miR-486-5p predicted adverse outcomes of SCAP and regulated K. pneumonia infection via FOXO1

PURPOSE

Severe community-acquired pneumonia (SCAP) is a common respiratory system disease with rapid development and high mortality. Exploring effective biomarkers for early detection and development prediction of SCAP is of urgent need. The function of miR-486-5p in SCAP diagnosis and prognosis was evaluated to identify a promising biomarker for SCAP.

PATIENTS AND METHODS

The serum miR-486-5p in 83 patients with SCAP, 52 healthy individuals, and 68 patients with mild CAP (MCAP) patients were analyzed by PCR. ROC analysis estimated miR-486-5p in screening SCAP, and the Kaplan-Meier and Cox regression analyses evaluated the predictive value of miR-486-5p. The risk factors for MCAP patients developing SCAP were assessed by logistic analysis. The alveolar epithelial cell was treated with Klebsiella pneumonia to mimic the occurrence of SCAP. The targeting mechanism underlying miR-486-5p was evaluated by luciferase reporter assay.

RESULTS

Upregulated serum miR-486-5p screened SCAP from healthy individuals and MCAP patients with high sensitivity and specificity. Increasing serum miR-486-5p predicted the poor outcomes of SCAP and served as a risk factor for MCAP developing into SCAP. K. pneumonia induced suppressed proliferation, significant inflammation and oxidative stress in alveolar epithelial cells, and silencing miR-486-5p attenuated it. miR-486-5p negatively regulated FOXO1, and the knockdown of FOXO1 reversed the effect of miR-486-5p in K. pneumonia-treated alveolar epithelial cells.

CONCLUSION

miR-486-5p acted as a biomarker for the screening and monitoring of SCAP and predicting the malignancy of MCAP. Silencing miR-486-5p alleviated inflammation and oxidative stress induced by K. pneumonia via negatively modulating FOXO1.

Results from the Survey of Antibiotic Resistance (SOAR) 2002-09 in Turkey

OBJECTIVES

To investigate changes in antibiotic susceptibility of Streptococcus pneumoniae and Haemophilus influenzae from the Survey of Antibiotic Resistance (SOAR) in community-acquired respiratory tract infections (CA-RTIs) between 2002 and 2009 in Turkey.

METHODS

Previously published SOAR data were used for this analysis. MICs were determined using Etest(®) gradient strips or disc diffusion. Susceptibility against a range of antimicrobial agents was assessed using CLSI breakpoints.

RESULTS

A total of 900 S. pneumoniae isolates were analysed: 2002-03 (n = 75), 2004-05 (n = 301) and 2007-09 (n = 524). Four antibiotics were tested consistently throughout and three showed a statistically significant decrease in susceptibility (P < 0.0001): penicillin (74.7% susceptible in 2002-03; 67.8% in 2004-05; and 47.2% in 2007-09); cefaclor (85.3% in 2002-03; 78.7% in 2004-05; and 53.5% in 2007-09) and clarithromycin (85.3% in 2002-03; 82.7% in 2004-05; and 61.9% in 2007-09). Susceptibility to amoxicillin/clavulanic acid did not significantly change (100% in 2002-03; 98.7% in 2004-05; and 97.7% in 2007-09). A total of 930 H. influenzae isolates were analysed: 2002-03 (n = 133), 2004-05 (n = 379) and 2007-09 (n = 418). Four antibiotics were also consistently tested: ampicillin, amoxicillin/clavulanic acid, clarithromycin and cefaclor. All showed >90% susceptibility, but only cefaclor susceptibility significantly reduced (P < 0.0001) over time (99.2% in 2002-03; 96.3% in 2004-05; and 90.4% in 2007-09).

CONCLUSIONS

In S. pneumoniae from Turkey, there has been a clear statistically significant reduction in susceptibility to key antibiotics since 2002, but not to amoxicillin/clavulanic acid (or amoxicillin). However, susceptibility in H. influenzae remained stable. Continued surveillance is required to monitor future changes in antibiotic susceptibility for CA-RTI bacteria.

