In vitro study of antimicrobial activity on Klebsiella Pneumoniae biofilms in endotracheal tubes

Abstract

Effective treatment approaches for biofilms in endotracheal tubes (ETTs) are lacking. In this study, we evaluated the in vitro effects of five antimicrobials against biofilms formed by Klebsiella pneumoniae in ETTs. K. pneumoniae was added to minimal mucin medium prior to inoculation in microtiter plates containing ETT fragments. Biofilm susceptibility was assessed by crystal violet staining. At 24 h, the antimicrobials significantly reduced biofilm formation. At 48 h, all of the antimicrobial agents exhibited significant reductions in biofilm formation, even at concentrations above the minimum inhibitory concentration (MIC). Tigecycline and fosfomycin showed the greatest inhibition capacity, with good activity at concentrations twofold greater than the MIC. K. pneumoniae exhibited excellent biofilm formation ability, with formation in the first 24 h and significantly reduced antimicrobial activity. These results contribute to the establishment of new antibiotic breakpoints for the adequate management of infections associated with biofilm formation.

Abbreviations
ETT	=	Endotracheal tube
MIC	=	Minimum inhibitory concentration
MBIC	=	Minimum biofilm inhibitory concentration
OD	=	Optical density
PBS	=	Phosphate-buffered saline
VAP	=	Ventilator-associated pneumonia

Keywords:

• Biofilm
• critical care
• endotracheal tube
• ventilator-associated pneumonia
• tigecycline
• klebsiella

Acknowledgments

Dr. Jesús Ruiz acknowledges the support of Instituto de Investigación Sanitaria La Fe (Spain). Dr. Carmen Amaro acknowledges the support of MINECO (Ministerio de Economía Industria y Competitividad, Spain) (Project AGL2017--87723) and GVA (Generalitat Valenciana) (Project AICO2018-123).

Disclosure statement

The authors report no conflict of interest.

Additional information

Notes on contributors

Jesus Ruiz

Dra. Paula Ramirez, Dr. Jesús Ruiz, Dra. Mónica Gordon, Dra. Esther Villarreal and Dr. Álvaro Castellanos are currently serving as a faculty member at the Department Intensive Care Unit in Hospital La Fe, Spain. They are all part of a research team, which, led by Dr. Ramirez, has spent years studying the effect of bacterial biofilms on the clinical response to antibiotics, as well as the study of the pharmacokinetics of antimicrobials and predicting biomarkers of infection response, having all completed their PhD studies in this field.

Eva Sanjuan

Dra. Carmen Amaro and Dra. Eva San Juán are now working as faculty member of department of microbiology, parasitology and immunology, at Valencia University, Spain. They are interested in molecular investigation of virulence factors of diverses bacterial species and in the field of metagenomics and transcriptomics.

Carmen Amaro

Dra. Carmen Amaro and Dra. Eva San Juán are now working as faculty member of department of microbiology, parasitology and immunology, at Valencia University, Spain. They are interested in molecular investigation of virulence factors of diverses bacterial species and in the field of metagenomics and transcriptomics.

Monica Gordon

Dra. Paula Ramirez, Dr. Jesús Ruiz, Dra. Mónica Gordon, Dra. Esther Villarreal and Dr. Álvaro Castellanos are currently serving as a faculty member at the Department Intensive Care Unit in Hospital La Fe, Spain. They are all part of a research team, which, led by Dr. Ramirez, has spent years studying the effect of bacterial biofilms on the clinical response to antibiotics, as well as the study of the pharmacokinetics of antimicrobials and predicting biomarkers of infection response, having all completed their PhD studies in this field.

Esther Villarreal

Dra. Paula Ramirez, Dr. Jesús Ruiz, Dra. Mónica Gordon, Dra. Esther Villarreal and Dr. Álvaro Castellanos are currently serving as a faculty member at the Department Intensive Care Unit in Hospital La Fe, Spain. They are all part of a research team, which, led by Dr. Ramirez, has spent years studying the effect of bacterial biofilms on the clinical response to antibiotics, as well as the study of the pharmacokinetics of antimicrobials and predicting biomarkers of infection response, having all completed their PhD studies in this field.

Álvaro Castellanos-Ortega

Dra. Paula Ramirez, Dr. Jesús Ruiz, Dra. Mónica Gordon, Dra. Esther Villarreal and Dr. Álvaro Castellanos are currently serving as a faculty member at the Department Intensive Care Unit in Hospital La Fe, Spain. They are all part of a research team, which, led by Dr. Ramirez, has spent years studying the effect of bacterial biofilms on the clinical response to antibiotics, as well as the study of the pharmacokinetics of antimicrobials and predicting biomarkers of infection response, having all completed their PhD studies in this field.

Paula Ramirez

Dra. Paula Ramirez, Dr. Jesús Ruiz, Dra. Mónica Gordon, Dra. Esther Villarreal and Dr. Álvaro Castellanos are currently serving as a faculty member at the Department Intensive Care Unit in Hospital La Fe, Spain. They are all part of a research team, which, led by Dr. Ramirez, has spent years studying the effect of bacterial biofilms on the clinical response to antibiotics, as well as the study of the pharmacokinetics of antimicrobials and predicting biomarkers of infection response, having all completed their PhD studies in this field.