Empiric therapy for gram-negative pathogens in nosocomial and health care-associated pneumonia: starting with the end in mind

Frequency of occurrence and antimicrobial susceptibility of bacteria isolated from respiratory samples of patients hospitalized with pneumonia in Western Europe, Eastern Europe and the USA: results from the SENTRY Antimicrobial Surveillance Program (2016-19)

Background

The SENTRY Antimicrobial Surveillance Program monitors the frequency of occurrence and antimicrobial susceptibility of organisms from various infection types worldwide.

Objectives

To evaluate the SENTRY programme results for organisms isolated from respiratory samples of patients hospitalized with probable pneumonia.

Methods

A total of 28 918 bacterial isolates were consecutively collected (one per patient) in 2016-19 from 121 medical centres located in western Europe (W-EU; n = 7966), eastern Europe (E-EU; n = 3182) and the USA (n = 17 770) and then susceptibility tested by reference broth microdilution methods in a central laboratory.

Results

Gram-negative bacilli (GNB) represented 76.3%, 88.6% and 69.1% of organisms; non-fermentative (NF) GNB accounted for 26.9%, 51.8% and 34.6% of organisms in W-EU, E-EU and USA, respectively. Pseudomonas aeruginosa susceptibility to piperacillin/tazobactam and meropenem was 75.4% and 76.9% in W-EU, 57.4% and 48.3% in E-EU, and 76.1% and 74.8% in the USA, respectively. Only 10.4% of Acinetobacter baumannii isolates from E-EU were meropenem susceptible compared with 45.8% in W-EU and 58.8% in the USA. Overall MRSA rates were 21.4% in W-EU and 28.7% in E-EU. In the USA, MRSA rates decreased from 44.8% in 2016 to 40.1% in 2019. Carbapenem resistance among Enterobacterales decreased continuously in the USA from 3.0% in 2016 to 1.7% in 2019 (2.4% overall) and was higher in E-EU (16.6%) than W-EU (2.2%). Klebsiella pneumoniae susceptibility to meropenem was 91.3%, 72.5% and 95.3% in W-EU, E-EU and the USA, respectively.

Conclusions

Rank order and antimicrobial susceptibility of bacteria isolated from patients with pneumonia widely varied by geography. MDR NF-GNB represented an important cause of pneumonia.

Geographical and temporal variation in the frequency and antimicrobial susceptibility of bacteria isolated from patients hospitalized with bacterial pneumonia: results from 20 years of the SENTRY Antimicrobial Surveillance Program (1997-2016)

BACKGROUND

The SENTRY Antimicrobial Surveillance Program monitors the frequency of occurrence and antimicrobial susceptibility of organisms from various infection types worldwide.

METHODS

A total of 102 995 bacterial isolates were consecutively collected (one per patient) in 1997-2016 from 258 medical centres in North America (n = 44 999; 113 centres), Europe (n = 30 988; 61 centres from 22 nations), the Asia-Pacific region (APAC; n = 16 503; 67 centres from 12 nations) and Latin America (n = 10 505; 17 centres from 7 nations). Organisms were isolated from respiratory tract specimens and tested for susceptibility by broth microdilution methods in a central laboratory.

RESULTS

Staphylococcus aureus (n = 24 351) and Pseudomonas aeruginosa (n = 22 279) were the most common organisms overall. Klebsiella spp. (n = 10 565) ranked third in North America, Europe and APAC. The proportion of Gram-negatives increased from 70.0%-74.7% to 80.9%-82.6% in Europe, APAC and Latin America, and remained stable (65.5%-66.1%) in North America. Methicillin resistance rates decreased substantially in all four regions from 2005-06 to 2015-16 among S. aureus isolates. P. aeruginosa susceptibility to meropenem decreased overall in the initial years, but increased in the last years of the investigation. Among Klebsiella spp. isolates, susceptibility to ceftriaxone/meropenem decreased from 85.9%/99.3% to 58.6%/85.8% in Europe and from 91.8%/99.5% to 81.6%/93.9% in APAC during the study period.

