Giuseppe Cornaglia

Clinical epidemiology of the global expansion of Klebsiella pneumoniae carbapenemases.

Klebsiella pneumoniae carbapenemases (KPCs) were originally identified in the USA in 1996. Since then, these versatile β-lactamases have spread internationally among Gram-negative bacteria, especially K pneumoniae, although their precise epidemiology is diverse across countries and regions. The mortality described among patients infected with organisms positive for KPC is high, perhaps as a result of the limited antibiotic options remaining (often colistin, tigecycline, or aminoglycosides). Triple drug combinations using colistin, tigecycline, and imipenem have recently been associated with improved survival among patients with bacteraemia. In this Review, we summarise the epidemiology of KPCs across continents, and discuss issues around detection, present antibiotic options and those in development, treatment outcome and mortality, and infection control. In view of the limitations of present treatments and the paucity of new drugs in the pipeline, infection control must be our primary defence for now.

Metallo-β-lactamases: a last frontier for β-lactams?

Metallo-β-lactamases are resistance determinants of increasing clinical relevance in Gram-negative bacteria. Because of their broad range, potent carbapenemase activity and resistance to inhibitors, these enzymes can confer resistance to almost all β-lactams. Since the 1990s, several metallo-β-lactamases encoded by mobile DNA have emerged in important Gram-negative pathogens (ie, in Enterobacteriaceae, Pseudomonas aeruginosa, and Acinetobacter baumannii). Some of these enzymes (eg, VIM-1 and NDM-1) have been involved in the recent crisis resulting from the international dissemination of carbapenem-resistant Klebsiella pneumoniae and other enterobacteria. Although substantial knowledge about the molecular biology and genetics of metallo-β-lactamases is available, epidemiological data are inconsistent and clinical experience is still lacking; therefore, several unsolved or debatable issues remain about the management of infections caused by producers of metallo-β-lactamase. The spread of metallo-β-lactamases presents a major challenge both for treatment of individual patients and for policies of infection control, exposing the substantial unpreparedness of public health structures in facing up to this emergency.

Acquired carbapenemases in Gram-negative bacterial pathogens: detection and surveillance issues

Acquired carbapenemases are emerging resistance determinants in Gram-negative pathogens, including Enterobacteriaceae, Pseudomonas aeruginosa and other Gram-negative non-fermenters. A consistent number of acquired carbapenemases have been identified during the past few years, belonging to either molecular class B (metallo-beta-lactamases) or molecular classes A and D (serine carbapenemases), and genes encoding these enzymes are associated with mobile genetic elements that allow their rapid dissemination in the clinical setting. Therefore, detection and surveillance of carbapenemase-producing organisms have become matters of major importance for the selection of appropriate therapeutic schemes and the implementation of infection control measures. As carbapenemase production cannot be simply inferred from the resistance profile, criteria must be established for which isolates should be suspected and screened for carbapenemase production, and for which tests (phenotypic and/or genotypic) should be adopted for confirmation of the resistance mechanism. Moreover, strategies should be devised for surveillance of carbapenemase producers in order to enable the implementation of effective surveillance programmes. The above issues are addressed in this article, as a follow-up to an expert meeting on acquired carbapenemases that was recently organized by the ESCMID Study Group for Antibiotic Resistance Surveillance.

Characterization of the Metallo-β-Lactamase Determinant of Acinetobacter baumannii AC-54/97 Reveals the Existence of bla IMP Allelic Variants Carried by Gene Cassettes of Different Phylogeny

ABSTRACT The metallo-β-lactamase determinant of Acinetobacter baumannii AC-54/97, a clinical isolate from Italy that was previously shown to produce an enzyme related to IMP-1, was isolated by means of a PCR methodology which targets amplification of gene cassette arrays inserted into class 1 integrons. Sequencing revealed that this determinant was an allelic variant (namedblaIMP-2) of blaIMPfound in Japanese isolates and that it was divergent from the latter by 12% of its nucleotide sequence, which evidently had been acquired independently. Similar to blaIMP,blaIMP-2 was also carried by an integron-borne gene cassette. However, the 59-base element of theblaIMP-2 cassette was unrelated to those of theblaIMP cassettes found in Japanese isolates, indicating a different phylogeny for the gene cassettes carrying the two allelic variants. Expression of the integron-borneblaIMP-2 gene in Escherichia coliresulted in a significant decrease in susceptibility to a broad array of β-lactams (ampicillin, carbenicillin, cephalothin, cefoxitin, ceftazidime, cefepime, and carbapenems). The IMP-2 enzyme was purified from an Escherichia coli strain carrying the cloned determinant, and kinetic parameters were determined with several β-lactam substrates. Compared to IMP-1, the kinetic parameters of IMP-2 were similar overall with some β-lactam substrates (cefoxitin, ceftazidime, cefepime, and imipenem) but remarkably different with others (ampicillin, carbenicillin, cephaloridine, and meropenem), revealing a functional significance of at least some of the mutations that differentiate the two IMP variants. Present findings suggest that the environmental reservoir of blaIMP alleles could be widespread and raise a question about the global risk of their transfer to clinically relevant species.

