Hyperammonemia syndrome associated with Ureaplasma spp. Infections in immunocompromised patients and transplant recipients: A systematic review and meta-analysis

Ureaplasma urealyticum infection following organ transplantation: a case report and narrative review

OBJECTIVE

One case of Ureaplasma urealyticum (UU) infection after kidney transplantation was reported, and relevant literature was collected to provide a scientific reference basis for clinical diagnosis and treatment.

METHODS

A case of UU infection after renal transplantation in our hospital was analyzed retrospectively. PubMed, Embase and Cochrane databases were searched for case reports of UU infection after organ transplantation before 30 June 2024. The clinical and laboratory characteristics, treatment and prognosis of UU infection were summarized and analyzed.

RESULTS

A 65-year-old man underwent renal transplantation on 26 January 2022 due to chronic renal disease (grade 2) caused by focal sclerosing glomerulonephritis. Hyperammonaemia and coma occurred after the operation, and the patient died. A total of 38 case reports or series of cases were included in this study, involving 44 patients. The case reports included 22 cases of kidney transplantation, 11 cases of lung transplantation, 4 cases of heart transplantation,1 case of liver transplantation and 6 cases of multiple organ transplantation. Ureaplasma urealyticum infection occurred in 74.47% of cases within 1 month after transplantation, and the main symptoms after the infection were mental. After the onset of the disease, the most abnormal examination index was the increase of blood ammonia, followed by the increase of white blood cells. Therapeutic drugs included tetracyclines (doxycycline or minocycline), quinolones and azithromycin. The clinical symptoms could be significantly improved after 24 h of taking the fastest-acting medication. The highest mortality rate was in patients infected with Ureaplasma after lung transplantation.

CONCLUSION

Early identification of UU and timely and correct drug treatment are essential to saving the lives of patients.

Donor-derived Mycoplasma and Ureaplasma infections in lung transplant recipients: A prospective study of donor and recipient respiratory tract screening and recipient outcomes

Mycoplasma hominis and Ureaplasma species are urogenital mollicutes that can cause serious donor-derived infections in lung transplant recipients. Best practices for mollicute screening remain unknown. We conducted a single-center prospective study analyzing lung transplants performed from October 5, 2020, to September 25, 2021, whereby donor and recipient bronchoalveolar lavage (BAL) samples obtained at time of transplant underwent mollicute screening via culture and polymerase chain reaction (PCR). Of 115 total lung transplants performed, 99 (86%) donors underwent combined mollicute BAL culture and PCR testing. The study cohort included these 99 donors and their matched recipients. In total, 18 (18%) of 99 donors screened positive via culture or PCR. Among recipients, 92 (93%) of 99 had perioperative BAL screening performed, and only 3 (3%) had positive results. After transplant, 9 (9%) recipients developed mollicute infection. Sensitivity of donor screening in predicting recipient mollicute infection was 67% (6/9) via culture and 56% (5/9) via PCR. Positive predictive value for donor culture was 75% (6/8), compared with 33% (5/15) for PCR. Donor screening via culture predicted all serious recipient mollicute infections and had better positive predictive value than PCR; however, neither screening test predicted all mollicute infections. Independent of screening results, clinicians should remain suspicious for posttransplant mollicute infection.

Dual Dialysis for Post-bilateral Orthotopic Lung Transplantation Hyperammonemia

Hyperammonemia is a metabolic disorder characterized by supraphysiologic ammonia (NH3) concentrations in the blood. Although usually seen in adults with liver disease, hyperammonemia is a notable complication in 4.1% of lung transplants. It is associated with cerebral edema and neurological dysfunction and carries up to 75% mortality in critically ill patients. Opportunistic infections caused by Mycoplasma and Ureaplasma species have been implicated as the cause of this metabolic disturbance. Literature in neonates has shown that renal replacement therapy (RRT) is the best choice for treating patients with neurologic manifestations of hyperammonemia, in cases of NH3 clearance than continuous renal replacement therapy (CRRT). In contrast, continuous venovenous hemodialysis (CVVHD) is usually better tolerated for patients with hemodynamic instability for NH3 clearance. NH3 is a small molecule whose clearance mirrors urea in dialysis. Even though RRT can be a treatment modality for hyperammonemia in adults and neonates, there is very little literature on adults. We present a unique case demonstrating improvement in neurologic manifestations of hyperammonemia by using both IHD and CVVHD in an adult patient.

