OBJECTIVETo investigate the antimicrobial resistance of clinical isolates of Stenotrophomonas matophilia (SMA) and the mechanisms of their drug resistance.

METHODSDisc diffusion method (NCCLS) was used to detect the resistant patterns of 88 initial SMA isolates resistant to 12 antibiotics isolated from a local hospital in the past 4 years. PCR was used to detect the 7 aminoglycosides modifying enzymes genes (AME) against amikacin and gentamicin. Metal-beta-lactamases (MBLs) were screened by synergic method, and extended-spectrum beta-lactamases (ESBLs) were detected by double-disk synergy test.

RESULTSThe resistance rates of the SMA isolates were 0%-9.7% to minocycline, 12.5%-22.6% to ticarcillin-clavulanic acid, 12.5%-28.6% to levofloxacin, 18.8%-33.3% to doxycycline, 18.8%-40% to sulfamethoxazole compound, 50%-65.7% to ciprofloxacin, 50%-66.7% to cehazindme, 54.8%-66.7% to amikacin, 75%-100% to gentamicin, 81.3%-100% to piperacillin, 87.5%-100% to aztreonam and 93.5%-100% to imipenem. Aac(3)-I and ant(4')-II were not detected in these strains. The positive rates of the other 5 AME genes of aac(3)-II, ant(2'')-I, aac(6')-I, aac(3)-III, aac(3)-IV were 2.3%, 5.7%, 8%, 10%, and 10%, respectively. SMA strains producing ESBLs were found at the rate of 38.6%; 25% of the strains were MBL-producing, and 13.6% produced both ESBLs and MBLs.

CONCLUSIONMost of the SMAs we isolated are multidrug-resistant through various mechanisms. The choice of antibiotics should be made according to the susceptibility results.

Amikacin ; pharmacology ; Drug Resistance, Multiple, Bacterial ; Gentamicins ; pharmacology ; Humans ; Imipenem ; pharmacology ; Microbial Sensitivity Tests ; Stenotrophomonas maltophilia ; drug effects ; isolation & purification

OBJECTIVE: To explore the clinical characteristics of hospitalized patients with hematologic diseases complicated with carbapenem-resistant organisms (CRO) infection and analyze the risk factors of 30-day all-cause mortality. METHODS: The clinical data and laboratory test data of 77 hospitalized patients with hematologic diseases complicated with CRO infection in department of hematology of the Third Hospital of Shanxi Medical University from January 2015 to December 2020 were retrospectively analysed, the risk factors of 30-day all-cause mortality after CRO infection were analyzed by multivariate logistic regression. RESULTS: Among the total of 77 patients with hematologic diseases complicated with CRO infection, 29 died and 48 survived within 30 days of infection, with a case fatality rate of 37.66%. A total of 93 strains of CRO were isolated from these patients, of which Acinetobacter baumannii had the highest detection rate (25.81%, 24/93), followed by Pseudomonas aeruginosa (18.28%, 17/93). The lung was the most common site of CRO infection. The detected pathogens were highly resistant to carbapenems, and 64.52% (60/93) of the pathogens were resistant to imipenem with minimum inhibitory concentration (MIC)≥16 μg/ml. The results of the univariate analysis showed that albumin concentration <25 g/L (P =0.048), serum creatinine concentration≥120 μmol/L (P =0.023), age-adjusted Charlson comorbidity index (ACCI) (P =0.037) and primary treatments (supportive treatment, immunosuppressive therapy, chemotherapy, HSCT) (P =0.048) were significantly associated with 30-day all-cause mortality after infection. The results of multivariate logistic regression analysis showed that when CRO infection confirmed, albumin concentration <25 g/L (P =0.014, OR=6.171), serum creatinine concentration≥120 μmol/L (P =0.009, OR=10.867) were independent risk factors for 30-day mortality of patients with hematologic diseases complicated with CRO infection. CONCLUSION The mortality rate of CRO-infected patients with hematologic diseases is high. The detected pathogenic bacteria are highly resistant to imipenem. The albumin concentration <25 g/L and the serum creatinine concentration≥ 120 μmol/L at diagnosis of CRO infection were independent risk factors for 30-day mortality of the patients with hematologic diseases.
Humans ; Carbapenems/pharmacology* ; Retrospective Studies ; Creatinine ; Hematologic Diseases ; Risk Factors ; Imipenem ; Albumins

