PCR methods in clinical investigations of human ureaplasmas: a minireview

Next-generation sequencing-based detection of Ureaplasma in the gastric fluid of neonates with respiratory distress and chorioamnionitis

BACKGROUND

Respiratory distress is common in neonates admitted to neonatal intensive care units. Additionally, infectious diseases such as intrauterine infections or vertical transmission are important underlying causes of respiratory failure. However, pathogens often cannot be identified in neonates, and there are many cases in which antibacterial drugs are empirically administered. Next-generation sequencing (NGS) is advantageous in that it can detect trace amounts of bacteria that cannot be detected by culturing or bacteria that are difficult to cultivate. However, there are few reports on the diagnosis of infectious diseases using NGS in the neonatal field, especially those targeting respiratory distress.

OBJECTIVE

The purpose of our study was to investigate the microorganisms associated with neonatal respiratory distress and to determine whether less invasive collection specimens such as plasma and gastric fluid are useful.

METHODS

Neonates were prospectively recruited between January and August 2020 from Nagoya University Hospital. The inclusion criteria were as follows: 1) admission to the neonatal intensive care unit; 2) respiratory distress presentation within 48 h of birth; and 3) suspected infection, collection of blood culture, and administration of antibiotics. Plasma samples and blood cultures were simultaneously collected. Gastric fluid samples were also collected if the patient was not started on enteral nutrition. Information on the patients and their mothers were collected from the medical records. DNA was extracted from 140 µL of plasma and gastric fluid samples. DNA sequencing libraries were prepared, and their quality was analyzed. DNA libraries were sequenced using high-throughput NGS. The NGS data of plasma and gastric fluid samples were analyzed using the metagenomic pipeline PATHDET, which calculated the number of reads assigned to microorganisms and their relative abundance. Putative pathogens were listed.

RESULTS

Overall, 30 plasma samples and 25 gastric fluid samples from 30 neonates were analyzed. Microorganism-derived reads of gastric fluid samples were significantly higher than those of plasma samples. Transient tachypnea of the newborn was the most common cause of respiratory distress with 13 cases (43%), followed by respiratory distress syndrome with 7 cases (23%). There were 8 cases (29%) of chorioamnionitis and 7 cases (25%) of funisitis pathologically diagnosed. All blood cultures were negative, and only two gastric fluid cultures were positive for group B Streptococcus (Patient 15) and Candida albicans (Patient 24). Putative pathogens that met the positive criteria for PATHET were detected in four gastric fluid samples, one of which was group B Streptococcus from Patient 15. In the gastric fluid sample of Patient 24, Candida albicans were detected by NGS but did not meet the positive criteria for PATHDET. Cluster analysis of the plasma samples divided them into two study groups, and the indicator genera of each cluster (Phormidium or Toxoplasma) are shown in Figure 1. Clinical findings did not show any significant differences between the two groups. Cluster analysis of the gastric fluid samples divided them into three study groups, and the indicator genera of each cluster (Ureaplasma, Nostoc, and Streptococcus) are shown in Figure 2. The incidence rate of chorioamnionitis was significantly higher in Ureaplasma group than in the other two groups.

CONCLUSION

Gastric fluid may be useful for assessing neonatal patients with respiratory distress. To the best of our knowledge, this was the first study to reveal that the presence of Ureaplasma in the gastric fluid of neonates with respiratory distress was associated with chorioamnionitis. The early diagnosis of intra-amniotic infections using gastric fluid and its treatment may change the treatment strategy for neonatal respiratory distress. Screening for Ureaplasma in neonates with respiratory distress may reduce the need for empirical antibiotic administration. Further research is required to confirm these findings.

Dual Ureaplasma parvum arthritis: a case report of U. parvum septic arthritis following contralateral reactive arthritis in an immunosuppressed patient

Background

Ureaplasma parvum is usually part of the normal genital flora. Rarely can it cause invasive infections such as genitourinary infections, septic arthritis, or meningitis.

