Abstract: The dramatic increase in the prevalence and clinical impact of infections caused by bacteria producing carbapenemases is a global health concern. Carbapenemase production is especially problematic when encountered in members of the family Enterobacteriaceae. Due to their ability to readily spread and colonize patients in healthcare environments, preventing the transmission of these organisms is a major public health initiative and coordinated international effort are needed. Central to the treatment and control of carbapenemase-producing organisms (CPOs) are phenotypic (growth-/biochemical-dependent) and nucleic acid–based carbapenemase detection tests that identify carbapenemase activity directly or their associated molecular determinants. Importantly, bacterial isolates harboring carbapenemases are often resistant to multiple antibiotic classes, resulting in limited therapy options. Emerging agents, novel antibiotic combinations and treatment regimens offer promise for management of these infections. This review highlights our current understanding of CPOs with emphasis on their epidemiology, detection, treatment, and control.

Abstract: Klebsiella pneumoniae carbapenemase (KPC) 3–producing Escherichia coli was isolated from a carrier of KPC-3–producing K. pneumoniae. The KPC-3 plasmid was identical in isolates of both species. The patient’s gut flora contained a carbapenem-susceptible E. coli strain isogenic with the KPC-3–producing isolate, which suggests horizontal interspecies plasmid transfer.

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.

Abstract: After more than 7 decades of antibiotic use, a recurrent pattern of antimicrobial resistance spread is evident among certain bacterial pathogens. In this pattern, resistance occurs first among the most severely ill hospitalized patients, then spreads to involve other patients in the hospital, and ultimately reaches the community. These events are initially localized geographically; however, via spread from region to region, resistant bacterial strains eventually establish global endemicity. This pattern has been observed with penicillin-resistant staphylococci, methicillin-resistant Staphylococcus aureus (MRSA),1 and extended-spectrum β-lactamase (ESBL)–producing Enterobacteriaceae.2 In each case, adequate preventive measures to contain the spread of resistant pathogens were not implemented in time. In this Commentary, we discuss the implications of a new resistance threat to public health: the global spread of carbapenem-resistant Enterobacteriaceae (CRE).

Abstract: Since its discovery in England and France in 1986, vancomycin-resistant Enterococcus has increasingly become a major nosocomial pathogen worldwide. Enterococci are prolific colonizers, with tremendous genome plasticity and a propensity for persistence in hospital environments, allowing for increased transmission and the dissemination of resistance elements. Infections typically present in immunosuppressed patients who have received multiple courses of antibiotics in the past. Virulence is variable, and typical clinical manifestations include bacteremia, endocarditis, intra-abdominal and pelvic infections, urinary tract infections, skin and skin structure infections, and, rarely, central nervous system infections. As enterococci are common colonizers, careful consideration is needed before initiating targeted therapy, and source control is first priority. Current treatment options including linezolid, daptomycin, quinupristin/dalfopristin, and tigecycline have shown favorable activity against various vancomycin-resistant Enterococcus infections, but there is a lack of randomized controlled trials assessing their efficacy. Clearer distinctions in preferred therapies can be made based on adverse effects, drug interactions, and pharmacokinetic profiles. Although combination therapies and newer agents such as tedizolid, telavancin, dalbavancin, and oritavancin hold promise for the future treatment of vancomycin-resistant Enterococcus infections, further studies are needed to assess their possible clinical impact, especially in the treatment of serious infections.