Antimicrobial susceptibility of clinical isolates of anaerobic bacteria in Ontario, 2010-2011

Recent development and fighting strategies for lincosamide antibiotic resistance

SUMMARYLincosamides constitute an important class of antibiotics used against a wide range of pathogens, including methicillin-resistant Staphylococcus aureus. However, due to the misuse of lincosamide and co-selection pressure, the resistance to lincosamide has become a serious concern. It is urgently needed to carefully understand the phenomenon and mechanism of lincosamide resistance to effectively prevent and control lincosamide resistance. To date, six mobile lincosamide resistance classes, including lnu, cfr, erm, vga, lsa, and sal, have been identified. These lincosamide resistance genes are frequently found on mobile genetic elements (MGEs), such as plasmids, transposons, integrative and conjugative elements, genomic islands, and prophages. Additionally, MGEs harbor the genes that confer resistance not only to antimicrobial agents of other classes but also to metals and biocides. The ultimate purpose of discovering and summarizing bacterial resistance is to prevent, control, and combat resistance effectively. This review highlights four promising strategies, including chemical modification of antibiotics, the development of antimicrobial peptides, the initiation of bacterial self-destruct program, and antimicrobial stewardship, to fight against resistance and safeguard global health.

Actinomyces spp. Prosthetic Vascular Graft Infection (PVGI): A Multicenter Case-Series and Narrative Review of the Literature

BACKGROUND

Actinomycosis represents a challenging and under-reported complication of vascular surgery. Optimal management of Actinomyces spp. prosthetic vascular graft infection (PVGI) is highly uncertain because of the paucity of reports on this disease.

METHODS

We conducted a retrospective case-series of Actinomyces-PVGI that occurred in the last five years in two major university hospitals in northern Italy. We searched for previously published cases in the scientific literature.

RESULTS

We report five original cases of Actinomyces spp. prosthetic vascular graft infection following aortic aneurysm repair. Our literature review retrieved eight similar cases. Most patients were immunocompetent males. Most infections were polymicrobial (11/13 cases), with a prevalence of A. odontolyticus involvement (3/13 cases were associated with. Salmonella spp. infection). All cases had a late presentation (≥4 months from graft placement), with 61% associated with an aorto-enteric fistula. All patients received antibiotic therapy, but the duration was highly heterogeneous (from two weeks to life-long antibiotics). The patients without surgical revision experienced septic recurrences (2/13), permanent dysfunction (1/13), or a fatal outcome (2/13), while of the remainder who underwent vascular graft explant, six recovered completely and one developed a periprosthetic abscess. In two cases follow-up was not available.

CONCLUSIONS

This case-series aims to raise the diagnostic suspicion and to describe the current management of Actinomyces-PVGIs. We highlight a high heterogeneity in antibiotic duration, choice of the antibiotic regimen, and surgical management. Higher reporting rate is advisable to produce better evidence and optimize management of this rare complication of vascular surgery.

Antimicrobial resistance pattern of anaerobic bacteria causing lower respiratory tract infections

BACKGROUND

Anaerobes are normal flora of the human body. However, they can cause serious infections in humans. Anaerobic bacteria are known to cause respiratory infections like pneumonia and acute exacerbation of chronic lower airway infections. These are often missed due to the complexity of their isolation and identification. Hence, this study aimed to study anaerobes causing respiratory tract infections and determine their antibiotic susceptibility.

MATERIALS & METHODS

Clinical specimens such as bronchial aspirates and pleural aspirates collected from patients with respiratory diseases attending Vallabhbhai Patel Chest Institute were processed, the anaerobes isolated were identified, and their susceptibilities to various groups of antimicrobials were studied using standard microbiological methods.

RESULTS

Three hundred and fourteen patients were included in the study, 154 males and 160 females. Of these 314 patients, 148 (47%) yielded anaerobes in their clinical samples. Seventy patients had more than one type of anaerobic organism. Hence, 235 isolates were recovered belonging to as many as 17 genera. The MIC of seven antibiotics on 154 isolates was tested. The isolates belonged mostly to the genera Bacteroides, Prevotella, Veillonella, and Actinomyces. Variable resistance was observed to most classes of antibiotics by many genera.

CONCLUSIONS

Metronidazole is commonly used against anaerobes, but the study showed that the isolates were 20-30% resistant to the antibiotic. Starting this as an empirical therapy might lead to treatment failure.

Genome characteristics of the optrA-positive Clostridium perfringens strain QHY-2 carrying a novel plasmid type

Clostridium perfringens is a bacterial species of importance to both public and animal health. The gene optrA is the first gene that confers resistance to the tedizolid, a last-resort antimicrobial agent in human medicine. Herein, we whole-genome sequenced and analyzed one optrA-positive C. perfringens strain QHY-2 from Tibetan sheep in Qinghai province and identified one optrA plasmid pQHY-2. The plasmid shared similar structure with the optrA-positive plasmids p2C45 and p21-D-5b previously identified in C. perfringens, demonstrating the potential horizontal transmission of the optrA plasmids among C. perfringens strains. Annotation of the optrA-positive plasmids showed optrA and erm(A) located on a segment flanked by IS element IS1216E, and fexA, optrA, and erm(A) located on a segment flanked by IS element ISVlu1, which revealed the possible dissemination mechanism. Additionally, a Tn6218-like transposon carrying aac(6')-aph(2″) and erm(B) was also detected on pQHY-2, demonstrating the transposition of Tn6218 and spread of antibiotic resistance among Clostridium bacteria. Molecular analysis indicated the optrA-positive plasmids belonged to a plasmid type distinct from the pCW3-like plasmids, pCP13-like plasmids, or pIP404-like plasmids. Further structure analysis showed they might be formed by inserting segments into plasmid pCPCPI53k-r1_1, which coexist with two pCW3-like plasmids and one pCP13-like plasmid in C. perfringens strain CPI 53k-r1 isolated from a healthy human in Finland. IMPORTANCE Antimicrobial resistance is now a global concern posing threats to food safety and public health. The pCW3-like plasmids can encode several main toxin genes and three antibiotic resistance genes (ARGs), including tetA(P), tetB(P), and erm(B), which used to be considered as the main carrier of ARGs in Clostridium perfringens. In this study, we found the optrA plasmids, which belonged to a novel plasmid type, could also harbor many other ARGs, indicating this type of plasmid might be the potential repository of ARGs in C. perfringens. Additionally, this type of plasmid could coexist with the pCW3-like plasmids and pCP13-like plasmids that encoded toxin genes associated with gastrointestinal diseases, which showed the potential threat to public health.

