Treatment for patients with multidrug resistant Acinetobacter baumannii pulmonary infection

Study on the inhibition activity and mechanism of Tanreqing against Klebsiella pneumoniae biofilm formation in vitro and in vivo

Objective

To evaluate the antibacterial effect of Tanreqing (TRQ) against K. pneumoniae and its inhibition activity on bacterial biofilm formation in vitro and in vivo, and to explore the mechanism of the inhibitory effects of TRQ on K. pneumoniae biofilm formation.

Methods

An in vitro biofilm model of K. pneumoniae was established, and the impact of TRQ on biofilm formation was evaluated using crystal violet staining and scanning electron microscopy (SEM). Furthermore, the clearance effect of TRQ against K. pneumoniae in the biofilm was assessed using the viable plate counting method; q-RT PCR was used to evaluate the inhibitory effect of different concentrations of TRQ on the expression of biofilm-related genes in Klebsiella pneumoniae; The activity of quorum sensing signal molecule AI-2 was detected by Vibrio harveyi bioluminescence assay; Meanwhile, a guinea pig lung infection model of Klebsiella pneumoniae was constructed, and after treated with drugs, pathological analysis of lung tissue and determination of bacterial load in lung tissue were performed. The treatment groups included TRQ group, imipenem(IPM) group, TRQ+IPM group, and sterile saline group as the control.

Results

The formation of K. pneumoniae biofilm was significantly inhibited by TRQ in vitro experiments. Furthermore, when combined with IPM, the clearance of K. pneumoniae in the biofilm was notably increased compared to the TRQ group and IPM group alone. q-RT PCR analysis revealed that TRQ down-regulated the expression of genes related to biofilm formation in K. pneumoniae, specifically luxS, wbbm, wzm, and lsrK, and also inhibited the activity of AI-2 molecules in the bacterium. In vivo experiments demonstrated that TRQ effectively treated guinea pig lung infections, resulting in reduced lung inflammation. Additionally, when combined with IPM, there was a significant reduction in the bacterial load in lung tissue.

Conclusion

TRQ as a potential therapeutic agent plays a great role in the treatment of K. pneumoniae infections, particularly in combination with conventional antibiotics. And TRQ can enhanced the clearance effect on the bacterium by inhibiting the K. pneumoniae biofilm formation, which provided experimental evidence in support of clinical treatment of TRQ against K. pneumoniae infections.

Efficacy of Cefoperazone Sulbactam in Patients with Acinetobacter Infections: A Systematic Review of the Literature

Introduction: Acinetobacter baumannii (AB) is a multidrug-resistant pathogen commonly associated with nosocomial infections. The resistance profile and ability to produce biofilm make it a complicated organism to treat effectively. Cefoperazone sulbactam (CS) is commonly used to treat AB, but the associated data are scarce. Methods: We conducted a systematic review of articles downloaded from Cochrane, Embase, PubMed, Scopus, and Web of Science (through June 2022) to study the efficacy of CS in treating AB infections. Our review evaluated patients treated with CS alone and CS in combination with other antibiotics separately. The following outcomes were studied: clinical cure, microbiological cure, and mortality from any cause. Results: We included 16 studies where CS was used for the treatment of AB infections. This included 11 studies where CS was used alone and 10 studies where CS was used in combination. The outcomes were similar in both groups. We found that the pooled clinical cure, microbiological cure, and mortality with CS alone for AB were 70%, 44%, and 20%, respectively. The pooled clinical cure, microbiological cure, and mortality when CS was used in combination with other antibiotics were 72%, 43%, and 21%, respectively. Conclusions: CS alone or in combination needs to be further explored for the treatment of AB infections. There is a need for randomized controlled trials with comparator drugs to evaluate the drug’s effectiveness.

