The Efficacy of Using Combination Therapy against Multi-Drug and Extensively Drug-Resistant Pseudomonas aeruginosa in Clinical Settings

Safety of Nebulized Ciprodex for Postoperative Management of Tracheal Resection

OBJECTIVE

Anastomotic complications after tracheal resection/cricotracheal resection (TR/CTR), such as granulation tissue formation, can lead to severe morbidity. The off-label use of nebulized ciprofloxacin-dexamethasone (Ciprodex) for granulation tissue prophylaxis has anecdotally been used after TR/CTR, especially in pediatric patients. However, its use in the adult population, and its safety and side effect profile post-TR/CTR has not been reported. This study aims to characterize the incidence of adverse side effects associated with nebulized Ciprodex in post-TR/CTR patients.

METHODS

A retrospective review of all patients who underwent TR/CTR from June 2015 to July 2023 was performed. The use of nebulized Ciprodex (1 mL ciprofloxacin-dexamethasone 0.3%-0.1% otic suspension in 4 mL normal saline) while inpatient was evaluated. Potential side effects were defined as oral thrush, ageusia, arthralgia, and allergic reaction, and were recorded for all patients.

RESULTS

Seventy-three patients underwent TR/CTR from June 2015 to July 2023. Of these, 53 (72.6%) had documented Ciprodex administration during their postoperative course. One (1.9%) patient reported at least one side effect, including one instance of skin rash (1.9%) and one instance of allergic reaction (1.9%). There were no other side effects attributed to Ciprodex use.

CONCLUSIONS

The incidence of side effects related to the use of nebulized Ciprodex is felt to be minimal in post-TR/CTR. Although Ciprodex may have the potential to treat granulation tissue in the airway, further studies are needed to verify its efficacy and safety.

LEVEL OF EVIDENCE

4 Laryngoscope, 134:3695-3697, 2024.

Systematic Review of Beta-Lactam vs. Beta-Lactam plus Aminoglycoside Combination Therapy in Neutropenic Cancer Patients

We performed a systematic review of studies that compared beta-lactams vs. beta-lactams plus aminoglycosides for the treatment of febrile neutropenia in cancer patients.

METHOD

We searched CENTRAL, MEDLINE, and Embase for studies published up to October 2023, and randomized controlled trials (RCTs) that compared anti-Pseudomonas aeruginosa beta-lactam monotherapy with any combination of an anti-Pseudomonas aeruginosa beta-lactam and an aminoglycoside were included.

RESULT

The all-cause mortality rate of combination therapy showed no significant differences compared with that of monotherapy (RR 0.99, 95% CI 0.84 to 1.16, high certainty of evidence). Infection-related mortality rates showed that combination therapy had a small positive impact compared with the intervention with monotherapy (RR 0.83, 95% CI 0.66 to 1.05, high certainty of evidence). Regarding treatment failure, combination therapy showed no significant differences compared with monotherapy (RR 0.99, 95% CI 0.94 to 1.03, low certainty of evidence). In the sensitivity analysis, the treatment failure data published between 2010 and 2019 showed better outcomes in the same beta-lactam group (RR 1.10 [95% CI, 1.01-1.19]). Renal failure was more frequent with combination therapy of any daily dosing regimen (RR 0.46, 95% CI 0.36 to 0.60, high certainty of evidence).

CONCLUSION

We found combining aminoglycosides with a narrow-spectrum beta-lactam did not spare the use of broad-spectrum antibiotics. Few studies included antibiotic-resistant bacteria and a detailed investigation of aminoglycoside serum levels, and studies that combined the same beta-lactams showed only a minimal impact with the combination therapy. In the future, studies that include the profile of antibiotic-resistant bacteria and the monitoring of serum aminoglycoside levels will be required.

Evaluation of fortimicin antibiotic combinations against MDR Pseudomonas aeruginosa and resistome analysis of a whole genome sequenced pan-drug resistant isolate

BACKGROUND

Multidrug-resistant (MDR) P. aeruginosa is a rising public health concern, challenging the treatment of such a ubiquitous pathogen with monotherapeutic anti-pseudomonal agents. Worryingly, its genome plasticity contributes to the emergence of P. aeruginosa expressing different resistant phenotypes and is now responsible for notable epidemics within hospital settings. Considering this, we aimed to evaluate the synergistic combination of fortimicin with other traditional anti-pseudomonal agents and to analyze the resistome of pan-drug resistant (PDR) isolate.

