Cardiothoracic Transplant Recipient Mycoplasma hominis: An Uncommon Infection with Probable Donor Transmission

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.

A rare case of postoperative Metamycoplasma hominis surgical site infection in a patient after bilateral lung transplantation

Following the COVID-19 infection, the sternum dislocation and wound dehiscence resulted in an infection complicating the recovery of an immunosuppressed patient after bilateral lung transplantation. Anaerobic culture (96 h) of milky cloudy wound secretion resulted in the growth of pinpoint haemolytic colonies identified as Metamycoplasma hominis (formerly Mycoplasma hominis). The search for the endogenous source of the infection found the bacterium exclusively in the patient's sputum, making a possible link to donor lung M. hominis colonization. Unfortunately, the donor samples were no longer available. The wound infection was successfully treated with 17 days of clindamycin despite the continuous PCR detection of M. hominis in the sputum after the end of the treatment.

Accurate etiological diagnosis of Mycoplasma hominis mediastinitis in immunocompetent patients using metagenomic next-generation sequencing: a case series and literature review

Background

As a culture-independent method, metagenomic next-generation sequencing (mNGS) is widely used in microbiological diagnosis with advantages in identifying potential pathogens, guiding antibiotic therapy, and improving clinical prognosis, especially in culture-negative cases. Mycoplasma hominis (M. hominis) mediastinitis is a rare and severe disease for which etiological diagnosis is important but challenging. The application of mNGS in the etiological diagnosis of mediastinitis has seldom been studied.

Methods

By searching the electronic medical history retrieval system with "Mycoplasma hominis" and "mediastinitis", seven patients diagnosed with M. hominis mediastinitis were reviewed in Zhongshan Hospital, Fudan University, Shanghai from 9 December 2020 to 14 February 2023. Microbiological cultures and mNGS were conducted for blood, abscess, and/or mediastinal fluid. Adjustment of the antibiotic therapy due to mNGS was assessed. A literature review was conducted in the PubMed database beginning in 1970 for M. hominis infection and mediastinitis.

Results

For the seven patients, cultures of blood, abscess, and mediastinal fluid were negative whereas mNGS identified M. hominis in serum, abscess, and/or mediastinal fluid and was used to guide specific antibiotic therapy. The stringent mapped reads number of genera (SMRNG), stringent mapped reads number of species (SMRN), and coverage rate of M. hominis detection by mNGS were significantly higher in body fluid (abscess or mediastinal fluid) than in serum. All seven patients had underlying heart diseases and underwent previous cardiac surgery. The most common symptoms were fever and sternal pain. After detection of M. hominis, antibiotics were adjusted to quinolones or doxycycline except for one patient, whose diagnosis was clarified after death. Two patients died. Literature review since 1970 identified 30 cases of extra-genital infection caused by M. hominis. Including our seven new cases, 2 (5.4%) were neonates and 35 (94.6%) were adults. Thirty (81.1%) cases were postoperative infection and 15 (40.5%) had implanted devices. Five patients (13.5%) died.

Conclusions

mNGS might be a promising technology in the detection of fastidious pathogens such as M. hominis. Accurate etiological diagnosis by mNGS could guide antibiotic therapy and facilitate clinical management.

Risk factors, management, and clinical outcomes of invasive Mycoplasma and Ureaplasma infections after lung transplantation

