Sinensetin interferes with Staphylococcus aureus infections by targeting staphylocoagulase and improves infection survival rates in mouse model of pneumonia.

AIMS: Coagulase (Coa), a crucial virulence factor of Staphylococcus aureus (S. aureus), is considered a vital target for anti-virulence strategies. The research aimed to discover a natural compound capable of inhibiting S. aureus infection by targeting the virulence factor Coa. METHODS AND RESULTS: The study showed that sinensetin at a concentration of 128 µg mL-1 effectively inhibited both Coa-induced coagulation and biofilm formation in S. aureus. However, western blot results indicated that sinensetin did not impact the expression of Coa protein, suggesting that sinensetin may directly target Coa to counteract the virulence of S. aureus. Thermal shift assay results demonstrated that sinensetin enhanced the thermal stability of Coa, supporting the theory of direct binding. Molecular docking and point mutation experiments identified two key binding sites for sinensetin to Coa as R73A-Coa and R204A-Coa. In vivo studies on mice revealed that sinensetin not only reduced lung tissue damage caused by S. aureus infection, but also decreased inflammatory factors in the lung lavage fluid. Furthermore, combining sinensetin with oxacillin improved the survival rates of the Galleria mellonella and mice. CONCLUSIONS: Sinensetin is a promising natural compound that acts as a direct inhibitor of Coa against S. aureus infections.

Ectopic Expression of C-Type Lectin Mincle Renders Mice Susceptible to Staphylococcal Pneumonia.

Staphylococcus aureus is a prevalent pathogen in pneumonia and harbors glycolipids, which may serve as molecular patterns in Mincle (macrophage-inducible C-type lectin)-dependent pathogen recognition. We examined the role of Mincle in lung defense against S aureus in wild-type (WT), Mincle knockout (KO), and Mincle transgenic (tg) mice. Two glycolipids, glucosyl-diacylglycerol (Glc-DAG) and diglucosyl-diacylglycerol (Glc2-DAG), were purified, of which only Glc-DAG triggered Mincle reporter cell activation and professional phagocyte responses. Proteomic profiling revealed that Glc2-DAG blocked Glc-DAG-induced cytokine responses, thereby acting as inhibitor of Glc-DAG/Mincle signaling. WT mice responded to S aureus with a similar lung pathology as Mincle KO mice, most likely due to Glc2-DAG-dependent inhibition of Glc-DAG/Mincle signaling. In contrast, ectopic Mincle expression caused severe lung pathology in S aureus-infected mice, characterized by bacterial outgrowth and fatal pneumonia. Collectively, Glc2-DAG inhibits Glc-DAG/Mincle-dependent responses in WT mice, whereas sustained Mincle expression overrides Glc2-DAG-mediated inhibitory effects, conferring increased host susceptibility to S aureus.

Inhibitory effect of Jingfang mixture on Staphylococcus aureus α-hemolysin.

Staphylococcus aureus is a gram-positive bacteria, and its virulence factors can cause many kinds of infections, such as pneumonia, sepsis, enteritis and osteomyelitis. Traditional antibiotics can not only kill bacteria, but also easily lead to bacterial resistance. Jingfang Mixture (JFM) has the effects of inducing sweating and relieving the exterior, dispelling wind and eliminating dampness, and is commonly used in clinic to prevent and treat epidemic diseases and infectious diseases. The main purpose of this study is to explore the inhibitory effect of JFM on alpha-hemolysin (Hla) of S. aureus and to alleviate the damage caused by Hla. We found that JFM could inhibit the hemolytic activity, transcription level and neutralizing activity of Hla in a dose-dependent manner at the concentrations of 125, 250 and 500 µg/mL, without affecting the growth of bacteria. In addition, JFM reduced the damage of Hla to A549 cells and the release of lactate dehydrogenase (LDH). We also observed that in the S. aureus - induced pneumonia mouse model, JFM could significantly prolong the life of mice, reduce the bacterial load in the lungs, significantly improve the pathological state of the lungs and alleviate the damage caused by inflammatory factors, and the pathogenicity of gene deletion strain DU 1090 of S. aureus to pneumonia mice was also significantly reduced. In conclusion, this study proved that JFM is a potential drug against S. aureus infection, and this study provided a preliminary study for better guidance of clinical drug use.

