"A routine construction site injury led to an extraordinary medical case in Brazil, where an 88-year-old man developed blue sweat, a symptom attributed to a rare bacterial infection of his leg wound."
An unusual and alarming symptom, blue-tinged sweat, presented itself in an 88-year-old man in Brazil, seven days after he sustained an injury to the back of his right leg at a construction site. The peculiar discoloration, which also stained his skin and fingernails, was found to be removable with alcohol, though it would reappear. This case, detailed in a March publication in Cureus by Nathalia Madureira Ferraz and Danielli Oliveira da Costa Lino of Hospital de Messejana in Fortaleza, highlights a rare instance of pseudochromhidrosis potentially caused by the bacterium Pseudomonas stutzeri, an association previously undocumented. The patient’s condition improved dramatically within 24 hours of initiating targeted antibiotic treatment.
The Enigma of Colored Sweat
Sweat, typically a clear and odorless fluid produced by eccrine glands distributed across the body, serves a crucial thermoregulatory function. However, under certain circumstances, sweat can take on a variety of colors, a phenomenon known as chromhidrosis. This condition is broadly categorized into two types: true chromhidrosis and pseudochromhidrosis.
In true chromhidrosis, the color originates from pigments produced intrinsically within the body, which are then secreted through the sweat glands. This is less common and can be linked to various physiological or genetic factors. In contrast, pseudochromhidrosis, the likely diagnosis in this Brazilian case, occurs when sweat is initially colorless as it leaves the gland but acquires color on the skin’s surface. This coloration can result from external factors such as dyes, chemicals, or, as suggested in this instance, the metabolic byproducts of pigment-producing microorganisms colonizing the skin.
The observation that the blue discoloration could be wiped away with alcohol, only to return, was a pivotal clue for the attending physicians. This temporary removal strongly indicated that the pigment was present on the surface of the skin rather than being an inherent alteration within the sweat glands themselves. This distinction is critical in diagnosing the underlying cause of chromhidrosis.
The patient reported no prior episodes of colored sweat, nor had he consumed unusual foods or drinks, been exposed to dyes or chemicals, or started any new medications. His medical history included hypertension and prediabetes, but he explicitly stated that the bluish sweating began only after the leg injury. These details were crucial in ruling out common external causes and narrowing down the possibilities to an infection or a condition triggered by the wound.
Microbial Culprits Behind Colored Sweat
Infectious pseudochromhidrosis, where microorganisms are responsible for the color change, is a relatively rare occurrence. A comprehensive review published in Acta Dermato-Venereologica in 2020 shed light on the microbial landscape associated with this condition. The review identified four primary types of bacteria known to produce pigments that can color sweat, often as a result of complex interactions and competition among various microbes on the skin:
- Bacillus species: These bacteria have been linked to blue sweat.
- Corynebacterium: These are associated with brown or black discoloration.
- Serratia marcescens: This bacterium is known to cause red or pink sweat.
- Pseudomonas aeruginosa: A close relative of the bacterium identified in the Brazilian case, Pseudomonas aeruginosa has been implicated in blue-green sweat.
The authors of the Acta Dermato-Venereologica review also presented their own case, involving a patient whose blue sweat was attributed to a pigment-producing strain of Bacillus cereus. They emphasized that the development of this condition is often triggered by factors that disrupt the normal microbial balance of the skin, such as certain medications or underlying health conditions. Treatment typically involves addressing these triggers or employing antibiotic or antiseptic therapies.
The occurrence of blue sweat is not confined to any particular age group. A report from 2026 in the Journal of Pediatric Health Care documented a 17-year-old girl who experienced intermittent bright blue discoloration on her right elbow and upper arm following orthopedic injuries. This case also underwent extensive investigation before pseudochromhidrosis was identified as the cause.
Pseudomonas stutzeri: An Unexpected Contributor
Pseudomonas stutzeri, a rod-shaped bacterium first identified in 1895, is typically found in soil and water environments. It is not commonly isolated from clinical samples, and when it is detected, it often represents colonization or contamination rather than a true infection. A 2016 report in IDCases noted that in a hospital series, the vast majority of P. stutzeri isolates were considered to be incidental findings. However, despite its infrequent isolation, P. stutzeri has been implicated in clinically significant infections at various body sites. Furthermore, a 2020 case review highlighted that infections caused by this bacterium are particularly observed in individuals with compromised immune systems.
In the case of the 88-year-old Brazilian man, P. stutzeri was cultured from his infected leg wound, which had developed into cellulitis with an ulcer. Importantly, the isolated organism was found to be susceptible to quinolone antibiotics. Consequently, physicians initiated treatment with intravenous levofloxacin, a broad-spectrum fluoroquinolone antibiotic. The rapid and significant improvement in the blue discoloration within 24 hours of commencing this targeted therapy provided strong support for the hypothesis that P. stutzeri was indeed the culprit.
While this case provides compelling evidence, it is important to acknowledge the limitations of a single case report. The published summary did not specify which pigment, if any, was definitively identified. Therefore, the link between P. stutzeri and the blue sweat rests on the positive culture result from the infected wound, the temporal relationship between the injury and the onset of symptoms, and the prompt resolution of the discoloration following antibiotic treatment. Nevertheless, the authors posited that this case expands the known spectrum of infectious agents capable of causing chromhidrosis and underscores the critical importance of microbiological testing when patients present with unexplained changes in sweat color.
When to Seek Medical Attention for Colored Sweat
While colored sweat can be visually striking and alarming, it is often more of a curiosity than a serious health threat, especially when it can be easily washed away. However, the case of the Brazilian man illustrates that colored sweat can, in fact, be a marker of an underlying infection that requires medical intervention. His blue sweat was accompanied by cellulitis and an open ulcer, necessitating prompt treatment.
Any individual who notices their sweat or skin taking on an unusual color should consult a healthcare professional. This is particularly true if the discoloration is observed in proximity to a wound that exhibits signs of infection, such as redness, warmth, swelling, or fever. Older adults and individuals who have sustained cuts or abrasions, especially those acquired from soil or during construction work, should monitor any such injuries closely for signs of infection and seek medical care if they develop.
When evaluating a patient with colored sweat, clinicians will typically inquire about their diet, medication history, and any potential exposure to dyes or chemicals. If a wound is present, culturing the affected area is a standard procedure to identify any pigment-producing microbes that might be contributing to the discoloration. This thorough diagnostic approach ensures that the underlying cause is accurately identified and appropriately managed, preventing potential complications and restoring the patient’s health.
