Antimicrobial susceptibility pattern of oral gram negative anaerobes from Indian subjects.

OBJECTIVES: There is paucity of information on the antimicrobial susceptibility pattern of oral anaerobic bacteria. In this study, an attempt has been made to evaluate the antimicrobial susceptibility/resistance trend of oral Gram negative bacteria from Indian subjects. METHODS: Minimum inhibitory concentrations (MIC) of 304 isolates against twelve different antibiotics were determined using gradient diffusion MIC strips. The organisms were isolated and identified based on phenotypic characteristics and included Porphyromonas gingivalis, Prevotella species, Tannerella forsythia, Fusobacterium nucleatum, Aggregatibacter actinomycetemcoitans, Eickenella corrodens and Capnocytophaga species. For each antimicrobial agent, MIC50 and MIC90 were calculated and expressed. RESULTS: Resistance to azithromycin, clindamycin, and amoxicillin was observed in most of the anaerobic bacterial species studied. High degree of susceptibility was observed to amoxillin-clavulanic acid, doxycycline and moxifloxacin. A single strain of P. melaninogenica was resistant to moxifloxacin. The susceptibility pattern varied with cephalosporins among species. Ceftriaxone showed highest and cefazolin least efficacy among cephalosporins. All anaerobic bacteria tested were susceptible to metronidazole. Strains of T. forsythia were more resistant to several antibiotics than other anaerobic bacteria. All three species of capnophilic bacteria displayed high degree of resistance to metronidazole and significant resistance to amoxicillin, azithromycin, clindamycin, cefazolin and cefuroxime. CONCLUSIONS: Amoxicillin-clavulanic acid, doxycycline, moxifloxacin and metronidazole appeared to be the most effective drugs against gram negative anaerobic bacteria. However, the MIC50 and MIC90 values against metronidazole were on the higher side of the normal indicating a potential for developing resistance.

Surveillance of antimicrobial resistance in recent clinical isolates of Gram-negative anaerobic bacteria in a Greek University Hospital.

The aim of our study was to determine the antimicrobial susceptibility profiles of 267 Gram-negative clinically significant anaerobes, isolated between October 2016 and October 2019, in a Greek university hospital. The species identification was performed by conventional methods and using the Vitek 2 automated system. Antimicrobial susceptibility testing to determine the MICs was performed by the E-test method. The antimicrobial agents tested were penicillin, ampicillin, amoxicillin-clavulanic acid, piperacillin-tazobactam, cefoxitin, imipenem, meropenem, clindamycin, metronidazole, moxifloxacin, chloramphenicol and tigecycline. The results were interpreted using the CLSI and FDA breakpoints. The majority of the isolates belonged to Bacteroides fragilis group (58.8%), followed by Prevotella spp. (23.2%), Fusobacterium spp. (11.2%) and Veillonella spp. (6.4%). The most prevalent types of infection were skin and soft tissue infections (34.8%), and inta-abdomonal infections (29.6%). Among all isolates tested, the lowest rates of resistance (<5%) were detected to carbapenems, metronidazole, chloramphenicol and tigecycline. Resistance to piperacillin-tazobactam was observed in 5.4%, 24.6%, 3.3% and 17.6%, of B. fragilis, B. fragilis group, Fusobacterium spp. and Veillonella spp. isolates, respectively. Although a high prevalence of resistance to clindamycin, cefoxitin, and moxifloxacin, was detected particularly among members of the B. fragilis group, cefoxitin resistance was low for Prevotella spp. (3.2%), Fusobacterium spp. (3.3%) and Veillonella spp. (0%). Our findings underscore the need for periodic monitoring of antimicrobial resistance in order to guide empirical therapy.

Mechanistic insights into the action of probiotics against bacterial vaginosis and its mediated preterm birth: An overview.

