An urgent problem of aerobic gram-negative pathogen infection in complicated parapneumonic effusions or empyemas

Pleural Empyema Due to Proteus Mirabilis in an Adult: A Rarely Encountered Clinical Scenario

The presence of Proteus species in the pleural space is an uncommonly reported entity and is rarely seen even in patients with compromised immune status. We report a case of pleural empyema due to Proteus species in an adult oral cancer patient receiving chemotherapy for academic interest and for generating awareness regarding an expanded pathogenic spectrum of the organism. A 44-year-old salesman, non-smoker and non-alcoholic, presented with sudden-onset shortness of breath, left-sided chest pain, and low-grade fever of one-day duration. He had been recently diagnosed with adenocarcinoma of the tongue and had received two cycles of chemotherapy. After clinical and radiographic evaluation, the patient was diagnosed with left-sided empyema. Following thoracocentesis, the aspirated pus sent for bacterial culture yielded pure growth of Proteus mirabilis. Appropriately modified antibiotic therapy with parenteral piperacillin-tazobactam followed by cefixime, tube drainage, and other supportive therapy resulted in a favorable outcome. After three weeks of hospitalization, the patient was discharged for further planned management of his underlying condition. Though uncommon, the possibility of Proteus species should be kept in mind as a causative agent of thoracic empyema in adults, especially in immunocompromised patients with cancer, diabetes, and renal diseases. The so-called common microorganisms of empyema appear to have altered over time, influenced by anticancer therapy and underlying host immune status. Rapid diagnosis and appropriate antimicrobial therapy usually result in a favorable outcome.

Microbiological profile and antibiotic resistance pattern of empyema thoracis in Calabar, Nigeria

Targeted empirical antibiotic therapy based on local microbiology and antibiotic resistance patterns is essential for the treatment of empyema thoracis. Our retrospective review of 105 pleural empyema culture and sensitivity reports aimed at determining the causative microorganisms and their antimicrobial resistance pattern. Of 105 pleural aspirate samples, 46 (43.8%) were positive on culture. Gram-negative organisms (n = 43) were the predominant isolates, the commonest of which was Klebsiella pneumoniae. It was concluded that empyema thoracis is predominantly caused by Gram-negative organisms in our locality. This should guide protocols on the initiation of empirical therapy.

Recent Insights into the Management of Pleural Infection

Pleural infection in adults has considerable morbidity and continues to be a life-threatening condition. The term “pleural infection” encompasses complicated parapneumonic effusions and primary pleural infections, and includes but is not limited to empyema, which refers to collection of pus in the pleural cavity. The incidence of pleural infection in adults has been continuously increasing over the past two decades, particularly in older adults, and most of such patients have comorbidities. Management of pleural infection requires prolonged duration of hospitalization (average 14 days). There are recognized differences in microbial etiology of pleural infection depending on whether the infection was acquired in the community or in a health-care setting. Anaerobic bacteria are acknowledged as a major cause of pleural infection, and thus anaerobic coverage in antibiotic regimens for pleural infection is mandatory. The key components of managing pleural infection are appropriate antimicrobial therapy and chest-tube drainage. In patients who fail medical therapy by manifesting persistent sepsis despite standard measures, surgical intervention to clear the infected space or intrapleural fibrinolytic therapy (in poor surgical candidates) are recommended. Recent studies have explored the role of early intrapleural fibrinolytics or first-line surgery, but due to considerable costs of such interventions and the lack of convincing evidence of improved outcomes with early use, early intervention cannot be recommended, and further evidence is awaited from ongoing studies. Other areas of research include the role of routine molecular testing of infected pleural fluid in improving the rate of identification of causative organisms. Other research topics include the benefit of such interventions as medical thoracoscopy, high-volume pleural irrigation with saline/antiseptic solution, and repeated thoracentesis (as opposed to chest-tube drainage) in reducing morbidity and improving outcomes of pleural infection. This review summarizes current knowledge and practice in managing pleural infection and future research directions.

The microbiology of pleural infection in adults: a systematic review

BACKGROUND AND OBJECTIVES

Pleural infection is a major cause of morbidity and mortality among adults. Identification of the offending organism is key to appropriate antimicrobial therapy. It is not known whether the microbiological pattern of pleural infection is variable temporally or geographically. This systematic review aimed to investigate available literature to understand the worldwide pattern of microbiology and the factors that might affect such pattern.

DATA SOURCES AND ELIGIBILITY CRITERIA

Ovid MEDLINE and Embase were searched between 2000 and 2018 for publications that reported on the microbiology of pleural infection in adults. Both observational and interventional studies were included. Studies were excluded if the main focus of the report was paediatric population, tuberculous empyema or post-operative empyema.

