Brain abscess caused by Streptomyces infection following penetration trauma: case report and results of susceptibility analysis of 92 isolates of Streptomyces species submitted to the CDC from 2000 to 2004

Streptomyces albireticuli lung infection managed as a pulmonary air cyst: a case report and literature review

Streptomyces, the largest genus in the Streptomycetaceae family and a prolific producer of antibacterial drugs, is a saprophytic soil organism that rarely causes invasive infections. Here we report a case of necrotic pneumonia caused by Streptomyces albireticuli in a 75-year-old man who presented with progressive chest tightness and dyspnea. Streptomyces albireticuli was isolated from his bronchoalveolar lavage fluid and identified through whole-genome sequencing (WGS) and phylogenetic analysis. The patient responded satisfactorily to clarithromycin therapy. The findings of this study may enhance our vigilance in identifying visceral infections caused by Streptomyces.

Evaluation and comparison of antibiotic susceptibility profiles of Streptomyces spp. from clinical specimens revealed common and region-dependent resistance patterns

Notwithstanding the fact that streptomycetes are overlooked in clinical laboratories, studies describing their occurrence in disease and potential pathogenicity are emerging. Information on their species diversity in clinical specimens, aetiology and appropriate therapeutic treatment is scarce. We identified and evaluated the antibiotic susceptibility profile of 84 Streptomyces clinical isolates from the Czech Republic. In the absence of appropriate disk diffusion (DD) breakpoints for antibiotic susceptibility testing (AST) of Streptomyces spp., we determined DD breakpoints by correlation with the broth microdilution method and by the distribution of zone diameters among isolates. Correlation accuracy was high for 9 antibiotics, leading to the establishment of the most valid DD breakpoints for Streptomyces antibiotic susceptibility evaluation so far. Clinical strains belonged to 17 different phylotypes dominated by a cluster of strains sharing the same percentage of 16S rRNA gene sequence identity with more than one species (S. albidoflavus group, S. hydrogenans, S. resistomycificus, S. griseochromogenes; 70% of isolates). AST results showed that Streptomyces exhibited intrinsic resistance to penicillin, general susceptibility to amikacin, gentamycin, vancomycin and linezolid, and high percentage of susceptibility to tetracyclines and clarithromycin. For the remaining antibiotics, AST showed inter- and intra-species variations when compared to available literature (erythromycin, trimethoprim-sulfamethoxazole), indicating a region-dependent rather than species-specific patterns.

Identification of Streptomyces spp. in a clinical sample: always contamination? Results of a French Retrospective Study

Background

Streptomyces are environmental Gram-positive bacilli that can cause ubiquitous mycetoma and, more rarely, invasive infections. We describe the clinical relevance of Streptomyces spp. identified in human samples and characteristics of patients with invasive Streptomyces infections.

Methods

We conducted a retrospective (2006-2017) study of Streptomyces isolates identified in clinical samples in French microbiology laboratories. Streptomyces genus was confirmed by a specific 16S rRNA PCR and antibiotic susceptibility testing was performed by disk diffusion and trimethoprim-sulfamethoxazole MIC (E-test) if resistance was suspected. Patient characteristics, treatment and outcomes were collected. Invasive infection was defined as a positive culture from a sterile site with signs of infection but without cutaneous inoculation.

Results

Of 137 Streptomyces isolates, all were susceptible to amikacin (113/113) and linezolid (112/112) and 92.9% to imipenem (105/113). Using disk diffusion, 50.9% (57/112) of isolates were susceptible to trimethoprim-sulfamethoxazole but most of apparently-resistant isolates (25/36, 69.4%) tested by E-test were ultimately classified as susceptible. Clinical data were obtained for 63/137 (45.9%) isolates: 30 (47.6%) invasive infections, 8 (12.7%) primary cutaneous infections, 22 (34.9%) contaminations, 3 (4.7%) respiratory colonization. Patients with invasive infection were more frequently receiving corticosteroids than patients without invasive infection (11/30, 36.7% vs 2/25, 8.0%, P = 0.03) and at 6-months follow-up, 14 of them were cured, three had relapsed, four were dead and nine were lost to follow-up.

