Alessandra Giordano

Klebsiella pneumoniae ST258 producing KPC-3 identified in Italy carries novel plasmids and OmpK36/OmpK35 porin variants

ABSTRACT A carbapenemase-resistant Klebsiella pneumoniae strain, clone ST258 producing KPC-3, was fully characterized. The entire plasmid content was investigated, thereby identifying plasmids of the IncFIIk (two of them similar to pKPQIL and pKPN3, respectively), IncX, and ColE types, carrying a formidable set of resistance genes against toxic compounds, metals, and antimicrobial drugs and a novel iron(III) uptake system.

Molecular Epidemiology of Escherichia coli Producing Extended-Spectrum β-Lactamases Isolated in Rome, Italy

ABSTRACT Escherichia coli strains producing extended-spectrum β-lactamases (ESBLs) are a major problem in many different hospitals worldwide, causing outbreaks as well as sporadic infections. The prevalence of Escherichia coli ESBL producers was analyzed in a surveillance study performed on the population attending the Policlinico Umberto I, the largest university hospital in Rome, Italy. We also investigated genotypes, pathogenicity islands, and plasmids in the ESBL-positive E. coli isolates as further markers that are useful in describing the epidemiology of the infections. In this survey, 163 nonreplicate isolates of Escherichia coli were isolated from patients from 86 different wards, and 28 were confirmed as ESBL producers. A high prevalence (26/28) of CTX-M-15 producers was observed within the bacterial population circulating in this hospital, and the dissemination of this genetic trait was associated with the spread of related strains; however, these do not have the characteristics of a single epidemic clone spreading. The dissemination was also linked to horizontal transfer among the prevalent E. coli genotypes of multireplicon plasmids showing FIA, FIB, and FII replicons in various combinations, which are well adapted to the E. coli species. The analysis of related bacteria suggests a probable interpatient transmission occurring in several wards, causing small outbreaks.

An Ertapenem-Resistant Extended-Spectrum-β-Lactamase-Producing Klebsiella pneumoniae Clone Carries a Novel OmpK36 Porin Variant

ABSTRACT Carbapenem-resistant Klebsiella pneumoniae caused an outbreak in a hospital in Rome, Italy. The clinical isolates were tested by antimicrobial susceptibility testing, pulsed-field gel electrophoresis, multilocus sequence typing, plasmid typing, and β-lactamase identification. The OmpK35 and OmpK36 porins were analyzed by SDS-PAGE, and their genes were amplified and sequenced. Complementation experiments were performed using a recombinant unrelated ompK36 gene. An ertapenem-resistant and imipenem- and meropenem-susceptible clone was identified and assigned to the sequence type 37 lineage by MLST; it carried SHV-12 and CTX-M-15 ESBLs, did not produce the OmpK35 due to a nonsense mutation, and expressed a novel OmpK36 variant (OmpK36V). This variant showed two additional amino acids located within the L3 internal loop, one of the highly conserved domains of the protein. Two isolates of the same clone also exhibited resistance to imipenem and meropenem, due to the loss of OmpK36 expression by a nonsense mutation occurring in the ompK36V variant gene. These were the first carbapenem-resistant K. pneumoniae isolates identified within the hospital. Screening for the ompK36V gene of unrelated K. pneumoniae isolates derived from patients from 2006 to 2009 demonstrated the high frequency of this gene variant as well as its association with ertapenem resistance, reduced susceptibility to meropenem, and susceptibility to imipenem.

Successful Ertapenem-Doripenem Combination Treatment of Bacteremic Ventilator-Associated Pneumonia Due to Colistin-Resistant KPC-Producing Klebsiella pneumoniae

Severe infections caused by carbapenemase-producing Klebsiella pneumoniae are becoming a significant problem worldwide and are associated with high morbidity and mortality rates ([1][1][–][2][3][3]). Recently, treatments based on therapies with combinations of colistin, tigecycline, meropenem,

Risk factors and clinical significance of ertapenem-resistant Klebsiella pneumoniae in hospitalised patients

