First countrywide survey of acquired metallo-beta-lactamases in gram-negative pathogens in Italy

Epidemiology of β-Lactamase-Producing Pathogens

β-Lactam antibiotics have been widely used as therapeutic agents for the past 70 years, resulting in emergence of an abundance of β-lactam-inactivating β-lactamases. Although penicillinases in Staphylococcus aureus challenged the initial uses of penicillin, β-lactamases are most important in Gram-negative bacteria, particularly in enteric and nonfermentative pathogens, where collectively they confer resistance to all β-lactam-containing antibiotics. Critical β-lactamases are those enzymes whose genes are encoded on mobile elements that are transferable among species. Major β-lactamase families include plasmid-mediated extended-spectrum β-lactamases (ESBLs), AmpC cephalosporinases, and carbapenemases now appearing globally, with geographic preferences for specific variants. CTX-M enzymes include the most common ESBLs that are prevalent in all areas of the world. In contrast, KPC serine carbapenemases are present more frequently in the Americas, the Mediterranean countries, and China, whereas NDM metallo-β-lactamases are more prevalent in the Indian subcontinent and Eastern Europe. As selective pressure from β-lactam use continues, multiple β-lactamases per organism are increasingly common, including pathogens carrying three different carbapenemase genes. These organisms may be spread throughout health care facilities as well as in the community, warranting close attention to increased infection control measures and stewardship of the β-lactam-containing drugs in an effort to control selection of even more deleterious pathogens.

Italian nationwide survey on Pseudomonas aeruginosa from invasive infections: activity of ceftolozane/tazobactam and comparators, and molecular epidemiology of carbapenemase producers

Objectives

Pseudomonas aeruginosa is a major cause of severe healthcare-associated infections and often shows MDR phenotypes. Ceftolozane/tazobactam is a new cephalosporin/β-lactamase inhibitor combination with potent activity against P. aeruginosa. This survey was carried out to evaluate the susceptibility of P. aeruginosa, circulating in Italy, to ceftolozane/tazobactam and comparators and to investigate the molecular epidemiology of carbapenemase-producing strains.

Methods

Consecutive non-replicate P. aeruginosa clinical isolates (935) from bloodstream infections and lower respiratory tract infections were collected from 20 centres distributed across Italy from September 2013 to November 2014. Antimicrobial susceptibility testing was performed by broth microdilution and results were interpreted according to the EUCAST breakpoints. Isolates resistant to ceftolozane/tazobactam were investigated for carbapenemase genes by PCR, and for carbapenemase activity by spectrophotometric assay. WGS using an Illumina platform was performed on carbapenemase-producing isolates.

Results

Ceftolozane/tazobactam was the most active molecule, retaining activity against 90.9% of P. aeruginosa isolates, followed by amikacin (88.0% susceptibility) and colistin (84.7% susceptibility). Overall, 48 isolates (5.1%) were positive for carbapenemase genes, including blaVIM (n = 32), blaIMP (n = 12) and blaGES-5 (n = 4), while the remaining ceftolozane/tazobactam-resistant isolates tested negative for carbapenemase production. Carbapenemase producers belonged to 10 different STs, with ST175 (n = 12) and ST621 (n = 11) being the most common lineages. Genome analysis revealed different trajectories of spread for the different carbapenemase genes.

Conclusions

Ceftolozane/tazobactam exhibited potent in vitro activity against P. aeruginosa causing invasive infections in Italy. Carbapenemase production was the most common mechanism of resistance to ceftolozane/tazobactam.

Colonization of long-term care facility residents in three Italian Provinces by multidrug-resistant bacteria

Background

Rationale and aims of the study were to compare colonization frequencies with MDR bacteria isolated from LTCF residents in three different Northern Italian regions, to investigate risk factors for colonization and the genotypic characteristics of isolates. The screening included Enterobacteriaceae expressing extended-spectrum β-lactamases (ESβLs) and high-level AmpC cephalosporinases, carbapenemase-producing Enterobacteriaceae, Pseudomonas aeruginosa or Acinetobacter baumannii, methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE).

Methods

Urine samples and rectal, inguinal, oropharyngeal and nasal swabs were plated on selective agar; resistance genes were sought by PCR and sequencing. Demographic and clinical data were collected.

Results

Among the LTCF residents, 75.0% (78/104), 69.4% (84/121) and 66.1% (76/115) were colonized with at least one of the target organisms in LTCFs located in Milan, Piacenza and Bolzano, respectively. ESβL producers (60.5, 66.1 and 53.0%) were highly predominant, mainly belonging to Escherichia coli expressing CTX-M group-1 enzymes. Carbapenemase-producing enterobacteria were found in 7.6, 0.0 and 1.6% of residents; carbapemenase-producing P. aeruginosa and A. baumannii were also detected. Colonization by MRSA (24.0, 5.7 and 14.8%) and VRE (20.2, 0.8 and 0.8%) was highly variable. Several risk factors for colonization by ESβL-producing Enterobacteriaceae and MRSA were found and compared among LTCFs in the three Provinces. Colonization differences among the enrolled LTCFs can be partially explained by variation in risk factors, resident populations and staff/resident ratios, applied hygiene measures and especially the local antibiotic resistance epidemiology.

Conclusions

The widespread diffusion of MDR bacteria in LTCFs within three Italian Provinces confirms that LTCFs are an important reservoir of MDR organisms in Italy and suggests that future efforts should focus on MDR screening, improved implementation of infection control strategies and antibiotic stewardship programs targeting the complex aspects of LTCFs.

Chronic infection sustained by a Pseudomonas aeruginosa High-Risk clone producing the VIM-1 metallo-β-lactamase in a cystic fibrosis patient after lung transplantation

BACKGROUND

The significance of chronic lung infection by multidrug-resistant (MDR) pathogens in Cystic Fibrosis (CF) transplanted patients remains controversial, and the available information is overall limited. Here we describe the case of a chronic infection, sustained by a metallo-β-lactamase (MBL)-producing P. aeruginosa strain, in a CF patient following lung transplantation.

METHODS

Twelve P. aeruginosa isolates collected from a CF patient over a 15-years follow-up period after lung transplantation were analysed for their antibiotic susceptibility profile, MBL production and clonal relatedness. Available clinical and microbiological records were reviewed.

