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.

Anaerobic infections in patients admitted in various surgical units of a tertiary care hospital of north India: neglected but important

Background and Objectives: Anaerobic infections are usually caused by the host’s endogenous flora due to a breach in the anatomical barriers and Bacteroides spp. are the most notorious organisms associated with anaerobic infections. The identification of anaerobes has been a challenge since times. MALDI-TOF-MS is a boon for aiding the rapid detection of anaerobic organisms and has helped us to enlist the distribution of various anaerobic pathogens. Materials and Methods: This retrospective analysis (January 2018 to December 2019) was carried out in a tertiary care hospital in North India, in which the anaerobic microbiological profile of all patients admitted to surgical wards, ICU, and OPD of various departments (Orthopedics, Surgery, Gynecology, and Obstetrics) was reviewed. Samples received were immediately processed aerobically (5% sheep blood agar and Mac Conkeyagar) as well as anaerobically (RCM and freshly prepared sheep blood agar) as per the laboratory protocols. Results: Bacteroides fragilis (19.12%) was the most common anaerobe whereas among aerobes Escherichia coli (30.2%) followed by Klebsiella pneumoniae (10.34%) were most commonly isolated. The majority of patients were males (56%) and the most common presentation was with abscesses (21.4%). Polymicrobial infections (69.51%) outnumbered monomicrobial ones (30.48%). Conclusion: There is a paucity of literature on anaerobe isolation from surgical infections from our country which motivated us to study anaerobic infections and the high sample size in our institute enabled us to study surgical infections from an anaerobic perspective. This will add to the knowledge of microbiologists and clinicians. MALDI-TOF MS helped in rapid and accurate identification and hence we could report a wider spectrum of organisms in our study

The Concentration of Metronidazole in the Distal Interphalangeal Joint following Intravenous Regional Limb Perfusion via the Cephalic Vein in Standing Horses

Objective The aim of this study was to determine the concentration of metronidazole in the distal interphalangeal joint (DIPJ) of the thoracic limb after administering metronidazole to standing horses by intravenous regional limb perfusion (IVRLP). Methods Eleven healthy horses had a wide rubber tourniquet applied to the proximal aspect of the antebrachium for 0.5 hours and 500 mg of metronidazole diluted in physiologic saline solution to a total volume of 108 mL was administered by cephalic IVRLP. Synovial fluid samples were collected from the DIPJ before perfusion and at 0.25, 0.5, 2, 12 and 24 hours. Blood samples were obtained at the same time points for serum analysis. Concentrations of metronidazole were determined by liquid chromatography/tandem mass spectrometry. Results Four horses were excluded due to low synovial fluid concentrations and not completing the full tourniquet application time. The C max in the synovial fluid was 327 ± 208 µg/mL, and the t max was 26 ± 7 minutes. Only the concentrations of metronidazole at time points 0.25 and 0.5 hours were significantly different (p < 0.001) from synovial concentration before perfusion. The serum C max was 1.78 ± 0.93 µg/mL, and the t max was 76 ± 52min. Conclusion Metronidazole administered by IVRLP reached high concentrations in the synovial fluid at 0.5 hours. However, the concentrations rapidly decreased below the minimum inhibitory concentration of potential target pathogens. Effectiveness of metronidazole administered by IVRLP as a sole therapy against anaerobic infections of synovial structures of the distal limb cannot be determined by a pharmacokinetic study. However, the present study serves as the basis for future carefully planned clinical trials.

MONITORING OF ANAEROBIC PATHOGENS RESISTANCE IN PATIENTS WITH SURGICAL SKIN AND SOFT TISSUE INFECTIONS

Background: The problem of treating anaerobic infections in surgery continues to be relevant. Aim: To develop a protocol for empirical antibiotic therapy of anaerobic infection in patients with surgical skin and soft tissue infections. Material and methods: A total of 191 patients were examined. Identification and assessment of pathogens sensitivity was performed on the АТВ Expression analyzer. In addition, we used the ID-ANA and AB-AN test systems, developed by us. Results: In the structure of anaerobes, bacteroids, peptococci and peptostreptococci continue to occupy the leading positions. No changes in the resistance of anaerobes to most antibiotics were found. There is an increase in the resistance of peptococci and peptostreptococci to clindamycin. Metronidazole, imipenem, meropenem retain high activity. Conclusions: If anaerobic infection is suspected, it is recommended to prescribe metronidazole, and imipenem and meropenem as reserve drugs.

