Branka Bedenić

blaCTX-M Genes in Escherichia coli Strains from Croatian Hospitals Are Located in New (blaCTX-M-3a) and Widely Spread (blaCTX-M-3a and blaCTX-M-15) Genetic Structures

ABSTRACT CTX-M-producing Escherichia coli isolates from three Croatian hospitals were analyzed. All blaCTX-M-15 genes and one blaCTX-M-3a gene resided in widely spread ISEcp1 transposition modules, but other blaCTX-M-3a genes were in a new configuration with two IS26 copies, indicating a new event of gene mobilization from a Kluyvera ascorbata genome. The study confirmed the role of the E. coli ST131 clonal group with IncFII-type plasmids in the spread of blaCTX-M-15 and of IncL/M pCTX-M3-type plasmids in the dissemination of blaCTX-M-3a.

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.

Infrequent Finding of Metallo-β-Lactamase VIM-2 in Carbapenem-Resistant Pseudomonas aeruginosa Strains from Croatia

ABSTRACT One hundred sixty-nine nonreplicate imipenem-resistant Pseudomonas aeruginosa strains isolated in a large hospital on the coastal region of Croatia were studied. The most active antibiotics were colistin and amikacin. Most of the isolates were multiresistant. The most prevalent serotype was O12, followed by O11. Six strains carried the blaVIM-2 gene located in a novel class 1 integron composed in its variable part of the blaVIM-2-blaoxa-10-ΔqacF-aacA4 genes. Metallo-β-lactamase-producing strains belonged to sequence types ST235 and ST111.

First report of KPC-producing Klebsiella pneumoniae in Croatia

Abstract In February 2011, a 78-year-old male patient was admitted to Clinical Hospital Center Zagreb with subdural haematoma. Klebsiella pneumoniae with reduced susceptibility to carbapenems was isolated. PCR revealed the presence of blaKPC, blaTEM, and blaSHV genes. Sequencing of blaKPC gene identified K. pneumoniae carbapenemase (KPC)-2 beta-lactamase. The strain belonged to ST37 clone by multilocus sequence typing. Infection control efforts limited the spread of KPC-producing clone of K. pneumoniae in our hospital so far. To our knowledge, this is the first report of a KPC-producing K. pneumoniae in Croatia.

Clonal spread of carbapenem-resistant OXA-72-positive Acinetobacter baumannii in a Croatian university hospital

BACKGROUND From July to October 2008, 34 Acinetobacter baumannii isolates were involved in an outbreak at the Clinical Hospital Center, Zagreb. The aim of this study was to characterize the mechanisms of carbapenem resistance in our A. baumannii isolates and determine their epidemiology. METHODS Antibiotic susceptibilities were determined by broth microdilution. PCR was used to detect the presence of carbapenemases. Genotyping of the isolates was performed by random amplification of polymorphic DNA (RAPD), pulsed-field gel electrophoresis (PFGE), and repetitive sequence-based PCR (rep-PCR). RESULTS Thirty-three carbapenem-resistant isolates were positive for the acquired bla(OXA-72) and one unrelated isolate was positive for bla(OXA-58). The bla(OXA-72)-positive isolates were shown to be clonally related by RAPD, rep-PCR, and PFGE. CONCLUSIONS On the basis of susceptibility testing, β-lactamase characterization, and genotyping of the isolates we can conclude that clonal spread of endemic isolates was responsible for the high frequency of OXA-72-positive multidrug-resistant A. baumannii in this setting. Most of the isolates originated from the intensive care unit indicating local dissemination within the hospital and pointing to the potential source of isolates.

First report of molecular characterization of carbapenem-resistant Acinetobacter baumannii in different intensive care units in University Hospital Split, Croatia.