RESULTS

The transplanted CF patient was chronically infected by an MBL-producing P. aeruginosa strain which harboured a bla_VIM-1 determinant inserted into a novel class 1 integron. The strain exhibited an MDR phenotype and belonged to the globally widespread ST235 epidemic clonal lineage, which however is not a typical CF-associated epidemic clone. Despite the chronic infection, the long-term outcome of this patient during the post-transplant period was characterized by the absence of acute exacerbations and by a mostly stable pulmonary function.

CONCLUSIONS

This report provides one of the few descriptions of MBL-producing P. aeruginosa infections in CF patients, and the first description of such an infection after lung transplantation in these patients. Infection with the MBL-producing strain apparently did not significantly affect the patient pulmonary function.

Infections Caused by Antimicrobial Drug-Resistant Saprophytic Gram-Negative Bacteria in the Environment

Background

Drug-resistance genes found in human bacterial pathogens are increasingly recognized in saprophytic Gram-negative bacteria (GNB) from environmental sources. The clinical implication of such environmental GNBs is unknown.

Objectives

We conducted a systematic review to determine how often such saprophytic GNBs cause human infections.

Methods

We queried PubMed for articles published in English, Spanish, and French between January 2006 and July 2014 for 20 common environmental saprophytic GNB species, using search terms “infections,” “human infections,” “hospital infection.” We analyzed 251 of 1,275 non-duplicate publications that satisfied our selection criteria. Saprophytes implicated in blood stream infection (BSI), urinary tract infection (UTI), skin and soft tissue infection (SSTI), post-surgical infection (PSI), osteomyelitis (Osteo), and pneumonia (PNA) were quantitatively assessed.

Results

Thirteen of the 20 queried GNB saprophytic species were implicated in 674 distinct infection episodes from 45 countries. The most common species included Enterobacter aerogenes, Pantoea agglomerans, and Pseudomonas putida. Of these infections, 443 (66%) had BSI, 48 (7%) had SSTI, 36 (5%) had UTI, 28 (4%) had PSI, 21 (3%) had PNA, 16 (3%) had Osteo, and 82 (12%) had other infections. Nearly all infections occurred in subjects with comorbidities. Resistant strains harbored extended-spectrum beta-lactamase (ESBL), carbapenemase, and metallo-β-lactamase genes recognized in human pathogens.

Conclusion

These observations show that saprophytic GNB organisms that harbor recognized drug-resistance genes cause a wide spectrum of infections, especially as opportunistic pathogens. Such GNB saprophytes may become increasingly more common in healthcare settings, as has already been observed with other environmental GNBs such as Acinetobacter baumannii and Pseudomonas aeruginosa.

Acquired metallo-β-lactamases and their genetic association with class 1 integrons and ISCR elements in Gram-negative bacteria

ABSTRACT 

Metallo-β-lactamases (MBLs) can hydrolyze almost all β-lactam antibiotics and are resistant to clinically available β-lactamase inhibitors. Numerous types of acquired MBLs have been identified, including IMP, VIM, NDM, SPM, GIM, SIM, DIM, KHM, TMB, FIM and AIM. IMPs and VIMs are the most frequent MBLs and disseminate in members of the family Enterobacteriaceae, Pseudomonas spp. and Acinetobacter spp. Acquired MBL genes are often embedded in integrons, and some are associated with insertion sequence (IS) elements. The class 1 integrons and IS common region (ISCR) elements are usually harbored in transposons and/or plasmids, forming so-called mobile vesicles for horizontal transfer of captured genes between bacteria. Here, we review the MBL superfamily identified in Gram-negative bacteria, with an emphasis on the phylogeny of acquired MBLs and their genetic association with class 1 integrons and IS common region elements.

Tn6249, a new Tn6162 transposon derivative carrying a double-integron platform and involved with acquisition of the blaVIM-1 metallo-β-lactamase gene in Pseudomonas aeruginosa

The In70.2 integron platform appears to be a conserved structure involved in the dissemination of the blaVIM-1 metallo-β-lactamase gene in Pseudomonas aeruginosa. The genetic context of the In70.2 integron platform from P. aeruginosa VR-143/97, the VIM-1-producing index strain isolated in Italy in 1997, was fully characterized by a next-generation sequencing approach refined by conventional sequencing. The In70.2 integron platform from VR-143/97 was found to be associated with a defective Tn402-like transposon inserted into the urf2 gene of a Tn3 family transposon of an original structure, named Tn6249, which also carried a partially deleted mer operon and an In90 integron platform in a tail-to-tail orientation. Tn6249 was inserted into a PACS171b-like genomic island, which was in turn inserted into the endA gene of the Pseudomonas chromosomal backbone. Tn6249 showed a similar structure and a conserved location with respect to that of Tn6060, a Tn3 family transposon associated with In70.2 and carrying a double-integron platform, which was detected in a VIM-1-producing P. aeruginosa strain isolated in Australia in 2008. Both Tn6249 and Tn6060 are apparently derived from Tn6162, a mercury resistance transposon carrying an integron platform, which was found in P. aeruginosa isolates from different geographic locations. The conservation of the genetic context of Tn6249 and Tn6060 suggests an in situ evolution of these elements after the insertion of a Tn6162-like ancestor into the PACS171b-like genomic island (GI) present in the genome of a successful widespread P. aeruginosa clonal lineage.

MLST reveals potentially high-risk international clones of Enterobacter cloacae

OBJECTIVES

To perform the first multinational Enterobacter cloacae clonality study, using the MLST scheme newly developed in Japan.

METHODS

The analysis included 195 rectal carriage E. cloacae isolates resistant to expanded-spectrum cephalosporins (ESCs), collected from patients in 12 hospital units across Europe and Israel. All of the isolates were typed by PFGE and 173 isolates were subjected to MLST. ESC resistance was analysed phenotypically; genes encoding ESBLs and carbapenemases were identified by PCR and sequencing.

