Metabolic profiles in community-acquired pneumonia: developing assessment tools for disease severity.

BACKGROUND: This study aimed to determine whether community-acquired pneumonia (CAP) had a metabolic profile and whether this profile can be used for disease severity assessment. METHODS: A total of 175 individuals including 119 CAP patients and 56 controls were enrolled and divided into two cohorts. Serum samples from a discovery cohort (n = 102, including 38 non-severe CAP, 30 severe CAP, and 34 age and sex-matched controls) were determined by untargeted ultra-high-performance liquid chromatography with tandem mass spectrometry (LC-MS/MS)-based metabolomics. Selected differential metabolites between CAP patients versus controls, and between the severe CAP group versus non-severe CAP group, were confirmed by targeted mass spectrometry assays in a validation cohort (n = 73, including 32 non-severe CAP, 19 severe CAP and 22 controls). Pearson's correlation analysis was performed to assess relationships between the identified metabolites and clinical severity of CAP. The area under the curve (AUC), sensitivity and specificity of the metabolites for predicting the severity of CAP were also investigated. RESULTS: The metabolic signature was markedly different between CAP patients and controls. Fifteen metabolites were found to be significantly dysregulated in CAP patients, which were mainly mapped to the metabolic pathways of sphingolipid, arginine, pyruvate and inositol phosphate. The alternation trends of five metabolites among the three groups including sphinganine, p-Cresol sulfate, dehydroepiandrosterone sulfate (DHEA-S), lactate and L-arginine in the validation cohort were consistent with those in the discovery cohort. Significantly lower concentrations of sphinganine, p-Cresol sulfate and DHEA-S were observed in CAP patients than in controls (p < 0.05). Serum lactate and sphinganine levels were positively correlated with confusion, urea level, respiratory rate, blood pressure, and age > 65 years (CURB-65), pneumonia severity index (PSI) and Acute Physiology and Chronic Health Evaluation II (APACHE II) scores, while DHEA-S inversely correlated with the three scoring systems. Combining lactate, sphinganine and DHEA-S as a metabolite panel for discriminating severe CAP from non-severe CAP exhibited a better AUC of 0.911 (95% confidence interval 0.825-0.998) than CURB-65, PSI and APACHE II scores. CONCLUSIONS: This study demonstrates that serum metabolomics approaches based on the LC-MS/MS platform can be applied as a tool to reveal metabolic changes during CAP and establish a metabolite signature related to disease severity. TRIAL REGISTRATION: ClinicalTrials.gov, NCT03093220 . Registered retrospectively on 28 March 2017.

An unusual case of lung abscess secondary to round pneumonia caused by recurrent Klebsiella pneumoniae strain and the role of occult metastases tumor.

Round pneumonia is an uncommon form of community-acquired pneumonia usually found in children. To this date, there has been no report on local pulmonary complications in this entity in adult patients. The present study reports a case of a 77-year-old male with lung abscess secondary to round pneumonia caused by recurrent Klebsiella pneumoniae infection accompanied by occult metastases tumor. Occult metastases may have played an important role in leading to cavity as in this present case. Further investigation regarding the relationship between recurrent infection and metastases is needed.

Erratum to rhinovirus is associated with severe adult community-acquired pneumonia in China.

[This corrects the article DOI: 10.21037/jtd.2017.10.107.].

Rhinovirus is associated with severe adult community-acquired pneumonia in China.