Ertapenem-resistant Klebsiella pneumoniae (ER-Kp) is an emerging healthcare-associated pathogen. In order to identify risk factors associated with ER-Kp acquisition, the records of 100 patients from whom K. pneumoniae had been isolated between July 2008 and December 2009 were reviewed. These comprised 38 with ER-Kp (28 infected, 10 colonised) and 62 with ertapenem-susceptible K. pneumoniae (ES-Kp) (43 infected, 19 colonised). Multilocus sequence typing (MSLT) and porin gene investigation performed on 25 ER-Kp strains showed that 24 belonged to the ST37 lineage, expressing a novel OmpK36 variant and not expressing OmpK35. Breakthrough bacteraemia occurred in 13 (52%) of 25 bloodstream infections (BSIs). Among nine ER-Kp BSIs, five were complicated by breakthrough bacteraemia, of which four developed during carbapenem therapy. Among 16 ES-Kp BSIs, breakthrough bacteraemia developed in eight patients (50%), but only one occurred (12%) during carbapenem therapy. Logistic regression analysis showed that carbapenems (odds ratio: 12.9; 95% confidence interval: 3.09-53.7; P < 0.001), second generation cephalosporins (11.8; 1.87-74.4; P < 0.01), endoscopy (5.59; 1.32-23.6; P < 0.02), acute renal failure (5.32; 1.13-25.1; P=0.034) and third generation cephalosporins (4.15; 1.09-15.8; P < 0.01) were independent risk factors for acquisition of ER-Kp. Our findings confirm that prior use of certain antimicrobials, specifically carbapenems and cephalosporins, are primary independent risk factors for colonisation or infection with ER-Kp.

Infections with VIM-1 Metallo-β-Lactamase-Producing Enterobacter cloacae and Their Correlation with Clinical Outcome

ABSTRACT The aim of this study was to ascertain the incidence and clinical significance of metallo-β-lactamases among Enterobacter strains isolated from patients with nosocomial infections. We prospectively collected data on patients with Enterobacter infection during a 13-month period. All of the strains were investigated for antibiotic susceptibility, the presence and expression of metallo-β-lactamases, and clonality. Of 29 infections (11 involving the urinary tract, 7 pneumonias, 3 skin/soft tissue infections, 3 intra-abdominal infections, 3 bacteremias, and 2 other infections), 7 (24%) were caused by Enterobacter cloacae strains harboring a blaVIM-1 gene associated or not with a blaSHV12 gene. Infections caused by VIM-1-producing strains were more frequently associated with a recent prior hospitalization (P = 0.006), cirrhosis (P = 0.03), relapse of infection (P < 0.001), and more prolonged duration of antibiotic therapy (P = 0.01) than were other infections. All of the isolates were susceptible to imipenem and meropenem and had blaVIM-1 preceded by a weak P1 promoter and inactivated P2 promoters. Most VIM-1-producing Enterobacter isolates belonged to a main clone, but four different clones were found. Multiclonal VIM-1-producing E. cloacae infections are difficult to diagnose due to an apparent susceptibility to various beta-lactams, including carbapenems, and are associated with a high relapse rate and a more prolonged duration of antibiotic therapy.

First Report of the Carbapenem-Hydrolyzing Oxacillinase OXA-58 in Acinetobacter baumannii Isolates in Italy

Emergence of Acinetobacter baumannii with resistance or reduced susceptibility to carbapenems has been reported worldwide ([4][1]). Acinetobacter may develop resistance to carbapenems through various mechanisms, including decreased permeability, efflux pump overexpression, and production of

Clostridium difficile 027 increasing detection in a teaching hospital in Rome, Italy

