In vitro activity of aminoglycosides against clinical isolates of Acinetobacter baumannii complex and other nonfermentative Gram-negative bacilli causing healthcare-associated bloodstream infections in Taiwan
Abstract:Background/Purpose: Aminoglycosides possess in vitro activity against aerobic and facultative Gram-negative bacilli. However, nationwide surveillance on susceptibility data of Acinetobacter baumannii complex and Pseudomonas aeruginosa to aminoglycosides was limited, and aminoglycoside resistance has emerged in the past decade. We study the in vitro susceptibility of A. baumannii complex and other nonfermentative Gram-negative bacilli (NFGNB) to aminoglycosides. Methods: A total of 378 NFGNB blood isolates caus… Show more
“…Our study revealed that colistin (92%) and gentamicin (85%) were the most active antibiotics, whereas, in earlier studies, the results of the spectrum rates of colistin (60%) and trimethoprim and sulfamethoxazole (46%) did not correlate with our studies [ 43 , 44 ]. Among the clinical isolates, A. baumannii was extremely resistant to two carbapenem drugs, meropenem (57%) and imipenem (53%), and these spectrum rates were not correlated with previous studies [ 45 ], indicating that the spectrum of the antimicrobial resistance profile may vary from place to place and nosocomial-associated pathogens.…”
Multidrug-resistant strains are frequent causes of nosocomial infections. The majority of nosocomial infections, particularly in critical care units (ICU), have been linked to A. baumannii, which has major clinical significance. The current paper attempts to identify the potential risk and prognosis factors for acquiring an infection due to A. baumannii compared to that of other nosocomial bacteria. In our study, we employed antibiotics generally prescribed for the initial course of treatment such as colistin, meropenem, amikacin, trimethoprime-sulfamethoxazole, levofloxacin, gentamicin, ciprofloxacin, and piperacillin-tazobactam. We found that the isolated A. baumannii were resistant at a high rate to meropenem, piperacillin–tazobactam, amikacin, levofloxacin, and ciprofloxacin, while they were partially susceptible to trimethoprim-sulfamethoxazole. Our study revealed that A. baumannii was most susceptible to gentamicin and colistin at 85.8% and 92.9%, respectively, whereas the combination of colistin and trimethoprim/sulfamethoxazole was 100% active. The patients were the primary source of infection with A. baumannii, followed by inanimate objects present in the ICU and hospital premises, and then the hospital staff who were taking care of the ICU patients. Gentamicin and colistin were the most sensitive antibiotics; of the 13 tested in total, the rate of drug resistance was above 50%. The very high rate of antibiotic resistance is alarming.
“…Our study revealed that colistin (92%) and gentamicin (85%) were the most active antibiotics, whereas, in earlier studies, the results of the spectrum rates of colistin (60%) and trimethoprim and sulfamethoxazole (46%) did not correlate with our studies [ 43 , 44 ]. Among the clinical isolates, A. baumannii was extremely resistant to two carbapenem drugs, meropenem (57%) and imipenem (53%), and these spectrum rates were not correlated with previous studies [ 45 ], indicating that the spectrum of the antimicrobial resistance profile may vary from place to place and nosocomial-associated pathogens.…”
Multidrug-resistant strains are frequent causes of nosocomial infections. The majority of nosocomial infections, particularly in critical care units (ICU), have been linked to A. baumannii, which has major clinical significance. The current paper attempts to identify the potential risk and prognosis factors for acquiring an infection due to A. baumannii compared to that of other nosocomial bacteria. In our study, we employed antibiotics generally prescribed for the initial course of treatment such as colistin, meropenem, amikacin, trimethoprime-sulfamethoxazole, levofloxacin, gentamicin, ciprofloxacin, and piperacillin-tazobactam. We found that the isolated A. baumannii were resistant at a high rate to meropenem, piperacillin–tazobactam, amikacin, levofloxacin, and ciprofloxacin, while they were partially susceptible to trimethoprim-sulfamethoxazole. Our study revealed that A. baumannii was most susceptible to gentamicin and colistin at 85.8% and 92.9%, respectively, whereas the combination of colistin and trimethoprim/sulfamethoxazole was 100% active. The patients were the primary source of infection with A. baumannii, followed by inanimate objects present in the ICU and hospital premises, and then the hospital staff who were taking care of the ICU patients. Gentamicin and colistin were the most sensitive antibiotics; of the 13 tested in total, the rate of drug resistance was above 50%. The very high rate of antibiotic resistance is alarming.
