Pantoea agglomerans infection: a rare case of infection in a totally implantable venous access port

Introduction

For patients with cancer or those requiring long-term intravenous therapy, repeated venipuncture and drug-induced irritation increase both patient discomfort and technical challenges of venous access. The clinical introduction of totally implantable venous access ports (PORTs) has addressed many of these issues, offering reduced puncture-related pain, longer device lifespan, and simplified daily management, leading to widespread clinical adoption (1,2). However, complications, particularly infections, may arise during PORT implantation and use, with infection being the most frequently encountered complication (3). Pantoea agglomerans (P. agglomerans) is primarily an environmental and agricultural organism that rarely causes diseases in immunocompetent individuals (4). Clinical infections caused by P. agglomerans are rare. Here, we report a rare case of P. agglomerans infection involving a PORT reservoir. We present this article in accordance with the CARE reporting checklist (available at https://acr.amegroups.com/article/view/10.21037/acr-2026-0006/rc).

Case presentation

On August 7, 2023, a 72-year-old postoperative breast cancer patient was admitted for the fifth cycle of chemotherapy following bilateral breast surgery. The chemotherapy regimen consisted of liposomal doxorubicin hydrochloride and cyclophosphamide. The patient tolerated the treatment well without significant adverse effects during chemotherapy. Upon admission, the patient was afebrile and in good general condition. On the second day of hospitalization, after blood was drawn via the PORT, the patient developed sudden chills and high fever, with a peak temperature of 39.5 ℃. Ultrasonography indicated localized effusion in the chest wall, while chest computed tomography (CT) suggested possible mild pulmonary infection. The patient’s body temperature decreased after anti-infective therapy.

On the fourth day of hospitalization, the patient developed recurrent high fever again up to 38.8 ℃ following infusion via the PORT. Blood tests, including complete blood count (CBC) and high-sensitivity C-reactive protein, showed leukocytosis with a white blood cell count of 10.13×10⁹/L, absolute neutrophil count of 9.83×10⁹/L, neutrophil percentage of 97.0%, and elevated C-reactive protein level of 35.87 mg/L. Blood cultures were obtained via the PORT using a single-bottle bilateral protocol. After consultation with the respiratory department, the patient was suspected to have a respiratory viral infection, and oseltamivir was recommended for anti-infective treatment. The chemotherapy cycle was therefore temporarily postponed.

On the sixth day of hospitalization, the laboratory reported a critical result: gram-negative bacilli were detected in the blood culture, while identification of the specific bacterial species and antimicrobial susceptibility required further testing. Given suspected bacteremia, antibiotics were changed to biapenem. On day 5 of incubation, P. agglomerans was identified and demonstrated broad susceptibility to antibiotics (Table 1). Follow-up blood tests showed improved inflammatory markers, suggesting that biapenem was effective against the infection. Given that the patient only developed high fever following the PORT procedure, which differs from typical bacteremia cases. To investigate the cause, Subsequent blood cultures were obtained via both the PORT and peripheral veins (two sets: aerobic and anaerobic bottles from bilateral sites) concurrently when the patient developed a high fever again. After 3 days of incubation, P. agglomerans was isolated exclusively from the anaerobic culture obtained via the PORT, while all other cultures remained negative. According to this result, we hypothesized that P. agglomerans colonized the interior of the PORT reservoir, with pathogens entering the bloodstream only during invasive procedures. Following antibiotic therapy, the patient’s body temperature normalized.

On August 21, due to the suspicion of PORT-related infection, the patient underwent “implantable port removal”. The explanted PORT was sent for culture. P. agglomerans was isolated from the reservoir body but not from the catheter. Meanwhile, additional screening for other potential infection sources was performed, but no P. agglomerans infection was identified elsewhere (Table 2). This differential result confirmed our aforementioned hypothesis. Following infection control and PORT removal, the patient resumed and completed chemotherapy without complications. Throughout the treatment course, the patient remained in a stable condition with no further febrile episodes. All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Helsinki Declaration and its subsequent amendments. Written informed consent was obtained from the patient for publication of this case report and accompany images. A copy of the written consent is available for review by the editorial office of this journal.