Mollicutes-related infections in thoracic surgery including lung and heart transplantation: A systematic review

BACKGROUND

Urogenital Mollicutes, that is, Mycoplasma hominis and Ureaplasma spp., can colonize the urogenital tract. While urogenital colonization is frequent, infections are rare but should not be missed. Furthermore, extragenital infections are even rarer. Over the past years, they have been increasingly documented as a cause of hyperammonemia syndrome (HS) and post-surgical infections. We review the literature on studies focused on post-surgical infections and HS involving urogenital Mollicutes after thoracic surgery including lung (LTR) and heart (HTR) transplantation.

METHODS

A systematic review was performed by searching PubMed/Medline case reports, case series, cohort studies, and clinical trials. Cases of infections and HS by urogenital Mollicutes after HTR and LTR transplantations were reported.

RESULTS

Overall, urogenital Mollicutes were associated with 15 HS, 31 infections in HTR and LTR, and 18 post-thoracic surgical infections in another context. Post-surgical infections were reported in all contexts. They were mainly due to M hominis, the only species that could cultivate on standard enriched agar forming pinpoint colonies after 3-5 days of incubation. Microbiologists should be prompted to pinpoint colonies even if the examination of Gram-staining is negative. The patients' management required surgical treatment and antimicrobials, almost always tetracyclines and/or fluoroquinolones. Conversely, HS occurred almost exclusively in bilateral LTR and is more likely due to Ureaplasma spp. As Ureaplasma spp. do not cultivate on standard media, the microbiological diagnosis was performed using molecular methods.

CONCLUSIONS

Infections involving urogenital Mollicute should be considered in LTR with HS. The overall rate of mortality is high and might be due in part to delay in etiologic diagnosis. Post-surgical infections were reported in all contexts. The route of contamination with Mollicutes remains unknown in HTR and non-transplant surgery, but evidence of transmission from donors has been documented for LTR.

Mycoplasma and Ureaplasma Donor-Derived Infection and Hyperammonemia Syndrome in 4 Solid Organ Transplant Recipients From a Single Donor

Hyperammonemia syndrome (HS) is a life-threatening condition occurring in solid organ transplant patients, affecting primarily lung recipients, and is associated with Mycoplasma hominis and/or Ureaplasma spp infection. The organ donor was a young man who died of hypoxic brain injury and had urethral discharge antemortem. The donor and 4 solid organ transplant recipients had infection with M hominis and/or Ureaplasma spp. The lung and heart recipients both developed altered conscious state and HS associated with M hominis and Ureaplasma spp infections. Despite treatment with antibiotics and ammonia scavengers, both the lung and heart recipients died at day +102 and day +254, respectively. After diagnosis in the thoracic recipients, screening samples from the liver recipient and 1 kidney recipient were culture positive for M hominis with or without Ureaplasma spp. Neither the liver nor kidney recipients developed HS. Our case series demonstrates the unique finding of M hominis and Ureaplasma spp dissemination from an immunocompetent donor across 4 different organ recipients. Phylogenetic whole genome sequencing analysis demonstrated that M hominis samples from recipients and donor were closely related, suggesting donor-derived infection. Screening of lung donors and/or recipients for Mycoplasma and Ureaplasma spp is recommended, as well as prompt treatment with antimicrobials to prevent morbidity.

Prevalence of Mycoplasma hominis, Ureaplasma urealyticum, and Ureaplasma parvum detection in urine and respiratory tract samples in Hiroshima, Japan

Background

Mycoplasma hominis, Ureaplasma parvum, and Ureaplasma urealyticum are commensal bacteria that are associated with colonization and infection of the urogenital tract. However, colonization of the respiratory tract by these microorganisms in adults has not been fully investigated.

Methods

Urine and respiratory tract samples (sputum, tracheal aspirates, and bronchoalveolar lavage) of patients aged 20-80 years were analyzed to detect the presence of M. hominis, U. parvum, and U. urealyticum using a conventional PCR method. The samples were submitted to the microbiological clinical laboratory of Hiroshima University Hospital from December 1, 2021 to May 31, 2022.