CONCLUSIONS

Rank order and susceptibility rates varied widely by geographical region and over time. The occurrence of some resistance phenotypes increased, though others decreased over the 20 years of the SENTRY Antimicrobial Surveillance Program.

Spray dried curcumin loaded nanoparticles for antimicrobial photodynamic therapy

Antimicrobial resistance is one of the most serious problems that researchers of multiple disciplines are working on. The number of new antibiotics and their targeted structures have continuously decreased emphasizing the demand of alternative therapy for bacterial infections. Photodynamic therapy is such a promising strategy that has been proven to be effective against a wide range of bacterial strains. In this study, an inhalable nanoformulation for photodynamic therapy against respiratory infections was developed in the form of nano-in-microparticles consisting of curcumin nanoparticles embedded in a mannitol matrix. The produced nano-in-microparticles exhibited suitable aerodynamic properties with a mass median aerodynamic diameter of 2.88 ± 0.13 µm and a high fine particle fraction of 60.99 ± 9.50%. They could be readily redispersed in an aqueous medium producing the original nanoparticles without any substantial changes in their properties. This was confirmed using dynamic light scattering and electron microscopy. Furthermore, the redispersed nanoparticles showed an efficient antibacterial photoactivity causing 99.99992% (6.1log₁₀) and 97.75% (1.6log₁₀) reduction in the viability of Staphylococcus saprophyticus subsp. bovis and Escherichia coli DH5 alpha respectively. Based on these findings, it can be concluded that nano-in-microparticles represent promising drug delivery systems for antimicrobial photodynamic therapy.

Optimization of therapy against Pseudomonas aeruginosa with ceftazidime and meropenem using chemostats as model for infections

Pseudomonas aeruginosa is an opportunistic pathogen that can cause life-threatening infections in patients admitted to intensive care units. Resistance rapidly develops against two drugs of choice: ceftazidime and meropenem. Several therapeutic protocols were compared for reduction in viable cells and limiting development of resistance. Chemostat cultures were exposed to antibiotic concentrations measured in the blood of patients at low (5th percentile), medium (50th percentile) or high (95th percentile) levels in several therapy protocols to simulate therapy. Cultures exposed to ceftazidime recovered after 1 day at low, 2 days at medium and 3 days at high concentrations and developed corresponding levels of resistance. Patterns were very similar for meropenem except that recovery was delayed. Fluctuating levels and intermittent treatment achieved similar reduction of cell numbers at lower resistance costs. Treatment alternating ceftazidime and meropenem reduced cell numbers more than monotherapy, while strongly limiting resistance. Combination therapy was even more effective in both respects. Therapeutic goals are best reached with least risk of resistance when ceftazidime and meropenem are used in combination or alternating, at the highest concentrations the patient can endure. Monotherapy should also apply the highest concentration that is safe for the shortest time that achieves treatment objectives.

Antimicrobial Activity of Ceftazidime-Avibactam against Gram-Negative Bacteria Isolated from Patients Hospitalized with Pneumonia in U.S. Medical Centers, 2011 to 2015

