Evaluation of Antibiotic Susceptibility of Gram-Positive Anaerobic Cocci Isolated from Cancer Patients of the N. N. Blokhin Russian Cancer Research Center

Hemoptysis caused by Parvimonas micra: case report and literature review

Background

Parvimonas micra (P. micra), a Gram-positive anaerobic bacterium, exhibits colonization tendencies on oral mucosal and skin surfaces, potentially evolving into a pathogenic entity associated with diverse diseases. The diagnostic trajectory for P. micra-related diseases encounters delays, often with severe consequences, including fatality, attributed to the absence of symptom specificity and challenges in culture. The absence of a consensus on the diagnostic and therapeutic approaches to P. micra exacerbates the complexity of addressing associated conditions. This study aims to elucidate and scrutinize the clinical manifestations linked to P. micra, drawing insights from an extensive literature review of pertinent case reports.

Case presentation

A 53-year-old male sought medical attention at our institution presenting with recurrent hemoptysis. Empirical treatment was initiated while awaiting pathogen culture results; however, the patient's symptoms persisted. Subsequent metagenomic next-generation sequencing (mNGS) analysis revealed a pulmonary infection attributable to P. micra. Resolution of symptoms occurred following treatment with piperacillin sulbactam sodium and moxifloxacin hydrochloride. A comprehensive literature review, utilizing the PubMed database, was conducted to assess case reports over the last decade where P. micra was identified as the causative agent.

Conclusion

The literature analysis underscores the predilection of P. micra for immunocompromised populations afflicted by cardiovascular diseases, diabetes, orthopedic conditions, and tumors. Risk factors, including oral and periodontal hygiene, smoking, and alcohol consumption, were found to be associated with P. micra infections. Clinical manifestations encompassed fever, cough, sputum production, and back pain, potentially leading to severe outcomes such as Spondylodiscitis, septic arthritis, lung abscess, bacteremia, sepsis, and mortality. While conventional bacterial culture remains the primary diagnostic tool, emerging technologies like mNGS offer alternative considerations. In terms of treatment modalities, β-lactam antibiotics and nitroimidazoles predominated, exhibiting recovery rates of 56.10% (46/82) and 23.17% (19/82), respectively. This case report and literature review collectively aim to enhance awareness among clinicians and laboratory medicine professionals regarding the intricacies of P. micra-associated infections.

Fifty years devoted to anaerobes: historical, lessons, and highlights

Renew interest and enthusiasm for anaerobes stem from both technological improvements (culture media, production of an adequate anaerobic atmosphere, identification methods) and greater awareness on the part of clinicians. Anaerobic infections were historically treated empirically, targeting the species known to be involved in each type of infection. Prevotella, fusobacteria, and Gram-positive cocci (GPAC) were considered responsible for infections above the diaphragm whereas for intra-abdominal infections, Bacteroides of the fragilis group (BFG), GPAC and clostridia were predominantly implicated. The antibiotic susceptibility of anaerobes was only taken into consideration by the clinician in the event of treatment failure or when faced with infections by multidrug-resistant bacteria (MDR). The evolution of antibiotic resistance together with clinical failures due to the absence of detection of hetero-resistant clones has resulted in a greater need for accessible antibiotic susceptibility testing (AST) and disc diffusion method. Improved isolation and identification of anaerobes, along with the availability of accessible and robust methods for performing AST, will ensure that treatment, whether empirical or guided by an antibiogram, will lead to better outcomes for anaerobic infections.

Understanding antimicrobial susceptibility profile of Finegoldia magna: an insight to an untrodden path

BACKGROUND

Finegoldia magna (formerly known as Peptococcus magnus or Peptostreptococcus magnus) belonging to phylum Firmicutes, class Clostridia and genus Finegoldia, is the only species known to cause infections in human beings. Amongst Gram positive anaerobic cocci, F. magna is known to be the most virulent with a high pathogenic potential. Significant upsurge in antimicrobial resistance among anaerobes has been documented by various studies. F. magna is known to be susceptible to most of the anti-anaerobic antimicrobials, however, multidrug resistant strains are being reported in literature. The present study was undertaken to highlight the role of F. magna in clinical infections and to analyze their antimicrobial susceptibility patterns.

METHODS

The present study was conducted in a tertiary care teaching hospital in Southern India. 42 clinical isolates of F. magna recovered from diverse clinical infections between January 2011 to December 2015 were studied. These isolates were subjected to antimicrobial susceptibility testing against metronidazole, clindamycin, cefoxitin, penicillin, chloramphenicol and linezolid.

