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Assam tea or Miang is a local name of Camellia sinensis var. assamica in northern Thailand. By the local wisdom, Assam tea leaves are used as the raw material in tea fermentation to produce "Fermented Miang" consumed by people in northern Thailand and the countries nearby. In this study, twenty-eight bacterial isolates were obtained from Assam tea leaf samples collected from Nan province, Thailand. Bacterial isolates were identified within 6 genera including Bacillus, Floricoccus, Kocuria, Lysinibacillus, Micrococcus and Staphylococcus. Among these, the strain ML061-4 shared 100.0 and 99.4% similarity of 16S rRNA and rpoB gene sequence with F. penangensis JCM 31735 T , respectively. This is the first discovery of F. penangensis in Thailand. F. penangensis ML061-4 exhibited probiotic characteristics including lactic acid production (9.19 ± 0.10 mg/ml), antibacterial activities (Escherichia coli ATCC 25922 and E. coli O157:H7 DMST 12743), acid and bile salt tolerance (71.1 and 54.9%, respectively), autoaggregation (97.0%), coaggregation (66.0% with E. coli O157:H7), cell surface hydrophobicity (90.0%), bacterial adhesion (82.9% with Lactobacillus plantarum FM03-1), competitive inhibition (17.8% with E. coli O157:H7) and competitive exclusion (34.9% with E. coli O157:H7). Overall, the data suggested that F. penangensis ML061-4 had a great potential to be a probiotic.

Background: To our knowledge, there is a lack of evidence on the effect of Antimicrobial Photodynamic Therapy (aPDT) by the application of curcumin against complex biofilms of dental caries lesions. This study aimed to evaluate the viability, vitality, and acid metabolism of infected dentin caries microcosms treated with curcumin-mediated aPDT., Methods: After microcosm biofilms growing anaerobically on bovine dentin disks immersed in McBain medium with 1% sucrose at 37 °C for 5 days, the biofilms were treated by the association of DMSO water solution or 600 μmol L -1 curcumin with 0, 37.5 or 75 J cm -2 blue LED (455 nm). Then, the colony-forming units (CFU) counts of total microorganisms, total streptococci, mutans streptococci, and total lactobacilli were determined by plating. The lactic acid concentration was analyzed by enzymatic spectrophotometry method, while the vitality of intact biofilms was evaluated by confocal laser scanning microscope (CLSM). Statistical analysis was performed by Kruskal Wallis and post-hoc Dunn's tests (P < 0.05)., Results: Curcumin alone did not affect the viability of microorganisms and the vitality of intact biofilms. However, 75 J cm -2 LED alone decreased the total microorganisms and total lactobacilli counts. The combination of curcumin and LED reduced significantly the counts of all microorganism groups and the vitality of intact biofilms. Differences were not observed between the lactic acid concentrations of distinct groups., Conclusions: Therefore, curcumin-mediated aPDT was effective in reducing the viability and the vitality of infected dentin caries microcosms, without interfering in their acidogenicity., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Background: Gut dysbiosis associated with the use of proton-pump inhibitors (PPIs) has been found to lead to the occurrence of infectious and inflammatory adverse events. A longitudinal observational cohort study has demonstrated the heightened risk of death associated with PPI use., Summary: We evaluated meta-analyses to determine the association between PPI use and infectious and inflammatory diseases. Meta-analyses showed that PPI use is a potential risk for the development of enteric infections caused by Clostridium difficile, as well as small intestinal bacterial overgrowth, spontaneous bacterial peritonitis, community-acquired pneumonia, hepatic encephalopathy, and adverse outcomes in inflammatory bowel disease. We also examined changes in the composition and function of the gut microbiota with the use of PPIs. PPI use significantly increased the presence of Streptococcaceae and Enterococcaceae, which are risk factors for C. difficile infection, and decreased that of Faecalibacterium, a commensal anti-inflammatory microorganism. Key Message: High-throughput, microbial 16S rRNA gene sequencing has allowed us to investigate the association between the gut microbiome and PPI use. Future prospective comparison studies are necessary to confirm this association, and to develop new strategies to prevent complications of PPI use., (© 2017 Japanese Gastroenterological Association Published by S. Karger AG, Basel.)

