Oral Gram-negative anaerobic bacilli as a reservoir of β-lactam resistance genes facilitating infections with multiresistant bacteria

Inter-phylum circulation of a beta-lactamase-encoding gene: a rare but observable event

Beta-lactamase-mediated degradation of beta-lactams is the most common mechanism of beta-lactam resistance in Gram-negative bacteria. Beta-lactamase-encoding genes can be transferred between closely related bacteria, but spontaneous inter-phylum transfers (between distantly related bacteria) have never been reported. Here, we describe an extended-spectrum beta-lactamase (ESBL)-encoding gene (blaMUN-1) shared between the Pseudomonadota and Bacteroidota phyla. An Escherichia coli strain was isolated from a patient in Münster (Germany). Its genome was sequenced. The ESBL-encoding gene (named blaMUN-1) was cloned, and the corresponding enzyme was characterized. The distribution of the gene among bacteria was investigated using the RefSeq Genomes database. The frequency and relative abundance of its closest homolog in the global microbial gene catalog (GMGC) were analyzed. The E. coli strain exhibited two distinct morphotypes. Each morphotype possessed two chromosomal copies of the blaMUN-1 gene, with one morphotype having two additional copies located on a phage-plasmid p0111. Each copy was located within a 7.6-kb genomic island associated with mobility. blaMUN-1 encoded for an extended-spectrum Ambler subclass A2 beta-lactamase with 43.0% amino acid identity to TLA-1. blaMUN-1 was found in species among the Bacteroidales order and in Sutterella wadsworthensis (Pseudomonadota). Its closest homolog in GMGC was detected frequently in human fecal samples. This is, to our knowledge, the first reported instance of inter-phylum transfer of an ESBL-encoding gene, between the Bacteroidota and Pseudomonadota phyla. Although the gene was frequently detected in the human gut, inter-phylum transfer was rare, indicating that inter-phylum barriers are effective in impeding the spread of ESBL-encoding genes, but not entirely impenetrable.

The oral microbiota is a reservoir for antimicrobial resistance: resistome and phenotypic resistance characteristics of oral biofilm in health, caries, and periodontitis

BACKGROUND

Antimicrobial resistance (AMR) is an ever-growing threat to modern medicine and, according to the latest reports, it causes nearly twice as many deaths globally as AIDS or malaria. Elucidating reservoirs and dissemination routes of antimicrobial resistance genes (ARGs) are essential in fighting AMR. Human commensals represent an important reservoir, which is underexplored for the oral microbiota. Here, we set out to investigate the resistome and phenotypic resistance of oral biofilm microbiota from 179 orally healthy (H), caries active (C), and periodontally diseased (P) individuals (TRN: DRKS00013119, Registration date: 22.10.2022). The samples were analysed using shotgun metagenomic sequencing combined, for the first time, with culture technique. A selection of 997 isolates was tested for resistance to relevant antibiotics.

RESULTS

The shotgun metagenomics sequencing resulted in 2,069,295,923 reads classified into 4856 species-level OTUs. PERMANOVA analysis of beta-diversity revealed significant differences between the groups regarding their microbiota composition and their ARG profile. The samples were clustered into three ecotypes based on their microbial composition. The bacterial composition of H and C samples greatly overlapped and was based on ecotypes 1 and 2 whereas ecotype 3 was only detected in periodontitis. We found 64 ARGs conveying resistance to 36 antibiotics, particularly to tetracycline, macrolide-lincosamide-streptogramin, and beta-lactam antibiotics, and a correspondingly high prevalence of phenotypic resistance. Based on the microbiota composition, these ARGs cluster in different resistotypes, and a higher prevalence is found in healthy and caries active than in periodontally diseased individuals. There was a significant association between the resistotypes and the ecotypes. Although numerous associations were found between specific antibiotic resistance and bacterial taxa, only a few taxa showed matching associations with both genotypic and phenotypic analyses.

CONCLUSIONS

Our findings show the importance of the oral microbiota from different niches within the oral cavity as a reservoir for antibiotic resistance. Additionally, the present study showed the need for using more than one method to reveal antibiotic resistance within the total oral biofilm, as a clear mismatch between the shotgun metagenomics method and the phenotypic resistance characterization was shown.