RESULTS

Among the 42 isolates studied, majority of them were revived from diabetic foot infections (31%) followed by necrotizing fasciitis (19%) and deep-seated abscesses (19%). All the F. magna isolates showed good in-vitro activity against metronidazole, cefoxitin, linezolid and chloramphenicol. Clindamycin and penicillin resistance were observed against 9.5% and 2.4% of the isolates respectively. However, β-lactamase activity was not detected.

CONCLUSION

The antimicrobial resistance among anaerobes varies from pathogen to pathogen and region to region. Hence, a deep understanding of resistance pattern is necessary for better management of clinical infections.

Antimicrobial susceptibility of anaerobic clinical isolates: A two-year surveillance

A total of 866 anaerobic strains isolated from clinical samples were tested by E-TEST for antimicrobial susceptibility. The most frequent antimicrobial resistance among the isolated genera, both Gram-positive and Gram-negative, was observed for clindamycin, and therefore, it cannot be considered as an empirical treatment. The antimicrobial resistance to benzylpenicillin was predominant among the Gram-negative bacteria, in particular the Bacteroides spp. The resistance percentages to meropenem and metronidazole are still low. However, metronidazole showed a considerable resistance in Finegoldia magna isolates, alone or in combination with other antibiotics. These data provide novel and useful epidemiological information on infections promoted by anaerobic bacteria.

Antimicrobial susceptibility testing is crucial when treating Finegoldia magna infections

Finegoldia magna is an anaerobic gram-positive bacterium that can cause invasive human infections. Recently, a 52-year-old patient suffering from a periprosthetic joint infection (PJI) due to F. magna was treated with cefepime on hemodialysis; however, treatment failed due to relapse caused by antibiotic-resistant strains. Reports on the antimicrobial susceptibility of F. magna clinical isolates are rare. We collected 57 clinical F. magna isolates from Zurich, Switzerland, between September 2019 and July 2020 and tested their antimicrobial susceptibility to investigate the local resistance pattern. Antimicrobial susceptibility testing (AST) was evaluated for nine antibiotics (benzylpenicillin, amoxicillin/clavulanic acid, cefuroxime, cefepime, levofloxacin, rifampicin, metronidazole, doxycycline, and clindamycin) by E-test according to CLSI guidelines. All F. magna strains were susceptible to benzylpenicillin, amoxicillin/clavulanic acid, and metronidazole, while 75% to clindamycin. F. magna isolates showed MIC values lower than species-unrelated breakpoints for cefuroxime, levofloxacin, and cefepime in 93%, 56%, and 32% of the cases, respectively. MIC values for rifampicin and doxycycline were lower than locally determined ECOFFs in 98% and 72% of the cases, respectively. In summary, we recommend the use of benzylpenicillin, amoxicillin/clavulanic acid, or metronidazole without prior AST as first-line treatment option against F. magna PJI infections. If cefuroxime, cefepime, levofloxacin, rifampicin, doxycycline, or clindamycin are used, AST is mandatory.

Peptostreptococcus anaerobius: Pathogenicity, identification, and antimicrobial susceptibility. Review of monobacterial infections and addition of a case of urinary tract infection directly identified from a urine sample by MALDI-TOF MS

Peptostreptococcus anaerobius is a gram-positive anaerobic coccus (GPAC) found in the gastrointestinal and vaginal microbiota. The organism is mainly found in polymicrobial and scarcely in monobacterial infections such as prosthetic and native endocarditis. Anaerobic bacteria have rarely been reported as the cause of urinary tract infection (UTI). Although GPAC are susceptible to most antimicrobials used against anaerobic infections, P. anaerobius has shown to be more resistant. Herein, we report a case of UTI caused by P. anaerobius from a 62-year-old man with a history of urological disease. Surprisingly, the microorganism was directly identified by Matrix-Assisted Laser Desorption-Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) from the urine sample. The isolate was successfully identified by phenotypic methods, MALDI-TOF MS, and 16S rRNA gene sequencing. P. anaerobius showed no β-lactamase-producing activity, was resistant to penicillin, ampicillin, ciprofloxacin and levofloxacin, and displayed intermediate susceptibility to ampicillin-sulbactam and amoxicillin-clavulanic acid. Successful treatment was achieved with oral amoxicillin-clavulanic acid. Antimicrobial susceptibility testing (AST) should be performed on P. anaerobius isolates due to their unpredictable AST patterns and because empirically administered antimicrobial agents may not be active. This report shows that MALDI-TOF MS, directly used in urine specimens, may be a quick option to diagnose UTI caused by P. anaerobius or other anaerobic bacteria. This review is a compilation of monobacterial infections caused by P. anaerobius published in the literature, their pathogenicity, identification, and data about the antimicrobial susceptibility of P. anaerobius.

