofilm-forming respiratory tract pathogens Haemophilus spp., Pseudomonas aeruginosa, and Streptococcus pneumoniae. The unifloral character of all three honey types was confirmed by melissopalynological analysis. The antibacterial activity of each honey sample against each bacterium strain was proven with agar well diffusion assay and thin layer chromatography—direct bioautography. Kinetics and mechanisms of antibacterial action were clarified with time-kill assay and membrane degradation study. The anti-biofilm activity was evidenced using crystal violet assay. In each assay, linden honey was the most effective, followed by sunflower and black locust honey. In addition, each honey sample had greater potential to suppress respiratory tract bacteria, compared to major sugar components. In conclusion, honey in general and linden honey in particular, can have a role in the treatment of respiratory tract infections caused by biofilm-forming bacteria.