Bacterial isolates were collected from patients hospitalized with pneumonia (PHP), including ventilator-associated pneumonia (VAP), from 76 U.S. medical centers in 2011 to 2015. The Gram-negative organisms (n = 11,185, including 1,097 from VAP) were tested for susceptibility to ceftazidime-avibactam and comparators by the broth microdilution method. β-Lactamase-encoding genes were screened using a microarray-based assay on selected isolates. Pseudomonas aeruginosa and Klebsiella spp. were the most common Gram-negative bacteria isolated from PHP and VAP. Ceftazidime-avibactam was very active against P. aeruginosa (n = 3,402; MIC₅₀/MIC₉₀, 2 and 4 μg/ml; 96.6% susceptible), including isolates nonsusceptible to meropenem (86.3% susceptible to ceftazidime-avibactam), piperacillin-tazobactam (85.6% susceptible), or ceftazidime (80.6% susceptible). Ceftazidime-avibactam was also highly active against Enterobacteriaceae (MIC₅₀/MIC₉₀, 0.12 and 0.5 μg/ml; 99.9% susceptible), including carbapenem-resistant Enterobacteriaceae (CRE) (n = 189; MIC₅₀/MIC₉₀, 0.5 and 2 μg/ml; 98.0% susceptible) and multidrug-resistant (MDR) (n = 674; MIC₅₀/MIC₉₀, 0.25 and 1 μg/ml; 98.8% susceptible) and extensively drug-resistant (XDR) (n = 156; MIC₅₀/MIC₉₀, 0.5 and 2 μg/ml; 98.1% susceptible) Enterobacteriaceae isolates, as well as Klebsiella species isolates showing an extended-spectrum β-lactamase (ESBL) screening-positive phenotype (n = 433; MIC₅₀/MIC₉₀, 0.25 and 1 μg/ml; 99.5% susceptible). Among Enterobacter spp. (24.8% ceftazidime nonsusceptible), 99.8% of the isolates, including 99.4% of ceftazidime-nonsusceptible isolates, were susceptible to ceftazidime-avibactam. The most common β-lactamases detected among Klebsiella pneumoniae and E. coli isolates were K. pneumoniae carbapenemase (KPC)-like and CTX-M-15, respectively. Only 8 of 6,209 Enterobacteriaceae isolates (0.1%) were ceftazidime-avibactam nonsusceptible, three NDM-1-producing strains with ceftazidime-avibactam MIC values of >32 μg/ml and five isolates with ceftazidime-avibactam MIC values of 16 μg/ml and negative results for all β-lactamases tested. Susceptibility rates among isolates from VAP were generally similar or slightly higher than those from all PHP.

Clinical Effect and Efficacy Factors of Modified Piperacillin-Tazobactam Dosing Regimens in Abdominal Tumor Patients with Post-Operative Pneumonia

BACKGROUND

This study was conducted to observe the clinical efficacy of long-term piperacillin-tazobactam (TZP) infusion and identify the factors affecting its curative effect against pneumonia in patients who had undergone surgery for abdominal tumor.

METHODS

The 100 patients were divided into four clinical groups according to the severity of their infection: Simple pneumonia, pneumonia with pleural effusion, pneumonia and atelectasis, and severe pneumonia. Each group of patients was then divided into control and treatment groups using a completely random design. The control group received TZP as a regular infusion, and the treatment group received TZP as a long-term infusion. The cure time in the different groups was compared according to the administration regimen, and stratified analysis was carried out to identify the efficacy factors of long-term TZP infusion for patients with each kind of pneumonia.

RESULTS

The average cure time for TZP differed significantly among the groups. In particular, the average cure times in the simple pneumonia, pneumonia with pleural effusion, pneumonia and atelectasis, and severe pneumonia groups were 6.800 ± 0.342, 7.320 ± 0.304, 10.840 ± 0.571, and 15.942 ± 0.973 d (p < 0.001). In each group, the usage time of antibiotics in the treatment groups was significantly shorter than in the control group (8.87 ± 0.64 vs. 15.95 ± 2.02 d; p < 0.001). The cure times (d) for simple pneumonia and pneumonia and atelectasis were conspicuously lower in the treatment groups than in the control group (5.667 ± 0.256 vs. 7.846 ± 0.451; p < 0.001; 9.667 ± 1.432 vs. 11.923 ± 0.947; p = 0.024). The factors associated with continuous treatment effectiveness were being male, age <70 years, Acute Physiology and Chronic Health Evaluation score ≥17 points, minimum inhibitory concentration of the pathogen 8 mcg/mL, oxygenation index >200 mm Hg, serum procalcitonin concentration >4 ng/mL, and serum albumin <25 g/L.

CONCLUSION

Long-term TZP infusion exhibited better clinical efficacy than did traditional treatment in patients with pneumonia after abdominal tumor surgery.