Mollicute infections, caused by Mycoplasma and Ureaplasma species, are serious complications after lung transplantation; however, understanding of the epidemiology and outcomes of these infections remains limited. We conducted a single-center retrospective study of 1156 consecutive lung transplants performed from 2010-2019. We used log-binomial regression to identify risk factors for infection and analyzed clinical management and outcomes. In total, 27 (2.3%) recipients developed mollicute infection. Donor characteristics independently associated with recipient infection were age ≤40 years (prevalence rate ratio [PRR] 2.6, 95% CI 1.0-6.9), White race (PRR 3.1, 95% CI 1.1-8.8), and purulent secretions on donor bronchoscopy (PRR 2.3, 95% CI 1.1-5.0). Median time to diagnosis was 16 days posttransplant (IQR: 11-26 days). Mollicute-infected recipients were significantly more likely to require prolonged ventilatory support (66.7% vs 21.4%), undergo dialysis (44.4% vs 6.3%), and remain hospitalized ≥30 days (70.4% vs 27.4%) after transplant. One-year posttransplant mortality in mollicute-infected recipients was 12/27 (44%), compared to 148/1129 (13%) in those without infection (P <.0001). Hyperammonemia syndrome occurred in 5/27 (19%) mollicute-infected recipients, of whom 3 (60%) died within 10 weeks posttransplant. This study highlights the morbidity and mortality associated with mollicute infection after lung transplantation and the need for better screening and management protocols.

Postoperative mediastinitis and sternal osteitis after cardiac surgery caused by Mycoplasma hominis: A case report

BACKGROUND

Mediastinitis and sternal osteitis are critical complications in cardiac surgery. Cases of these complications caused by Mycoplasma hominis are extremely rare.

CASE PRESENTATION

We present a case of mediastinitis and sternal osteitis caused by M. hominis infection following ascending aortic replacement surgery. Whole gene sequencing analysis suggested the genitourinary tract as the most likely source of this M. hominis infection. Successful infection control was achieved through a regimen of moxifloxacin treatment. Additionally, a notable correlation was observed between serum levels of interleukin-6 and M. hominis infection.

CONCLUSIONS

The significance of M. hominis as a potential cause of postoperative infection in cardiac surgery is still not fully recognized. Special attention should be paid to patients with bacteriologically negative infections, as M. hominis should not be disregarded, despite its rarity.

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.

Extra-urogenital infection by Mycoplasma hominis in transplant patients: two case reports and literature review

BACKGROUND

Mycoplasma hominis is a facultative anaerobic bacterium commonly present in the urogenital tract. In recent years, M. hominis has increasingly been associated with extra-urogenital tract infections, particularly in immunosuppressed patients. Detecting M. hominis in a diagnostic laboratory can be challenging due to its slow growth rate, absence of a cell wall, and the requirements of specialized media and conditions for optimal growth. Consequently, it is necessary to establish guidelines for the detection of this microorganism and to request the appropriate microbiological work-up of immunosuppressed patients.

CASE PRESENTATION

We hereby present two cases of solid organ transplant patients who developed M. hominis infection. Microscopic examination of the bronchial lavage and pleural fluid showed no microorganisms. However, upon inoculating the specimens onto routine microbiology media, the organism was successfully identified and confirmation was performed using 16S rDNA sequencing. Both patients received appropriate treatment resulting in the resolution of M. hominis infection.

CONCLUSIONS

The prompt detection of M. hominis in a clinical specimen can have a significant impact on patient care by allowing for early intervention and ultimately resulting in more favorable clinical outcomes, especially in transplant patients.

Routine Donor and Recipient Screening for Mycoplasma hominis and Ureaplasma Species in Lung Transplant Recipients

BACKGROUND

Mycoplasma hominis, Ureaplasma urealyticum, and Ureaplasma parvum may cause post-transplant infections in lung transplant recipients. We evaluated routine pretransplant screening for these Mollicutes.

METHODS

We retrospectively reviewed records of lung transplant recipients at our tri-site institution from 01/01/2015 to 11/15/2019. M. hominis and/or Ureaplasma polymerase chain reaction (PCR) was performed on pretransplant recipient urine specimens and donor bronchial swabs at the time of transplantation. Development of Mollicute infection and hyperammonemia syndrome (HS) was recorded.