Mouse Model of Respiratory Tract Infection Induced by Waddlia chondrophila

Waddlia chondrophila, an obligate intracellular bacterium belonging to the Chlamydiales order, is considered as an emerging pathogen. Some clinical studies highlighted a possible role of W. chondrophila in bronchiolitis, pneumonia and miscarriage. This pathogenic potential is further supported by the ability of W. chondrophila to infect and replicate within human pneumocytes, macrophages and endometrial cells. Considering that W. chondrophila might be a causative agent of respiratory tract infection, we developed a mouse model of respiratory tract infection to get insight into the pathogenesis of W. chondrophila. Following intranasal inoculation of 2 x 10⁸W. chondrophila, mice lost up to 40% of their body weight, and succumbed rapidly from infection with a death rate reaching 50% at day 4 post-inoculation. Bacterial loads, estimated by qPCR, increased from day 0 to day 3 post-infection and decreased thereafter in surviving mice. Bacterial growth was confirmed by detecting dividing bacteria using electron microscopy, and living bacteria were isolated from lungs 14 days post-infection. Immunohistochemistry and histopathology of infected lungs revealed the presence of bacteria associated with pneumonia characterized by an important multifocal inflammation. The high inflammatory score in the lungs was associated with the presence of pro-inflammatory cytokines in both serum and lungs at day 3 post-infection. This animal model supports the role of W. chondrophila as an agent of respiratory tract infection, and will help understanding the pathogenesis of this strict intracellular bacterium.

Staphylococcus aureus infections: epidemiology, pathophysiology, clinical manifestations, and management

Staphylococcus aureus is a major human pathogen that causes a wide range of clinical infections. It is a leading cause of bacteremia and infective endocarditis as well as osteoarticular, skin and soft tissue, pleuropulmonary, and device-related infections. This review comprehensively covers the epidemiology, pathophysiology, clinical manifestations, and management of each of these clinical entities. The past 2 decades have witnessed two clear shifts in the epidemiology of S. aureus infections: first, a growing number of health care-associated infections, particularly seen in infective endocarditis and prosthetic device infections, and second, an epidemic of community-associated skin and soft tissue infections driven by strains with certain virulence factors and resistance to β-lactam antibiotics. In reviewing the literature to support management strategies for these clinical manifestations, we also highlight the paucity of high-quality evidence for many key clinical questions.

Nonmolecular methods for the diagnosis of respiratory fungal infections

Diagnosis of invasive fungal pneumonias by conventional culture methods is difficult to assess and often delayed. Nonmolecular fungal markers have emerged as an important adjunctive tool to support their diagnosis in combination with other clinical, radiologic, and microbiological criteria of invasive fungal diseases. Concerns about the sensitivity and specificity of some tests in different patient populations should lead to warnings about their widespread use. None can identify the emerging and particularly deadly fungal pathogens responsible for mucormycosis. The role of nonmolecular fungal markers should be better defined in combination with other microbiological and radiologic tools in preemptive antifungal strategies.

The changing microbiologic epidemiology of community-acquired pneumonia

Community-acquired pneumonia (CAP) is a common infectious disease in the United States and the incidence continues to grow as the aging population increases. Overall, in-hospital patient mortality rates have been reported to be as high as 18%. Management of patients with CAP has been challenged by the evolution of resistant pathogens (particularly Streptococcus pneumoniae and Staphylococcus aureus) that have reduced susceptibility to recommended standard antimicrobial agents. Streptococcus pneumoniae continues to be the most frequently identified pathogen in CAP and recently, S. aureus has been found to be the second most often identified pathogen. Data from the SENTRY Antimicrobial Surveillance Program has shown declining susceptibility of pneumococci to penicillin, amoxicillin/clavulanate, and ceftriaxone from 1998 through 2011. In the Assessing Worldwide Resistance Evaluation (AWARE) surveillance program, > 50% of all S. aureus isolates from patient bloodstream infections, skin and skin structure infections, and pneumonia were methicillin-resistant. Stratifying risk factors to identify patients at risk for community-acquired multidrug-resistant pathogens should be considered when selecting therapy. Differences in microbiology and outcomes have been noted in patients presenting from the community with recent exposure to the health care system (eg, nursing home residents, patients with a recent hospital admission). These patients are at an increased risk of an infection caused by a multidrug-resistant pathogen. Understanding a patient's risk for drug-resistant pathogens will allow the physician to choose an appropriate empiric treatment regimen to optimize clinical outcomes.

Microbiological diagnosis and antibiotic therapy in patients with community-acquired pneumonia and acute COPD exacerbation in daily clinical practice: comparison to current guidelines

BACKGROUND

The aim of this secondary analysis was to evaluate current microbiological approaches, microbiology, and antibiotic therapy in patients with community-acquired pneumonia (CAP) and acute exacerbation of chronic obstructive pulmonary disease (AECOPD) in clinical practice and to compare them with current international guidelines.

METHODS

A total of 362 patients with suspected CAP were enrolled in 14 European centers in a prospective multicenter study.

