Global initiative for meticillin-resistant Staphylococcus aureus pneumonia (GLIMP): an international, observational cohort study

Research progress on the role and inhibitors of Keap1 signaling pathway in inflammation

Inflammation is a protective mechanism against endogenous and exogenous pathogens. It is a typical feature of numerous chronic diseases and their complications. Keap1 is an essential target in oxidative stress and inflammatory diseases. Among them, the Keap1-Nrf2-ARE pathway (including Keap1-Nrf2-HO-1) is the most significant pathway of Keap1 targets, which participates in the control of inflammation in multiple organs (including renal inflammation, lung inflammation, liver inflammation, neuroinflammation, etc.). Identifying new Keap1 inhibitors is crucial for new drug discovery. However, most drugs have specificity issues as they covalently bind to cysteine residues of Keap1, causing off-target effects. Therefore, direct inhibition of Keap1-Nrf2 PPIs is a new research idea. Through non-electrophilic and non-covalent binding, its inhibitors have better specificity and ability to activate Nrf2, and targeting therapy against Keap1-Nrf2 PPIs has become a new method for drug development in chronic diseases. This review summarizes the members and downstream genes of the Keap1-related pathway and their roles in inflammatory disease models. In addition, we summarize all the research progress of anti-inflammatory drugs targeting Keap1 from 2010 to 2024, mainly describing their biological functions, molecular mechanisms of action, and therapeutic roles in inflammatory diseases.

Community-Acquired Pneumonia: A Review

Importance

Community-acquired pneumonia (CAP) results in approximately 1.4 million emergency department visits, 740 000 hospitalizations, and 41 000 deaths in the US annually.

Observations

Community-acquired pneumonia can be diagnosed in a patient with 2 or more signs (eg, temperature >38 °C or ≤36 °C; leukocyte count <4000/μL or >10 000/μL) or symptoms (eg, new or increased cough or dyspnea) of pneumonia in conjunction with consistent radiographic findings (eg, air space density) without an alternative explanation. Up to 10% of patients with CAP are hospitalized; of those, up to 1 in 5 require intensive care. Older adults (≥65 years) and those with underlying lung disease, smoking, or immune suppression are at highest risk for CAP and complications of CAP, including sepsis, acute respiratory distress syndrome, and death. Only 38% of patients hospitalized with CAP have a pathogen identified. Of those patients, up to 40% have viruses identified as the likely cause of CAP, with Streptococcus pneumoniae identified in approximately 15% of patients with an identified etiology of the pneumonia. All patients with CAP should be tested for COVID-19 and influenza when these viruses are common in the community because their diagnosis may affect treatment (eg, antiviral therapy) and infection prevention strategies. If test results for influenza and COVID-19 are negative or when the pathogens are not likely etiologies, patients can be treated empirically to cover the most likely bacterial pathogens. When selecting empirical antibacterial therapy, clinicians should consider disease severity and evaluate the likelihood of a bacterial infection-or resistant infection-and risk of harm from overuse of antibacterial drugs. Hospitalized patients without risk factors for resistant bacteria can be treated with β-lactam/macrolide combination therapy, such as ceftriaxone combined with azithromycin, for a minimum of 3 days. Systemic corticosteroid administration within 24 hours of development of severe CAP may reduce 28-day mortality.

Conclusions

Community-acquired pneumonia is common and may result in sepsis, acute respiratory distress syndrome, or death. First-line therapy varies by disease severity and etiology. Hospitalized patients with suspected bacterial CAP and without risk factors for resistant bacteria can be treated with β-lactam/macrolide combination therapy, such as ceftriaxone combined with azithromycin, for a minimum of 3 days.

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.

Sono-Triggered Biomimetically Nanoantibiotics Mediate Precise Sequential Therapy of MRSA-Induced Lung Infection

Bacterial-induced lower respiratory tract infections are a growing global health concern, exacerbated by the inefficacy of conventional antibiotics and delivery methods to effectively target the lower respiratory tract, leading to suboptimal therapeutic outcomes. To address this challenge, this work engineers PBP2a antibody-presenting membrane nanovesicles (AMVs) specifically designed to target the penicillin-binding protein variant on the surface of methicillin-resistant Staphylococcus aureus (MRSA). Concurrently, this work develops pure ciprofloxacin nanoparticles (NanoCip) that, for the first time, exhibits exceptional self-generated sonodynamic properties, attributed to hydrogen-bond-driven self-assembly, while maintaining their inherent pharmacological efficacy. These NanoCip particles are integrated with AMVs to create a novel biomimetic nanomedicine, AMV@NanoCip. This formulation demonstrated remarkable MRSA-targeting affinity in both in vitro and in vivo models, significantly enhancing antibacterial activity. Upon ultrasound stimulation, AMV@NanoCip achieves over 99.99% sterilization of MRSA in vitro, with a reduction exceeding 5.14 Log CFU. Prokaryotic transcriptomic analysis further elucidates the synergistic mechanisms by which AMV@NanoCip, coupled with ultrasound, disrupts the MRSA exoskeleton. In a MRSA-induced pneumonia animal model, AMV@NanoCip+US results in a substantial bacterial load reduction in the lungs (99.99%, 4.02 Log CFU). This sequential treatment strategy (adhesion-membrane disruption-synergistic therapy) offers significant promise as an innovative therapeutic approach for combating bacterial infections.

Aspirin reduces the mortality risk of patients with community-acquired pneumonia: a retrospective propensity-matched analysis of the MIMIC-IV database

Background

Community-acquired pneumonia (CAP) is a common infectious disease characterized by inflammation of the lung parenchyma in individuals who have not recently been hospitalized. It remains a significant cause of morbidity and mortality worldwide. Aspirin is a widely used drug, often administered to CAP patients. However, the benefits of aspirin remain controversial.

Objective

We sought to determine whether aspirin treatment has a protective effect on the outcomes of CAP patients.

Methods

We selected patients with CAP from the Medical Information Mart for Intensive Care IV (MIMIC-IV) database. Propensity score matching (PSM) balanced baseline differences. A multivariate Cox regression model assessed the relationship between aspirin treatment and 28-day mortality.

Results

A total of 3,595 patients were included, with 2,261 receiving aspirin and 1,334 not. After PSM, 1,219 pairs were matched. The 28-day mortality rate for aspirin users was 20.46%, lower than non-users. Multivariate Cox regression indicated aspirin use was associated with decreased 28-day mortality (HR 0.75, 95% CI 0.63-0.88, p < 0.001). No significant differences were found between 325 mg/day and 81 mg/day aspirin treatments in terms of 28-day mortality, hospital mortality, 90-day mortality, gastrointestinal hemorrhage, and thrombocytopenia. However, intensive care unit (ICU) stay was longer for the 325 mg/day group compared to the 81 mg/day group (4.22 vs. 3.57 days, p = 0.031).

Conclusion

Aspirin is associated with reduced 28-day mortality in CAP patients. However, 325 mg/day aspirin does not provide extra benefits over 81 mg/day and may lead to longer ICU stays.

Global, regional, and national incidence and mortality burden of non-COVID-19 lower respiratory infections and aetiologies, 1990-2021: a systematic analysis from the Global Burden of Disease Study 2021

BACKGROUND

Lower respiratory infections (LRIs) are a major global contributor to morbidity and mortality. In 2020-21, non-pharmaceutical interventions associated with the COVID-19 pandemic reduced not only the transmission of SARS-CoV-2, but also the transmission of other LRI pathogens. Tracking LRI incidence and mortality, as well as the pathogens responsible, can guide health-system responses and funding priorities to reduce future burden. We present estimates from the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2021 of the burden of non-COVID-19 LRIs and corresponding aetiologies from 1990 to 2021, inclusive of pandemic effects on the incidence and mortality of select respiratory viruses, globally, regionally, and for 204 countries and territories.