BACKGROUND: Human rhinovirus (HRV) is one of the most common viral etiologies detected in community-acquired pneumonia (CAP) adult cases. However, few is known about the characteristics of HRV-associated CAP. To describe the clinical features of HRV-associated CAP in immunocompetent adults admitted to multiple medical centers in mainland China over a 2-year period. METHODS: A total of 383 patients admitted to hospitals for CAP were enrolled from 46 medical centers in mainland China between January 2013 and December 2014. Multiplex real-time polymerase chain reaction (RT-PCR) assays for viral detection and DNA-based quantitative loop-mediated isothermal amplification (qLAMP) assays for bacterial detection were implemented to all lower respiratory tract specimens obtained from the patients. Twenty-eight cases (28/383, 7.3%) revealed HRV-positive PCR results. Patients with bronchoalveolar lavage (BAL) HRV-positive PCR results (n=20) were further enrolled and divided into two groups depending on the status of bacterial co-infection (viral group, n=12; viral-Bacterial group, n=8). Demographic, clinical and microbiological data were reviewed and compared in detail. RESULTS: Cases with HRV-infection were remarkably correlated with respiratory failure (14/20) and most of them (13/14) received mechanical ventilation. Fever (17/20), productive cough (15/20) and dyspnea (6/20) were common symptoms while flu-like symptoms were rarely observed in the cohort. Streptococcus pneumoniae (3/8), Klebsiella pneumoniae (3/8) and Mycoplasma pneumoniae (2/8) were most frequently identified bacterium in the viral-bacterial group. Compared with the viral group, higher incidence of septic shock (3/8 vs. 1/12, P=0.255), longer ICU length of stay (LOS) (10.0 vs. 6.5 days, P=0.686), longer hospital LOS (18.5 vs. 13.0 days, P=0.208) and higher 28-day mortality (2/8 vs. 2/12, P=1) were observed in the Viral-Bacterial group, although without statistically significant difference. CONCLUSIONS: HRV is a common etiology in CAP among China adults, especially in severe CAP. Clinicians should be vigilant considering of the poor outcome. Highly qualified multiplex PCR techniques with invasive sampling are needed to increase the detection rate.

Genotyping of human rhinovirus in adult patients with acute respiratory infections identified predominant infections of genotype A21.

Human rhinovirus (HRV) is an important causative agent of acute respiratory tract infections (ARTIs). The roles of specific HRV genotypes in patients suffering from ARTIs have not been well established. We recruited 147 adult inpatients with community-acquired pneumonia (CAP) and 291 adult outpatients with upper ARTIs (URTIs). Respiratory pathogens were screened via PCR assays. HRV was detected in 42 patients, with 35 species A, five B and two C. Seventeen genotypes were identified, and HRV-A21 ranked the highest (9/42, 21.4%). The HRV-A21-positive infections were detected in four patients with CAP and in five with URTIs, all without co-infections. The HRV-A21 genome sequenced in this study contained 12 novel coding polymorphisms in viral protein (VP) 1, VP2 EF loop, VP3 knob and 3D regions. The infections of HRV-A21 virus obtained in this study could not be neutralized by antiserum of HRV-A21 prototype strain (VR-1131), indicating remarkable antigenic variation. Metagenomic analysis showed the HRV-A21 reads were dominant in bronchoalveolar lavage fluid of the three HRV-A21-positive patients with severe CAP, in which two dead. Our results highlight an unexpected infection of genotype HRV-A21 in the clinic, indicating the necessity of precise genotyping and surveillance of HRVs to improve the clinical management of ARTIs.

A preliminary study on the potential of Mycoplasma pneumoniae to induce dyskaryotic change in respiratory epithelium in adult community-acquired pneumonia.

BACKGROUND: This study aimed to explore the cellular morphology of respiratory epithelium in Mycoplasma pneumonia (MpP) patients. MATERIALS AND METHODS: The cast-off cell morphological findings from bronchoscopic brushings in MpP and community-acquired pneumonia (CAP) caused by typical pathogens were reviewed. RESULTS: Compared with the CAP group, cellular dysplasia in respiratory tract epithelial brushings was significantly greater in MpP patients (P = 0.033). CONCLUSION: Unique biological characteristics and mechanisms of pathogenesis of Mycoplasma pneumoniae (Mp) may result in dyskaryotic changes in respiratory epithelium in adult MpP.

Unusual complication of multiple splenic abscesses arising from a feeding jejunostomy tube subsequent to total gastrectomy: A case report and literature review.