The aims of this study were to determine the in vitro activity profile of ceftobiprole, a pyrrolidinone cephalosporin, against a large number of bacterial pathogens and to propose zone diameter breakpoints for clinical categorisation according to the European Committee on Antimicrobial Susceptibility Testing (EUCAST) minimum inhibitory concentration (MIC) breakpoints. MICs of ceftobiprole were determined by broth microdilution against 1548 clinical isolates collected in eight French hospitals. Disk diffusion testing was performed using 30 μg disks according to the method of the Comité de l'Antibiogramme de la Société Française de Microbiologie (CA-SFM). The in vitro activity of ceftobiprole, expressed by MIC(50/90) (MICs for 50% and 90% of the organisms, respectively) (mg/L), was as follows: meticillin-susceptible Staphylococcus aureus, 0.25/0.5; meticillin-resistant S. aureus (MRSA), 1/2; meticillin-susceptible coagulase-negative staphylococci (CoNS), 0.12/0.5; meticillin-resistant CoNS, 1/2; penicillin-susceptible Streptococcus pneumoniae, ≤ 0.008/0.03; penicillin-resistant S. pneumoniae, 0.12/0.5; viridans group streptococci, 0.03/0.12; β-haemolytic streptococci, ≤ 0.008/0.016; Enterococcus faecalis, 0.25/1; Enterococcus faecium, 64/128; Enterobacteriaceae, 0.06/32; Pseudomonas aeruginosa, 4/16; Acinetobacter baumannii, 0.5/64; Haemophilus influenzae, 0.03/0.12; and Moraxella catarrhalis, 0.25/0.5. According to the regression curve, zone diameter breakpoints could be 28, 26, 24 and 22 mm for MICs of 0.5, 1, 2 and 4 mg/L respectively. In conclusion, this study confirms the potent in vitro activity of ceftobiprole against many Gram-positive bacteria, including MRSA but not E. faecium, whilst maintaining a Gram-negative spectrum similar to the advanced-generation cephalosporins such as cefepime. Thus ceftobiprole appears to be well suited for the empirical treatment of a variety of healthcare-associated infections., (Copyright © 2011 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.)

Hospital-acquired infections and antibiotic-resistant bacteria continue to be major health concerns worldwide. Particularly problematic is methicillin-resistant Staphylococcus aureus (MRSA) and its ability to cause severe soft tissue, bone or implant infections. First used by the Australian Aborigines, Tea tree oil and Eucalyptus oil (and several other essential oils) have each demonstrated promising efficacy against several bacteria and have been used clinically against multi-resistant strains. Several common and hospital-acquired bacterial and yeast isolates (6 Staphylococcus strains including MRSA, 4 Streptococcus strains and 3 Candida strains including Candida krusei) were tested for their susceptibility for Eucalyptus, Tea tree, Thyme white, Lavender, Lemon, Lemongrass, Cinnamon, Grapefruit, Clove Bud, Sandalwood, Peppermint, Kunzea and Sage oil with the agar diffusion test. Olive oil, Paraffin oil, Ethanol (70%), Povidone iodine, Chlorhexidine and hydrogen peroxide (H(2)O(2)) served as controls. Large prevailing effective zones of inhibition were observed for Thyme white, Lemon, Lemongrass and Cinnamon oil. The other oils also showed considerable efficacy. Remarkably, almost all tested oils demonstrated efficacy against hospital-acquired isolates and reference strains, whereas Olive and Paraffin oil from the control group produced no inhibition. As proven in vitro, essential oils represent a cheap and effective antiseptic topical treatment option even for antibiotic-resistant strains as MRSA and antimycotic-resistant Candida species.