The epidemiology, clinical presentation and treatment outcomes in CNS actinomycosis: a systematic review of reported cases

BACKGROUND

CNS actinomycosis is a rare chronic suppurative infection with non-specific clinical features. Diagnosis is difficult due to its similarity to malignancy, nocardiosis and other granulomatous diseases. This systematic review aimed to evaluate the epidemiology, clinical characteristics, diagnostic modalities and treatment outcomes in CNS actinomycosis.

METHODS

The major electronic databases (PubMed, Google Scholar, and Scopus) were searched for the literature review by using distinct keywords: "CNS" or "intracranial" or "brain abscess" or "meningitis" OR "spinal" OR "epidural abscess" and "actinomycosis." All cases with CNS actinomycosis reported between January 1988 to March 2022 were included.

RESULTS

A total of 118 cases of CNS disease were included in the final analysis. The mean age of patients was 44 years, and a significant proportion was male (57%). Actinomycosis israelii was the most prevalent species (41.5%), followed by Actinomyces meyeri (22.6%). Disseminated disease was found in 19.5% of cases. Most commonly involved extra-CNS organs are lung (10.2%) and abdomen (5.1%). Brain abscess (55%) followed by leptomeningeal enhancement (22%) were the most common neuroimaging findings. Culture positivity was found in nearly half of the cases (53.4%). The overall case-fatality rate was 11%. Neurological sequelae were present in 22% of the patients. On multivariate analysis, patients who underwent surgery with antimicrobials had better survival (adjusted OR 0.14, 95% CI 0.04-0.28, p value 0.039) compared to those treated with antimicrobials alone.

CONCLUSION

CNS actinomycosis carries significant morbidity and mortality despite its indolent nature. Early aggressive surgery, along with prolonged antimicrobial treatment is vital to improve outcomes.

Recent Trends in Antimicrobial Resistance among Anaerobic Clinical Isolates

Anaerobic bacteria are normal inhabitants of the human commensal microbiota and play an important role in various human infections. Tedious and time-consuming, antibiotic susceptibility testing is not routinely performed in all clinical microbiology laboratories, despite the increase in antibiotic resistance among clinically relevant anaerobes since the 1990s. β-lactam and metronidazole are the key molecules in the management of anaerobic infections, to the detriment of clindamycin. β-lactam resistance is usually mediated by the production of β-lactamases. Metronidazole resistance remains uncommon, complex, and not fully elucidated, while metronidazole inactivation appears to be a key mechanism. The use of clindamycin, a broad-spectrum anti-anaerobic agent, is becoming problematic due to the increase in resistance rate in all anaerobic bacteria, mainly mediated by Erm-type rRNA methylases. Second-line anti-anaerobes are fluoroquinolones, tetracyclines, chloramphenicol, and linezolid. This review aims to describe the up-to-date evolution of antibiotic resistance, give an overview, and understand the main mechanisms of resistance in a wide range of anaerobes.

Necrotic Enteritis in Broiler Chickens: A Review on the Pathogen, Pathogenesis, and Prevention

Clostridium perfringens type A and C are the primary etiological agents associated with necrotic enteritis (NE) in poultry. The predisposing factors implicated in the incidence of NE changes the physical properties of the gut, immunological status of birds, and disrupt the gut microbial homeostasis, causing an over-proliferation of C. perfringens. The principal virulence factors contributing to the pathogenesis of NE are the α-toxin, β-toxin, and NetB toxin. The immune response to NE in poultry is mediated by the Th1 pathway or cytotoxic T-lymphocytes. C. perfringens type A and C are also pathogenic in humans, and hence are of public health significance. C. perfringens intoxications are the third most common bacterial foodborne disease after Salmonella and Campylobacter. The restrictions on the use of antibiotics led to an increased incidence of NE in poultry. Hence, it is essential to develop alternative strategies to keep the prevalence of NE under check. The control strategies rely principally on the positive modulation of host immune response, nutritional manipulation, and pathogen reduction. Current knowledge on the etiology, pathogenesis, predisposing factors, immune response, effect on the gut microbial homeostasis, and preventative strategies of NE in this post-antibiotic era is addressed in this review.

A rare cause of pneumoperitoneum due to clostridium perfringens in a cirrhotic patient

INTRODUCTION

Abdominal gas gangrene caused by Clostridium perfringens is a rare differential diagnosis to pneumoperitoneum caused by bowel perforation. There are only a handful of case reports on this topic.

PATIENTS AND METHODS

We present the case of a 58 year old cirrhotic patient who represented to our ER after complicated surgery for retroperitoneal liposarcoma. On admission he complained of abdominal pain and mild fever. Due to leukocytosis and CRP a CT scan was performed which showed extensive free air. The patient was taken to the OR for suspected bowel perforation. No perforation could be identified after extensive search and lavage.

RESULTS

Twelve hours after surgery microbiology reported extensive growth of clostridium perfringens in the cultures drawn from ascites. The patient was successfully treated with antibiotics and discharged home soon after.

CONCLUSION

Gas gangrene is a rare differential diagnosis to bowel perforation. Most reported cases are from cirrhotic patients. If no perforation can be identified in the OR postoperative antibiotics should cover clostridium perfringens.

Clinical Differences in Patients Infected with Fusobacterium and Antimicrobial Susceptibility of Fusobacterium Isolates Recovered at a Tertiary-Care Hospital in Korea

Background

Fusobacterium species are obligately anaerobic, gram-negative bacilli. Especially, F. nucleatum and F. necrophorum are highly relevant human pathogens. We investigated clinical differences in patients infected with Fusobacterium spp. and determined the antimicrobial susceptibility of Fusobacterium isolates.

Methods

We collected clinical data of 86 patients from whom Fusobacterium spp. were isolated from clinical specimens at a tertiary-care hospital in Korea between 2003 and 2020. In total, 76 non-duplicated Fusobacterium isolates were selected for antimicrobial susceptibility testing by the agar dilution method, according to the Clinical and Laboratory Standards Institute guidelines (M11-A9).

Results

F. nucleatum was most frequently isolated from blood cultures and was associated with hematologic malignancy, whereas F. necrophorum was mostly prevalent in head and neck infections. Anti-anaerobic agents were more commonly used to treat F. nucleatum and F. varium infections than to treat F. necrophorum infections. We observed no significant difference in mortality between patients infected with these species. All F. nucleatum and F. necrophorum isolates were susceptible to the antimicrobial agents tested. F. varium was resistant to clindamycin (48%) and moxifloxacin (24%), and F. mortiferum was resistant to penicillin G (22%) and ceftriaxone (67%). β-Lactamase activity was not detected.