RESULTS

MLST distinguished 88 STs, which correlated with the PFGE data. PFGE was more discriminatory, producing 129 pulsotypes (169 patterns). Numerous STs were observed in several countries each. The most widespread were ST66, ST78, ST108 and ST114, each having at least 10 isolates from three to five countries, diversified into multiple pulsotypes, with clusters of related isolates in one or more centres. Analysis of the STs against the MLST database revealed several epidemic clonal complexes, such as those with central genotypes ST74 (including ST78) or ST114 (including ST66). ESC resistance was equally related to overexpression of the AmpC cephalosporinase and to ESBL production. Among ESBL producers some spreading subclones were identified, including specific ST66, ST78 and ST114 pulsotypes, associated with CTX-M-15 production. Several isolates produced carbapenemase VIM-1 or KPC-2.

CONCLUSIONS

Together with the information available in the MLST database, our results suggest that, like Escherichia coli and Klebsiella pneumoniae, E. cloacae harbours clonal lineages of increased epidemic potential that may be associated with resistance spread.

An outbreak of extremely drug-resistant Pseudomonas aeruginosa in a tertiary care pediatric hospital in Italy

Background

Extensively drug-resistant Pseudomonas aeruginosa (XDR-PA) isolates are susceptible to only one or two classes of antibiotics. In 2011–2012, we investigated an outbreak of XDR-PA affecting children with onco-hematological diseases.

Methods

Outbreak investigation included ascertainment of cases, tracing of intestinal carriers and environmental surveillance. Contact precautions were adopted for patients with infection or colonization. Isolates were tested for antimicrobial susceptibility; phenotypic confirmation of carbapenemase production was performed, and carbapenemase genes were tested by multiplex polymerase-chain-reaction (PCR). Genotypes were determined by pulsed-field gel electrophoresis (PFGE).

Results

XDR-PA was isolated from 27 patients; 12 had bacteremia, 6 other infections and 9 were colonized. Severe neutropenia was significantly associated with bacteremia. Bloodstream-infection mortality rate was 67%. All isolates were resistant to carbapenems, cephalosporins and penicillins + β-lactamase inhibitors. Isolates were susceptible only to colistin in 22 patients, to colistin and amikacin in 4, and to ciprofloxacin and colistin in 1. PFGE results identified 6 subtypes of a single genotype, associated with clusters of cases, and 4 sporadic genotypes. Two sporadic isolates were metallo-β-lactamase producers, negative to PCR. All other isolates were metallo-β-lactamase producers due to the presence of a VIM carbapenemase. Incidence of XDR-PA infections decreased from 0.72 cases/1,000 inpatient-days in March 2011-March 2012, to 0.34/1,000 in April-December 2012, after implementation of active finding of intestinal carriers on all onco-hematological inpatients.

Conclusions

Control measures targeting intestinal carriers are crucial in limiting in-hospital transmission of XDR-PA polyclonal strains, protecting more vulnerable patients, such as severely neutropenic children, from developing clinical infections.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2334-14-494) contains supplementary material, which is available to authorized users.

An outbreak of extremely drug-resistant Pseudomonas aeruginosa in a tertiary care pediatric hospital in Italy

BACKGROUND

Extensively drug-resistant Pseudomonas aeruginosa (XDR-PA) isolates are susceptible to only one or two classes of antibiotics. In 2011-2012, we investigated an outbreak of XDR-PA affecting children with onco-hematological diseases.

METHODS

Outbreak investigation included ascertainment of cases, tracing of intestinal carriers and environmental surveillance. Contact precautions were adopted for patients with infection or colonization. Isolates were tested for antimicrobial susceptibility; phenotypic confirmation of carbapenemase production was performed, and carbapenemase genes were tested by multiplex polymerase-chain-reaction (PCR). Genotypes were determined by pulsed-field gel electrophoresis (PFGE).

RESULTS

XDR-PA was isolated from 27 patients; 12 had bacteremia, 6 other infections and 9 were colonized. Severe neutropenia was significantly associated with bacteremia. Bloodstream-infection mortality rate was 67%. All isolates were resistant to carbapenems, cephalosporins and penicillins + β-lactamase inhibitors. Isolates were susceptible only to colistin in 22 patients, to colistin and amikacin in 4, and to ciprofloxacin and colistin in 1. PFGE results identified 6 subtypes of a single genotype, associated with clusters of cases, and 4 sporadic genotypes. Two sporadic isolates were metallo-β-lactamase producers, negative to PCR. All other isolates were metallo-β-lactamase producers due to the presence of a VIM carbapenemase. Incidence of XDR-PA infections decreased from 0.72 cases/1,000 inpatient-days in March 2011-March 2012, to 0.34/1,000 in April-December 2012, after implementation of active finding of intestinal carriers on all onco-hematological inpatients.

CONCLUSIONS

Control measures targeting intestinal carriers are crucial in limiting in-hospital transmission of XDR-PA polyclonal strains, protecting more vulnerable patients, such as severely neutropenic children, from developing clinical infections.

Sequence types 235, 111, and 132 predominate among multidrug-resistant pseudomonas aeruginosa clinical isolates in Croatia

A population analysis of 103 multidrug-resistant Pseudomonas aeruginosa isolates from Croatian hospitals was performed. Twelve sequence types (STs) were identified, with a predominance of international clones ST235 (serotype O11 [41%]), ST111 (serotype O12 [15%]), and ST132 (serotype O6 [11%]). Overexpression of the natural AmpC cephalosporinase was common (42%), but only a few ST235 or ST111 isolates produced VIM-1 or VIM-2 metallo-β-lactamases or PER-1 or GES-7 extended-spectrum β-lactamases.

Epidemiology and carbapenem resistance mechanisms of carbapenem-non-susceptible Pseudomonas aeruginosa collected during 2009-11 in 14 European and Mediterranean countries

OBJECTIVES

To evaluate the genetic relatedness and carbapenem resistance mechanisms among carbapenem-non-susceptible Pseudomonas aeruginosa collected during 2009-11 in 14 European and Mediterranean countries.

METHODS

Doripenem-non-susceptible (MIC >2 mg/L) isolates were tested for susceptibility to imipenem, meropenem, doripenem, aztreonam, ceftazidime and cefepime with and without phenyl-arginine-β-naphthylamide (PAβN) (efflux inhibitor) and/or cloxacillin (AmpC inhibitor). Carbapenemase screening was performed by PCR and sequencing. Expression of chromosomal ampC, mexA, mexC, mexE and mexX was determined by quantitative real-time PCR using P. aeruginosa PAO1 or a group of susceptible isolates as baseline. Clonality was evaluated by PFGE and multilocus sequence typing.

