NDM-1 (New Delhi metallo beta lactamase-1) producing Gram-negative bacilli: Emergence & clinical implications.

Backgound & objectives: resistance to carbapenems in Gram-negative bacteria conferred by NDM-1 is a global health problem. We investigated the occurrence of NDM-1 in clinical isolates of gram-negative bacilli in a tertiary care hospital in Kashmir valley, India. Methods: Gram-negative bacilli from different clinical isolates were included in the study. Antimicrobial susceptibility was performed by Kirby Bauer disk diffusion method and interpreted using Clinical Laboratory Standards Institute (CLSI) guidelines. Isolates resistant to carbapenems were subjected to different phenotypic test such as modified hodge test (MHT), boronic acid and oxacillin based MHT (bA-MHT and OXA-MHT), combined disk test and minimum inhibitory concentration (MIC) with imipenem and imipenem -EDTA for determination of class B metallo enzymes. Presence of blaNDM-1 gene was established by PCR and confirmed by sequencing. Results: Of the total 1625 gram-negative isolates received, 100 were resistant to imipenem. Of the 100 isolates, 55 (55%) were positive by modified Hodge test indicating carbapenemase production. Of the 100 isolates tested by MHT, BA-MHT and OXA-MHT, 29 (29%) isolates belonged to Class A and 15 (15%) to Class B, while 56 (56%) isolates were negative. Of the 15 class B metallo beta lactamase producers, nine carried the blaNDM-1 gene. NDM-1 was found among escherichia coli (2 isolates), Klebsiella pneumoniae (2 isolates), Citrobacter freundii (3 isolates), Acinetobacter spp (1 isolate), and one isolate of Pseudomonas aeruginosa. Isolates were resistant to all antibiotic tested except polymyxin B and tigecycline. Interpretation & conclusions: Our study showed the presence of clinical isolates expressing NDM-1 in Srinagar, Jammu & Kashmir, India. These isolates harbour plasmid mediated multiple drug resistant determinants and can disseminate easily across several unrelated genera. To halt their spread, early identification of these isolates is mandatory.

Changes in Causative Pathogens of Acute Cholangitis and Their Antimicrobial Susceptibility over a Period of 6 Years / 대한소화기학회지

BACKGROUND/AIMS: We evaluated changes of causative pathogen in acute cholangitis and their antimicrobial susceptibility over six years and differences between community-acquired and hospital-acquired acute cholangitis at our institution. METHODS: Medical records of 1,596 patients with acute cholangitis and biliary drainage between August 2006 and August 2012 were reviewed retrospectively. Cases were divided according to time: period 1 (August 2006-December 2008, n=645, 40.4%), period 2 (January 2009-August 2012, n=951, 59.6%). Cases were divided according to community-acquired cholangitis (n=1,397, 87.5%) and hospital-acquired cholangitis (n=199, 12.5%). Causative pathogens and antimicrobial susceptibility were investigated in each group. RESULTS: Causative pathogen was isolated from bile culture in 1,520 out of 1,596 cases (95.2%). The three most frequently isolated Gram-negative bacteria were extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli (n=485, 30.4%), E. coli (n=237, 13.2%), and Citrobacter freundii (n=110, 6.9%). Between periods 1 and 2, prevalence of ESBL-producing E. coli and Klebsiella pneumoniae did not show significant change (36.7% vs. 32.1%, p=0.073; 6.6% vs. 6.2%, p=0.732). C. freundii showed a significant increase from period 1 to period 2 (1.7% vs. 13.2%, p=0.000). In both time periods, imipenem was the antimicrobial agent showing the highest rate of susceptibility (93.3% vs. 93.9%, p=0.783). Higher prevalence of ESBL-producing E. coli and C. freundii was observed in the hospital-acquired cholangitis group (52.1% vs. 31.2%, p=0.000; 15.9% vs. 7.3%, p=0.001). CONCLUSIONS: The most common causative pathogen of acute cholangitis was ESBL-producing E. coli. Prevalence of C. freundii increased over the time period. Imipenem should be reserved as an alternative for resistant pathogens.

First Detection of VIM-4 Metallo-beta-Lactamase-Producing Citrobacter freundii in China

No abstract available.

Identification of ACT-1 Plasmid-Mediated AmpC beta-Lactamase Producing Citrobacter freundii from a Chinese Patient

No abstract available.

Transferecia de de ß-lactamasas de espectro extendido desde cepas hospitalarias de Klebsiella pneumoniae a otras especies de enterobacterias / Transference of extended-spectrum ß-lactamases from nosocomial strains of Klebsiella pneumoniae to other species of Enterobacteriaceae

Background: Klebsiella pneumoniae is an important pathogenic bacterium, frequently isolated from nosocomial samples, that exhibits wide antimicrobial resistance profiles, including third generation cephalosporins (3GC), aminoglycosides and quinolones. The resistance to 3GC is mainly due to the synthesis of extended spectrum beta lactamases (ESBL), encoded by conjugative plasmids. Aim: To investigate the potential transference of resistance to 3GC from nosocomial strains of K. pneumoniae to other clinical strains of various species of Enterobacteriaceae. Material and methods: The mating experiments were carried out in liquid media and three nosocomial strains of K. pneumoniae were used as donors. These strains were ESBL-producers and resistant to, at least, one of the 3GC assayed. One strain of Citrobacter freundii, Salmonella typhimurium, Serratia marcescens and Escherichia coli, isolated from clinical specimens, were used as recipients. The presence of bla genes was investigated by PCR. Results: The three nosocomial strains of K. pneumoniae were able to transfer the resistance to 3GC and the genes encoding the ESBL to the susceptible recipient strains of enterobacteria. The frequency of transference was as high as 3.2 x 10-2 transconjugants/recipient cell when the strain of Citrobacter freundii was used as recipient. All transconjugants exhibited high level of resistance to the 3GC assayed. Conclusions: Strains of K. pneumoniae isolated from Chilean hospitals are able to disseminate the ESBL genes to clinical strains of others species of Enterobacteriaaceae.