RESULTS

A total of 279 inpatients (CAP, n = 222; AECOPD, n = 57) were evaluated. A total of 83 (37 %) CAP patients and 25 (44 %) AECOPD patients did not undergo any microbiological tests. In patients with CAP/AECOPD, blood culture was performed in 109 (49 %)/16 (28.1 %), urinary antigen tests for Legionella pneumophila in 67 (30 %)/9 (16 %), and sputum investigation in 55 (25 %)/17 (30 %), respectively. The most frequent pathogens in CAP were Streptococcus pneumoniae, Mycoplasma pneumoniae, Chlamydia pneumoniae, L. pneumophila, Staphylococcus aureus, and Enterobacter cloacae; in AECOPD they were Escherichia coli, Haemophilus haemolyticus, Haemophilus influenzae, and Moraxella catarrhalis. All CAP patients (mean = 11.1 days) and 35 (61.4 %) of AECOPD patients (mean = 8.9 days) received antibiotics. CAP patients were given mostly aminopenicillin with β-lactamase inhibitors and AECOPD patients were given mostly cephalosporins.

CONCLUSIONS

Pathogens isolated in CAP and AECOPD and the antibiotic therapy used are in good accordance with the guidelines. Blood culture, recommended for all CAP patients, was performed in only 50 % of the cases and antibiotic therapy lasted longer than the suggested 5-7 days. Therefore, international guidelines regarding performance of blood culture and duration of antibiotic therapy should be adopted more often. This duration was independent of the number of isolated pathogens and number of symptoms on admission. Therefore, the question arises as to whether microbiological data are necessary only for patients who are resistant to initial therapy.

High-dose levofloxacin in community-acquired pneumonia: a randomized, open-label study

BACKGROUND

The conventional treatment for community-acquired pneumonia (CAP) involves combination therapy consisting of a β-lactam penicillin or a cephalosporin with a macrolide. Alternatively, high-dose levofloxacin treatment has been used as single-agent therapy for treating CAP, covering atypical pathogens.

OBJECTIVE

This study compared the clinical efficacy and safety of high-dose levofloxacin with combined ceftriaxone and azithromycin for the treatment of CAP.

PATIENTS AND METHODS

This phase IV, prospective, randomized, open-label trial enrolled patients admitted to a tertiary referral hospital for CAP treatment from 2010 to 2011. Hospital admission was decided based on clinical judgement and the pneumonia severity index. Forty subjects were enrolled and assigned to two treatment arms using a random numbers table. The 20 subjects in the experimental group were given levofloxacin 750 mg intravenously once daily, followed by the same dose of oral levofloxacin at discharge when clinically improved and the 20 subjects in the control group were given ceftriaxone 2.0 g intravenously once daily plus oral azithromycin 500 mg for 3 consecutive days, followed by oral cefpodoxime 200 mg per day at discharge after clinical improvement. The primary outcome was the clinical success rate. Secondary outcomes were the microbiological success rate and adverse events during the study.

RESULTS

Of the 40 subjects enrolled, 36 completed the study: 17 in the experimental group and 19 in the control group. The groups did not differ in terms of demographic factors or clinical findings at baseline. The clinical success rate (cured + improved) was 94% in the experimental (levofloxacin) group and 84% in the control group (p > 0.05). The microbiological success rate and overall adverse events were also similar in both groups.

CONCLUSION

Single-agent, high-dose levofloxacin treatment exhibited excellent clinical and microbiological efficacy with a safety profile comparable to that of ceftriaxone plus azithromycin therapy. Large-scale clinical trials are required to verify these results.

CLINICAL TRIAL REGISTRATION

WHO International Clinical Trials Registry: KCT0000374; Daiichi-Sankyo Korea study code: T11-13-V1.

AWARE Ceftaroline Surveillance Program (2008-2010): trends in resistance patterns among Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis in the United States