RESULTS

Among 529 (25.6% overall) carbapenem-non-susceptible P. aeruginosa, 106 were positive for metallo-β-lactamase (MβL) genes encoding VIM-2 (76 strains), VIM-4 (14), VIM-1 (7) and VIM-5 (5). IMP-15 and three new MβLs (IMP-33, VIM-36 and VIM-37) were detected in one strain each. An increasing prevalence of MβL producers was noted in 2011 (30.6%) compared with previous years (13.4% and 12.3% in 2009 and 2010, respectively). Isolates displayed high genetic diversity, with 401 unique profiles detected. CC235 and ST111 were detected among MβL-producing clusters. The PAβN/cloxacillin effect ranged from 90.0% to 56.5%/from 1.3% to 21.2%. OprD decrease/loss was the most prevalent intrinsic mechanism and was detected among 94.9% of the P. aeruginosa, followed by AmpC (44.4%) and MexAB-OprM (20.1%). When using the susceptible group of isolates as baseline, MexAB-OprM became as prevalent as OprD decrease/loss.

CONCLUSIONS

Increasing MβL prevalence is worrisome in various European countries; however, intrinsic resistance mechanisms in a highly genetically diverse population of carbapenem-non-susceptible P. aeruginosa are probably a matter for greater concern in these countries.

Carbapenemase-producing Pseudomonas aeruginosa from central Greece: molecular epidemiology and genetic analysis of class I integrons

Background

Multidrug-resistant Pseudomonas aeruginosa is a serious challenge for antimicrobial therapy of nosocomial infections, as it possesses several mechanisms of antimicrobial resistance. In Central Greece, a sudden increase of infections caused by carbapenem-resistant P. aeruginosa was observed during 2011, indicating the need for further analysis.

Methods

Five-hundred and sixty-eight P. aeruginosa isolates were collected consecutively during an 8-month period in 2011 from inpatients treated in three hospitals in the Thessaly region (1,000,000 habitants) of Greece. Carbapenem-resistant P. aeruginosa (n = 284) were characterized by antimicrobial susceptibility testing and β-lactamase content, and the genetic relatedness of carbapenemase-producing isolates was assessed by BOX-PCR, multilocus sequence typing, and eBURST analysis. Mapping of the class I integrons of Verona integron-encoded metallo-β-lactamase (VIM)-carrying isolates was also performed, and clinical data of the VIM producers were reviewed.

Results

Eighty (14.1%) out of the 568 P. aeruginosa isolates recovered from clinical specimens were VIM producers. Multilocus sequence typing revealed high prevalence of the international clones ST111 and ST235 among blaVIM-2- and blaVIM-4-positive isolates, respectively. blaVIM-17 was identified in an isolate of a novel sequence type (ST1457). bla_VIM gene cassettes were carried by five distinct class I integrons, including two novel ones.

Conclusions

Since the first report of VIM-producing P. aeruginosa in 2000, this microorganism still remains among the most prevalent multidrug resistant pathogens in Greece. The spread of VIM-producers belonging to the most common international clones (ST111 and ST235), the spread of integrons of divergent structures, and the emergence of novel integrons underscore their ongoing evolution.

Carbapenemase-producing Enterobacteriaceae in Europe: a survey among national experts from 39 countries, February 2013

The spread of carbapenemase-producing Enterobacteriaceae (CPE) is a threat to healthcare delivery, although its extent differs substantially from country to country. In February 2013, national experts from 39 European countries were invited to self-assess the current epidemiological situation of CPE in their country. Information about national management of CPE was also reported. The results highlight the urgent need for a coordinated European effort on early diagnosis, active surveillance, and guidance on infection control measures.

Molecular epidemiology and multidrug resistance mechanisms of Pseudomonas aeruginosa isolates from Bulgarian hospitals

A panel of 29 multidrug-resistant (MDR) Pseudomonas aeruginosa isolates recovered from seven hospitals as part of a country-wide surveillance of antimicrobial resistance in Bulgarian hospitals was studied. Molecular typing through multiple-locus variable number tandem-repeat analysis (MLVA6) yielded 23 different profiles. Phenotypic and genotypic tests for the detection of acquired carbapenemases yielded negative results in all cases. In contrast, 76% of the isolates produced other acquired β-lactamases, including extended-spectrum β-lactamases (ESBLs). Namely, 6 of the isolates (21%) produced a VEB-1 ESBL; 14 (48%) produced an OXA-10-type enzyme (7 OXA-10 and 7 OXA-10 ESBL variants, including 2 OXA-17 [A218G], 2 OXA-74 [C197T, A218G], and 3 OXA-142 [A218G, G470A]); 8 (28%) an OXA-2-type enzyme (all OXA-2); and 1 (3%) a PSE-1 carbenicillinase. Further analysis through multilocus sequence typing (MLST) revealed that the six VEB-1-producing strains, recovered from four hospitals, belonged to ST111 or ST244 international high-risk clones. Additionally, nearly all of the isolates (97%) lacked OprD production, explaining carbapenem resistance. Overexpression of AmpC was documented in 5 (17%) of the isolates, including most of the MDR isolates not producing any acquired β-lactamase. Particularly noteworthy was the very high prevalence of MexXY-OprM overexpression, documented in 72% of the isolates, whereas the prevalence of MexAB-OprM overexpression was lower (21%). In summary, while the production of metallo-β-lactamases is uncommon among P. aeruginosa isolates from Bulgarian hospitals, MDR profiles frequently result from the production of ESBLs combined with the lack of production of the carbapenem porin OprD and the overexpression of the MexXY-OprM efflux pump.

VIM-2-producing multidrug-resistant Pseudomonas aeruginosa ST175 clone, Spain

This clone is a major public health problem because it limits antimicrobial drug therapy.

A total of 183 patients were colonized or infected with multidrug-resistant Pseudomonas aeruginosa isolates at a hospital in Spain during 2007–2010; prevalence increased over this period from 2.8% to 15.3%. To characterize these isolates, we performed molecular epidemiologic and drug resistance analysis. Genotyping showed that 104 (56.8%) isolates belonged to a single major clone (clone B), which was identified by multilocus sequence typing as sequence type (ST) 175. This clone was initially isolated from 5 patients in 2008, and then isolated from 23 patients in 2009 and 76 patients in 2010. PCR analysis of clone B isolates identified the bla_VIM-2 gene in all but 1 isolate, which harbored bla_IMP-22. ST175 isolates were susceptible to only amikacin (75%) and colistin (100%). Emergence of the ST175 clone represents a major health problem because it compromises therapy for treatment of P. aeruginosa nosocomial infections.