METHODS

Standard methods were used for analyzing the antimicrobial susceptibility tests. The checkerboard technique was used for the in vitro assessment of fortimicin antibiotic combinations against 51 MDR P. aeruginosa and whole genome sequencing was used to determine the resistome of PDR isolate.

RESULTS

Out of 51 MDR P. aeruginosa, the highest synergistic effect was recorded for a combination of fortimicin with β-lactam group as meropenem, ceftazidime, and aztreonam at 71%, 59% and 43%, respectively. Of note, 56.8%, 39.2%, and 37.2% of the tested MDR isolates that had synergistic effects were also resistant to meropenem, ceftazidime, and aztreonam, respectively. The highest additive effects were recorded for combining fortimicin with amikacin (69%) and cefepime (44%) against MDR P. aeruginosa. Resistome analysis of the PDR isolate reflected its association with the antibiotic resistance phenotype. It ensured the presence of a wide variety of antibiotic-resistant genes (β-lactamases, aminoglycosides modifying enzymes, and efflux pump), rendering the isolate resistant to all clinically relevant anti-pseudomonal agents.

CONCLUSION

Fortimicin in combination with classical anti-pseudomonal agents had shown promising synergistic activity against MDR P. aeruginosa. Resistome profiling of PDR P. aeruginosa enhanced the rapid identification of antibiotic resistance genes that are likely linked to the appearance of this resistant phenotype and may pave the way to tackle antimicrobial resistance issues shortly.

Antibiotic Adjuvant 4-Hexylresorcinol Enhances the Efficiency of Antituberculosis Drugs

We studied the possibility of using 4-hexylresorcinol to increase the efficiency of anti-mycobacterial chemotherapy. In an in vitro experiment, 4-hexylresorcinol increased the efficiency of rifampicin, kanamycin, and isoniazid against Mycobacterium smegmatis by 3-5 times. Experiments in sanitation of BALB/c mice infected with M. smegmatis showed the best efficacy of the isoniazid and 4-hexylresorcinol combination in comparison with isoniazid monotherapy. The growth-inhibiting activity of the combination of antibiotic rifabutin with 4-hexylresorcinol was shown on 6 strains of M. tuberculosis. A 2-fold decrease in the minimum inhibitory concentration of this antibiotic in the presence of half-minimum inhibitory concentration of 4-hexylresorcinol was demonstrated for monoresistant strain M. tuberculosis 5360/42Hr. On the mouse model of experimental tuberculosis caused by M. tuberculosis H37Rv, a 5-fold decrease in lung contamination and more rapid complete cure were achieved in animals treated with the combination of rifabutin and 4-hexylresorcinol in comparison with rifabutin monotherapy.

Combinatorial application of cuminaldehyde and gentamicin shows enhanced antimicrobial and antibiofilm action on Pseudomonas aeruginosa

The emergence of biofilm-induced drug tolerance poses a critical challenge to public healthcare management. Pseudomonas aeruginosa, a gram-negative opportunistic bacterium, is involved in various biofilm-associated infections in human hosts. Towards this direction, in the present study, a combinatorial approach has been explored as it is a demonstrably effective strategy for managing microbial infections. Thus, P. aeruginosa has been treated with cuminaldehyde (a naturally occurring phytochemical) and gentamicin (an aminoglycoside antibiotic) in connection to the effective management of the biofilm challenges. It was also observed that the test molecules could show increased antimicrobial activity against P. aeruginosa. A fractional inhibitory concentration index (FICI) of 0.65 suggested an additive interaction between cuminaldehyde and gentamicin. Besides, a series of experiments such as crystal violet assay, estimation of extracellular polymeric substance (EPS), and microscopic images indicated that an enhanced antibiofilm activity was obtained when the selected compounds were applied together on P. aeruginosa. Furthermore, the combination of the selected compounds was found to reduce the secretion of virulence factors from P. aeruginosa. Taken together, this study suggested that the combinatorial application of cuminaldehyde and gentamicin could be considered an effective approach towards the control of biofilm-linked infections caused by P. aeruginosa.