STUDY APPRAISAL AND SYNTHESIS METHODS

Studies of ≥20 patients with clear reporting of microbial isolates were included. The numbers of isolates of each specific organism/group were collated from the included studies. Besides the overall presentation of data, subgroup analyses by geographical distribution, infection setting (community versus hospital) and time of the report were performed.

RESULTS

From 20 980 reports returned by the initial search, 75 articles reporting on 10 241 patients were included in the data synthesis. The most common organism reported worldwide was Staphylococcus aureus. Geographically, pneumococci and viridans streptococci were the most commonly reported isolates from tropical and temperate regions, respectively. The microbiological pattern was considerably different between community- and hospital-acquired infections, where more Gram-negative and drug-resistant isolates were reported in the hospital-acquired infections. The main limitations of this systematic review were the heterogeneity in the method of reporting of certain bacteria and the predominance of reports from Europe and South East Asia.

CONCLUSIONS

In pleural infection, the geographical location and the setting of infection have considerable bearing on the expected causative organisms. This should be reflected in the choice of empirical antimicrobial treatment.

A systematic review of comorbidities and outcomes of adult patients with pleural infection

Background

Pleural infection remains an important cause of mortality. This study aimed to investigate worldwide patterns of pre-existing comorbidities and clinical outcomes of patients with pleural infection.

Methods

Studies reporting on adults with pleural infection between 2000 and 2017 were identified from a search of Embase and MEDLINE. Articles reporting exclusively on tuberculous, fungal or post-pneumonectomy infection were excluded. Two reviewers assessed 20 980 records for eligibility.

Results

211 studies met the inclusion criteria. 134 articles (227 898 patients, mean age 52.8 years) reported comorbidity and/or outcome data. The majority of studies were retrospective observational cohorts (n=104, 78%) and the most common region of reporting was East Asia (n=33, 24%) followed by North America (n=27, 20%). 85 articles (50 756 patients) reported comorbidity. The median (interquartile range (IQR)) percentage prevalence of any comorbidity was 72% (58–83%), with respiratory illness (20%, 16–32%) and cardiac illness (19%, 15–27%) most commonly reported. 125 papers (192 298 patients) reported outcome data. The median (IQR) length of stay was 19 days (13–27 days) and median in-hospital or 30-day mortality was 4% (IQR 1–11%). In regions with high-income economies (n=100, 74%) patients were older (mean 56.5 versus 42.5 years, p<0.0001), but there were no significant differences in prevalence of pre-existing comorbidity nor in length of hospital stay or mortality.

Conclusion

Patients with pleural infection have high levels of comorbidity and long hospital stays. Most reported data are from high-income economy settings. Data from lower-income regions is needed to better understand regional trends and enable optimal resource provision going forward.

In pleural infection, patients from higher-income countries tend to be older with more comorbidities and are more likely to be referred for fibrinolytic treatment in comparison to patients from lower-income countrieshttp://bit.ly/2K2M5HL

Population-based cohort study investigating the correlation of diabetes mellitus with pleural empyema in adults in Taiwan

We assessed the association between diabetes mellitus and the risk of pleural empyema in Taiwan.A population-based retrospective cohort study was conducted using the database of the Taiwan National Health Insurance Program. There were 28,802 subjects aged 20 to 84 years who were newly diagnosed with diabetes mellitus from 2000 to 2010 as the diabetes group and 114,916 randomly selected subjects without diabetes mellitus as the non-diabetes group. The diabetes group and the non-diabetes group were matched by sex, age, comorbidities, and the year of index date. The incidence of pleural empyema at the end of 2011 was estimated. A multivariable Cox proportional hazards regression model was used to estimate the hazard ratio (HR) and 95% confidence interval (95% CI) for pleural empyema associated with diabetes mellitus.The overall incidence of pleural empyema was 1.65-fold higher in the diabetes group than that in the non-diabetes group (1.58 vs 0.96 per 10,000 person-years, 95% CI 1.57-1.72). After adjusting for confounders, a multivariable Cox proportional hazards regression model revealed that the adjusted HR of pleural empyema was 1.71 in subjects with diabetes mellitus (95% CI 1.16-2.51), compared with those without diabetes mellitus. In further analysis, even in the absence of any comorbidity, the adjusted HR was 1.99 for subjects with diabetes mellitus alone (95% CI 1.18-3.38).Diabetic patients confer a 1.71-fold increased hazard of developing pleural empyema. Even in the absence of any comorbidity, the risk remains existent.