Occurrence of IMP-8, IMP-10, and IMP-13 metallo-β-lactamases located on class 1 integrons and other extended-spectrum β-lactamases in bacterial isolates from Tunisian rivers

BACKGROUND

Antibiotic-resistant bacteria have been surveyed widely in water bodies, but few studies have determined the diversity of antibiotic-resistant bacteria in river waters. This study was undertaken to investigate the origin of resistance among polluted river bacterial isolates in Tunisia.

METHODS

In this study 128 isolates resistant to β-lactam antibiotics were obtained from 2 polluted rivers in the north of Tunisia. Isolates were identified using Phoenix phenotyping criteria. The occurrence of bla(TEM), bla(SHV), bla(CTX-M), bla(CMY), bla(VIM), and bla(IMP) was studied by polymerase chain reaction (PCR) amplification and sequencing, and the genetic relatedness of the 16 IMP-producing Klebsiella pneumoniae isolates was analyzed by comparison of XbaI pulsed-field gel electrophoresis (PFGE) profiles.

RESULTS

Using Phoenix phenotyping criteria, diverse genera of bacteria were identified with different rates of prevalence and with different minimum inhibitory concentrations against different antibiotics. The occurrence of bla(TEM), bla(SHV), bla(CTXM), bla(CMY), bla(VIM), and bla(IMP) genes was confirmed. The DNA sequences upstream and downstream of bla(IMP) genes were determined, revealing that all IMP-encoding genes constituted the first cassette of class 1 integrons, followed by aacA gene cassettes encoding aminoglycoside resistance. Comparison of PFGE profiles showed that only 2 of the isolates were clonal, the other 14 displaying unique profiles. The bla(CTX-M) gene was the most dominant of the extended-spectrum β-lactamase (ESBL) genes, while the bla(TEM) gene was the second-most dominant.

CONCLUSION

The discovery of highly diverse ESBL-producing bacteria and metallo-β-lactamases, particularly bla(IMP), in polluted river water raises alarms with regard to the potential dissemination of antibiotic-resistant bacteria in communities through river environments.

Rapid evolution and spread of carbapenemases among Enterobacteriaceae in Europe

Plasmid-acquired carbapenemases in Enterobacteriaceae, which were first discovered in Europe in the 1990s, are now increasingly being identified at an alarming rate. Although their hydrolysis spectrum may vary, they hydrolyse most β-lactams, including carbapenems. They are mostly of the KPC, VIM, NDM and OXA-48 types. Their prevalence in Europe as reported in 2011 varies significantly from high (Greece and Italy) to low (Nordic countries). The types of carbapenemase vary among countries, partially depending on the cultural/population exchange relationship between the European countries and the possible reservoirs of each carbapenemase. Carbapenemase producers are mainly identified among Klebsiella pneumoniae and Escherichia coli, and still mostly in hospital settings and rarely in the community. Although important nosocomial outbreaks with carbapenemase-producing Enterobacteriaceae have been extensively reported, many new cases are still related to importation from a foreign country. Rapid identification of colonized or infected patients and screening of carriers is possible, and will probably be effective for prevention of a scenario of endemicity, as now reported for extended-spectrum β-lactamase (mainly CTX-M) producers in all European countries.

Infrequent finding of metallo-β-lactamase VIM-2 in carbapenem-resistant Pseudomonas aeruginosa strains from Croatia

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 bla(VIM-2) gene located in a novel class 1 integron composed in its variable part of the bla(VIM-2)-bla(oxa-10)-ΔqacF-aacA4 genes. Metallo-β-lactamase-producing strains belonged to sequence types ST235 and ST111.

Microbiology at first visit of moderate-to-severe diabetic foot infection with antimicrobial activity and a survey of quinolone monotherapy

Samples from 1295 patients with diabetic foot infection were evaluated; 4332 samples were collected with an average of 3.3 samples per patient. Fifty-seven percent of patients had a 2B ulcer and 23% had a 3B ulcer according to Texas University Classification. In 64.2% of samples collected at first visit an etiologic agent was identified. About 40% of the positive samples were polymicrobial. Gram positive bacteria were more frequently isolated (52.6%), Staphylococcus aureus was the most frequently isolated single agent (29.9%) and MRSA was 22% of S. aureus. Enterococcus spp., mainly Enterococcus faecalis, were 9.9%, all vancomycin susceptible except 2 isolates. Streptococci were 4.6%, more than 60% Streptococcus agalactiae. Gram negative rods were 40.6%, with enterobacteria 23.5% and Pseudomonas aeruginosa 10.3%. Anaerobes were only 0.3%, probably due to culture methods applied in our laboratory. Cotrimoxazole, rifampin and doxycycline were still active against S. aureus. ESBL producers, among enterobacteria, were 10%, mainly Escherichia coli and Proteus spp. Only colistin had a rate of susceptibility against P. aeruginosa above 90%. Levofloxacin had the best clinical activity with respect to the other quinolones, but when it failed, selected more resistant strains with respect to moxifloxacin among S. aureus and with respect to ciprofloxacin among P. aeruginosa.