Diversity of biofilm-specific antimicrobial resistance genes in Pseudomonas aeruginosa recovered from various clinical isolates

Background and Objectives

The resistance of Pseudomonas aeruginosa to antibiotics offers a significant challenge in the treatment of patients. This study aimed to investigate the antimicrobial resistance profile, biofilm-specific antimicrobial resistance genes, and genetic diversity of P. aeruginosa recovered from clinical samples.

Materials and Methods

Totally 47 non-duplicate isolates of P. aeruginosa were recovered from various clinical samples. toxA, algD, ndvB, and tssC1 genes were detected in biofilm-producing isolates. The DNA sequences of the toxA and tssC1 genes were analyzed, by creating phylogenetic trees.

Results

The findings revealed that 30 (63.8%) of the isolates tested positive for Extended spectrum β-lactamase (ESBL), whereas 31 (65.9%) tested positive for Metallo-β-lactamase (MBL) and all of the isolates presented the toxA genes, and 19.1%,17%, 6.3% presented by algD, ndvB and tssC1 genes. Besides, the phylogenetic trees of the toxA and tssC1 gene isolates suggested a genotype that was closely aligned with others. Gene sequencing similarity revealed 99% identity with other isolates deposited in GenBank.

Conclusion

The occurrence of toxA was most prevalent. One isolate was recorded as a novel isolate in the global gene bank as a locally isolated strain from the city of Erbil that has never been identified in global isolates due to genetic variation.

Ceragenins and Ceragenin-Based Core-Shell Nanosystems as New Antibacterial Agents against Gram-Negative Rods Causing Nosocomial Infections

The growing number of infections caused by multidrug-resistant bacterial strains, limited treatment options, multi-species infections, high toxicity of the antibiotics used, and an increase in treatment costs are major challenges for modern medicine. To remedy this, scientists are looking for new antibiotics and treatment methods that will effectively eradicate bacteria while continually developing different resistance mechanisms. Ceragenins are a new group of antimicrobial agents synthesized based on molecular patterns that define the mechanism of antibacterial action of natural antibacterial peptides and steroid-polyamine conjugates such as squalamine. Since ceragenins have a broad spectrum of antimicrobial activity, with little recorded ability of bacteria to develop a resistance mechanism that can bridge their mechanism of action, there are high hopes that this group of molecules can give rise to a new family of drugs effective against bacteria resistant to currently used antibiotics. Experimental data suggests that core-shell nanosystems, in which ceragenins are presented to bacterial cells on metallic nanoparticles, may increase their antimicrobial potential and reduce their toxicity. However, studies should be conducted, among others, to assess potential long-term cytotoxicity and in vivo studies to confirm their activity and stability in animal models. Here, we summarized the current knowledge on ceragenins and ceragenin-containing nanoantibiotics as potential new tools against emerging Gram-negative rods associated with nosocomial infections.

Antibacterial effect of seven days exposure to ceftolozane-tazobactam as monotherapy and in combination with fosfomycin or tobramycin against Pseudomonas aeruginosa with ceftolozane-tazobactam MICs at or above 4 mg/l in an in vitro pharmacokinetic model

OBJECTIVES

To use a pre-clinical pharmacokinetic infection model to assess the antibacterial effect of ceftolozane/tazobactam alone or in combination with fosfomycin or tobramycin against Pseudomonas aeruginosa strains with MICs at or higher than the clinical breakpoint (MIC ≥ 4 mg/L).

METHODS

An in vitro model was used to assess changes in bacterial load and population profiles after exposure to mean human serum concentrations of ceftolozane/tazobactam associated with doses of 2 g/1 g q8h, fosfomycin concentrations associated with doses of 8 g q8h or tobramycin at doses of 7 mg/kg q24 h over 168 h.

RESULTS

Simulations of ceftolozane/tazobactam at 2 g/1 g q8h alone produced 3.5-4.5 log reductions in count by 6 h post drug exposure for strains with MIC ≤32 mg/L. The antibacterial effect over the first 24 h was related to ceftolozane/tazobactam MIC. There was subsequent regrowth with most strains to bacterial densities of >106 CFU/mL. Addition of either fosfomycin or tobramycin resulted in suppression of regrowth and in the case of tobramycin more rapid initial bacterial killing up to 6 h. These effects could not be related to either fosfomycin or tobramycin MICs. Changes in population profiles were noted with ceftolozane/tazobactam alone often after 96 h exposure but such changes were suppressed by fosfomycin and almost abolished by the addition of tobramycin.