Native joint infections caused by Parvimonas micra

Parvimonas micra is an anaerobic, fastidious, gram positive organism commonly found in the oral cavity and gastrointestinal tract. It has been increasingly reported as the cause of septic arthritis of native joints, often times with delayed diagnosis leading to increased morbidity. Risk factors include immunosuppression, inflammation of the joint, and recent dental procedures or infections. It has been a historically difficult organism to culture. However, the development of and increasing use of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) has led to increased identification of P. micra. Common antibiotic susceptibilities, as well as data regarding susceptibilities in specific situations, have been reported, but susceptibility testing is required in all cases. Common treatments include clindamycin, penicillin, and metronidazole for six to ten weeks.

Clinical Characteristics of Chronic Lung Abscess Associated with Parvimonas micra Diagnosed Using Metagenomic Next-Generation Sequencing

Purpose

Parvimonas micra (P. micra) is a Gram-positive anaerobic bacterium distributed in the oral cavity, with a potential to become pathogenic causing lung abscess. Due to the lack of specificity of symptoms and the difficulty in culture, the diagnosis of lung abscess associated with P. micra is delayed. It is essential to elucidate the clinical characteristics of lung abscess associated with P. micra.

Methods

From January 2019 to July 2020, five patients with chronic lung abscess associated with P. micra diagnosed by pathological biopsy and metagenomic next-generation sequencing (mNGS) were analyzed in this retrospective study.

Results

Among the five patients, four had a history of smoking, three had periodontitis, and two had a history of drinking. The average course of the disease was 6.5 months. High-density flake-like or mass shadows with irregular boundaries were observed in the chest computed tomography (CT) images of the five patients, and liquefactive necrosis was detected in the middle of the lesions; however, no gas-liquid plane or cavity was noted, making it difficult to distinguish a lung cancer. The pathological biopsy of the five patients showed chronic inflammation of lung tissue, and P. micra was detected by mNGS in the biopsy or bronchoalveolar lavage fluid samples. Two patients were treated with amoxicillin-clavulanate, two had metronidazole, and one had moxifloxacin. Among them, four recovered after receiving antibiotic treatment, and the remaining one underwent surgical resection due to poor antibiotic treatment effect.

Conclusion

Chronic lung abscess associated with P. micra, common in elderly male smokers with poor oral hygiene, is often diagnosed in a delayed manner and misdiagnosed as lung cancer. The mNGS technology is beneficial to the rapid determination of P. micra.

Effect of oral consumption of capsules containing Lactobacillus paracasei LPC-S01 on the vaginal microbiota of healthy adult women: a randomized, placebo-controlled, double-blind crossover study

Oral consumption of probiotics is practical and can be an effective solution to preserve vaginal eubiosis. Here, we studied the ability of orally administered Lactobacillus paracasei LPC-S01 (DSM 26760) to affect the composition of the vaginal microbiota and colonize the vaginal mucosa in nondiseased adult women. A total of 40 volunteers took oral probiotic (24 billion CFU) or placebo capsules daily for 4 weeks, and after a 4-week washout, they switched to placebo or probiotic capsules according to the crossover design. A total of 23 volunteers completed the study according to the protocol. Before and after capsule ingestion, vaginal swabs were collected for qPCR quantification to detect L. paracasei LPC-S01 and for 16S rRNA gene sequencing. Vaginal swabs were grouped according to their bacterial taxonomic structure into nine community state types (CSTs), four of which were dominated by lactobacilli. Lactobacillus paracasei LPC-S01 was detected in the vagina of two participants. Statistical modeling (including linear mixed-effects model analysis) demonstrated that daily intake of probiotic capsules reduced the relative abundance of Gardnerella spp. Quantitative PCR with Gardnerella vaginalis primers confirmed this result. Considering the pathogenic nature of G. vaginalis, these results suggest a potential positive effect of this probiotic capsule on the vaginal microbial ecosystem.

16S rRNA Gene Amplicon Based Metagenomic Signatures of Rhizobiome Community in Rice Field During Various Growth Stages