The human body is a reservoir of numerous micro-creatures; whose role is substantial and indispensable in the overall development of human beings. The advances in omic approaches have offered powerful means to decipher the core microbiome and metabolome diversities in a specific organ system. The establishment of lactobacilli in the female reproductive tract is thought to be a paramount prerequisite that maintains homeostatic conditions for a sustainable and healthy pregnancy. Nevertheless, a plethora of such Lactobacillus strains of vaginal source revealed probiotic phenotypes. The plummeting in the occurrence of lactobacilli in the vaginal ecosystem is associated with several adverse pregnancy outcomes (APOs). One such pathological condition is "Bacterial Vaginosis" (BV), a pathogen dominated gynecological threat. In this scenario, the ascending traffic of notorious Gram-negative/variable BV pathogens to the uterus is one of the proposed pathways that give rise to inflammation-related APOs like preterm birth. Since antibiotic resistance is aggravating among urogenital pathogens, the probiotics intervention remains one of the alternative biotherapeutic strategies to overcome BV and its associated APOs. Perhaps, the increased inclination towards the safer and natural biotherapeutic strategies rather than pharmaceutical drugs for maintaining gestational and reproductive health resulted in the use of probiotics in pregnancy diets. In this context, the current review is an attempt to highlight the microbiome and metabolites signatures of BV and non-BV vaginal ecosystem, inflammation or infection-related preterm birth, host-microbial interactions, role and effectiveness of probiotics to fight against aforesaid diseased conditions.

Aerobic bacteriological profile and antimicrobial susceptibility pattern of pus isolates from tertiary care hospital in India.

INTRODUCTION: Pyogenic infections are an important cause of sepsis. These infections are difficult to treat because of the pathogens with increasing antibiotic resistance. It is important to know the pathogens causing the infections and its antibiotic susceptibility for proper management of the patients. METHODOLOGY: A retrospective analysis of 1428 culture positive pus and tissue samples received in the department of microbiology from various departments in the hospital between January 2012 to 2017 was performed. Data regarding the pathogen isolated and its antimicrobial susceptibility were collected and analyzed. The specimens were primarily processed, as per standard methods. Identification and susceptibility testing was done using the Vitek-2C system. RESULTS: Among the samples males outnumbered females (M: F-2.5:1) and the median age was 47 years. The total number of patients were 1428 with total number of isolates being 1525 as in our study monomicrobial infections were seen in 93.2% (1331/1428) patients whereas combined infections with growth of two pathogens in 6.8% (97/1428). Gram-negative bacilli were isolated in 68.3% (1042/1525). Among the Gram-negative bacilli Escherichia coli was the major pathogen isolated (38.6%, 403/1042). Gram positive organisms were isolated in 31.6% (483/1525) of cases and Staphylococcus aureus was the predominant organism isolated (91.7%, 443/483). Rare pathogens like Burkholderia pseudomallei in 3 patients and Nocardia in one patient were also isolated. CONCLUSION: This study emphasizes to understand the common organisms isolated from wound infections and it helps in empirical treatment of patients based on antibiotic susceptibility patterns.

Low antibiotic resistance among anaerobic Gram-negative bacteria in periodontitis 5 years following metronidazole therapy.

The objective of this study was to assess antibiotic susceptibility among predominant Gram-negative anaerobic bacteria isolated from periodontitis patients who 5 years prior had been subject to mechanical therapy with or without adjunctive metronidazole. One pooled sample was taken from the 5 deepest sites of each of 161 patients that completed the 5 year follow-up after therapy. The samples were analyzed by culture. A total number of 85 anaerobic strains were isolated from the predominant subgingival flora of 65/161 patient samples, identified, and tested for antibiotic susceptibility by MIC determination. E-tests against metronidazole, penicillin, amoxicillin, amoxicillin + clavulanic acid and clindamycin were employed. The 73/85 strains were Gram-negative rods (21 Porphyromonas spp., 22 Prevotella/Bacteroides spp., 23 Fusobacterium/Filifactor spp., 3 Campylobacter spp. and 4 Tannerella forsythia). These were all isolated from the treated patients irrespective of therapy procedures (+/-metronidazole) 5 years prior. Three strains (Bifidobacterium spp., Propionibacterium propionicum, Parvimonas micra) showed MIC values for metronidazole over the European Committee on Antimicrobial Susceptibility Testing break point of >4 µg/mL. All Porphyromonas and Tannerella strains were highly susceptible. Metronidazole resistant Gram-negative strains were not found, while a few showed resistance against beta-lactam antibiotics. In this population of 161 patients who had been subject to mechanical periodontal therapy with or without adjunct metronidazole 5 years prior, no cultivable antibiotic resistant anaerobes were found in the predominant subgingival microbiota.