Splenic abscess is a rare clinical entity. The present study reports a case of a patient that suffered from splenic abscess secondary to septicemia resulting from Klebsiella pneumoniae infection following the removal of the feeding jejunostomy tube that was utilized subsequent to the patient undergoing total gastrectomy as part of the treatment regimen for gastric adenocarcinoma. The early clinical presentation was nonspecific and multiple splenic abscesses were subsequently identified. To reduce the risks of an additional surgical procedure in this particular patient, laparoscopic assisted splenotomy and catheter drainage were performed. Due to the severe complications that occurred in the present patient, no adjuvant chemotherapy was administered. Therefore, the unusual complication of splenic abscess subsequent to total gastrectomy should be noted, and the routine feeding jejunostomy tube placement at the time of total gastrectomy should be discussed and re-assessed.

Identification of Klebsiella pneumoniae strains harboring inactive extended-spectrum beta-lactamase antibiotic-resistance genes.

BACKGROUND: The extended-spectrum beta-lactamase (ESBL)-producing Klebsiella pneumoniae has increasingly become a major contributor to nosocomial infections and can exhibit multiple antibiotic resistance. Previous studies have focused on the resistance genes in ESBL-producing strains, and the resistance-associated genetic environment of non-ESBL-producing strains has been ignored until now. Here, we investigated the occurrence and characteristics of non-ESBL-producing K. pneumoniae, which potentially carries unexpressed resistance genes. METHODS: K. pneumoniae strains were collected from five medical institutions in China from February 2010 to August 2013. The VITEK-2 ESBL detection system was used as a primary screen to identify the ESBL-producing phenotype, and the three primary types of ESBL-associated genes (CTX, SHV, and TEM) were detected by polymerase chain reaction (PCR) to confirm the strains presenting with a non-ESBL-producing phenotype. mRNA expression in the non-ESBL-producing strains was further screened by reverse-transcription PCR (RT-PCR) to validate their transcriptional efficiency. RESULTS: Out of 224 clinically isolated antibiotic-sensitive K. pneumoniae strains with a non-ESBL-producing phenotype, 5 (2.2%) were identified to carry inactivated ESBL blaSHV genes with intact upstream promoter regions and resistance gene sequences. Interestingly, three of the five antibiotic-sensitive K. pneumoniae strains containing ESBL blaSHV genes still exhibited mRNA transcription of blaSHV, while the other two exhibited no mRNA transcription. CONCLUSION: These findings suggest that inactivated ESBL genes exist in non-ESBL-producing antibiotic-sensitive K. pneumoniae strains, which have the potential to transform the strain into an ESBL phenotype if an inappropriate application or overdose of antibiotics is implemented during clinical management.

Genetic environment of ß-lactamase genes of extended-spectrum ß-lactamase-producing Klebsiella pneumoniae isolates from patients with lower respiratory tract infection in China.