Results

In total, 334 urine and 238 respiratory tract samples were analyzed. The overall detection rates of M. hominis, U. parvum, and U. urealyticum were 2.9%, 1.7%, and 2.3% in male urine; 7.0%, 13.8%, and 1.9% in female urine; 2.2%, 0%, and 2.2% in male respiratory tract; and 0%, 2.0%, and 0% in female respiratory tract, respectively. In urine samples, the detection rates of M. hominis, U. parvum, and U. urealyticum were significantly higher (p < 0.001) for women (29/159; 18.2%) than for men (10/175; 5.7%); however, in respiratory tract samples, the detection rates were not significantly different (p = 0.70) between women (2/101; 2.0%) and men (5/137; 3.7%). Further, both the urine and respiratory samples of 83 patients were analyzed. Three male samples were positive for M. hominis or U. urealyticum, and M. hominis and U. urealyticum were matched in both the urine and respiratory tract samples: M. hominis (n = 1), U. urealyticum (n = 1), M. hominis + U. urealyticum (n = 1).

Conclusion

M. hominis, U. parvum, and U. urealyticum were detected in the respiratory tract of not only the young patients, but also of patients aged 50-60 years. Further studies are required to understand the relationship of these microorganisms in urogenital and respiratory tract samples with extra-genital infections.

Hyperammonemia in a septic patient with Ureaplasma parvum arthritis: a case report

BACKGROUND

Septic arthritis requires prompt diagnosis and treatments. Rare pathogens should be considered when patients respond poorly to the initial antibiotic treatments. Ureaplasma parvum is an opportunistic pathogen that commonly resides in the human urogenital tract. Its infection commonly causes hyperammonemia. Hyperammonemia from Ureaplasma parvum septic arthritis has never been reported previously.

CASE PRESENTATION

A 65-year-old male presented with fever and left lower leg pain and swelling for more than ten days. Septic arthritis and sepsis were considered after laboratory tests and arthrocentesis. However, he responded poorly to the antibiotic treatments, including cefoperazone-sulbactam, imipenem-cilastatin, and linezolid. His mental status deteriorated rapidly with elevated blood ammonia levels with unremarkable liver function test and sonogram examination results. Despite the treatments with lactulose, L-ornithine L-aspartate, mannitol, and hemodialysis therapy to lower his ammonia level, his blood ammonia level remained persistently high. Finally, metagenomic sequencing of the left knee synovial fluid reported Ureaplasma parvum, which was considered to contribute to his hyperammonemia.

CONCLUSION

Ureaplasma parvum could cause septic arthritis with hyperammonemia. Genetic tests, such as polymerase chain reaction and next-generation sequencing techniques, could provide a sensitive and fast diagnosis of Ureaplasma parvum.

Hyperammonemia syndrome post-lung transplantation: Case series and systematic review of literature

BACKGROUND

Hyperammonemia syndrome (HS) is a rare post-transplant complication associated with high morbidity and mortality. Its incidence appears to be higher in lung transplant recipients and its pathophysiology is not well understood. In addition to underlying metabolic abnormalities, it is postulated that HS may be associated with Ureaplasma or Mycoplasma spp. lung infections. Management of this condition is not standardized and may include preemptive antimicrobials, renal replacement, nitrogen scavenging, and bowel decontamination therapies, as well as dietary modifications.

METHODS

In this case series, we describe seven HS cases, five of whom had metabolic deficiencies ruled out. In addition, a literature review was performed by searching PubMed following PRISMA-P guidelines. Articles containing the terms "hyperammonemia" and "lung" were reviewed from 1 January 1997 to 31 October 2021.

RESULTS

All HS cases described in our center had positive airway samples for Mycoplasmataceae, neurologic abnormalities and high ammonia levels post-transplant. Mortality in our group (57%) was similar to that published in previous cases. The literature review supported that HS is an early complication post-transplant, associated with Ureaplasma spp. and Mycoplasma hominis infections and of worse prognosis in patients presenting cerebral edema and seizures.

