Azita Leavitt

Predictors of Carbapenem-Resistant Klebsiella pneumoniae Acquisition among Hospitalized Adults and Effect of Acquisition on Mortality

ABSTRACT Carbapenem-resistant Klebsiella pneumoniae (CRKP) is an emerging nosocomial pathogen. Little is known about its risk factors or mortality. We performed a case-case-control study to assess the risks for CRKP isolation and a retrospective cohort study to assess mortality in three groups of hospitalized adults: (i) patients from whom CRKP was isolated, (ii) patients from whom carbapenem-susceptible Klebsiella spp. (CSKS) were isolated, and (iii) controls from whom no Klebsiella spp. were isolated. After adjustment for length of stay (LOS), the demographics, comorbidities, and exposures of each case group were compared with those of the controls. Significant covariates were incorporated into LOS-adjusted multivariable models. In the mortality study, we evaluated the effect of CRKP on in-hospital death. There were 48 patients with CRKP isolation (21 died [44%]), 56 patients with CSKS isolation (7 died [12.5%]), and 59 controls (1 died [2%]). Independent risk factors for CRKP isolation were poor functional status (odds ratio [OR], 15.4; 95% confidence interval [CI], 4.0 to 58.6; P < 0.001); intensive care unit (ICU) stay (OR, 17.4; 95% CI, 1.5 to 201.9; P = 0.02); and receipt of antibiotics (OR, 4.4; 95% CI, 1.0 to 19.2; P = 0.05), particularly fluoroquinolones (OR, 7.2; 95% CI, 1.1 to 49.4; P = 0.04). CRKP was independently associated with death when patients with CRKP were compared with patients with CSKS (OR, 5.4; 95% CI, 1.7 to 17.1; P = 0.005) and with controls (OR, 6.7; 95% CI, 2.4 to 18.8; P < 0.001). After adjustment for the severity of illness, CRKP isolation remained predictive of death, albeit with a lower OR (for the CRKP group versus the CSKS group, OR, 3.9; 95% CI, 1.1 to 13.6; and P = 0.03; for the CRKP group versus the controls, OR, 5.0; 95% CI, 1.7 to 14.8; and P = 0.004). CRKP affects patients with poor functional status, an ICU stay, and antibiotic exposure and is an independent predictor of death.

Influx of Extended-Spectrum β-Lactamase—Producing Enterobacteriaceae into the Hospital

BACKGROUND The prevalence of infections caused by extended-spectrum beta -lactamase (ESBL)-producing Enterobacteriaceae is increasing worldwide. The influx of these bacteria into hospitals has major implications for infection-control and empirical treatment strategies. METHODS Isolates from 2 patient cohorts--patients with gram-negative bacteremia within 2 days after admission and patients screened for fecal colonization at admission--were assessed for ESBL production. ESBL phenotype was confirmed according to Clinical and Laboratory Standards Institute guidelines. Predictors of ESBL phenotype were examined by univariate and multivariate analyses. RESULTS Of 80 Enterobacteriaceae isolates from blood samples obtained at admission to the hospital, 13.7% produced ESBL. Thirty-eight patients with ESBL-positive isolates and 72 with ESBL-negative isolates were included in a case-control study. Predictors of ESBL production were male sex and nursing home residence (area under receiver operator characteristic curve, 0.7). Of 241 persons screened at admission, 26 (10.8%) had fecal carriage of ESBL-producing Enterobacteriaceae. Predictors of fecal carriage were poor functional status, antibiotic use, chronic renal insufficiency, liver disease, and use of histamine2 blockers (area under receiver operator characteristic curve, 0.8). Four (15.4%) of the 26 individuals with fecal carriage had subsequent bacteremia with ceftazidime-resistant Enterobacteriaceae, compared with 1 (0.5%) noncarrier (odds ratio, 38.9; P<.001). Of 80 ESBL-producing Enterobacteriaceae isolates obtained at admission, 65 were health care associated, and 15 were community acquired. The 15 community-acquired ESBL-producing Enterobacteriaceae belonged to diverse clones. The most prevalent ESBL gene among these isolates was CTX-M-2 (found in 53.3% of the isolates). CONCLUSIONS We report high rates of bacteremia and colonization with ESBL-producing Enterobacteriaceae at admission to our institution, which may undermine infection-control measures and complicate the selection of empirical treatment.