Conclusions

Despite the clinical differences among patients with clinically important Fusobacterium infections, there was no significant difference in the mortality rates. Some Fusobacterium spp. were resistant to penicillin G, ceftriaxone, clindamycin, or moxifloxacin. This study may provide clinically relevant data for implementing empirical treatment against Fusobacterium infections.

Antimicrobial Susceptibility of Clinical Oral Isolates of Actinomyces spp

Actinomyces species play an important role in the pathogenesis of oral diseases and infections. Susceptibility testing is not always routinely performed, and one may oversee a shift in resistance patterns. The aim of the study was to analyze the antimicrobial susceptibility of 100 well-identified clinical oral isolates of Actinomyces spp. against eight selected antimicrobial agents using the agar dilution (AD) and E-Test (ET) methods. We observed no to low resistance against penicillin, ampicillin-sulbactam, meropenem, clindamycin, linezolid and tigecycline (0-2% ET, 0% AD) but high levels of resistance to moxifloxacin (93% ET, 87% AD) and daptomycin (83% ET, 95% AD). The essential agreement of the two methods was very good for benzylpenicillin (EA 95%) and meropenem (EA 92%). The ET method was reliable for correctly categorizing susceptibility, in comparison with the reference method agar dilution, except for daptomycin (categorical agreement 87%). Penicillin is still the first-choice antibiotic for therapy of diseases caused by Actinomyces spp.

Prevalence and Antimicrobial Resistance of Paeniclostridium sordellii in Hospital Settings

(1) Background: The purpose of this study was to determine the prevalence of clostridia strains in a hospital environment in Algeria and to evaluate their antimicrobial susceptibility to antibiotics and biocides. (2) Methods: Five hundred surface samples were collected from surfaces in the intensive care unit and surgical wards in the University Hospital of Tlemcen, Algeria. Bacterial identification was carried out using MALDI-TOF-MS, and then the minimum inhibitory concentrations (MICs) of various antimicrobial agents were determined by the E-test method. P. sordellii toxins were searched by enzymatic and PCR assays. Seven products intended for daily disinfection in the hospitals were tested against Clostridium spp. spore collections. (3) Results: Among 100 isolates, 90 P. sordellii were identified, and all strains were devoid of lethal and hemorrhagic toxin genes. Beta-lactam, linezolid, vancomycin, tigecycline, rifampicin, and chloramphenicol all proved effective against isolated strains. Among all strains tested, the spores of P. sordellii exhibited remarkable resistance to the tested biocides compared to other Clostridium species. The (chlorine-based 0.6%, 30 min), (glutaraldehyde solution 2.5%, 30 min), and (hydrogen peroxide/peracetic acid 3%, 15 min) products achieved the required reduction in spores. (4) Conclusions: Our hospital’s current cleaning and disinfection methods need to be optimized to effectively remove spores from caregivers’ hands, equipment, and surfaces.

Antimicrobial susceptibility patterns of anaerobic bacteria at an Irish University Hospital over a ten-year period (2010-2020)

OBJECTIVES

In recent years various clinical studies have demonstrated poor outcomes in infections caused by anaerobic bacteria due to inappropriate therapy, directly due to emergence of resistant strains. This is a concern given that many anaerobic infections are treated empirically with metronidazole or a beta-lactam/beta-lactamase inhibitor combinations (e.g., co-amoxiclav, piperacillin-tazobactam). To date there is a paucity of available data on antimicrobial resistance trends of anaerobic bacteria in Ireland, and our study aims to determine such patterns among isolates processed at our institution over the last ten years.

METHODS

Significant anaerobic bacteria isolated from clinical specimens processed at our laboratory from January 2010 to January 2020 inclusive were reviewed. Bacteria were identified using MALDI-TOF, with E-tests used for antimicrobial susceptibility testing. Data was processed through WHONET.

RESULTS

A total of 2098 clinically significant anaerobic bacterial isolates from blood cultures (31%), theatre/intraoperative specimens (30%), aspirates and drain fluid (22%) and wound swabs (17%) were reviewed during the study period; with the majority of isolates being Bacteroides spp (32.79%, n = 688) and Clostridium spp (18.68%, n = 392). With isolates demonstrating well-recognised or inherent resistances excluded, overall resistance to tested antimicrobials was 6.40% to penicillin, 1.71% to metronidazole, 1.43% to co-amoxiclav, 13.63% to clindamycin, 0.43% to piperacillin-tazobactam and 0% to meropenem.

CONCLUSION

Metronidazole and beta-lactam/beta-lactamase inhibitor combinations remain highly efficacious against the majority of anaerobic isolates reviewed, and can safely be used as empiric therapy in suspected anaerobic infections. However, periodic surveillance of resistance trends remains important.

The first case of Veillonella atypica bacteremia in a patient with renal pelvic tumor

We report the first case of bacteremia caused by Veillonella atypica in a morbid elderly female patient who developed obstructive pyelonephritis. She was treated with ceftriaxone and ureteral stenting; this is the first report of V. atypica infection in humans. Species identification was performed by multiplex PCR and sequencing of rpoB. The strain was susceptible to metronidazole and clindamycin but resistant to benzylpenicillin, ampicillin, ampicillin/sulbactam, and moxifloxacin.

Perianal Actinomycosis: A Surgeon's Perspective and Review of Literature

Actinomycosis is a serious suppurative, bacterial infection caused by the gram-positive anaerobic Actinomyces species. Primary perianal actinomycosis is rare and challenging for the colorectal surgeon. We aimed to present our experience and compare this with available literature. All patients with isolated Actinomyces on microbiology reports, between January 2013 and February 2021, were identified and reviewed. Data collection was retrospective based on electronic patient records. The site of infection and treatment strategy were examined. Perianal cases were evaluated in depth. All publications available in the literature were interrogated. Fifty-nine cases of positive actinomycosis cultures were reviewed. Six cases of colonization were excluded. Actinomyces turicensis was the most common organism isolated. Five cases of perianal actinomycosis were identified requiring prolonged antibiotic and surgical therapy. Twenty-one studies, most case reports, published since 1951 were also reviewed. Diagnosis of perianal actinomycosis may be challenging but should be suspected particularly in recurrent cases. Prolonged bacterial cultures in anaerobic conditions are necessary to identify the bacterium. An extended course of antibiotic therapy (months) is required for eradication in certain cases.

