Assessment of antibiotic resistance in Klebsiella pneumoniae exposed to sequential in vitro antibiotic treatments. Issue 1 (December 2016)

• Record Type: Journal Article
• Authors: Kim, Jeongjin; Jo, Ara; Chukeatirote, Ekachai; Ahn, Juhee
• Is Part Of: Annals of clinical microbiology and antimicrobials. Volume 15:Issue 1(2016)
• Page Start: 1
• Page End: 7
• Publication Date: 2016-12
• Subjects: β-Lactamase -- Efflux pump system -- Meropenem -- Ciprofloxacin -- Antibiotic resistance; Medical microbiology -- Periodicals; Anti-infective agents -- Periodicals; 616.9041
• DOI: 10.1186/s12941-016-0173-x
• Languages: English
• ISSNs: 1476-0711

Abstract

Abstract Background Bacteria treated with different classes of antibiotics exhibit changes in susceptibility to successive antibiotic treatments. This study was designed to evaluate the influence of sequential antibiotic treatments on the development of antibiotic resistance inKlebsiella pneumoniae associated with β-lactamase and efflux pump activities. Methods The antibiotic susceptibility, β-lactamase activity, and efflux activity were determined inK .pneumoniae grown at 37 °C by adding initial (0 h) and second antibiotics (8 or 12 h). Treatments include control (CON; no first and second antibiotic addition), no initial antibiotic addition followed by 1 MIC ciprofloxacin addition (CON-CIP), no initial antibiotic addition followed by 1 MIC meropenem addition (CON-MER), initial 1/4 MIC ciprofloxacin addition followed by no antibiotic addition (1/4CIP-CON), initial 1/4 MIC ciprofloxacin addition followed by 1 MIC ciprofloxacin addition (1/4CIP-CIP), and initial 1/4 MIC ciprofloxacin addition followed by 1 MIC meropenem addition (1/4CIP-MER). Results Compared to the CON, the initial addition of 1/4 MIC ciprofloxacin inhibited the growth ofK .pneumoniae throughout the incubation period. The ciprofloxacin treatments (CON-CIP and 1/4CIP-CIP) showed significant reduction in the number ofK .pneumoniae cells compared to meropenem (CON-MER and 1/4CIP-MER). The 1/4CIP-CIP achieved a further 1 log reduction ofK .pneumoniae, when compared to the 1/4CIP-CON and 1/CIP-MER. The increase in sensitivity ofK .pneumoniae to cefotaxime, kanamycin, levofloxacin, nalidixic acid was observed for CON-CIP. Noticeable cross-resistance pattern was observed at the 1/4CIP-CIP, showing the increased resistance ofK .pneumoniae to chloramphenicol, ciprofloxacin, kanamycin, levofloxacin, nalidixic acid norfloxacin, sulphamethoxazole/trimethoprim, and tetracycline. The levels of β-lactamase activities were estimated to be 8.4 μmol/min/ml for CON, 7.7 μmol/min/ml for 1/4CIP-CON and as low as 2.9 μmol/min/ml for CON-CIP. Compared to the absence of phenylalanine-arginine-β-naphthylamide (PAβN), the fluorescence intensity of EtBr was increased inK .pneumoniae cells treated at the CON, CON-CIP, and CON-MER in the presence of PAβN. However, the efflux pump activity remained inK .pneumoniae cells treated at the 1/CIP, 1/CIP–CIP, and 1/CIP-MER in the presence of PAβN. Conclusion The results suggest that the pre-exposed antibiotic history, treatment order, and concentrations influenced the development of multiple antibiotic resistant associated with β-lactamase and efflux pump activities. This study highlights the importance of antibiotic treatment conditions, which would be taken into consideration when new antibiotic strategy is designed to prevent antibiotic resistance.