METHODS

We estimated mortality, incidence, and aetiology attribution for LRI, defined by the GBD as pneumonia or bronchiolitis, not inclusive of COVID-19. We analysed 26 259 site-years of mortality data using the Cause of Death Ensemble model to estimate LRI mortality rates. We analysed all available age-specific and sex-specific data sources, including published literature identified by a systematic review, as well as household surveys, hospital admissions, health insurance claims, and LRI mortality estimates, to generate internally consistent estimates of incidence and prevalence using DisMod-MR 2.1. For aetiology estimation, we analysed multiple causes of death, vital registration, hospital discharge, microbial laboratory, and literature data using a network analysis model to produce the proportion of LRI deaths and episodes attributable to the following pathogens: Acinetobacter baumannii, Chlamydia spp, Enterobacter spp, Escherichia coli, fungi, group B streptococcus, Haemophilus influenzae, influenza viruses, Klebsiella pneumoniae, Legionella spp, Mycoplasma spp, polymicrobial infections, Pseudomonas aeruginosa, respiratory syncytial virus (RSV), Staphylococcus aureus, Streptococcus pneumoniae, and other viruses (ie, the aggregate of all viruses studied except influenza and RSV), as well as a residual category of other bacterial pathogens.

FINDINGS

Globally, in 2021, we estimated 344 million (95% uncertainty interval [UI] 325-364) incident episodes of LRI, or 4350 episodes (4120-4610) per 100 000 population, and 2·18 million deaths (1·98-2·36), or 27·7 deaths (25·1-29·9) per 100 000. 502 000 deaths (406 000-611 000) were in children younger than 5 years, among which 254 000 deaths (197 000-320 000) occurred in countries with a low Socio-demographic Index. Of the 18 modelled pathogen categories in 2021, S pneumoniae was responsible for the highest proportions of LRI episodes and deaths, with an estimated 97·9 million (92·1-104·0) episodes and 505 000 deaths (454 000-555 000) globally. The pathogens responsible for the second and third highest episode counts globally were other viral aetiologies (46·4 million [43·6-49·3] episodes) and Mycoplasma spp (25·3 million [23·5-27·2]), while those responsible for the second and third highest death counts were S aureus (424 000 [380 000-459 000]) and K pneumoniae (176 000 [158 000-194 000]). From 1990 to 2019, the global all-age non-COVID-19 LRI mortality rate declined by 41·7% (35·9-46·9), from 56·5 deaths (51·3-61·9) to 32·9 deaths (29·9-35·4) per 100 000. From 2019 to 2021, during the COVID-19 pandemic and implementation of associated non-pharmaceutical interventions, we estimated a 16·0% (13·1-18·6) decline in the global all-age non-COVID-19 LRI mortality rate, largely accounted for by a 71·8% (63·8-78·9) decline in the number of influenza deaths and a 66·7% (56·6-75·3) decline in the number of RSV deaths.

INTERPRETATION

Substantial progress has been made in reducing LRI mortality, but the burden remains high, especially in low-income and middle-income countries. During the COVID-19 pandemic, with its associated non-pharmaceutical interventions, global incident LRI cases and mortality attributable to influenza and RSV declined substantially. Expanding access to health-care services and vaccines, including S pneumoniae, H influenzae type B, and novel RSV vaccines, along with new low-cost interventions against S aureus, could mitigate the LRI burden and prevent transmission of LRI-causing pathogens.

FUNDING

Bill & Melinda Gates Foundation, Wellcome Trust, and Department of Health and Social Care (UK).

Incidence of drug-resistant pathogens in community-acquired pneumonia at a safety net hospital

The 2019 Infectious Diseases Society of America guideline for the management of community-acquired pneumonia (CAP) emphasizes the need for clinician to understand local epidemiological data to guide selection of appropriate treatment. Currently, the local distribution of causative pathogens and their associated resistance patterns in CAP is unknown. A retrospective observational study was performed of patients admitted to an 870-bed safety net hospital between March 2016 and March 2021 who received a diagnosis of CAP or healthcare-associated pneumonia within the first 48 hours of admission. The primary outcome was the incidence of CAP caused by methicillin-resistant Staphylococcus aureus (MRSA) or Pseudomonas aeruginosa (PsA) as determined by comparing the number of satisfactory sputum cultures or blood cultures with these drug-resistant organisms to the total number of reviewed patients. Secondary outcomes studied included risk factors associated with CAP caused by drug-resistant organisms, utilization of broad-spectrum antibiotics, appropriate antibiotic de-escalation within 72 hours, and treatment duration. In this 220-patient cohort, MRSA or PsA was isolated from three sputum cultures and no blood cultures. The local incidence of drug-resistant pathogens among the analyzed sample of CAP patients was 1.4% (n = 3/220). The overall incidence of CAP caused by MRSA or PsA among admitted patients is low at our safety-net county hospital. Future research is needed to identify local risk factors associated with the development of CAP caused by drug-resistant pathogens.IMPORTANCEThis study investigates the incidence of drug-resistant pathogens including methicillin-resistant Staphylococcus aureus and Pseudomonas aeruginosa among community-acquired pneumonia (CAP) patients at a safety net hospital. Understanding local bacteria resistance patterns when treating CAP is essential and supported by evidence-based guidelines. Our findings empower other clinicians to investigate resistance patterns at their own institutions and identify methods to improve antibiotic use. This has the potential to reduce the unnecessary use of broad-spectrum antibiotic agents and combat the development of antibiotic resistance.

Predictors of mortality in severe pneumonia patients: a systematic review and meta-analysis

BACKGROUND

Severe pneumonia has consistently been associated with high mortality. We sought to identify risk factors for the mortality of severe pneumonia to assist in reducing mortality for medical treatment.

METHODS

Electronic databases including PubMed, Web of Science, EMBASE, Cochrane Library, and Scopus were systematically searched till June 1, 2023. All human research were incorporated into the analysis, regardless of language, publication date, or geographical location. To pool the estimate, a mixed-effect model was used. The Newcastle-Ottawa Scale (NOS) was employed for assessing the quality of included studies that were included in the analysis.

RESULTS

In total, 22 studies with a total of 3655 severe pneumonia patients and 1107 cases (30.29%) of death were included in the current meta-analysis. Significant associations were found between age [5.76 years, 95% confidence interval [CI] (3.43, 8.09), P < 0.00001], male gender [odds ratio (OR) = 1.47, 95% CI (1.07, 2.02), P = 0.02], and risk of death from severe pneumonia. The comorbidity of neoplasm [OR = 3.37, 95% CI (1.07, 10.57), P = 0.04], besides the presence of complications such as diastolic hypotension [OR = 2.60, 95% CI (1.45, 4.67), P = 0.001], ALI/ARDS [OR = 3.63, 95% CI (1.78, 7.39), P = 0.0004], septic shock [OR = 9.43, 95% CI (4.39, 20.28), P < 0.00001], MOF [OR = 4.34, 95% CI (2.36, 7.95), P < 0.00001], acute kidney injury [OR = 2.45, 95% CI (1.14, 5.26), P = 0.02], and metabolic acidosis [OR = 5.88, 95% CI (1.51, 22.88), P = 0.01] were associated with significantly higher risk of death among patients with severe pneumonia. Those who died, compared with those who survived, differed on multiple biomarkers on admission including serum creatinine [Scr: + 67.77 mmol/L, 95% CI (47.21, 88.34), P < 0.00001], blood urea nitrogen [BUN: + 6.26 mmol/L, 95% CI (1.49, 11.03), P = 0.01], C-reactive protein [CRP: + 33.09 mg/L, 95% CI (3.01, 63.18), P = 0.03], leukopenia [OR = 2.63, 95% CI (1.34, 5.18), P = 0.005], sodium < 136 mEq/L [OR = 2.63, 95% CI (1.34, 5.18), P = 0.005], albumin [- 5.17 g/L, 95% CI (- 7.09, - 3.25), P < 0.00001], PaO2/FiO2 [- 55.05 mmHg, 95% CI (- 60.11, - 50.00), P < 0.00001], arterial blood PH [- 0.09, 95% CI (- 0.15, - 0.04), P = 0.0005], gram-negative microorganism [OR = 2.56, 95% CI (1.17, 5.62), P = 0.02], and multilobar or bilateral involvement [OR = 3.65, 95% CI (2.70, 4.93), P < 0.00001].

CONCLUSIONS

Older age and male gender might face a greater risk of death in severe pneumonia individuals. The mortality of severe pneumonia may also be significantly impacted by complications such diastolic hypotension, ALI/ARDS, septic shock, MOF, acute kidney injury, and metabolic acidosis, as well as the comorbidity of neoplasm, and laboratory indicators involving Scr, BUN, CRP, leukopenia, sodium, albumin, PaO2/FiO2, arterial blood PH, gram-negative microorganism, and multilobar or bilateral involvement.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO Protocol Number: CRD 42023430684.