First Case Report of Bacteremia Due to Catabacter hongkongensis in a Korean Patient

No abstract available.

In-vitro activity of solithromycin against anaerobic bacteria from the normal intestinal microbiota.

Solithromycin is a novel fluoroketolide with high activity against bacteria associated with community-acquired respiratory tract infections as well as gonorrhea. However, data on the activity of solithromycin against anaerobic bacteria from the normal intestinal microbiota are scarce. In this study, 1024 Gram-positive and Gram-negative anaerobic isolates from the normal intestinal microbiota were analyzed for in-vitro susceptibility against solithromycin and compared to azithromycin, amoxicillin/clavulanic acid, ceftriaxone, metronidazole and levofloxacin by determining the minimum inhibitory concentration (MIC). Solithromycin was active against Bifidobacteria (MIC50, 0.008 mg/L) and Lactobacilli (MIC50, 0.008 mg/L). The MIC50 for Clostridia, Bacteroides, Prevotella and Veillonella were 0.5, 0.5, 0.125 and 0.016 mg/L, respectively. Gram-positive anaerobes were more susceptible to solithromycin as compared to the other antimicrobials tested. The activity of solithromycin against Gram-negative anaerobes was equal or higher as compared to other tested agents.

Novel tricyclics (e.g., GSK945237) as potent inhibitors of bacterial type IIA topoisomerases.

During the course of our research on the lead optimisation of the NBTI (Novel Bacterial Type II Topoisomerase Inhibitors) class of antibacterials, we discovered a series of tricyclic compounds that showed good Gram-positive and Gram-negative potency. Herein we will discuss the various subunits that were investigated in this series and report advanced studies on compound 1 (GSK945237) which demonstrates good PK and in vivo efficacy properties.

Centipeda periodontii in human periodontitis.

This study assessed the subgingival occurrence of the flagellated, Gram-negative, anaerobic rod Centipeda periodontii in chronic periodontitis and periodontal health/gingivitis with species-specific nucleic acid probes, and evaluated the in vitro resistance of subgingival isolates to therapeutic levels of amoxicillin, metronidazole, and doxycycline. Subgingival plaque biofilm specimens from 307 adults with chronic periodontitis, and 48 adults with periodontal health/localized gingivitis, were evaluated with digoxigenin-labeled, whole-chromosomal, DNA probes to C. periodontii ATCC 35019 possessing a 10(4) cell detection threshold. Fifty-two C. periodontii subgingival culture isolates were assessed on antibiotic-supplemented enriched Brucella blood agar for in vitro resistance to either amoxicillin at 2 µg/ml, metronidazole at 4 µg/ml, or doxycycline at 2 µg/ml. A significantly greater subgingival occurrence of C. periodontii was found in chronic periodontitis subjects as compared to individuals with periodontal health/gingivitis (13.4 vs. 0 %, P < 0.003), although high subgingival counts of the organism (≥ 10(6) cells) were rarely detected (1.3 % of chronic periodontitis subjects). In vitro resistance was not found to amoxicillin or metronidazole, and to doxycycline in only 2 (3.9 %) of the 52 C. periodontii clinical isolates studied. These findings indicate that C. periodontii is not a major constituent of the subgingival microbiome in chronic periodontitis or periodontal health/gingivitis. The potential contribution of C. periodontii to periodontal breakdown in the few chronic periodontitis subjects who yielded high subgingival levels of the organism remains to be delineated. C. periodontii clinical isolates were susceptible in vitro to therapeutic concentrations of three antibiotics frequently used in treatment of human periodontitis.