Acinetobacter baumannii is an important cause of nosocomial infections such as pneumonia, septicaemia, urinary tract infections, and wound infections 1. It may become resistant to a wide range of antibiotics, thus complicating the treatment of nosocomial infections 1. The emergence of carbapenem resistance in Acinetobacter baumannii has become a global concern since these β -lactams are often the only effective treatment left against many multiresistant strains . According to a recent report, the overall resistance rate to imipenem in A. baumannii isolated from 17 representative laboratories in Croatia was 1 % (range 0%-8%) . However, molecular basis of carbapenem resistance was not investigated yet. We would like to report the molecular epidemiology of carbapenem resistant strains obtained from clinical samples of several patients hospitalised on different intensive care units inside University Hospital Split, Croatia. Eleven isolates of A. baumannii with an unusual resistance profile were isolated during 2003 and 2004, from patients hospitalised in three different intensive care units (two adults and one children ICU) on different locations inside UHS. Routine susceptibility testing was done by standard disc diffusion method according to the National Committee for Clinical Laboratory Standards guidelines. All collected isolates of A. baumannii displayed intermediate (MICs>8 mg/L) or resistant (MICs>16 mg/L) profile to imipenem and/or meropenem. Minimum inhibitory concentrations were also determined for ceftazidime, cefepime, ceftriaxone, amikacin, gentamicin, ciprofloxacin and piperacillin-tazobactam by broth microdilution method according to CLSI recommendation.. All isolates were multidrug-resistant exhibiting highly resistance to ceftazidime, cefepime, piperacillin/tazobactam, amikacin, gentamicin, netilmicin and ciprofloxacin. No resistance to ampicillin/sulbactam was observed which is not in use in our hospital. The isolates were genetically characterized with pulsed-field gel electrophoresis (PFGE). The preparation of genomic DNA of A. baumannii isolates was performed as previously described. Oxacillinases were detected by using a standard PCR technique with primers specific for blaOXA-23, blaOXA-40, blaOXA-58, and blaOXA-69 genes. Production of metallo-β -lactamases was screened by E test-MBL and PCR with primers specific for VIM and IMP β -lactamases. Β -lactamases were prepared from overnight broth cultures, released by sonication and cell debris was removed by centrifugation. PCRs were positive for the OXA-69 like enzyme in ten Acinetobacter strains belonging to unique PFGE profile characterised to pulsotype A, while strain characterised to pusotype B was the only strain isolated from children intensive care unit and carbapenemase gene was not found with tested primers. No significant hydrolysis of imipenem was detected. Acccording to the bibliographical data OXA-69 is a naturally occurring oxacillinase in A. baumannii and it does not confer on the producing isolates significant resistance to carbapenems, thus it can be concluded that resistance to imipenem and meropenem in our isolates is due to other mechanisms such as porin loss or efflux. Spread of the pulsotype A with OXA-69-type oxacillinases was due to clonal dissemination of multi-drug resistant A. baumannii between two different adult Intensive Care Units, probably by hospital staff during medical procedures. The infection control team of the hospital implemented restriction of carbapenem usage and strict antiseptic techniques, which included the rigorous use of alcohol-clorhexidine solutions before and between patient and equipment contact and before leaving the unit. To our knowledge, this is the first report on the molecular characterization carbapenem resistance in A. baumannii in Croatia. A similar finding underscores the progressive emergence of these determinants in different geographic areas. Consequently, incidence and spread of multidrug-resistant A. baumannii nosocomial infections suggest the necessity of a surveillance program and enforcing adequate control measures in different hospital settings

Occurrence of OXA-107 and ISAba1 in Carbapenem-Resistant Isolates of Acinetobacter baumannii from Croatia

ABSTRACT Carbapenem-resistant isolates of Acinetobacter baumannii from intensive care units at Split University Hospital, Split, Croatia, were studied. Most (100 of 106) had ISAba1 inserted upstream of a blaOXA-107 gene, encoding an unusual OXA-51-type oxacillinase. Pulsed-field gel electrophoresis revealed that the isolates formed three clusters belonging to the sequence group 2 (European clone 1) lineage.