Case presentation

Here we present the first description of chronic ureterocystitis in a 56-year-old immunocompromised patient, complicated first by reactive arthritis and secondarily by contralateral septic arthritis due to U. parvum infection. U. parvum was detected in synovial fluid and in a urine sample. Treatment consisted of double-J stenting and targeted antibiotic therapy. Evolution showed resolution of urinary symptoms and clinical improvement of arthritis despite functional sequelae.

Conclusions

Given the high prevalence of U. parvum colonisation, this diagnosis should remain a diagnosis of exclusion. However, because of the difficulty in detecting this microorganism, it should be considered in unexplained subacute urethritis or arthritis, including reactive arthritis, especially in immunosuppressed patients. Real-time PCR positivity in the absence of a differential diagnosis should not be overlooked.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-06733-0.

Serological investigation of Ureaplasma urealyticum in Korean preterm infants

Purpose

Ureaplasma colonization is related with perinatal complications in preterm infants. Little is known about the difference in virulence among various Ureaplasma urealyticum serovars. The aim of this study was to determine U. urealyticum serovars of preterm infants in order to assess whether any of the serovars were associated with bronchopulmonary dysplasia (BPD).

Methods

Three hundred forty-four preterm infants with a gestational age less than 34 weeks admitted to Gangnam Severance Hospital neonatal intensive care unit from July 2011 to December 2012 were included in this study. Tracheal and gastric aspirations were conducted on infants to confirm Ureaplasma colonization. Ureaplasma colonization was confirmed in 9% of infants, of these, serovars were determined by real-time polymerase chain reaction.

Results

A total of 31 infants (gestational age, 29.3±3.1 weeks; birth weight, 1,170±790 g) were U. urealyticum positive. The Ureaplasma positive group treated for more days with oxygen and ventilation than the negative group (P<0.05). Histologic chorioamnionitis and moderate to severe BPD were more frequent in the Ureaplasma positive group than in the negative group (P<0.05). U. urealyticum isolates were either found to be a mixture of multiple serovars (32%), serovar 9 alone or combined with other serovars (39%), serovar 11 (26%), 2 (13%), 8 (10%), 10 (13%), and 13 (25%). No individual serovars were significantly associated with moderate to severe BPD and chorioamnionitis.

Conclusion

This is the first study to describe the distribution of U. urealyticum serovars from Korean preterm infants. Ureaplasma-colonized infants showed higher incidence of BPD and chorioamnionitis.

Ureaplasma urealyticum is associated with nongonococcal urethritis among men with fewer lifetime sexual partners: a case-control study

BACKGROUND

Ureaplasmas have been inconsistently associated with nongonococcal urethritis (NGU). We evaluated the association of the newly differentiated species Ureaplasma urealyticum (UU) and Ureaplasma parvum (UP) with NGU using 2 separate control groups.

METHODS

Case patients were men who attended a sexually transmitted disease (STD) clinic in Seattle, Washington, during the period 2007-2009 with NGU (defined as visible urethral discharge and/or ≥5 polymorphonuclear neutrophils per high-powered field; n = 329). Control subjects were STD clinic attendees (n = 191) and emergency department (ED) attendees (n = 193) without NGU. Polymerase chain reaction assays detected UU and UP in ureaplasma culture-positive urine. Multivariable logistic regression was used to assess the associations of UU and UP with NGU.

RESULTS

UU was only marginally associated with NGU in aggregate multivariable analyses, irrespective of control group (adjusted odds ratio [aOR](STD-control), 1.6 [95% confidence interval {CI}, 0.9-2.8]; aOR(ED-control), 1.7 [95% CI, 0.97-3.0]). This association was significantly stronger when analyses were restricted to men with fewer lifetime sex partners (<10 vaginal partners: aOR(STD-control), 2.9 [95% CI, 1.2-6.7]; aOR(ED-control), 3.2 [95% CI, 1.3-7.6]; <5 vaginal partners: aOR(STD-control), 6.2 [95% CI, 1.8-21.0]; aOR(ED-control), 5.2 [95% CI, 1.3-20.2]). UP was not positively associated with NGU overall or among subgroups.

