Identification of extended-spectrum-ß-lactamase-positive Klebsiella pneumoniae urinary tract isolates harboring KPC and CTX-M ß-lactamases in nonhospitalized patients.

Forty-seven extended-spectrum-ß-lactamase-positive Klebsiella pneumoniae urinary tract isolates from nonhospitalized patients were identified, and 79% harbored KPC and/or CTX-M ß-lactamases. Approximately 90% of the isolates were resistant to trimethoprim-sulfamethoxazole and levofloxacin, and 40% were resistant to a carbapenem, while 92% were susceptible to polymyxin B, 87% were susceptible to tigecycline, and 79% were susceptible to fosfomycin. Increased use of broader-spectrum antibiotics may help to prevent their dissemination and reduce the risk of progression to invasive disease.

Identification of CTX-M ß-lactamases among Escherichia coli from the community in New York City.

We have identified CTX-M group 1 ß-lactamases in 87% of community-acquired Escherichia coli isolates that produce extended-spectrum ß-lactamases, with the majority harboring CTX-M-15 and representing the ST131 clonal group. Seventy percent of CTX-M-bearing isolates were from urine specimens; a large proportion was nonsusceptible to levofloxacin, trimethoprim/sulfamethoxazole, and ß-lactam antimicrobials. Many patients were relatively youthful (41% ≤65 years old; youngest, age 32). Patients with symptomatic bacteriuria received drugs to which the organisms were susceptible, and most had favorable outcomes. Timely recognition of such isolates could help physicians choose more appropriate antibacterial therapy.

Phenotypic and genotypic screening and clonal analysis of carbapenem-resistant Klebsiella pneumoniae at a single hospital.

Detection of bla(KPC)-harboring Klebsiella pneumoniae (KP) in the clinical laboratory remains a difficult task. Decreased ertapenem (ERT) susceptibility has been considered one of the most sensitive phenotypic indicators of K. pneumoniae carbapenemase (KPC) production, but has been found to be nonspecific. Susceptibility testing using imipenem or meropenem lacks the sensitivity for detection of KPCs, and there is limited experience using doripenem (DOR). Fifty-five individual ERT-nonsusceptible KP isolates and 19 isolates that were ERT-susceptible, extended spectrum ß-lactamase-positive KP were collected from the clinical laboratory and tested for DOR susceptibility by Etest methodology. PCR screening for bla(KPC) was performed on all specimens. All but three isolates with ERT resistance were KPC positive by PCR. Compared to PCR, ERT detection of KPC had a sensitivity of 98% and a false-positive rate of 6%. Overall, there was a 97% agreement between ERT and DOR susceptibility results. However, there was one KPC-positive isolate that was discrepant (ERT susceptible, DOR nonsusceptible by Etest). Selected isolates of KP from both groups underwent pulsed-field gel electrophoresis analysis to determine the degree of genetic relatedness of KPC-positive and KPC-negative isolates. Pulsed-field gel electrophoresis of selected KPC-positive and KPC-negative KP identified a common pattern between both groups. The resistance to DOR and/or ERT is sensitive and a specific indicator for detection of bla(KPC) in KP.

Polymyxin-resistant clinical isolates of Escherichia coli.

A surveillance study to identify patients from the community with Escherichia coli resistant to broad-spectrum cephalosporins discovered two isolates that were also resistant to polymyxin B and colistin. One isolate from a patient in the community and a second from a patient who received multiple courses of polymyxin B also possessed a CTX-M-15 enzyme. Resistance to cationic peptides in E. coli is unusual, and testing for susceptibility to these agents should be performed.

Identification of CTX-M beta-lactamases in Escherichia coli from hospitalized patients and residents of long-term care facilities.

Bacteria harboring CTX-M extended-spectrum beta-lactamases (ESBLs) have been identified worldwide, with most reports coming from regions outside North America. We have identified CTX-M enzymes in 31% of ESBL-positive Escherichia coli isolates from our hospital and more than half (53%) of the isolates from associated long-term care facilities. Approximately 3/4 of all CTX-M-bearing isolates were from urine specimens, with a predominance of CTX-M-15. A large proportion of such isolates were nonsusceptible to levofloxacin, trimethoprim/sulfamethoxazole, and all beta-lactam antimicrobials with the exception of the carbapenems, requiring carbapenem therapy for acute urinary tract infection or urinary tract-related sepsis. CTX-M beta-lactamases have emerged within our location, and detection of bacteria harboring these enzymes in the clinical microbiology laboratory remains problematic because molecular methods are needed for their identification.

Carbapenem-resistant Escherichia coli harboring Klebsiella pneumoniae carbapenemase beta-lactamases associated with long-term care facilities.

Nine carbapenem-resistant Escherichia coli isolates harboring Klebsiella pneumoniae carbapenemase (KPC)-2 or KPC-3 enzymes were identified in patients residing in 7 distinct long-term care facilities. Cefotaxime-hydrolyzing (CTX-M)-type beta-lactamases were also documented in 3 isolates. The identification of these enzymes in patients staying in long-term care facilities should be of great concern to all components of health care systems.

Identification of carbapenem-resistant klebsiella pneumoniae harboring KPC enzymes in New Jersey.

Klebsiella pneumoniae isolates harboring KPC enzymes have been identified in many geographical areas since 2001. Numerous problems exist in the detection and treatment of patients with such isolates. The clinical characteristics and molecular epidemiology associated with 12 randomly chosen patients in whom these enzymes were detected by molecular methods are described. This is the first description of the identification of carbapenem-resistant K. pneumoniae isolates harboring KPC beta-lactamases at the Veterans Administration Hospital in New Jersey (VA NJHCS). Because recognition of carbapenem resistance in K. pneumoniae due to KPC enzymes can only be achieved by molecular methods, detection in the Clinical Microbiology Laboratory by routine methods will continue to be difficult, leading to dilemmas in treatment.