Antimicrobial susceptibilities and bacteriological characteristics of bovine Pseudomonas aeruginosa and Serratia marcescens isolates from mastitis

The presence of metallo-β-lactamase (MBL)-producing and multidrug-resistant Pseudomonas aeruginosa (MDRP) strains among bovine isolates of Gram-negative bacilli, and O-serotypes of bovine Serratia marcescens and P. aeruginosa isolates have been reported rarely. The aims of this study were to (1) elucidate antimicrobial susceptibilities and O-serotypes of P. aeruginosa and S. marcescens isolates from bovine mastitis and the presence of MBL-producers and MDRP strains among them and (2) evaluate their relationships to human isolates. We investigated the MICs of 24 antimicrobials and O-serotypes for 116 P. aeruginosa and 55 S. marcescens isolates in Japan, primarily in 2006. A total of 171 isolates exhibited high antimicrobial susceptibilities with the exception of a partial drug. P. aeruginosa isolates exhibited high susceptibilities of ≥ 95.7% to ciprofloxacin, imipenem, meropenem, piperacillin, ceftazidime, cefepime, cefoperazone/sulbactam, amikacin, tobramycin, and gentamicin; however, they exhibited a susceptibility of only 69.8% to aztreonam. They exhibited substantial resistances to ceftriaxone, enrofloxacin, cefotaxime, and moxalactam. S. marcescens isolates exhibited high susceptibilities of ≥ 90.9% to kanamycin, ceftiofur, sulfamethoxazole-trimethoprim, and the 15 aforementioned drugs, but exhibited resistance to minocycline. Neither MBL-producers nor MDRP strains were detected among the 171 strains. The dominant serotypes of P. aeruginosa isolates were OG, OA, OB, OI, OF, OE, and OK; those of S. marcescens isolates were O6 and O5. Every S. marcescens isolate was pigmented. These findings suggest that bovine P. aeruginosa and S. marcescens isolates differ from human isolates from both antibiogram and phenotypic perspectives, and could help to evaluate differences in bacteriological characteristics between bovine and human isolates.

Pseudomonas aeruginosa infection in cystic fibrosis caused by an epidemic metallo-β-lactamase-producing clone with a heterogeneous carbapenem resistance phenotype

An epidemic IMP-13 metallo-β-lactamase (MBL)-producing Pseudomonas aeruginosa clone, causing infections and even large outbreaks in Italian critical care settings, was detected in a young cystic fibrosis patient. In this patient, the chronic infection was sustained by distinct clonal sub-populations of the MBL-producing P. aeruginosa clone, either susceptible or resistant to carbapenems. These findings underscore the importance of infection prevention practices in cystic fibrosis settings and pose an important diagnostic and therapeutic challenge.

Epidemiology and genetics of VIM-type metallo-β-lactamases in Gram-negative bacilli

Metallo-β-lactamases (MBLs) are a rapidly evolving group of β-lactamases, which hydrolyze most β-lactams including the carbapenems. Of the known MBLs, VIMs are one of the most common families, with 27 variants detected in at least 23 species of Gram-negative bacilli from more than 40 countries/regions. The amino acid similarities of VIM variants range from 72.9 to 99.6% with 1–72 different residues. Most of the bla VIMs are harbored by a class 1 integron, a genetic platform able to acquire and express gene cassettes. The integrons are usually embedded in transposons and, in turn, accommodated on plasmids, making them highly mobile. Integrons display considerable diversity, with at least 110 different structures associated with the gain and spread of the bla VIMs. In most instances, the bla VIMs co-exist with one or more other resistance genes. The processes for the identification of bacteria harboring bla VIMs are also discussed in this article.

Overexpression of AmpC and efflux pumps in Pseudomonas aeruginosa isolates from bloodstream infections: prevalence and impact on resistance in a Spanish multicenter study

The prevalence and impact of the overexpression of AmpC and efflux pumps were evaluated with a collection of 190 Pseudomonas aeruginosa isolates recovered from bloodstream infections in a 2008 multicenter study (10 hospitals) in Spain. The MICs of a panel of 13 antipseudomonal agents were determined by microdilution, and the expressions of ampC, mexB, mexY, mexD, and mexF were determined by real-time reverse transcription (RT)-PCR. Up to 39% of the isolates overexpressed at least one of the mechanisms. ampC overexpression (24.2%) was the most prevalent mechanism, followed by mexY (13.2%), mexB (12.6%), mexF (4.2%), and mexD (2.2%). The overexpression of mexB plus mexY, documented for 5.3% of the isolates, was the only combination showing a significantly (P=0.02) higher prevalence than expected from the frequencies of the individual mechanisms (1.6%). Additionally, all imipenem-resistant isolates studied (25 representative isolates) showed inactivating mutations in oprD. Most of the isolates nonsusceptible to piperacillin-tazobactam (96%) and ceftazidime (84%) overexpressed ampC, while mexB (25%) and mexY (29%) overexpressions gained relevance among cefepime-nonsusceptible isolates. Nevertheless, the prevalence of mexY overexpression was highest among tobramycin-nonsusceptible isolates (37%), and that of mexB was highest among meropenem-nonsusceptible isolates (33%). Regarding ciprofloxacin-resistant isolates, besides the expected increased prevalence of efflux pump overexpression, a highly significant link to ampC overexpression was documented for the first time: up to 52% of ciprofloxacin-nonsusceptible isolates overexpressed ampC, sharply contrasting with the 24% documented for the complete collection (P<0.001). In summary, mutation-driven resistance was frequent in P. aeruginosa isolates from bloodstream infections, whereas metallo-β-lactamases, detected in 2 isolates (1%) producing VIM-2, although with increasing prevalences, were still uncommon.

Purification and biochemical characterization of IMP-13 metallo-beta-lactamase

The IMP-13 metallo-β-lactamase was overproduced in Escherichia coli BL21(DE3) and purified by chromatography. Analysis of kinetic parameters revealed some notable differences with other IMP-type enzymes, noteworthily a higher catalytic efficiency toward ticarcillin and piperacillin and a marked preference for imipenem over meropenem.

Complete nucleotide sequence of the IncN plasmid pKOX105 encoding VIM-1, QnrS1 and SHV-12 proteins in Enterobacteriaceae from Bolzano, Italy compared with IncN plasmids encoding KPC enzymes in the USA

OBJECTIVES

We determined the complete nucleotide sequence of pKOX105, a 54 641 bp plasmid from a Klebsiella oxytoca strain that was isolated from a resident of a long-term-care facility in Bolzano, Italy.

METHODS

The plasmid was sequenced using a shotgun approach. Combinatorial PCRs, directed PCRs and walking reads were used to assemble the contigs and to fill in gaps. Gene sequences were compared with reference plasmids and aligned with GenBank data using BLAST and CLUSTAL W software.

RESULTS

pKOX105 belonged to incompatibility group IncN, harboured bla(VIM-1), bla(SHV-12), qnrS1, aacA4 and dfrA14 and conferred resistance to carbapenems, oxyimino-cephalosporins, quinolones, aminoglycosides and trimethoprim. It was highly related to the p9 and p12 plasmids from Klebsiella pneumoniae and K. oxytoca strains isolated at a New York City hospital in 2005 carrying bla(KPC-2) and bla(KPC-3), respectively.