CONCLUSIONS

The addition of either fosfomycin or tobramycin to ceftolozane/tazobactam at simulated human clinically observed concentrations reduced P. aeruginosa bacterial loads and the risk of resistance to ceftolozane/tazobactam when strains had ceftolozane/tazobactam MIC values at or above the clinical breakpoint.

Drug combinations for inhalation: Current products and future development addressing disease control and patient compliance

Pulmonary delivery is an alternative route of administration with numerous advantages over conventional routes of administration. It provides low enzymatic exposure, fewer systemic side effects, no first-pass metabolism, and concentrated drug amounts at the site of the disease, making it an ideal route for the treatment of pulmonary diseases. Owing to the thin alveolar-capillary barrier, and large surface area that facilitates rapid absorption to the bloodstream in the lung, systemic delivery can be achieved as well. Administration of multiple drugs at one time became urgent to control chronic pulmonary diseases such as asthma and COPD, thus, development of drug combinations was proposed. Administration of medications with variable dosages from different inhalers leads to overburdening the patient and may cause low therapeutic intervention. Therefore, products that contain combined drugs to be delivered via a single inhaler have been developed to improve patient compliance, reduce different dose regimens, achieve higher disease control, and boost therapeutic effectiveness in some cases. This comprehensive review aimed to highlight the growth of drug combinations by inhalation over time, obstacles and challenges, and the possible progress to broaden the current options or to cover new indications in the future. Moreover, various pharmaceutical technologies in terms of formulation and device in correlation with inhaled combinations were discussed in this review. Hence, inhaled combination therapy is driven by the need to maintain and improve the quality of life for patients with chronic respiratory diseases; promoting drug combinations by inhalation to a higher level is a necessity.

Clinical predictors of mortality in patients with pseudomonas aeruginosa infection

BACKGROUND

Infections caused by Pseudomonas aeruginosa are difficult to treat with a significant cost and burden. In Lebanon, P. aeruginosa is one of the most common organisms in ventilator-associated pneumonia (VAP). P. aeruginosa has developed widespread resistance to multiple antimicrobial agents such as fluoroquinolones and carbapenems. We aimed at identifying risk factors associated for P. aeruginosa infections as well as identifying independent risk factors for developing septic shock and in-hospital mortality.

METHODS

We used a cross-sectional study design where we included patients with documented P. aeruginosa cultures who developed an infection after obtaining written consent. Two multivariable regression models were used to determine independent predictors of septic shock and mortality.

RESULTS

During the observed period of 30 months 196 patients were recruited. The most common predisposing factor was antibiotic use for more than 48 hours within 30 days (55%). The prevalence of multi-drug resistant (MDR) P. aeruginosa was 10%. The strongest predictors of mortality were steroid use (aOR = 3.4), respiratory failure (aOR = 7.3), identified respiratory cultures (aOR = 6.0), malignancy (aOR = 9.8), septic shock (aOR = 18.6), and hemodialysis (aOR = 30.9).

CONCLUSION

Understanding resistance patterns and risk factors associated with mortality is crucial to personalize treatment based on risk level and to decrease the emerging threat of antimicrobial resistance.

In Vitro and In Vivo Effect of Amikacin and Imipenem Combinations against Multidrug-Resistant E. coli

Introduction: The emergence of multidrug-resistant (MDR) E. coli has developed worldwide; therefore, the use of antibiotic combinations may be an effective strategy to target resistant bacteria and fight life-threatening infections. The current study was performed to evaluate the in vitro and in vivo efficacy of amikacin and imipenem alone and in combination against multidrug-resistant E. coli. Methods: The combination treatment was assessed in vitro using a checkerboard technique and time-killing curve and in vivo using a peritonitis mouse model. In resistant isolates, conventional PCR and quantitative real-time PCR techniques were used to detect the resistant genes of Metallo-β-lactamase gene Imipenemase (bla-_IMP) and aminoglycoside 6′-N-acetyltransferase (aac (6′)-Ib). Scanning electron microscopy was used to detect the morphological changes in the resistant isolates after treatment with each drug alone and in combination. In vitro and in vivo studies showed a synergistic effect using the tested antibiotic combinations, showing fractional inhibitory concentration indices (FICIs) of ≤0.5. Regarding the in vivo study, combination therapy indicated a bactericidal effect after 24 h. E. coli isolates harboring the resistant genes Metallo-β-lactamase gene Imipenemase (bla-_IMP) and aminoglycoside 6′-N-acetyltransferase (aac (6′)-Ib) represented 80% and 66.7%, respectively, which were mainly isolated from wound infections. The lowest effect on Metallo-β-lactamase gene Imipenemase (bla-_IMP) and aminoglycoside 6′-N-acetyltransferase (aac (6′)-Ib) gene expression was shown in the presence of 0.25 × MIC of imipenem and 0.5 × MIC of amikacin. The scanning electron microscopy showed cell shrinkage and disruption in the outer membrane of E. coli in the presence of the antibiotic combination. Amikacin and imipenem combination can be expected to be effective in the treatment and control of serious infections caused by multidrug-resistant (MDR) E. coli and the reduction in bacterial resistance emergence.

