Annarita Mazzariol

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.

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.

Contributions of the AmpC β-Lactamase and the AcrAB Multidrug Efflux System in Intrinsic Resistance of Escherichia coli K-12 to β-Lactams

ABSTRACT The roles of the AmpC chromosomal β-lactamase and the AcrAB efflux system in levels of intrinsic resistance and susceptibility ofEscherichia coli to β-lactams were studied with a set of isogenic strains. MICs of ureidopenicillins, carbenicillin, oxacillin, and cloxacillin were drastically reduced by the inactivation of AcrAB, whereas those of the earlier cephalosporins were affected mostly by the loss of AmpC β-lactamase.

AcrAB Efflux System: Expression and Contribution to Fluoroquinolone Resistance in Klebsiella spp.

ABSTRACT Seven Klebsiella pneumoniae and four Klebsiella oxytoca clinical isolates with different levels of resistance to ciprofloxacin were studied. Mutations in the topoisomerase genes were found in almost all strains, but the contribution of a multidrug efflux system homologous to AcrAB in Escherichia coli was also observed. Overexpression of this efflux system was demonstrated by immunoblotting with antibodies against E. coli AcrA.

Isolation from Blood Culture of a Leclercia adecarboxylata Strain Producing an SHV-12 Extended-Spectrum Beta-Lactamase

ABSTRACT We report on the first isolation of an extended-spectrum beta-lactamase-producing Leclercia adecarboxylata strain from the bloodstream in a 58-year-old man with acute myeloid leukemia. The strain, resistant to ceftazidime, cefotaxime, and aztreonam, produces the SHV-12 β-lactamase, one of the most common variants found in Italian nosocomial isolates of Enterobacteriaceae.

NDM-1-producing Klebsiella pneumoniae, Croatia.

To the Editor: The novel metallo-β-lactamase named New Delhi metallo-β-lactamase (NDM-1) was identified from Klebsiella pneumoniae and Escherichia coli isolates in Sweden from a patient previously hospitalized in India (1). NDM-1 is spreading rapidly worldwide to nonclonally related isolates, many of which are directly or indirectly tracked to the Indian subcontinent (2). A carbapenem-resistant K. pneumoniae strain, KLZA, was isolated in May 2009 from the culture of a blood sample from of a 40-year-old man on the day after his admission to a surgical intensive care unit of the Clinical Hospital Center in Zagreb, Croatia. The patient had been transferred after 5 days of hospitalization in Bosnia and Herzegovina following a car accident. The clinical history mentioned antimicrobial drug treatment that did not include carbapenems (gentamicin, metronidazole, and ceftriaxone) and no link to the Indian subcontinent. Antimicrobial drug susceptibility testing was performed by Vitek2 (bioMerieux, Marcy-l’Etoile, France) and broth microdilution and interpreted according to the latest documents from the European Committee on Antimicrobial Susceptibility Testing (www.eucast.org/clinical_breakpoints/, version 1.1). The strain proved resistant to imipenem and meropenem, to all broad-spectrum cephalosporins, and to aminoglycosides and susceptible to ciprofloxacin and tigecycline (Table). We checked for blaVIM, blaIMP, blaSPM, blaGIM, blaSIM, and blaNDM resistance genes by using PCR. A PCR product was obtained only with the NDM primers, after being purified (QIAquick PCR Purification Kit, QIAGEN, Hilden, Germany), its sequence showed 100% identity with blaNDM-1. Table MIC of the KLZA strain of Klebsiella pneumoniae and its transconjugant and recipient Strain genotyping was performed by multilocus sequence typing to determine the sequence type (ST) of the isolate and to establish a comparison with previously reported NDM-1–producing isolates. Allelic numbers were obtained on the basis of sequences of 7 housekeeping genes at www.pasteur.fr/recherche/genopole/PF8/mlst/Kpneumoniae.html. Multilocus sequence typing identified K. pneumoniae KLZA as an ST25 strain, which significantly differs from the ST14 type found in the index NDM-1–producing strain and from other isolates originating from India (1) and then in other countries. ST25 K. pneumoniae was also found in K. pneumoniae isolates in Geneva (3). Other K. pneumoniae STs harboring NDM-1 were ST15, ST16, and ST147 (4–7). Resistance was transferred by conjugation to E. coli J53, with selection based on growth on agar in the presence of ceftazidime (10 mg/L) and azide (100 mg/L). The conjugant T1 showed resistance to β-lactams, including all carbapenems, as well as decreased susceptibility to ciprofloxacin. The KLZA strain and its transconjugant harbored other determinant of resistance, namely blaCTX-M-15, blaCMY-16, and qnrA6. Plasmid incompatibility groups, determined by a PCR-based replicon typing method, belonged to the incA/C replicon type. This report of an NDM-1–producing K. pneumoniae in Croatia adds to those of other cases in patients from patients hospitalized in the Balkan area. The patient in this report had no apparent link to the Indian subcontinent. In a survey conducted by the European Centre for Disease Prevention and Control to gather information about the spread of NDM-1–producing Enterobacteriaceae in Europe and reporting cases from 13 countries during 2008–2010, five of the 55 persons with known travel histories had traveled to the Balkan region during the month before diagnosis of their infection: 2 to Kosovo and 1 each to Serbia, Montenegro, and Bosnia and Herzegovina. All had received hospital care in Balkan countries because of an illness or accident that occurred during the journey (7). Two of the latter cases (4,8) and a case from Germany (9) were subsequently published. No patient had any apparent link to the Indian subcontinent. Although the way NDM-1 isolates might have been imported to western Europe not only from the Indian subcontinent but also from Balkan countries (10) has been highlighted, awareness of western Europe as a possible area of endemicity remains limited. The aforementioned report from Germany, although recognizing that the patient had been repatriated after hospitalization in Serbia, declared “no evidence about contact with people from regions where NDM-enterobacteria are endemic” (9). This limited awareness shows the threat of neglecting to screen patients who are transferred from countries thought not to be at risk for NDM-1. Furthermore, it means that specimen are not sent to the local reference laboratories and recognized as positive for NDM-1, thus permitting wide dissemination of NDM-1–producing enterobacteria in the community (4). The accumulating evidence of NDM-1 from the Balkan area could suggest a possible multifocal spread of this enzyme, with the Balkans as a possible second area of endemicity, in addition to the Indian subcontinent, and prompts for widespread epidemiologic surveillance.