Molecular characterization of netB and tpeL virulence factors and antimicrobial resistance genes of Clostridium perfringens isolated from herbs and spices

The present study aimed to determine some virulence-associated genes and antimicrobial multidrug resistance of Clostridium perfringens recovered from herbs and spices widely distributed in the Egyptian market. C. perfringens virulence and resistance factors were determined using PCR targeting the netB, tpeL, ermB, bla and tetK genes. Thirty three out of 392 samples (8.42%) from herbs and spices submitted to our laboratory for bacteriological screening were positive for presence C. perfringens. PCR results for the tpeL gene in isolated C. perfringens revealed 9 out of 33 (27.3 %) of isolates, while netB was not detected. The isolates were resistant to Clindamycin, Vancomycin, tetracycline, and erythromycin with inhibition zones of 6.28 ± 0.63, 8.78 ± 0.41, 9.63 ± 0.63, and 9.84 ± 0.66 mm, respectively. The genes mentioned above were selected to correspond to the ineffective antimicrobials; ermB for erythromycin, tetK for tetracycline, and bla for the remainder. PCR results for antibacterial resistant genes in isolated C. perfringens revealed their presence. From 33 isolates, bla gene was detected in 21 (63.4 %), tetK in 13 (39.4 %) and ermB in only one isolate (3.03 %). Sequencing analysis was done for the bla gene as an example for the detected genes as detected at the highest incidence (63.4%). No cross-relationship was detected upon comparing incidence data of both studied virulence genes and those of antimicrobial resistance. The present findings may explain the resistance of C. perfringens to the examined antibacterials and recommend avoiding the application of them to control the microbe. In addition, the authors recommend following strict hygienic procedures during the industry of herbs and spices to ensure their clearance from Clostridium perfringens before distributing the products as food additives into the markets.

In Vitro Antimicrobial Susceptibility Profiles of Gram-Positive Anaerobic Cocci Responsible for Human Invasive Infections

The aim of this multicentre study was to determine the in vitro susceptibility to anti-anaerobic antibiotics of Gram-positive anaerobic cocci (GPAC) isolates responsible for invasive infections in humans. A total of 133 GPAC isolates were collected in nine French hospitals from 2016 to 2020. All strains were identified to the species level (MALDI-TOF mass spectrometry, 16S rRNA sequencing). Minimum inhibitory concentrations (MICs) of amoxicillin, piperacillin, cefotaxime, imipenem, clindamycin, vancomycin, linezolid, moxifloxacin, rifampicin, and metronidazole were determined by the reference agar dilution method. Main erm-like genes were detected by PCR. The 133 GPAC isolates were identified as follows: 10 Anaerococcus spp., 49 Finegoldia magna, 33 Parvimonas micra, 30 Peptoniphilus spp., and 11 Peptostreptococcus anaerobius. All isolates were susceptible to imipenem, vancomycin (except 3 P. micra), linezolid and metronidazole. All isolates were susceptible to amoxicillin and piperacillin, except for P. anaerobius (54% and 45% susceptibility only, respectively). MICs of cefotaxime widely varied while activity of rifampicin, and moxifloxacin was also variable. Concerning clindamycin, 31 were categorized as resistant (22 erm(A) subclass erm(TR), 7 erm(B), 1 both genes and 1 negative for tested erm genes) with MICs from 8 to >32 mg/L. Although GPACs are usually susceptible to drugs commonly used for the treatment of anaerobic infections, antimicrobial susceptibility should be evaluated in vitro.

A Case of CNS Actinomycosis: Rarer than Rare!

We report a case of cerebral actinomycosis in a 62-year-old male who presented with right-sided weakness and focal convulsions. MRI scan showed a solid intra axial space occupying lesion in the left frontal lobe. Left parietal craniotomy with intra-operative USG guided aspiration and excision of the mass (containing necrotic material) was done. Actinomyces israelii was isolated from the aspirated material. Patient received ceftriaxone and clindamycin for 12 weeks. Physiotherapy and anti-epileptic drugs were continued. On subsequent follow-up visits, his power improved to 5/5 in lower limb, 4/5 in proximal upper limb, 2/5 in distal upper limb. Actinomycosis can cause diverse clinical manifestations, and therefore clinical suspicion is key to diagnosis. Early diagnosis and treatment can lead to good treatment outcomes.

Antimicrobial susceptibility profiles of invasive isolates of anaerobic bacteria from a large Canadian reference laboratory: 2012-2019

Anaerobic bacteria can cause severe and life threatening infections. Susceptibility data are relatively limited on anaerobic organisms despite the clinical importance in guiding empiric treatment of infections. To determine antimicrobial susceptibility profiles of clinically significant anaerobic bacteria, isolates obtained from sterile sites submitted to Public Health Ontario Laboratory (2012-2019) were included in this study (N = 5712). Cefoxitin, clindamycin, metronidazole, meropenem, penicillin and piperacillin-tazobactam were tested using the gradient strip method with MICs interpreted based on Clinical and Laboratory Standards Institute guidelines. Bacteroides spp. (N = 958; 16.7%), Clostridium spp. (N = 798; 14.0%), Cutibacterium spp. (N =659; 11.5%) and Actinomyces spp. (N = 551; 7.0%) were the most commonly isolated genera. Bacteroides fragilis isolates were susceptible to cefoxitin (88.4%), clindamycin (68.4%), metronidazole (96.0%), meropenem (99.0%) and piperacillin-tazobactam (98.4%). Other Bacteroides spp. showed reduced susceptibility to several antimicrobials. Clostridium spp. isolates were susceptible to penicillin (69.7%), clindamycin (69.7%) and cefoxitin (76.3%); C. perfringens and C. ramosum showed distinct susceptibility profiles. Susceptibility rates among anaerobes remained relatively unchanged over 8 years with a few exceptions: C. perfringens susceptibility to clindamycin decreased from 91.3% to 60% (p = 0.03); Clostridium spp. susceptibility to penicillin similarly decreased from 82.1% to 65.9% (p = 0.03); Eggerthella spp. susceptibility to piperacillin-tazobactam decreased from 100% to 24.3% (p < 0.001); B. fragilis group susceptibility to cefoxitin decreased from 70.4% to 48.2% (p = 0.05); and Parabacteroides spp. susceptibility to piperacillin-tazobactam decreased from 100% to 25% (p = 0.01). Our findings underscore the need for ongoing surveillance and periodic monitoring of antimicrobial resistance in order to guide empiric therapy.

Antibiotic resistance pattern of Bacteroides fragilis isolated from clinical and colorectal specimens

BACKGROUND

Bacteroides fragilis is a part of the normal gastrointestinal flora, but it is also the most common anaerobic bacteria causing the infection. It is highly resistant to antibiotics and contains abundant antibiotic resistance mechanisms.

METHODS

The antibiotic resistance pattern of 78 isolates of B. fragilis (22 strains from clinical samples and 56 strains from the colorectal tissue) was investigated using agar dilution method. The gene encoding Bacteroides fargilis toxin bft, and antibiotic resistance genes were targeted by PCR assay.

