Catheter-related bacteremia caused by Comamonas testosteroni in a hemodialysis patient

Bacteria of Zoonotic Interest Identified on Edible Freshwater Fish Imported to Australia

Previous research has shown that freshwater edible fish imported into Australia are not compliant with Australian importation guidelines and as a result may be high risk for bacterial contamination. In the present study, the outer surface of imported freshwater fish were swabbed, cultured, confirmatory tests performed and antimicrobial patterns investigated. Channidae fish (Sp. A/n = 66) were contaminated with zoonotic Salmonella sp./Staphylococcus aureus (n = 1/66) and other bacteria implicated in cases of opportunistic human infection, these being Pseudomonas sp. (including P. mendocina and P. pseudoalcaligenes (n = 34/66)); Micrococcus sp. (n = 32/66); Comamonas testosteroni (n = 27/66) and Rhizobium radiobacter (n = 3/66). Pangasiidae fish (Species B/n = 47) were contaminated with zoonotic Vibrio fluvialis (n = 10/47); Salmonella sp. (n = 6/47) and environmental bacteria Micrococcus sp. (n = 3/47). One sample was resistant to all antimicrobials tested and is considered to be Methicillin Resistant S. aureus. Mud, natural diet, or vegetation identified in Sp. A fish/or packaging were significantly associated with the presence of Pseudomonas spp. The study also showed that visibly clean fish (Sp. B) may harbour zoonotic bacteria and that certain types of bacteria are common to fish groups, preparations, and contaminants. Further investigations are required to support the development of appropriate food safety recommendations in Australia.

An investigation of clinical characteristics and antimicrobial agent susceptibility patterns in clinical Comamonas testosteroni isolates: An increasingly prevalent nosocomial pathogen

BACKGROUND

Comamonas testosteroni is a gram-negative bacillus, known before 1987 as Pseudomonas testosteroni. Although considered as a rare pathogen, its frequency has been increasing. Data regarding its antibiotic susceptibility are insufficient. To date, forty-four cases have been reported in the literature. In this study, we identified the C. testosteroni infections observed in our hospital and evaluated their antimicrobial agent susceptibility patterns compared with cases reported in the literature.

METHODS

For the purposes of the present study, patients admitted to hospital between November 2019 and December 2020 were screened. Those with clinical and laboratory signs of infection with positive C. testosteroni growth in culture were enrolled. Clinical isolates obtained from the samples processed in accordance with standard microbiological examination procedures in our laboratory were defined by MALDI-TOF mass spectrometry with 99.9% probability as C. testosteroni.

RESULTS

C testosteroni infection was detected between November 2019 and December 2020 in eight patients in our hospital. Six of them had a bloodstream infection (BSI), one had pneumonia, and one had urinary tract infection due to C. testosteroni. Coexistence of COVID-19 was detected in four patients. Six out of the eight cases with BSI had hospital-acquired infection and all of the infections were healthcare-associated. When antimicrobial agent susceptibility results reported in the literature were evaluated in combination with the current results, ceftazidime and meropenem were found to be the most susceptible agents (96.1% and 80%, respectively).

CONCLUSIONS

The frequency of nosocomial C. testosteroni infections and resistance to antimicrobial agents are gradually increasing. While resistance to carbapenems is on the upswing, third-generation cephalosporins are still seen as suitable treatment options.