“…5 Pseudomonas aeruginosa is found to be less sensitive to amikacin (41.60%) and gentamycin (45.80%) as compared to another study conducted at Taiwan in which resistance for amikacin and gentamycin was 98% an 94% respectively. 6 There are few different mechanisms involved in drug resistance of Pseudomonas.…”
Background: Bacteremia caused by non-fermenting gram negative bacilli (NFGNB) is a serious infection which is associated with high morbidity and mortality. Identification of NFGNB and monitoring their susceptibility pattern are important for proper management of these infections. Aim: Scope of the present study is to characterize the NFGNB along with their antimicrobial sensitivity pattern among the patients coming to our hospital, a tertiary care center. Materials & Methods: A retrospective study was conducted to determine the NFGNB isolated from blood during the one-year study period. A total of 8223 Blood cultures were received in the laboratory which was processed by semi-automated technique in Bac-T Alert. Antibiotic susceptibility was performed by VITEK and Kirby Bauer methods and interpreted by CLSI guidelines. 102 isolates of NFGNB were obtained from the Blood culture. Results: Most commonly isolated organism is Acinetobacter species (47%) followed by Pseudomonas spp (27%) and Burkholderia spp(15.6%). Maximum isolates of Acinetobacter spp were sensitive to colistin (91.9%), cefoperazone-sulbactum (88.4%), Tigecycline (62.5%). Pseudomonas spp was sensitive to colistin (100%), ciprofloxacin (59%). Conclusion: Identification of NFGNB and monitoring their susceptibility patterns will help in proper management of infections caused by them.
“…Therefore, its involvement in cell wall breakage and leakage of cell components as shown here may be indirect. Gen is reported to be associated with the cell death process because it interferes with protein synthesis and caused internal cellular damage, subsequently causing cell rupturing 24 , which then lead to the release of intracellular components of the cell into the medium. Figure 2 Effect of different concentrations of tested drugs on selected cell physiological function indices to determine cell leakage and ATP synthase loss; ( A ) intracellular protein leakage; ( B ) DNA leakage; ( C ) ATP synthase loss; ( D ) potassium ion leakage.…”
Acinetobacter baumannii is an infectious agent of global proportion and concern, partly due to its proficiency in development of antibiotic resistance phenotypes and biofilm formation. Dithiocarbamates (DTC) have been identified as possible alternatives to the current antimicrobials. We report here the evaluation of several DTC-metal complexes against A. baumannii planktonic cells and biofilms. Among the DTC-metal complexes and DTCs tested, ZnL1 (N-methyl-1-phenyldithiocarbamato-S,S′ Zn(II)), originally designed as an antitumor agent, is effective against biofilm forming A. baumannii. A MIC value of 12.5 µM, comparable to that of Gentamicin (5 µM) was measured for planktonic cells in tryptic soy broth. Spectroscopy, microscopy and biochemical analyses reveal cell membrane degradation and leakage after treatment with ZnL1. Bioelectrochemical analyses show that ZnL1 reduces biofilm formation and decreases extracellular respiration of pre-formed biofilms, as corroborated by microscopic analyses. Due to the affinity of Zn to cells and the metal chelating nature of L1 ligand, we hypothesize ZnL1 could alter metalloprotein functions in the membranes of A. baumannii cells, leading to altered redox balance. Results indicate that the DTC-Zn metal complex is an effective antimicrobial agent against early A. baumannii biofilms under laboratory conditions.
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