Virulence Factors and TEM-Type β-Lactamases Produced by Two Isolates of an Epidemic Klebsiella pneumoniae Strain

Abstract

Two Klebsiella pneumoniae isolates of the same strain, identified in Poland, produced either TEM-47 or TEM-68, which differed by the Arg275Leu substitution. They harbored a few virulence factors, including an iron-chelating factor and capsule overproduction, suggesting that these factors were sufficient to enhance their nosocomial potency. TEM-68 and TEM-47 had similar enzymatic activities, but TEM-68 was less susceptible to inhibitors than TEM-47. These results confirm the role of the Arg275Leu substitution in the evolution of TEM enzymes. K lebsiella pneumoniae strains are responsible for communityacquired and nosocomial infections. Different virulence factors have been involved in the infective potency of the community-acquired strains, such as K1 and K2 capsular serotypes, types 3 and 1 fimbriae, capsule synthesis, production of iron-chelating agents, hypermucoviscosity, biofilm formation ability, and the presence of the genomic island encoding the biosynthesis of the colibactin (3,10,11,14,17,18,20,25,27,33,40). However, data concerning the virulence factors expressed by nosocomial strains of K. pneumoniae are scarce. The strains responsible for nosocomial epidemics are usually multiresistant to antibiotics, and most of them produce extended-spectrum ␤-lactamases (ESBLs) (8,26). The largest ESBL family is the TEM family (5). However, another subgroup of enzymes has appeared that combine the substitutions observed in the ESBLs and in the inhibitor-resistant TEM (IRT): its members were designated complex mutant TEMs (CMTs). They have been observed mainly in Escherichia coli and mostly in France (16,29,31,[34][35][36][37]39). The enzyme TEM-68 (CMT-2) was identified by Fiett et al. in an epidemic strain of K. pneumoniae and appeared to have emerged from the ESBL TEM-47 (16). The clinical isolate that produced the ESBL TEM-47 was isolated from eight patients hospitalized in the neonatal ward of the University Hospital of Wrocław, Poland. During this spread, another isolate, which produced TEM-68, was isolated from the respiratory tract of a ninth newborn. All of the isolates were indistinguishable by pulsed-field gel electrophoresis (15). TEM-68 and TEM-47 differed from TEM-1 by the substitutions Gly238Ser, Glu240Lys, and Thr265Met. TEM-68 differed from TEM-47 by the substitution Arg275Leu observed in the IRT TEM-103 (IRT-28) (1,16).In this work, we studied the virulence factors that could have allowed their nosocomial dissemination and characterized the enzymes TEM-47, TEM-68, and TEM-103 to understand the role of the Arg275Leu substitution in TEM evolution.Multilocus sequence type analysis confirmed that all the isolates belonged to the same new sequence type (ST), ST514 (9). The clinical isolates 3144 and 3151, which produced TEM-47 and TEM-68, respectively, were selected for further experiments. They did not belong to the K1 or K2 genotypes (15). They were investigated for the presence of different virulence genes as recommended by Brisse et al. (3), for the presence of the colibactin genomic island (32), a...

Emergence of the third-generation cephalosporin-resistant hypervirulent Klebsiella pneumoniae due to the acquisition of a self-transferable blaDHA-1-carrying plasmid by an ST23 strain

“…To date, third-generation cephalosporins have been the main antibiotics for the treatment for of infections caused by hypervirulent K. pneumoniae [ 29 ]. Recently, the emergence of multidrug-resistant hypervirulent K. pneumoniae strains has been reported in different countries, which include a broad range of sequence types [ 8 , 11 , 30 ]. The ST23 MDR-hvKP strain RJA166 presented here is the first hvKP strain with resistances to the third-generation cephalosporins collected in the ICU of our hospital.…”

Diversity of β-lactam resistance genes in gram-negative rods isolated from a municipal wastewater treatment plant

“…Another variant, bla TEM-30 , was also found in clinical strains of Enterobacteriaceae, with high frequency of isolates in Spain (Martín et al 2010;Ortega et al 2012) and minor identifications in Israel, the UK (NZ_FLMS01000013.1), Sweden (NZ_KE701793.1), Portugal (NG_050260.1), Vietnam (NZ_CZLO01000043.1), the USA, and Poland (Bradford et al 2004;Empel et al 2008;Leavitt et al 2009). Both bla TEM-47 and bla TEM-68 were previously identified mostly in clinical strains of Enterobacteriaceae in Polish hospitals (Gniadkowski et al 1998;Baraniak et al 2005;Robin et al 2012). The bla TEM-68 variant probably evolved from bla TEM-47 , and both are not very frequent in Poland.…”

High-throughput genomic technology in research of virulence and antimicrobial resistance in microorganisms causing nosocomial infections

“…Although several virulence factors are described as being involved in the infective potency of the community-acquired strains, data concerning for virulence determinants expressed by nosocomial strains of Klebsiella species are scarce. However, most clinical isolates possess a well-de ned polysaccharide capsule that appears to be a critical virulence factor [131]. e capsular material forms thick bundles of brillous structures covering the bacterial surface in massive layers, preventing the bacterium from phagocytosis by polymorphonuclear leukocytes [132].…”