Improving the Solubility, Dissolution, and Bioavailability of Metronidazole via Cocrystallization with Ethyl Gallate

Metronidazole (MTZ) is an antibacterial drug widely used for the treatment of protozoan and anaerobic infections in humans and animals. However, its low bioavailability necessitates the frequent administration of a high dose to attain an effective plasma concentration profile for therapy. To reduce the dose of MTZ, we have prepared a new cocrystal between MTZ and ethyl gallate (EG). The solid-state properties of MTZ-EG were characterized using complimentary techniques, including thermal, spectroscopic, microscopic, and X-ray crystallographic methods. The MTZ-EG cocrystal exhibits a higher solubility and faster dissolution than MTZ. The bioavailability of MTZ in rats was increased by 36% when MTZ-EG was used.

Use of ornidazole in the treatment of anaerobic infection in surgery

One of the most complex problems of modern surgery is the treatment and prevention of anaerobic infection. Main place in overcoming of this infectious complication is devoted to urgent surgical intervention and correct early empiric antibacterial therapy. Special place in the combined empiric antibacterial treatment is devoted to 5-nitroimidazoles. Modern data about clinical efficacy of ornidazole in the treatment of surgical infectious complications is presented in the article. We performed a comparison of therapeutic activity and physical-chemical properties, pharmacokinetic and pharmacodynamic features of ornidazole with the first representative of 5-nitroimidazole class – metronidazole. Taking into account antiprotozoal and antianaerobic activity of ornidazole, it is recommended to be used in the schemes of combined therapy of severe generalized anaerobic infections and purulent processes of different localization; treatment and prevention of surgical infections after intraabdominal, thoracic, proctological and dental surgical interventions.

The Prevalence and Clinical Significance of Anaerobic Bacteria in Major Liver Resection

(1) Background: Anaerobic infections in hepatobiliary surgery have rarely been addressed. Whereas infectious complications during the perioperative phase of liver resections are common, there are very limited data on the prevalence and clinical role of anaerobes in this context. Given the risk of contaminated bile in liver resections, the goal of our study was to investigate the prevalence and outcome of anaerobic infections in major hepatectomies. (2) Methods: We retrospectively analyzed the charts of 245 consecutive major hepatectomies that were performed at the department of General, Visceral, and Transplantation Surgery of the University Hospital of Tuebingen between July 2017 and August 2020. All microbiological cultures were screened for the prevalence of anaerobic bacteria and the patients’ clinical characteristics and outcomes were evaluated. (3) Results: Of the 245 patients, 13 patients suffered from anaerobic infections. Seven had positive cultures from the biliary tract during the primary procedure, while six had positive culture results from samples obtained during the management of complications. Risk factors for anaerobic infections were preoperative biliary stenting (p = 0.002) and bile leaks (p = 0.009). All of these infections had to be treated by intervention and adjunct antibiotic treatment with broad spectrum antibiotics. (4) Conclusions: Anaerobic infections are rare in liver resections. Certain risk factors trigger the antibiotic coverage of anaerobes.

Fusobacterium Nucleatum : An Atypical Cause of Pyogenic Liver Abscess in an Apparently Immunocompetent Patient

Pyogenic liver abscess is an uncommon but potentially lethal infection if left untreated. Enteric bacteria and anaerobes are the most common causative organisms of pyogenic liver abscess. Although most infections are of a polymicrobial nature, monomicrobial infections are possible. An immunocompromised status and the presence of periodontal disease are the risk factors for liver abscess caused by these rare, monomicrobial anaerobic infections. Here, we report on a successful non-operative management of a case of multiloculated pyogenic liver abscess caused by Fusobacterium nucleatum in a young, healthy, immunocompetent male patient. The diagnosis was established by radiological imaging and was based on a positive aspirate culture, whereas the mainstay of treatment comprised percutaneous drainage and a prolonged course of antibiotics. Thus, the patient was successfully treated with a 2-week course of intravenous imipenem/cilastatin while he was on percutaneous drainage, and he is now doing well.