RESULTS

A total of 268 patients underwent lung transplantation during the study period, of whom 105 were screened with at least 1 Mollicute PCR. Twelve (11%) screened positive; 10 donors, 1 recipient, and 1 both. Among positive donors, 3 were positive for M. hominis, 5 for U. urealyticum, and 4 for U. parvum. Preemptive therapy included doxycycline, levofloxacin, and/or azithromycin administered for 1-12 weeks. Despite therapy, 1 case of M. hominis mediastinitis and 1 case of HS associated with Ureaplasma infection occurred, both donor-derived. Of those screened before transplant, cases with positive screening were more likely (P < 0.05) to develop Mollicute infection despite treatment (2/12, 17%) than those who screened negative (1/93, 1%).

CONCLUSIONS

Pretransplant recipient urine screening had a low yield and was not correlated with post-transplant Mollicute infection, likely because most M. hominis and U. parvum/urealyticum infections in lung transplant recipients are donor-derived. Routine donor bronchus swab PCR for M. hominis, U. urealyticum, and U. parvum followed by preemptive therapy did not obviously impact the overall incidence of Mollicute infection or HS in this cohort.

Periprosthetic joint infection due to Mycoplasma hominis in a multiple sclerosis patient treated with fingolimod

Mycoplasma hominis is a commensal pathogen normally found in urogenital tract of humans and has been associated with a wide variety of extra-genitourinary infections, such as mediastinitis, bacteremia, and septic arthritis, particularly in immunocompromised patients. Here, we present a case of a 48-year-old male, who had been treated with fingolimod for relapsing multiple sclerosis and presented with fever and right-sided hip pain following total hip arthroplasty. CT scan revealed localized fluid collection in the right quadriceps femoris muscle adjacent to the joint cavity of right hip. The percutaneously aspirated fluid grew M. hominis, which was also isolated from blood culture. With diagnosis of periprosthetic joint infection, the patient underwent surgical debridement with retained prosthesis and was treated with antimicrobial agents. Infected granulation tissues excised from the hip was observed under an electron microscope, which revealed electron-dense rounded structures contained in neutrophils, consistent with Mycoplasma particles. Fingolimod, an immunomodulatory drug that acts on the sphingosine-1-phosphate receptor and prevents the egress of lymphocytes from lymph nodes, might increase host susceptibility to a systemic M. hominis infection.

Development of a RPA-CRISPR-Cas12a Assay for Rapid, Simple, and Sensitive Detection of Mycoplasma hominis

Mycoplasma hominis, which is difficult to culture and identify by ordinary methods, is one of the smallest pathogens in the human genitourinary tract causing urogenital infections. A CRISPR-Cas12a-based detection system might provide a novel application for M. hominis nucleic acid detection in molecular diagnostics. A plasmid containing the glyceraldehyde-3-phosphate dehydrogenase gene of M. hominis (ATCC_27545) as the positive control was constructed by homologous recombination. The active Cas12a protein was purified by affinity chromatography. The primers for recombinase polymerase amplification (RPA), the CRISPR RNA (crRNA), and the ratio of Cas12a to crRNA were further optimized. Finally, the sensitivity, specificity, and clinical effectiveness of the Cas12a detection system were confirmed. We successfully constructed and optimized a novel nucleic acid detection system for M. hominis based on RPA-CRISPR-Cas12a, and the whole process takes only 1 h. The limit of detection for the gap gene of M. hominis was 3 copies/μl and no cross-reactivity with other urogenital pathogens appeared. In the evaluation of 111 clinical samples, the sensitivity and specificity were both 1.000 and the area under the curve of the receiver operating characteristic was 1.000 (p < 0.001), indicating that the RPA-Cas12a-fluorescent assay was fully comparable to the traditional culture method. Finally, the RPA-Cas12a detection system can also be combined with lateral flow strips (LFS) to achieve visual detection. We successfully developed a low-cost and rapid detection method of M. hominis based on RPA-Cas12a technology. This method realized by fluorescence value readout and visual detection by LFS could be applied in population screening and resource-limited conditions.

