High diversity of extended-spectrum beta-lactamase-producing bacteria in an urban river sediment habitat.

Antibiotic-resistant bacteria (ARB) have been surveyed widely in water bodies, but few studies have determined the diversity of ARB in sediment, which is the most taxon-abundant habitat in aquatic environments. We isolated 56 extended-spectrum beta-lactamase (ESBL)-producing bacteria from a single sediment sample taken from an urban river in China. All strains were confirmed for ESBL-producing capability by both the clavulanic acid combination disc method and MIC determination. Of the isolated strains, 39 were classified as Enterobacteriaceae (consisting of the genera Escherichia, Klebsiella, Serratia, and Aeromonas) by 16S rRNA gene sequencing and biochemical analysis. The present study identifies, for the first time, ESBL-producing strains from the families Brucellaceae and Moraxellaceae. The bla(CTX-M) gene was the most dominant of the ESBL genes (45 strains), while the bla(TEM) gene was the second-most dominant (22 strains). A total of five types of bla(CTX-M) fragments were identified, with both known and novel sequences. A library of bla(CTX-M) cloned from the sediment DNA showed an even higher diversity of bla(CTX-M) sequences. The discovery of highly diverse ESBL-producing bacteria and ESBL genes, particularly bla(CTX), in urban river sediment raises alarms for potential dissemination of ARB in communities through river environments.

[Analysis of distribution, drug resistance and risk factors of pathogens isolated from septicemic patients].

OBJECTIVE: To investigate distribution, drug resistance and risk factors of pathogens isolated from septicemic patients in a hospital in the past 6 years. METHODS: Most of the bacterial isolates were identified with BD Phoenix, and a few isolates were identified manually and with K-B method. Candida isolates were identified with color display plates and K-B method. WHONET5.4 software was used for analysis. RESULTS: The common bacteria isolated form the blood included E. coli, P. aeruginosa, K. pneumoniae, and S. aureu. The gram-negative bacillus from the blood exhibited relatively low resistance to such antibiotics as cefoperazone/sulbactam, imipenem, amikacin, piperacillin/tazobactam, and ceftazidime, and the incidences of E.coli and K. pneumoniae isolates producing extended spectrum beta-lactamase (ESBLs) ranged between 33.3% and 34.9% and between 32.9% and 36.0%, respectively. The gram-positive coccus from blood showed a sensitivity rate of 100.0% to vancomycin and low resistant rates to amikacin and chloramphenicol; the methicillin-resistant rates of S. aureu and coagulase-negative staphylococcus were 26.9%-35.5% and 72.7%-74.3%, respectively. The risk factors of septicemia included hospital stay for over 5 days, venous catheterization, surgeries, puncture, oxygen therapy, urine tract catheterization, and chemotherapy. CONCLUSION: Blood culture can be of importance in patients with septicemia, and the use of antibiotics should be carefully weighed according to the results of bacterial culture and sensitivity tests of the pathogens isolated from the blood.

[Distribution and drug resistance spectrum analysis of 2478 clinical bacterial and Candida isolates].

OBJECTIVE: To investigate the distribution and drug resistance spectrum of clinical bacterial and Candida isolates. METHODS: Most of the bacterial isolates were identified using automated BD Phoenix, and a few with K-B method carried out manually. Candida isolates were identified by color-display plate and K-B method. RESULTS: The most common isolates in the 2478 strains were P. aeruginosa (15.6%), E. coli (11.5%), C. albicans (9.6%), K. pneumoniae (9.3%), S. aureu (8.2%), and S. epidermidis (7.5%). In gram-negative isolates, the antibiotics with the lowest resistance rate were meraopenem (14.4%), cefoperazone/Sulbactam (14.8%), Imipenem (21.9%), piperacillin/tazobactam (27.4%), ceftazidime (30.0%), amikacin (31.1%), and cefepime (33.1%). The detection rate of E.coli and K. pneumoniae isolates producing extended spectrum beta-lactamase (ESBLs) were 47.4% and 37.3% respectively. In gram-positive isolates, the antibiotics with the lowest resistance rate were vancomycin (0.9%), teicoplanin (1.1%), nitrofurantoin (6.9%), amikacin (20.1%), chloramphenicol (30.7%), and cefoperazone/sulbactam (31.5%). The methecillin-resistant rates of S. aureu , S. epidermidis, and S. haemolyticus were 57.1%, 65.0%, and 66.0%. For Candida isolates, the most sensitive antibiotics were amphotericin B (0.3%), nystain (0.3%), itraconazole (5.6%), fluconazole (9.4%), and fluorocytosine (9.4%). CONCLUSION: The results suggest high rate of ESBL production and oxacillin resistance of the bacteria isolated in the hospital. More rational use of antimicrobial agents is crucial for reducing the drug-resistance of the bacteria, and effective measures must be taken to reduce dissemination of multidrug-resistant bacteria.