Characteristics of an ideal nebulized antibiotic for the treatment of pneumonia in the intubated patient

Gram-negative pneumonia in patients who are intubated and mechanically ventilated is associated with increased morbidity and mortality as well as higher healthcare costs compared with those who do not have the disease. Intravenous antibiotics are currently the standard of care for pneumonia; however, increasing rates of multidrug resistance and limited penetration of some classes of antimicrobials into the lungs reduce the effectiveness of this treatment option, and current clinical cure rates are variable, while recurrence rates remain high. Inhaled antibiotics may have the potential to improve outcomes in this patient population, but their use is currently restricted by a lack of specifically formulated solutions for inhalation and a limited number of devices designed for the nebulization of antibiotics. In this article, we review the challenges clinicians face in the treatment of pneumonia and discuss the characteristics that would constitute an ideal inhaled drug/device combination. We also review inhaled antibiotic options currently in development for the treatment of pneumonia in patients who are intubated and mechanically ventilated.

Antimicrobial susceptibility of Gram-negative organisms isolated from patients hospitalised with pneumonia in US and European hospitals: results from the SENTRY Antimicrobial Surveillance Program, 2009-2012

Here we evaluated the frequency of occurrence and antimicrobial susceptibility patterns of Gram-negative bacteria isolated from patients hospitalised with pneumonia in medical centres in the USA (n=28) and Europe and the Mediterranean region (EMR) (n=25) in 2009-2012. Susceptibility testing was performed by reference broth microdilution methods. Overall, 12851 isolates were collected (6873/5978 in USA/EMR). The same top 11 organisms were observed in both geographic regions, but in different rank orders, and Gram-negative organisms represented 61.5/76.1% of strains in USA/EMR. Pseudomonas aeruginosa was the most frequently isolated Gram-negative organism in both regions (20.9/20.9% of cases in USA/EMR) and showed reduced susceptibility to most antimicrobials tested, including ceftazidime (79.6/68.7% susceptibility in USA/EMR), meropenem (76.3/65.8%) and piperacillin/tazobactam (72.9/63.9%). Klebsiella spp. was isolated from 9.7/11.6% of cases and showed extended-spectrum β-lactamase (ESBL) phenotype rates of 19.5/35.1% in USA/EMR. Meropenem and amikacin were active against 62.3/78.7% and 60.8/85.2% of ESBL phenotype Klebsiella spp. from USA/EMR, respectively. Enterobacter spp. ranked fourth in the USA (5.9%) and sixth in EMR (5.5%), whereas Escherichia coli ranked fifth in the USA (5.5%) and third in EMR (11.8%). Acinetobacter spp. and Stenotrophomonas maltophilia combined were isolated from 8.0/10.7% of cases in USA/EMR. A significant increase in P. aeruginosa susceptibility to meropenem and a significant decrease in gentamicin susceptibility among Klebsiella spp. were noted in EMR. These results confirm that very few agents remain broadly active against the most frequently isolated Gram-negative organisms from patients with pneumonia in US and EMR medical centres.

Infectious Disease Management through Point-of-Care Personalized Medicine Molecular Diagnostic Technologies

Infectious disease management essentially consists in identifying the microbial cause(s) of an infection, initiating if necessary antimicrobial therapy against microbes, and controlling host reactions to infection. In clinical microbiology, the turnaround time of the diagnostic cycle (>24 hours) often leads to unnecessary suffering and deaths; approaches to relieve this burden include rapid diagnostic procedures and more efficient transmission or interpretation of molecular microbiology results. Although rapid nucleic acid-based diagnostic testing has demonstrated that it can impact on the transmission of hospital-acquired infections, we believe that such life-saving procedures should be performed closer to the patient, in dedicated 24/7 laboratories of healthcare institutions, or ideally at point of care. While personalized medicine generally aims at interrogating the genomic information of a patient, drug metabolism polymorphisms, for example, to guide drug choice and dosage, personalized medicine concepts are applicable in infectious diseases for the (rapid) identification of a disease-causing microbe and determination of its antimicrobial resistance profile, to guide an appropriate antimicrobial treatment for the proper management of the patient. The implementation of point-of-care testing for infectious diseases will require acceptance by medical authorities, new technological and communication platforms, as well as reimbursement practices such that time- and life-saving procedures become available to the largest number of patients.