The increasing incidence of empyema

PURPOSE OF REVIEW

The aim of this review is to highlight recent changes concerning the incidence of empyema. In this article we have focused on community-acquired empyema

RECENT FINDINGS

The incidence of empyema seems to have been increasing both in children and adults worldwide in the past decades, mainly in healthy young adults and in older patients. The bacteriology of pleural infection is changing as well. In children, the most common microorganism that causes empyema continues to be Streptococcus pneumoniae. Interestingly, the widespread use of the seven valent conjugate vaccine has produced a replacement phenomenon with the emergence of some pneumococcal serotypes such as serotypes 1, 3 and 19A, which have a higher propensity to cause empyema. Moreover increases in the incidence of empyema due to Staphylococcus aureus have also been observed. In adults, increases in the rate of empyema due to Streptococcus milleri group and S. aureus have been reported.

SUMMARY

Continued surveillance in the epidemiology of empyema is needed. Progress in new strategies of prevention, such as a new generation of conjugate pneumococcal vaccines and protein-based vaccines, could become an important step in the control of this important complication.

Rapid label-free identification of mixed bacterial infections by surface plasmon resonance

Background

Early detection of mixed aerobic-anaerobic infection has been a challenge in clinical practice due to the phenotypic changes in complex environments. Surface plasmon resonance (SPR) biosensor is widely used to detect DNA-DNA interaction and offers a sensitive and label-free approach in DNA research.

Methods

In this study, we developed a single-stranded DNA (ssDNA) amplification technique and modified the traditional SPR detection system for rapid and simultaneous detection of mixed infections of four pathogenic microorganisms (Pseudomonas aeruginosa, Staphylococcus aureus, Clostridium tetani and Clostridium perfringens).

Results

We constructed the circulation detection well to increase the sensitivity and the tandem probe arrays to reduce the non-specific hybridization. The use of 16S rDNA universal primers ensured the amplification of four target nucleic acid sequences simultaneously, and further electrophoresis and sequencing confirmed the high efficiency of this amplification method. No significant signals were detected during the single-base mismatch or non-specific probe hybridization (P < 0.05). The calibration curves of amplification products of four bacteria had good linearity from 0.1 nM to 100 nM, with all R² values of >0.99. The lowest detection limits were 0.03 nM for P. aeruginosa, 0.02 nM for S. aureus, 0.01 nM for C. tetani and 0.02 nM for C. perfringens. The SPR biosensor had the same detection rate as the traditional culture method (P < 0.05). In addition, the quantification of PCR products can be completed within 15 min, and excellent regeneration greatly reduces the cost for detection.

Conclusions

Our method can rapidly and accurately identify the mixed aerobic-anaerobic infection, providing a reliable alternative to bacterial culture for rapid bacteria detection.

Clinical and microbiological characteristics of community-acquired thoracic empyema or complicated parapneumonic effusion caused by Klebsiella pneumoniae in Taiwan

Klebsiella pneumoniae is the major cause of community-acquired pyogenic infections in Taiwan and is becoming an increasing problem in acute thoracic empyema. This study evaluated the clinical and microbiological characteristics of community-acquired thoracic empyema or complicated parapneumonic effusion caused by K. pneumoniae in Taiwanese adults treated during the period 2001-2008 at a tertiary medical center. All clinical isolates were examined for capsular serotypes K1/K2, and pulsed-field gel electrophoresis (PFGE) was performed on strains of the same serotype. K. pneumoniae was the most frequent cause of community-acquired thoracic empyema or complicated parapneumonic effusion. It was associated with high mortality (32.4%) and was an independent risk factor for fatal outcome. Diabetes mellitus, liver cirrhosis, and bronchogenic carcinoma were independent risk factors for K. pneumoniae infection. Serotypes K1 (9/37, 24.3%) and K2 (13/37, 35.1%) were the prevalent strains but did not predispose patients to poor outcome compared with other non-K1/K2 serotypes. There was no major cluster of isolates found among serotype K1/K2 strains. In summary, physicians should be aware of the risk factors for thoracic empyema or complicated parapneumonic effusion caused by K. pneumoniae and the associated high mortality, and monitor these patients more closely.

Interventional management of pleural infections

Pleural infections represent an important group of disorders that is characterized by the invasion of pathogens into the pleural space and the potential for rapid progression to frank empyema. Previous epidemiologic studies have indicated that empyema is increasing in prevalence, which underscores the importance of urgent diagnosis and effective drainage to improve clinical outcomes. Unfortunately, limited evidence exists to guide clinicians in selecting the ideal drainage intervention for a specific patient because of the broad variation that exists in the intrapleural extent of infection, presence of locules, comorbid features, respiratory status, and virulence of the underlying pathogen. Moreover, many patients experience delays in both the recognition of infected pleural fluid and the initiation of appropriate measures to drain the pleural space. The present review provides an update on the pathogenesis and interventional therapy of pleural infections with an emphasis on the unique role of image-guided drainage with small-bore catheters.