Pseudomonadota in the oral cavity: a glimpse into the environment-human nexus

The phylum Pseudomonadota is amongst the most represented in the environment, with a comparatively lower prevalence in the human oral cavity. The ubiquity of Pseudomonadota and the fact that the oral cavity is the most likely entry portal of bacteria from external sources underlie the need to better understand its occurrence in the interface environment-humans. Yet, the relevance oral Pseudomonadota is largely underexplored in the scientific literature, a gap that this review aims at addressing by making, for the first time, an overview of the diversity and ecology of Pseudomonadota in the oral cavity. The screening of scientific literature and human microbiome databases unveiled 1328 reports of Pseudomonadota in the oral cavity. Most of these belonged to the classes Beta- and Gammaproteobacteria, mainly to the families Neisseriaceae, Campylobacteriaceae, and Pasteurelaceae. Others also regularly reported include genera such as Enterobacter, Klebsiella, Acinetobacter, Escherichia, Burkholderia, or Citrobacter, whose members have high potential to acquire virulence and antibiotic resistance genes. This review provides evidence that clinically relevant environmental Pseudomonadota may colonize humans via oral cavity. The need for further investigation about Pseudomonadota at the environment-oral cavity interface and their role as vectors potentially involved in virulence and antibiotic resistance transmission is demonstrated. KEY POINTS: • Neisseriaceae, Campylobacteriaceae, and Pasteurelaceae are part of the core oral microbiome • Enterobacteriaceae, Acinetobacter, or Burkholderia are frequent in the oral microbiome • Gut dysbiosis may be associated with colonization by ubiquitous oral Pseudomonadota.

The Emergence of the Genus Comamonas as Important Opportunistic Pathogens

Comamonas spp. are non-fermenting Gram-negative bacilli. They were first discovered in 1894, and since then, twenty-four species have been characterized. The natural habitat of these bacteria is soil, wastewater/sludge, fresh water such as ponds and rivers, and the animal intestinal microbiome. They were also isolated from industrial settings, such as activated sludge and polluted soil, and from the hospital environment and clinical samples, such as urine, pus, blood, feces, and kidney. Comamonas spp. are associated with environmental bioremediation and are considered an important environmental bacterium rather than a human pathogen. However, in the 1980s, they became a concern when several human infections associated with these species were reported. Here, the Comamonas genus was examined in terms of its members, identification techniques, and pathogenicity. Seventy-seven infection cases associated with these microorganisms that have been discussed in the literature were identified and investigated in this project. All relevant information regarding year of infection, country of origin, patient information such as age, sex, underlying medical conditions if any, type of infection caused by the Comamonas species, antibiotic susceptibility testing, treatment, and outcomes for the patient were extracted from case reports. The findings suggest that even though Comamonas spp. are thought of as being of low virulence, they have caused harmful health conditions in many healthy individuals and even death in patients with underlying conditions. Antimicrobial treatment of infections associated with these species, in general, was not very difficult; however, it can become an issue in the future because some strains are already resistant to different classes of antibiotics. Therefore, these pathogens should be considered of such importance that they should be included in the hospital screening programs.

Comamonas testosteroni bacteremia: A rare unusual pathogen detected in a burned patient: Case report and literature review

Introduction and importance

Comamonas testosteroni is a rare human pathogen that is not part of the human microbiome. There are only 51 cases reported worldwide with 7 cases resulted in death.

Case presentation

We report a case of a 16-year-old boy with an extended burn complicated by catheter-related bloodstream C. testosteroni infection.

Clinical discussion

Comamonas species are usually community-acquired pathogens that are susceptible to a wide variety of antibiotics including aminoglycosides, fluoroquinolones, carbapenems, piperacillin-tazobactam, trimethoprim-sulfamethoxazole, and cephalosporins. However, in our case, we reported a nosocomial multidrug-resistant infection by C. testosteroni that responded only to colistin.

Conclusion

Reporting unusual cases of nosocomial sepsis due to rare multidrug-resistant pathogens is detrimental. As it sheds light on how virulent nosocomial infections are becoming, and can be very alarming to other practitioners and clinical microbiologists, in order to achieve a better awareness of the importance of controlled antibiotics use.

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Comamonas testosteroni is a rare human pathogen that is not part of the human microbiome, and is rarely recognized as a human pathogen.

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The majority of C.testosteroni infections are community-acquired rather than nosocomial. Most of the previously reported patients were immunodeficient (burn patient in our case).

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Till now, there are 51 cases reported (52 if our case is published) which most of these are due to intra-abdominal source.

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Comamonas species are usually susceptible to a wide spectrum of antibiotics. However, we report a nosocomial infection by C. testosterone which was sensitive only to colistin.