Discussion

P. agglomerans is a gram-negative aerobic bacillus that belongs to the Enterobacteriaceae family and is an opportunistic pathogen (5,6). In clinical settings, it primarily causes infections in immunocompromised individuals, such as children, patients with multiple traumas, malignancies, and those undergoing long-term immunosuppressive therapy. Infections may also occur due to catheterization, surgical procedures, or transfusion of contaminated blood products (7). Previous case reports have described P. agglomerans infections as typically causing severe bacteremia (8). Epidemiological investigations indicate that infections with this bacterium in cancer patients mostly occur in sporadic or outbreak forms. A typical outbreak was the cluster of infections at an oncology clinic in Illinois, USA, which was traced back to breaches in aseptic technique (9). In the present case, the patient underwent adjuvant chemotherapy after tumor resection. Chemotherapy-induced immunosuppression likely predisposed her to P. agglomerans infection. This highlights the need to further standardize procedures for immunocompromised cancer patients to prevent opportunistic infections. Interestingly, this patient did not exhibit severe bacteremia but only developed high fever after invasive procedures, remaining afebrile at other times. In general, chills, high fever, and leukocytosis occur after accessing or maintaining a venous PORT suggest a catheter-related bloodstream infection (CRBSI). The underlying mechanism involves bacterial colonization of the intravascular catheter, originating from skin flora at the puncture site (10). In such cases, peripheral blood cultures must be positive and yield the same pathogens as catheter-drawn blood cultures. Seven cases of infection associated with central venous catheters (CVCs) have been reported in Italy: the cases exhibited positive catheter-drawn blood cultures but negative peripheral blood cultures (11). However, our case differs in two key aspects. First, in contrast to that report, our comparative blood cultures (catheter vs. peripheral) were obtained during febrile episodes concurrently that can exclude transient or intermittent bacteremia. Second, P. agglomerans was cultured from the catheter in their cases while was found exclusively within the PORT reservoir in ours, confirming that the bacterium colonized in this location. To summarize, our case represented a manifestation of P. agglomerans infection that has been rarely reported and underrecognized.

The potential reasons for the unique colonization sites of P. agglomerans can be considered as follows. First, P. agglomerans has been identified as the predominant bacterium in cotton plants worldwide and can be found in feces, soil, and various animals, such as insects and domestic animals, both internally and on their surfaces (12). It is also associated with “cotton fever”, a benign febrile response to endotoxin production following the introduction of cotton into the bloodstream (13). This can occur when cotton is used to filter substances before intravenous injection. In a case of P. agglomerans infection associated with a PORT, the patient underwent chemotherapy for carcinoma of ampulla of vater with secondary metastasis to lungs. Kundu et al. speculated that the use of cotton balls during the procedure might be the source (14). In our case, the patient developed high fever after each invasive procedure involving the PORT reservoir, and the site was disinfected with povidone-lodine cotton balls before and after each invasive procedure. One possible contributing factor is the use of cotton filtration in intravenous drug administration. Second, based on the findings that P. agglomerans is present within the PORT chamber but absent from the catheter, we hypothesized that anti-reflux valve contributed to preventing bacteria from entering the bloodstream. P. agglomerans generally shows good susceptibility to a broad range of antibiotics. However, P. agglomerans can acquire resistance through the production of extended-spectrum beta-lactamases (ESBLs) and reduced susceptibility to carbapenems. In 2012, a Nigerian study reported the detection of the blaCTX-M-15 gene in clinical isolates of P. agglomerans, confirming that resistance genes can be transferred via conjugation and pose a risk of spread to other Enterobacteriaceae (15). In 2024, India reported the first case of carbapenem-resistant P. agglomerans bloodstream infection harboring blaOXA-181, with all isolates being resistant to third-generation cephalosporins (16). What’s more, P. agglomerans exhibits reduced susceptibility to carbapenems, with clinical isolates demonstrating intermediate or resistant phenotypes to imipenem and meropenem. In 2014, Mardaneh et al. reported that 37.5% of P. agglomerans strains isolated from infant formula showed reduced susceptibility to meropenem and 25% were intermediate to imipenem (17). More recently, Mallick et al. described the first carbapenem-resistant P. agglomerans bloodstream infection in India harboring blaOXA-181, with 57.1% (4/7) of isolates being carbapenem-resistant (16). Additionally, in Neonates, Pantoea strains exhibit resistance to carbapenems, trimethoprim/sulfamethoxazole stands as a potential alternative (18). As a result, empirical therapy should be guided by antimicrobial susceptibility testing (AST) results whenever possible. For Pantoea-related bloodstream infections associated with intravenous catheters, prompt catheter removal is essential, followed by targeted antibiotic therapy. With appropriate and timely treatment, the prognosis is favorable, and mortality rates remain low, even among immunocompromised patients.

Conclusions

In conclusion, P. agglomerans is a rare pathogen that causes a range of clinical infections, with bacteremia being its most typical manifestation. In this case report, however, P. agglomerans colonized the PORT reservoir, leading to recurrent high-grade fever only during invasive procedures. This represents a novel form of infection caused by this bacterium. Aseptic technique, prompt antibiotic therapy and removal of the PORT are crucial for controlling infection.

Acknowledgments

None.

Footnote

Reporting Checklist: The authors have completed the CARE reporting checklist. Available at https://acr.amegroups.com/article/view/10.21037/acr-2026-0006/rc

Peer Review File: Available at https://acr.amegroups.com/article/view/10.21037/acr-2026-0006/prf

Funding: This study was supported by Changzhou Applied Basic Research Project (No. CJ20243021).

Conflicts of Interest: Both authors have completed the ICMJE uniform disclosure form (available at https://acr.amegroups.com/article/view/10.21037/acr-2026-0006/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Helsinki Declaration and its subsequent amendments. Written informed consent was obtained from the patient for publication of this case report and accompany images. A copy of the written consent is available for review by the editorial office of this journal.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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