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

Gram-negative pulmonary infections - advances in epidemiology and diagnosis

PURPOSE OF REVIEW

Pulmonary infections due to Gram-negative organisms are increasing worldwide and traditional assumptions that these are limited to hospital and ventilator-acquired pneumonia are rapidly falling away. Accordingly, empiric antibiotic guidelines have to follow suit with ever broader spectrum choices in order to remain 'safe', as the Global prevalence of extensively resistant Gram-negative organisms inexorably increases. Rapid, multiplex PCR-based detection of a wide variety of potential pathogens offers the opportunity to replace empiric antibiotic choices with targeted, evidence-based therapy in clinically actionable timeframes.

RECENT FINDINGS

Here, we describe the data underpinning both the increasing global prevalence of Gram-negative pulmonary infections and their increasing antibiotic resistance. We also describe the performance, characteristics and early emerging clinical impact of already available rapid molecular diagnostic platforms and how they might best be deployed.

SUMMARY

It seems will likely be advantageous to replace the current trend for empiric prescription of increasingly broad-spectrum antibiotics with 'same day' evidence-based, targeted therapy using high performance, rapid molecular diagnostic solutions. Several challenges remain be overcome, however, to fully realize their clear potential for better, focussed deployment of antibiotics, improved patient outcomes and antibiotic stewardship.

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.

Catheterization of mice triggers resurgent urinary tract infection seeded by a bladder reservoir of Acinetobacter baumannii

The antibiotic-resistant bacterium Acinetobacter baumannii is a leading cause of hospital-associated infections. Despite surveillance and infection control efforts, new A. baumannii strains are regularly isolated from health care facilities worldwide. In a mouse model of urinary tract infection, we found that mice infected with A. baumannii displayed high bacterial burdens in urine for several weeks. Two months after the resolution of A. baumannii infection, inserting a catheter into the bladder of mice with resolved infection led to the resurgence of a same-strain urinary tract infection in ~53% of the mice within 24 hours. We identified intracellular A. baumannii bacteria in the bladder epithelial cells of mice with resolved infection, which we propose could act as a host reservoir that was activated upon insertion of a catheter, leading to a resurgent secondary infection.

The threat of multidrug-resistant/extensively drug-resistant Gram-negative respiratory infections: another pandemic

Antibiotic resistance is recognised as a global threat to human health by national healthcare agencies, governments and medical societies, as well as the World Health Organization. Increasing resistance to available antimicrobial agents is of concern for bacterial, fungal, viral and parasitic pathogens. One of the greatest concerns is the continuing escalation of antimicrobial resistance among Gram-negative bacteria resulting in the endemic presence of multidrug-resistant (MDR) and extremely drug-resistant (XDR) pathogens. This concern is heightened by the identification of such MDR/XDR Gram-negative bacteria in water and food sources, as colonisers of the intestine and other locations in both hospitalised patients and individuals in the community, and as agents of all types of infections. Pneumonia and other types of respiratory infections are among the most common infections caused by MDR/XDR Gram-negative bacteria and are associated with high rates of mortality. Future concerns are already heightened due to emergence of resistance to all existing antimicrobial agents developed in the past decade to treat MDR/XDR Gram-negative bacteria and a scarcity of novel agents in the developmental pipeline. This clinical scenario increases the likelihood of a future pandemic caused by MDR/XDR Gram-negative bacteria.