Emergence of VIM-1 metallo-β-lactamase-producing Escherichia coli in a neonatal intensive care unit

Epidemiological Study of Carbapenem-resistant Klebsiella Pneumoniae

Background

This research is aimed to study the resistance and molecular epidemiological characteristics of carbapenem-resistant Klebsiella pneumoniae (CRKP).

Methodology

38 isolated CRKP strains were collected from clinical specimens.

Results

The resistance rates were more than 70.0%. Ampicillin had the highest rates among them (100.0%). 34 strains (89.5%) among the 38 CRKP strains carried bla_KPC-2 gene, and 3 strains (7.9%) carried bla_IMP-4 gene. 36 strains (94.7%) among the 38 CRKP strains carried bla_SHV gene, 29 strains (76.3%) carried bla_TEM gene, and 26 strains (68.4%) carried bla_CT-M gene. 7 strains (18.4%) among the 38 CRKP strains carried bla_DHA-1 gene. 15 strains (39.5%) in 38 CRKP strains lost two fenestra proteins, ompK35 and ompK36, and the rest 23 strains carried ompK36 genes. 38 CRKP strains were divided into five kinds of ST types, with ST11 type as the most (86.8%, 33/38). The rest of the ST types included 2 strains of ST23 (5.3%, 2/38), one strain of ST15, ST1373 and ST1415 (2.6%, 1/38).

Conclusions

CRKP resistance is severe, and the mechanism of drug resistance has become increasingly complex. Various ST types and resistance genes are related to CRKP. The clinical prevention and control work is imminent.

Nosocomial outbreak of KPC-2- and NDM-1-producing Klebsiella pneumoniae in a neonatal ward: a retrospective study

Background

The spread of resistance to carbapenems among Enterobacteriaceae has become a major public health problem in recent years. In this study, we describe an outbreak of Klebsiella pneumoniae in the neonatal ward. First, we aimed to study the drug resistance, genetic relatedness, and transmission mechanism of carbapenem-resistant K. pneumoniae; second, we implemented infection control measures to contain the outbreak.

Methods

We investigated 27 non-repetitive strains isolated from neonates and five strains cultured from around the neonatal ward. Polymerase chain reaction (PCR), the agar dilution method, and multilocus sequence typing (MLST) were used to analyze the resistance gene(s), antimicrobial susceptibility, and homology, respectively. Health-care personnel education, hand hygiene, outer gown changing, and infected patient isolation were strictly enforced.

Results

Our antimicrobial susceptibility results show that all strains were multidrug-resistant. MLST and PCR results revealed that, in this study, all of the KPC-2-producing strains are Sequence Type (ST) 11 (ST11) (n = 22) and all of the NDM-1-producing strains are ST20 (n = 4) or ST888 (n = 1). The environmental strains were identified as KPC-2-positive K. pneumoniae ST11 (n = 3) and NDM-1-positive K. pneumoniae ST20 (n = 2). The percentages of isolates with the extended-spectrum-β-lactamases CTX-M-15, blaCTX-M-14, blaTEM-1 were 9.4, 84.3, and 68.8 %, respectively. AmpC β-lactamase genes were not detected in our isolates.

Conclusions

KPC-2-positive K. pneumoniae ST11 and NDM-1-positive K. pneumoniae ST20 were associated with this outbreak. The identification of these isolates in samples from radiant warmers and nurses suggests that hospital cross-transmission played a role in this outbreak. Active infection control measures were effective for controlling this multidrug-resistant K. pneumoniae outbreak.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-016-1870-y) contains supplementary material, which is available to authorized users.

SslE elicits functional antibodies that impair in vitro mucinase activity and in vivo colonization by both intestinal and extraintestinal Escherichia coli strains

SslE, the Secreted and surface-associated lipoprotein from Escherichia coli, has recently been associated to the M60-like extracellular zinc-metalloprotease sub-family which is implicated in glycan recognition and processing. SslE can be divided into two main variants and we recently proposed it as a potential vaccine candidate. By applying a number of in vitro bioassays and comparing wild type, knockout mutant and complemented strains, we have now demonstrated that SslE specifically contributes to degradation of mucin substrates, typically present in the intestine and bladder. Mutation of the zinc metallopeptidase motif of SslE dramatically impaired E. coli mucinase activity, confirming the specificity of the phenotype observed. Moreover, antibodies raised against variant I SslE, cloned from strain IHE3034 (SslE_IHE3034), are able to inhibit translocation of E. coli strains expressing different variants through a mucin-based matrix, suggesting that SslE induces cross-reactive functional antibodies that affect the metallopeptidase activity. To test this hypothesis, we used well-established animal models and demonstrated that immunization with SslE_IHE3034 significantly reduced gut, kidney and spleen colonization by strains producing variant II SslE and belonging to different pathotypes. Taken together, these data strongly support the importance of SslE in E. coli colonization of mucosal surfaces and reinforce the use of this antigen as a component of a broadly protective vaccine against pathogenic E. coli species.

Escherichia coli are the predominant facultative anaerobe of the human colonic flora. Although intestinal and extraintestinal pathogenic E. coli are phylogenetically and epidemiologically distinct, we recently proposed a number of protective antigens conserved in most E. coli pathotypes. In this study, we have elucidated the function of the most promising of these antigens, SslE, which is characterized by the presence of a M60-like domain representative of a new extracellular zinc-metalloprotease sub-family. In particular, in vitro analysis of the ability of an sslE knockout mutant strain to transverse an agar-based mucin matrix revealed that SslE is essential to E. coli mucinase activity. Evidence showing that SslE induces functional antibodies, preventing both in vitro mucin degradation but also in vivo gut, kidney and spleen colonization, further support the hypothesis that SslE may facilitate E. coli colonization by favoring the penetration of the sterile inner mucus layer leading to interaction with host cells. Finally, the ability of SslE to also induce protective immunity against sepsis, linked to its presence among different pathotypes, supports the use of such an antigen as a broadly protective E. coli vaccine candidate.

Epidemiology and prevention of carbapenem-resistant Enterobacteriaceae in the United States

Carbapenem-resistant Enterobacteriaceae (CRE) are multidrug-resistant organisms with few treatment options that cause infections associated with substantial morbidity and mortality. CRE outbreaks have been increasingly reported worldwide and are mainly due to the emergence and spread of strains that produce carbapenemases. In the United States, transmission of CRE is primarily driven by the spread of organisms carrying the Klebsiella pneumoniae carbapenemase enzyme, but other carbapenemase enzymes, such as the New-Delhi metallo-β-lactamase, have also emerged. Currently recommended control strategies for healthcare facilities include the detection of patients infected or colonized with CRE and implementation of measures to prevent further spread. In addition to efforts in individual facilities, effective CRE control requires coordination across all healthcare facilities in a region. This review describes the current epidemiology and surveillance of CRE in the United States and the recommended approach to prevention.