Anti-Bacterial Agents ; pharmacology ; Drug Resistance, Bacterial ; Humans ; Imipenem ; pharmacology ; Infant ; Klebsiella pneumoniae ; drug effects ; isolation & purification ; Ventilation ; methods

The 5th year KONSAR surveillance in 2001 was based on routine test data at 30 participating hospitals. It was of particular interest to find a trend in the resistances of enterococci to vancomycin, of Enterobacteriaceae to the 3rd generation cephalosporin and fluoroquinolone, and of Pseudomonas aeruginosa and acinetobacters to carbapenem. Resistance rates of Gram-positive cocci were: 70% of Staphylococcus aureus to oxacillin; 88% and 16% of Enterococcus faecium to ampicillin and vancomycin, respectively. Seventy-two percent of pneumococci were nonsusceptible to penicillin. The resistance rates of Enterobacteriaceae were: Escherichia coli, 28% to fluoroquinolone; Klebsiella pneumoniae, 27% to ceftazidime, and 20% to cefoxitin; and Enterobacter cloacae, > or =40% to cefotaxime and ceftazidime. The resistance rates of P. aeruginosa were 21% to ceftazidime, 17% to imipenem, and those of the acinetobacters were > or =61% to ceftazidime, aminoglycosides, fluoroquinolone and cotrimoxazole. Thirty-five percent of non-typhoidal salmonellae were ampicillin resistant, and 66% of Haemophilus influenzae were -lactamase producers. Notable changes over the 1997-2001 period were: increases in vancomycin-resistant E. faecium, and amikacin- and fluoroquinolone-resistant acinetobacters. With the increasing prevalence of resistant bacteria, nationwide surveillance has become more important for optimal patient management, for the control of nosocomial infection, and for the conservation of the newer antimicrobial agents.
Anti-Bacterial Agents/*pharmacology ; Cephalosporins/pharmacology ; *Drug Resistance, Microbial ; Enterococcus faecium/metabolism ; Human ; Imipenem/pharmacology ; Klebsiella pneumoniae/metabolism ; Korea ; Pseudomonas aeruginosa/metabolism ; Time Factors ; Vancomycin/*pharmacology

Antimicrobial resistance surveillance is necessary to determine the size of the problem and to guide empirical selection of antimicrobial agents for treating infected patients. The aim of this study was to analyze the results of susceptibility tests performed by hospitals participating in the Korean Nationwide Surveillance of Antimicrobial Resistance (KONSAR) program. The rates of oxacillin-resistant staphylococci, penicillin-nonsusceptible pneumococci, and ampicillin-resistant E. faecium were over 70%. Ampicillin-resistant H. influenzae increased to 68%. Expanded-spectrum cephalosporin-resistant K. pneumoniae, fluoroquinolone-resistant E. coli, and imipenem-resistant P. aeruginosa remained at 16% through 27%, depending on the species. The proportions of vancomycin-resistant E. faecium and imipenem-resistant P. aeruginosa were 18 - 24% and 19-21%, respectively, indicating the seriousness of antimicrobial resistance. In conclusion, the increasing prevalence of resistant bacteria indicates that more concerted effort is required to conserve the usefulness of precious new antimicrobial agents.
Anti-Bacterial Agents/*pharmacology ; Cephalosporins/*pharmacology ; *Drug Resistance, Microbial ; Enterococcus/*drug effects ; Gram-Negative Bacteria/*drug effects ; Human ; Imipenem/*pharmacology ; Korea ; *Vancomycin Resistance

Acinetobacter Infections ; microbiology ; Acinetobacter baumannii ; drug effects ; isolation & purification ; Anthracosis ; microbiology ; Anti-Bacterial Agents ; pharmacology ; Drug Resistance, Bacterial ; Fosfomycin ; pharmacology ; Humans ; Imipenem ; pharmacology ; Pneumonia, Bacterial ; microbiology

OBJECTIVETo investigate the resistant effect of houttuyfonate sodium (SH) combined with imipenem (IMP) against Pseudomonas aeruginosa (Pa) biofilms.