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

Many ß-lactamases have been described in various Gram-negative bacilli (Capnocytophaga, Prevotella, Fusobacterium, etc.) of the oral cavity, belonging to class A of the Ambler classification (CepA, CblA, CfxA, CSP-1 and TEM), class B (CfiA) or class D in Fusobacterium nucleatum (FUS-1). The minimum inhibitory concentrations of ß-lactams are variable and this variation is often related to the presence of plasmids or other mobile genetic elements (MGEs) that modulate the expression of resistance genes. DNA persistence and bacterial promiscuity in oral biofilms also contribute to genetic transformation and conjugation in this particular microcosm. Overexpression of efflux pumps is facilitated because the encoding genes are located on MGEs, in some multidrug-resistant clinical isolates, similar to conjugative transposons harbouring genes encoding ß-lactamases. All these facts lead us to consider the oral cavity as an important reservoir of ß-lactam resistance genes and a privileged place for genetic exchange, especially in commensal strictly anaerobic Gram-negative bacilli.

Antimicrobial photodynamic therapy as an adjunct to non-surgical treatment of aggressive periodontitis: a split-mouth randomized controlled trial.

BACKGROUND: The management of aggressive periodontitis (AgP) represents a challenge for clinicians because there are no standardized protocols for an efficient control of the disease. This randomized controlled clinical trial evaluated the effects of repeated applications of antimicrobial photodynamic therapy (aPDT) adjunctive to scaling and root planing (SRP) in patients with AgP. METHODS: Using a split-mouth design, 20 patients with generalized AgP were treated with aPDT + SRP (test group) or SRP only (control group). aPDT was applied at four periods. All patients were monitored for 90 days. Clinical, microbiologic, and immunologic parameters were statistically analyzed. RESULTS: In deep periodontal pocket analysis (probing depth [PD] ≥ 7 mm at baseline), the test group presented a decrease in PD and a clinical attachment gain significantly higher than the control group at 90 days (P < 0.05). The test group also demonstrated significantly less periodontal pathogens of red and orange complexes and a lower interleukin-1ß/interleukin-10 ratio than the control group (P < 0.05). CONCLUSION: The application of four sessions of aPDT, adjunctive to SRP, promotes additional clinical, microbiologic, and immunologic benefits in the treatment of deep periodontal pockets in single-rooted teeth in patients with AgP.

Comparative evaluation of antimicrobial efficacy of various root canal filling materials along with aloevera used in primary teeth: a microbiological study.

AIM: this study was conducted to evaluate the antimicrobial effectiveness of 6 root canal filling materials and a negative control agent against 18 strains of bacteria isolated from infected root canals of primary molar teeth using agar diffusion assay. MATERIALS: Aloevera with sterile water Zinc oxide and Eugenol, Zinc oxide-Eugenol with aloevera, Calcium hydroxide and sterile water, Calcium hydroxide with sterile water and aloevera, Calcium hydroxide and Iodoform (Metapex) and Vaseline (Control). MIC and MBC of aloevera was calculated. RESULTS: All materials except Vaseline showed varied antimicrobial activity against the test bacterias. The zones of inhibition were ranked into 4 inhibition categories based on the proportional distribution of the data. All the 18 bacterial isolates were classified under 2 groups based on Gram positive and Gram negative aerobes. Statistical analysis was carried out to compare the antimicrobial effectiveness between materials tested with each of the bacterial groupings. CONCLUSION: Aloevera + Sterile Water was found to have superior antimicrobial activity against most of the microorganisms followed by ZOE + Aloevera, calcium hydroxide + Aloevera, ZOE, calcium hydroxide, Metapex in the descending order and Vaseline showed no inhibition.

Antimicrobial efficacy of denture adhesives on some oral malodor-related microbes.

The objective of the study was to determine the antimicrobial efficacy of three denture adhesives toward Streptococcus oralis, mutans, Prevotella oralis and Fusobacterium nucleatum. Adhesives used were Corega Ultra(®), Fixodent Pro Original(®) and Biotene(®) Denture Grip. For Streptococcus oralis and Streptococcus mutans, four tubes of Trypticase Soy Broth 10 mL and 1 g denture of adhesive were used. In addition four tubes of Trypticase Soy Broth 10 mL without any denture adhesive was employed as control. For Prevotella oralis and Fusobacterium nucleatum, four tubes of thioglycolate 10 mL and 1 g denture adhesive were used for each one, while four tubes of thioglycolate 10 mL without adhesive served as control. All samples were incubated for 48 h at 37°C. After 48 h, the number of colonies was counted and the mean was extracted as cfu/mL. The results were evaluated with ANOVA on ranked data and Tukey's post hoc test at α = 0.05. Streptococcus oralis, mutans, Prevotella oralis and Fusobacterium nucleatum showed decreased number of colonies for each denture adhesive compared to the control. Under the conditions of this in vitro study, all the tested denture adhesives showed antimicrobial efficacy. However, in contrast to the hypothesis, there were differences among them. Corega Ultra(®) and Biotene(®) Denture Grip were more effective for all the tested oral malodor-related microbes than Fixodent Pro Original(®).