BACKGROUND: Extended-spectrum ß-lactamase (ESBL)-producing Klebsiella pneumoniae (K. pneumoniae) is one of the most popular pathogens that cause refractory respiratory tract infection. The genetic environment, including insertion sequences and the types of promoter, plays a key role in exploration of the mechanism of prevalence and dismission of the ESBL-producing K. pneumoniae isolates. The aim of the investigation was to target analysis the genetic environment and promoter sequences of blaCTX-M, blaSHV and blaTEM, the most popular ß-lactamase genes harbored by ESBL-producing K. pneumoniae isolates. METHODS: From February 2010 to July 2011, 158 of 416 K. pneumoniae isolates producing ESBL from patients with lower respiratory tract infection were collected from seven tertiary hospitals from Beijing, Anhui, Fujian, Liaoning, Hebei and Inner Mongolia Autonomous Region in China. The genetic environment including promoters of 10 types of blaCTX-M, 18 types of blaSHV and 2 types of blaTEM were analyzed by amplification and direct sequencing with various sets of PCR primers. RESULTS: ISEcp1 was located upstream of the 5' end of the blaCTX-M gene in 130 (97.0%) out of 134 K. pneumoniae isolates harboring blaCTX-M and provided a conserved promoter to blaCTX-M. A non-coding sequence preceded by kdpC and recF was identified in all of the blaSHV genes except blaSHV-12 and blaSHV-2a. IS26 was also found upstream of 1 blaCTX-M-15, 10 blaSHV-1 strains, 4 blaTEM-1 and all of the blaSHV-2, blaSHV-2a, blaSHV-5 and blaSHV-12. Eighty-seven of 91 strains harboring blaTEM-1 carried a copy of Tn2 and IS26-blaTEM-1 fragments were also detected in 4 strains. With respect to K. pneumoniae, the genetic environment of blaCTX-M-38, blaSHV-142 and blaTEM-135 were firstly elaborated, and four kinds of novel genetic environment of blaCTX-M-3, blaCTX-M-15 and blaTEM-1 have been detected as well. CONCLUSIONS: Perfective implementation of the genetic environment information of bgr;-lactamase gene needs to be further explored and supplemented. ISEcp1 and IS26 elements are widespread upstream of the blaCTX-M, blaSHV and blaTEM genes and contribute to horizontal transmission and genetic expression.

Heteroresistance at the single-cell level: adapting to antibiotic stress through a population-based strategy and growth-controlled interphenotypic coordination.

UNLABELLED: Heteroresistance refers to phenotypic heterogeneity of microbial clonal populations under antibiotic stress, and it has been thought to be an allocation of a subset of "resistant" cells for surviving in higher concentrations of antibiotic. The assumption fits the so-called bet-hedging strategy, where a bacterial population "hedges" its "bet" on different phenotypes to be selected by unpredicted environment stresses. To test this hypothesis, we constructed a heteroresistance model by introducing a blaCTX-M-14 gene (coding for a cephalosporin hydrolase) into a sensitive Escherichia coli strain. We confirmed heteroresistance in this clone and that a subset of the cells expressed more hydrolase and formed more colonies in the presence of ceftriaxone (exhibited stronger "resistance"). However, subsequent single-cell-level investigation by using a microfluidic device showed that a subset of cells with a distinguishable phenotype of slowed growth and intensified hydrolase expression emerged, and they were not positively selected but increased their proportion in the population with ascending antibiotic concentrations. Therefore, heteroresistance--the gradually decreased colony-forming capability in the presence of antibiotic--was a result of a decreased growth rate rather than of selection for resistant cells. Using a mock strain without the resistance gene, we further demonstrated the existence of two nested growth-centric feedback loops that control the expression of the hydrolase and maximize population growth in various antibiotic concentrations. In conclusion, phenotypic heterogeneity is a population-based strategy beneficial for bacterial survival and propagation through task allocation and interphenotypic collaboration, and the growth rate provides a critical control for the expression of stress-related genes and an essential mechanism in responding to environmental stresses. IMPORTANCE: Heteroresistance is essentially phenotypic heterogeneity, where a population-based strategy is thought to be at work, being assumed to be variable cell-to-cell resistance to be selected under antibiotic stress. Exact mechanisms of heteroresistance and its roles in adaptation to antibiotic stress have yet to be fully understood at the molecular and single-cell levels. In our study, we have not been able to detect any apparent subset of "resistant" cells selected by antibiotics; on the contrary, cell populations differentiate into phenotypic subsets with variable growth statuses and hydrolase expression. The growth rate appears to be sensitive to stress intensity and plays a key role in controlling hydrolase expression at both the bulk population and single-cell levels. We have shown here, for the first time, that phenotypic heterogeneity can be beneficial to a growing bacterial population through task allocation and interphenotypic collaboration other than partitioning cells into different categories of selective advantage.

Predominant characteristics of CTX-M-producing Klebsiella pneumoniae isolates from patients with lower respiratory tract infection in multiple medical centers in China.