Hla protein expression and artesunate prevented mice from further damage caused by Staphylococcus aureus pneumonia.

The laboratory standard MRSA strain WHO-2 and clinical isolate S1 were used to establish a pneumonia infection model. The results showed that methicillin increased the expression of Hla and PVL protein at subminimum inhibitory concentration, while artesunate decreased the secretion of Hla and PVL protein. Artesunate alone reduced hemolysin expression and reversed methicillin-induced increases in Hla and PVL proteins. In addition, the study found that the combination of artesunate and methicillin had the best therapeutic effect, with survival rates of 70 % and 40 % at seven days, respectively (corresponding to the WHO-2 and S1 strains). The combination treatment was able to reduce cell mortality, showing a 65 % and 46 % reduction in cell mortality, respectively. The study also found that the combination therapy decreased the expression of alpha-hemolysin and pantone valentin leukin in the culture medium and significantly reduced the activation of NF-kB. This is caused by a significant decrease in the expression of inflammatory factors.

miR-155 promotes Th17 differentiation by targeting FOXP3 to aggravate inflammation in MRSA pneumonia.

BACKGROUND: Previous researches have clarified that miR-155 is increased in methicillin-resistant Staphylococcus aureus (MRSA) pneumonia, and modulates Th9 differentiation. Like Th9 cells, Th17 cells were also a subset of CD4+ T cells and involved in MRSA pneumonia progression. This work aimed to investigate the role and mechanism of miR-155 in Th17 differentiation. METHODS: Bronchoalveolar lavage fluid (BALF) was collected from children with MRSA pneumonia and bronchial foreign bodies. MRSA-infected murine model was established followed by collecting BALF and lung tissues. qRT-PCR, ELISA and flow cytometry were performed to examine the mRNA expression and concentration of IL-17 and the number of Th17 cells in above samples. HE and ELISA were used to evaluate inflammatory responses in lung. Furthermore, CD4+ T cells were isolated from BALF of children for in vitro experiments. After treatments with miR-155 mimic/inhibitor, the roles of miR-155 in Th17/IL-17 regulation were determined. The downstream of miR-155 was explored by qRT-PCR, western blotting, dual luciferase reporter analysis and RIP assay. RESULTS: The levels of IL-17 and the proportion of Th17 cells were increased in children with MRSA pneumonia. A similar pattern was observed in MRSA-infected mice. On the contrary, IL-17 neutralization abolished the activation of Th17/IL-17 induced by MRSA infection. Furthermore, IL-17 blockade diminished the inflammation caused by MRSA. In vitro experiments demonstrated miR-155 positively regulated IL-17 expression and Th17 differentiation. Mechanistically, FOXP3 was a direct target of miR-155. miR-155 inhibited FOXP3 level via binding between FOXP3 and Argonaute 2 (AGO2), the key component of RNA-induced silencing complex (RISC). FOXP3 overexpression reversed elevated IL-17 levels and Th17 differentiation induced by miR-155. CONCLUSIONS: miR-155 facilitates Th17 differentiation by reducing FOXP3 through interaction of AGO2 and FOXP3 to promote the pathogenesis of MRSA pneumonia. IL-17 blockade weakens the inflammation due to MRSA, which provides a nonantibiotic treatment strategy for MRSA pneumonia.

HDAC6 inhibitor promotes reactive oxygen species-meditated clearance of Staphylococcus aureus in macrophage.

Staphylococcus aureus (S. aureus) pneumonia has become an increasingly important public health problem. Recent evidence suggests that epigenetic modifications are critical in the host immune defence against pathogen infection. In this study, we found that S. aureus infection induces the expression of histone deacetylase 6 (HDAC6) in a dose-dependent manner. Furthermore, by using a S. aureus pneumonia mouse model, we showed that the HDAC6 inhibitor, tubastatin A, demonstrates a protective effect in S. aureus pneumonia, decreasing the mortality and destruction of lung architecture, reducing the bacterial burden in the lungs and inhibiting inflammatory responses. Mechanistic studies in primary bone marrow-derived macrophages demonstrated that the HDAC6 inhibitors, tubastatin A and tubacin, reduced the intracellular bacterial load by promoting bacterial clearance rather than regulating phagocytosis. Finally, N-acetyl-L- cysteine, a widely used reactive oxygen species (ROS) scavenger, antagonized ROS production and significantly inhibited tubastatin A-induced S. aureus clearance. These findings demonstrate that HDAC6 inhibitors promote the bactericidal activity of macrophages by inducing ROS, an important host factor for S. aureus clearance and production. Our study identified HDAC6 as a suitable epigenetic modification target for preventing S. aureus infection, and tubastatin A as a useful compound in treating S. aureus pneumonia.