Bacteremia caused by Comamonas testosteroni an unusual pathogen

Comamonas species are rare isolates in microbiology laboratories and have been infrequently reported as an infectious agent in routine clinical practice. They have a wide range of natural habitats including water, soil, and plants as well as from some hospital devices, such as intravenous lines and the reservoir water in the humidifiers of respiratory therapy equipment. Comamonas testosteroni is rarely recognized as a human pathogen. In spite of its uncommon human pathogenesis, there are few reports where it was reported as an aggressive opportunistic pathogen, and that was mostly related to Testosterone species. Herewith, we are reporting this pathogen from the blood of an immunocompetent female. The aim of this case report is to alert clinicians and laboratory physicians for the potential diagnosis and clinical approach of bloodstream infections caused by such unusual pathogens. This is the first documented case of bacteremia caused by C. testosteroni from India.

The characterization of a short chain dehydrogenase/reductase (SDRx) in Comamonas testosteroni

C. testosteroni is a research topic that can degrade steroid hormones into water and carbon dioxide through a series of enzymes in the body. Short-chain dehydrogenase (SDR) are a class of NAD (P) H-dependent oxidoreductases in C. testosteroni. Its main function is catalyzing the redox of the hydroxyl/ketone group of the hormone. In this paper, a SDR gene(SDRx) is cloned from C. testosteroni ATCC11996 and expressed. The polyclonal antibody was prepared and the SDRx gene knocked out by homologous recombination. Wild type and mutant C. testosteroni induced by testosterone, estradiol, estrone and estriol. The growth curves of the bacteria were measured by spectrophotometer. ELISA established the expression of SDRx protein, and high-performance liquid chromatography(HPLC) detected the contents of various hormones. The results show that the growth of wild type was faster than mutant type induced by testosterone. The concentration of SDRx is 0.318 mg/ml under testosterone induction. It has a great change in steroid hormones residue in culture medium measured by HPLC: Testosterone residue in the mutant type group was 42.4 % more than the wild type in culture medium. The same thing happens with induced by estrone. In summary, this SDRx gene involved in the degradation of testosterone and estradiol, and effects the growth of C. testosteroni.

Comamonas kerstersii bacteremia in a patient with acute perforated appendicitis: A rare case report

RATIONALE

Comamonas species are rarely associated with human infections. Recent reports found that Comamonas kerstersii was associated with severe diseases such as abdominal infection and bacteremia. However, C. kerstersii maybe be confused with Comamonas testosteroni using the automatic bacterial identification systems currently available.

PATIENT CONCERNS

A 31-year-old man who had onset of left upper abdominal pain developed clinical manifestations of right lower abdominal pain and classic migration of pain at the temperature of 39°C. The positive strain of aerobic and anaerobic bottles of blood cultures was identified.

DIAGNOSES

The patient was diagnosed as acute peritonitis and perforated appendix with abdominal abscess.

INTERVENTIONS

The bacterium was identified by routine methods, MALDI-TOF-MS and PCR amplification of the 16S rRNA. The patient was treated with exploratory laparotomy, appendectomy, tube drainage, and prescribing antibiotic treatment.

OUTCOMES

The patients were discharged with complete recovery. The organisms were confirmed as C. kerstersii by MALDI-TOF-MS and a combination of the other results.

LESSONS

Our findings suggest that C. kerstersii infection occurs most often in association with perforated appendix and bacteremia. We presume that C. kerstersii is an opportunistic pathogen or commensal with the digestive tract and appendix bacteria.

Unusual presentations of Comamonas kerstersii infection

The association of Comamonas kerstersii with peritonitis resulting from the presence of perforated appendix has previously been described by our research team. In the present study, we describe the isolation of this microorganism from two forms of unusual presentations of C. kerstersii infection not previously described in the literature: localized intra-abdominal infection (psoas abscess) and pelvic peritonitis.

Comamonas testosteroni-associated peritonitis in a pediatric peritoneal dialysis patient

Comamonas testosteroni (C. testosteroni) has been rarely observed as an infectious agent in clinical practice. Few reports described its potential pathogenicity in bloodstream and abdominal infections. Here, we report our experience in the treatment of a C. testosteroni-associated peritonitis in a four-year-old girl receiving chronic peritoneal dialysis (PD). The organism was shown to be highly susceptible to appropriate antibiotic therapy. Infection responded promptly and the patient was managed conservatively without withdrawal from PD.