Resistance of Enterococci to Ampicillin and Glycopeptide Antibiotics in Italy

We report the results of the monitoring of resistance to ampicillin, vancomycin, and teicoplanin in enterococci by an Italian network of clinical microbiology laboratories. A total of 16,226 strains were analyzed; 9,169 of these strains were Enterococcus faecalis, 913 were Enterococcus faecium, and 6,144 were Enterococcus species. The average rate of resistance to ampicillin was 1.9% (range, 0-6.5%) for E. faecalis and 70% (range, 33.3%-98.7%) for E. faecium; the average rate of resistance to vancomycin was 1.1% (range, 0.1%-2%) for E. faecalis and 8.5% (range, 0-36.1%) for E. faecium; and the average rate of resistance to teicoplanin was 0.8% (range, 0-2.4%) for E. faecalis and 8.7% (range, 0-36.1%) for E. faecium.

Description and plasmid characterization of qnrD determinants in Proteus mirabilis and Morganella morganii

We investigated the presence of qnrC and qnrD among 756 non-replicate Enterobacteriaceae isolated in Italy, selected for being non-susceptible to fluoroquinolones and/or resistant to third-generation cephalosporins. Four Proteus mirabilis and one Morganella morganii (0.66% of the total) presented a qnrD gene, located in a 2687-base-pair plasmid that was entirely sequenced. The plasmid is un-typable, and contains no known coding region other than qnrD. That the qnrD gene was found in four unrelated P. mirabilis and in one M. morganii isolate might suggest a frequent association of this gene with the tribe Proteeae.

Molecular typing of erythromycin-resistant streptococcus pyogenes strains with the M phenotype isolated in Italy.

Abstract To assess the spread of the new M phenotype, various erythromycin-resistant Streptococcus pyogenes strains from three Italian cities (Verona, Monza, Florence) were characterised. Each strain was analysed for the presence of genes ermAM and mefA, for the ability to accumulate radioactive erythromycin in the absence of sodium arsenate, for the protein T serological type, and for the DNA macrorestriction profile identified by means of pulsed-field gel electrophoresis. In a number of strains, the presence of the inducible ermAM gene was demonstrated; all these strains were negative in the efflux-pump detection assay, did not possess the mefA gene, and had similar restriction profiles. The strains with the efflux mechanism and mefA gene belonged to different serotypes. Of these, only one serotype, T4, was isolated in all three cities. The restriction profile analysis with SmaI and SfiI revealed a very close correlation between strains with the same serotype.