The frequency of efflux pump genes expression in Acinetobacter baumannii isolates from pulmonary secretions

Acinetobacter baumannii is an important opportunistic pathogen, and the cause of nosocomial infections worldwide in recent decades. Efflux pumps are considered as the important causes of multidrug resistance of A. baumannii. The aim of this study was to determine the frequency of efflux pump genes, and evaluate the antibiotic effect of Tigecycline on the expression of adeB gene in isolates of multidrug-resistant. A. baumannii. 70 isolates of A. baumannii were collected and confirmed by biochemical and molecular tests. Antibiotic resistance (Ciprofloxacin, Trimethoprim-sulfamethoxazole, and Tigecycline) was performed based on the minimum inhibitory concentration (MIC) method. Then, the effect of Carbonyl cyanide m-chlorophenyl hydrazone inhibitor (CCCP) on isolates was investigated and the frequency of adeB, adeG, adeJ and abeM genes were examined by PCR for isolates with reduced in MIC titer. Also, the antibiotic effect of Tigecycline on adeB gene expression in A. baumannii isolates was analyzed by Real-Time PCR. The antibiotic resistance for Ciprofloxacin, Trimethoprim-sulfamethoxazole, and Tigecycline was 97.1%, 95.8% and 37.2%, respectively. Following CCCP inhibitor use, the MIC titer had a decrease in MIC titer containing CCCP inhibitor was 64.3% for Ciprofloxacin, 51.5% for Trimethoprim-sulfamethoxazole and 50% for Tigecycline. The frequencies of genes associated with adeB, adeG, adeJ and abeM efflux pump were 100%, 92.8%, 86% and 98.5%, respectively. Real-Time PCR results showed a correlation between the antibiotic effects of Tigecycline on adeB gene expression. The antibiotic resistance of the isolates was relatively high. The isolates were resistant to Ciprofloxacin and Trimethoprim-sulfamethoxazole antibiotics, while more sensitive to Tigecycline. Also, efflux pump genes, which are the antibiotic resistance factors of A. baumannii, are frequently high in the isolates but it seems that isolates use other effluxe pumps than RND family to exit tigecycline.

The frequencies of genes associated with adeB, adeG, adeJ and abeM efflux pump were 100%, 92.8%, 86% and 98.5%, respectively.

Real-Time PCR results showed a correlation between the antibiotic effects of Tigecycline on adeB gene expression. The antibiotic resistance of the isolates was relatively high.

Also, efflux pump genes, which are the antibiotic resistance factors of A. baumannii, are frequently high in the isolates but it seems that isolates use other effluxe pumps than RND family to exit tigecycline.

Co-spray-dried poly-L-lysine with L-leucine as dry powder inhalations for the treatment of pulmonary infection: Moisture-resistance and desirable aerosolization performance

Poly-L-lysine (PLL) is a promising candidate for the treatment of pulmonary infection with lower occurrence of drug-resistance due to its unique antibacterial mechanisms. Dry powder inhalations (DPIs) are considered as the first choice for formulating PLL to treat pulmonary infection on account of direct delivery and satisfactory stability. However, hygroscopicity of PLL limited its therapeutic effect on pulmonary infection when PLL developed into DPIs. The hygroscopicity caused two obstacles including the low drug deposition in the lower respiratory tract and undesirable aerosolization performance deterioration. In this study, PLL was co-spray-dried with L-leucine (LL) to achieve moisture-resistance and desirable aerosolization performance. The ratio of PLL and LL was optimized to obtain particles with different morphology, hygroscopicity and aerodynamic properties. The obtained PLL DPIs were suitable for inhalation with a corrugated surface formed by hydrophobic LL. The anti-hygroscopicity, aerosolization performance and rheological properties of P₂ DPIs were optimal when PLL:LL = 85:15. The DPIs particles were stable after being stored at high relative humidity (60 ± 5%), and their superiority in treating pulmonary infections was also proved by in vitro and in vivo experiments. The established PLL DPIs were proved to be a feasible and desirable approach to treat pulmonary infections.