Guidelines for Antibiotics Prescription in Critically Ill Patients

How to cite this article: Khilnani GC, Tiwari P, Mittal S, Kulkarni AP, Chaudhry D, Zirpe KG, et al. Guidelines for Antibiotics Prescription in Critically Ill Patients. Indian J Crit Care Med 2024;28(S2):S104-S216.

A Rare Occurrence of Methicillin-Resistant Staphylococcus aureus (MRSA) Pneumonia Complicated by Nasal Vestibulitis and Orbital Cellulitis: A Case Report

We report the case of left lower lobe community-acquired methicillin-resistant Staphylococcus aureus (MRSA) pneumonia in an immunocompetent male in his 20s. His illness was complicated by the dramatic appearance of right nasal vestibulitis and right preseptal orbital cellulitis post-admission. The patient responded well to vancomycin and made a complete recovery. Community-acquired MRSA pneumonia in immunocompetent adults is a rare entity in India, and the combination with vestibulitis has not yet been reported. This hitherto unreported presentation sheds further light on the evolving pattern of MRSA infections in the community.

A targeted likelihood estimation comparing cefepime and piperacillin/tazobactam in critically ill patients with community-acquired pneumonia (CAP)

Cefepime and piperacillin/tazobactam are antimicrobials recommended by IDSA/ATS guidelines for the empirical management of patients admitted to the intensive care unit (ICU) with community-acquired pneumonia (CAP). Concerns have been raised about which should be used in clinical practice. This study aims to compare the effect of cefepime and piperacillin/tazobactam in critically ill CAP patients through a targeted maximum likelihood estimation (TMLE). A total of 2026 ICU-admitted patients with CAP were included. Among them, (47%) presented respiratory failure, and (27%) developed septic shock. A total of (68%) received cefepime and (32%) piperacillin/tazobactam-based treatment. After running the TMLE, we found that cefepime and piperacillin/tazobactam-based treatments have comparable 28-day, hospital, and ICU mortality. Additionally, age, PTT, serum potassium and temperature were associated with preferring cefepime over piperacillin/tazobactam (OR 1.14 95% CI [1.01-1.27], p = 0.03), (OR 1.14 95% CI [1.03-1.26], p = 0.009), (OR 1.1 95% CI [1.01-1.22], p = 0.039) and (OR 1.13 95% CI [1.03-1.24], p = 0.014)]. Our study found a similar mortality rate among ICU-admitted CAP patients treated with cefepime and piperacillin/tazobactam. Clinicians may consider factors such as availability and safety profiles when making treatment decisions.

Association between advanced lung cancer inflammation index and in-hospital mortality in ICU patients with community-acquired pneumonia: A retrospective analysis of the MIMIC-IV database

Objective

The objective of the present study was to explore the correlation between the advanced lung cancer inflammation index (ALI) and in-hospital mortality among patients diagnosed with community-acquired pneumonia (CAP).

Methods

Data from the Medical Information Mart for Intensive Care-IV database were adopted to analyze the in-hospital mortality of ICU patients with CAP. Upon admission to the ICU, fundamental data including vital signs, critical illness scores, comorbidities, and laboratory results, were collected. The in-hospital mortality of all CAP patients was documented. Multivariate logistic regression (MLR) models and restricted cubic spline (RCS) analysis together with subgroup analyses were conducted.

Results

This study includes 311 CAP individuals, involving 218 survivors as well as 93 nonsurvivors. The participants had an average age of 63.57 years, and the females accounted for approximately 45.33%. The in-hospital mortality was documented to be 29.90%. MLR analysis found that ALI was identified as an independent predictor for in-hospital mortality among patients with CAP solely in the Q1 group with ALI ≤ 39.38 (HR: 2.227, 95% CI: 1.026-4.831, P = 0.043). RCS analysis showed a nonlinear relationship between the ALI and in-hospital mortality, with a turning point at 81, and on the left side of the inflection point, a negative correlation was observed between ALI and in-hospital mortality (HR: 0.984, 95% CI: 0.975-0.994, P = 0.002). The subgroup with high blood pressure showed significant interaction with the ALI.

Conclusion

The present study demonstrated a nonlinear correlation of the ALI with in-hospital mortality among individuals with CAP. Additional confirmation of these findings requires conducting larger prospective investigations.

New Guidelines for Severe Community-acquired Pneumonia

In 2023, the new European guidelines on severe community-acquired pneumonia, providing clinical practice recommendations for the management of this life-threatening infection, characterized by a high burden of mortality, morbidity, and costs for the society. This review article aims to summarize the principal evidence related to eight different questions covered in the guidelines, by also highlighting the future perspectives for research activity.

Antibiotic Strategies for Severe Community-Acquired Pneumonia

Despite advancements in health systems and intensive care unit (ICU) care, along with the introduction of novel antibiotics and microbiologic techniques, mortality rates in severe community-acquired pneumonia (sCAP) patients have not shown significant improvement. Delayed admission to the ICU is a major risk factor for higher mortality. Apart from choosing the appropriate site of care, prompt and appropriate antibiotic therapy significantly affects the prognosis of sCAP. Treatment regimens involving ceftaroline or ceftobiprole are currently considered the best options for managing patients with sCAP. Additionally, several other molecules, such as delafloxacin, lefamulin, and omadacycline, hold promise as therapeutic strategies for sCAP. This review aims to provide a comprehensive summary of the key challenges in managing adults with severe CAP, focusing on essential aspects related to antibiotic treatment and investigating potential strategies to enhance clinical outcomes in sCAP patients.

QingXiaoWuWei decoction alleviates methicillin-resistant Staphylococcus aureus-induced pneumonia in mice by regulating metabolic remodeling and macrophage gene expression network via the microbiota-short-chain fatty acids axis

IMPORTANCE

Methicillin-resistant Staphylococcus aureus (MRSA) colonizes the upper respiratory airways and is resistant to antibiotics. MRSA is a frequently acquired infection in hospital and community settings, including cases of MRSA-induced pneumonia. Multidrug-resistant Staphylococcus aureus and the limited efficacy of antibiotics necessitate alternative strategies for preventing or treating the infection. QingXiaoWuWei decoction (QXWWD) protects against both gut microbiota dysbiosis and MRSA-induced pneumonia. Furthermore, the QXWWD-regulated metabolic remodeling and macrophage gene expression network contribute to its protective effects through the microbiota-short-chain fatty acid axis. The results of this study suggest that QXWWD and its pharmacodynamic compounds might have the potential to prevent and treat pulmonary infections, especially those caused by multidrug-resistant organisms. Our study provides a theoretical basis for the future treatment of pulmonary infectious diseases by manipulating gut microbiota and their metabolites via traditional Chinese medicine.

Metal nanoparticles as inhibitors of enzymes and toxins of multidrug-resistant Staphylococcus aureus

Staphylococcus aureus is an aerobic Gram-positive spherical bacterium known to cause a broad range of infections worldwide. It is a major cause of infective skin and soft infections and severe and life-threatening conditions, such as pneumonia, bloodstream infections, and endocarditis. The emergence of drug-resistant strains of S aureus, particularly methicillin-resistant S aureus (MRSA), has become a significant concern in the healthcare community. Antibiotic-resistant S aureus is commonly acquired in hospitals and long-term care facilities. It often affects patients with weakened immune systems, those undergoing invasive medical procedures, or those who have been hospitalized for extended periods. In the US, S aureus is known to cause potentially fatal illnesses, such as toxic shock syndrome (TSS) and acute-onset toxic shock syndrome (TSS), which are characterized by fever and hypotension. It develops resistance to antibiotics through several mechanisms, such as the production of enzymes that inactivate antibiotics, target site modification, efflux pumps, and plasmid-mediated resistance. Therefore, preventing the spread of drug-resistant S aureus is needed, and there is an urgent need to explore novel approaches in the development of anti-staphylococcal agents. This article reviews the principal infections caused by S aureus, major virulence factors, mechanisms of resistance development, and nanotechnology-based solutions for the control of drug-resistant S aureus.

Advances in antibacterial treatment of adults with high-risk febrile neutropenia

BACKGROUND

High-risk febrile neutropenia (HR-FN) is a life-threatening complication in patients with haematological malignancies or receiving myelosuppressive chemotherapy. Since the last international guidelines were published over 10 years ago, there have been major advances in the understanding and management of HR-FN, including on antibiotic pharmacokinetics and discontinuation/de-escalation strategies.