Lincosamide monotherapy treatment of methicillin-resistant Staphylococcus aureus pneumonia in tropical Australia: a case series.

Existing recommended first-line antibiotic agents for MRSA pneumonia have several shortcomings. We reviewed 29 cases of community- and hospital-acquired MRSA pneumonia managed at our hospital. Lincosamide monotherapy was administered to 21/29 (72%) and was the predominant antibiotic regimen (> 50% course duration) in 19/29 (66%). Patients receiving lincosamide-predominant monotherapy were no more likely to die or require intensive care unit admission than patients receiving vancomycin-predominant monotherapy (5/19 (26%) versus 4/7 (57%), p = 0.19); 5/7 (71%) patients admitted to ICU and 4/5 (80%) bacteraemic patients received lincosamide-predominant monotherapy. MRSA pneumonia can be safely treated with lincosamide monotherapy if the isolate is susceptible.

MI-DenseCFNet: deep learning-based multimodal diagnosis models for Aureus and Aspergillus pneumonia.

OBJECTIVE: To build and merge a diagnostic model called multi-input DenseNet fused with clinical features (MI-DenseCFNet) for discriminating between Staphylococcus aureus pneumonia (SAP) and Aspergillus pneumonia (ASP) and to evaluate the significant correlation of each clinical feature in determining these two types of pneumonia using a random forest dichotomous diagnosis model. This will enhance diagnostic accuracy and efficiency in distinguishing between SAP and ASP. METHODS: In this study, 60 patients with clinically confirmed SAP and ASP, who were admitted to four large tertiary hospitals in Kunming, China, were included. Thoracic high-resolution CT lung windows of all patients were extracted from the picture archiving and communication system, and the corresponding clinical data of each patient were collected. RESULTS: The MI-DenseCFNet diagnosis model demonstrates an internal validation set with an area under the curve (AUC) of 0.92. Its external validation set demonstrates an AUC of 0.83. The model requires only 10.24s to generate a categorical diagnosis and produce results from 20 cases of data. Compared with high-, mid-, and low-ranking radiologists, the model achieves accuracies of 78% vs. 75% vs. 60% vs. 40%. Eleven significant clinical features were screened by the random forest dichotomous diagnosis model. CONCLUSION: The MI-DenseCFNet multimodal diagnosis model can effectively diagnose SAP and ASP, and its diagnostic performance significantly exceeds that of junior radiologists. The 11 important clinical features were screened in the constructed random forest dichotomous diagnostic model, providing a reference for clinicians. CLINICAL RELEVANCE STATEMENT: MI-DenseCFNet could provide diagnostic assistance for primary hospitals that do not have advanced radiologists, enabling patients with suspected infections like Staphylococcus aureus pneumonia or Aspergillus pneumonia to receive a quicker diagnosis and cut down on the abuse of antibiotics. KEY POINTS: • MI-DenseCFNet combines deep learning neural networks with crucial clinical features to discern between Staphylococcus aureus pneumonia and Aspergillus pneumonia. • The comprehensive group had an area under the curve of 0.92, surpassing the proficiency of junior radiologists. • This model can enhance a primary radiologist's diagnostic capacity.

Predictive value of methicillin-resistant staphylococcus aureus nasal swab in patients with COVID-19 pneumonia and secondary bacterial pneumonia.