Photodynamic antimicrobial chemotherapy with the novel amino acid-porphyrin conjugate 4I: In vitro and in vivo studies

Photodynamic antimicrobial chemotherapy (PACT), as a novel and effective therapeutic modality to eradicate drug resistant bacteria without provoking multidrug resistance, has attracted increasing attention. This study examined the antimicrobial efficacy of the novel cationic amino acid-porphyrin conjugate 4I with four lysine groups against two different clinical isolated strains (drug sensitive and multidrug resistant) of the Acinetobacter baumannii species and its toxicity on murine dermal fibroblasts in vitro, as well as the therapeutic effect of PACT on acute, potentially lethal multidrug resistant strain excisional wound infections in vivo. The PACT protocol exposed 4I to illumination, exhibiting high antimicrobial efficacy on two different strains due to a high yield of reactive oxygen species (ROS) and non-selectivity to microorganisms. The photoinactivation effects of 4I against two different strains were dose-dependent. At 3.9 μM and 7.8 μM, PACT induced 6 log units of inactivation of sensitive and multidrug resistant strains. In contrast, 4I alone and illumination alone treatments had no visibly antimicrobial effect. Moreover, cytotoxicity tests revealed the great safety of the photosensitizer 4I in mice. In the in vivo study, we found 4I-mediated PACT was not only able to kill bacteria but also accelerated wound recovery. Compared with non-treated mice, over 2.89 log reduction of multidrug resistant Acinetobacter baumannii strain was reached in PACT treat mice at 24 h post-treatment. These results imply that 4I-mediated PACT therapy is an effective and safe alternative to conventional antibiotic therapy and has clinical potential for superficial drug-resistant bacterial infections.

Antibiotic Trends Amid Multidrug-Resistant Gram-Negative Infections in Intensive Care Units

Isolates from ICUs most commonly find multidrug-resistant (MDR) gram-negative bacteria. The purpose of this article is to discuss the significant impact MDR gram-negative infections are having on ICUs, the threat on health and mortality, and effective and new approaches aimed to combat MDR gram-negative infections in critically ill populations. Inappropriate antibiotic therapies for suspected or documented infections are the leading cause of the emergence of bacterial resistance. A variety of strategies are aimed at combatting this international burden via antibiotic stewardship programs. Studies are demonstrating promise against the virulence MDR gram-negative infections have posed.

Clinical response and outcome of pneumonia due to multi-drug resistant Acinetobacter baumannii in critically ill patients

BACKGROUND AND OBJECTIVES

The frequency of multi-drug resistant Acinetobacter spp. infections is increasing in Iran. Considering availability of limited therapeutic options, clinical response and outcome of ventilator-associated pneumonia due to multi-drug resistant A.baumannii were evaluated in critically ill patients.

MATERIALS AND METHODS

In this prospective study, 29 patients with carbapenem resistance A. baumannii ventilator-associated pneumonia were enrolled. Endotracheal aspirate specimens were analyzed according to the clinical and laboratory standard institute instructions in the hospital's microbiology laboratory. Demographics, clinical, microbiological and laboratory findings were collected for each patient during the treatment course. Therapeutic empirical regimen, change in antibiotic regimen following receiving antibiogram results, clinical and microbiological responses, duration of ICU stay and outcome were collected for each recruited individual.

RESULTS

All of A. baumanii isolates were resistant to pipracillin-tazobactam, ceftriaxon, amikacin and ciprofloxacin. The resistance rate of A. baumanii species was 41.4% for ampicillin/sulbactabm and 93.1% for meropenem. Patients received either meropenem/colistin (51.7%) or meropenem/ampicillin-sulbactam (48.3%) as the treatment regimens based on the antimicrobial susceptibility patterns of isolates. Ventilator-associated pneumonia clinical response, improvement and failure achieved in 15 (51.7%), 8 (27.6%) and 6 (20.7%) of the patients respectively. Microbiological eradication and intermediate status were observed in 9/29 (31%) and 11/29 (37.9%) of patients, respectively.

CONCLUSION

The antibiotic regimens showed comparable efficacy in treatment of VAP due to MDR A. baumannii but mortality rate was high. Considering widespread and high mortality rates associated with MDR infections, applying infection control and antibiotic stewardship programs in hospitals are essential.