CONCLUSIONS

IncN plasmids are broad host-range plasmids that have contributed significantly to the worldwide dissemination of many different resistance genes in Enterobacteriaceae from animal and human sources. This plasmid family is now playing a crucial role in the global spread of diverse carbapenemase genes in Klebsiella spp.

Bench-to-bedside review: The role of beta-lactamases in antibiotic-resistant Gram-negative infections

Multidrug resistance has been increasing among Gram-negative bacteria and is strongly associated with the production of both chromosomal- and plasmid-encoded β-lactamases, whose number now exceeds 890. Many of the newer enzymes exhibit broad-spectrum hydrolytic activity against most classes of β-lactams. The most important plasmid-encoded β-lactamases include (a) AmpC cephalosporinases produced in high quantities, (b) the expanding families of extended-spectrum β-lactamases such as the CTX-M enzymes that can hydrolyze the advanced-spectrum cephalosporins and monobactams, and (c) carbapenemases from multiple molecular classes that are responsible for resistance to almost all β-lactams, including the carbapenems. Important plasmid-encoded carbapenemases include (a) the KPC β-lactamases originating in Klebsiella pneumoniae isolates and now appearing worldwide in pan-resistant Gram-negative pathogens and (b) metallo-β-lactamases that are produced in organisms with other deleterious β-lactamases, causing resistance to all β-lactams except aztreonam. β-Lactamase genes encoding these enzymes are often carried on plasmids that bear additional resistance determinants for other antibiotic classes. As a result, some infections caused by Gram-negative pathogens can now be treated with only a limited number, if any, antibiotics. Because multidrug resistance in Gram-negative bacteria is observed in both nosocomial and community isolates, eradication of these resistant strains is becoming more difficult.

Mutational analysis of VIM-2 reveals an essential determinant for metallo-beta-lactamase stability and folding

Metallo-beta-lactamase (MBL)-producing bacteria are emerging worldwide and represent a formidable threat to the efficacy of relevant beta-lactams, including carbapenems, expanded-spectrum cephalosporins, and beta-lactamase inactivator/beta-lactam combinations. VIM-2 is currently the most widespread MBL and represents a primary target for MBL inhibitor research, the clinical need for which is expected to further increase in the future. Using a saturation mutagenesis approach, we probed the importance of four residues (Phe-61, Ala-64, Tyr-67, and Trp-87) located close to the VIM-2 active site and putatively relevant to the enzyme activity based on structural knowledge of the enzyme and on structure-activity relationships of the subclass B1 MBLs. The ampicillin MIC values shown by the various mutants were affected very differently depending on the randomized amino acid position. Position 64 appeared to be rather tolerant to substitution, and kinetic studies showed that the A64W mutation did not significantly affect substrate hydrolysis or binding, representing an important difference from IMP-type enzymes. Phe-61 and Tyr-67 could be replaced with several amino acids without the ampicillin MIC being significantly affected, but in contrast, Trp-87 was found to be critical for ampicillin resistance. Further kinetic and biochemical analyses of W87A and W87F variants showed that this residue is apparently important for the structure and proper folding of the enzyme but, surprisingly, not for its catalytic activity. These data support the critical role of residue 87 in the stability and folding of VIM-2 and might have strong implications for MBL inhibitor design, as this residue would represent an ideal target for interaction with small molecules.

First survey of metallo-beta-lactamases in clinical isolates of Pseudomonas aeruginosa in a German university hospital

A total of 489 clinical isolates of Pseudomonas aeruginosa was investigated for metallo-beta-lactamase (MBL) production. Molecular analysis detected a blaVIM-1 gene in the chromosome of one isolate and a blaVIM-2 gene carried on the plasmid in seven isolates. Moreover, we showed that an initial screening by combined susceptibility testing of imipenem and ceftazidime followed by a confirmatory EDTA combination disk test represents a valid alternative to the molecular investigation of MBL genes, making MBL detection possible in routine diagnostic laboratories.

Activity of a new antipseudomonal cephalosporin, CXA-101 (FR264205), against carbapenem-resistant and multidrug-resistant Pseudomonas aeruginosa clinical strains

The activity of the new cephalosporin CXA-101 (CXA), previously designated FR264205, was evaluated against a collection of 236 carbapenem-resistant P. aeruginosa isolates, including 165 different clonal types, from a Spanish multicenter (127-hospital) study. The MICs of CXA were compared to the susceptibility results for antipseudomonal penicillins, cephalosporins, carbapenems, aminoglycosides, and fluoroquinolones. The MIC of CXA in combination with tazobactam (4 and 8 microg/ml) was determined for strains with high CXA MICs. The presence of acquired beta-lactamases was investigated by isoelectric focusing and PCR amplification followed by sequencing. Additional beta-lactamase genes were identified by cloning and sequencing. The CXA MIC50/MIC90 for the complete collection of carbapenem-resistant P. aeruginosa isolates was 1/4 microg/ml, with 95.3% of the isolates showing an MIC of <or=8 microg/ml. Cross-resistance with any of the antibiotics tested was not observed; the MIC50/MIC90 of CXA-101 was still 1/4 when multidrug-resistant (MDR) strains (42% of all tested isolates) or AmpC-hyperproducing clones (53%) were analyzed. Almost all (10/11) of the strains showing a CXA MIC of >8 microg/ml produced a horizontally acquired beta-lactamase, including the metallo-beta-lactamase (MBL) VIM-2 (one strain), the extended-spectrum beta-lactamase (ESBL) PER-1 (one strain), several extended-spectrum OXA enzymes (OXA-101 [one strain], OXA-17 [two strains], and a newly described OXA-2 derivative [W159R] designated OXA-144 [four strains]), and a new BEL variant (BEL-3) ESBL (one strain), as identified by cloning and sequencing. Synergy with tazobactam in these 11 strains was limited, although 8 microg/ml reduced the mean CXA MIC by 2-fold. CXA is highly active against carbapenem-resistant P. aeruginosa isolates, including MDR strains. Resistance was restricted to still-uncommon strains producing an acquired MBL or ESBL.