RESULTS

The highest rate of resistance was observed for penicillin G (100%) followed by tetracycline (74.4%), clindamycin (41%) and cefoxitin (38.5%). Only a single isolate showed resistance to imipenem which contained cfiA and IS1186 genes. All isolates were susceptible to metronidazole. Accordingly, tetQ (87.2%), cepA (73.1%) and ermF (64.1%) were the most abundant antibiotic-resistant genes identified in this study. MIC values for penicillin, cefoxitin and clindamycin were significantly different among isolates with the cepA, cfxA and ermF in compare with those lacking such genes. In addition, 22.7 and 17.8% of clinical and GIT isolates had the bft gene, respectively.

CONCLUSIONS

The finding of this study shows that metronidazole is highly in vitro active agent against all of B. fragilis isolates and remain the first-line antimicrobial for empirical therapy.

Necrotizing Soft Tissue Infections

Necrotizing soft tissue infections occur after traumatic injuries, minor skin lesions, nonpenetrating injuries, natural childbirth, and in postsurgical and immunocompromised patients. Infections can be severe, rapidly progressive, and life threatening. Survivors often endure multiple surgeries and prolonged hospitalization and rehabilitation. Despite subtle nuances that may distinguish one entity from another, clinical approaches to diagnosis and treatment are highly similar. This review describes the clinical and laboratory features of necrotizing soft tissue infections and addresses recommended diagnostic and treatment modalities. It discusses the impact of delays in surgical debridement, antibiotic use, and resuscitation on mortality, and summarizes key pathogenic mechanisms.

Antimicrobial Susceptibility Patterns and Wild-Type MIC Distributions of Anaerobic Bacteria at a German University Hospital: A Five-Year Retrospective Study (2015-2019)

Local antimicrobial susceptibility surveys are crucial for optimal empirical therapy guidelines and for aiding in antibiotic stewardship and treatment decisions. For many laboratories, a comprehensive overview of local antimicrobial susceptibility patterns of anaerobic bacteria is still lacking due to the long incubation time and effort involved. The present study investigates the antimicrobial susceptibility patterns and related clinical and demographic data of 2856 clinical isolates of anaerobic bacteria that were submitted for analysis to the Institute for Medical Microbiology and Hygiene of the Freiburg University Medical Center (a tertiary university medical center in Southern Germany) between 2015 and 2019. Antimicrobial susceptibility testing has been carried out according to the European Committee on Antimicrobial Susceptibility Testing (EUCAST) guideline. Minimum inhibitory concentration (MIC)₅₀ and MIC₉₀ for penicillin, metronidazole, moxifloxacin, and clindamycin were established for Gram-positive anaerobes and for ampicillin-sulbactam, meropenem, metronidazole, moxifloxacin, and clindamycin for Gram-negative anaerobes. The distribution of MIC-values for various antibiotics against anaerobic bacteria was also established, especially for those having no specific breakpoints according to EUCAST guidelines. Most clinically relevant anaerobic bacteria originated from general surgery, neurological, and orthopedic wards. A high proportion of isolates were resistant to moxifloxacin and clindamycin indicating the importance of their susceptibility testing before administration. Based on our study metronidazole and other β-lactam/β-lactamase inhibitor combinations such as ampicillin-sulbactam remain suitable for empirical treatment of infections with anaerobic bacteria.

Atypical Presentation of Periprosthetic Joint Infection After Total Knee Arthroplasty due to Parvimonas micra

There is limited literature reporting the oral pathogen Parvimonas micra as the causative organism of periprosthetic joint infection. Previous reports demonstrate septic arthritis in native or prosthetic joints due to P. micra in elderly or immunocompromised patients associated with tooth abscess and periodontal disease. Our case report is unique because it describes a healthy individual with recurrent gingivitis developing periprosthetic joint infection after total knee arthroplasty as the result of isolated P. micra. Her clinical symptom presented early and manifested as progressive stiffness only. Timely aspiration resulted in early diagnosis, but the patient still underwent 2-stage revision with a more constrained implant. To prevent the risk of infection by oral pathogens such as P. micra, dental history should be thoroughly investigated, and any lingering periodontal infection should be addressed before any arthroplasty operation.

Added-Value of Endometrial Biopsy in the Diagnostic and Therapeutic Strategy for Pelvic Actinomycosis

The particularity of pelvic actinomycosis lies in the difficulty of establishing the diagnosis prior to treatment. The objective of this retrospective bicentric study was to evaluate the pertinence and efficacy of the different diagnostic tools used pre- and post-treatment in a cohort of patients with pelvic actinomycosis. The following data were collected: clinical, paraclinical, type of treatment, and the outcome and pertinence of the two diagnostic methods, bacteriological or histopathological, were evaluated. Twenty-seven women were included, with a pre-treatment diagnosis proposed for 66.7% (n = 18) of them. The diagnosis was established in 13.6% (n = 3) of cases through bacteriological samples, and in 93.8% (n = 15) of cases through histopathological samples, with endometrial biopsy positive in 100% of cases. The treatment was surgical with antibiotics for 55.6% (n = 15) of patients, medical with antibiotic therapy for 40.7% (n = 11) of patients, and surgical without antibiotics for one patient. All patients achieved recovery without recurrence, with a median follow-up of 96 days (4–4339 days). Our study suggested an excellent performance of histopathological analysis, and in particular endometrial biopsy, in the diagnosis of pelvic actinomycosis. This tool allowed early diagnosis and, in some cases, the use of antibiotic therapy alone, making it possible to avoid surgery.

Contemporary Microbiology and Antimicrobial Treatment of Complicated Appendicitis: The Value of a Short-term Study

BACKGROUND

Antimicrobial stewardship interventions to curtail the use of third-generation cephalosporins and antipseudomonal penicillins for the treatment of complicated appendicitis in children are challenging given the tendency to treat complicated disease with broad-spectrum antimicrobials. Reasons for this are unclear, but there is a paucity of contemporary microbiologic data associated with the child presenting with either acute perforated or gangrenous appendicitis. This study aimed to justify the appropriateness of an empiric regimen consisting of ampicillin, tobramycin/gentamicin plus metronidazole and to analyze duration of postoperative therapy.

METHODS

We conducted a retrospective cohort study from February 1, 2017, to October 31, 2018, in children who underwent appendectomy or interventional radiologic drainage for primary complicated appendicitis. The primary outcome was the proportion of patients who had a pathogen isolated from peritoneal fluid culture that was not susceptible to the recommended empiric therapy. The secondary outcomes were the total duration of antimicrobial therapy and the proportion of patients with a postoperative infectious complication within 30 days after intervention.