Systematic literature review of the disease burden and vaccination of pneumococcal disease among adults in select Asia-Pacific areas

INTRODUCTION

Pneumococcal diseases are common and cause significant morbidity and mortality, with higher rates especially in developing areas including many in the Asia-Pacific (AP) region. However, current strategies to prevent pneumococcal disease in adults are quite complicated and not well implemented among many AP areas, and vaccination coverage rates among adults are generally low or perceived as low in the region. Thus, this literature review's purpose was to summarize the disease burden and vaccination against pneumococcal diseases among adults in select AP areas (Australia, Hong Kong, India, Indonesia, South Korea, Malaysia, New Zealand, the Philippines, Singapore, Taiwan, Thailand, and Vietnam).

AREAS COVERED

This systematic review included published articles from January 2010 to August 2020 using MEDLINE/Embase. Grey literature websites were searched for national immunization programs and medical society vaccination recommendations from areas of interest. A total of 69 publications were identified.

EXPERT OPINION

In the AP region, pneumococcal disease burden and serotype prevalence are variable among adult populations, particularly among older adults. Data was provided primarily from countries with established national immunization programs (NIPs). Further research on the disease burden and emphasis on the benefits of vaccination in AP areas lacking pneumococcal vaccination programs is warranted.

Etiology and antimicrobial susceptibility profiles of anaerobic bacteria isolated from clinical samples in a university hospital in Madrid, Spain

BACKGROUND

The anaerobic infection management is usually based on empirical treatment because anaerobic culture techniques take a long time due to their fastidious nature. The aim of this study was to analyze the etiological profile of severe anaerobic infections and AST data from clinical anaerobic bacteria isolated in a tertiary hospital in Madrid (Spain).

MATERIAL AND METHODS

A consecutive study was carried out over 19 months in Ramón y Cajal Universitary Hospital, Madrid. Clinical samples were processed in appropriate anaerobic media and incubated using Anoxomat system. Identification was performed by MALDI-TOF. AST were determined with gradient diffusion method using EUCAST (penicillin, co-amoxiclav, imipenem, clindamycine and metronidazole) or CLSI (cefoxitin) breakpoints.

RESULTS

During the period of study, 503 anaerobic microorganisms isolated from 424 clinical samples were included. Twenty-six percent of the cultures were monomicrobial, while 70.0% also contained aerobic bacteria. The most common source of infection was abscesses (26%), while blood infections represented the 11%. Anaerobic gram-negative bacilli were predominant (41%), being Bacteroides fragilis (13%) the most prevalent overall; anaerobic gram-positive bacilli represented 35%, anaerobic gram-positive cocci 19% and anaerobic gram-negative cocci 5%. Metronidazole and imipenem were the most effective agents tested against anaerobic bacteria, while clindamycin presented higher resistance rates.

CONCLUSION

Antimicrobial susceptibility surveillance of anaerobic bacteria should be performed to monitor changes in resistance patterns and to be able to optimize empiric antimicrobial treatment. Reliable species identification and quick reporting of results would guide clinicians to select the optimal antimicrobial therapy.

Oral Health Disorders in Parkinson's Disease: More than Meets the Eye

Despite clinical evidence of poor oral health and hygiene in Parkinson’s disease (PD) patients, the mouth is often overlooked by both patients and the medical community, who generally focus on motor or psychiatric disorders considered more burdensome. Yet, oral health is in a two-way relationship with overall health—a weakened status triggering a decline in the quality of life. Here, we aim at giving a comprehensive overview of oral health disorders in PD, while identifying their etiologies and consequences. The physical (abnormal posture, muscle tone, tremor, and dyskinesia), behavioral (cognitive and neuropsychiatric disorders), and iatrogenic patterns associated with PD have an overall detrimental effect on patients’ oral health, putting them at risk for other disorders (infections, aspiration, pain, malnutrition), reducing their quality of life and increasing their isolation (anxiety, depression, communication issues). Interdisciplinary cooperation for prevention, management and follow-up strategies need to be implemented at an early stage to maintain and improve patients’ overall comfort and condition. Recommendations for practice, including (non-)pharmacological management strategies are discussed, with an emphasis on the neurologists’ role. Of interest, the oral cavity may become a valuable tool for diagnosis and prognosis in the near future (biomarkers). This overlooked but critical issue requires further attention and interdisciplinary research.