High correlation between genotypes and phenotypes of environmental bacteria Comamonas testosteroni strains

BACKGROUND

Members of Comamonas testosteroni are environmental microorganisms that are usually found in polluted environment samples. They utilize steroids and aromatic compounds but rarely sugars, and show resistance to multiple heavy metals and multiple drugs. However, comprehensive genomic analysis among the C. testosteroni strains is lacked.

RESULTS

To understand the genome bases of the features of C. testosteroni, we sequenced 10 strains of this species and analyzed them together with other related published genome sequences. The results revealed that: 1) the strains of C. testosteroni have genome sizes ranging from 5.1 to 6.0 Mb and G + C contents ranging from 61.1% to 61.8%. The pan-genome contained 10,165 gene families and the core genome contained 3,599 gene families. Heap's law analysis indicated that the pan-genome of C. testosteroni may be open (α = 0.639); 2) by analyzing 31 phenotypes of 11 available C. testosteroni strains, 99.4% of the genotypes (putative genes) were found to be correlated to the phenotypes, indicating a high correlation between phenotypes and genotypes; 3) gene clusters for nitrate reduction, steroids degradation and metal and multi-drug resistance were found and were highly conserved among all the genomes of this species; 4) the genome similarity of C. testosteroni may be related to the geographical distances.

CONCLUSIONS

This work provided an overview on the genomes of C. testosteroni and new genome resources that would accelerate the further investigations of this species. Importantly, this work focused on the analysis of potential genetic determinants for the typical characters and found high correlation between the phenotypes and their corresponding genotypes.

Polymicrobial Bacteremia Involving Comamonas testosteroni

Comamonas spp. are uncommon isolates in microbiology laboratories and have been rarely observed as an infectious agent in clinical practice. They have widespread environmental distribution and have been isolated from water, soil, and plants as well as from some hospital devices such as intravenous catheters and water contained in humidifier reservoirs used in respiratory treatment. The genus Comamonas originally contained the following species: acidovorans, testosteroni, kerstersii, terrigena, denitrificans, and nitrativorans. It now contains 17 species, while acidovorans spp. have been reclassified as Delftia acidovorans. In spite of its uncommon human pathogenesis, there are few reports on the aggressive manner of it as an opportunistic pathogen, mostly related to testosteroni spp. We present a case of polymicrobial bacteremia involving Comamonas testosteroni. The aim of this case report is to alert clinicians to the potential diagnosis of bloodstream infections caused by uncommon pathogens.

Bacteremia caused by Comamonas kerstersii in a patient with diverticulosis

We report for the first time a case of bacteremia caused by Comamonas kerstersii in a 65-year-old patient with sign of diverticulosis. In addition, we review the isolation of Comamonas sp. and related organisms in our hospital over 25 years.

Intra-abdominal infections due to Comamonas kerstersii

Herein, we report four cases of Comamonas kerstersii intra-abdominal infections representing the first report of human infections caused by this Comamonas species. In addition, our work demonstrates the association of C. kerstersii with peritonitis secondary to appendix rupture.

Description of Acidovorax wautersii sp. nov. to accommodate clinical isolates and an environmental isolate, most closely related to Acidovorax avenae

Three Gram-negative strains, NF 1078(T), NF 1598 and NF 1715, were isolated from clinical (two) and environmental (one) samples, respectively. Sequence analysis of the 16S rRNA genes revealed similarity of 100% among the three strains and next highest similarity to the type strain of Acidovorax avenae (98.16%). The three strains were able to acidify lactose and rhamnose on low peptone phenol red agar and to alkalinize citrate on Simmons' agar and were negative for nitrate reduction. The DNA G+C content of strain NF 1078(T) was 67.1 mol%. The level of DNA-DNA relatedness between this strain and the type strains of A. avenae (ATCC 19860(T), LMG 2117(T)) was 29%. Based on these phylogenetic, phenotypic and genotypic analyses, the three strains could be distinguished clearly from all other recognized Acidovorax species and should be classified as representatives of a novel species of the genus Acidovorax, for which the name Acidovorax wautersii sp. nov. is proposed. The type strain is NF 1078(T) (=LMG 26971(T)=CCUG 62584(T)).