OBJECTIVE: To determine the performance measures of admission methicillin-resistant Staphylococcus aureus (MRSA) nasal swabs for MRSA bacterial pneumonia in patients co-infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). METHODS: The study included patients admitted with SARS-CoV-2-positive nasopharyngeal specimens, MRSA nasal screens, and bacterial cultures to assess secondary MRSA pneumonia. RESULTS: 293 patients and 662 microbiological cultures evaluated. Overall, the specificity (91.8% [95% CI 88.6% to 95%]) and negative predictive value (NPV 97.4% [95% CI 95.4% - 99.3%]) of MRSA nasal swabs was high. However, the sensitivity (46.2%; 95% CI 19.1% to 73.3%) and positive predictive value (PPV 20.7%; 95% CI 59.5 - 35.4%) were low. Those patients in the MRSA nasal swab negative group had a shorter median duration of linezolid therapy. CONCLUSIONS: SARS-CoV-2 infection doesn't reduce the specificity or negative predictive value of MRSA nasal swabs for secondary MRSA pneumonia.

Targeted proteomics links virulence factor expression with clinical severity in staphylococcal pneumonia.

Introduction: The bacterial pathogen Staphylococcus aureus harbors numerous virulence factors that impact infection severity. Beyond virulence gene presence or absence, the expression level of virulence proteins is known to vary across S. aureus lineages and isolates. However, the impact of expression level on severity is poorly understood due to the lack of high-throughput quantification methods of virulence proteins. Methods: We present a targeted proteomic approach able to monitor 42 staphylococcal proteins in a single experiment. Using this approach, we compared the quantitative virulomes of 136 S. aureus isolates from a nationwide cohort of French patients with severe community-acquired staphylococcal pneumonia, all requiring intensive care. We used multivariable regression models adjusted for patient baseline health (Charlson comorbidity score) to identify the virulence factors whose in vitro expression level predicted pneumonia severity markers, namely leukopenia and hemoptysis, as well as patient survival. Results: We found that leukopenia was predicted by higher expression of HlgB, Nuc, and Tsst-1 and lower expression of BlaI and HlgC, while hemoptysis was predicted by higher expression of BlaZ and HlgB and lower expression of HlgC. Strikingly, mortality was independently predicted in a dose-dependent fashion by a single phage-encoded virulence factor, the Panton-Valentine leucocidin (PVL), both in logistic (OR 1.28; 95%CI[1.02;1.60]) and survival (HR 1.15; 95%CI[1.02;1.30]) regression models. Discussion: These findings demonstrate that the in vitro expression level of virulence factors can be correlated with infection severity using targeted proteomics, a method that may be adapted to other bacterial pathogens.

Bavachin Suppresses Alpha-Hemolysin Expression and Protects Mice from Pneumonia Infection by Staphylococcus aureus.

Staphylococcus aureus (S. aureus) infection causes dramatic harm to human health as well as to livestock development. As an important virulence factor, alpha-hemolysin (hla) is critical in the process of S. aureus infection. In this report, we found that bavachin, a natural flavonoid, not only efficiently inhibited the hemolytic activity of hla, but was also capable of inhibiting it on transcriptional and translational levels. Moreover, further data revealed that bavachin had no neutralizing activity on hla, which did not affect the formation of hla heptamers and exhibited no effects on the hla thermal stability. In vitro assays showed that bavachin was able to reduce the S. aureus-induced damage of A549 cells. Thus, bavachin repressed the lethality of pneumonia infection, lung bacterial load and lung tissue inflammation in mice, providing potent protection to mice models in vivo. Our results indicated that bavachin has the potential for development as a candidate hla inhibitor against S. aureus.

Novel Requirement for Staphylococcal Cell Wall-Anchored Protein SasD in Pulmonary Infection.