CONCLUSIONS

The absence of an association of UU with NGU among men with more lifetime sex partners suggests that adaptive immunity may attenuate the clinical manifestation of UU infection. Similar relationships were not observed with UP, which suggests that it is not a urethral pathogen.

In utero exposure to Ureaplasma spp. is associated with increased rate of bronchopulmonary dysplasia and intraventricular hemorrhage in preterm infants

AIMS

We determined the association between short-term neonatal morbidities, such as bronchopulmonary dysplasia (BPD) and intraventricular hemorrhage (IVH), and Ureaplasma spp. in amniotic fluid, placental and amniotic membrane of preterm infants.

METHODS

This study enrolled 257 patients who were born by cesarean section at <34 weeks' gestation. Patients were divided into two groups according to detection of Ureaplasma spp. by culture-based and/or polymerase chain reaction (PCR) techniques.

RESULTS

Significant differences were observed between both groups for all IVH (P=0.032) and IVH grades III or IV (P=0.013), as wells as for BPD [odds ratio (OR) 5.46, 95% confidence interval (CI) 2.02-14.77], oxygen requirement at 28 days postnatal age (OR 1.93, 95% CI 1.00-3.70), and for death between 28 days and 36 postmenstrual weeks or BPD (OR 4.20, 95% CI 1.77-9.96). Ureaplasma spp. was a significant predictor (P<0.001) of BPD after correcting for birth weight (P=0.003) and positive pressure ventilation (P=0.001).

CONCLUSIONS

In our study population Ureaplasma spp. was associated with BPD and IVH in preterm infants even after adjustment for multiple risk factors.

Ureaplasma infections in pre-term infants: Recent information regarding the role of Ureaplasma species as neonatal pathogens

Although numerous clinical observational studies have been conducted over a period of over 30 years, the clinical significance of Ureaplasma infection is still under debate. The Ureaplasma speices. is a commensal in the female genital tract and considered to have of low virulence; however, Ureaplasma colonization has been associated with infertility, stillbirth, preterm delivery, histologic chorioamnionitis, and neonatal morbidities, including congenital pneumonia, meningitis, bronchopulmonary dysplasia, and perinatal death. Recently, Ureaplasma was subdivided into 2 separate species and 14 serovars. Ureaplasma parvum is known as biovar 1 and contains serovars 1, 3, 6, and 14, and Ureaplasma urealyticum (biovar 2) contains the remaining serovars (2, 4, 5, and 7-13). The existence of differences in pathogenicities of these 14 serovars and 2 biovars is controversial. Although macrolides are the only antimicrobial agents currently available for use in neonatal ureaplasmal infections, in the current clinical field, it is difficult to make decisions regarding which antibiotics should be used. Future investigations involving large, multicenter, randomized, controlled studies are needed before proper recommendations can be made for clinical practice.

Detection of ureaplasma DNA in endotracheal samples is associated with bronchopulmonary dysplasia after adjustment for multiple risk factors

Microorganisms are hypothesized to contribute to the pathogenesis of bronchopulmonary dysplasia (BPD) in very low birth weight (VLBW) infants. This hypothesis remains controversial. We sought to determine whether endotracheal colonization with Ureaplasma sp., adenovirus, or Chlamydia sp. increases the risk of BPD. Intubated VLBW infants were included. Polymerase chain reaction (PCR) analysis was used to detect Ureaplasma sp., adenovirus, and Chlamydia sp. The outcome measure was BPD or death due to lung disease. Detection of microorganisms was compared between subjects with and without BPD. Logistic regression was used to control for covariates. Of 139 subjects, 33 (25%) screened positive for Ureaplasma sp., 22 of 136 (16%) were positive for adenovirus; eight of 133 (6%) were positive for Chlamydia sp. At 36 wk postmenstrual age, 14 patients had died, 68 (57%) had BPD. Detection of Ureaplasma sp. was associated with BPD or death (p < 0.001); adenovirus (p = 0.52) and Chlamydia sp. (p = 0.33) were not. Controlling confounding factors, the odds ratio for Ureaplasma sp. and BPD or death was 4.2 (95% CI 1.03, 17). In our population, detection of Ureaplasma sp., but not adenovirus or Chlamydia sp. was associated with BPD or death due to lung disease.