RESULTS

Of 425 children with primary acute appendicitis, 158 (37%) had complicated appendicitis at presentation. Culture was performed in 53 (40%) of the 133 who underwent a surgical or interventional radiologic intervention. The group with peritoneal cultures was more likely to present with longer symptom duration before admission [3 (interquartile range, 2-5) vs 2 (interquartile range, 1-2) days; P < 0.001] and with purulent peritonitis [47% (25/53) vs 13% (10/80); P < 0.001]. The most common pathogens isolated were anaerobes (81%), Escherichia coli (74%) and Streptococcus anginosus group (62%). Only 4% of isolated bacteria were resistant to empiric therapy. Postoperative infectious complications were documented in 23 (17%) patients and were not associated with the presence of a resistant pathogen or the choice of antimicrobial agents but with more severe disease and higher C-reactive protein values (303 vs 83 mg/L; P=0.03) at presentation.

CONCLUSIONS

In a cohort of previously healthy children presenting with complicated appendicitis requiring surgical drainage, the most common bacteria from peritoneal cultures continue to be S. anginosus, aminoglycoside-susceptible Gram-negative bacilli and anaerobes. In an attempt to reduce extended-spectrum cephalosporin use, these data were useful in supporting the use of metronidazole with ampicillin and an aminoglycoside, rather than third-generation cephalosporins.

Antimicrobial susceptibility surveillance of obligate anaerobic bacteria in the Kinki area

Obligate anaerobes exist as resident flora in various sites in humans, but they are also emphasized as endogenous causative microorganism of infections. We performed surveillance to understand the trend of drug susceptibility in obligate anaerobic bacteria in the Kinki area of Japan. In the experiment, we used 156 obligate anaerobe isolates collected from 13 institutions that participated in the Study of Bacterial Resistance Kinki Region of Japan. MALDI Biotyper was used to identify the collected strains, and among the 156 test strains, those that could be identified with an accuracy of Score Value 2.0 or more included 6 genera, 30 species, and 144 strains (Bacteroides spp. 77 strains, Parabacteroides sp. 2 strains, Prevotella spp. 29 strains, Fusobacterium spp. 14 strains, Porphyromonas spp. 2 strains, and Clostridioides difficile 20 strains), and they were assigned as subject strains for drug susceptibility testing. The drug susceptibility test was carried out by broth microdilution method using Kyokuto Opt Panel MP ANA (Kyokuto Pharmaceutical Industrial Co., Ltd., Tokyo, Japan) and judged according to CLSI criteria. As a result, Bacteroides and Parabacteroides species showed good sensitivities to tazobactam-piperacillin, imipenem, metronidazole and chloramphenicol, and low sensitivities to ampicillin, cefoperazone and vancomycin. Prevotella species showed good sensitivities to sulbactam-ampicillin, tazobactam-piperacillin, cefmetazole, imipenem, doripenem and metronidazole. Susceptibility rates to other drugs were slightly different depending on the bacterial species. Both Fusobacterium spp. and Porphyromonas spp. showed high sensitivities to many drugs. C. difficile was highly sensitive to vancomycin and metronidazole, having MIC₉₀s of 0.5 μg/mL and ≤2 μg/mL, respectively.

Antimicrobial susceptibility against metronidazole and carbapenem in clinical anaerobic isolates from Pakistan

Background

Globally metronidazole and carbapenem resistance in anaerobic organisms is increasing necessitating continuous surveillance to guide selection of empirical treatment. In this study we have determined metronidazole resistance in anaerobes using MIC Evaluator strips (M.I.C.E strips). Carbapenem resistance was evaluated only in metronidazole resistant isolates.

Material and methods

The study was conducted at the Aga Khan University (AKU) Hospital laboratory, Karachi, Pakistan (2014–2017). Metronidazole and imipenem resistance was evaluated using M.I.C.E strips and minimum inhibitory concentrations (MICs) were interpreted using Clinical Laboratory Standards Institute (CLSI) criteria. Clinical details including demographics, prolonged hospital stay, malignancy, transplant, dialysis, diabetes, site of infection and outcome were analyzed for association with metronidazole resistance.

Results

Of the 223 clinically significant isolates, 39 (17.5%) were metronidazole resistant (excluding the inherently resistant organisms; for example Cutibacterium species). Imipenem resistance was determined in 29 metronidazole resistant isolates and of these 7 (24.1%) were found to be resistant. Proportion of metronidazole resistant strains was highest amongst Bacteroides species. A significant increase in metronidazole resistance from 12.3% in 2010–2011 to 17.5% in the current study was found. Carbapenem resistance also emerged in the period 2014–2017.

Isolates from malignancy and transplant patients showed lower odds of developing metronidazole resistance (0.003(95% CI: 1.7–17.9)). Prolonged hospital stay was not associated with metronidazole resistance (1.1((95% CI: 0.5–2.5)).

Conclusion

The rising trend of metronidazole resistance and emergence of carbapenem resistance in anaerobic bacteria is alarming. Continued surveillance with strengthening of laboratory capacity regarding anaerobic susceptibility testing is urgently needed in Pakistan.

Diagnosis and Management of a Cryptoglandular Actinomycotic Fistula-in-Ano: An Update on 7 New Cases and a Review of the Literature

Purpose

Primary anal actinomycosis of cryptoglandular origin, a rare cause of anal suppurative disease, requires specific management to be cured. The aims of this retrospective study were to describe clinical, morphological, and microbiological features of this entity and to evaluate management practices for new cases observed since 2001.

Methods

This was a retrospective case series conducted at the Diaconesses-Croix Saint-Simon Hospital in Paris.

Results

From January 2001 to July 2016, 7 patients, 6 males and 1 female (median, 49 years), presenting with an actinomycotic abscess with a cryptoglandular anal fistula were included for study. The main symptom was an acute painful ischioanal abscess. One patient exhibited macroscopic small yellow granules (“sulfur granules”), another “watery pus” and a third subcutaneous gluteal septic metastasis. All patients were overweight (body mass index ≥ 25 kg/m²). Histological study of surgically excised tissue established the diagnosis. All the patients were managed with a combination of classical surgical treatment and prolonged antibiotic therapy. No recurrence was observed during follow-up, the median follow-up being 3 years.

Conclusion

Actinomycosis should be suspected particularly when sulfur granules are present in the pus, patients have undergone multiple surgeries or suppuration has an unusual aspect. Careful histological examination and appropriate cultures of pus are needed to achieve complete eradication of this rare, but easily curable, disease.