Objective: To determine the proportion of subjects with oropharyngeal streptococci resistant to either levofloxacin or azithromycin prior to and during antibacterial exposure, and to follow temporal changes in the proportion of resistant and susceptible isolates through 6 weeks post-exposure. This randomized, open-label, single-center study is registered with ClinicalTrials.gov (identifier: NCT00821782)., Research Design and Methods: A total of 143 healthy volunteers (levofloxacin, n = 71; azithromycin, n = 72) without antibacterial exposure in the previous 90 days received either levofloxacin 750 mg once daily for 5 days or azithromycin 500 mg once daily on day 1 and 250 mg once daily on days 2 through 5. Oropharyngeal cultures were obtained pre-exposure, at day 5, and at 2, 4, and 6 weeks post-dosing. Bacterial strains were identified and the minimum inhibitory concentrations for levofloxacin and azithromycin were determined., Results: At study entry 117 streptococci were isolated from 72 subjects randomized to azithromycin and 53 (45.3%) were azithromycin-resistant. None of the 121 streptococci isolated from 71 subjects randomized to.levofloxacin were colonized by a levofloxacin-resistant microorganism prior to dosing. At the end of dosing, the number of subjects with resistant streptococci (S. mitis, S. salivarius, S. sanguis, or alpha streptococcus species [spp.]) increased in azithromycin-exposed subjects and resistant isolates remained through 6 weeks post-dosing. In contrast, a small number of levofloxacin-resistant streptococci were observed at the end of dosing but decreased by week 2 post-dosing and continued to decrease through the 6-week evaluation period (p < 0.001 azithromycin vs. levofloxacin for S. mitis, S. salivarius, S. sanguis and alpha streptococcus spp. at week 6). Limitations of this study included the fact that, since previous antibiotic use was self-reported, genetic typing was not done. The results of this study may not be completely generalizable, because subjects in this study received study drug under directly-observed conditions, thus ensuring compliance., Conclusions: Both antibacterial agents were well tolerated. Levofloxacin 750 mg administered for 5 days was associated with less microbial resistance than that observed with azithromycin in healthy subjects.

Objectives: Toothbrushes are rapidly contaminated with different microorganisms, which colonize the oral cavity and interdental spaces. This can represent a possible cause of infection or reinfection. In this study, the ozone experimental effect upon toothbrushes microflora was estimated microbiologically before and after saturation with ozone gas., Methods: Fifty used toothbrushes coming from children and adults were entered our study. Microorganisms were enumerated and identified. Bristles from each brush were soaked in ozone saturated PBS solution for 5, 10, 15, 20 and 30 min and the total microbial population was reassessed., Results: Counts of microorganisms isolated per brush varied between 10(2) and 10(7) CFU. Candida albicans was present in used toothbrushes. No obligate anaerobes were isolated. Members of Streptococcaceae family were regularly found (65.2%) belonging to the following species: Streptococcus pyogenes, S. mutans, S. mitis, S. oralis, S. sobrinus, S. viridans, S. salivarius, S. sanguis, Aerococcus viridans. A. viridans and S. mutans were more frequently isolated on children toothbrushes while Staphylococcus aureus and S. epidermidis were found on adults brushes. Escherichia coli, Pseudomonas sp. and Enterococcus sp., were also recovered. We found that the ozone treatment decreased gradually the microbial load. However, a bacterial re-growth was effective following short ozonation period. Decontamination was complete after an extended exposure to ozone for 30 min., Conclusions: Ozone application was found to remove the toothbrushes bristles microbiota following conventional brushing. Maximum decontamination efficacy of ozone treatment was observed after 30 min while exposure for short time periods seems to be inefficient which probably reflect the low dose of ozone used in this study.

Two antimicrobial peptides from haemocytes of the American lobster, Homarus americanus H. Milne Edwards 1837, were isolated and partially characterised - the first such description for this species. CAP-2, an approximately 12kDa peptide, contained amino acid sequences corresponding to the predicted sequence for Hoa-crustin. Crustins are whey acidic protein (WAP) domain - containing peptides isolated from crustacean haemocytes. CAP-2 did not have any activity towards the Gram positive coccus Aerococcus viridans unlike carcinin, a crustin from Carcinus maenas haemocytes, which may partially explain the lobster's susceptibility to this bacterium. A second peptide, CAP-1, was a multimer composed of 4-6kDa subunits with similarities to amphibian temporins. CAP-1 may represent a novel group of antimicrobial peptides for marine invertebrates and has been tentatively named 'homarin'. Homarin had bacteriostatic activity against some Gram negative bacteria and both protozoastatic and protozoacidal activity against two cultured scuticociliate parasites Mesanophrys chesapeakensis and Anophryoides haemophila, the latter a significant pathogen of H. americanus.