Identification of sacrococcygeal and pelvic abscesses infected with invasive Mycoplasma hominis by MALDI‐TOF MS

Background

Methods

Results

Conclusion

Lung Abscess and Recurrent Empyema After Infection With Mycoplasma hominis: A Case Report and Review of the Literature

Mycoplasma hominis is a rarely identified cause of respiratory infection that can cause significant morbidity and mortality in immunocompromised patients. It is often missed due to the difficult detection of the organism with routine laboratory methods.

We present the case of a 63-year-old male with a history of lymphoma who was transferred to our hospital with recurrent right-sided empyema and lung abscess in the right lower lobe. Advanced microbiological analysis finally revealed infection with M hominis. Despite appropriate antibiotic treatment, prolonged drainage as well as repeated surgery, which eventually resulted in right lower bilobectomy, were necessary for clinical improvement of our patient.

Infection with M hominis may be more prevalent than previously indicated and can cause severe morbidity and mortality in thoracic surgery patients. Due to the diagnostic challenge, the appropriate antimicrobial treatment is often delayed. Inherent resistance to macrolides and inactivity of cell wall-active agents potentially complicate empiric antibiotic therapy. A review of the currently available literature enables a better understanding of the diagnostic difficulties and importance of this infection.

Defining Fluoroquinolone Resistance-Mediating Mutations from Non-Resistance Polymorphisms in Mycoplasma hominis Topoisomerases

Often dismissed as a commensal, Mycoplasma hominis is an increasingly prominent target of research due to its role in septic arthritis and organ transplant failure in immunosuppressed patients, particularly lung transplantation. As a mollicute, its highly reductive genome and structure render it refractile to most forms of treatment and growing levels of resistance to the few sources of treatment left, such as fluoroquinolones. We examined antimicrobial susceptibility (AST) to fluoroquinolones on 72 isolates and observed resistance in three (4.1%), with corresponding mutations in the quinolone resistance-determining region (QRDR) of S83L or E87G in gyrA and S81I or E85V in parC. However, there were high levels of polymorphism identified between all isolates outside of the QRDR, indicating caution for a genomics-led approach for resistance screening, particularly as we observed a further two quinolone-susceptible isolates solely containing gyrA mutation S83L. However, both isolates spontaneously developed a second spontaneous E85K parC mutation and resistance following prolonged incubation in 4 mg/L levofloxacin for an extra 24–48 h. Continued AST surveillance and investigation is required to understand how gyrA QRDR mutations predispose M. hominis to rapid spontaneous mutation and fluoroquinolone resistance, absent from other susceptible isolates. The unusually high prevalence of polymorphisms in M. hominis also warrants increased genomics’ surveillance.

Case Report: About a Case of Hyperammonemia Syndrome Following Lung Transplantation: Could Metagenomic Next-Generation Sequencing Improve the Clinical Management?