OBJECTIVES

Summarizing major advances in the field of antibacterial therapy in patients with HR-FN: empirical therapy, pharmacokinetics of antibiotics and antibiotic stewardship.

SOURCES

Narrative review based on literature review from PubMed. We focused on studies published between 2010 and 2023 about the pharmacokinetics of antimicrobials, management of antimicrobial administration, and discontinuation/de-escalation strategies. We did not address antimicrobial prophylaxis, viral or fungal infections.

CONTENT

Several high-quality publications have highlighted important modifications of antibiotic pharmacokinetics in HR-FN, with standard dosages exposing patients to underdosing. These recent clinical and population pharmacokinetics studies help improve management protocols with optimized initial dosing and infusion rules for β-lactams, vancomycin, daptomycin and amikacin; they highlight the potential benefits of therapeutic drug monitoring. A growing body of evidence also shows that antibiotic discontinuation/de-escalation strategies are beneficial for bacterial ecology and patients' outcome. We further discuss methods and limitations for implementation of such protocols in haematology.

IMPLICATIONS

We highlight recent information about the management of antibacterial therapy in HR-FN that might be considered in updated guidelines for HR-FN management.

Evaluation of the Effectiveness and Use of Anti-Methicillin-Resistant Staphylococcus aureus Agents for Aspiration Pneumonia in Older Patients Using a Nationwide Japanese Administrative Database

Studies indicated potential harm from empirical broad-spectrum therapy. A recent study of hospitalizations for community-acquired pneumonia suggested that empirical anti-methicillin-resistant Staphylococcus aureus (MRSA) therapy was associated with an increased risk of death and other complications. However, limited evidence supports empirical anti-MRSA therapy for older patients with aspiration pneumonia. In a nationwide Japanese database, patients aged ≥65 years on admission with aspiration pneumonia were analyzed. Patients were divided based on presence of respiratory failure and further sub-categorized based on their condition within 3 days of hospital admission, either receiving a combination of anti-MRSA agents and other antibiotics, or not using MRSA agents. An inverse probability weighting method with estimated propensity scores was used. Out of 81,306 eligible patients, 55,098 had respiratory failure, and 26,208 did not. In the group with and without respiratory failure, 0.93% and 0.42% of the patients, respectively, received anti-MRSA agents. In patients with respiratory failure, in-hospital mortality (31.38% vs. 19.03%, p < 0.001), 30-day mortality, and 90-day mortality were significantly higher, and oxygen administration length was significantly longer in the anti-MRSA agent combination group. Anti-MRSA agent combination use did not improve the outcomes in older patients with aspiration pneumonia and respiratory failure, and should be carefully and comprehensively considered.

ERS/ESICM/ESCMID/ALAT guidelines for the management of severe community-acquired pneumonia

PURPOSE

Severe community-acquired pneumonia (sCAP) is associated with high morbidity and mortality, and whilst European and non-European guidelines are available for community-acquired pneumonia, there are no specific guidelines for sCAP.

METHODS

The European Respiratory Society (ERS), European Society of Intensive Care Medicine (ESICM), European Society of Clinical Microbiology and Infectious Diseases (ESCMID), and Latin American Thoracic Association (ALAT) launched a task force to develop the first international guidelines for sCAP. The panel comprised a total of 18 European and four non-European experts, as well as two methodologists. Eight clinical questions for sCAP diagnosis and treatment were chosen to be addressed. Systematic literature searches were performed in several databases. Meta-analyses were performed for evidence synthesis, whenever possible. The quality of evidence was assessed with GRADE (Grading of Recommendations, Assessment, Development and Evaluation). Evidence to Decision frameworks were used to decide on the direction and strength of recommendations.

RESULTS

Recommendations issued were related to diagnosis, antibiotics, organ support, biomarkers and co-adjuvant therapy. After considering the confidence in effect estimates, the importance of outcomes studied, desirable and undesirable consequences of treatment, cost, feasibility, acceptability of the intervention and implications to health equity, recommendations were made for or against specific treatment interventions.

CONCLUSIONS

In these international guidelines, ERS, ESICM, ESCMID, and ALAT provide evidence-based clinical practice recommendations for diagnosis, empirical treatment, and antibiotic therapy for sCAP, following the GRADE approach. Furthermore, current knowledge gaps have been highlighted and recommendations for future research have been made.

Identify Drug-Resistant Pathogens in Patients with Community-Acquired Pneumonia

A substantial increase in broad-spectrum antibiotics as empirical therapy in patients with community-acquired pneumonia (CAP) has occurred over the last 15 years. One of the driving factors leading to that has been some evidence showing an increased incidence of drug-resistant pathogens (DRP) in patients from a community with pneumonia, including methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa. Research has been published attempting to identify DRP in CAP through the implementation of probabilistic approaches in clinical practice. However, recent epidemiological data showed that the incidence of DRP in CAP varies significantly according to local ecology, healthcare systems and countries where the studies were performed. Several studies also questioned whether broad-spectrum antibiotic coverage might improve outcomes in CAP, as it is widely documented that broad-spectrum antibiotics overuse is associated with increased costs, length of hospital stay, drug adverse events and resistance. The aim of this review is to analyze the different approaches used to identify DRP in CAP patients as well as the outcomes and adverse events in patients undergoing broad-spectrum antibiotics.

Impact of macrolide treatment on long-term mortality in patients admitted to the ICU due to CAP: a targeted maximum likelihood estimation and survival analysis

INTRODUCTION

Patients with community-acquired pneumonia (CAP) admitted to the intensive care unit (ICU) have high mortality rates during the acute infection and up to ten years thereafter. Recommendations from international CAP guidelines include macrolide-based treatment. However, there is no data on the long-term outcomes of this recommendation. Therefore, we aimed to determine the impact of macrolide-based therapy on long-term mortality in this population.

METHODS

Registered patients in the MIMIC-IV database 16 years or older and admitted to the ICU due to CAP were included. Multivariate analysis, targeted maximum likelihood estimation (TMLE) to simulate a randomised controlled trial, and survival analyses were conducted to test the effect of macrolide-based treatment on mortality six-month (6 m) and twelve-month (12 m) after hospital admission. A sensitivity analysis was performed excluding patients with Pseudomonas aeruginosa or MRSA pneumonia to control for Healthcare-Associated Pneumonia (HCAP).

RESULTS

3775 patients were included, and 1154 were treated with a macrolide-based treatment. The non-macrolide-based group had worse long-term clinical outcomes, represented by 6 m [31.5 (363/1154) vs 39.5 (1035/2621), p < 0.001] and 12 m mortality [39.0 (450/1154) vs 45.7 (1198/2621), p < 0.001]. The main risk factors associated with long-term mortality were Charlson comorbidity index, SAPS II, septic shock, and respiratory failure. Macrolide-based treatment reduced the risk of dying at 6 m [HR (95% CI) 0.69 (0.60, 0.78), p < 0.001] and 12 m [0.72 (0.64, 0.81), p < 0.001]. After TMLE, the protective effect continued with an additive effect estimate of - 0.069.

CONCLUSION

Macrolide-based treatment reduced the hazard risk of long-term mortality by almost one-third. This effect remains after simulating an RCT with TMLE and the sensitivity analysis for the HCAP classification.

