Tracking MDROs, Acinetobacter in U.S. Military Personnel

William G Meyer, of the Armed Forces Health Surveillance Center in Silver Spring, Md., and colleagues, report in BMC Public Health on the international infectious disease surveillance that has been conducted by the U.S. Department of Defense (DoD) that has been consolidated within the Armed Forces Health Surveillance Center, Division of Global Emerging Infections Surveillance and Response System (AFHSC-GEIS), including activities that monitor the presence of antimicrobial resistance among pathogens.

AFHSC-GEIS partners work within DoD military treatment facilities and collaborate with host-nation civilian and military clinics, hospitals and university systems. The goals of these activities are to foster military force health protection and medical diplomacy. Surveillance activities include both community-acquired and healthcare-associated infections and have promoted the development of surveillance networks, centers of excellence and referral laboratories. Information technology applications have been utilized increasingly to aid in DoD-wide global surveillance for diseases significant to force health protection and global public health.

One of the activities of the network achieved through AFHSC-GEIS partners has been surveillance of HAIs and multidrug-resistant organisms (MDROs). As Meyer, et al. write, "Healthcare-associated infections and antimicrobial resistance have emerged as important public health problems in both developed and resource-poor countries, as well as among U.S. Department of Defense personnel. Increased surveillance in hospitals in developing countries may determine risk factors (e.g., overuse of antibiotics, counterfeit drugs or deficiencies in local patient management guidelines and policies) that are different from those in developed countries. This may also define high-risk medical practices and enable the hospitals to tailor and implement intervention plans to reduce infection rates in resource-limited settings. These surveillance activities may become examples that other developing countries can follow in their attempts to reduce nosocomial infection rates and increase the safety of health care systems in regions where U.S. personnel and travelers visit frequently. Furthermore, knowledge about the genetic determinants of antimicrobial resistance can be very important for tailoring antibiotic policies and tracing the nosocomial spread of pathogens. Molecular characterization studies are essential tools that may help reduce nosocomial infection mortality rates and the cost of treating antibiotic-resistant infections, and limit inappropriate antibiotic use."

The researchers report that 30,000-plus U.S. military personnel have been wounded in action while serving in Iraq or Afghanistan, and many of these patients are at risk for serious complications. They write, "Wound infections have been a common complication of these injuries and, as in previous wars, are often caused by Gram-negative organisms. Minimal information is available about the mechanism of antimicrobial resistance of bacterial infections in Middle Eastern countries. Working with various regional host-nation partners, the laboratories have been able to document the geographic spread of antimicrobial resistance in common organisms. This vital information is used to effectively advise local and national healthcare leaders about necessary changes to antimicrobial formularies and provides important information on appropriate antibiotic treatment for troops deployed in the Middle East. Extended spectrum beta-lactamase-producing gram-negative rods and Acinetobacter baumannii are major causes of infections in healthcare settings. Many of these nosocomial infections are difficult to treat with antibiotics, and the antibiotic-resistant organisms that cause them are increasingly being seen in community-acquired infections."

Meyer, et al. continue, "The NAMRU-3 surveillance of healthcare-acquired infections and antimicrobial resistance demonstrated that Gram-negative organisms constituted the majority of isolates in both countries (61 percent in Egypt and 65.2 percent in Jordan). In Jordan, Klebsiella species were the most commonly isolated Gram-negative pathogens (17.4 percent of all isolates), whereas in Egypt, Klebsiella species and A. baumannii were equally prevalent among the Gram-negative bacilli with each organism accounting for 15.4 percent of the isolates. Not surprisingly, high rates of antimicrobial resistance were reported in hospitals in both countries. Extended-spectrum beta-lactamase producer rates among E. coli isolates were 64.3 and 66.7 percent in Egypt and Jordan, respectively. Klebsiella species showed extended-spectrum beta-lactamase producer rates of 57.1 percent in Egypt and 75 percent in Jordan. In Egypt, resistance of Pseudomonas aeruginosa to imipenem was 58.8 percent, and almost 88 percent of Staphylococcus aureus isolates were resistant to methicillin. The higher rates of antimicrobial resistance in specific intensive-care units (ICUs) encourage the establishment of better-informed antimicrobial use policies and implementation of stricter infection control practices. These mitigations help decrease antimicrobial resistance rates and reduce the risk of spread to the community."

The researchers emphasize that antimicrobial-resistant strains of bacteria threaten U.S. military personnel deployed in the Middle East and Afghanistan from combat- and non-combat-related infections caused by these highly resistant pathogens: "Acinetobacter baumannii-calcoaceticus complex, P. aeruginosa, Klebsiella and E. coli are common pathogens, but, compared to past wars, the acquisition of multidrug-resistant isolates appears to be significantly increased [11]. A. baumannii is a common nosocomial challenge in Egypt and has emerged as one of the important opportunistic pathogens in hospitalized patients throughout the world. Additionally, these infections plague DoD and Veterans Affairs medical treatment facilities and contribute to prolonged hospital stays. Outbreaks of Acinetobacter infections are becoming increasingly common among patients in ICUs, surgical units and burn units. The severe impact of an Acinetobacter outbreak on hospital operations requires a quick assessment of the potential spread of these infections. Comparison of A. baumannii PFGE patterns from Egypt with isolates collected at military treatment facilities in the U.S. showed high levels of genetic variability among collections. The majority of the Acinetobacter isolates cultured from hospitalized injured personnel have been multidrug-resistant, limiting the use of some empiric antibiotics for treatment of wound infections. Continuous surveillance with genetic characterization of Acinetobacter is the ideal method to direct infection-control measures or altering of antimicrobial regimens. Molecular genotyping of these isolates enhances infection control of personnel wounded in the Middle East and the possible nosocomial transmission of these organisms within the DoD hospital system. Characterization of the multi-drug resistant organisms via PFGE genotyping will help identify possible sources of infection and lead to strategies for employing appropriate antibiotics and isolation practices."

Reference: Meyer WG, Pavlin JA, and Hospenthal D, et al. Antimicrobial resistance surveillance in the AFHSC-GEIS network. BMC Public Health 2011, 11(Suppl 2):S8doi:10.1186/1471-2458-11-S2-S8.