In-vitro MICs and minimum bactericidal concentrations (MBCs) of daptomycin, linezolid, tigecycline, vancomycin and teicoplanin against Gram-positive bacteria were determined using the broth microdilution method for ten blood isolates each of methicillin-susceptible Staphylococcus aureus (MSSA), methicillin-resistant S. aureus (MRSA), including two vancomycin-intermediate S. aureus (VISA), vancomycin-resistant Enterococcus faecium and Enterococcus faecalis. One strain of VISA was tested in a time-kill synergism assay of daptomycin combined with oxacillin, imipenem, rifampicin and isepamicin. Daptomycin showed excellent in-vitro bactericidal activity against all the isolates tested, with no tolerance or synergism effects when combined with other agents, except with rifampicin against VISA. Vancomycin had better bactericidal activity against MRSA and MSSA than did teicoplanin. Linezolid had the poorest bactericidal activity against the isolates tested, with 100% tolerance by the MSSA and VRE isolates, and 80% tolerance by the MRSA isolates. Tolerance towards tigecycline was exhibited by 40% of the MRSA isolates, 100% of the MSSA and vancomycin-resistant E. faecalis isolates, and 90% of the vancomycin-resistant E. faecium isolates.

We present here the biochemical and genetic characterization and antimicrobial susceptibility of 58 isolates of Aerococcus viridans isolated in pure culture from different clinical specimens of normally sterile body sites of pigs. A. viridans isolates were commonly susceptible to beta-lactam antimicrobials and exhibited a great genetic heterogeneity as determined by pulsed-field gel electrophoresis typing. The results indicate that A. viridans might be included in the list of possible etiological agents causing disease in pigs.

Aims: To investigate the effects of two prebiotics and trehalose on the production of bacteriocins., Methods and Results: Four carbohydrates [dextrose, fructo-oligosaccharides (FOS), raffinose, and trehalose] were used as the sole carbon source in a simple broth. Five bacteriocin-producing strains of bacteria, including those producing nisin, enteriocin, and other bacteriocins, were used, and their inhibitory activities when grown on each carbohydrate were determined. The inhibitory activity assay was performed using the agar well diffusion method, and Lactobacillus sakei JCM 1,157(T) was used as the indicator strain. Effective enhancement of bacteriocin production was observed with FOS and trehalose incubation., Conclusions: The results suggest that FOS and trehalose can effectively enhance the production of the five kinds of bacteriocins evaluated in this study., Significance and Impact of the Study: This study offers useful information for not only a new application of FOS and trehalose, but also the potential improvement of food preservation.

The antibiotic resistances of 45 lactic acid bacteria strains belonging to the genera Lactobacillus, Streptococcus, Lactococcus, Pediococcus, and Leuconostoc were investigated. The objective was to determine antibiotic resistances and to verify these at the genetic level, as is currently suggested by the European "qualified presumption of safety" safety evaluation system for industrial starter strains. In addition, we sought to pinpoint possible problems in resistance determinations. Primers were used to PCR amplify genes involved in beta-lactam antibiotic, chloramphenicol, tetracycline, and erythromycin resistance. The presence of ribosomal protection protein genes and the ermB gene was also determined by using a gene probe. Generally, the incidences of erythromycin, chloramphenicol, tetracycline, or beta-lactam resistances in this study were low (<7%). In contrast, aminoglycoside (gentamicin and streptomycin) and ciprofloxacin resistances were higher than 70%, indicating that these may constitute intrinsic resistances. The genetic basis for ciprofloxacin resistance could not be verified, since no mutations typical of quinolone resistances were detected in the quinolone determining regions of the parC and gyrA genes. Some starter strains showed low-level ampicillin, penicillin, chloramphenicol, and tetracycline resistances, but no known resistance genes could be detected. Although some strains possessed the cat gene, none of these were phenotypically resistant to chloramphenicol. Using reverse transcription-PCR, these cat genes were shown to be silent under both inducing and noninducing conditions. Only Lactobacillus salivarius BFE 7441 possessed an ermB gene, which was encoded on the chromosome and which could not be transferred in filter-mating experiments. This study clearly demonstrates problems encountered with resistance testing, in that the breakpoint values are often inadequately identified, resistance genes may be present but silent, and the genetic basis and associated resistance mechanisms toward some antibiotics are still unknown.