Prevotella melaninogenica, a Sentinel Species of Antibiotic Resistance in Cystic Fibrosis Respiratory Niche?

The importance and abundance of strict anaerobic bacteria in the respiratory microbiota of people with cystic fibrosis (PWCF) is now established through studies based on high-throughput sequencing or extended-culture methods. In CF respiratory niche, one of the most prevalent anaerobic genera is Prevotella, and particularly the species Prevotella melaninogenica. The objective of this study was to evaluate the antibiotic susceptibility of this anaerobic species. Fifty isolates of P. melaninogenica cultured from sputum of 50 PWCF have been included. Antibiotic susceptibility testing was performed using the agar diffusion method. All isolates were susceptible to the following antibiotics: amoxicillin/clavulanic acid, piperacillin/tazobactam, imipenem and metronidazole. A total of 96% of the isolates (48/50) were resistant to amoxicillin (indicating beta-lactamase production), 34% to clindamycin (17/50) and 24% to moxifloxacin (12/50). Moreover, 10% (5/50) were multidrug-resistant. A significant and positive correlation was found between clindamycin resistance and chronic azithromycin administration. This preliminary study on a predominant species of the lung “anaerobiome” shows high percentages of resistance, potentially exacerbated by the initiation of long-term antibiotic therapy in PWCF. The anaerobic resistome characterization, focusing on species rather than genera, is needed in the future to better prevent the emergence of resistance within lung microbiota.

Carriage of antibiotic resistant bacteria flora and its role in the guidance of clinical decision making

There is considerable literature on the threat of antibiotic resistance and its impact on morbidity. However, an under-studied consideration is how carriage of these antibiotic resistant bacteria persist in an individual. The duration that a person harbors a resistant organism is critical in guiding future antimicrobial therapy. Key unexplored questions are the rate of clearance of these organisms and what drives their persistence. This paper attempts to examine these questions and offers some initial answers as well as avenues for further study.

Prevalence and antimicrobial susceptibility of Gram-negative bacilli in subgingival biofilm associated with periodontal diseases

BACKGROUND

This cross-sectional study aimed to determine the prevalence and antimicrobial susceptibility of Gram-negative bacilli (GNB) isolated from subgingival biofilm of individuals with different periodontal conditions.

METHODS

Subgingival biofilm was obtained from 362 individuals with periodontal health (PH) (n = 83), gingivitis (n = 74), and periodontitis (n = 205), cultivated in broth and selective media. Isolated strains were identified by mass spectrometry. Antimicrobial susceptibility was determined by the Clinical and Laboratory Standards Institute disk diffusion guidelines. Production of extended-spectrum beta-lactamase (ESBL) and carbapenemases were evaluated by double disk synergy test and spectrophotometric detection of imipenem hydrolysis, respectively. ESBL and carbapenemase encoding genes were surveyed by Polymerase chain reaction (PCR). Differences among groups were examined by Chi-square, Kruskal-Wallis or Mann-Whitney tests.

RESULTS

GNB were isolated from 36.2% of all subgingival biofilm samples, with a significantly greater prevalence and species diversity (P < 0.001) in patients with periodontitis (45.9%) compared with individuals with PH (24.1%) and gingivitis (22.9%). Pseudomonas aeruginosa (27.5%), Enterobacter cloacae (16.8%), and Enterobacter asburiae (10.7%) were the most predominant species. Resistance/reduced sensitivity to at least 1 antimicrobial was detected in 60% of the strains, but only 4.6% were multidrug resistant. Serratia marcescens, E. cloacae, and Enterobacter kobei presented high rates of intrinsic resistance (>40%) to amoxicillin-clavulanate and first/second-generations of cephalosporins. One strain of Klebsiella pneumoniae isolated from periodontitis was resistant to imipenem, but no ESBL encoding genes or ESBL phenotype was detected.