Background: Mycoplasma hominis and Ureaplasma spp. are responsible for opportunistic infections in transplant patients, sometimes causing a life-threatening hyperammonemia syndrome. Both pathogens are not identified with standard microbiology techniques, resulting in missed or delayed diagnosis. We present a clinical case that illustrates the added value that next-generation sequencing (NGS) may offer in the diagnosis of respiratory infections in immune-compromised patients. Results: A 55 years-old man with idiopathic pulmonary fibrosis underwent double lung transplantation. He received antibiotic prophylaxis with piperacillin-tazobactam and azythromycin. At day 4 post-transplantation (PTx), the patient presented an acute respiratory distress. A broncho-alveolar lavage (BAL) was performed. At day 5 PTx, the patient presented a status epilepticus due to diffuse cerebral oedema. Serum ammonia concentration was 661 μg/dL. BAL bacterial culture was negative. Because of the clinical presentation, special cultures were performed and identified 100.000 CFU/mL of M. hominis and Ureaplasma spp. and specific PCRs were positive for M. hominis and Ureaplasma parvum. Antibiotic therapy was shifted to therapeutic dose of azithromycin and doxycycline; within 48 h ammonia serum concentrations returned to normal but the coma persisted several weeks, followed by a persistent frontal lobe syndrome. A follow-up BAL was performed on day 11 Ptx. The Mycoplasma/Ureaplasma culture was negative, yet the specific PCRs remained positive. Bacterial culture found 100 CFU/mL of Staphylococcus aureus and viral culture was positive for Herpes Simplex Virus-1. These results were confirmed by metagenomic next-generation sequencing (mNGS). In the bacterial fraction, the majority of reads belonged to Corynebacterium propinquum (34.7%), S. aureus (24.1%) and Staphylococcus epidermidis (17.1%). Reads assigned to M. hominis, Ureaplasma urealyticum and parvum represented 0.71, 0.13, and 0.04% of the bacterial fraction and corresponded to 6.9 × 10³, 9.7 × 10², and 3.7 × 10² genome equivalents per mL of BAL fluid, respectively. These results are in favor of a cure of the atypical infection. Conclusions: mNGS offered added diagnostic and quantitative values compared to PCR tests, which can remain positive after resolved infections. The initiation of appropriate antibiotic therapy would have occurred earlier on, possibly resulting in a better clinical outcome if mNGS had been performed in a routine fashion.

Mycoplasma hominis hematoma infection in patient following kidney transplant

Mycoplasma species, specifically Mycoplasma hominis (M. hominis), are commonly associated with genitourinary (GU) tract infectious syndromes. However, Mycoplasma spp. can also be involved in extragenital infections, primarily in immunosuppressed patients. A 61 year old female was successfully treated with moxifloxacin and doxycycline combination therapy for an infected hematoma secondary to M. hominis following a renal transplant. Microbiology technologists noted the growth of pinpoint, translucent non-hemolytic colonies, but no organisms seen on Gram stain. These findings prompted the updated culture report of, "Growth on culture plates, gram stain suggestive of organism lacking cell wall." Empiric antimicrobials were initiated to cover both Mycoplasma spp. and Ureaplasma spp before resulting M. hominis. Initiating empiric therapy directed against Mycoplasma spp. following Gram stain results and before organism speciation may prevent a lapse in effective therapy. This is especially important as perioperative antimicrobial prophylaxis regimens consist of beta-lactam regimens directed against common GI and GU pathogens, which lack activity against Mycoplasma spp.

Tetracycline Resistance Mediated by tet(M) Has Variable Integrative Conjugative Element Composition in Mycoplasma hominis Strains Isolated in the United Kingdom from 2005 to 2015

A minimal genome and absent bacterial cell wall render Mycoplasma hominis inherently resistant to most antimicrobials except lincosamides, tetracyclines, and fluoroquinolones. Often dismissed as a commensal (except where linked to preterm birth), it causes septic arthritis in immunodeficient patients and is increasingly associated with transplant failure (particularly lung) accompanying immunosuppression. We examined antimicrobial susceptibility (AST) on strains archived from 2005 to 2015 submitted to the Public Health England reference laboratory and determined the underlying mechanism of resistance by whole-genome sequencing (WGS). Archived M. hominis strains included 32/115 from invasive infection (sepsis, cerebrospinal [CSF], peritoneal, and pleural fluid) over the 10-year period (6.4% of all samples submitted from 2010 to 2015 were positive). No clindamycin resistance was detected, while two strains were resistant to moxifloxacin and levofloxacin (resistance mutations S83L or E87G in gyrA and S81I or E84V in parC). One of these strains and 11 additional strains were tetracycline resistant, mediated by tet(M) carried within an integrative conjugative element (ICE) consistently integrated at the somatic rumA gene; however, the ICEs varied widely in 5 to 19 associated accessory genes. WGS analysis showed that tet(M)-carrying strains were not clonal, refuting previous speculation that the ICE was broken and immobile. We found tet(M)-positive and -negative strains (including the multiresistant 2015 strain) to be equally susceptible to tigecycline and josamycin; however, the British National Formulary does not include guidance for these. Continued M. hominis investigation and AST surveillance (especially immunocompromised patients) is warranted, and the limited number of therapeutics needs to be expanded in the United Kingdom.