From February 2010 to July 2011, 183 of 416 presumptive Klebsiella pneumoniae isolates with reduced susceptibility to third-generation cephalosporins from patients with lower respiratory tract infection were collected from seven tertiary hospitals in China. Phenotypic and genotypic methods were employed to characterize 158 extended-spectrum ß-lactamase (ESBL)-producers. Among the 158 isolates analyzed, 134 (84.8%) harbored bla(CTX-M) , within which the most predominant ESBL gene was CTX-M-14 (49.4%), followed by CTX-M-15 (12.0%) and CTX-M-27 (10.8%). Also, 120 (75.9%) harbored bla(SHV) . One novel SHV variant, bla(SHV -142) with T18A and L35Q substitutions, was identified. Ninety-one isolates carried bla(TEM-1). An isolate containing bla(TEM-135) was first identified in Klebsiella spp. bla(KPC)-2) was detected in 5 isolates. More than one ESBL combination was detected in 18 isolates (11.4%). Fifty-four (34.2%) isolates demonstrated the multidrug resistant (MDR) phenotype. Seventy-four sequence types (STs) were identified, which showed large genetic background diversity in ESBL-producing K. pneumoniae isolates from the six areas. This is the first report on the high prevalence of CTX-M-27 in China with the possible transmission of a single clone (ST48). The correlated surveillance of organisms with MDR phenotype should be investigated in future.

Prevalence and characterization of plasmid-mediated blaESBL with their genetic environment in Escherichia coli and Klebsiella pneumoniae in patients with pneumonia.

BACKGROUND: The extended spectrum ß-lactamase (ESBL)-producing Escherichia coli (E. coli) and Klebsiella pneumoniae (K. pneumoniae) are the major pathogens causing pneumonia and have a significant impact on the clinical course. Limited data exist on molecular characterization of ESBL-producing E. coli and K. pneumoniae that cause pneumonia. The aim of this study was to investigate the comprehensive multilevel characteristics of E. coli and K. pneumoniae causing pneumonia in China for the first time. METHODS: E. coli (17) and K. pneumoniae (21) isolates responsible for pneumonia were isolated from 1270 specimens collected in a prospective multi-center study in eight teaching hospitals in China from June to December in 2007. The susceptibilities, ESBL confirmation, sequence typing, blaCTX-M and blaSHV genes, their genetic environment and plasmid Inc/rep types were determined. RESULTS: Sixteen E. coli (94.1%) and eleven K. pneumoniae (52.4%) isolates were ESBL producers. About 77.8% and 66.7% of them were resistance to ciprofloxacin and levofloxacin, and 100% were susceptible to imipenem. The most prevalent ESBL gene was CTX-M-14, followed by SHV-2, CTX-M-15, CTX-M-3, CTX-M-65, SHV-12, SHV-26 and SHV-28. SHV-1 and SHV-11 were also detected and coexisted with blaCTX-Ms in five strains, and three strains contained only SHV-1. All CTX-M-14 were detected ISEcp1 upstream and nine were found IS903 downstream and the majority of them (64.3%) were carried by IncF plasmids. All blaSHV were flanked by recF and deoR, located on IncF, IncN, IncX and IncH plasmids. Two SHV-2, one SHV-1 and the only SHV-28 were further preceded by IS26. Genes lacY and lacZ were detected at further upstream of two blaSHV-1. The K. pneumoniae carrying SHV-28 was susceptible to ß-lactams, and no mutations or deletions in gene or promoter sequences were identified to account for susceptibility. Multilocus sequence typing experiments showed the ESBL-producing strains were genetically diverse. CONCLUSIONS: The rate of occurrence of blaESBL in E. coli and K. pneumoniae causing pneumonia was high, and blaCTX-M-14 was dominant and probably mobilized by ISEcp1 mainly on IncF plasmids. Importantly, unexpressed blaESBL genes may occur in susceptible isolates and hence may have clinical implications.

