SUMMARY:We investigated the molecular epidemiologic characteristics and virulence of hypermucoviscosity-positive Klebsiella pneumoniae in mainland China. We detected 16 hypermucoviscositypositive strains in 65 total clinical isolates (24.62z). We found that 68.75z (11/16) of the positive strains had K2 genotype and carried the rmpA and iucA genes. Multilocus sequence typing revealed 5 sequence types (STs):, whereas the remaining 4 isolates were defined as other STs. The order of the median lethal dose values for the ST types was ST23 (2.19 × 10 3 CFU/mouse) ＜ ST86 (1.70 × 10 4 CFU/mouse) ＜ ST65 (5.05 × 10 7 CFU/mouse) ＜ the other STs (1.90 × 10 8 CFU/mouse). In conclusion, the K2 with ST65 carrying rmpA and iucA was the most predominant among the hypermucoviscosity-positive K. pneumoniae strains obtained from communityacquired infection cases in Harbin, North China. Sequence types are a valuable tool to predict the risk of K. pneumoniae infection.

Resistance to β-lactam antibiotics through β-lactamase production by Enterobacteriaceae continues to burden the health-care sector worldwide. Traditional methods for detection of β-lactamases are time-consuming and labor-intensive and newer methods with varying capabilities continue to be developed. The objective of this study was to develop a multiplex PCR (M-PCR) system for the detection of bla SHV , bla TEM , bla CTX-M-1 , bla CTX-M-9 and bla OXA-1 group genes and to apply it in clinical Klebsiella pneumoniae and Escherichia coli strains. To do this, we used group-specific PCR primers in singleplex reactions followed by optimization into multiplex reactions. Specificity and sensitivity of the M-PCR were then evaluated using 58 reference strains before its application to detect bla group genes in 203 clinical Enterobacteriaceae strains. PCR amplicons were sequenced to determine the β-lactamase subtypes. The M-PCR system exhibited 100% specificity and sensitivity. In all, 83.7% of K. pneumoniae and 89.8% of E. coli clinical strains harbored bla group genes with 46.9%, 40.1%, 15.0%, 21.1% and 6.1% of K. pneumoniae having bla SHV , bla TEM , bla CTX-M-1 , bla CTX-M-9 and bla OXA-1 group genes, respectively, whereas 12.2%, 77.6%, 22.4%, 36.7% and 8.2% of E. coli had bla SHV , bla TEM , bla CTX-M-1 , bla CTX-M-9 and bla OXA-1 group genes, respectively. Bla SHV-1 , bla SHV-11 , bla SHV-27 , bla SHV-33 , bla SHV-144 , bla TEM-1 , bla TEM-135 , bla OXA-1 , bla CTX-M-3 , bla CTX-M-9 , bla CTX-M-14 , bla CTX-M-15 , bla CTX-M-27 , bla CTX-M-55 , bla CTX-M-65 and bla CTX-M-104 were detected. In conclusion, the M-PCR system was efficient and versatile with an advantage of simultaneously detecting all the targeted bla group genes. Hence, it is a potential candidate for developing M-PCR kits for the screening of these genes for clinical or epidemiological purposes.

The objective of this study was to compare quinolone resistance and gyrA mutations in clinical isolates of Klebsiella pneumoniae and Escherichia coli from Chinese adults who used quinolone in the preceding month and children without any known history of quinolone administration. The antimicrobial susceptibilities of 61 isolates from children and 79 isolates from adults were determined. The mutations in the quinolone resistance-determining regions in gyrA gene were detected by PCR and DNA sequencing. Fluoroquinolone resistance and types of gyrA mutations in isolates from children and adults were compared and statistically analyzed. No significant differences were detected in the resistance rates of ciprofloxacin and levofloxacin between children and adults among isolates of the two species (all P > 0.05). The double mutation Ser83→Leu + Asp87→Asn in the ciprofloxacin-resistant isolates occurred in 73.7% isolates from the children and 67.9% from the adults, respectively (P = 0.5444). Children with no known history of quinolone administration were found to carry fluoroquinolone-resistant Enterobacteriaceae isolates. The occurrence of ciprofloxacin resistance and the major types of gyrA mutations in the isolates from the children were similar to those from adults. The results indicate that precautions should be taken on environmental issues resulting from widespread transmission of quinolone resistance.