Emergence of KPC-2 and KPC-3 in Carbapenem-Resistant Klebsiella pneumoniae Strains in an Israeli Hospital

ABSTRACT Carbapenem resistance due to KPC has rarely been observed outside the United States. We noticed a sharp increase in carbapenem-resistant Klebsiella pneumoniae strains possessing KPC in Tel Aviv Medical Center from 2004 to 2006. Sixty percent of the isolates belonged to a single clone susceptible only to gentamicin and colistin and carried the blaKPC-3 gene, while almost all other clones carried the blaKPC-2 gene. This rapid dissemination of KPC outside the United States is worrisome.

First Report on a Hyperepidemic Clone of KPC-3-Producing Klebsiella pneumoniae in Israel Genetically Related to a Strain Causing Outbreaks in the United States

ABSTRACT A highly epidemic carbapenem-resistant clone of KPC-3-producing Klebsiella pneumoniae emerged in Israel in 2006, causing a nationwide outbreak. This clone was genetically related to outbreak strains from the United States isolated in 2000 but differed in KPC-carrying plasmids. The threat of the global spread of hyperepidemic, extensively drug-resistant bacterial strains should be recognized and confronted.

Plasmid-Mediated Imipenem-Hydrolyzing Enzyme KPC-2 among Multiple Carbapenem-Resistant Escherichia coli Clones in Israel

ABSTRACT Carbapenem resistance in Escherichia coli is rare. We report four genetically unrelated carbapenem-resistant E. coli isolates cultured from four patients hospitalized in Tel Aviv Medical Center. PCR, sequencing, and Southern blot analysis identified KPC-2 as the imipenem-hydrolyzing enzyme in all four strains, carried on different plasmids with a possible common origin. This is the first discovery of KPC-2 in E. coli and the first report of this enzyme originating outside the United States.

Methicillin-resistant Staphylococcus aureus in Neonatal Intensive Care Unit

A neonatal intensive care unit outbreak was caused by a strain of methicillin-resistant Staphylococcus aureus previously found in the community (ST45-MRSA-IV). Fifteen infected neonates were identified, 2 of whom died. This outbreak illustrates how a rare community pathogen can rapidly spread through nosocomial transmission.

Molecular epidemiology, sequence types, and plasmid analyses of KPC-producing Klebsiella pneumoniae strains in Israel.

ABSTRACT Sporadic isolates of carbapenem-resistant KPC-2-producing Klebsiella pneumoniae were isolated in Tel Aviv Medical Center during 2005 and 2006, parallel to the emergence of the KPC-3-producing K. pneumoniae sequence type 258 (ST 258). We aimed to study the molecular epidemiology of these isolates and to characterize their blaKPC-carrying plasmids and their origin. Ten isolates (8 KPC-2 and 2 KPC-3 producing) were studied. All isolates were extremely drug resistant. They possessed the blaKPC gene and varied in their additional beta-lactamase contents. The KPC-2-producing strains belonged to three different sequence types: ST 340 (n = 2), ST 277 (n = 2), and a novel sequence type, ST 376 (n = 4). Among KPC-3-producing strains, a single isolate (ST 327) different from ST 258 was identified, but both strains carried the same plasmid (pKpQIL). The KPC-2-encoding plasmids varied in size (45 to 95 kb) and differed among each of the STs. Two of the Klebsiella blaKPC-2-carrying plasmids were identical to plasmids from Escherichia coli, suggesting a common origin of these plasmids. These data indicate that KPC evolution in K. pneumoniae is related to rare events of interspecies spread of blaKPC-2-carrying plasmids from E. coli followed by limited clonal spread, whereas KPC-3 carriage in this species is related almost strictly to clonal expansion of ST 258 carrying pKpQIL.

Complete Nucleotide Sequence of KPC-3-Encoding Plasmid pKpQIL in the Epidemic Klebsiella pneumoniae Sequence Type 258

ABSTRACT We have determined the entire DNA sequence of plasmid pKpQIL, the blaKPC-3-carrying plasmid harbored by the carbapenem-resistant Klebsiella pneumoniae clone sequence type 258 (ST 258) in Israel. pKpQIL is a 113,637-bp, self-transmissible plasmid that belongs to the incompatibility group IncFII. It consists of a large backbone of a pKPN4-like plasmid and carries the blaKPC-3-containing Tn4401a transposon of a pNYC-like plasmid.