Phagocytic responses in circulating hemocytes of the lobster Homarus americanus were measured before and after treatment of lobsters with 2 different immunogens: (1) lipolysaccharide (LPS) or endotoxin from a non-pathogenic Pseudomonas perolens, and (2) a vancomycin/live Gram-positive pathogen (Aerococcus viridans [var.] homari) combination, essentially attenuated cells, shown previously to induce a high degree of resistance to this pathogen. The responses elicited by each of the immunogens were markedly different. Hemocytes drawn from LPS-treated lobsters showed significant, largely non-specific, increases in phagocytic responses over baseline values against sheep red blood cells and an array of test bacteria, with the notable exception of the pathogen. In marked contrast, induction with the vancomycin/live pathogen combination resulted in highly significant and specific increases in phagocytic responses to the pathogen and to the related, (but avirulent) strains of the pathogen, as well as inducing in the lobsters the usual high degree of resistance to the pathogen. These results suggest that quantitative and qualitative variations in phagocytic and resistance levels induced in at least 1 crustacean genus are determined largely by the particular characteristics of the immunogen.

Gelatin microparticles containing propolis ethanolic extractive solution were prepared by spray-drying technique. Particles with regular morphology, mean diameter ranging of 2.27 microm to 2.48 microm, and good entrapment efficiency for propolis were obtained. The in vitro antimicrobial activity of microparticles was evaluated against microorganisms of oral importance (Enterococcus faecalis, Streptococcus salivarius, Streptococcus sanguinis, Streptococcus mitis, Streptococcus mutans, Streptococcus sobrinus, Candida albicans, and Lactobacillus casei). The utilized techniques were diffusion in agar and determination of minimum inhibitory concentration. The choice of the method to evaluate the antimicrobial activity of microparticles showed be very important. The microparticles displayed activity against all tested strains of similar way to the propolis, showing greater activity against the strains of E. salivarius, S. sanguinis, S. mitis, and C. albicans.

Environmental bacteria have emerged over the past few years to become significant causes of mastitis. Bacteria in this group are often reported by practicing veterinarians to be increasingly resistant to intramammary therapy and responsible for elevated bulk tank somatic cell counts. The purpose of this study was to determine the extent of association of the minimum inhibitory concentrations for selected antimicrobial agents with environmental bacteria isolated from bulk tank milk on California dairies and their housing facilities, husbandry practices, and antimicrobic-use strategies. Bulk tank milk samples were collected from 2 dairy cooperatives that had their milk cultured at the Milk Quality Laboratory, University of California Davis, Veterinary Medicine Teaching and Research Center in Tulare, CA. Samples were collected from July 2001 through March 2002 on 88 d; and 404 environmental bacteria isolated from 93 dairies were found. Minimum inhibitory concentrations were determined on 337 of the isolates for 10 antimicrobial agents. Cluster analysis was performed on the minimum inhibitory concentration values for each organism, and 4 antimicrobial clusters with varying degrees of resistance were found.A 69-question survey questionnaire was completed on-farm for 49 of the 73 dairies that had at least 3 environmental bacterial isolates. The questionnaire sought information on housing facilities, milking management, mastitis prevention, antimicrobial usage strategies, and owner/veterinary involvement in disease control and prevention. Multinomial logistic regression analysis found significant associations between the antimicrobial agent-resistance cluster groups and some of the housing and bedding practices, failure to dry udders before milking, and antimicrobial treatment of nonmastitis conditions. No association was noted for antimicrobial agent treatment of mastitis and the resistance cluster patterns.