METHODThe two-fold dilution method was used to examine the minimum inhibitory concentration (MIC) of the tested drug. The crystal violet staining was applied to detect the effect of the combination of 1/2MIC, 1MIC, 2MIC of SH, single IMP, 1/2MIC of SH and IMP of various concentrations on the clearance rate of adherent bacteria, growth of biofilms and alginate production. Fluorescein diacetate (FDA)-propidium iodide (PI) doubling staining assay was employed to observe the bacterial viability and morphological changes after membrane dispersion of each drug group.

RESULTSodium houttuyfonate could enhance the effect of IMP against pseudomonas aeruginosa biofilms. Particularly, the combination group with the concentration of 2MIC showed the highest effect, with P < 0.001 compared with the negative control group. The above results were proved by the bacterial viability and biofilm morphology under fluorescence microscope.

CONCLUSIONAfter being combined with imipenem, sodium houttuyfonate shows a higher effect against biofilms. It is expected that the combination of the two drugs could improve the clinical efficacy of associated infections.

Alkanes ; pharmacology ; Biofilms ; drug effects ; growth & development ; Drug Synergism ; Imipenem ; pharmacology ; Microbial Sensitivity Tests ; Microbial Viability ; drug effects ; Pseudomonas aeruginosa ; drug effects ; physiology ; Sulfites ; pharmacology

PURPOSE: Combination antibiotic treatment is preferred in nosocomial infections caused by Pseudomonas aeruginosa (P. aeruginosa). In vitro synergism tests were used to choose the combinations which might be used in clinic. The aim of this study was to investigate the synergistic efficacy of synergistic antibiotic combinations in multidrug resistant P. aeruginosa strains. MATERIALS AND METHODS: Synergistic efficacies of ceftazidime-tobramycin, piperacillin/tazobactam-tobramycin, imipenem-tobramycin, imipenem-isepamycin, imipenem-ciprofloxacin and ciprofloxacin-tobramycin combinations were investigated by checkerboard technique in 12 multiple-resistant and 13 susceptible P. aeruginosa strains. RESULTS: The ratios of synergy were observed in ceftazidime-tobramycin and piperacillin/tazobactam-tobramycin combinations as 67%, and 50%, respectively, in resistant strains, whereas synergy was not detected in other combinations. The ratios of synergy were observed in ceftazidime-tobramycin, piperacillin/tazobactam-tobramycin, imipenem-tobramycin, imipenem-ciprofloxacin and imipenem-isepamycin combinations as 31%, 46%, 15%, 8%, 8%, and respectively, in susceptible strains, whereas synergy was not detected in ciprofloxacin-tobramycin combination. Antagonism was not observed in any of the combinations. CONCLUSION: Although the synergistic ratios were high in combinations with ceftazidime or piperacillin/tazobactam and tobramycin, the concentrations in these combinations could not usually reach clinically available levels. Thus, the solution of the problems caused by multiple resistant P. aeruginosa should be based on the prevention of the development of resistance and spread of the causative agent between patients.
Anti-Bacterial Agents/*pharmacology ; Ceftazidime/pharmacology ; Ciprofloxacin/pharmacology ; Drug Resistance, Multiple, Bacterial/*drug effects ; Drug Synergism ; Imipenem/pharmacology ; Microbial Sensitivity Tests ; Penicillanic Acid/analogs & derivatives/pharmacology ; Piperacillin/pharmacology ; Pseudomonas aeruginosa/*drug effects ; Tobramycin/pharmacology

OBJECTIVETo analyze the distribution of Enterobacteriaceae isolated from West China Hospital, investigate the antibiotic resistance profile of Enterobacteriaceae with decreased susceptibility to carbapenems and explore the molecular mechanism.

