ABSTRACT
BACKGROUND: Acinetobacter baumannii is challenging the healthcare community as the cause of a wide range of untreatable infections. New targets need to be explored for the development of therapeutics. METHODS: The potassium-dependent protein (Kdp) system was investigated via bioinformatics and genetic tools. An isogenic mutant was constructed in kdpE and complemented in trans Gene expression and the ability to grow under potassium-limited conditions were investigated. Finally, the role of KdpE in virulence was examined in the murine pneumonia model. RESULTS: The A. baumannii Kdp system has a distinct arrangement and is well conserved among A. baumannii strains. The genes encoding the 5 members of the system are transcriptionally linked. kdpE is upregulated >70-fold under potassium-limited conditions. The ΔkdpE mutant showed a significant growth defect under potassium-limited conditions and in the colonization of mice lungs. These defects could be restored upon introducing kdpE on a multiple-copy plasmid. Proteomic analyses indicated that KdpE could be regulating several proteins with potential involvement in pathogenesis. CONCLUSIONS: For the first time, A. baumannii KdpE is shown to be crucial to pneumonia onset, and targeting this system can be a viable approach to treating these fatal infections.
Subject(s)
Acinetobacter Infections/microbiology , Acinetobacter baumannii/physiology , Adaptation, Physiological , Pneumonia, Bacterial/microbiology , Potassium/metabolism , Acinetobacter baumannii/isolation & purification , Acinetobacter baumannii/metabolism , Animals , Bacterial Proteins/genetics , Disease Models, Animal , Gene Deletion , Genetic Complementation Test , Male , Mice, Inbred C57BL , Transcription Factors/genetics , Virulence , Virulence Factors/geneticsABSTRACT
BACKGROUND: Resistant Pseudomonas aeruginosa is a serious concern for antimicrobial therapy, as the common isolates exhibit variable grades of resistance, involving beta-lactamase enzymes, beside native defense mechanisms. OBJECTIVES: The present study was designed to determine the occurrence of Metallo-ß- Lactamases (MBL) and Amp C harboring P. aeruginosa isolates from Suez Canal university hospital in Ismailia, Egypt. METHODS: A total of 147 P. aeruginosa isolates, recovered from 311 patients during a 10-month period, were collected between May 2013 and February 2014; the isolates were collected from urine, wound and sputum. Minimum inhibitory concentration (MIC) determined by agar dilution methods was ≥2 µg/mL for meropenem and imipenem. Identification of P. aeruginosa was confirmed using API 20NE. Metallo-ß- Lactamases and Amp C were detected based on different phenotypic methods. RESULTS: Overall, 26.5% of P. aeruginosa isolates (39/147) were carbapenem resistant isolates. Furthermore, 64.1% (25/39) were MBL producers, these isolates were screened by the combined disc and disc diffusion methods to determine the ability of MBL production. Both MBL and Amp C harbored P. aeruginosa isolates were 28% (7/25). Sixty-four percent of P. aeruginosa isolates were multidrug resistant (MDR) (16/25). The sensitivity toward polymyxin, imipenem, norfloxacin, piperacillin-tazobactam and gentamicin was 99%, 91%, 88%, 82% and 78%, respectively. The resistance rate towards cefotaxime, ceftazidime, cefepime, aztreonam and meropenem was 98.6%, 86%, 71.4%, 34% and 30%, respectively. CONCLUSIONS: Multidrug resistance was significantly associated with MBL production in P. aeruginosa. Early detection of MBL-producing P. aeruginosa and hospital antibiotic policy prescription helps proper antimicrobial therapy and avoidance of dissemination of these multidrug resistance isolates.