CONCLUSION

High prevalence and diversity of GNB, with low susceptibility to β-lactams are observed in the subgingival microbiota associated with periodontitis.

Medical and surgical characteristics of fusobacterium necrophorum mastoiditis in children

OBJECTIVES

To evaluate and compare characteristics of Fusobacterium necrophorum mastoiditis (FnM) to characteristics of acute mastoiditis (AM) caused by other bacteria in tertiary children hospital Methods : Children with FnM (N=43) and non FnM (N=88). Assess medical, microbiologic and imaging characteristics, surgical findings and postoperative recovery.

RESULTS

Children with FnM had a positive history of otitis media, ear discharge and sub-periosteal abscess (p=0.0004, 0.09, 0.0003, respectively) at presentation. Their temperature, WBC and CRP were significantly higher (39.8 vs. 37.9, 19.4K vs. 16.1K, 21 vs. 8.7, p=0.0001). Positive culture was found in 46% of patients; 64% were diagnosed by PCR. CT scan was indicated in 95% and surgical intervention in 93% of children with FnM, compared to 15% and 9.7% of children in the non-FnM group (p=0.0001). Complex post-operative course was frequent for the FnM group: 88% of children had persistent fever, 46% had additional imaging and 14% additional surgical intervention. Children with FnM were treated with IV antibiotics for an average of 22 compared to seven days for non-FnM children (p=0.0001).

CONCLUSIONS

Fusobacterium should be suspect in a child presenting with AM, a septic appearance, high fever and increased inflammation markers. A regimen of two antibiotics should be empirically started, then proceed to imaging and early surgical intervention. A relatively slow post-operative recovery process should be expected; however, prognosis is good.

Bacterial diversity and prevalence of antibiotic resistance genes in the oral microbiome

OBJECTIVES

This study aims to describe the oral microbiome diversity and prevalence of ARGs in periodontal health and disease.

BACKGROUND

The human oral cavity harbors a complex microbial community known as the oral microbiome. These organisms are regularly exposed to selective pressures, such as the usage of antibiotics, which drive evolution and acquisition of antibiotic resistance genes (ARGs). Resistance among oral bacteria jeopardizes not only antibiotic therapy for oral infections, but also extra-oral infections caused by bacterial translocation.

METHODS

We carried out a cross-sectional investigation. Saliva and subgingival plaque samples were collected during a clinical exam. 16S rRNA gene sequencing was performed to assess microbial diversity. Resistance genes were identified through PCR assays.

RESULTS

Of the 110 participants, only 22.7% had healthy periodontium, while the majority was diagnosed with gingivitis (55.4%) and chronic periodontitis (21.8%). The composition of the oral microbiota differed from healthy and diseased samples, being Streptococcus spp. and Rothia spp. predominant in periodontal disease. Regarding ARGs, 80 (72.7%) samples were positive for at least one of genes screened, erm being the most frequent variant (58.2%), followed by blaTEM (16.4%), mecA (2.7%), pbp2b and aac(6 ') (1.8%). Neither genes coding resistance to carbapenems nor metronidazole were detected.

CONCLUSIONS

Our findings indicate that there are no significant differences in terms of taxonomic enrichment between healthy and diseased oral microbiomes. However, samples retrieved from healthy patients had a more diverse microbial community, whereas diseased samples have lower taxonomic diversity. We have also identified clinically relevant ARGs, providing baseline information to guide antibiotic prescription in dentistry.

Screening for prevalence and abundance of Capnocytophaga spp by analyzing NGS data: A scoping review

BACKGROUND

Capnocytophaga spp. are commensal bacteria of the oral cavity and constitute a genus of the core microbiome.

OBJECTIVE

This genus is responsible for many local and systemic conditions in both the immunocompetent and immunocompromised patients, but its beneficial or deleterious role in the microbiota has been little explored.

DESIGN

Online databases were used to identify papers published from 1999 to 2019 based on next-generation sequencing (NGS) data to study comparative trials. Work using other identification methods, case reports, reviews, and non-comparative clinical trials was excluded.