Ureaplasma infection and neonatal lung disease

Infection with the ureaplasmas may occur in utero or perinatally in prematurely born infants. For some infants, infection with these organisms triggers a vigorous pro-inflammatory response in the lungs and increases the risk of developing bronchopulmonary dysplasia (BPD). At present, there is insufficient evidence from clinical trials to determine whether antibiotic treatment of Ureaplasma has any influence on the development of BPD and its comorbidities. Future investigation in the context of well-designed, adequately powered controlled clinical trials should focus on determining whether treatment of ureaplasmal infection lessens lung inflammation, decreases rates of BPD, and improves long-term, neurodevelopmental outcome.

Immunomodulation by SanPharma Fungal Metabolic Products

OBJECTIVE

In the present study, a series of fungal metabolite products from SanPharma (Dohren, Germany) were tested for effects on human peripheral blood leukocytes in vitro using standard immunologic methods.

BACKGROUND

Therapeutic strategies used in German biological medicine often include treatment (oral, nasal, rectal, topical, or injection) with fungal or bacterial products, also known as "isopathic remedies," of which some are limited to metabolic products, whereas others include microbial cell lysates and cell wall fragments as well. The SanPharma products are based on metabolites, and do not contain microbial cell wall compounds.

METHODS

Activation of natural killer (NK) cells was evaluated by cell surface immunostaining using CD3, CD56, CD69, and CD25 monoclonal antibodies. Production of interferon-gamma was evaluated by enzyme-linked immunoabsorbent assay (ELISA) on supernatants collected after 5 days' culture of peripheral blood mononuclear cells (PBMC). Direct mitogenic effect was assessed using the lipophilic membrane dye PHK26 (Sigma-Aldrich, St. Louis, MO) in a fluorescence-based proliferation assay, in which fluorescence intensity is reduced upon cell divisions. Cell viability upon exposure to fungal metabolites was assessed using propidium iodide staining and flow cytometry.

RESULTS

All fungal metabolite products specifically induced the expression of the CD69 marker on human CD3-negative, CD56-positive NK cells, but not CD3-positive T cells, in vitro, as shown by the induction of the CD69 marker on up to 50% of NK cells after 18 hours' culture with metabolites. Only one of the five metabolite products, Roqueforti, induced cyclooxygenase-2 (COX-2), indicating that nuclear factor-kappaB (NFkappaB)-mediated signaling may not have been involved in the NK activation by the other four products. The Notatum product reduced baseline levels of COX-2, indicating an anti-inflammatory effect. No evidence of toxic or mitogenic effects was found.

CONCLUSIONS

The fungal metabolite products from SanPharma specifically activate human NK cells in vitro.

Critical appraisal of the role of Ureaplasma in the development of bronchopulmonary dysplasia with metaanalytic techniques

BACKGROUND

Controversy exists over whether or not Ureaplasma colonization or infection of the respiratory tract contributes to the development of bronchopulmonary dysplasia (BPD). Because BPD is a major cause of morbidity and mortality in preterm infants and a potential therapeutic intervention with antimicrobials is possible, we sought to evaluate and critique the current medical literature and to document the reported association between Ureaplasma and BPD.

METHODS

We analyzed all peer-reviewed articles and previous reviews including cross-references that reported Ureaplasma respiratory tract colonization or infection and development of BPD in neonates published from January 1966 to December 2004. Inclusion criteria included a cohort limited to all neonatal intensive care unit admissions or all colonized infants, articles that did not define a numerator and a denominator for BPD and Ureaplasma or that included patients from other reports were excluded from the analysis. We evaluated BPD at 28 postnatal days (BPD28) or 36 weeks post-menstrual age (BPD36).