Rice is a major staple food across the globe. Its growth and productivity is highly dependent on the rhizobiome where crosstalk takes place between plant and the microbial community. Such interactions lead to selective enrichment of plant beneficial microbes which ultimately defines the crop health and productivity. In this study, rhizobiome modulation is documented throughout the development of rice plant. Based on 16S rRNA gene affiliation at genus level, abundance, and diversity of plant growth promoting bacteria increased during the growth stages. The observed α diversity and rhizobiome complexity increased significantly (p < 0.05) during plantation. PCoA indicates that different geographical locations shared similar rhizobiome diversity but exerted differential enrichment (p < 0.001). Diversity of enriched genera represented a sigmoid curve and subsequently declined after harvest. A major proportion of dominant enriched genera (p < 0.05, abundance > 0.1%), based on 16S rRNA gene, were plant growth promoting bacteria that produces siderophore, indole-3-acetic acid, aminocyclopropane-1-carboxylic acid, and antimicrobials. Hydrogenotrophic methanogens dominated throughout cultivation. Type I methanotrophs (n = 12) had higher diversity than type II methanotrophs (n = 6). However, the later had significantly higher abundance (p = 0.003). Strong enrichment pattern was also observed in type I methanotrophs being enriched during water logged stages. Ammonia oxidizing Archaea were several folds more abundant than ammonia oxidizing bacteria. K-strategists Nitrosospira and Nitrospira dominated ammonia and nitrite oxidizing bacteria, respectively. The study clarifies the modulation of rhizobiome according to the rice developmental stages, thereby opening up the possibilities of bio-fertilizer treatment based on each cultivation stages.

Multidrug resistance in anaerobes

Multidrug resistance (MDR) in anaerobes is not a well-known topic. Bacteroides fragilis group isolates have numerous resistance determinants such as multidrug efflux pumps, cfiA and nimB genes and activating insertion sequences, and some isolates exhibited extensive drug-resistant patterns. MDR rates in B. fragilis group were from 1.5 to >18% and up to >71% in cfiA and nimB positive isolates carrying insertion sequences. MDR was present in >1/2 of Clostridioides difficile isolates, most often in epidemic/hypervirulent strains and unusually high metronidazole or vancomycin resistance has been reported in single studies. MDR was found in Prevotella spp. (in ≤10% of isolates), Finegoldia magna, Veillonella spp. and Cutibacterium acnes. Resistance in the anaerobes tends to be less predictable and anaerobic microbiology is required in more laboratories. New hopes may be new antibiotics such as eravacycline, cadazolid, surotomycin, ridinilazol or C. difficile toxoid vaccines; however, more efforts are needed to track the MDR in anaerobes.

Identification and Antimicrobial Susceptibility Testing of Anaerobic Bacteria: Rubik's Cube of Clinical Microbiology?

Anaerobic bacteria have pivotal roles in the microbiota of humans and they are significant infectious agents involved in many pathological processes, both in immunocompetent and immunocompromised individuals. Their isolation, cultivation and correct identification differs significantly from the workup of aerobic species, although the use of new technologies (e.g., matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, whole genome sequencing) changed anaerobic diagnostics dramatically. In the past, antimicrobial susceptibility of these microorganisms showed predictable patterns and empirical therapy could be safely administered but recently a steady and clear increase in the resistance for several important drugs (β-lactams, clindamycin) has been observed worldwide. For this reason, antimicrobial susceptibility testing of anaerobic isolates for surveillance purposes or otherwise is of paramount importance but the availability of these testing methods is usually limited. In this present review, our aim was to give an overview of the methods currently available for the identification (using phenotypic characteristics, biochemical testing, gas-liquid chromatography, MALDI-TOF MS and WGS) and antimicrobial susceptibility testing (agar dilution, broth microdilution, disk diffusion, gradient tests, automated systems, phenotypic and molecular resistance detection techniques) of anaerobes, when should these methods be used and what are the recent developments in resistance patterns of anaerobic bacteria.

Finegoldia magna Isolated from Orthopedic Joint Implant-Associated Infections

The anaerobic Gram-positive coccus Finegoldia magna is a rare cause of infections of bone and joints. The aim of this study was to describe the microbiological and clinical characteristics of orthopedic implant-associated infections caused by F. magna We retrospectively analyzed samples consisting of anaerobic Gram-positive cocci and samples already identified as F. magna from patients with orthopedic infections. The isolates found were determined to the species level using matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). The antibiotic susceptibility pattern was determined by Etest. Whole-genome sequencing (WGS) was performed. Clinical data were extracted from each patient's journal. In nine patients, orthopedic joint implant-associated infections were identified as being caused by F. magna The isolates were susceptible to most of the antibiotics tested, with the exception of rifampin and moxifloxacin in a few cases. Five of the nine infections were monomicrobial. The most common antibiotic used to treat the infection was penicillin V, but five of the nine patients received a combination of antibiotics. Eight patients underwent surgical treatment, with extraction of the implant performed in seven cases and reimplantation in only two cases. The WGS showed a relatively small core genome, with 126,647 single nucleotide polymorphisms identified within the core genome. A phylogenomic analysis revealed that the isolates clustered into two distinct clades. Orthopedic implant-associated infections caused by F. magna are rare, but the bacteria are generally susceptible to antibiotics. Despite this, surgical treatment combined with long-term antibiotics is often necessary. The WGS analysis revealed a high heterogeneity and suggested the existence of at least two different Finegoldia species.