RESULTS AND CONCLUSION

We selected 42 papers from among 668 publications. They showed a link between the abundance of Capnocytophaga spp. in the oral microbiota and various local pathologies (higher for gingivitis and halitosis; lower in active smokers, etc.) or systemic diseases (higher for cancer and carcinomas, IgA nephropathy, etc.). After discussing the limits inherent to the NGS techniques, we present several technical and biological hypotheses to explain the diversity of results observed between studies, as well as the links between the higher or lower abundance of Capnocytophaga spp and the appearance of local or systemic conditions and diseases.

Resistencia a antibióticos β-lactámicos y eritromicina en bacterias de la cavidad oral

Introducción. La microbiota humana como fuente de bacterias y genes de resistencia constituyen un problema de salud pública. En este estudio se investigó la prevalencia de bacilos entéricos Gram negativos resistentes a β-lactámicos y de los Streptococcus del grupo viridans (EGV) con resistencia a eritromicina en la cavidad oral. Métodos. Se realizó un estudio descriptivo de corte transversal con 193 aislamientos de la cavidad oral sana de 178 adultos que asistieron a una Clínica Odontológica de la ciudad de Cali durante el 2018. La evaluación de la sensibilidad antimicrobiana se realizó en 59 bacilos entéricos y 134 EGV y se identificó por PCR los genes que confieren resistencia a β-lactámicos y eritromicina. El análisis estadístico se realizó mediante el empleo del paquete SPSS vs 23. Resultados. El 84,7% de los bacilos entéricos fueron multirresistentes y presentaron genes bla, siendo blaTEM-1 (49,2%) y blaVIM-2 (30,5%,) los más prevalentes. Los EGV fueron resistentes a eritromicina (38,8%) y clindamicina (28,4%). El 18,7% presentaron el fenotipo cMLSβ, 4,5% el iMLSβ y el 14,9% fueron M.  El gen ermB se detectó en los cMLSβ, (13,4%) y el gen mef  en los M (9,7%). Conclusión. En este estudio se demostró la presencia de EGV y bacilos entéricos resistentes a los antibióticos y portadores de genes de resistencia a eritromicina y genes bla en la cavidad oral sana. La presencia de estas bacterias representa un riesgo para la salud de los individuos portadores y contribuyen a la creciente epidemia de resistencia bacteriana.

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.

Structure-based classification of class A beta-lactamases, an update

Beta-lactamase (EC 3.5.2.6) synthesis, particularly in Gram-negative bacilli, is a major mechanism of natural and acquired resistance to beta-lactams, sometimes accompanied by impermeability and/or active efflux. These enzymes have been classified into four molecular classes (A-D). The serine enzymes of class A, which may be encoded by the bacterial chromosome or transferable elements and are susceptible to clinically available inhibitors (clavulanic acid, sulbactam, tazobactam, avibactam), are prevalent considering other molecular classes (B,C,D). The continual rapid development of genomic approaches and tremendous progress in automatic sequencer technology have resulted in the accumulation of massive amounts of data. A structure-based classification of class A beta-lactamases based on specific conserved motifs involved in catalytic mechanisms and/or substrate binding (S⁷⁰XXK, S¹³⁰DN, K²³⁴TG), together with E166 (Ambler numbering) and at least 24 other amino-acid residues or analogs such as G45, F66, V80, L81, L91, L101, P107, A134, L138, G143, G144, G156, L169, T181, T182, P183, was validated on 700 amino-acid sequences, including 132 representative types, but mostly probable enzyme sequences, many produced by environmental bacteria. Two subclasses (A1, A2), six major clusters or groups (e.g. natural limited-spectrum beta-lactamases (LSBL), wider spectrum beta-lactamases (WSBL), and various other clusters were identified on the basis of conserved (> 90%) and specific motifs, and residues such as S⁷⁰TFKAL, S¹³⁰DNTAANL, R¹⁶⁴XEXXLN, V²³¹GDKTG for subclass A1, S⁷⁰VFKFH, S¹³⁰DNNACDI,E¹⁶⁶XXM, and V²³¹AHKTG for subclass A2, a probable disulfide bridge C77-C123 and G236, A237, G238, and R244 for the LSBL group. This great diversity of primary structures was used as the basis for a structure-based and phylogenetic classification.

