Clinical Pharmacist and Master’s student in Clinical Pharmacy with research interests in pharmacovigilance, behavioral interventions in mental health, and AI applications in clinical decision support. Experience includes digital health research with Bloomsbury Health (London) and pharmacovigilance practice in patient support programs. Published work covers drug awareness among healthcare providers, postpartum depression management, and patient safety reporting. 
Clinical Pharmacist and Master’s student in Clinical Pharmacy with research interests in pharmacovigilance, behavioral interventions in mental health, and AI applications in clinical decision support. Experience includes digital health research with Bloomsbury Health (London) and pharmacovigilance practice in patient support programs. Published work covers drug awareness among healthcare providers, postpartum depression management, and patient safety reporting. What was reviewed?
This review article titled “Heavy Metal Toxicity in Armed Conflicts Potentiates AMR in A. baumannii by Selecting for Antibiotic and Heavy Metal Co-resistance Mechanisms,” provides a comprehensive synthesis of evidence linking heavy metal contamination from warfare to the emergence of antimicrobial resistance (AMR) in Acinetobacter baumannii. The review critically examines the role of heavy metals—such as copper, mercury, arsenic, chromium, and lead commonly found in military ordnance and environmental debris in conflict zones, in promoting bacterial resistance not only to metals but also to antibiotics. The article explains the various molecular and genetic mechanisms by which bacteria, especially A. baumannii, acquire resistance to heavy metals and how these mechanisms are often co-located with antibiotic resistance genes on mobile genetic elements.
Who was reviewed?
The review synthesizes data and findings from a broad spectrum of studies involving bacterial populations, with a special focus on Acinetobacter baumannii isolated from war zones such as Lebanon, Iraq, Syria, and Afghanistan. The reviewed literature encompasses both environmental isolates (from soil, water, and debris contaminated by military activities) and clinical isolates from wounded soldiers and civilians treated in hospitals. The review also draws on studies of other bacteria (such as E. coli, Pseudomonas spp., Enterococcus faecium, and Salmonella typhi) to illustrate generalizable mechanisms of heavy metal and antibiotic co-resistance. The populations reviewed include microbial communities inhabiting environments with high heavy metal loads due to warfare and military-related pollution, as well as bacteria from clinical infections, particularly those associated with trauma and war wounds.
Most Important Findings
| Critical Points | Details |
|---|---|
| Heavy metals prevalent in warfare environments | Copper, mercury, arsenic, chromium, and lead are extensively used in military ordnance and contaminate war zones, contributing to environmental selection pressures. |
| Bacterial resistance mechanisms | Bacteria utilize efflux pumps, intracellular and extracellular sequestration, enzymatic detoxification, and target modification to resist heavy metals. Many of these mechanisms are encoded on mobile genetic elements. |
| Co-localization of resistance genes | Genes conferring resistance to both heavy metals and antibiotics are often physically linked on plasmids, transposons, or genomic islands, enabling co-selection under heavy metal exposure. |
| Co-selection pathways | Heavy metals drive AMR via co-resistance (linked genes), cross-resistance (shared efflux systems), and co-regulation (mutual regulatory proteins controlling both resistance types). |
| A. baumannii as a model organism | This species, prominent in war wounds, possesses multiple heavy metal resistance determinants, suggesting a strong capacity for acquiring and disseminating multidrug resistance under environmental stress. |
| Whole-genome sequencing utility | WGS is highlighted as an effective tool for identifying resistance determinants, monitoring the spread of co-resistance, and informing surveillance efforts. |
| Implications for AMR beyond antibiotics | The review makes clear that AMR can evolve and spread in the absence of antibiotic use, simply through environmental heavy metal contamination, challenging current stewardship paradigms. |
Key Implications
For heavy metal certification programs, this review underscores the urgent need to monitor and regulate heavy metal contamination, as environmental exposure alone can drive antibiotic resistance. Certification must address not only direct toxicity but also the potential for heavy metals to select for multidrug-resistant bacteria, especially in high-risk areas.
Citation
Bazzi W, Abou Fayad AG, Nasser A, Haraoui L-P, Dewachi O, Abou-Sitta G, Nguyen V-K, Abara A, Karah N, Landecker H, Knapp C, McEvoy MM, Zaman MH, Higgins PG, Matar GM. Heavy Metal Toxicity in Armed Conflicts Potentiates AMR in A. baumannii by Selecting for Antibiotic and Heavy Metal Co-resistance Mechanisms. Front Microbiol. 2020;11:68. doi:10.3389/fmicb.2020.00068
Heavy metals are high-density elements that accumulate in the body and environment, disrupting biological processes. Lead, cadmium, arsenic, mercury, nickel, tin, aluminum, and chromium are of greatest concern due to persistence, bioaccumulation, and health risks, making them central to the HMTC program’s safety standards.
Mercury (Hg) is a neurotoxic heavy metal found in various consumer products and environmental sources, making it a major public health concern. Its regulation is critical to protect vulnerable populations from long-term health effects, such as neurological impairment and cardiovascular disease. The HMTC program ensures that products meet the highest standards for mercury safety.
Arsenic is a naturally occurring metalloid that ranks first on the ATSDR toxic substances list. Inorganic arsenic contaminates water, rice and consumer products, and exposure is linked to cardiovascular disease, cognitive deficits, low birth weight and cancer. HMTC’s stringent certification applies ALARA principles to protect vulnerable populations.
Lead is a neurotoxic heavy metal with no safe exposure level. It contaminates food, consumer goods and drinking water, causing cognitive deficits, birth defects and cardiovascular disease. HMTC’s rigorous lead testing applies ALARA principles to protect infants and consumers and to prepare brands for tightening regulations.