A novel tetrabranched antimicrobial peptide that neutralizes bacterial lipopolysaccharide and prevents septic shock in vivo

We describe the nonnatural antimicrobial peptide KKIRVRLSA (M33) and its capacity to neutralize LPS-induced cytokine release, preventing septic shock in animals infected with bacterial species of clinical interest. M33 showed strong resistance to proteolytic degradation when synthesized in tetrabranched form with 4 peptides linked by a lysine core, making it suitable for use in vivo. HPLC and mass spectrometry demonstrated its stability in serum beyond 24 h. M33 was found to be very selective for gram-negative bacteria. Minimal inhibitory concentration (MIC) ranged from 0.3 to 3 muM for multidrug resistant clinical isolates of several pathogenic species, including Pseudomonas aeruginosa, Klebsiella pneumoniae, and Acinetobacter baumannii. M33 neutralized LPS derived from P. aeruginosa and K. pneumoniae, and prevented TNF-alpha release from LPS-activated macrophages, with an EC(50) of 3.8e-8 M and 2.8e-7 M, respectively, as detected by sandwich ELISA. M33 activity was also tested in sepsis animal models. It averted septic shock symptoms due to Escherichia coli and P. aeruginosa in doses compatible with clinical use (5-25 mg/kg). These properties make tetrabranched M33 peptide a good candidate for the development of a new antibacterial drug.-Pini, A., Falciani, C., Mantengoli, E., Bindi, S., Brunetti, J., Iozzi, S., Rossolini, G. M., Bracci, L. A novel tetrabranched antimicrobial peptide that neutralizes bacterial lipopolysaccharide and prevents septic shock in vivo.

Dispersal of carbapenemase blaVIM-1 gene associated with different Tn402 variants, mercury transposons, and conjugative plasmids in Enterobacteriaceae and Pseudomonas aeruginosa

The emergence of bla(VIM-1) within four different genetic platforms from distinct Enterobacteriaceae and Pseudomonas aeruginosa isolates in an area with a low prevalence of metallo-beta-lactamase producers is reported. Forty-three VIM-1-producing isolates (including 19 Enterobacter cloacae, 2 Escherichia coli, and 2 P. aeruginosa isolates, 18 Klebsiella pneumoniae isolate, and 2 Klebsiella oxytoca isolate) recovered from 2005 to 2007 and corresponding to 15 pulsed-field gel electrophoresis types were studied. The Enterobacteriaceae isolates corresponded to a hospital outbreak, and the P. aeruginosa isolates were sporadically recovered. The genetic context of the integrons carrying bla(VIM-1) (arbitrarily designated types A, B, C, and D) was characterized by PCR mapping based on known Tn402 and mercury transposons and further sequencing. Among Enterobacteriaceae isolates, bla(VIM-1) was part of integrons located either in an In2-Tn402 element linked to Tn21 (type A; In110-bla(VIM-1)-aacA4-aadA1) or in a Tn402 transposon lacking the whole tni module [type B; In113-bla(VIM-1)-aacA4-dhfrII (also called dfrB1)-aadA1-catB2] and the transposon was associated with an IncHI2 or IncI1 plasmid, respectively. Among P. aeruginosa isolates, bla(VIM-1) was part of a new gene cassette array located in a defective Tn402 transposon carrying either tniBDelta3 and tniA (type C; bla(VIM-1)-aadA1) or tniC and DeltatniQ (type D; bla(VIM-1)-aadB), and both Tn402 variants were associated with conjugative plasmids of 30 kb. The dissemination of bla(VIM-1) was associated with different genetic structures and bacterial hosts, depicting a complex emergence and evolutionary network scenario in our facility, Ramón y Cajal University Hospital, Madrid, Spain. Knowledge of the complex epidemiology of bla(VIM-1) is necessary to control this emerging threat.

Infections with VIM-1 metallo-{beta}-lactamase-producing enterobacter cloacae and their correlation with clinical outcome

The aim of this study was to ascertain the incidence and clinical significance of metallo-beta-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-beta-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 bla(VIM-1) gene associated or not with a bla(SHV12) 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 bla(VIM-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.

Colonization of residents and staff of a long-term-care facility and adjacent acute-care hospital geriatric unit by multiresistant bacteria

Long-term-care facilities (LTCFs) are reservoirs of resistant bacteria. We undertook a point-prevalence survey and risk factor analysis for specific resistance types among residents and staff of a Bolzano LTCF and among geriatric unit patients in the associated acute-care hospital. Urine samples and rectal, inguinal, oropharyngeal and nasal swabs were plated on chromogenic agar; isolates were typed by pulsed-field gel electrophoresis; resistance genes and links to insertion sequences were sought by PCR; plasmids were analysed by PCR, restriction fragment length polymorphism and incompatibility grouping. Demographic data were collected. Of the LTCF residents, 74.8% were colonized with ≥1 resistant organism, 64% with extended-spectrum β-lactamase (ESBL) producers, 38.7% with methicillin-resistant Staphylococcus aureus (MRSA), 6.3% with metallo-β-lactamase (MBL) producers, and 2.7% with vancomycin-resistant enterococci. Corresponding rates for LTCF staff were 27.5%, 14.5%, 14.5%, 1.5% and 0%, respectively. Colonization frequencies for geriatric unit patients were lower than for those in the LTCF. Both clonal spread and plasmid transfer were implicated in the dissemination of MBL producers that harboured IncN plasmids bearing bla(VIM-1), qnrS, and bla(SHV-12). Most (44/45) ESBL-producing Escherichia coli isolates had bla(CTX-M) genes of group 1; a few had bla(CTX-M) genes of group 9 or bla(SHV-5); those with bla(CTX-M-15) or bla(SHV-5) were clonal. Risk factors for colonization of LTCF residents with resistant bacteria included age ≥86 years, antibiotic treatment in the previous 3 months, indwelling devices, chronic obstructive pulmonary disease, physical disability, and the particular LTCF unit; those for geriatric unit patients were age and dementia. In conclusion, ESBL-producing and MBL-producing Enterobacteriaceae and MRSA were prevalent among the LTCF residents and staff, but less so in the hospital geriatric unit. Education of LTCF employees and better infection control are proposed to minimize the spread of resistant bacteria in the facility.