Risk factors for developing ventilator-associated lower respiratory tract infection in patients with severe COVID-19: a multinational, multicentre study, prospective, observational study

Around one-third of patients diagnosed with COVID-19 develop a severe illness that requires admission to the Intensive Care Unit (ICU). In clinical practice, clinicians have learned that patients admitted to the ICU due to severe COVID-19 frequently develop ventilator-associated lower respiratory tract infections (VA-LRTI). This study aims to describe the clinical characteristics, the factors associated with VA-LRTI, and its impact on clinical outcomes in patients with severe COVID-19. This was a multicentre, observational cohort study conducted in ten countries in Latin America and Europe. We included patients with confirmed rtPCR for SARS-CoV-2 requiring ICU admission and endotracheal intubation. Only patients with a microbiological and clinical diagnosis of VA-LRTI were included. Multivariate Logistic regression analyses and Random Forest were conducted to determine the risk factors for VA-LRTI and its clinical impact in patients with severe COVID-19. In our study cohort of 3287 patients, VA-LRTI was diagnosed in 28.8% [948/3287]. The cumulative incidence of ventilator-associated pneumonia (VAP) was 18.6% [610/3287], followed by ventilator-associated tracheobronchitis (VAT) 10.3% [338/3287]. A total of 1252 bacteria species were isolated. The most frequently isolated pathogens were Pseudomonas aeruginosa (21.2% [266/1252]), followed by Klebsiella pneumoniae (19.1% [239/1252]) and Staphylococcus aureus (15.5% [194/1,252]). The factors independently associated with the development of VA-LRTI were prolonged stay under invasive mechanical ventilation, AKI during ICU stay, and the number of comorbidities. Regarding the clinical impact of VA-LRTI, patients with VAP had an increased risk of hospital mortality (OR [95% CI] of 1.81 [1.40-2.34]), while VAT was not associated with increased hospital mortality (OR [95% CI] of 1.34 [0.98-1.83]). VA-LRTI, often with difficult-to-treat bacteria, is frequent in patients admitted to the ICU due to severe COVID-19 and is associated with worse clinical outcomes, including higher mortality. Identifying risk factors for VA-LRTI might allow the early patient diagnosis to improve clinical outcomes.Trial registration: This is a prospective observational study; therefore, no health care interventions were applied to participants, and trial registration is not applicable.

ERS/ESICM/ESCMID/ALAT guidelines for the management of severe community-acquired pneumonia

BACKGROUND

Severe community-acquired pneumonia (sCAP) is associated with high morbidity and mortality, and while European and non-European guidelines are available for community-acquired pneumonia, there are no specific guidelines for sCAP.

MATERIALS AND METHODOLOGY

The European Respiratory Society (ERS), European Society of Intensive Care Medicine (ESICM), European Society of Clinical Microbiology and Infectious Diseases (ESCMID) and Latin American Thoracic Association (ALAT) launched a task force to develop the first international guidelines for sCAP. The panel comprised a total of 18 European and four non-European experts, as well as two methodologists. Eight clinical questions for sCAP diagnosis and treatment were chosen to be addressed. Systematic literature searches were performed in several databases. Meta-analyses were performed for evidence synthesis, whenever possible. The quality of evidence was assessed with GRADE (Grading of Recommendations, Assessment, Development and Evaluation). Evidence to Decision frameworks were used to decide on the direction and strength of recommendations.

RESULTS

Recommendations issued were related to diagnosis, antibiotics, organ support, biomarkers and co-adjuvant therapy. After considering the confidence in effect estimates, the importance of outcomes studied, desirable and undesirable consequences of treatment, cost, feasibility, acceptability of the intervention and implications to health equity, recommendations were made for or against specific treatment interventions.

CONCLUSIONS

In these international guidelines, ERS, ESICM, ESCMID and ALAT provide evidence-based clinical practice recommendations for diagnosis, empirical treatment and antibiotic therapy for sCAP, following the GRADE approach. Furthermore, current knowledge gaps have been highlighted and recommendations for future research have been made.

Prevalence and molecular characteristics of community-associated methicillin-resistant Staphylococcus aureus in the respiratory tracts of Chinese adults with community-acquired pneumonia

BACKGROUND

Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) is an important pathogen causing healthcare-associated infections. In recent years, an increasing number of CA-MRSA clones have emerged and rapidly spread in the community and hospital settings in China.

OBJECTIVES

To investigate the molecular epidemiology and resistance of CA-MRSA in the respiratory tracts of Chinese adults with community-acquired pneumonia (CAP).

METHODS

A total of 243 sputum samples were collected from adult patients with CAP at the Nantong Hospital in China between 2018 and 2021. S. aureus was identified using PCR, and its susceptibility to 14 antimicrobials was tested using the broth dilution method. Genomic characterization of respiratory CA-MRSA and our previously collected intestinal CA-MRSA isolates was performed using whole-genome sequencing, and the evolutionary relationships of these isolates were assessed using phylogenetic analysis.

RESULTS

The CA-MRSA colonization rate among adults with CAP in China was 7.8 % (19/243). Antimicrobial resistance analysis revealed that the proportion of multidrug-resistant respiratory CA-MRSA isolates (100 %) was higher than that of intestinal CA-MRSA isolates (6.3 %). Among the 35 CA-MRSA isolates, 10 MLST types were identified and clustered into five clone complexes (CCs). CC5 (48.6 %) and CC88 (20 %) were predominant CA-MRSA clones. Notably, the CC5 clone ST764/ST6292-MRSA-II-t002 was identified as the major lineage causing respiratory tract infections in Chinese adults with CAP.

CONCLUSIONS

The prevalence of CA-MRSA among Chinese adults with CAP is high and often involves ST764/ST6292-MRSA-II-t002 as the causal pathogen.

Bacterial Patterns and Empiric Antibiotic Use in COPD Patients With Community-Acquired Pneumonia

INTRODUCTION

Chronic obstructive pulmonary disease (COPD) is strongly associated with the development of community-acquired pneumonia (CAP). Limited data are available on risk factors for difficult to manage bacteria such as Pseudomonas aeruginosa in COPD patients with CAP. Our objective was to assess the microbiological patterns associated with risk factors that determine empiric antibiotic therapy in hospitalized COPD patients with CAP.

METHODS

We performed a secondary data analysis of an international, multicenter, observational, point-prevalence study involving hospitalized COPD patients with CAP from March to June 2015. After identifying the risk factors associated with different microorganisms, we developed a scoring system to guide decision-making about empiric anti-pseudomonal antibiotic therapy in this population.

RESULTS

We enrolled 689 hospitalized COPD patients with CAP with documented microbiological testing. The most frequent microorganisms isolated were Streptococcus pneumoniae (8%) and Gram-negative bacteria (8%), P. aeruginosa (7%) and Haemophilus influenzae (3%). We developed a scoring system incorporating the variables independently associated with P. aeruginosa that include a previous P. aeruginosa isolation or infection (OR 14.2 [95%CI 5.7-35.2]), hospitalization in the past 12 months (OR 3.7 [1.5-9.2]), and bronchiectasis (OR 3.2 [1.4-7.2]). Empiric anti-pseudomonal antibiotics were overutilized in COPD patients with CAP. The new scoring system has the potential to reduce empiric anti-pseudomonal antibiotic use from 54.1% to 6.2%.

CONCLUSIONS

COPD patients with CAP present different microbiological profiles associated with unique risk factors. Anti-pseudomonal treatment is a critical decision when selecting empiric antibiotic therapy. We developed a COPD scoring system to guide decision-making about empiric anti-pseudomonal antibiotic therapy.

Does etiological investigation have an impact on the outcomes of community-acquired pneumonia? - A prospective cohort study

INTRODUCTION

There is lack of evidence that etiological investigation influences outcomes in community-acquired pneumonia (CAP). Guidelines recommend diverse approaches to this matter. Our aim was to find if etiological investigation has an impact on CAP management and outcomes.

METHODS

Prospective cohort study, conducted over a two years' period, in a community-based hospital, including all adult patients with CAP. Univariate and multivariate logistic regression modeling were performed to understand the association of etiological identification with CAP outcomes, particularly hospital mortality.

RESULTS

A total of 660 cases of CAP were included, with a mean±sd age of 74±15 years and 58.9% of males. Etiology was documented in 33% of cases. Antibiotic (ATB) was modified in 148 patients, in 51 (34%) motivated by microbiological results. There was no significant impact on hospital mortality of microbiological documentation (35.5% vs 31.2%, p=0.352), or the fact that ATB was modified due to microbiological findings (27.0% vs 36.9%, p=0.272). When stratified by 3 subgroups of risk for drug-resistant pathogens (zero, one or two risk factors: being bed-ridden and/or ATB use within 90 days), etiology identification still did not influence mortality. When adjusted for CURB-65, Charlson's index, being bed-ridden, having had ATB or hospitalization within 90 days or coming from long-term care facilities, microbial identification was not associated with lower mortality.

CONCLUSION

Etiological investigation of patients with CAP does not have an association with hospital mortality, irrespective of the risk for drug-resistant pathogens.