In the production of the Spanish traditional blue-veined Cabrales cheese, lactic acid bacteria strains free of antibiotic resistance that have a transferrable capacity are necessary as components of a specific starter. To select for these bacteria, the minimum inhibitory concentration (MIC) of 12 antibiotics and 2 mixtures (containing beta-lactamase inhibitor and penicillin) were determined by microbroth and agar dilution techniques in 146 strains belonging to the genera Lactococcus, Enterococcus, Lactobacillus, and Leuconostoc. The antibiotic-resistance profiles of Lactococcus and Enterococcus species were different from those of Lactobacillus and Leuconostoc, but clear genus- or species-associated patterns were not observed. Cefoxitin and metronidazole were not effective against bacteria of these genera. The MICs of beta-lactam antibiotics for lactobacilli and leuconostoc isolates were higher than those for lactococci and enterococci, but no strain was clinically resistant. All lactobacilli and leuconostoc isolates were resistant to high levels of vancomycin, a type of resistance not seen among the tested members of the genera Lactococcus and Enterococcus. The majority of the observed resistance appeared to be either intrinsic or nonspecific, although some strains of Lactococcus lactis, Enterococcus spp., and Lactobacillus spp. were resistant to antibiotics, such as chloramphenicol, erythromycin, clindamycin, or tetracycline.

Aims: To determine the effect of diet acidification and an in-feed antibiotic growth promotant (Tylosin, Ty) on selected culturable bacterial populations in the gastrointestinal tract (GIT) of mice., Methods and Results: Female C57Bl mice were given a standard diet supplemented with Acid Pak (AP) or Ty in the drinking water. After 21 days, lumen and adherent populations of Enterobacteriaceae, enterococci/streptococci, and lactic acid bacteria (LAB) from the ileum, caecum, colon and faeces were enumerated. General intestinal health was assessed by the frequency of haemolytic bacteria in the different intestinal compartments. Contrary to expectations, AP and Ty significantly increased haemolytic bacteria in the lumen of the caecum and colon (P<0.05). The small but significant growth-enhancing effect of Ty (P<0.05) was associated with decreases in enterococci/streptococci and surprisingly, LAB, as well as increases in coliforms. AP, which failed to improve growth rates, reduced coliforms, had limited effects on enterococci/streptococci, and specifically failed to promote the growth of LAB populations in all intestinal compartments. Ty supplementation was also associated with a significant increase in macrolide-resistant enterococci throughout the GIT., Conclusions: Dietary acidification is less effective than Ty in modulating the population dynamics of selected culturable populations of enteric bacteria., Significance and Impact of the Study: The mouse can provide a useful experimental model to examine the effects of new dietary supplements, formulations or regimes on changes in microbial population dynamics, including monitoring for antibiotic resistance.

Abiotrophia and Granulicatella species have been associated with various infections. Antimicrobial susceptibility data for these nutritionally variant streptococcus-like organisms, especially for pediatric isolates, are very limited. Little is known about the genetic bases of their resistance mechanisms. We report the results of identification to bacterial species level, antimicrobial susceptibility testing, macrolide resistance testing, and detection of genes encoding that resistance for a collection of 15 pediatric clinical isolates from normally sterile sites. Our results indicate that the prevalence of beta-lactam and macrolide resistance is high and that both erm and mef are found in these isolates.