Plasmid pKpQIL encoding KPC-3 and TEM-1 confers carbapenem resistance in an extremely drug-resistant epidemic Klebsiella pneumoniae strain

OBJECTIVES An extremely drug-resistant (XDR) clone of KPC-3-producing Klebsiella pneumoniae emerged in Israel in 2006, causing a nationwide outbreak. We aimed to characterize the local KPC-3-encoding plasmid carried by these isolates and study its contribution to antibiotic resistance. METHODS Mechanisms of carbapenem resistance were investigated in seven selected isolates (isolated between 2006 and 2008) belonging to the epidemic clone. Isolates underwent MIC testing, and were examined for the presence of KPC, Tn4401, class I integron elements and additional antibiotic resistance genes. Plasmids were analysed by transformation, transconjugation, restriction mapping, curing and complementation experiments. Outer membrane protein (OMP) analysis was performed. RESULTS OMP analysis did not reveal loss of porins. KPC-3-producing K. pneumoniae isolates possessed various plasmids but all harboured a common self-transmissible 105 kb plasmid, termed pKpQIL, encoding bla(TEM-1) and bla(KPC-3). Curing of pKpQIL led to a complete loss of resistance to cephalosporins and carbapenems, proving its crucial role in carbapenem resistance. Transformation of plasmid pKpQIL into the cured Klebsiella strain resulted in full reconstitution of carbapenem resistance. The presence of all Tn4401 transposon elements located upstream of the KPC-3 gene was detected by PCR and sequencing. pKpQIL lacked additional antibiotic resistance genes. CONCLUSIONS Our findings demonstrate the presence of pKpQIL, a 105 kb KPC-3- and TEM-1-encoding plasmid, in the XDR K. pneumoniae epidemic strain in Israel. pKpQIL is unique and appears consistently in all isolates of this clone over the years. The extensive beta-lactam resistance phenotype of this clone is primarily mediated by this single self-transmissible plasmid.

Extended-Spectrum Beta-Lactamases among Enterobacter Isolates Obtained in Tel Aviv, Israel

ABSTRACT The extended-spectrum beta-lactamase (ESBL)-producing phenotype is frequent among Enterobacter isolates at the Tel Aviv Sourasky Medical Center, Tel Aviv, Israel. We examined the clonal relatedness and characterized the ESBLs of a collection of these strains. Clonal relatedness was determined by pulsed-field gel electrophoresis. Isoelectric focusing (IEF) and transconjugation experiments were performed. ESBL gene families were screened by colony hybridization and PCR for blaTEM, blaSHV, blaCTX-M, blaIBC, blaPER, blaOXA, blaVEB, and blaSFO; and the PCR products were sequenced. The 17 Enterobacter isolates studied comprised 15 distinct genotypes. All isolates showed at least one IEF band (range, one to five bands) whose appearance was suppressed by addition of clavulanate; pIs ranged from 5.4 to ≥8.2. Colony hybridization identified at least one family of beta-lactamase genes in 11 isolates: 10 harbored blaTEM and 9 harbored blaSHV. PCR screening and sequence analysis of the PCR products for blaTEM, blaSHV, and blaCTX-M identified TEM-1 in 11 isolates, SHV-12 in 7 isolates, SHV-1 in 1 isolate, a CTX-M-2-like gene in 2 isolates, and CTX-M-26 in 1 isolate. In transconjugation experiments with four isolates harboring blaTEM-1 and blaSHV-12, both genes were simultaneously transferred to the recipient strain Escherichia coli HB101. Plasmid mapping, PCR, and Southern analysis with TEM- and SHV-specific probes demonstrated that a single transferred plasmid carried both the TEM-1 and the SHV-12 genes. The widespread presence of ESBLs among Enterobacter isolates in Tel Aviv is likely due not to clonal spread but, rather, to plasmid-mediated transfer, at times simultaneously, of genes encoding several types of enzymes. The dominant ESBL identified was SHV-12.