Conclusions

Half of the clinical samples that grew Streptomyces were from patients with invasive infection. In that case, antimicrobial therapy should include one or two antibiotics among linezolid, amikacin or imipenem.

Exploring the patient-microbiome interaction patterns for pan-cancer

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Cancer subtype-specific sets of microbiomes, making pan-cancer heterogeneity at the microbial level.

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Approximately 60% of the untreated cancer patients have experienced microbial composition changes in their tumor tissues.

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Colorectal cancer (CRC) was largely composed of two subtypes (S4 and S6) driven by different microbial profiles.

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The identified seven pan-cancer subtypes with 424 subtype-specific microbial signatures will help us find new therapeutic targets and better treatment strategies for cancer patients.

Microbes play important roles in human health and disease. Immunocompromised cancer patients are more vulnerable to getting microbial infections. Regions of hypoxia and acidic tumor microenvironment shape the microbial community diversity and abundance. Each cancer has its own microbiome, making cancer-specific sets of microbiomes. High-throughput profiling technologies provide a culture-free approach for microbial profiling in tumor samples. Microbial compositional data was extracted and examined from the TCGA unmapped transcriptome data. Biclustering, correlation, and statistical analyses were performed to determine the seven patient-microbe interaction patterns. These two-dimensional patterns consist of a group of microbial species that show significant over-representation over the 7 pan-cancer subtypes (S1-S7), respectively. Approximately 60% of the untreated cancer patients have experienced tissue microbial composition and functional changes between subtypes and normal controls. Among these changes, subtype S5 had loss of microbial diversity as well as impaired immune functions. S1, S2, and S3 had been enriched with microbial signatures derived from the Gammaproteobacteria, Actinobacteria and Betaproteobacteria, respectively. Colorectal cancer (CRC) was largely composed of two subtypes, namely S4 and S6, driven by different microbial profiles. S4 patients had increased microbial load, and were enriched with CRC-related oncogenic pathways. S6 CRC together with other cancer patients, making up almost 40% of all cases were classified into the S6 subtype, which not only resembled the normal control’s microbiota but also retained their original “normal-like” functions. Lastly, the S7 was a rare and understudied subtype. Our study investigated the pan-cancer heterogeneity at the microbial level. The identified seven pan-cancer subtypes with 424 subtype-specific microbial signatures will help us find new therapeutic targets and better treatment strategies for cancer patients.

Chronic suppurative otitis media due to Streptomyces cacaoi, the second case report in human infection

Background

Streptomyces cacaoi, Gram-positive, branched, filamentous bacillus forms without fragmentation, are saprophytic soil organisms rarely known to cause invasive infections other than mycetoma. Here we describe a case of chronic suppurative otitis media caused by Streptomyces cacaoi in a patient with hyperlipidemia in China.

Case presentation

A 62-year-old female patient with hyperlipidemia suffered chronic suppurative otitis media caused by Streptomyces cacaoi. She had a favorable outcome with a 4-week course of ofloxacin ear drops.

Conclusions

Streptomyces cacaoi is rarely reported to cause human infection. The introduction of molecular techniques improves the ability to identify rare species such as Streptomyces considerably. We report the case improve our ability to identify this pathogen and expand the range of known bacterial causes of human infection.

Community-acquired bacteremic Streptomyces atratus pneumonia in animmunocompetent adult: a case report

INTRODUCTION

Streptomyces spp. are aerobic, Gram-positive bacteria of the order Actinomycetales, known for their ability to produce antimicrobial molecules such as streptomycin. Pneumonia due to Streptomyces is considered to be rare and limited to immunocompromised patients. Streptomyces spp. are only rarely associated with invasive systemic infections. To our knowledge, we report the first documented case of community-acquired Streptomyces atratus bacteremic pneumonia in an immunocompetent patient.

CASE PRESENTATION

We describe a case of Streptomyces atratus bacteremic pneumonia in an otherwise healthy, 77-year-old Spanish man. Streptomyces identified by 16S ribosomal RNA sequencing grew in multiple blood cultures and bronchoalveolar lavage cultures. The infection resolved completely after treatment with imipenem and amoxicillin/clavulanic acid for 2 months.