Rapid identification of methicillin-resistant Staphylococcus aureus by MALDI-TOF MS: A meta-analysis

Invasive infections caused by methicillin-resistant Staphylococcus aureus (MRSA) are associated with high mortality and morbidity. The sooner the pathogen is determined, the better it is beneficial to patient. However, routine laboratory inspections are time-consuming and laborious. A thorough research was conducted in PubMed and Web of Science (until June 2021) to identify studies evaluating the accuracy of MRSA identification by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). STATA 15.0 software was used to analyze the pooled results of sensitivity, specificity, and 95% confidence intervals (CI). The summary receiver operating characteristic curves (SROC) and area under the curve (AUC) were utilized to show the overall performance of MALDI-TOF MS. Fifteen studies involving 2471 isolates were included in this study after the final selection in this meta-analysis. Using the random effects model forest plot to summarize the overall statistics, the sensitivity of MALDI-TOF MS for identifying MRSA was 92% (95% CI: 81%-97%), and the specificity was 97% (95% CI: 89%-99%). In the SROC curve, the AUC reached 0.99 (95% CI: 97%-99%). Deeks' test showed no significant publication bias in this meta-analysis. Compared with clinical reference methods, MALDI-TOF MS identification of MRSA shows a higher degree of sensitivity and specificity.

Superantigens, a Paradox of the Immune Response

Staphylococcal enterotoxins are a wide family of bacterial exotoxins with the capacity to activate as much as 20% of the host T cells, which is why they were called superantigens. Superantigens (SAgs) can cause multiple diseases in humans and cattle, ranging from mild to life-threatening infections. Almost all S. aureus isolates encode at least one of these toxins, though there is no complete knowledge about how their production is triggered. One of the main problems with the available evidence for these toxins is that most studies have been conducted with a few superantigens; however, the resulting characteristics are attributed to the whole group. Although these toxins share homology and a two-domain structure organization, the similarity ratio varies from 20 to 89% among different SAgs, implying wide heterogeneity. Furthermore, every attempt to structurally classify these proteins has failed to answer differential biological functionalities. Taking these concerns into account, it might not be appropriate to extrapolate all the information that is currently available to every staphylococcal SAg. Here, we aimed to gather the available information about all staphylococcal SAgs, considering their functions and pathogenicity, their ability to interact with the immune system as well as their capacity to be used as immunotherapeutic agents, resembling the two faces of Dr. Jekyll and Mr. Hyde.

Extracellular fibrinogen-binding protein released by intracellular Staphylococcus aureus suppresses host immunity by targeting TRAF3

Many pathogens secrete effectors to hijack intracellular signaling regulators in host immune cells to promote pathogenesis. However, the pathogenesis of Staphylococcus aureus secretory effectors within host cells is unclear. Here, we report that Staphylococcus aureus secretes extracellular fibrinogen-binding protein (Efb) into the cytoplasm of macrophages to suppress host immunity. Mechanistically, RING finger protein 114, a host E3 ligase, mediates K27-linked ubiquitination of Efb at lysine 71, which facilitates the recruitment of tumor necrosis factor receptor associated factor (TRAF) 3. The binding of Efb to TRAF3 disrupts the formation of the TRAF3/TRAF2/cIAP1 (cellular-inhibitor-of-apoptosis-1) complex, which mediates K48-ubiquitination of TRAF3 to promote degradation, resulting in suppression of the inflammatory signaling cascade. Additionally, the Efb K71R mutant loses the ability to inhibit inflammation and exhibits decreased pathogenicity. Therefore, our findings identify an unrecognized mechanism of Staphylococcus aureus to suppress host defense, which may be a promising target for developing effective anti-Staphylococcus aureus immunomodulators.

Staphylococcus aureus secrete numerous effectors to evade or inhibit the host immune response, yet the mechanism underlying the effectors ability to manipulate the signalling pathways of macrophages remain unclear. Authors utilise in vitro and in vivo models to explore the role of extracellular fibrinogen-binding protein (Efb) in immune response modulation and pathogenicity.

A profile of delafloxacin in the treatment of adults with community-acquired bacterial pneumonia

INTRODUCTION

Community-acquired bacterial pneumonia (CABP) is the most common infectious cause of hospital admission in adults, and poses a significant clinical and economic burden. At the same time, antimicrobial resistance is increasing worldwide with only a few new antibiotics developed in recent years. Delafloxacin is an anionic fluoroquinolone available in intravenous and oral formulations and with a broad spectrum of activity targeting Gram-positives, including methicillin-resistant Staphylococcus aureus (MRSA), gram-negative organisms, and atypical and anaerobic organisms. It also has a better adverse event profile compared to other fluoroquinolones.

AREAS COVERED

This article reviews the current epidemiology of CABP, etiologic agents and current resistance rates, current treatment guidelines, characteristics of delafloxacin (chemistry, microbiology, PK/PD), clinical efficacy and safety in pneumonia and other indications, and regulatory affairs.

EXPERT OPINION

Delafloxacin's susceptibility profile against respiratory pathogens, bioequivalent intravenous and oral formulations and favorable safety profile, support its use for the treatment of CABP. It could be useful as empirical treatment in countries with high rates of penicillin-resistant S. pneumoniae and in patients with suspected or documented pneumonia due to MRSA. In post-influenza staphylococcal bacterial pneumonia, MRSA could be also considered an important pathogen.

Staphylococcus aureus Community-acquired Pneumonia in Children After 13-Valent Pneumococcal Vaccination (2008-2018): Epidemiology, Clinical Characteristics and Outcomes

BACKGROUND

The epidemiology of community-acquired pneumonia (CAP) has changed, influenced by sociosanitary conditions and vaccination status. We aimed to analyze the recent epidemiology of bacterial CAP in hospitalized children in a setting with high pneumococcal vaccination coverage and to describe the clinical characteristics of pediatric Staphylococcus aureus CAP.

METHODS

Children <17 years old hospitalized from 2008 to 2018 with bacterial CAP in 5 tertiary hospitals in Spain were included. Cases with pneumococcal CAP were randomly selected as comparative group following a case-control ratio of 2:1 with S. aureus CAP.

RESULTS

A total of 313 bacterial CAP were diagnosed: Streptococcus pneumoniae CAP (n = 236, 75.4%), Streptococcus pyogenes CAP (n = 43, 13.7%) and S. aureus CAP (n = 34, 10.9%). Throughout the study period, the prevalence of S. pyogenes increased (annual percentage change: +16.1% [95% CI: 1.7-32.4], P = 0.031), S. pneumoniae decreased (annual percentage change: -4.4% [95 CI: -8.8 to 0.2], P = 0.057) and S. aureus remained stable. Nine isolates of S. aureus (26.5%) were methicillin-resistant. Seventeen cases (50%) with S. aureus CAP had some pulmonary complication and 21 (61.7%) required intensive care. S. pneumoniae CAP showed a trend toward higher prevalence of pulmonary complications compared with S. aureus CAP (69.1% vs. 50.0%, P = 0.060), including higher frequency of pulmonary necrosis (32.4% vs. 5.9%, P = 0.003).

CONCLUSIONS

The incidence of S. aureus CAP in children remained stable, whereas the prevalence of pneumococcal CAP decreased and S. pyogenes CAP increased. Patients with S. aureus presented a high frequency of severe outcomes, but a lower risk of pulmonary complications than patients with S. pneumoniae.

The Virulent Hypothetical Proteins: The Potential Drug Target Involved in Bacterial Pathogenesis

Abstract:

Hypothetical proteins (HPs) are non-predicted sequences that are identified only by open reading frames in sequenced genomes but their protein products remain uncharacterized by any experimental means. The genome of every species consists of HPs that are involved in various cellular processes and signaling pathways. Annotation of HPs is important as they play a key role in disease mechanisms, drug designing, vaccine production, antibiotic production, and host adaptation. In the case of bacteria, 25-50% of the genome comprises of HPs, which are involved in metabolic pathways and pathogenesis. The characterization of bacterial HPs helps to identify virulent proteins that are involved in pathogenesis. This can be done using in-silico studies, which provide sequence analogs, physiochemical properties, cellular or subcellular localization, structure and function validation, and protein-protein interactions. The most diverse types of virulent proteins are exotoxins, endotoxins, and adherent virulent factors that are encoded by virulent genes present on the chromosomal DNA of the bacteria. This review evaluates virulent HPs of pathogenic bacteria, such as Staphylococcus aureus, Chlamydia trachomatis, Fusobacterium nucleatum, and Yersinia pestis. The potential of these HPs as a drug target in bacteria-caused infectious diseases along with the mode of action and treatment approaches have been discussed.

Methicillin-resistant Staphylococcus aureus lung infection in coronavirus disease 2019: how common?

