Occurrence of False Positive Results for the Detection of Carbapenemases in Carbapenemase-Negative Escherichia coli and Klebsiella pneumoniae Isolates

Adequate detection of the production of carbapenemase in Enterobacteriaceae isolates is crucial for infection control measures and the appropriate choice of antimicrobial therapy. In this study, we investigated the frequency of false positive results for the detection of carbapenemases in carbapenemase-negative Escherichia coli and Klebsiella pneumoniae clinical isolates by the modified Hodge test (MHT). Three hundred and one E. coli and K. pneumoniae clinical isolates were investigated. All produced extended spectrum β-lactamases (ESBLs) but were susceptible to carbapenems. Antimicrobial susceptibility testing was performed by the disk diffusion and agar dilution methods. The MHT was performed using the standard inoculum of test organisms recommended by the CLSI. Genes that encoded ESBLs and carbapenemases were identified by PCR and DNA sequencing. Among the 301 clinical isolates, none of the isolates conformed to the criteria for carbapenemase screening recommended by the CLSI. The susceptibility rates for imipenem, meropenem, and ertapenem all were 100.0%, 100.0%, and 100.0%, respectively. Of the 301 E. coli and K. pneumoniae isolates, none produced carbapenemase. The MHT gave a positive result for 3.3% (10/301) of the isolates. False positive results can occur when the MHT is used to detect carbapenemase in ESBL-producing isolates and clinical laboratories must be aware of this fact

A new species of the leafhopper genus Diomma Motschulsky (Hemiptera, Cidadellidae, Typhlocybinae) from China

In the present paper, a new species is added to the genus Diomma Motschulsky (Hemiptera: Cicadellidae: Typhlocybinae) from Southwest China, D. pincersa sp. n. At the same time, a key can distinguish all Chinese species of the genus is provided

Three new species of the leafhopper genus Tautoneura Anufriev (Hemiptera, Cicadellidae, Typhlocybinae) from China

In the present paper, three new species are added to the genus Tautoneura Anufriev from China, T. baiyunshana sp. n., T. caoi sp. n. and T. yunnanensis sp. n. A key to species recorded from China is provided

False-positive result on MHT.

<p>A, K2821 <i>K. pneumoniae</i> (KPC-2 carbapenemase producer). B, 08-438 <i>E.coli</i>. C, 08-97 <i>K. pneumoniae</i>. D, <i>E. coli</i> ATCC 25922.</p

Antimicrobial activities of various antimicrobial agents against 301 <i>E. coli</i> and <i>K. pneumoniae</i> isolates.

<p>Antimicrobial activities of various antimicrobial agents against 301 <i>E. coli</i> and <i>K. pneumoniae</i> isolates.</p

The characteristics of the 10 false-positive isolates by MHT.

<p>The characteristics of the 10 false-positive isolates by MHT.</p

1. K1933 <i>K. Pneumoniae</i> (Sensitive to cefazolin, no ESBL and carbapenemase producer), 2. 08-97 <i>K. Pneumoniae</i>, 3. 08-1105 <i>K. Pneumoniae</i>, 4. 08-466 <i>K. Pneumoniae</i>, 5. 08-893 <i>K. Pneumoniae</i>, M. Marker.

<p>1. K1933 <i>K. Pneumoniae</i> (Sensitive to cefazolin, no ESBL and carbapenemase producer), 2. 08-97 <i>K. Pneumoniae</i>, 3. 08-1105 <i>K. Pneumoniae</i>, 4. 08-466 <i>K. Pneumoniae</i>, 5. 08-893 <i>K. Pneumoniae</i>, M. Marker.</p

General Oriented Formation of Carbon Nanotubes from Metal–Organic Frameworks

Carbon nanotubes (CNTs) are of great interest for many potential applications because of their extraordinary electronic, mechanical and structural properties. However, issues of chaotic staking, high cost and high energy dissipation in the synthesis of CNTs remain to be resolved. Here we develop a facile, general and high-yield strategy for the oriented formation of CNTs from metal–organic frameworks (MOFs) through a low-temperature (as low as 430 °C) pyrolysis process. The selected MOF crystals act as a single precursor for both nanocatalysts and carbon sources. The key to the formation of CNTs is obtaining small nanocatalysts with high activity during the pyrolysis process. This method is successfully extended to obtain various oriented CNT-assembled architectures by modulating the corresponding MOFs, which further homogeneously incorporate heteroatoms into the CNTs. Specifically, nitrogen-doped CNT-assembled hollow structures exhibit excellent performances in both energy conversion and storage. On the basis of experimental analyses and density functional theory simulations, these superior performances are attributed to synergistic effects between ideal components and multilevel structures. Additionally, the appropriate graphitic N doping and the confined metal nanoparticles in CNTs both increase the densities of states near the Fermi level and reduce the work function, hence efficiently enhancing its oxygen reduction activity. The viable synthetic strategy and proposed mechanism will stimulate the rapid development of CNTs in frontier fields