Ceftaroline fosamil, the prodrug form of the active metabolite ceftaroline, is a new broad-spectrum parenteral cephalosporin with antibacterial activity against the prevalent respiratory pathogens Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, and Staphylococcus aureus. Bacterial resistance surveillance (5330 isolates) was conducted in the United States between 2008 and 2010 to assess the in vitro activity of ceftaroline and comparator antibacterial agents against invasive respiratory isolates of S. pneumoniae (3329 isolates), H. influenzae (1545 isolates), and M. catarrhalis (456 isolates). All organisms were cultured from patient infections in 71 US hospital laboratories and were submitted to a central reference monitor for broth microdilution testing by Clinical and Laboratory Standards Institute reference methods. Against S. pneumoniae, ceftaroline inhibited 98.7% of strains at the susceptible breakpoint of ≤ 0.25 µg/mL (50% minimum inhibitory concentration [MIC(50)], 0.01 µg/mL; 90% MIC [MIC(90)], 0.12 µg/mL) and was 16-fold more active than ceftriaxone (MIC(90), 2 µg/mL). Among 70 ceftriaxone-resistant pneumococcal isolates, all were inhibited by ≤ 0.5 µg/mL of ceftaroline. Haemophilus influenzae (MIC(50), ≤ 0.008 µg/mL; MIC(90), 0.015 µg/mL) and M. catarrhalis (MIC(50), 0.06 µg/mL; MIC(90), 0.12 µg/mL) were very susceptible to ceftaroline regardless of β-lactamase production. Whereas the high-level of activity of ceftaroline was maintained against S. pneumoniae and H. influenzae from 2008 through 2010, increased rates of nonsusceptibility were observed for amoxicillin/clavulanate, erythromycin, and levofloxacin among S. pneumoniae and for trimethoprim/sulfamethoxazole and azithromycin among H. influenzae. In summary, ceftaroline resistance surveillance (Assessing Worldwide Antimicrobial Resistance Evaluation [AWARE] Program) in the United States (2008-2010) documented in vitro sustained potency and spectrum against Gram-positive and Gram-negative pathogens known to cause community-acquired bacterial pneumonia.

High-dose levofloxacin in community-acquired pneumonia: a randomized, open-label study

BACKGROUND

The conventional treatment for community-acquired pneumonia (CAP) involves combination therapy consisting of a β-lactam penicillin or a cephalosporin with a macrolide. Alternatively, high-dose levofloxacin treatment has been used as single-agent therapy for treating CAP, covering atypical pathogens.

OBJECTIVE

This study compared the clinical efficacy and safety of high-dose levofloxacin with combined ceftriaxone and azithromycin for the treatment of CAP.

PATIENTS AND METHODS

This phase IV, prospective, randomized, open-label trial enrolled patients admitted to a tertiary referral hospital for CAP treatment from 2010 to 2011. Hospital admission was decided based on clinical judgement and the pneumonia severity index. Forty subjects were enrolled and assigned to two treatment arms using a random numbers table. The 20 subjects in the experimental group were given levofloxacin 750 mg intravenously once daily, followed by the same dose of oral levofloxacin at discharge when clinically improved and the 20 subjects in the control group were given ceftriaxone 2.0 g intravenously once daily plus oral azithromycin 500 mg for 3 consecutive days, followed by oral cefpodoxime 200 mg per day at discharge after clinical improvement. The primary outcome was the clinical success rate. Secondary outcomes were the microbiological success rate and adverse events during the study.

RESULTS

Of the 40 subjects enrolled, 36 completed the study: 17 in the experimental group and 19 in the control group. The groups did not differ in terms of demographic factors or clinical findings at baseline. The clinical success rate (cured + improved) was 94% in the experimental (levofloxacin) group and 84% in the control group (p > 0.05). The microbiological success rate and overall adverse events were also similar in both groups.

CONCLUSION

Single-agent, high-dose levofloxacin treatment exhibited excellent clinical and microbiological efficacy with a safety profile comparable to that of ceftriaxone plus azithromycin therapy. Large-scale clinical trials are required to verify these results.

CLINICAL TRIAL REGISTRATION

WHO International Clinical Trials Registry: KCT0000374; Daiichi-Sankyo Korea study code: T11-13-V1.

Comparative ceftaroline activity tested against pathogens associated with community-acquired pneumonia: results from an international surveillance study

OBJECTIVES

To document the spectrum of activity of ceftaroline, the active form of the prodrug, ceftaroline fosamil, a new cephalosporin with anti-methicillin-resistant staphylococcal activity, against a surveillance collection of clinical isolates obtained from the USA and Europe during 2008-09.

METHODS

A selected group of species associated with community-acquired pneumonia (CAP; 6496 of 17 326 monitored strains) were tested for susceptibility in a central laboratory using CLSI broth microdilution methods. Organisms were sampled from 55 medical centres, 27 in the USA and 28 (12 countries) in Europe. Ceftaroline and comparator agents were tested and interpretations of MIC endpoints made by applying current CLSI (2010) and EUCAST (2010) breakpoint criteria.