CONCLUSION

This review highlights the need for rapid testing for Ureaplasma spp. and M. hominis after lung transplant, as well as the necessity for future studies to explore potential therapies that may improve outcomes in these patients.

Ureaplasma urealyticum infection presenting as altered mental status in a post-chemotherapy patient: Case report and literature review

Hyperammonemia due to Ureaplasma infection is rare but often fatal, largely due to the delayed recognition, diagnosis, and treatment of the condition. It has mostly been described in solid organ transplant patients in the literature. This case presents the diagnostic challenge of an immunocompromised patient with previous resected pancreatic head adenocarcinoma and chemotherapy, presenting with altered mental status due to hyperammonemia from Ureaplasma infection. It is imperative to consider this condition in unexplained hyperammonemia, especially in immunocompromised patients. Timely diagnosis of this condition can help to reduce complications from encephalopathy such as cerebral edema and seizures.

Case Report: Hyperammonemic Encephalopathy Linked to Ureaplasma spp. and/or Mycoplasma hominis Systemic Infection in Patients Treated for Leukemia, an Emergency Not to Be Missed

Background

Hyperammonemic encephalopathy caused by Ureaplasma spp. and Mycoplasma hominis infection has been reported in immunocompromised patients undergoing lung transplant, but data are scarce in patients with hematological malignancies.

Case Presentation

We describe the cases of 3 female patients aged 11–16 years old, developing initially mild neurologic symptoms, rapidly evolving to coma and associated with very high ammonia levels, while undergoing intensive treatment for acute leukemia (chemotherapy: 2 and hematopoietic stem cell transplant: 1). Brain imaging displayed cerebral edema and/or microbleeding. Electroencephalograms showed diffuse slowing patterns. One patient had moderate renal failure. Extensive liver and metabolic functions were all normal. Ureaplasma spp. and M. hominis were detected by PCR and specific culture in two patients, resulting in prompt initiation of combined antibiotics therapy by fluoroquinolones and macrolides. For these 2 patients, the improvement of the neurological status and ammonia levels were observed within 96 h, without any long-term sequelae. M. hominis was detected post-mortem in vagina, using 16S rRNA PCR for the third patient who died of cerebral edema.

Conclusion

Hyperammonemic encephalopathy linked to Ureaplasma spp. and M. hominis is a rare complication encountered in immunocompromised patients treated for acute leukemia, which can lead to death if unrecognized. Combining our experience with the few published cases (n=4), we observed a strong trend among female patients and very high levels of ammonia, consistently uncontrolled by classical measures (ammonia-scavenging agents and/or continuous kidney replacement therapy). The reversibility of the encephalopathy without sequelae is possible with prompt diagnosis and adequate combined specific antibiotherapy. Any neurological symptoms in an immunocompromised host should lead to the measurement of ammonia levels. If increased, and in the absence of an obvious cause, it should prompt to perform a search for Ureaplasma spp. and M. hominis by PCR as well as an immediate empirical initiation of combined specific antibiotherapy.

Hyperammonemia syndrome in immunosuppressed individuals

PURPOSE OF REVIEW

Hyperammonemia syndrome is an increasingly recognized and often fatal condition that occurs in immunosuppressed individuals, most commonly lung transplant recipients. Growing evidence suggests hyperammonemia syndrome is associated with systemic infections caused by urease-producing organisms, namely Ureaplasma spp., an organism unable to grow with routine culturing techniques. This review will summarize the epidemiology and clinical manifestations of hyperammonemia syndrome, as well as diagnostic and management strategies once hyperammonemia syndrome is suspected.

RECENT FINDINGS

Hyperammonemia syndrome is being described in increasing frequency in the solid organ transplant population. Morbidity and mortality, even with treatment, is high once hyperammonemia syndrome occurs. Surveillance studies indicate the prevalence of lung donor colonization with Ureaplasma spp. is high, suggesting screening and treatment may be of benefit. Antibiotic resistance is common, and rapid diagnostics can facilitate appropriate antimicrobial therapy in the peri-transplant period.

SUMMARY

Hyperammonemia syndrome is most commonly seen in lung transplant recipients and has a high mortality rate once it occurs. Screening for Ureaplasma spp. should be considered in all lung transplant donors.