METHODSForty-five Enterobacteriaceae strains resistant or with reduced susceptibility to carbapenems were isolated from patients in West China Hospital. The antimicrobial susceptibility and carbapenemase-producing phenotypes of the bacteria were examined and specific PCR were performed to determine the molecular mechanism.

RESULTSOf the 45 isolates, 17, 21 and 36 were resistant or intermediate strains to imipenem, meropenem and ertapenem, respectively. The majority of these isolates showed resistance to cephalosporins. The modified Hodge test resulted in the highest positivity rate (77.8%), followed by EDTA disc test (57.8%) and PBA disc test (22.2%). BlaTEM, blaSHV and blaCTX-M were detected in 60.0%, 53.3% and 15.6% of these strains with reduced susceptibility. The rate of strains carrying 2 or more genes was 44.4%, and the detection rate of blaIMP was 48.9%. BlaKPC was identified in 4 (8.9%) high-level resistant strains and confirmed to locate on the plasmid.

CONCLUSIONProduction of carbapenemase contributes to reduced susceptibility of carbapenems in Enterobacteriaceae. The presence of blaKPC, MBL and ESBL, and their possible combinations can be the main factor contributing to carbapenem resistance or reduced susceptibility in Enterobacteriaceae. The KPC-2 carbapenemase gene located on the plasmids we found in this study can cause potential horizontal transmission across strains.

Anti-Bacterial Agents ; pharmacology ; Bacterial Proteins ; genetics ; metabolism ; Carbapenems ; pharmacology ; Cephalosporins ; pharmacology ; Enterobacteriaceae ; drug effects ; enzymology ; genetics ; Gene Amplification ; Imipenem ; pharmacology ; Microbial Sensitivity Tests ; Polymerase Chain Reaction ; Thienamycins ; pharmacology ; beta-Lactam Resistance ; beta-Lactamases ; genetics ; metabolism ; beta-Lactams ; pharmacology

BACKGROUNDMycobacterium abscessus (M. abscessus) can cause a variety of human infections, involving the lung, skin and soft tissues, and is generally believed to be acquired from environmental sources. The aim of this study was to investigate the molecular diversity and antibiotic susceptibility of M. abscessus isolates as the basis for strategies to improve control and management of infection.

METHODSSeventy M. abscessus isolates from patients attending the Guangzhou Thoracic Hospital were identified from 2003 to 2005 by biochemical tests, gas chromatography, polymerase chain reaction (PCR)-restriction analysis (PRA) of heat shock protein gene hsp65, and sequencing of the quinolone resistance determining regions (QRDRs) of gyrA. Susceptibilities to six antibiotics were determined by micro-broth dilution. Isolates were genotyped using randomly amplified polymorphic DNA (RAPD) analysis.

RESULTSMost isolates (63/70; 90%) were susceptible to amikacin but rates of susceptibility to other antibiotics varied from moderate, clarithromycin (60%) and imipenem (43%), to low for ciprofloxacin and ofloxacin (3%), and 87% of isolates had intermediate susceptibility to cefoxitin. RAPD analysis showed that the 70 clinical isolates displayed 69 unique RAPD patterns.

CONCLUSIONSThe high genetic diversity of isolates suggests that they are not transmitted from person to person but, presumably, are acquired independently from environmental sources. M. abscessus isolates displayed variable levels of susceptibility to all antibiotics tested, other than amikacin, indicating a need for routine susceptibility testing to guide treatment.

Amikacin ; pharmacology ; Anti-Bacterial Agents ; pharmacology ; Cefoxitin ; pharmacology ; China ; Chromatography, Gas ; Ciprofloxacin ; pharmacology ; Clarithromycin ; pharmacology ; Imipenem ; pharmacology ; Microbial Sensitivity Tests ; Mycobacterium ; drug effects ; genetics ; Polymerase Chain Reaction ; Random Amplified Polymorphic DNA Technique