Inoculated MacConkey agar culture plate cultivated colonial growth of Gram-negative, small rod-shaped and facultatively anaerobic Klebsiella pneumoniae bacteria. – CDC PHIL.
From the today’s MMWR , we’ve a report on the importation and likely nosocomial transmission of a CRE (carabapenem-resistant Enterobacteriaceae) infection containing NDM-1.
NMD-1, or New Delhi metallo-ß-lactamase-1 – is an enzyme which confers broad antibiotic resistance to various types of bacteria. Even more troubling, it rides on a plasmid (a snippet of portable DNA) that can be shared by different types of bacteria.
The good news is that NDM-1 cases in the United States are still rare enough that they merit extensive reportage in the CDC’s MMWR. The bad news is, they continue to spread around the globe and our treatment options against them are extremely limited.
A few excerpts from today’s MMWR report follow (slightly reparagraphed for readability).
June 22, 2012 / 61(24);446-448
U.S. and international efforts to control carabapenem-resistant Enterobacteriaceae (CRE) are critical to protect public health. Clinicians caring for patients infected with such organisms have few, if any, therapeutic options available. CRE containing New Delhi metallo-beta-lactamase (NDM), first reported in a patient who had been hospitalized in New Delhi, India, in 2007 (1), are of particular concern because these enzymes usually are encoded on plasmids that harbor multiple resistance determinants and are transmitted easily to other Enterobacteriaceae and other genera of bacteria (2).
A urine specimen collected on March 4, 2012, from a patient who recently had been hospitalized in Viet Nam, but who was receiving care at a hospital in Rhode Island, was found to have a Klebsiella pneumoniae isolate containing NDM.
The isolate was susceptible only to tigecycline, colistin, and polymyxin B. Point-prevalence surveys of epidemiologically linked patients revealed transmission to a second patient on the hematology/oncology unit.
These two cases bring to 13 the number of cases of NDM reported in the United States. After contact precautions were reinforced and environmental cleaning was implemented, no further cases were identified.
<SNIP Lengthy Narrative On Patients, Lab Tests, and Isolation Methods>
Erica E. Hardy, MD, Leonard A. Mermel, DO, Dept of Medicine, Kimberle C. Chapin, MD, Dept of Pathology, Warren Alpert Medical School of Brown Univ; Cindy Vanner, Rhode Island Dept of Health. Ekta Gupta, MD, Dept of Medicine, Boston Univ School of Medicine, Massachusetts. Corresponding contributor: Leonard A. Mermel, firstname.lastname@example.org, 401-444-2608.
Since the first report in 2009, cases involving NDM-producing Enterobacteriaceae have been reported in every continent except South America and Antarctica (7). Among 29 cases in the United Kingdom, at least 17 involved patients who had traveled to India or Pakistan, among whom 14 had been hospitalized in one of those countries (8).
Although medical care in the Indian subcontinent was associated with many early reports, recent cases have been described involving persons who traveled to endemic regions* but were not hospitalized (7). The plasmid-carrying NDM is highly transmissible to other bacteria, and bacteria carrying NDM can colonize the gastrointestinal systems of humans for prolonged periods and can spread through contamination of water sources and environmental surfaces (7).
Not surprisingly, nosocomial spread also has been documented outside of the Indian subcontinent. Of 77 cases of infection or colonization with CRE containing NDM in Europe, 13 might have been hospital-acquired in Europe (9). Spread of NDM in other parts of Asia also has been reported, including four patients in South Korea without travel history (10), similar to recent reports elsewhere (7).
In summary, the report offers the following:
What is already known on this topic?
New Delhi metallo-beta-lactamase (NDM)–producing Klebsiella pneumoniae are resistant to extended-spectrum antimicrobials, including carbapenems. The resistance mechanism is highly transmissible and its presence substantially limits treatment options. NDM-producing Enterobacteriaceae have been identified in the United States, primarily among patients with exposure to health care in endemic countries.
What is added by this report?
An NDM-producing organism was isolated from a patient being treated in the United States after having been hospitalized in Vietnam. Implementation of CDC-recommended carbapenem-resistant Enterobacteriaceae (CRE) control practices, including surveillance cultures of epidemiologically linked contacts, identified likely transmission to one other patient on the same ward of the U.S. hospital. Additional control measures were applied and additional surveillance and clinical cultures have not identified further transmission.
What are the implications for public health practice?
An aggressive approach to control of CRE, including highly transmissible carbapenemase-producing organisms, is essential to slow the spread of these organisms in the United States. In an outbreak, use of surveillance cultures to identify asymptomatic transmission potentially is an important part of these efforts.
Without a doubt the `go to’ blogger on all things antibiotic resistant is Maryn McKenna, author of Superbug: The Fatal Menace of MRSA. If you aren’t a regular visitor to her Superbug Blog, you should be.
One where even common infections may become untreatable.
While we aren’t there yet, reports such as this one add to the growing concern that someday, that fear may become a reality.