CDC Warns of Spreading Drug-Resistant Stomach Illness

An estimated 450,000 Americans contract shigellosis each year [1]. Most recover within a week. But a growing fraction of those infections now resist every standard antibiotic doctors can prescribe — and the federal government has no approved drug to offer them.

On April 9, 2026, the Centers for Disease Control and Prevention published findings in its Morbidity and Mortality Weekly Report showing that extensively drug-resistant (XDR) Shigella infections have risen sharply in the United States [2]. Among 16,788 isolates tested between 2011 and 2023, XDR strains climbed from 0% to 8.5% — with 84% of all XDR cases concentrated in 2022 and 2023 [2]. No FDA-approved oral antimicrobial agent exists to treat them [2].

What XDR Shigella Is and Why It Matters

Shigella is a gram-negative bacterium that causes shigellosis, an inflammatory diarrheal illness marked by bloody stool, fever, and abdominal cramping [3]. Symptoms typically begin one to two days after exposure. The bacterium spreads through the fecal-oral route — contact with an infected person's stool, contaminated food, or contaminated water — and the infectious dose is remarkably low, as few as 10 to 100 organisms [4].

Extensively drug-resistant, or XDR, means the bacterium is resistant to all five oral antibiotics clinicians typically turn to: ampicillin, azithromycin, ceftriaxone, ciprofloxacin, and trimethoprim-sulfamethoxazole [2]. An additional 32.7% of XDR isolates also showed resistance to chloramphenicol [2]. The designation leaves physicians with no standard oral treatment and only limited, non-FDA-approved alternatives.

The resistance mechanisms are both chromosomal and plasmid-borne. Ciprofloxacin resistance arises primarily through chromosomal mutations, while resistance to azithromycin and cephalosporins is carried on conjugative plasmids — mobile genetic elements that bacteria can transfer horizontally to unrelated species [5]. This means XDR Shigella can share its resistance toolkit with other gut bacteria, potentially accelerating the spread of untreatable infections beyond shigellosis itself [6].

Source: CDC MMWR

Data as of Apr 9, 2026CSV

Who Is Getting Sick

The demographic profile of XDR shigellosis differs markedly from traditional Shigella outbreaks, which historically affected young children. Among the 510 XDR cases identified in the CDC's study, 86.2% occurred in adult men, with a median age of 41 years [2]. Only 3.9% of cases involved patients under 18 [2].

Among individuals with available clinical data, 46.6% were co-infected with HIV [2]. A significant proportion of cases involved men who have sex with men (MSM), and clinicians have noted a heavy burden among people experiencing homelessness [1]. "We see more Shigella in persons experiencing homelessness than we do in any other at-risk population," said Dr. Ferric Fang, as reported by CIDRAP [1].

The hospitalization rate was 37.6% — roughly one in three patients with available outcome data required inpatient care [2]. No deaths were reported among XDR cases during the study period [2].

Geographically, cases have been reported across the Northeast, Midwest, South, and West regions [2]. More than 76% of patients reported no recent domestic travel, and 82% reported no international travel, indicating sustained domestic transmission rather than imported cases [2]. In Los Angeles, UCLA Health clinicians documented a single XDR case in 2022; by 2026, they were seeing approximately one new case per month [1]. Dr. Shangxin Yang of UCLA Health described the trend: "It's almost like an explosion of this pathogen in the community" [1].

The Species Breakdown

Two Shigella species account for all XDR cases. S. sonnei comprised 65.9% and S. flexneri 34.1% [2]. The distribution varies by region: S. flexneri reached 84.6% of XDR isolates in the Northeast in 2021 and 54.8% in the West by 2023 [2]. A 2024-2025 study in Los Angeles identified a novel XDR S. sonnei genotype carrying the AmpC-type blaDHA-1 gene in two unrelated patients, one of whom had no MSM history — suggesting the pathogen is spreading into broader populations [7].

Treatment: What's Left

For patients with drug-susceptible shigellosis, the illness typically resolves in five to seven days without antibiotics [8]. Antimicrobials shorten symptom duration by about two days and reduce the period of fecal shedding, lowering transmission risk [8].

For XDR cases, the calculus changes. Three drugs have shown potential effectiveness: pivmecillinam, fosfomycin, and oral carbapenems such as sulopenem [1][2]. None is FDA-approved for shigellosis. The CDC's study found no meropenem or fosfomycin resistance among tested XDR isolates, providing a narrow window of therapeutic possibility [2].

The timeline for losing even these options is uncertain. Resistance to carbapenems — often described as "last-resort" antibiotics — has surged in other bacterial families. NDM-producing carbapenem-resistant Enterobacterales (NDM-CRE) infections increased by more than 460% in the United States between 2019 and 2023 [9]. Because Shigella shares its gut environment with Enterobacterales that already carry carbapenem resistance genes, the potential for horizontal gene transfer raises the prospect that even these backup treatments could eventually fail.

The CDC's contingency guidance centers on antimicrobial susceptibility testing (AST) for every confirmed case, so clinicians can identify which drugs — if any — remain effective for the specific strain a patient carries [2][10].

A Global Problem Arriving Domestically

XDR Shigella is not unique to the United States. Multidrug-resistant strains have circulated widely in South and Southeast Asia for years, where ciprofloxacin resistance rates increased by 40% between 2009 and 2016, and azithromycin resistance climbed from 22% to roughly 60% over the same period [5]. The UK reported a sharp increase in sexually transmitted XDR Shigella cases in March 2026 [1].