PURPOSE OF REVIEW

Some patients with coronavirus disease 2019 (COVID-19) may develop pulmonary bacterial coinfection or superinfection, that could unfavorably impact their prognosis.

RECENT FINDINGS

The exact burden of methicillin-resistant Staphylococcus aureus (MRSA) lung infection in peculiar populations such as patients with COVID-19 remains somewhat elusive, possibly because of wide heterogeneity in methods and endpoints across studies.

SUMMARY

There was important heterogeneity in the retrieved literature on the epidemiology of MRSA lung infection in patients with COVID-19, both when considering all other bacteria as the denominator (relative prevalence ranging from 2% to 29%) and when considering only S. aureus as the denominator (relative prevalence ranging from 11% to 65%). Overall, MRSA is among the most frequent causative agents of pulmonary infection in patients with COVID-19. Improving our ability to rapidly reach etiological diagnosis of bacterial lung infection in COVID-19 patients remains fundamental if we are to improve the rates of appropriate antibiotic therapy in patients with COVID-19 and concomitant/superimposed MRSA infection, at the same time avoiding antibiotic overuse in line with antimicrobial stewardship principles.

Antibiotic Decision-Making in the ICU

It is well established that Intensive Care Units (ICUs) are a focal point in antimicrobial consumption with a major influence on the ecological consequences of antibiotic use. With the high prevalence and mortality of infections in critically ill patients, and the clinical challenges of treating patients with septic shock, the impact of real life clinical decisions made by intensivists becomes more significant. Both under- and over-treatment with unnecessarily broad spectrum antibiotics can lead to detrimental outcomes. Even though substantial progress has been made in developing rapid diagnostic tests that can help guide antibiotic use, there is still a time window when clinicians must decide the empiric antibiotic treatment with insufficient clinical data. The continuous streams of data available in the ICU environment make antimicrobial optimization an ongoing challenge for clinicians but at the same time can serve as the input for sophisticated models. In this review, we summarize the evidence to help guide antibiotic decision-making in the ICU. We focus on 1) deciding IF: to start antibiotics, 2) choosing the spectrum of the empiric agents to use, and 3) de-escalating the chosen empiric antibiotics. We provide a perspective on the role of machine learning and artificial intelligence models for clinical decision support systems that can be incorporated seamlessly into clinical practice in order to improve the antibiotic selection process and, more importantly, current and future patients' outcomes.

Risk factors for community-onset pneumonia caused by drug-resistant pathogens: A prospective cohort study

INTRODUCTION

There is no consensual definition of risk factors for drug resistant pathogens (DRP) in community-onset pneumonia (COP). Healthcare-associated pneumonia criteria have been abandoned because they were found to have weak discriminative power. Our aim was to identify risk factors for DRP in COP.

METHODS

Prospective cohort study, conducted over a two years' period, in a community-based hospital, including all adult patients with COP criteria. Univariate and multivariate logistic regression modeling were performed to understand the association of risk factors (demographic, clinical and epidemiological) with COP by a DRP (PES: Pseudomonas aeruginosa, extended-spectrum ß-lactamase producing Enterobacteriaceae, Methicillin-resistant Staphylococcus aureus; and other non-fermenting gram-negative bacteria, namely Acinetobacter baumannii).

RESULTS

A total of 660 cases of COP were included, with a mean (±SD) age of 74±15 years and 58.9% of males. Microbiological documentation was possible in 32.6% of the cases. There were 197 cases selected for further analysis, of which 37 were cases of PES. The multivariate logistic regression model retained antibiotic use in the previous 90 days (adjusted OR=4.411, 95%CI [1.745-11.148]) and being bed-ridden (adjusted OR=5.492, 95%CI [2.121-14.222]), adjusted for Charlson's Index, CURB 65 and provenience from a long-term care facility. The area under the ROC curve for this model was 0.832, 95%CI [0.756-0.908], higher than the application of the HCAP criteria (AUROC = 0.676, 95%CI [0.582-0.770]).

CONCLUSION

In this study, antibiotic use in the previous 90 days and being bed-ridden were independently associated with COP caused by DRP, after adjustment for Charlson's Index, CURB 65 and provenience from a long-term care facility.

Current pharmacotherapy for methicillin-resistant Staphylococcus aureus (MRSA) pneumonia

INTRODUCTION

Currently, several antibiotics are active against methicillin-resistant Staphylococcus aureus (MRSA) and can be used for the treatment of pneumonia. They show great variability in terms of antibiotic class, indication, pharmacodynamic/pharmacokinetic properties, type of available formulations, spectrum of activity against bacteria other than MRSA, and toxicity profile.

AREAS COVERED

In this narrative review, the authors discuss the characteristics of currently available agents for the treatment of MRSA pneumonia.

EXPERT OPINION

The availability of different agents with anti-MRSA activity, and approved for the treatment of pneumonia can allow a personalized approach for any given patient based on the severity of the disease, the setting of occurrence, the patient's baseline risk of toxicity and drug interactions, and the possibility of oral therapy whenever early discharge or outpatient treatment are possible. Although some gray areas still remain, like the lack of high certainty evidence on the efficacy of some old agents and on the precise role of companion agents with toxin inhibitory activity in the case of necrotizing pneumonia, the frequent availability of different treatment choices, each with peculiar characteristics, is already allowing an important step toward a precision medicine approach for the treatment of MRSA pneumonia.

Guía de práctica clínica para el manejo de la neumonía adquirida en la comunidad

La neumonía sigue siendo una de las principales causas de consulta y de hospitalización a la que, además de su un alto impacto en términos de morbilidad y mortalidad, se suma la actual problemática de resistencia a los antimicrobianos, por lo que establecer directrices que permitan su adecuado diagnóstico y tratamiento es de gran importancia para obtener mejores desenlaces clínicos y promover un uso racional de antibióticos en estos pacientes. La presente guía de práctica clínica (GPC) contiene recomendaciones basadas en la evidencia para el diagnóstico y tratamiento de la neumonía adquirida en la comunidad en adultos, las cuales fueron realizadas mediante el proceso de adaptación de GPC basadas en la evidencia para el contexto colombiano.

Invasive pneumococcal disease burden in hospitalized adults in Bogota, Colombia

Background

The incidence of invasive pneumococcal disease (IPD) varies depending on a number of factors, including vaccine uptake, in both children and adults, the geographic location, and local serotype prevalence. There are limited data about the burden of Streptococcus pneumoniae (Spn), serotype distribution, and clinical characteristics of adults hospitalized due to IPD in Colombia. The objectives of this study included assessment of Spn serotype distribution, clinical characteristics, mortality, ICU admission, and the need for mechanical ventilation.

Methods

This was an observational, retrospective, a citywide study conducted between 2012 and 2019 in Bogotá, Colombia. We analyzed reported positive cases of IPD from 55 hospitals in a governmental pneumococcal surveillance program. Pneumococcal strains were isolated in each hospital and typified in a centralized laboratory. This is a descriptive study stratified by age and subtypes of IPD obtained through the analysis of medical records.

Results

A total of 310 patients with IPD were included, of whom 45.5% were female. The leading cause of IPD was pneumonia (60%, 186/310), followed by meningitis. The most frequent serotypes isolated were 19A (13.87%, 43/310) and 3 (11.94%, 37/310). The overall hospital mortality rate was 30.3% (94/310). Moreover, 52.6% (163/310 patients) were admitted to the ICU, 45.5% (141/310) required invasive mechanical ventilation and 5.1% (16/310) non-invasive mechanical ventilation.

Conclusion

Pneumococcal pneumonia is the most prevalent cause of IPD, with serotypes 19A and 3 being the leading cause of IPD in Colombian adults. Mortality due to IPD in adults continues to be very high.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-06769-2.

Community-acquired pneumonia

Community-acquired pneumonia is not usually considered a high-priority problem by the public, although it is responsible for substantial mortality, with a third of patients dying within 1 year after being discharged from hospital for pneumoniae. Although up to 18% of patients with community-acquired pneumonia who were hospitalised (admitted to hospital and treated there) have at least one risk factor for immunosuppression worldwide, strong evidence on community-acquired pneumonia management in this population is scarce. Several features of clinical management for community-acquired pneumonia should be addressed to reduce mortality, morbidity, and complications related to community-acquired pneumonia in patients who are immunocompetent and patients who are immunocompromised. These features include rapid diagnosis, microbiological investigation, prevention and management of complications (eg, respiratory failure, sepsis, and multiorgan failure), empirical antibiotic therapy in accordance with patient's risk factors and local microbiological epidemiology, individualised antibiotic therapy according to microbiological data, appropriate outcomes for therapeutic switch from parenteral to oral antibiotics, discharge planning, and long-term follow-up. This Seminar offers an updated view on community-acquired pneumonia in adults, with suggestions for clinical and translational research.