Triple combinations of neuraminidase inhibitors, statins and fibrates benefit the survival of patients with lethal avian influenza pandemic.

The high mortality of highly pathogenic avian influenza A (H5N1) viruses infection in humans gives rise to considerable concern that it might someday cause another lethal pandemic. At present there is no other effective alternative besides the early and enough administration of neuraminidase inhibitors, which may be crucial for the patient management. However, its efficacy is sometimes limited because of the late administration in some patients especially the seriously ill ones and the continual occurrence of oseltamivir resistant A (H5N1) strains. The specific candidate vaccine are still under development and the practical value of passive immunization is hard to be widely applied because of the scarcity of convalescent human plasma, especially in the early stage of a serious and rapidly progressing pandemic. Statins and fibrates, both of which are used in clinical practice, have anti-inflammatory and immunomodulatory effects and other multiple biologic activities. So we hypothesized that the two immunomodulatory agents may exhibit synergistic effects when they were combined to neuraminidase inhibitors to treat the A (H5N1) viruses infections via inhibiting the production of either the early inflammatory mediators (e.g., many cytokine/chemokine) or the late mediator (e.g., High Mobility Group Box Protein 1), even showing the anti-viral activities with the prevention of the development of antiviral resistance. Therefore, the novel triple combinations may be an optimal management to confront the next lethal influenza pandemic on its very beginning.

[The effect of subglottic secretion drainage on prevention of ventilator-associated lower airway infection].

OBJECTIVE: To assess the influence of subglottic secretion drainage (SSD) on the morbidity of ventilator-associated pneumonia (VAP) in mechanically ventilated patients. METHODS: All studied patients who received mechanical ventilation (MV) estimated for more than 48 hours were intubated with a special type endotracheal tube with a small-bore cannula in the wall for SSD. The patients were randomly divided into two groups receiving SSD (group A) and usual care (non-SSD, group B) respectively. Bacterial culture of samples from lower airway secretion taken regularly by Bagpipe Protected specimen brush were performed, and at the same time the subglottic secretion and scraping-pharynx specimen were collected for bacterial quantitative culture and antibiotic sensitivity test. The clinical data were recorded and the duration of MV, the length of stay in hospital and the time of occurrence of ventilator-associated airway infection (VAAI) and VAP were analyzed. RESULTS: (1) In patients with MV < 5 days: The incidence of VAAI and VAP in group A (VAAI: 8.3% and VAP: 6.0%) was lower than those in group B (VAAI: 24.0% and VAP: 20.0%, P < 0.05). The onset of VAAI and VAP was delayed in group A [VAAI: (7.4 +/- 3.0) d and VAP: (7.7 +/- 3.2) d] as compared with group B [VAAI: (4.9 +/- 1.4) d and VAP: (4.6 +/- 2.1) d, P < 0.05]. There were no significantly statistic differences for hospital mortality, overall duration of mechanical ventilation, lengths of stay in the hospital between the two groups (P > 0.05). (2) The same organism as that previously found from subglottic secretion was isolated by PSB in 21.4% patients. (3) The concentration of bacteria in subglottic secretion from group A was decreased significantly as compared to that of group B. (4) Gram-negative bacilli were the main pathogens in the lower respiratory tract in the two groups. The dominant bacteria cultured in the lower airway secretions were Pseudomonas aeruginosa and Acinetobacter baumanii. There was no significant difference between the two groups in the spectrum of bacteria (P > 0.05). CONCLUSIONS: (1) SSD reduced the incidence of VAAI and VAP in patients with MV < 5 d. The onset of VAAI and VAP was delayed in group A as compared with group B. The concentration of bacteria in the subglottic secretion was significantly reduced by subglottic secretion drainage. (2) Migration of the dominant bacteria of the subglottic secretion was one of the important factors for VALAI. (3) The dominant cultured bacteria in the lower airway secretion were gram-negative bacilli, most commonly Pseudomonas aeruginosa and Acinetobacter baumanii.