[Analysis of drug resistance spectrum and its mechanism in 1017 clinical bacterial isolates].

OBJECTIVE: To investigate the drug susceptibility of the clinical bacterial isolates to provide evidence for more adequate use of antibiotics. METHODS: Altogether 1017 clinical bacterial isolates were identified by BD Phoenix and tested for resistance against antimicrobial agents by K-B method. WHONET5 was applied for the analysis. RESULTS: The most frequent bacteria detected included P. aeruginosa (19.37%), coagulase-negative Staphylococci (CNS, 17.70%), E. coli (13.27%), S. aureu (SA, 12.09%), E. faecalis (11.8%), and K. pneumoniae (7.57%). In gram-negative isolates, the susceptibility rate of imipenem was 81.5%, and that of ceftazidime was above 70%. The incidences of E.coli and K. pneumoniae isolates producing extended spectrum beta-lactamase (ESBLs) were 34.8% and 45.5% respectively. In gram-positive isolates, the susceptibility rates of vancomycin and Teicoplanin were 98.8% and 100.0% respectively, and those of furazolidone, imipenem, amikacin, piperacillin/ tazobactam were above 70%. The oxacillin resistant rates of CNS and SA were 78.2% and 46.8%. CONCLUSION: The 1017 clinical bacterial isolates are characterized by high ratio of ESBL production and oxacillin resistance, suggesting the importance of adequate use of antimicrobial agents and effective control measures for reducing the drug resistance and preventing the spread of multi drug- resistant bacteria.

[Investigation of the bacteria in the seawater of Xisha in the South China Sea and their antibiotic sensitivity profile].

OBJECTIVE: To investigate the distribution and antibiotic sensitivity of the bacteria in the seawater of Xisha in the South China Sea. METHODS: The samples of the seawater in Xisha were collected for bacterial counting, identification and antibiotic sensitivity tests. RESULT: Of the 84 bacterial strains isolated from the 80 seawater samples, 38 (45.24%) belonged to Vibrio alginolyticus, 11 (13.10%) to Sphingomonas, 9 (10.72%) to Comamonas terrigena, 7 (8.33%) to Werepseudomonas, 6 (7.14%) to Moraxella, 5 (5.95%) to Cedeceadavisae, and 8 to other bacteria including 2 Aeromona, 2 Acinetobacter, 1 Pantoea agglomerans, 1 Kingella kingae, 1 Shewanella putrefaciens and 1 Suttonella indologenes. Tests of the antibiotic sensitivity showed that all the bacteria were high sensitive to 16 kinds of the antibiotics with the exception of Vibrio alginolyticus, Sphingomonas and comamonas terrigena that were less sensitive to aztreonam or piperacillin and Sphingomonas to cefotaxime or cefepime. CONCLUSION: The investigation will be of great significance for early-stage prevention and cure of bacterial infection acquired from the seawater.

[Survey on drug resistance to ciprofloxacin in common pathogenic bacteria].

OBJECTIVE: To obtain primary knowledge of drug resistance to ciprofloxacin in the common pathogenic bacteria in this hospital thereby to bring the situation under control. METHODS: A total of 3 800 strains of pathogenic bacteria were isolated from in-patients from 1997 to 2000, and drug resistance of these strains to ciprofloxacin was examined. RESULTS: During the past 4 years, Staphylococcus aureus, Staphylococcus epidermidis and Enterococcus faecalis were found to be highly resistant to ciprofloxacin with the rates still on the rise from 50%, 25.6% and 40.3% in 1997 to 62.2%, 53.4% and 63.6% respectively in 2000. Over 40% of Escherichia coli, Klebsiella pneumoniae and Enterobacter were resistant to ciprofloxacin and the percentages for Pseudomonas aeruginosa and Acinetobacter reached 31.1% to 34.0% in 2000. Among the 189 strains of the pathogenic bacteria isolated from patients with sustained infection in our hospital in 2000, over 70% of Staphylococcus aureus, Staphylococcus epidermidis and Enterococcus faecalis were identified as having resistance to ciprofloxacin. CONCLUSION: The percentages of common pathogenic bacteria that are resistant to ciprofloxacin have been considerably high and tend to increase further. Ciprofloxacin abuse needs to be given appropriate attention.