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Severe necrotizing fasciitis was diagnosed in a 53-year-old man in Germany in 2012. Toxigenic Corynebacterium ulcerans was grown from a wound swab sample. One of the patient´s 2 dogs was found to harbor a toxigenic C. ulcerans strain. Results of next generation sequencing of both isolates supported recent zoonotic transmission of this bacterial pathogen.

To the Editor: Toxigenic Corynebacterium ulcerans may cause a zoonotic infection similar to diphtheria caused by C. diphtheriae. Previously, dairy cattle were considered to be the main reservoir for C. ulcerans (1), but recent publications suggest pet dogs and pet cats as carriers (cats often show bilateral nasal discharge) (2). We report a case of severe C. ulcerans diphtheria-like disease in a person who had had contact with pigs. In December 2007, a previously healthy 56-year-old female farmer was admitted to the Ear, Nose and Throat Department of the University Hospital Erlangen with a 1-week history of sore throat and progressive dysphagia. She did not report fever and had not received prior treatment with antimicrobial drugs. She had thick, whitish pseudomembranes on her uvula, pharynx, and both tonsils. Endoscopic examination of her larynx and hypopharynx showed that both vocal cords were mobile and the mucosa was erythematous. Enlarged cervical lymph nodes were palpable on both sides of her neck. She had no signs of cranial nerve palsies. Her temperature was 36.5°C. Because of the extensive oropharyngeal pseudomembranes, diphtheria was suspected and diphtheria antitoxin (30,000 IU) was administered intramuscularly. The patient was isolated and received intravenous penicillin (5 million units 4×/day). A pharyngeal swab obtained from below the whitish pseudomembranes grew toxigenic C. ulcerans. Species identification was achieved by biochemical differentiation (API Coryne code 0111326), rpoB sequencing (3), and MALDI-TOF analysis (Microflex LT and Biotyper 2.0 Software; Bruker Daltonics, Bremen, Germany). Toxigenicity of the strain, named KL126, was verified by using a C. diphtheriae tox–PCR (4–6), a C. ulcerans tox–specific PCR (4), and the Elek test as described previously (4,5). The tox sequence (GenBank accession no. {"type":"entrez-nucleotide","attrs":{"text":"FJ858272","term_id":"238817560","term_text":"FJ858272"}}FJ858272) differs from 2 other published C. ulcerans tox sequences ({"type":"entrez-nucleotide","attrs":{"text":"AB304279.1","term_id":"167216113","term_text":"AB304279.1"}}AB304279.1 and {"type":"entrez-nucleotide","attrs":{"text":"AY703827.1","term_id":"56694206","term_text":"AY703827.1"}}AY703827.1) at only 3 bp. The patient recovered quickly, and the pseudomembranes vanished within 2 days. However, because an allergic rash had developed after her third day of treatment with penicillin, antimicrobial drug treatment was switched to intravenous erythromycin (500 mg 4×/d). When 1 day later the standardized antibiogram showed resistance to erythromycin, the patient received intravenous ceftriaxone (2 g 1×/d) for 12 days. Seven days after initiation of antimicrobial drug therapy, pharyngeal swabs were taken on 3 consecutive days. Because C. ulcerans no longer grew on culture, the patient was discharged from the hospital. However, 2 days later she was readmitted to hospital for severe polyneuropathy with neuralgia and weakness of both arms, acute difficulty swallowing, and hoarseness. Signs of cardiomyopathy, including sinus bradycardia and grade I atrioventricular block, were present. The patient recovered after symptomatic treatment and returned home after 2 weeks. According to her records, the patient had received a basic vaccination against diphtheria in 1960 and a booster in 1998. The literature describes the classic animal sources for toxigenic C. ulcerans as dairy cattle with mastitis (1). Since 2005, toxigenic C. ulcerans carriage in companion animals, e.g., pet cats and dogs, has been reported (2). Two cases of transmission of a toxigenic C. ulcerans strain from pet dogs to their immunocompromised female owners have been documented in France (7,8). In 2008, toxigenic C. ulcerans in 2 dead killer whales from a Japanese zoo was reported (9). To determine the source of our patient’s illness, an outbreak investigation involving her family and their farm animals was conducted. Their medium-sized pig-breeding farm was located in a remote rural village surrounded by woods; they raised ≈500 pigs in a nonindustrialized manner, and no piglets were purchased from outside the farm. Pharyngeal swabs of 3 family members, 19 pigs, and the farm dog were analyzed for C. ulcerans. Although all family members and the dog were negative for C. ulcerans, 1 of the 19 asymptomatic pigs harbored a toxigenic strain of C. ulcerans. Sequencing of rpoB and tox showed 100% homology between the human and the pig strains. Ribotyping (10) confirmed this result, suggesting the identity of both strains; the obtained ribotype is similar to the reported U1 ribotype profile found in humans and cats (2). We report proven transmission of a toxigenic C. ulcerans strain between a livestock animal and a human, as well as harboring of toxigenic C. ulcerans in pigs. Introduction of C. ulcerans from wild animals seems unlikely because the barn doors were reportedly closed at all times. Because handling of C. ulcerans–infected pigs may lead to diphtheria-like illnesses, studies of toxigenic C. ulcerans carriage among pigs are needed. Similar to our case, diphtheria-like disease caused by an erythromycin- and clindamycin-resistant toxigenic C. ulcerans strain in a US patient has been recently (in 2008) reported (1). Because current recommendations based on C. diphtheriae–caused disease consider erythromycin as the second-line option for treatment or postexposure prophylaxis, these findings highlight the importance of antimicrobial-drug susceptibility testing of toxigenic C. ulcerans strains.