[Clinical implications of the genus Mycoplasma]

Dentro del género Mycoplasma, las especies que tradicionalmente se han relacionado con cuadros infecciosos han sido principalmente M. pneumoniae, M. genitalium, M. hominis o U. urealyticum. Sin embargo, existen otras muchas que están implicadas y, que muchas veces, son desconocidas para los profesionales sanitarios. El objetivo de esta revisión es identificar todas las especies del género Mycoplasma que se han aislado en el hombre y determinar su participación en la patología infecciosa humana.

Unexpected Mycoplasma hominis infection in two renal transplant recipients traced back to the same donor by whole-genome sequencing

Mycoplasma hominis is a common colonizer of the lower genitourinary tract. Although its clinical relevance for causing urogenital infections in immunocompetent individuals is controversial, this bacterium has been involved in severe invasive infections in allograft recipients. In this report, we describe two cases of M. hominis infection in two young renal transplant recipients within the first month post-transplant. Although at first no epidemiological link between the two cases had been suspected, whole-genome sequencing (WGS) analysis showed that both isolates were identical, highly suggestive of an origin with the common organ donor.

Bronchial anastomosis dehiscence and stenosis caused by donor-transmitted Mycoplasma hominis infection in a lung transplant recipient: Case report and literature review

Pulmonary infection by Mycoplasma hominis (M hominis) in lung transplant (LTx) recipients is an uncommon yet potentially severe complication. Bronchial dehiscence in the context of M hominis infection has not been previously reported. In this report, we discuss a case of donor-derived M hominis infection in a LTx recipient with bilateral bronchial anastomoses dehiscence and stenosis. The infection was managed using a multidisciplinary approach: repeat surgical revision of the necrotic anastomosis; targeted antibiotic therapy with the combination of oral and inhaled fluoroquinolones, and oral doxycycline and continuous ventilatory support. Response to therapy was monitored through repeat bronchoscopy and serial quantitative PCR assays for M hominis in bronchoalveolar lavage and aspiration. The rare nature of M hominis infection after LTx, its difficult detection in conventional cultures and innate resistance to beta-lactams make diagnosis and timely treatment of this organism challenging. We recommend that transplant centers have a low threshold for screening for Mycoplasma infection, particularly in patients with unsatisfactory postoperative course and little response to broad-spectrum antimicrobial and antifungal coverage. Monitoring with PCR may help to adapt the duration of antibiotic therapy.

Mycoplasma hominis bursitis in a simultaneous pancreas-kidney transplant recipient: case report and literature review

Mycoplasma hominis can be isolated frequently from the genitourinary tract of some healthy individuals. On rare occasions, it acts as a pathogen in immunocompromised patients such as transplant recipients. Here, we describe the case of a 39-year-old man with end-stage kidney disease secondary to diabetic nephropathy who received a simultaneous pancreas-kidney transplant. He developed pancreatitis and arterial thrombosis 2 weeks post-transplant and required a pancreatectomy. His kidney allograft function remained normal. He developed severe left hip pain 2 weeks post-transplant with a trochanteric bursal effusion detected on magnetic resonance imaging. The effusion grew M. hominis. The patient was treated with 100 mg of doxycycline twice daily for 9 months with full resolution of the effusion at 4 months post-treatment. We also review all previously reported M. hominis infections in transplant recipients.

Consequences of donor-derived passengers (pathogens, cells, biological molecules and proteins) on clinical outcomes

It is recognized that donor factors contribute to lung transplant outcomes. Recent observations and studies have started to elucidate potential mechanisms behind explaining these observations. This perspective piece summarizes evolving lung transplant literature on the subject, focusing on donor "passenger" organisms, cells, hormones, and proteins transferred to the recipient. Many extrinsic and intrinsic donor features or properties have important consequences for subsequent allograft function in the recipient. Potentially, a better understanding of these features may provide useful novel therapeutic targets to enhance allograft outcomes.