RESULTS

Against 1340 Streptococcus pneumoniae, ceftaroline inhibited all isolates at ≤0.5 mg/L (MIC(50/90), ≤0.008/0.12 mg/L) and was 8-fold more active than ceftriaxone (MIC(90), 1 mg/L; only 79.2% coverage at EUCAST breakpoint). Haemophilus influenzae (n = 584; MIC(50/90), ≤0.008/0.015 mg/L), Moraxella catarrhalis (n = 377; MIC(50/90), 0.03-0.06/0.12 mg/L) and Staphylococcus aureus (n = 590; MIC(50/90), 0.5/1 mg/L) were very susceptible to ceftaroline, regardless of β-lactamase production or multidrug resistance (MDR) patterns. The potency of ceftaroline against three species of Enterobacteriaceae (Escherichia coli, Klebsiella pneumoniae and Enterobacter cloacae) was similar to that of ceftriaxone, ceftazidime and piperacillin/tazobactam. Only modest differences in rates of ceftaroline susceptibility (breakpoint ≤2 mg/L) were noted with extended-spectrum β-lactamase-negative Enterobacteriaceae strains between the USA and Europe (97.9% versus 97.0% for E. coli). Ceftaroline, like ceftriaxone, was not active against ceftazidime-resistant E. coli (10.2%-26.2% susceptible at ≤2 mg/L) or K. pneumoniae (5.3%-11.2%).

CONCLUSIONS

The ceftaroline surveillance for 2008-09 (USA and Europe) documented low MIC(50/90) values for S. aureus isolates at 0.5/1 and 0.25/1 mg/L, respectively. More importantly, ceftaroline MIC(90) results for S. pneumoniae (0.12 mg/L), H. influenzae (0.015 mg/L) and M. catarrhalis (0.12 mg/L) were very low, all MICs being ≤0.5 mg/L. Ceftaroline exhibited promising high potency and wide coverage against Gram-positive and -negative pathogens known to cause CAP, especially isolates of MDR pneumococci and methicillin-resistant S. aureus.

Amoebal pathogens as emerging causal agents of pneumonia

Despite using modern microbiological diagnostic approaches, the aetiological agents of pneumonia remain unidentified in about 50% of cases. Some bacteria that grow poorly or not at all in axenic media used in routine clinical bacteriology laboratory but which can develop inside amoebae may be the agents of these lower respiratory tract infections (RTIs) of unexplained aetiology. Such amoebae-resisting bacteria, which coevolved with amoebae to resist their microbicidal machinery, may have developed virulence traits that help them survive within human macrophages, i.e. the first line of innate immune defence in the lung. We review here the current evidence for the emerging pathogenic role of various amoebae-resisting microorganisms as agents of RTIs in humans. Specifically, we discuss the emerging pathogenic roles of Legionella-like amoebal pathogens, novel Chlamydiae (Parachlamydia acanthamoebae, Simkania negevensis), waterborne mycobacteria and Bradyrhizobiaceae (Bosea and Afipia spp.).

Spectrum of microbial etiology of community-acquired pneumonia in hospitalized patients: implications for selection of the population for enrollment in clinical trials

The title of this article implies that knowledge of the etiological pathogen may be useful in selection of patients for clinical trials for community-acquired pneumonia (CAP). However, this remains to be seen. The clinical course of a patient with CAP admitted to the hospital but not to the intensive care unit depends on a number of variables, including the patient, the pathogen, and the hospital itself. The site-of-care decision can be based on 1 of 2 prediction rules. Neither of these rules, however, correlates with the etiology of CAP, and it is not clear whether they can be used to stratify patients according to prognostic factors. A pathogen may be found in only approximately one-third of hospitalized patients with CAP overall. An etiological diagnosis is more likely to be made for patients with CAP who are hospitalized in the intensive care unit (39%) than for those hospitalized in other wards (20%). The issue of randomization to treatment regimens and possible approaches to randomization are discussed. It seems clear, however, that randomization would have to take place immediately after entry of the patient into the study. The possibility of using risks for specific pathogens or risks for antimicrobial resistance is also addressed. However, there are no data to support the use of such risks as prognostic factors in CAP. The best approach for noninferiority trials involving hospitalized patients with CAP is to randomize patients who meet the inclusion criteria and to stratify them by hospital site, with block randomization within each site. Stratification by site takes into account local epidemiology and can balance differences in unmeasured confounders among sites.

Clinical trial design and consequences for drug development for community-acquired pneumonia: an industry perspective

Antibiotic development has decreased significantly, in part because of recent changes in regulatory requirements in the United States. These changes both decrease the probability of technical and regulatory success for a new antibiotic for which marketing approval is sought and motivate the pharmaceutical industry to focus its research efforts on other therapeutic areas. There is a growing, unmet clinical need for new antibiotics, because of bacterial resistance to approved drugs; however, there are few candidates in development, especially new oral agents for treatment of community-acquired respiratory infections. The answers to important questions about the benefit of antibacterial treatment for community-acquired pneumonia and the publication of clear guidance for future clinical studies will support future investments. We discuss the underlying issues and offer some alternative strategies to enable improvements in clinical trial design for community-acquired pneumonia.