To the Editor,In a recent article, Guastalegname et al. [1] reported acluster of lethal fulminant healthcare-associated Clostrid-ium difficile colitis in a tertiary care hospital in Rome, Italy.All seven affected patients died, in four of them ribotypinganalysis was done and ribotype 027 was recognized.According to the authors, the high mortality rate could beattributed to the extent of disease severity induced by thestrain 027, the delay in antimicrobial therapy administra-tion, and the lack of efficacy of the standard antibiotic.Since 2002, the hypervirulent ribotype 027 strainresponsible for more severe C. difficile infections with anincreased risk of death widespread and several seriousoutbreaks have been reported mostly from North Americaand Europe [2]. A recent wide hospital-based surveythrough 34 European countries showed an overall 5 % PCRribotype 027 prevalence in the continent, but no cases werefound in Italy [3]. Undoubtedly epidemic cases reportedfrom Italy remain sporadic to date [4, 5].As epidemiological data are urgently needed in ourcountry to better characterize the spread of PCR ribotype027 C. difficile, we carried out a retrospective study in the1.100 bed teaching hospital ‘‘Umberto I’’ in Rome. Stoolsamples were tested using a two-step algorithm for C.difficile infection, an EIA test for Glutamate dehydrogenase(Immunocard C. difficile GDH Meridian Bioscience Eur-ope) detection followed by Xpert C. difficile (Cepheid) Epipolymerase chain reaction (PCR) assay which is a multi-plex real-time PCR that identifies presumptive 027 strainsbased on detection of the genes for toxin B (tcd B), binarytoxin gene (cdt) and a single base-pair (bp) deletion atposition 117 in the gene coding for the anti-sigma factortcdC.Over the period from August to December 2013, a totalof 430 consecutive fecal samples were collected from 308symptomatic patients (mean age 61.0 ± 24.9 years, med-ian 68, 54.2 % males, 45.8 % females) presenting diarrheaand clinical suspicion for C. difficile infection. GDH testresulted positive in 69 (22.4 %) patients (mean age68.5 ± 21.2 years, median 79). Xpert C. difficile assaycarried out on stools from these 69 patients indicated tcdgene deletion in 24 patients (46.1 %), presumably identi-fying 027 ribotype. The patients (11 males and 13 females)were older compared with those infected due to other C.difficile strains (75.6 ± 17.1 vs 64.7 ± 22.4; p = 0.042).Therefore, in our hospital 7.8 % of symptomatic patientstested for C. difficile presumably revealed 027 ribotype. Asthe 24 identified cases were admitted to 15 different wards,our data show that C. difficile 027 strain is now endemic inour teaching hospital, and probably in other hospitals inRome, where major risk factors for the microorganismcirculation as overcrowding, understaffing, high level ofantibiotic use, population aging and increasing severity ofcomorbidities are common.In conclusion, the epidemiological evidence from ourstudy highlights the recent extension of the 027 strain inRome and suggests the need for a multifaceted approachprevention. Surveillance by improved capacity of rapiddetection should lead to earlier treatment, better outcomeand control of outbreaks. Also antimicrobial stewardshipstrategies, isolation of symptomatic patients, adoption ofcontact precautions and reduction of C. difficile contami-nation of healthcare environmental surfaces should bestrongly encouraged in all healthcare settings [2].

Opsonic activity of intravenous immune globulin on Gram-negative bacteria exposed to a monobactam antibiotic

Abstract Sub-inhibitory concentrations of antibiotics can alter the morphology and structure of the bacterial surface leading to better opsonization and therefore enhanced phagocytosis. The opsonic activity of a standard intravenous immune gamma globulin (IVIG) was tested for control bacteria and bacteria grown in the presence of sub-minimal inhibitory concentration (sub-MIC) of aztreonam, and β-lactam antibiotic. IVIG enhanced uptake by polymorphonuclear leucocytes of five Gram-negative bacteria. This enhancement was further increased when bacteria were exposed to sub-MIC of aztreonam.

Correction to: A challenging case of carbapenemase-producing Klebsiella pneumoniae septic thrombophlebitis and right mural endocarditis successfully treated with ceftazidime/avibactam

IntroductionThe emergence of carbapenemase-producing Klebsiella pneumonia (KPC-Kp) has become a significant problem in terms of public health and clinical outcome in many hospitals in Southern Europe. Treatment options are usually limited and effective treatment of infections caused by these pathogens is a considerable challenge for clinicians. Ceftazidime–avibactam has been recently approved for the treatment of difficult-to-treat infections due to aerobic Gram-negative organisms in patients with limited treatment options.Case reportWe reported the first case of KPC-Kp septic thrombophlebitis and right atrial endocarditis associated with metastatic lung abscesses successfully treated with a prolonged ceftazidime/avibactam plus ertapenem treatment course, suggesting that this combination therapy could be safe and effective for serious Gram-negative infections. Interestingly, we also observed an apparent discrepancy between clinical and microbiological courses: the patient became rapidly afebrile; hemodynamically stable and his procalcitonin levels showed a prompt decreasing trend. Nevertheless, blood cultures remained persistently positive for a prolonged period.ConclusionIn conclusion, ceftazidime–avibactam plus ertapenem was a safe and effective therapy of serious endovascular infection due to KPC-Kp. Moreover, in this setting, follow-up blood cultures might represent an irreplaceable tool to guide the therapy.