RESULTS

Twenty-three studies with an aggregate of 2216 infants reported BPD28, and 8 studies with 751 infants reported BPD36. Although there was significant association between Ureaplasma colonization and both BPD28 and BPD36, there was substantial heterogeneity (Q test statistic, P < 0.01). We therefore focused on describing the study characteristics associated with an increased relative proportion of BPD. The greatest contribution to effect was from the studies enrolling fewer than 100 infants.

CONCLUSION

Ureaplasma colonization is associated with higher reported rates of BPD, but the greatest reported effect is seen in small studies; reporting bias may be partially responsible for this effect.

Successful Treatment of Postvenereal Reactive Arthritis With Synovectomy and 3 Months’ Azithromycin

BACKGROUND

The effects of antibiotic therapy on the course of postvenereal reactive arthritis have not yet been elucidated.

OBJECTIVE

The objective of this study was to observe the clinical course and outcome of synovectomy and 3 months of azithromycin therapy in patients with reactive arthritis and previously diagnosed triggering bacteria.

METHODS

We performed an open, prospective study on 20 (14 male/6 female) patients with postvenereal reactive knee arthritis, aged 36.7 +/- 14.8 years, and with 16.5 +/- 20.4 months' duration of the disease. Detection of bacteria triggers was done by polymerase chain reaction, isolation and identification, and electron microscopy. Synovectomy was performed in all patients at entry into the study. Azithromycin was given at a dose of 500 mg per day for 5 days, and then 500 mg twice a week, during a 3-month period. Patients without remission were treated with combined antibiotic therapy using a macrolide, quinolone, and tetracycline for the next 4 months. Outcome evaluations of therapeutic efficacy and azithromycin safety were done after 1 and 3 months and 2 years of follow up.

RESULTS

Remission, defined by the absence of joint swelling and tenderness, and extraarticular signs, was reached after 3 months in 15 of 20 (75.0%) patients (P = 0.025). Of 5 patients with persistent knee arthritis, remission was achieved with combined antibiotic therapy in 4. Visual analog scale scores (P < 0.01), the number of patients (P = 0.002), and the number of samples (P = 0.01) with a positive finding of bacteria or their DNA were significantly lower after 3 months of therapy. During the azithromycin therapy, there were no significant adverse effects.

CONCLUSIONS

These patients with reactive arthritis did extremely well on the regimen described. In our study group, the number of patients and the number of samples with positive findings of bacteria or their DNA were lower after the antibiotic treatment combined with surgery, although not all bacteria were eradicated. Adverse effects of prolonged azithromycin administration were insignificant. This open treatment approach is recommended but does need a study with controls.

Mycoplasmas and ureaplasmas as neonatal pathogens

The genital mycoplasmas represent a complex and unique group of microorganisms that have been associated with a wide array of infectious diseases in adults and infants. The lack of conclusive knowledge regarding the pathogenic potential of Mycoplasma and Ureaplasma spp. in many conditions is due to a general unfamiliarity of physicians and microbiology laboratories with their fastidious growth requirements, leading to difficulty in their detection; their high prevalence in healthy persons; the poor design of research studies attempting to base association with disease on the mere presence of the organisms in the lower urogenital tract; the failure to consider multifactorial aspects of diseases; and considering these genital mycoplasmas only as a last resort. The situation is now changing because of a greater appreciation of the genital mycoplasmas as perinatal pathogens and improvements in laboratory detection, particularly with regard to the development of powerful molecular nucleic acid amplification tests. This review summarizes the epidemiology of genital mycoplasmas as causes of neonatal infections and premature birth; evidence linking ureaplasmas with bronchopulmonary dysplasia; recent changes in the taxonomy of the genus Ureaplasma; the neonatal host response to mycoplasma and ureaplasma infections; advances in laboratory detection, including molecular methods; and therapeutic considerations for treatment of systemic diseases.