Antibacterial Activity of Metallic Nanoparticles against Multidrug-Resistant Pathogens Isolated from Environmental Samples: Nanoparticles/Antibiotic Combination Therapy and Cytotoxicity Study

Multidrug-resistant organisms have increased the prevalence of infectious diseases and have become the leading source of death globally. The adverse effects associated with conventional antibiotics cannot be underestimated, and as a result, the quest for antibacterial agents has received great attention over the years. Therefore, the current research was designed to synthesize and examine the antibacterial properties of two metallic nanoparticles, silver nanoparticles (AgNPs) and zinc oxide nanoparticles (ZnONPs), as well as their antibiotic combination therapy against multidrug-resistant bacteria. AgNPs and ZnONPs were synthesized by the coprecipitation method and characterized. Thereafter, their antibacterial activity against multidrug-resistant bacteria was investigated using the microdilution technique. Subsequently, the interactions between the synthesized nanoparticles and antibiotics were evaluated by checkerboard assay. Time-kill assays were carried out to assess bacteriostatic or bactericidal effects, and the cytotoxicity study was carried out by MTT assay. The SEM analysis of AgNPs and ZnONPs were spherical with an average size of 21.03 and 43.37 nm, respectively. FTIR analysis showed the characteristics of the metal-oxygen vibrational band for both materials around 450 cm-1, which indicated the successful synthesis of these antibacterial agents. The EDX characterization revealed Zn and O with 77.89% and 18.24% abundance in ZnONPs and Ag with 95.65% abundance in AgNPs. UV-vis absorption spectra of AgNPs was obtained around 400 nm. ZnONPs showed a moderate antibacterial effect against Enterococcus species with a MIC range of 2.5-5 mg/mL, while AgNPs demonstrated a strong antibacterial effect against the tested bacterial strains with a MIC range of 0.078-0.039 mg/mL. The ZnONPs were found to be cytotoxic against Vero cell lines at the tested concentrations, whereas AgNPs had no cytotoxic effect at lower concentrations. Their combination activities showed synergetic and additive effects. These findings revealed that these synthesized materials could serve as alternate antibacterial agents against multidrug-resistant Acinetobacter baumanni and Enterococcus species.

Phage delivered CRISPR-Cas system to combat multidrug-resistant pathogens in gut microbiome

The Host-microbiome interactions that exist inside the gut microbiota operate in a synergistic and abnormal manner. Additionally, the normal homeostasis and functioning of gut microbiota are frequently disrupted by the intervention of Multi-Drug Resistant (MDR) pathogens. CRISPR-Cas (CRISPR-associated protein with clustered regularly interspersed short palindromic repeats) recognized as a prokaryotic immune system has emerged as an effective genome-editing tool to edit and delete specific microbial genes for the expulsion of bacteria through bactericidal action. In this review, we demonstrate many functioning CRISPR-Cas systems against the anti-microbial resistance of multiple pathogens, which infiltrate the gastrointestinal tract. Moreover, we discuss the advancement in the development of a phage-delivered CRISPR-Cas system for killing a gut MDR pathogen. We also discuss a combinatorial approach to use bacteriophage as a delivery system for the CRISPR-Cas gene for targeting a pathogenic community in the gut microbiome to resensitize the drug sensitivity. Finally, we discuss engineered phage as a plausible potential option for the CRISPR-Cas system for pathogenic killing and improvement of the efficacy of the system.