VIM-2 β-lactamase in Pseudomonas aeruginosa isolates from Zagreb, Croatia

Abstract The aim of this investigation was to characterize metallo-β-lactamases (MBLs) in Pseudomonas aeruginosa isolates from Zagreb, Croatia. One hundred P. aeruginosa isolates with reduced susceptibility to either imipenem or meropenem were tested for the production of MBLs by MBL-Etest. The susceptibility to a wide range of antibiotics was determined by broth microdilution method. The presence of blaMBL genes was detected by polymerase chain reaction (PCR). Hydrolysis of 0.1 mM imipenem by crude enzyme preparations of β-lactamases was monitored by UV spectrophotometer. Outer membrane proteins were prepared and analysed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Six out of 100 isolates were positive for MBLs by Etest. All strains were resistant to gentamicin, ceftazidime and cefotaxime, and all except 1 were resistant to imipenem. Six strains positive for MBLs by Etest were identified as VIM MBL-producers by PCR. Sequencing of blaVIM genes revealed the production of VIM-2 β-lactamase in all 6 strains. This investigation proved the occurrence of VIM-2 β-lactamase among P. aeruginosa strains from Zagreb, Croatia. VIM-2 β-lactamase with similar properties has previously been described in another region of Croatia and in Italy, France, Spain, Greece, Taiwan and South Korea, suggesting that this type of enzyme is widespread in the Mediterranean region of Europe and in the Far East.

Molecular characterization of class b carbapenemases in advanced stage of dissemination and emergence of class d carbapenemases in Enterobacteriaceae from Croatia.

Carbapenemases involved in acquired carbapenem resistance in Enterobacteriaceae belong to Ambler class A serin β-lactamases, class B metallo-β-lactamases (MBL) or class D OXA-48-like β-lactamases. The aim of the present study was to analyse the molecular epidemiology and the mechanisms and routes of spread of class B and class D carbapenemases in Croatia. In total 68 isolates were analyzed. Antibiotic susceptibility was determined by broth microdilution method. PCR was used to detect antibiotic-resistance genes. Genotyping was performed by rep-PCR and MLST. Sixty-five isolates were found to harbour VIM-1 carbapenemase, seven of which were positive also for NDM-1, while two strains harboured only NDM-1. OXA-48 was detected in three isolates, two of which coproduced VIM-1. Thirty-six strains possessed additional CTX-M-15 β-lactamase whereas 64 were positive for TEM-1. CMY was found in 18 Citrobacter freundii isolates and DHA-1 in one Enterobacter cloacae isolate. Four different plasmid-incompatibility groups were found: A/C, L/M, N and FIIAs. Unlike C. freundii and E. cloacae, Klebsiella pneumoniae showed high diversity of rep-PCR patterns. E. cloacae and C. freundii predominantly belonged to one large clone which was allocated to ST105 and ST24, respectively. Three different types of carbapenemases were identified showing the complexity of CRE in Croatia.

Epidemic and endemic spread of Klebsiella pneumoniae producing SHV-5 beta-lactamase in dubrava university hospital, Zagreb, Croatia

Abstract Plasmid-encoded resistance to broad-spectrum cephalosporins and aztreonam is becoming a widespread phenomenon in clinical medicine. These antibiotics are inactivated by an array of different extended-spectrum β-lactamases (ESBLs) which have evolved by point mutations of parental TEM or SHV β-lactamases. In a previous study conducted during 1994-1995, SHV-2, SHV-2a and SHV-5 β-lactamases were found among Klebsiella pneumoniae isolates in Dubrava University Hospital. High prevalence of ESBLs among K. pneumoniae strains in this hospital (20%) required further investigation. In this investigation, β-lactamases from 42 K. pneumoniae strains collected in 1997 and 15 in 2004 from Dubrava University Hospital, were characterized in order to study the evolution of plasmid-encoded resistance to extended-spectrum cephalosporins and aztreonam in that hospital over a prolonged study period. Susceptibility to antibiotics was determined by diskdiffusion and broth microdilution method. β-lactamases were characterized by isoelectric focusing, determination of hydrolysis of β-lactam substrates, polymerase chain reaction and sequencing of blaSHV genes. All K. pneumoniae strains and their Escherichia coli transconjugants produced β-lactamase with an isoelectric point of 8.2. Based on sequencing of blaSHV genes enzymes of all transconjugants were identified as SHV-5 β-lactamase which conferred on the producing isolates high level of ceftazidime and aztreonam resistance. In this study, an outbreak of nosocomial infections caused by SHV-5 producing K. pneumoniae was described in 1997 which evolved to endemic spread of SHV-5 producing K. pneumoniae due to multiple plasmid transfer in the Dubrava University Hospital. The strains from 1997 and 2004 were not clonally related. Hospital hygiene measures should be applied in order to control the spread of epidemic strains through the hospital wards and the consumption of the broad-spectrum cephalosporins needs to be restricted to reduce the selection pressure which enables the proliferation of ESBL producers in hospital.