Staphylococcus aureus can complicate preceding viral infections, including influenza virus. A bacterial infection combined with a preceding viral infection, known as superinfection, leads to worse outcomes than a single infection. Most of the pulmonary infection literature focuses on the changes in immune responses to bacteria between homeostatic and virally infected lungs. However, it is unclear how much of an influence bacterial virulence factors have in single or superinfection. Staphylococcal species express a broad range of cell wall-anchored proteins (CWAs) that have roles in host adhesion, nutrient acquisition, and immune evasion. We screened the importance of these CWAs using mutants lacking individual CWAs in vivo in both bacterial pneumonia and influenza superinfection. In bacterial pneumonia, the lack of individual CWAs leads to various decreases in bacterial burden, lung damage, and immune infiltration into the lung. However, the presence of a preceding influenza infection partially abrogates the requirement for CWAs. In the screen, we found that the uncharacterized CWA S. aureus surface protein D (SasD) induced changes in both inflammatory and homeostatic lung markers. We further characterized a SasD mutant (sasD A50.1) in the context of pneumonia. Mice infected with sasD A50.1 have decreased bacterial burden, inflammatory responses, and mortality compared to wild-type S. aureus. Mice also have reduced levels of interleukin-1ß (IL-1ß), likely derived from macrophages. Reductions in IL-1ß transcript levels as well as increased macrophage viability point at differences in cell death pathways. These data identify a novel virulence factor for S. aureus that influences inflammatory signaling within the lung. IMPORTANCE Staphylococcus aureus is a common commensal bacterium that can cause severe infections, such as pneumonia. In the lung, viral infections increase the risk of staphylococcal pneumonia, leading to combined infections known as superinfections. The most common virus associated with S. aureus pneumonia is influenza, and superinfections lead to worse patient outcomes than either infection alone. While there is much known about how the immune system differs between healthy and virally infected lungs, the role of bacterial virulence factors in single and superinfection is less understood. The significance of our research is identifying bacterial components that play a role in the initiation of lung injury, which could lead to future therapies to prevent pulmonary single or superinfection with S. aureus.

Natural flavone hispidulin protects mice from Staphylococcus aureus pneumonia by inhibition of α-hemolysin production via targeting AgrAC.

The emergence of drug-resistant Staphylococcus aureus (S. aureus) has limited drug options for the clinical treatment of S. aureus infections. Considering recent reports, therapeutic strategies targeting bacterial virulence hold great promise, and alpha-hemolysin (encoded by hla), a critical virulence factor of S. aureus, plays a vital role during bacterial infection. Herein, we demonstrated that hispidulin effectively inhibited the hemolytic activity of S. aureus USA300 without suppressing bacterial growth, along with inhibiting hla transcription and expression in a dose-dependent manner. As heptamer formation is essential for hla-mediated invasion of cells, nevertheless, hispidulin did not affect the deoxycholate-induced oligomerization of hla, suggesting that hispidulin did not affect the protein activity of hla. In vitro assays illustrated that hispidulin bound to agrAC, a crucial protein in quorum sensing. Meanwhile, hispidulin alleviated A549 cell damage caused by S. aureus USA300 and reduced lactate dehydrogenase release. In vivo studies showed that hispidulin had a protective effect against pneumonia caused by S. aureus USA300 in mice. S. aureus did not develop resistance to hispidulin in the short term. Interestingly, our research indicated that hispidulin synergized with the antibacterial activity of cefoxitin. These results showed that hispidulin effectively inhibited α-hemolysin expression by inhibiting the agr quorum sensing of S. aureus. It has promise as an agent to treat S. aureus infection.

Methicillin-Resistant Staphylococcus aureus Hospital-Acquired Pneumonia/Ventilator-Associated Pneumonia.

Methicillin-resistant Staphylococcus aureus (MRSA) is a common cause of hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP). MRSA pneumonia is associated with significant morbidity and mortality. Several virulence factors allow S. aureus to become an effective pathogen. The polysaccharide intracellular adhesin allows for the production of biofilms, some strains can produce capsular polysaccharides that protect against phagocytosis, microbial surface components recognizing adhesive matrix molecules (MSCRAMMs) allow for colonization of epithelial surfaces, and S. aureus secretes several exotoxins that aid in tissue destruction. The α-hemolysin exotoxin secreted by S. aureus is one of the most important virulence factors for the bacteria. The diagnosis of MRSA pneumonia can be challenging; the infection may present as a mild respiratory infection or severe respiratory failure and septic shock. Many individuals are colonized with MRSA and thus a positive nasopharyngeal swab does not confirm infection in the lower respiratory tract. The management of MRSA pneumonia has evolved. Historically, vancomycin has been the primary antibiotic used to treat MRSA pneumonia. Over the past decade, prospective studies have shown that linezolid leads to higher rates of clinical cure. Monoclonal antibodies are being studied as potential therapeutic options. MRSA is an important cause of HAP/VAP; novel diagnostics may facilitate rapid diagnosis of this infection and the available literature should be used to make informed decisions on management.