CONCLUSIONS

The majority of cases reported in the literature make reference to the difficulty of determining the pathogenic role of Streptomyces spp. Usually considered a contaminant, the pathogenic role of Streptomyces spp. is easier to confirm when the species is isolated from a catheter tip and, in the case of blood cultures, in more than one sample with a high count of colonies. To our knowledge, we report the first documented case of Streptomyces atratus bacteremic pneumonia in an immunocompetent patient. As the experience is limited, further studies are needed to better understand the interpretation of the isolates of the genus Streptomyces; the predisposing factors for infection; and the course, treatment, and evolution of these infections.

Orbital actinomycotic mycetoma caused byStreptomyces cinnamoneus

Case summary

An 18-month-old male neutered Ragdoll cat presented with an 8 week history of progressive unilateral right-sided mucopurulent nasal discharge and exophthalmos. Magnetic resonance imaging revealed a heterogeneous right retrobulbar mass and bilateral nasal cavity disease. Filamentous structures seen on cytology of retrobulbar and nasal biopsies were mistakenly identified as filamentous fungal hyphae. Subsequent investigations revealed that the cat had a retrobulbar actinomycotic mycetoma with invasion of the globe. The aetiological agent was identified on 16S recombinant DNA sequencing as Streptomyces cinnamoneus. After exenteration and chronic antimicrobial therapy the cat was alive and well 3 years after presentation.

Relevance and novel information

This is the first report of a pathogenic role of S cinnamoneus in a cat. Orbital actinomycotic mycetomas in cats can resemble mycotic granulomas.

Laser Capture Microdissection of Feline Streptomyces spp Pyogranulomatous Dermatitis and Cellulitis

Suspected Streptomyces spp infections were identified in 4 cats at UC Davis Veterinary Medical Teaching Hospital between 1982 and 2011. Three had ulcerated, dark red mycetomas involving the dermis, subcutis, and fascia with fistulous tracts and/or regional lymphadenopathy. One cat had pyogranulomatous mesenteric lymphadenitis. Granulomatous inflammation in all cats contained colonies of Gram-positive, non-acid-fast organisms. All 4 cats failed to respond to aggressive medical and surgical treatment and were euthanized. Laser capture microdissection (LCM) was used to selectively harvest DNA from the affected formalin-fixed, paraffin-embedded (FFPE) tissues. Cloned amplicons from LCM-derived tissue confirmed the presence of Streptomyces spp in the dermatitis cases. Amplicons from the remaining cat with peritoneal involvement aligned with the 16S ribosomal RNA gene for Actinomycetales. Usually considered a contaminant, Streptomyces spp can be associated with refractory pyogranulomatous dermatitis and cellulitis in cats with outdoor access. LCM is useful in the diagnosis of bacterial diseases where contamination may be an issue.

Case of keratitis caused by Streptomyces thermocarboxydus

We describe a case of keratitis caused by Streptomyces thermocarboxydus and report the usefulness of molecular analysis in identifying the exact species of Streptomyces. A 50-year-old man was diagnosed with keratitis caused by Streptomyces sp. which was identified as S. thermocarboxydus by sequencing the 16S rDNA. He had no history of trauma or systemic diseases. He was initially treated with topical beta-lactams and fluoroquinolones, and systemic beta-lactams but the keratitis did not improve. His vision improved significantly after topical erythromycin (5 mg/ml) and oral minocycline (200 mg/day) therapy. Our findings demonstrate that molecular analysis can be used to identify the exact Streptomyces species causing the keratitis. This then allowed us to determine the susceptibility of this species to different antibacterial drugs which were used to treat our patient successfully.