Chicken egg yolk antibody (IgY) controls Solobacterium moorei under in vitro and in vivo conditions.

Solobacterium moorei is a causative agent in diseases such as oral halitosis, bacteremia, and necrobacillosis-associated thrombophlebitis. The objective of this study was to determine the effectiveness of chicken egg yolk antibody (IgY) in controlling S. moorei. Intact S. moorei cells were used as an immunogen to immunize four White Leghorn laying hens. IgY, extracted from egg yolks obtained from these immunized hens, was purified using water dilution, two-step salt precipitation, and ultrafiltration. The purity of the IgY obtained was approximately 87.3 %. The antibody titer of the IgY was determined by enzyme-linked immunosorbent assay. The antibody titer peaked at 10,000 following the third immunization. In order to evaluate the inhibitory effects of the specific IgY, the growth of S. moorei in liquid media was measured every 12 h using a microplate reader at 600 nm. Biofilm formation of S. moorei was quantified by staining with crystal violet. The specific binding ability of IgY was further confirmed by the use of immunofluorescence and immunoelectron microscopy. Growth and biofilm formation of S. moorei were significantly (P<0.05) inhibited by 20 and 40 mg/ml specific IgY compared with the control. The specific IgY also decreased the bacterial level in the oral cavity of mice after infection with S. moorei. This study demonstrates that the growth and biofilm formation of S. moorei can be effectively inhibited by specific IgY. As a result, IgY technology may have application in the control of diseases caused by S. moorei.

Anti-anaerobic activity of a new ß-lactamase inhibitor NXL104 in combination with ß-lactams and metronidazole.

NXL104 is a new ß-lactamase inhibitor (BLI) that inhibits class A and class C ß-lactamase enzymes. In this study, the activity of NXL104 in combination with the third-generation cephalosporins ceftazidime (CAZ) and ceftriaxone (CRO) or with piperacillin (PIP) was evaluated against 316 anaerobic bacteria. Minimum inhibitory concentrations (MICs) were determined using an agar dilution method. The BLIs NXL104 or tazobactam (TAZ) were added to the ß-lactams at a fixed concentration of 4 mg/L. A triple combination of NXL104 with an 8:1 ratio of CAZ and metronidazole (MTZ) was also tested. The activities of CAZ, CRO and PIP in combination with NXL104 were enhanced against many of the bacteria. MIC(50) values (MIC for 50% of the organisms) for CAZ+NXL104 were 8-16-fold lower than those of CAZ against Gram-negative anaerobes. Antibiotic resistance rates against all anaerobic strains were: CAZ, 37.7%; CRO, 31%; CAZ+NXL104, 15.2%; CRO+NXL104, 5.4%; and MTZ, 4.1%. No resistant strains could be observed with PIP+TAZ, PIP+NXL104 or the triple combination MTZ+CAZ+NXL104. In conclusion, the triple combination of MTZ+CAZ+NXL104 demonstrated potent antibacterial activity against anaerobes representing most clinical species. It appears appropriate for the treatment of polymicrobial infections, since CAZ+NXL104 also exhibits potent activity against ß-lactamase-producing Enterobacteriaceae and Pseudomonas aeruginosa. It is currently being tested in phase 2 clinical trials for the treatment of complicated intra-abdominal infections.

Antimicrobial resistance determinants among anaerobic bacteria isolated from footrot.