The domestic trajectory mirrors what countries with higher baseline resistance have experienced — but with a lag. The U.S. went from zero detected XDR isolates to 8.5% prevalence in under a decade [2]. Research output on Shigella drug resistance has tracked the growing threat: academic publications peaked at 4,255 papers in 2023, up from 684 in 2011 [11].

Source: OpenAlex

Data as of Jan 1, 2026CSV

Surveillance Gaps and the Delayed Alarm

The CDC first issued a Health Alert Network (HAN) advisory about XDR Shigella in February 2023 [10]. But the data underlying the April 2026 MMWR report covers 2011 through October 2023 — meaning the agency's formal published analysis arrived more than two years after data collection ended [2].

During that interval, clinicians on the ground were already witnessing accelerating caseloads. The gap between clinical reality and published federal surveillance reflects structural limitations in the U.S. infectious disease reporting infrastructure. Shigella "falls through the cracks" between sexually transmitted infection and foodborne illness classifications, as CIDRAP reported, limiting the coordinated public health response that either category alone would trigger [1].

The CDC tracks Shigella resistance through the National Antimicrobial Resistance Monitoring System (NARMS), and the AR Laboratory Network — which celebrated its 10th anniversary in 2026 — has performed 1.5 million tests to identify antimicrobial resistance [12]. But the reliance on state and local public health laboratories to submit isolates to PulseNet means reporting is neither universal nor real-time [2].

Federal Funding: Flat Despite a Growing Threat

The CDC's Antibiotic Resistance Solutions Initiative received $197 million in fiscal year 2026 — level funding for the third consecutive year [13][14]. That figure represents a modest increase from the $170 million allocated in FY2020 and FY2021, but falls well short of what professional organizations have requested [14].

Source: CDC / IDSA

Data as of Mar 1, 2026CSV

The American Society for Microbiology called for at least $400 million — more than double the current allocation [15]. The Infectious Diseases Society of America characterized the FY2026 outcome as "a victory" given the political environment, noting that overall CDC funding held steady at $9.2 billion and NIAID received $565 million for AMR research [13].

The cost of inaction is substantial. The CDC and researchers at the University of Utah estimate that treating just six priority antimicrobial resistance threats costs the U.S. healthcare system more than $4.6 billion annually [16]. A 2021 study found that drug-resistant infections led to $1.9 billion in healthcare costs, more than 400,000 hospital days, and over 10,000 deaths among older adults in a single year [17]. Globally, antimicrobial resistance adds an estimated $66 billion in healthcare costs annually, projected to reach $159 billion if resistance rates follow historical trends [18].

More than 2.8 million antimicrobial-resistant infections occur annually in the United States, causing over 35,000 deaths [12]. Shigella alone accounts for an estimated 450,000 infections per year [1].

The Case That the Warning Is Premature

Some clinicians and epidemiologists have raised questions about whether the CDC's alert risks doing more harm than good — not because the data is wrong, but because of how the public and prescribers may respond.

The core of this argument rests on several points. First, shigellosis is self-limiting in most patients. The CDC itself states that "people with Shigella infection usually get better without antibiotic treatment in 5 to 7 days" [8]. Among the 510 XDR cases identified in the MMWR study, zero deaths were reported [2]. The 37.6% hospitalization rate, while not trivial, must be read in context: the study population skewed heavily toward individuals with HIV co-infection and other comorbidities that independently increase hospitalization risk [2].

Second, there is a legitimate concern that public warnings about untreatable infections could drive "just-in-case" prescribing of the few remaining effective drugs — fosfomycin, pivmecillinam, oral carbapenems — accelerating resistance to those agents as well. This paradox sits at the center of antimicrobial stewardship: the very act of publicizing last-resort treatments can increase demand for them, eroding their effectiveness [6].

Third, XDR Shigella still represents a small share of total shigellosis — 8.5% of tested isolates as of 2023, or 510 confirmed cases over a 12-year period [2]. The vast majority of the estimated 450,000 annual infections remain treatable with standard antibiotics [1].

These arguments do not dismiss the underlying trend. They suggest that the framing and timing of public health communications carry their own risks, and that targeted clinical guidance — antimicrobial susceptibility testing before prescribing, focused outreach to high-risk populations — may be more effective than broad public alerts that could increase anxiety and inappropriate antibiotic use.

What Comes Next

The CDC's recommendations focus on prevention and precision: hand hygiene, safe food handling, antimicrobial susceptibility testing for every diagnosed case, and timely reporting by laboratories and clinicians [2]. For populations at elevated risk — MSM communities, people experiencing homelessness, individuals with HIV — targeted outreach and testing infrastructure will be critical.

The broader question is whether the U.S. public health system can move faster than the pathogen. XDR Shigella went from undetectable to 8.5% of tested samples in under a decade. The 84% concentration of cases in 2022-2023 suggests the curve is steepening, not flattening [2]. Federal AMR funding has been essentially flat since FY2024, and the pipeline for new oral antibiotics effective against gram-negative enteric pathogens remains thin [13][14].

Source: OpenAlex

Data as of Jan 1, 2026CSV

The scientific community has responded with intensified research — over 31,000 papers on Shigella drug resistance have been published since 2011, peaking at 4,255 in 2023 [11]. Whether that research translates into approved treatments before the current options are exhausted will determine whether XDR shigellosis remains a manageable public health concern or becomes a harbinger of the post-antibiotic era that microbiologists have warned about for decades.