Benefits of Aerosolized Phages for the Treatment of Pneumonia Due to Methicillin-Resistant Staphylococcus aureus: An Experimental Study in Rats.

BACKGROUND: The optimal method for delivering phages in the context of ventilator-associated pneumonia (VAP) is unknown. In the current study, we assessed the utility of aerosolized phages (aerophages) for experimental methicillin-resistant Staphylococcus aureus (MRSA) pneumonia. METHODS: Rats were ventilated for 4 hours before induction of pneumonia. Animals received one of the following: (1) aerophages; (2) intravenous (IV) phages; (3) a combination of IV and aerophages; (4) IV linezolid; or (5) a combination of IV linezolid and aerophages. Phages were administered at 2, 12, 24, 48, and 72 hours, and linezolid was administered at 2, 12, 24, 36, 48, 60, and 72 hours. The primary outcome was survival at 96 hours. Secondary outcomes were bacterial and phage counts in tissues and histopathological scoring of the lungs. RESULTS: Aerophages and IV phages each rescued 50% of animals from severe MRSA pneumonia (P < .01 compared with placebo controls). The combination of aerophages and IV phages rescued 91% of animals, which was higher than either monotherapy (P < .05). Standard-of-care antibiotic linezolid rescued 38% of animals. However, linezolid and aerophages did not synergize in this setting (55% survival). CONCLUSIONS: Aerosolized phage therapy showed potential for the treatment of MRSA pneumonia in an experimental animal model and warrants further investigation for application in humans.

Association between mortality and highly antimicrobial-resistant bacteria in intensive care unit-acquired pneumonia.

Data on the relationship between antimicrobial resistance and mortality remain scarce, and this relationship needs to be investigated in intensive care units (ICUs). The aim of this study was to compare the ICU mortality rates between patients with ICU-acquired pneumonia due to highly antimicrobial-resistant (HAMR) bacteria and those with ICU-acquired pneumonia due to non-HAMR bacteria. We conducted a multicenter, retrospective cohort study using the French National Surveillance Network for Healthcare Associated Infection in ICUs ("REA-Raisin") database, gathering data from 200 ICUs from January 2007 to December 2016. We assessed all adult patients who were hospitalized for at least 48 h and presented with ICU-acquired pneumonia caused by S. aureus, Enterobacteriaceae, P. aeruginosa, or A. baumannii. The association between pneumonia caused by HAMR bacteria and ICU mortality was analyzed using the whole sample and using a 1:2 matched sample. Among the 18,497 patients with at least one documented case of ICU-acquired pneumonia caused by S. aureus, Enterobacteriaceae, P. aeruginosa, or A. baumannii, 3081 (16.4%) had HAMR bacteria. The HAMR group was associated with increased ICU mortality (40.3% vs. 30%, odds ratio (OR) 95%, CI 1.57 [1.45-1.70], P < 0.001). This association was confirmed in the matched sample (3006 HAMR and 5640 non-HAMR, OR 95%, CI 1.39 [1.27-1.52], P < 0.001) and after adjusting for confounding factors (OR ranged from 1.34 to 1.39, all P < 0.001). Our findings suggest that ICU-acquired pneumonia due to HAMR bacteria is associated with an increased ICU mortality rate, ICU length of stay, and mechanical ventilation duration.

Antimicrobial activity of dalbavancin and comparators against Staphylococcus aureus causing pneumonia in patients with and without cystic fibrosis.