Antibiotic susceptibility patterns of Crossiella equi and Amycolatopsis species causing nocardioform placentitis in horses

Nocardioform actinomycetes are significant causes of placentitis and abortions in horses. In the current study, antimicrobial susceptibility patterns of 38 Amycolatopsis spp. and 22 Crossiella equi isolates, the most common nocardioform actinomycetes causing placentitis in horses, were evaluated. Antimicrobial susceptibilities of these isolates were tested by broth microdilution method in a commercial system, which was designed for Nocardia spp., fast-growing Mycobacterium spp., and other aerobic actinomycetes. The minimum inhibitory concentration required to inhibit the growth of 90% of organisms (MIC90) of the following antibiotics tested for Amycolatopsis spp. were: 4 µg/ml for linezolid, trimethophrim–sulfametaxazole (TMP-SMX), and ciprofloxacin; 8 µg/ml for ceftriaxone, doxycycline, and minocycline; 16 µg/ml for amoxicillin–clavulanic acid, clarithromycin, and imipenem; >16 µg/ml for tobramycin; 32 µg/ml for amikacin and cefepime; and 128 µg/ml for cefoxitin. The MIC90 levels for C. equi were 0.25 µg/ml for doxycycline; ≤1 µg/ml for minocycline; 2 µg/ml for linezolid and TMP-SMX; 4 µg/ml for ciprofloxacin; 8 µg/ml for amoxicillin–clavulanic acid, ceftriaxone, and imipenem; 16 µg/ml for clarithromycin; >16 µg/ml for tobramycin; 32 µg/ml for cefepime; >64 µg/ml for amikacin; and 128 µg/ml for cefoxitin.

Secondary peritonitis caused by Streptomyces viridis

Streptomyces organisms are soil inhabitants rarely causing nonmycetomic infections. We describe a case of secondary peritonitis caused by Streptomyces viridis in a chronic alcoholic patient who presented with fever, abdominal distension, and pain in the abdomen. The most likely source of infection was by inoculation through multiple paracenteses, done for treatment of ascites, before the patient came to our health care center. This is the second case report of Streptomyces peritonitis and the first case caused by Streptomyces viridis, which is usually found in the soil in our geographic region.

Scalp abscess due to Streptomyces cacaoi subsp. cacaoi, first report in a human infection

Streptomyces cacaoi subsp. cacaoi, a Gram-positive, branching filamentous bacteria, was isolated from a scalp infection in a patient from Pondicherry, India. Phenotypic tests identified the isolate as a Streptomyces species, but 16S rRNA sequence analysis provided the species identification required for tracking of this emerging pathogen.

Insights into cross-kingdom plant pathogenic bacteria

Plant and human pathogens have evolved disease factors to successfully exploit their respective hosts. Phytopathogens utilize specific determinants that help to breach reinforced cell walls and manipulate plant physiology to facilitate the disease process, while human pathogens use determinants for exploiting mammalian physiology and overcoming highly developed adaptive immune responses. Emerging research, however, has highlighted the ability of seemingly dedicated human pathogens to cause plant disease, and specialized plant pathogens to cause human disease. Such microbes represent interesting systems for studying the evolution of cross-kingdom pathogenicity, and the benefits and tradeoffs of exploiting multiple hosts with drastically different morphologies and physiologies. This review will explore cross-kingdom pathogenicity, where plants and humans are common hosts. We illustrate that while cross-kingdom pathogenicity appears to be maintained, the directionality of host association (plant to human, or human to plant) is difficult to determine. Cross-kingdom human pathogens, and their potential plant reservoirs, have important implications for the emergence of infectious diseases.

An unusual mechanism for brain abscess formation in a child

INTRODUCTION

Intracranial infection is an uncommon but serious complication of head injury.

CASE REPORT

This study describes a boy with a traumatic head injury caused by his mother's teeth stemming from a traffic accident, without initial alteration of consciousness or focal neurological signs, who subsequently developed an occipital lobe abscess 3 weeks later. Brain abscess culturing yielded human oral flora. To date, our case is the only report documenting skull fracture with subsequent brain abscess formation caused by human oral flora stemming from traumatic injury from his mother's teeth.

DISCUSSION

A high index of suspicion should be maintained, and early imaging such as computed tomography should be considered for patients with symptoms of intracranial infection or who are at high risk, even after a minor head injury. Early diagnosis, appropriate antibiotic therapy based on knowledge of the causative microbes, and surgery are the major prognostic factors for brain abscess.