Inoculated MacConkey agar culture plate cultivated colonial growth of Gram-negative, small rod-shaped and facultatively anaerobic Klebsiella pneumoniae bacteria. – CDC PHIL.
# 6440
In a study reminiscent of one we saw published in April of last year (see Lancet Study: NDM-1 In New Delhi Water Supply), the CDC’s EID Journal has a letter by R. Isozumi et al. that appears (ahead of print) in their August issue, that reveals the detection of the NDM-1 gene in a river in Hanoi.
blaNDM-1–positive Klebsiella pneumoniae from Environment, Vietnam
Rie Isozumi , Kumiko Yoshimatsu, Tetsu Yamashiro, Futoshi Hasebe, Binh Minh Nguyen, Tuan Cuong Ngo, Shumpei P. Yasuda, Takaaki Koma, Kenta Shimizu, and Jiro Arikawa
By way of explanation, blaNDM-1 is the gene responsible for creating the NDM-1 (New Delhi metallo-β-lactamase) enzyme that can make many types of bacteria resistant to a wide spectrum of antibiotics.
Of particular concern, this enzyme is carried by a plasmid – a snippet of portable DNA - that can be transferred to other types of bacteria (see Study: Adaptation Of Plasmids To New Bacterial Species).
Over the past few years we have seen a worrisome expansion of β-lactamase enzymes in bacteria, and they are slowly eroding the value of much of our antibiotic arsenal.
Those that inhibit the antimicrobial actions of the (formerly resistant) Carbapenem class of antibiotics – called carbapenemases – are of particular concern. Carbapenems are often used as the drug of last resort for treating difficult bacterial infections, including Escherichia coli (E. coli) and Klebsiella pneumoniae.
So when the gene responsible for the NDM-1 enzyme begins to show up in the environment, doctors and researchers take notice.
The author’s of today’s EID Journal report state their reasons for concern:
The possible appearance of bacteria harboring blaNDM-1 in Vietnam is of concern because cultural and economic links between Vietnam and India are strongly established, including extensive person-to-person exchanges that could enable easy exchange of pathogens. In addition, Vietnam faces a serious problem of antimicrobial drug resistance because drugs are freely available and used in an indiscriminate fashion. Thus, once blaNDM-1–positive bacteria colonize persons in Vietnam, they would be able to spread easily and pose a serious public health threat.
To look for environmental blaNDM-1, researchers examined water samples taken from 20 locations within 10 km of Hanoi, Vietnam. Samples were collected from rivers, lakes, and standing water in the streets.
The authors report finding the NDM-1 enzyme producing gene in two locations – 3km apart – in the Kim Nguu River, which flows through the city. They write:
We harvested several species of bacteria from the 2 seepage samples positive for blaNDM-1: Acinetobacter baumannii, Klebsiella pneumoniae, Pseudomonas aeruginosa, P. fluorescens/putida, and P. luteola.
They also report finding 2 other βeta-lactamases (blaTEM-1 and blaCTX-M-3) that were highly resistant to another class of antibiotics called aminoglycosides (which include neomycin, streptomycin & tobramycin)
The authors conclude by saying:
Wide-scale surveillance of environmental and clinical samples in Vietnam and establishment of a strategy to prevent further spread of blaNDM-1 are urgently needed.
It’s been nearly 2 years since The Lancet published a study (see NDM-1: A New Acronym To Memorize) by Walsh, Toleman, Livermore, et al. that awakened the world to the emergence and growing prevalence of the NDM-1 enzyme.
Since that time, we’ve seen a slow, but inexorable spread of NDM-1 carrying bacteria around the globe. A few of my past blogs on the subject include:
WHO Unveils 6-Point Plan To Preserve Antibiotic Effectiveness
Eurosurveillance On Antimicrobial Resistance
For a far more complete discussion of antimicrobial resistance issues, I can think of no better primer than Maryn McKenna’s book SUPERBUG: The Fatal Menace of MRSA. And Maryn’s SUPERBUG Blog, part of Wired Science Blogs, continues to provide the best day-to-day coverage of these issues.
Last March, Director-General of the World Health Organization Margaret Chan warned that the World Faces A `Post-Antibiotic Era’. One where even common infections may become untreatable.
While we aren’t there yet, reports such as the one today in the EID Journal add to the growing concern that someday, that fear may become a reality.