Anaerobes in cystic fibrosis patients' airways

Anaerobes are known to constitute an important part of the airway microbiota in both healthy subjects and cystic fibrosis (CF) patients. Studies on the potential role of anaerobic bacteria in CF and thus their involvement in CF pathophysiology have reported contradictory results, and the question is still not elucidated. The aim of this study was to summarize anaerobe diversity in the airway microbiota and its potential role in CF, to provide an overview of the state of knowledge on anaerobe antibiotic resistances (resistome), and to investigate the detectable metabolites produced by anaerobes in CF airways (metabolome). This review emphasizes key metabolites produced by strict anaerobic bacteria (sphingolipids, fermentation-induced metabolites and metabolites involved in quorum-sensing), which may be essential for the better understanding of lung disease pathophysiology in CF.

Involvement of PorK, a component of the type IX secretion system, in Prevotella melaninogenica pathogenicity

Prevotella melaninogenica is a gram-negative anaerobic commensal bacterium that resides in the human oral cavity and is isolated as a pathogen of suppurative diseases both inside and outside the mouth. However, little is known about the pathogenic factors of P. melaninogenica. The periodontal pathogens Porphyromonas gingivalis and Tanerella forsythia secrete virulence factors such as protease and bacterial cell surface proteins via a type IX secretion system (T9SS) that are involved in pathogenicity. P. melaninogenica also possesses all known orthologs of T9SS. In this study, a P. melaninogenica GAI 07411 mutant deficient in the orthologue of the T9SS-encoding gene, porK, was constructed. Hemagglutination and biofilm formation were decreased in the porK mutant. Furthermore, following growth on skim milk-containing medium, the diameters of the halos surrounding the porK mutant were smaller than those of the wild-type strain, suggesting a decrease in secretion of proteases outside the bacterium. To investigate this in detail, culture supernatants of wild-type and porK mutant strains were purified and compared by two-dimensional electrophoresis. In the mutant strain, fewer spots were detected, indicating fewer secreted proteins. In infection experiments, the mortality rate of mice inoculated with the porK mutant strain was significantly lower than in the wild-type strain. These results suggest that P. melaninogenica secretes potent virulence factors via the T9SS that contribute to its pathogenic ability.

Transposons: the agents of antibiotic resistance in bacteria

Transposons are a group of mobile genetic elements that are defined as a DNA sequence. Transposons can jump into different places of the genome; for this reason, they are called jumping genes. However, some transposons are always kept at the insertion site in the genome. Most transposons are inactivated and as a result, cannot move. Transposons are divided into two main groups: retrotransposons (class І) and DNA transposons (class ІІ). Retrotransposons are often found in eukaryotes. DNA transposons can be found in both eukaryotes and prokaryotes. The bacterial transposons belong to the DNA transposons and the Tn family, which are usually the carrier of additional genes for antibiotic resistance. Transposons can transfer from a plasmid to other plasmids or from a DNA chromosome to plasmid and vice versa that cause the transmission of antibiotic resistance genes in bacteria. The treatment of bacterial infectious diseases is difficult because of existing antibiotic resistance that part of this antibiotic resistance is caused by transposons. Bacterial infectious diseases are responsible for the increasing rise in world mortality rate. In this review, transposons and their roles have been studied in bacterial antibiotic resistance, in detail.

Capnocytophaga spp. infection causing chorioamnionitis: an unusual suspect

Capnocytophaga spp. are not often considered as a cause of perinatal infection. However, Capnocytophaga spp. are a commensal of the human oral cavity and can be opportunistic pathogens. The present case illustrates the ability of a species from the human oral cavity, C. sputigena, to cause an ascending infection of the genital tract in a healthy pregnant woman.