Antibiotic resistance has been evaluated among 36 Gram negative and anaerobic bacilli (10 Bacteroides, 11 Prevotella, 7 Porphyromonas and 8 Fusobacterium strains) isolated from clinical cases of caprine and ovine footrot (necrotic pododermatitis). The initial analysis on this bacterial consortium evaluates the relationships existing among antimicrobial resistance determinants, phenotype expression and mobilization potential. The Bacteroides strains were generally resistant to penicillins, first-generation cephalosporins, tetracycline and erythromycin, and expressed low level of ß-lactamase activity. The main determinants found among the Bacteroides strains were cepA and tetQ genes, conferring resistance to ß-lactams and tetracycline, respectively. A general susceptibility to ß-lactams was shown for most Prevotella, Porphyromonas and Fusobacterium strains, where none of the ß-lactamase genes described in Bacteroides was detected. Resistance to tetracycline and/or erythromycin was found among the three bacterial groups. Although tetQ genes were detected for several Prevotella and Porphyromonas strains, a unique ermF positive was revealed among Prevotella strains. The expression of resistance markers was not related with the polymorphism of their coding sequences. However, the finding of sequence signatures for conjugative transposons in the vicinities of tetQ and ermF suggests a mobilization potential that might have contributed to the spread of antimicrobial resistance genes.

Antimicrobial susceptibility of Gram-negative organisms from intraabdominal infections and evolution of isolates with extended spectrum ß-lactamases in the SMART study in Spain (2002-2010).

INTRODUCTION: The SMART (Study for Monitoring Antimicrobial Resistance Trends) surveillance study records the antimicrobial susceptibility of Gram-negative bacilli obtain from intraabdominal infections with special focus in isolates with extended spectrum ß-lactamases (ESBLs). MATERIAL AND METHODS: The antimicrobial susceptibility of 8,869 isolates was analyzed by microdilution during the SMART study performed in Spain from 2002 to 2010. Isolates were recovered in 16 centres. RESULTS: Escherichia coli was the most prevalent pathogen (60.9% from intraabdominal infections acquired in the community and 49.9% in those from nosocomial origin) followed by Klebsiella pneumoniae (8.9% vs 9.2%). Pseudomonas aeruginosa was more common in intraabdominal infections from nosocomial origin (5.6% community and 8.6% nosocomial). Frequency of ESBL-producing isolates was: E. coli, 8.7%; K. pneumoniae, 8.4%; Klebsiella oxytoca, 1.4%; and Proteus mirabilis, 1.6%. Overall, ESBL-producing isolates were more frequently isolated from elderly patients (6.8% >60 years). Ertapenem and meropenem were the most active antimicrobials (susceptibility range with EUCAST criteria, 89.0-100%) when considering all Enterobacteriaceae isolates and also against ESBL producers (95.5-100%). Susceptibility of amoxicillin/clavulanic acid and piperacillin/tazobactam was lower, particularly among ESBL-producing isolates. Nevertheless, ertapenem maintained a good activity (susceptibility >95%) in ESBL-producers that were resistant to amoxicillin/clavulanic acid, piperacillin/tazobactam or fluoroquinolones. CONCLUSIONS: Antimicrobial susceptibility data from the SMART-Spain study reinforce current therapeutic guidelines of intraabdominal infections that include ertapenem as the empirical choice for treatment. This is also supported by the high frequency of ESBL-producers in our geographic area.

[Participation of gram-negative anaerobes in infections in hospitalized patients]. / Udzial beztlenowych Gram-ujemnych bakterii w zakazeniach hospitalizowanych pacjentów.

The aim of the study was to assess the prevalence and antibiotic susceptibility profiles of strictly anaerobic Gram-negative bacteria isolated from clinical samples taken from hospitalized patients from 01.01.2007 to 31.12.2008. The specimens were cultured using media, incubated at 37 degrees C under anaerobic conditions. Biochemical identification and antibiotic susceptibility were done in an automated system ATB Expression (bioMerieux S.A, France). For selected strains of Bacteroides sp. sensitivity was determined using E-test (AB BIODISK, Sweden). Overall 1274 strains of obligate anaerobes were isolated. Gram-negative bacteria were cultured in number of 333 strains. Most frequently isolated was Bacteroides sp. (46,9%) and Prevotella sp. (29,7%). Isolated bacteria are still susceptible to imipenem (100%), metronidazole (100%) and beta-lactam antibiotics with beta-lactamase inhibitors: amoxicillin/clavulanate (97,8%) piperacillin/tazobactam (99,1%), ticarcillin/clavulanate (99,1%).