Controlling the spread of carbapenemase-producing Gram-negatives: therapeutic approach and infection control

Although the rapid spread of carbapenemase-producing Gram-negatives (CPGNs) is providing the scientific community with a great deal of information about the molecular epidemiology of these enzymes and their genetic background, data on how to treat multidrug-resistant or extended drug-resistant carbapenemase-producing Enterobacteriaceae and how to contain their spread are still surprisingly limited, in spite of the rapidly increasing prevalence of these organisms and of their isolation from patients suffering from life-threatening infections. Limited clinical experience and several in vitro synergy studies seem to support the view that antibiotic combinations should be preferred to monotherapies. But, in light of the data available to date, it is currently impossible to quantify the real advantage of drug combinations in the treatment of these infections. Comprehensive clinical studies of the main therapeutic options, broken down by pathogen, enzyme and clinical syndrome, are definitely lacking and, as carbapenemases keep spreading, are urgently needed. This spread is unveiling the substantial unpreparedness of European public health structures to face this worrisome emergency, although experiences from different countries-chiefly Greece and Israel-have shown that CPGN transmission and cross-infection can cause a substantial threat to the healthcare system. This unpreparedness also affects the treatment of individual patients and infection control policies, with dramatic scarcities of both therapeutic options and infection control measures. Although correct implementation of such measures is presumably cumbersome and expensive, the huge clinical and public health problems related to CPGN transmission, alongside the current scarcity of therapeutic options, seem to fully justify this choice.

A European care bundle for prevention of ventilator-associated pneumonia

BackgroundOne recent approach to facilitating guideline implementation involves the use of care bundles.MethodsThis document presents a care bundle package addressing VAP prevention in an attempt to promote guideline-compliant practices. Uniquely, the development of these care bundles used a formalised methodology to assess the supporting data, based on multi-criteria decision analysis.ResultsThe resulting VAP care bundles for prevention were: non-ventilatory circuit changes unless specifically indicated, alcohol hand hygiene, appropriately educated and trained staff, incorporation of sedation control and weaning protocols into patient care, and oral care with clorhexidine.ConclusionAdoption of these care bundles should rationalise VAP prevention practises and improve outcomes, such as length of stay.

Hospital Outbreak of Carbapenem-Resistant Pseudomonas aeruginosa Producing VIM-1, a Novel Transferable Metallo-β-Lactamase

A total of 8 Pseudomonas aeruginosa isolates was collected from 7 different patients in different wards of the University Hospital of Verona, Italy, from February 1997 to February 1998. The high level of resistance to carbapenems (imipenem minimum inhibitory concentration was always >128 microg/mL) and other broad-spectrum beta-lactams and the rate of imipenem hydrolysis and its inhibition by ethylenediamine-tetra-acetic acid were all suggestive of production of a carbapenem-hydrolyzing metallo-beta-lactamase. A specific DNA probe derived from the recently cloned bla(VIM-1) gene hybridized to all the isolates. A genomic DNA fingerprinting profile revealed clonal relatedness for 7 of 8 isolates. A description of this hospital outbreak is reported, the occurrence of which confirms that proliferation of metallo-beta-lactamase-producing strains multiply resistant to beta-lactams is already a reality outside Japan. These findings emphasize the need for early recognition of similar isolates.

New Delhi metallo-beta-lactamase (NDM-1): towards a new pandemia?