The activities of dalbavancin and comparator agents were evaluated against Staphylococcus aureus isolated from the lower respiratory tract of cystic fibrosis (CF) and non-CF patients with pneumonia. Bacterial isolates (n = 357) were collected from CF patients in 36 medical centers worldwide (2018-2019) and susceptibility tested using reference broth microdilution. Susceptibility results from these isolates were compared with those for 725 S. aureus isolates consecutively collected from non-CF patients with pneumonia from the same medical centers over the same period. Only isolates determined to be the probable cause of pneumonia were included in the study. Susceptibility profiles were very similar among isolates from CF and non-CF patients. Dalbavancin exhibited potent activity (MIC50/90, 0.03/0.03 mg/L) and complete coverage (100.0% susceptibility) against isolates from CF and non-CF patients. Ceftaroline (MIC50/90, 0.25/1 mg/L) was active against 97.8% and 98.1% of isolates from CF and non-CF patients, respectively. Oxacillin resistance (MRSA) rates were 27.7% among CF and 28.7% among non-CF patients. Among MRSA isolates from CF/non-CF patients (n = 99/208), susceptibility to ceftaroline, clindamycin, levofloxacin, and tetracycline were 91.9%/93.3%, 58.6%/64.4%, 40.4%/29.3%, and 83.8%/89.4%, respectively. Dalbavancin demonstrated high potency against S. aureus from CF and non-CF patients and may represent a valuable treatment option for CF patients with MRSA pulmonary infection.

Pulmonary Infections and Surgical Complications in a Young Girl with Signal Transducer and Activator of Transcription 3 Loss-of-Function Mutation Hyperimmunoglobulin E Syndrome: A Case Report.

Introduction: Hyperimmunoglobulin E syndromes (HIESs) are characterized by a high serum immunoglobulin E (IgE) level, eczematoid rashes, recurrent staphylococcal skin abscesses, and recurrent pneumonia and pneumatocele formation. Autosomal dominant HIES is the most common form of HIES and mainly occurs due to loss-of-function mutations in the Signal Transducer and Activator of Transcription 3 (STAT3) gene (STAT3 LOF). Case Presentation: We report the case of an 11-year-old Peruvian girl diagnosed with STAT3 LOF caused by p.R382W mutation. She presented with recurrent staphylococcal pneumonia and empyema caused by the rarely reported Achromobacter xylosoxidans, which led to severe destruction of the lung parenchyma, multiple lung surgeries, and the development of bronchopleural fistulas. A laparotomy was also performed, which showed evidence of sigmoid colon perforation. The patient received immunoglobulin replacement therapy (IRT) and antibiotic prophylaxis, and the frequency of her infections has decreased over the past 3 years. Conclusion: This is the first case of STAT3 LOF diagnosed by genomic sequencing in Peru. Patients with this mutation have recurrent pulmonary infections, and require multiple surgical procedures with frequent complications. A. xylosoxidans infection could be related to the prolonged stay in intensive care leading to high mortality; therefore, additional care must be taken when treating patients with this infection. In addition, colonic perforation is a rare complication in STAT3 LOF patients. IRT and antibiotic prophylaxis appear to decrease the frequency of infections and hospitalizations.

Infectious aetiologies of severe acute chest syndrome in sickle-cell adult patients, combining conventional microbiological tests and respiratory multiplex PCR.

Acute chest syndrome (ACS) is the most serious complication of sickle cell disease. The pathophysiology of ACS may involve lower respiratory tract infection (LRTI), alveolar hypoventilation and atelectasis, bone infarcts-driven fat embolism, and in situ pulmonary artery thrombosis. One of the most challenging issues for the physicians is to diagnose LRTI as the cause of ACS. The use of a respiratory multiplex PCR (mPCR) for the diagnosis of LRTI has not been assessed in sickle-cell adult patients with ACS. To describe the spectrum of infectious aetiologies of severe ACS, using a diagnostic approach combining conventional tests and mPCR. A non-interventional monocenter prospective study involving all the consecutive sickle-cell adult patients with ACS admitted to the intensive care unit (ICU). Microbiological investigation included conventional tests and a nasopharyngeal swab for mPCR. Altogether, 36 patients were enrolled, of whom 30 (83%) had complete microbiological investigations. A bacterial microorganism, mostly Staphylococcus aureus (n = 8), was identified in 11 patients. There was no pneumonia-associated intracellular bacterial pathogen. A respiratory virus was identified in six patients. Using both conventional tests and nasopharyngeal mPCR, a microbiological documentation was obtained in half of adult ACS patients admitted to the ICU. Pyogenic bacteria, especially S. aureus, predominated.