An Update in Antimicrobial Therapies and Infection Prevention in Pediatric Lung Transplant Recipients

Lung transplantation can offer life-prolonging therapy to children with otherwise terminal end-stage lung disease. However, infectious complications, like those experienced by their adult counterparts, are a significant cause of morbidity and mortality. These include bacteria, viruses, and fungi that infect the patient pretransplant and those that may be acquired from the donor or by the recipient in the months to years posttransplant. An understanding of the approach to the management of each potential infecting organism is required to ensure optimal outcomes. In particular, emphasis on aggressive preoperative management of infections in pediatric patients with cystic fibrosis is important. These include multidrug-resistant Gram-negative bacteria, fungi, and Mycobacterium abscessus, the posttransplant outcome of which depends on optimal pretransplant management, including vaccination and other preventive, antibiotic-sparing strategies. Similarly, increasing the transplant donor pool to meet rising transplant demands is an issue of critical importance. Expanded-criteria donors-those at increased risk of blood-borne viruses in particular-are increasingly being considered and transplants undertaken to meet the rising demand. There is growing evidence in the adult pool that these transplants are safe and associated with comparable outcomes. Pediatric transplanters are therefore likely to be presented with increased-risk donors for their patients. Finally, numerous novel antibiotic-sparing therapeutic approaches are on the horizon to help combat infections that currently compromise transplant outcomes.

Successful treatment of Ureaplasma-induced hyperammonemia syndrome post-lung transplant

Hyperammonemia, in the absence of significant liver dysfunction, is an uncommon but often fatal occurrence following orthotopic lung transplant. Prior reports have provided evidence to support Ureaplasma species as an etiology for this syndrome. This case report describes an individual post-lung transplant, treated emperically with doxycycline along with other measures to lower ammonia levels, at the time hyperammonemia with encephalopathy was recognized. The patient clinically improved. Ureaplasma species were subsequently identified using 16S ribosomal RNA gene PCR/sequencing of pleural fluid, and by culture of bronchoalveolar (BAL) fluid. This case provides further support for empiric treatment of Ureaplasma species upon recognition of hyperammonemia syndrome post-lung transplant.

Donor-Derived Mycoplasma hominis and an Apparent Cluster of M. hominis Cases in Solid Organ Transplant Recipients

Background

Invasive and disseminated Mycoplasma hominis infections are well recognized but uncommon complications in solid organ transplant recipients. In a single center, a cluster of M. hominis infections were identified in lung transplant recipients from the same thoracic intensive care unit (ICU). We sought to determine the source(s) of these infections.

Methods

Medical records of the donor and infected transplant recipients were reviewed for clinical characteristics. Clinical specimens underwent routine processing with subculture on Mycoplasma-specific Hayflick agar. Mycoplasma hominis identification was confirmed using sequencing of the 16S ribosomal RNA gene. Mycoplasma hominis isolates were subjected to whole-genome sequencing on the Illumina NextSeq platform.

Results

Three lung transplant recipients presented with invasive M. hominis infections at multiple sites characterized by purulent infections without organisms detected by Gram staining. Each patient had a separate donor; however, pretransplant bronchoalveolar lavage fluid was only available from the donor for patient 1, which subsequently grew M. hominis. Phylo- and pangenomic analyses indicated that the isolates from the donor and the corresponding recipient (patient 1) were closely related and formed a distinct single clade. In contrast, isolates from patients 2 and 3 were unrelated and divergent from one another.

Conclusions

Mycoplasma hominis should be considered a cause of donor-derived infection. Genomic data suggest donor-to-recipient transmission of M. hominis. Additional patients co-located in the ICU were found to have genetically unrelated M. hominis isolates, excluding patient-to-patient transmission.