Tenascin C Has a Modest Protective Effect on Acute Lung Pathology during Methicillin-Resistant Staphylococcus aureus-Induced Pneumonia in Mice

Tenascin C (TNC) is an extracellular matrix protein with immunomodulatory properties that plays a major role during tissue injury and repair. TNC levels are increased in patients with pneumonia and pneumosepsis, and they are associated with worse outcomes. Methicillin-resistant Staphylococcus aureus (MRSA) is a Gram-positive bacterium that is a major causative pathogen in nosocomial pneumonia and a rising cause of community-acquired pneumonia. To study the role of TNC during MRSA-induced pneumonia, TNC sufficient (TNC+/+) and TNC-deficient (TNC-/-) mice were infected with MRSA via the airways and euthanized after 6, 24, and 48 h for analysis. Pulmonary transcription of TNC peaked at 6 h, while immunohistochemistry revealed higher protein levels at later time points. Although TNC deficiency was not associated with changes in bacterial clearance, TNC-/- mice showed increased levels of TNF-α and IL-6 in bronchoalveolar lavage fluid during the acute phase of infection when compared with TNC+/+ mice. In addition, TNC-/- mice showed more severe pulmonary pathology at 6, but not at 24 or 48 h, after infection. Together, these data suggest that TNC plays a moderate protective role against tissue pathology during the acute inflammatory phase, but not during the bacterial clearance phase, of MRSA-induced pneumonia. These results argue against an important role of TNC on disease outcome during MRSA-induced pneumonia. IMPORTANCE Recently, the immunomodulatory properties of TNC have drawn substantial interest. However, to date most studies made use of sterile models of inflammation. In this study, we examine the pathobiology of MRSA-induced pneumonia in a model of TNC-sufficient and TNC-deficient mice. We have studied the immune response and tissue pathology both during the initial insult and also during the resolution phase. We demonstrate that MRSA-induced pneumonia upregulates pulmonary TNC expression at the mRNA and protein levels. However, the immunomodulatory role of TNC during bacterial pneumonia is distinct from models of sterile inflammation, indicating that the function of TNC is context dependent. Contrary to previous descriptions of TNC as a proinflammatory mediator, TNC-deficient mice seem to suffer from enhanced tissue pathology during the acute phase of infection. Nonetheless, besides its role during the acute phase response, TNC does not seem to play a major role in disease outcome during MRSA-induced pneumonia.

Active Surveillance, Drug Resistance, and Genotypic Profiling of Staphylococcus aureus Among School-Age Children in China

Methicillin-susceptible (MSSA) and methicillin-resistant Staphylococcus aureus (MRSA) nasal colonization predisposes individuals for endogenous infections and is a major threat to children. Recently, oxacillin/cefoxitin-susceptible mecA-positive S. aureus (OS-MRSA) has been reported worldwide. Herein, a prospective, cross-sectional study was conducted across five schools, representing three educational stages, in Guangzhou, China. Nasal swabs from 2,375 students were cultured for S. aureus and all isolates were subjected to antibiotic susceptibility testing phenotypically and confirmed by femB and mecA genetic detection; all the isolates were classified as MSSA, MRSA, or OS-MRSA. All strains were also analyzed by multi-locus sequence typing. Among the 2,375 swabs, S. aureus was detected in 744 children (31.3%, 95% CI: 25.9–36.7%), of whom 72 had MRSA (3.0%, 95% CI: 0.6–5.4%) and 4 had OS-MRSA (0.2%, 95% CI: 0.1–0.3%), of which an oxacillin- and cefoxitin-susceptible MRSA strain was identified. The prevalence of S. aureus and MRSA was higher in younger children. The highest percentage of drug resistance of the S. aureus isolates (n = 744) was to penicillin (85.5%), followed by erythromycin (43.3%) and clidamycin (41.0%). The most prevalent sequence types (STs) were ST30, ST45, and ST188 in MSSA, accounting for 38.7% of the total isolates, whereas ST45, ST59, and ST338 accounted for 74.6% of the MRSA isolates and ST338 accounted for 50.0% of the OS-MRSA isolates. The MRSA and OS-MRSA isolates (n = 76) were grouped into three clades and one singleton, with clonal complex (CC) 45 as the most predominant linkage. The top nine multi-locus sequence typing-based CCs (CC30, CC45, CC5, CC1, CC15, CC944, CC398, CC59, CC7) represented 86.7% of all S. aureus isolates. All CC30 isolates were resistant to erythromycin and clidamycin, and almost all these isolates were also resistant to penicillin (99.2%). The CC45 and CC59 isolates exhibited high resistance rates to oxacillin at 31.5 and 59.0%, respectively. This study provides updated data valuable for designing effective control strategies to mitigate the burden of disease and to improve the adequacy of empirical antimicrobial treatments for potentially harmful infections.

Initial antimicrobial management of sepsis

Sepsis is a common consequence of infection, associated with a mortality rate > 25%. Although community-acquired sepsis is more common, hospital-acquired infection is more lethal. The most common site of infection is the lung, followed by abdominal infection, catheter-associated blood steam infection and urinary tract infection. Gram-negative sepsis is more common than gram-positive infection, but sepsis can also be due to fungal and viral pathogens. To reduce mortality, it is necessary to give immediate, empiric, broad-spectrum therapy to those with severe sepsis and/or shock, but this approach can drive antimicrobial overuse and resistance and should be accompanied by a commitment to de-escalation and antimicrobial stewardship. Biomarkers such a procalcitonin can provide decision support for antibiotic use, and may identify patients with a low likelihood of infection, and in some settings, can guide duration of antibiotic therapy. Sepsis can involve drug-resistant pathogens, and this often necessitates consideration of newer antimicrobial agents.

Validation of a Prediction Score for Drug-Resistant Microorganisms in Community-acquired Pneumonia

Rationale: Recommended initial empiric antimicrobial treatment covers the most common bacterial pathogens; however, community-acquired pneumonia (CAP) may be caused by microorganisms not targeted by this treatment. Developed in 2015, the PES (Pseudomonas aeruginosa, extended-spectrum β-lactamase-producing Enterobacteriaceae, and methicillin-resistant Staphylococcus aureus) score was developed in 2015 to predict the microbiological etiology of CAP caused by PES microorganisms.Objective: To validate the usefulness of the PES score for predicting PES microorganisms in two cohorts of patients with CAP from Valencia and Mataró.Methods: We analyzed two prospective observational cohorts of patients with CAP from Valencia and Mataró. Patients in the Mataró cohort were all admitted to an intensive care unit (ICU).Results: Of the 1,024 patients in the Valencia cohort, 505 (51%) had a microbiological etiology and 31 (6%) had a PES microorganism isolated. The area under the receiver operating characteristic curve was 0.81 (95% confidence interval [95% CI], 0.74-0.88). For a PES score ≥5, sensitivity, specificity, the negative and positive predictive values as well as the negative and positive likelihood ratios were 72%, 74%, 98%, 14%, 0.38, and 2.75, respectively. Of the 299 patients in the Mataró cohort, 213 (71%) had a microbiological etiology and 11 (5%) had a PES microorganism isolated. The area under the receiver operating characteristic curve was 0.73 (95% CI 0.61-0.86). For a PES score ≥ 5, sensitivity, specificity, the negative and positive predictive values, and the negative and positive likelihood ratios were 36%, 83%, 96%, 11%, 0.77, and 2.09, respectively. The best cutoff for patients admitted to the ICU was 4 points, which improved sensitivity to 86%. The hypothetical application of the PES score showed high rates of overtreatment in both cohorts (26% and 35%, respectively) and similar rates of undertreatment.Conclusions: The PES score showed good accuracy in predicting the risk for microorganisms that required different empirical therapy; however, its use as a single strategy for detecting noncore pathogens could lead to high rates of overtreatment. Given its high negative predictive value, the PES score may be used as a first step of a wider strategy that includes subsequent advanced diagnostic tests.