High Burden of Multidrug Resistance and β-Lactamase-Associated Resistance Phenotypes among Gram-Negative Bacilli in Regional Healthcare Facilities in Northern Tanzania

In the microscopic world that lives inside and around us, bacteria are constantly evolving. Some of these tiny organisms have developed a way to survive the medicines doctors use to kill them, a phenomenon known as antimicrobial resistance. When a bacterium becomes resistant, the standard drugs no longer work, leaving infections harder to treat and sometimes leading to longer hospital stays or even death. This is especially true for a group of bacteria called Gram-negative bacilli, which are shaped like rods and include common culprits like E. coli and Klebsiella pneumoniae. These germs can cause serious infections in the blood, urine, and lungs. A major concern for doctors is that these bacteria often produce special enzymes, which are tiny biological tools that act like scissors, cutting apart antibiotics and rendering them useless before they can do their job. When a single bacterium becomes resistant to many different types of antibiotics at once, it is called multidrug-resistant, and if it resists almost everything available, it is termed extensively drug-resistant. Understanding how widespread these resistant bacteria are in specific communities is vital, because without this knowledge, doctors cannot choose the right medicine to save a patient's life.

In a recent study, researchers set out to map this invisible threat in the Manyara Region of northern Tanzania, an area where detailed data on bacterial resistance was previously scarce. They focused their investigation on two healthcare facilities: the Manyara Regional Referral Hospital and the Haydom Lutheran Hospital. Over a period spanning from late 2025 to mid-2026, the team collected and analyzed 370 unique samples of Gram-negative bacteria taken from patients. These samples came from various sources, including pus from wounds, urine, and blood, representing a cross-section of patients from outpatient clinics and hospital wards. The researchers identified the specific type of bacteria in each sample and then tested them against a wide range of antibiotics to see which drugs could still stop the growth of the germs. They also looked for signs of the specific enzymes that break down antibiotics, paying close attention to whether the bacteria were resistant to multiple drug classes or had developed the ability to produce these destructive enzymes.

The results revealed a heavy burden of resistance in the region. The most common bacteria found were E. coli, which made up more than a third of all samples, and Klebsiella pneumoniae, which accounted for nearly a quarter. When tested against older, commonly used antibiotics, the bacteria showed very high levels of resistance. For instance, more than 80 percent of the bacteria were immune to ampicillin, and over 70 percent resisted both cefoxitin and a combination drug called trimethoprim–sulfamethoxazole. However, the situation was not hopeless; the bacteria remained mostly susceptible to newer, stronger antibiotics like meropenem and imipenem, with resistance rates for these drugs staying below 11 percent. Despite the effectiveness of these newer drugs, the overall picture was alarming. Nearly 80 percent of the bacteria collected were classified as multidrug-resistant, meaning they could survive at least three different types of antibiotics. Even more concerning, almost half of all the isolates were extensively drug-resistant, showing resistance to almost every category of antibiotic tested.

The study also uncovered the specific mechanisms driving this resistance. The researchers found that a significant portion of the bacteria were producing enzymes that break down antibiotics. About 20 percent of the bacteria capable of producing extended-spectrum beta-lactamases, a type of enzyme that destroys many common antibiotics, were identified. An even larger group, nearly 40 percent of the bacteria, showed signs of producing a different type of enzyme called AmpC, which is particularly difficult to treat because it is not stopped by the usual chemical inhibitors used in combination drugs. The data showed a clear link between these enzyme-producing bacteria and the high rates of multidrug resistance. Bacteria that produced these enzymes were significantly more likely to be resistant to multiple drugs than those that did not. This pattern was consistent across different species, with Acinetobacter baumannii and Klebsiella pneumoniae showing the highest rates of multidrug and extensive drug resistance.

The findings paint a clear picture of a region where standard treatments are increasingly failing, yet effective options still exist if they are used carefully. The study highlights that while the newer carbapenem antibiotics remain effective against most of these bacteria, the high prevalence of multidrug resistance and the presence of destructive enzymes mean that doctors cannot rely on guesswork or old standards of care. The researchers emphasize that the high rates of resistance observed in these regional hospitals differ from what might be seen in larger, tertiary hospitals, suggesting that local conditions and antibiotic use patterns play a major role. To protect patients, the study concludes that these facilities need stronger systems to track which bacteria are circulating and which drugs work best. By regularly testing bacteria and using the results to guide treatment, hospitals can preserve the effectiveness of the remaining antibiotics and prevent the spread of these highly resistant organisms.