During the past decade the increase of antibiotic resistance in Enterobacteriaceae has become a major concern worldwide. Although beta-lactams have been widely used as the mainstay of treatment for severe infections due to these bacteria, with carbapenems often representing last-resource drugs, carbapenem resistance due to acquired carbapenemases has emerged and spread worldwide since the early 2000s, being even more worrisome for public health because these bacteria are a common source of hospital-acquired infections. Carbapenemases have been now studied in depth, and widely differ from one another, including enzymes from class B (metallo-beta-lactamases, MBLs), class A and class D (serine carbapenemases) [1]. The most prevalent carbapenemase so far in Enterobacteriaceae is the KPC-type class-A carbapenemase, which has been found in Klebsiella pneumonia, especially in the United States, Asia, the United Kingdom, Israel and southern Europe [2]. Interestingly, acquired carbapenemases have been mainly restricted to geographical areas and to specific bacterial species, and outbreaks as well as spread in other countries have been often associated with imported cases from countries where the bacteria are endemic. Population mobility is known to be a main factor in globalization and spreading of antimicrobial drug-resistant organisms [3]. For example, the emergence of KPC-producing Enterobacteriaceae in the United States in 2001 [2] could be later associated with the emergence of travel-related outbreaks in other countries [1,4]. The New Delhi metallo-beta-lactamase (NDM-1) is a novel type of MBL named after the city of origin, which has been recently criticized, following a common practice with transferable MBLs since VIM-1 was named after Verona, Italy [5]. NDM-1 was first reported in 2009 in a Swedish patient of Indian origin, who travelled to New Delhi and acquired a urinary tract infection due to a carbapenem-resistant K. pneumoniae strain resistant to all antibiotics tested except colistin [6]. Faecal samples collected from this patient during his stay at the nursing home yielded an NDM-1 positive E. coli as well [6]. The NDM-1 encoding gene is located on different large plasmids (a 180-kb plasmid for K. pneumoniae and a 140-kb plasmid for E. coli) that are easily transferable to susceptible E. coli J53 at a high frequency [6]. These plasmids also harbour genes conferring resistance to almost all antibiotics, thus making their rapid dissemination in clinically relevant bacteria a serious threat for therapy. Following this first case, sporadic cases of infection due to NDM-1 positive bacteria have been detected, including an E. coli from blood cultures of a patient of Indian origin in the United Kingdom [7], three cases of Enterobacteriaceae isolates (one E. coli, one K. pneumoniae and one E. cloacae) in the United States from patients who received care in India [8], and three cases of Acinetobacter baumannii from New Delhi [9]. In the August issue of the journal The Lancet: Infectious Diseases, a multinational team reported the emergence and spread of 180 cases of patients infected by bacteria carrying the NDM-1, including 37 cases in the United Kingdom and 143 cases in various sites in Pakistan and India, thus suggesting a widespread dissemination [10]. Among these bacteria many different Enterobacteriaceae species were identified, including K. pneumonia, E. coli, E. cloacae, Proteus spp., Citrobacter freundii, K. oxytoca, M. morganii and Providencia spp. Most isolates remained susceptible to colistin and tigecycline, except those Enterobacteriaceae endowed with a natural resistance to these compounds such as M. morganii, Proteus spp. and Providencia spp. Most plasmids detected in these bacteria were easily transferable and capable of wide rearrangement, suggesting a widespread transmission and plasticity among bacterial populations. Interestingly, among the 25 patients detected in the UK, 17 patients had travelled to India or Pakistan within 1 year and 14 had been hospitalized in these countries showing a worldwide dissemination of a new ‘superbug’ from a local source in Asia [10]. Indeed, since August 2010, spreading and dissemination has occurred, with several cases being reported by national and international media from other countries in all continents, including the United States and Canada, Europe (Sweden, the United Kingdom, Austria, Belgium, France, Netherlands and Germany), Japan, Africa,

High-Level Fluoroquinolone-Resistant Clinical Isolates of Escherichia coli Overproduce Multidrug Efflux Protein AcrA

ABSTRACT Immunoblotting with antibody against AcrA, an obligatory component of the AcrAB multidrug efflux system, showed that this protein was overexpressed by ≥170% in 9 of 10 clinical isolates ofEsherichia coli with high-level ciprofloxacin resistance (MICs, ≥32 μg/ml) but not in any of the 15 isolates for which the MIC was ≤1 μg/ml.

Resistance of Streptococcus pyogenes to Erythromycin and Related Antibiotics in Italy

A survey of antimicrobial resistance in Streptococcus pyogenes, performed within the framework of a national surveillance program, has revealed a dramatic increase in resistance of S. pyogenes to erythromycin in most areas of Italy. In virtually all the centers that provided data for 3 consecutive years, the incidence of erythromycin-resistant strains increased twofold to 20-fold from 1993 to 1995 and was greater than 30% in five of the 14 centers participating in the study. The clonality of erythromycin-resistant isolates was studied in 15 strains isolated from different patients at the Institute of Microbiology of Verona University (Verona). The features of the Verona isolates and the substantially different rates of erythromycin and clindamycin resistance observed in most centers suggest that the spread of different resistance genes in multiple clones might be occurring throughout the country.