Genomic analysis reveals the presence of a class D beta-lactamase with broad substrate specificity in animal bite associated Capnocytophaga species

Capnocytophga canimorsus and Capnocytophga cynodegmi can be transmitted from cats and dogs to humans, and can cause a wide range of infections including wound infections, sepsis, or endocarditis. We and others recently discovered two new Capnocytophaga species, C. canis and C. stomatis, mainly associated with wound infections. The first-line treatment of animal bite related infections is penicillin, and in case of allergy, doxycycline and trimethoprim/sulfamethoxazole. However, there is a lack of antibiotic susceptibility patterns for animal bite associated Capnocytophaga species. Thus, we set out to study the antibiotic profiles against animal bite associated Capnocytophaga species isolated from wound and blood cultures after cat and dog bites and coupled the findings to whole genome sequencing data. A total of 24 strains were included in the study. Phenotypic analysis of antibiotic resistance was performed with E-tests. The web-based tool 'Resfinder' was used to identify resistance genes in the whole genome dataset. Two strains of C. cynodegmi and two strains of the recently discovered C. stomatis were resistant to penicillin (MIC > 24 mg/L) and cephalosporins (MIC > 24 mg/L), and three out of these strains also exhibited resistance to imipenem (MIC = 32 mg/L). Genomic analysis revealed that these strains carried a class D beta-lactamase gene, which has not previously been found in Capnocytophaga spp. A class D beta lactamase with broad substrate specificity was found in animal bite associated Capnocytophaga species, which could have important implications when treating wound infections after cat and dog bites. It also suggests that pet animal bacteria can harbour resistance genes with relevance for human infections.

The gut resistome is highly dynamic during the first months of life

AIM

We investigated the longitudinal development of several antibiotic resistance genes (ARGs) of the infant gut resistome during the first months after birth.

MATERIALS & METHODS

Fecal samples from 120 infants collected at the ages of 5, 13 and 31 weeks were analyzed and subjected to qPCR for the detection of several ARGs.

RESULTS

The prevalence of ARGs significantly increased for ermB, tetM and tetQ, while it decreased for aac(6')-aph(2'). Birth mode and breastfeeding significantly affected tetQ prevalence. Correlations to bacterial taxa suggest that fluctuations in some ARGs are (partly) attributed to shifts in bacteroides colonization rates.

CONCLUSION

Acquisition of ARGs in the gut microbiota occurs shortly after birth and resistome composition fluctuates over the course of several months, reflecting changes in microbial community structure.

Fusobacterium necrophorum otitis and mastoiditis in infants and young toddlers

There is an increased recovery of Fusobacterium necrophorum from cases of otitis media and mastoiditis in the pediatric population. These infections may be highly severe, causing local osteomyelitis, bacteremia, and Lemierre's syndrome. The severity and difficulties in providing optimal treatment for these infections may be especially difficult in this age group due to immunological immaturity and delayed presentation. In this review of literature, we present and analyze the clinical presentation, management, and outcome of otic infections caused by F. necrophorum in infants and young toddlers less than 2 years old. Search in Pubmed was conducted for reported cases in the English literature for the time period of the last 50 years. Twelve well-described cases were retrieved with F. necrophorum otitis and mastoiditis and complications reported in all cases. Treatment included both intravenously with antimicrobial agents (beta lactams plus metronidazole) and mastoidectomy. Lemierre's syndrome and Lemierre's syndrome variants developed in 60 % of the patients. Dissemination of the infection as distal osteomyelitis and septic shock were also reported. The outcome was favorable in all the cases. Otitis and mastoiditis infections in children less then 2 years old are invasive infections, and severe complications can occur.

Should Antibiotics Be Prescribed to Treat Chronic Periodontitis?

Although scaling and root planing is a cost-effective approach for initial treatment of chronic periodontitis, it fails to eliminate subgingival pathogens and halt progressive attachment loss in some patients. Adjunctive use of systemic antibiotics immediately after completion of scaling and root planing can enhance the degree of clinical attachment gain and probing depth reduction provided by nonsurgical periodontal treatment. This article discusses the rationale for prescribing adjunctive antibiotics, reviews the evidence for their effectiveness, and outlines practical issues that should be considered before prescribing antibiotics to treat chronic periodontitis.