Effectiveness of antibacterial agents against cell-invading bacteria such as Streptococcus pyogenes and Haemophilus influenzae

Solar Photodegradation of a Novel des-F(6)-Fluoroquinolone, Garenoxacin, and Ecotoxicity of Its Phototransformation Products

Garenoxacin (GRNX) is a novel des-F(6)-fluoroquinolone on the horizon; thus, its fate and risk in the aquatic environment deserve attention. This study systematically investigated, for the first time, the phototransformation of GRNX under simulated and natural sunlight and assessed the ecotoxicity of its photodegradation products. Phototransformation of GRNX was observed to depend strongly on its ionization state, with direct photolysis and self-sensitized photolysis having comparable contributions for the cationic and zwitterionic species, while the latter dominated for the anionic species. Singlet oxygen generated via the self-sensitized photolysis of GRNX was the major reactive oxygen species in its photodegradation. Phototransformation of GRNX in different ionization states followed distinct pathways, with defluorination of the difluoromethyl group occurring only for the zwitterionic and anionic species. GRNX photodegradation in natural water could be described by a simple kinetic model based on the measured steady-state concentrations of 1O2 and ·OH. Toxicity tests with Vibrio fischeri and Chlorella vulgaris consistently indicate that the generation of hydroxylation and decarboxylation products during photodegradation of GRNX increased the acute toxicity. These findings not only provide insights into the fate of GRNX in sunlit surface water but also reveal the potentially significant risk of its photodegradation products to the aquatic ecosystem.

Bactericidal effect of lascufloxacin on HEp-2 cell-internalized group A Streptococcus

INTRODUCTION

Although amoxicillin (AMPC) is recommended as first-line therapy for acute pharyngotonsillitis caused by group A streptococci (GAS), it often fails to eradicate infections. Internalization and subsequent intracellular survival of GAS are considered major mechanisms for penicillin therapeutic failure. It is, therefore, desirable to administer drugs that exert bactericidal effects on extracellular and intracellular GAS. In this study, we aim to investigate the bactericidal effects of lascufloxacin (LSFX) on internalized GAS in HEp-2 cells.

MATERIALS AND METHODS

The GAS strain M1 and clinical isolate strain #2 were used in this study. Following treatment of GAS-infected human pharyngeal carcinoma epithelial HEp-2 cells with LSFX or AMPC, internalized GAS cells were recovered. The concentrations of LSFX and AMPC were equivalent to 1 × and 2 × MIC for strain M1. Culture medium was used as a control. Time-lapse and fluorescence images of GAS invading HEp-2 cell were obtained. LIVE/DEAD fluorescence staining was used to confirm the viability of internalized GAS.

RESULTS

LSFX significantly reduced the number of cell-internalized M1 and #2 GAS strains compared to the control (p < 0.01) in a dose-dependent manner. However, AMPC did not reduce this in both strains. Both live and dead intracellular GAS were confirmed in HEp-2 cells exposed to LSFX. In contrast, intracellular GAS survived in HEp-2 cells exposed to AMPC and in the control.

CONCLUSION

LSFX elicits significant bactericidal effects on cell-internalized GAS, hence it may represent a potent therapeutic option for patients with acute pharyngotonsillitis in whom AMPC treatment has failed.

Correlation between Drug Resistance of Klebsiella Pneumonia and Antimicrobial Drug Usage

Objective. To assess the correlation between the drug resistance of Klebsiella pneumoniae and antimicrobial drug usage. Methods. The drug resistance rate of Klebsiella pneumoniae and the antimicrobial drug dosage of inpatients admitted to The Second Affiliated Hospital of Wannan Medical College from January 2016 to December 2020 were retrospectively recorded, and their correlation was analyzed using the Pearson method. Results. There are 6493 strains of Gram-negative bacteria, including 1272 strains of Klebsiella pneumoniae, ranking first in respiratory medicine. Klebsiella pneumoniae showed an overall increasing trend in resistance to piperacillin/tazobactam and ampicillin/sulbactam and a high resistance to aztreonam, ceftazidime, and ciprofloxacin (all P < 0.05). The top 3 antimicrobial drugs used in 2016-2020 were β-lactams, quinolones, and macrolides. The rates of resistance to piperacillin/tazobactam, cefoperazone/sulbactam, and ampicillin/sulbactam were highly positively correlated with the use of β-lactams. The use of carbapenems and glycopeptides was negatively correlated with the resistance to ciprofloxacin, and the resistance to ceftazidime had a high positive correlation with the use of glycopeptides and carbapenems. Conclusion. The use of antimicrobial drugs is correlated with the resistance rate of Klebsiella pneumoniae. To reduce bacterial drug resistance, the rational use of antimicrobial drugs requires joint control through multiple departments to improve the clinical use of antimicrobial drugs and improve in-hospital control.