To the Editor: Enterohemorrhagic Escherichia coli (EHEC) can cause severe hemorrhagic colitis characterized by gastrointestinal symptoms and bloody diarrhea as well as hemolytic uremic syndrome (1). Cattle and small ruminants are the major natural reservoir of these foodborne pathogens (1,2). Human infections may also develop after direct contact with cows, goats, sheep, and deer (1). Although domestic dogs and cats are known as rare EHEC carriers (3,4), no human EHEC infections associated with pet contact have been reported. Here we report the first case of an EHEC strain infecting both a child and her domestic cat. A 2-year-old girl with bloody diarrhea and vomiting subsequently tested positive for EHEC serotype O145:H–. The isolated strain harbored the pathogenicity-associated genes stx1, stx2, eae, and hly, as tested by PCR. An enterohemolytic phenotype was also present. After notification of the local health authority, a rigorous search for the possible source of the girl’s infection was started. When asked for instances of animal contact, her parents mentioned the family cat, which the girl often handled. The cat is restricted to the house, has no contact with other animals, and is fed only canned catfood. The animal strictly uses a litter box, which is cleaned regularly by the parents. No gastrointestinal symptoms in the cat were recorded. Repeated stool samples from the cat grew a strain of EHEC O145:H– that showed the identical pathogenicity gene pattern as the girl’s isolate. Moreover, a restriction fragment length polymorphism analysis proved the clonal identity of both strains. Because both the girl and the cat continuously excreted the EHEC strain, the cat was assumed to be a possible source of the girl’s infection or reinfection. The cat’s’ infection was treated with probiotics, but the child’s EHEC positivity did not change. After 3 months, the girl spontaneously stopped excreting EHEC, while the cat’s stool samples remained EHEC positive. The cat was then treated by peroral autovaccination with the heat-inactivated EHEC strain for 10 consecutive days and subsequently stopped shedding EHEC. In the Table, the clinical course and laboratory findings of both girl and cat are summarized. Table Clinical picture and isolation of EHEC serotype O145:H– from stool samples of child and her cat* To our knowledge, this case is the first documented of an EHEC strain’s affecting both a human and a domestic cat. Both excreted EHEC for ≈3 months. Although the girl had vomiting and diarrhea, the cat was asymptomatic. Several possibilities regarding the infectious process can be noted. First, the girl might have contracted the disease from her asymptomatic pet. Although in a study on eae-positive E. coli strains, ≈6% of the investigated 62 cats tested positive, none of these cats was infected with EHEC serotype O145:H– (3); this finding indicates that in our case the cat might not have been the direct source for the girl’s infection. Moreover, foodborne transmission to the cat seems unlikely because it was exclusively fed with canned food that was heated during preparation. Second, the cat might have been infected by the girl. Although the prevalence of EHEC serotype O145:H– is relatively low, it ranks among the 6 most often isolated non–O157 EHEC strains in human infections, accounting for 5%–7% of all non–O157 EHEC strains in prevalence studies in Finland (5), Germany (6), and the United States (2,7). A similar epidemiologic pattern for EHEC serotype O145:H– is seen in cattle (2,8). Taken together, the prevalence of EHEC serotype O145:H– in cats, humans, and cattle might indicate that the girl was probably more likely the infection source for the cat than vice versa. Third, a cycle of mutual infection and reinfection between the girl and her pet cat cannot be ruled out. Although the excretion rate for EHEC changes over time and EHEC can therefore remain undetected in stool samples while still present within the patient, the child tested EHEC negative for a short period. Despite all the precautions taken, the girl may have been reinfected by the cat. This case illustrates several issues: 1) domestic animals such as cats (3), dogs (3,4), and rabbits (9) may serve as reservoirs for EHEC, irrespective of whether they are the primary or secondary source for these bacteria; 2) domestic cats as carriers may excrete EHEC for a prolonged period; 3) autovaccination may be effective for treating EHEC-infected animals; and 4) fondness for pets may be problematic: although EHEC O145:H– is among the 4 most often isolated EHEC serotypes associated with severe colitis or life-threatening hemolytic uremic syndrome (10), the girl’s parents, after weighing the infectious risks against the psychological benefits for both their daughter and her feline companion, decided not to send the cat to an animal shelter until its EHEC infection disappeared.