Identification of CfiA coding genes in Bacteroides fragilis isolates recovered in Argentina. Inconsistencies in CfiA organization and nomenclature

CfiA (CcrA) metallo-β-lactamase is the main carbapenem resistance mechanism in B. fragilis. From cfiA positive isolates detected in a previous surveillance study, 3 displayed resistance to imipenem while the remaining were susceptible. The aim of this study was to identify the cfiA alleles and to analyze the presence of IS elements in their upstream regions. CfiA-1, CfiA-4, CfiA-13, CfiA-19 and CfiA-22 were detected. IS elements belonging to IS21 family and IS942 group were identified upstream to cfiA in the 3 imipenem resistant isolates. We present an exhaustive analysis of cfiA/CfiA registers in databases, illustrating the inconsistencies in both organization and nomenclature. According to this analysis CfiA family comprises nowadays 15 different CfiA variants coded by 24 cfiA sequences. Curation of CfiA database is mandatory, if not new cfiA admission at GenBank will contribute to make this classification more complex.

Genetic identification and antimicrobial susceptibility of clinically isolated anaerobic bacteria: A prospective multicenter surveillance study in Japan

This prospective multicenter surveillance study was designed to provide antimicrobial susceptibility profiles of clinical anaerobic bacteria with genetic species identification in Japan. In 2014, a total of 526 non-duplicate clinical anaerobic isolates were collected from 11 acute-care hospitals in the Kyoto and Shiga regions of Japan. Genetic identification was performed using 16S rRNA sequencing. Minimum inhibitory concentrations were determined in the central laboratory and were interpreted using the CLSI criteria. Genetic analysis provided species-level identification for 496 isolates (83 species in 40 genera) and genus-level identification for 21 isolates (13 genera). Among these 517 isolates, the most frequent anaerobes were Bacteroides spp. (n = 207), Prevotella spp. (n = 43), Clostridium spp. (n = 40), and Peptoniphilus spp. (n = 40). B. fragilis was the most common species (n = 107) and showed 91.6%-97.2% susceptibility to β-lactam/β-lactamase inhibitor combinations (BLBLIs; ampicillin-sulbactam, amoxicillin-clavulanate, and piperacillin-tazobactam) and carbapenems (imipenem and meropenem) as well as 100% susceptibility to metronidazole. Gram-negative anaerobes were highly susceptible to metronidazole (99.0%) followed by BLBLIs and carbapenems (>90% each). BLBLIs or carbapenems also retained activity against Gram-positive anaerobes (99.5%-100%) except Clostridioides difficile. All isolates were susceptible to combinations of metronidazole with BLBLIs or carbapenems. Thus, BLBLIs or carbapenems are first choices for empirical therapy of anaerobic infections in Japan, and these antimicrobials in combination with metronidazole should be reserved for very severe infections and targeted therapy.

Systemic Metronidazole May Not Reduce Posthemorrhoidectomy Pain: A Meta-Analysis of Randomized Controlled Trials

BACKGROUND

Hemorrhoidectomy is associated with significant postoperative pain. Oral metronidazole has been recommended as an adjunct to improve posthemorrhoidectomy analgesia.

OBJECTIVE

This study aimed to evaluate the impact of oral metronidazole on patient-reported pain following hemorrhoidectomy.

DATA SOURCES

We conducted a systematic search in the MEDLINE, EMBASE, ISI Web of Science, and Cochrane Central Register of Controlled Trials databases.

STUDY SELECTION

Randomized controlled trials examining adults who underwent surgical hemorrhoidectomy were included. Participants in an active intervention group received oral metronidazole postoperatively, and those in a control group received placebo or usual care. Postoperative pain was assessed for at least 3 days postoperatively.

INTERVENTION

A random-effects model was used.

MAIN OUTCOMES MEASURES

The primary outcome was pain during the first 2 postoperative weeks, measured on a visual analogue scale. The secondary outcome was time to return to normal activities.

RESULTS

Patients who received oral metronidazole had significantly lower reported pain scores on postoperative day 1 (standardized mean difference, -0.87 ± 0.44; 95% CI, -1.73 to -0.015; p = 0.046; n = 4) and day 4 (standardized mean difference, -1.43 ± 0.71; 95% CI, -2.83 to -0.037; p = 0.044; n = 3). Metronidazole use was associated with a significantly shorter time to return to normal activities (standardized mean difference, -0.76 ± 0.34; 95% CI, -1.43 to -0.088, p = 0.027). The improvements disappeared in a sensitivity analysis excluding the largest trial with a high risk of bias, and no significance was observed during the remaining postoperative days.

LIMITATIONS

The meta-analysis was limited by lack of double blinding, absence of a placebo, and unclear or high risk of bias in a proportion of the included trials.

CONCLUSIONS

Although a favorable adverse effect profile supports consideration of oral metronidazole to reduce posthemorrhoidectomy pain, pooled analysis reveals inconsistent results with no pain reduction on most postoperative days. The current recommendation for routine prescription of oral metronidazole should be reevaluated in the absence of additional well-designed trials.

Water Sources in a Zoological Park Harbor Genetically Diverse Strains of Clostridium Perfringens Type A with Decreased Susceptibility to Metronidazole

The presence of Clostridium perfringens in water is generally regarded as an indicator of fecal contamination, and exposure to waterborne spores is considered a possible source of infection for animals. We assessed the presence and genetic diversity of C. perfringens in water sources in a zoological park located in Madrid (Spain). A total of 48 water samples from 24 different sources were analyzed, and recovered isolates were toxinotyped, genotyped by fluorophore-enhanced repetitive polymerase chain reaction (rep-PCR) fingerprinting and tested for antimicrobial susceptibility. C. perfringens was recovered from 43.8 % of water samples and 50 % of water sources analyzed. All isolates (n = 70) were type A and 42.9 % were β2-toxigenic (i.e., cpb2+), but none contained the enterotoxin-encoding gene (cpe). Isolates belonged to 15 rep-PCR genotypes and most genetic diversity (88 %) was distributed among isolates obtained from the same sample. Most isolates displayed intermediate susceptibility (57.1 %; MIC = 16 μg ml^-1) or resistance (5.7 %; MIC ≥ 32 μg ml^-1) to metronidazole. No resistance to other antimicrobials was detected, although some isolates showed elevated MICs to erythromycin and/or linezolid. Finally, a marginally significant association between absence of cpb2 and decreased susceptibility to metronidazole (MIC ≥ 16 μg ml^-1) was detected. In conclusion, our results reveal a high prevalence of C. perfringens type A in the studied water reservoirs, which constitutes a health risk for zoo animals. The elevated MICs to metronidazole observed for genetically diverse isolates is a cause of additional concern, but more work is required to clarify the significance of reduced metronidazole susceptibility in environmental strains.

Heterogeneity in resistant fecal Bacteroides fragilis group collected from healthy people

Normal nonpathogenic flora would represent a constant lake of resistance genes potentially transferable to human pathogens. To assess the prevalence of resistance genes and genetic variability of Bacteroides fragilis group (BFG) from normal flora, 177 Bacteroides isolates obtained from the fecal samples of healthy individuals. These isolates were subjected to antibiotic susceptibility testing and pulsed field gel electrophoresis (PFGE). The isolates were further tested for the presence of ermF, tetQ and bft genes by PCR. Our results indicated the presence of different clonal strains (1 common type and 57 single types) among the resistant isolates. The resistance rate for the six antibiotics in this study was between 1% and 95%. Most of the isolates (99%) were susceptible to metronidazole. ermF and tetQ were detected in all erythromycin and tetracycline resistant isolates. None of the isolates were carried bft gene. These data suggest dissemination of heterogenic clonal groups in healthy persons and resistance to 5 high commonly used antibiotics.

Clinical characteristics associated with mortality of patients with anaerobic bacteremia

The presence of anaerobes in the blood stream is known to be associated with a higher rate of mortality. However, few prognostic risk factor analyses examining whether a patient's background characteristics are associated with the prognosis have been reported. We performed a retrospective case-controlled study to assess the prognostic factors associated with death from anaerobic bacteremia. Seventy-four patients with anaerobic bacteremia were treated between January 2005 and December 2014 at Aichi Medical University Hospital. The clinical information included drug susceptibility was used for analysis of prognostic factors for 30-day mortality. Multivariate logistic analyses revealed an association between the 30-day mortality rate and malignancy (OR: 3.64, 95% CI: 1.08-12.31) and clindamycin resistance (OR: 7.93, 95% CI: 2.33-27.94). The result of Kaplan-Meier analysis of mortality showed that the 30-day survival rate was 83% in clindamycin susceptible and 38.1% in clindamycin resistant anaerobes causing bacteremia. The result of log-rank test also showed that susceptibility to clindamycin affected mortality (P < 0.001). Our results indicated that malignancy and clindamycin susceptibility could be used to identify subgroups of patients with anaerobic bacteremia with a higher risk of 30-day mortality. The results of this study are important for the early and appropriate management of patients with anaerobic bacteremia.

First Report ofClostridium lavalenseIsolated in Human Blood Cultures

An 88-year-old man was admitted to the hospital with worsening malaise, fever, and weakness. Anaerobic blood culture bottles revealed the presence of an anaerobic, Gram-positive sporulated bacillus. Empirical antibiotherapy with intravenous piperacillin-tazobactam was initiated. The patient defervesced after four days and was switched to oral amoxicillin on his 6th day of antibiotic therapy and later discharged from the hospital. Four months later, he had recovered. The bacterium was initially identified as Clostridium butyricum using anaerobic manual identification panel. 16S rRNA gene sequence and phylogenetic analysis showed the bacterium to be Clostridium lavalense, a recently described species with no previously published case of isolation in human diagnostic samples so far. This is the first report of Clostridium lavalense isolation from human blood cultures. Further studies are needed in order to elucidate the role of Clostridium lavalense in human disease and its virulence factors.

Resistance patterns in clinical isolates of pathogenic Actinomyces species

OBJECTIVES

Actinomyces spp. are commensals that may occasionally invade deep tissue structures, causing difficult-to-treat and disfiguring lesions. Information on antimicrobial resistance patterns is limited to observations from two previous studies. Therefore, we examined antimicrobial resistance patterns in clinical isolates of Actinomyces spp.

METHODS

In this retrospective assessment of antimicrobial resistance patterns, we identified 392 Actinomyces spp. at a tertiary care centre from January 2008 to December 2014. MICs of various antimicrobial agents, including ampicillin/sulbactam, meropenem, clindamycin, metronidazole and vancomycin for anaerobic actinomycetes, were obtained by Etest. For aerobic actinomycetes, imipenem, cefotaxime, amikacin, linezolid, moxifloxacin, trimethoprim/sulfamethoxazole and clarithromycin were tested. MIC results were interpreted based on guidelines published by the CLSI (formerly NCCLS).

RESULTS

Actinomyces meyeri was predominantly isolated and accounted for 34% of all Actinomyces spp. identified, followed by Actinomyces turicensis with 23%. Actinomyces neuii is considered to be a rare Actinomyces sp., but accounted for 8% of isolates. Antimicrobial susceptibility testing of isolates showed that the Actinomyces spp. were almost uniformly susceptible to β-lactam antimicrobials (with and without β-lactamase inhibitors), carbapenems, tetracyclines and vancomycin. In contrast, Actinomyces spp. isolates were almost uniformly resistant to metronidazole.

CONCLUSIONS

β-Lactam antimicrobial agents remain the first choice, whereas metronidazole should be avoided, in the treatment of actinomycosis. Reasonable alternatives for treatment are tetracyclines and carbapenems.

Delayed infection with Parvimonas micra following spinal instrumentation

BACKGROUND CONTEXT

Delayed-onset surgical site infections following spinal instrumentation are uncommon and often present with chronic pain and implant failure. Anaerobic organisms are rarely implicated and identified with difficulty in these infections.

PURPOSE

We report a case of vertebral osteomyelitis and epidural abscess due to Parvimonas micra, an anaerobic bacterium, six months following spinal instrumentation.

STUDY DESIGN/SETTING

Case Report.

RESULTS

P. micra was identified from multiple intraoperative tissue and hardware specimens. With hardware explant and antibiotic therapy, the patient had a successful outcome.

CONCLUSIONS

To our knowledge, this is the first report of a P. micra hardware-associated spinal infection.

Fusobacterial head and neck infections in children

Fusobacterium species are increasingly recognized as a cause of head and neck infections in children. These infections include acute and chronic otitis, sinusitis, mastoiditis, and tonsillitis; peritonsillar and retropharyngeal abscesses; Lemierre syndrome; post-anginal cervical lymphadenitis; and periodontitis. They can also be involved in brain abscess and bacteremia associated with head and neck infections. This review describes the clinical spectrum of head and neck fusobacterial infection in children and their management.

Bacteremic meningitis caused by Parvimonas micra in an immunocompetent host

A 61-year-old man with chronic hepatitis B and dyslipidemia visited the emergency department with a fever and severe headache. He was diagnosed with bacterial meningitis after a lumbar puncture, and blood culture revealed Parvimonas micra bacteremia. Although he had a history of extraction of a molar two weeks before symptom onset, there was no evidence of abscess formation on physical examination or imaging studies. He was successfully treated with oral metronidazole for 12 days after 9 days of treatment with IV ceftriaxone and vancomcycin. This is the first report of primary bacterial meningitis caused by this organism, which indicates that this organism is capable of being a bacterial meningitis pathogen.