Lactic acid bacteria isolated from Boza, a cereal-fermented beverage from Belogratchik, Bulgaria, were screened for the production of bacteriocins. With the first screening, 13 of the 52 isolates inhibited the growth of Listeria innocua and Lactobacillus plantarum. The cell-free supernatant of one of these strains, classified as Leuconostoc mesenteroides subsp. dextranicum ST99, inhibited the growth of Bacillus subtilis, Enterococcus faecalis, several Lactobacillus spp., Lactococcus lactis subsp. cremoris, Listeria innocua, Listeria monocytogenes, Pediococcus pentosaceus, Staphylococcus aureus and Streptococcus thermophilus. Clostridium spp., Carnobacterium spp., L. mesenteroides and Gram-negative bacteria were not inhibited. Maximum antimicrobial activity, i.e. 6,400 arbitrary units (AU)/ml, was recorded in MRS broth after 24 h at 30 degrees C. Incubation in the presence of protease IV and pronase E resulted in loss of antimicrobial activity, confirming that growth inhibition was caused by a bacteriocin, designated here as mesentericin ST99. No loss in activity was recorded after treatment with alpha-amylase, SDS, Tween 20, Tween 80, urea, Triton X-100, N-laurylsarcosin, EDTA and phenylmethylsulfonylfluoride. Mesentericin ST99 remained active after 30 min at 121 degrees C and after 2 h of incubation at pH 2 to 12. Metabolically active cells of L. innocua treated with mesentericin ST99 did not undergo lysis. Mesentericin ST99 did not adhere to the cell surface of strain ST99. Precipitation with ammonium sulfate (70% saturation), followed by Sep-Pack C18 chromatography and reverse-phase HPLC on a C18 Nucleosil column yielded one antimicrobial peptide.

This report describes the effects of heat, sodium lactate, and sodium diacetate on the viabilities of Weissella viridescens ATCC 12706, Aerococcus viridans MPL-1 and MPL-B, and Carnobacterium viridans ATCC BAA 336. The latter three organisms were isolated from commercial product and have previously been shown to produce green discolourations in cooked cured bologna. W. viridescens was heat resistant in beef bologna (D(60 degrees C)=14.7 min) but not in APT broth. A. viridans and C. viridans were much more sensitive to heat (D(60 degrees C) in beef bologna < or =1.3 min), indicating that these organisms were probably post-pasteurization contaminants. Sodium lactate (3.0%) alone or in combination with 0.3% sodium diacetate slowed the growth rate and reduced the final cell numbers of A. viridans and C. viridans in inoculated bologna. W. viridescens was only slightly affected by the combined antimicrobials. The combination of sodium lactate and sodium diacetate prevented A. viridans and C. viridans from affecting the colour of beef bologna. However, lactate and diacetate themselves reduced red colour, as measured by HunterLab colourimetry. HunterLab a values for fresh beef bologna were 13.4 (no antimicrobial added), 9.6 (3.0% sodium lactate), 8.0 (0.3% sodium diacetate), and 7.9 (3.0% sodium lactate + 0.3% sodium diacetate).

This report describes the clinical sources and phenotypic characterization of 16 isolates of Aerococcus sanguinicola. Sixteen conventional tests were used to describe and differentiate the 16 isolates of A. sanguinicola from 30 strains of Aerococcus viridans, 27 strains of Aerococcus urinae, and a single strain each of Aerococcus christensenii and Aerococcus urinaehominis. The phenotypic characterizations of the type strains for each species and 14 A. sanguinicola isolates were also compared in the two reference laboratories. A. sanguinicola are catalase-negative, vancomycin-susceptible, gram-positive cocci arranged in clusters and tetrads, as are all Aerococcus species except A. christensenii (which is arranged in short chains). All 16 isolates of A. sanguinicola were leucine aminopeptidase and pyrrolidonylarylamidase positive, which is unique to this species among the aerococci. All A. sanguinicola isolates grew in broth containing 6.5% NaCl, hydrolyzed hippurate, and were variable in the bile-esculin test. None of the isolates deaminated arginine or were Voges-Proskauer positive. The type strain of A. sanguinicola was isolated from a blood culture of a patient living in Denmark. Seven additional isolates were from patients living in Canada, all with urinary tract infections (six were female). Eight isolates were from patients living in five different states in the United States; five were from patients with urinary tract infections, and three were from blood cultures of one patient each with pneumonia, suspected endocarditis, and unknown clinical conditions. The antimicrobial susceptibility patterns were unremarkable; all isolates tested were susceptible to penicillin, amoxicillin, cefotaxime, cefuroxime, erythromycin, chloramphenicol, vancomycin, quinupristin-dalfopristin (Synercid), rifampin, linezolid, and tetracycline. Six of the 15 cultures were resistant to ciprofloxacin and levofloxacin, but all 15 strains were susceptible to sparfloxacin. High-level resistance was detected for meropenem (2 strains) and trimethoprim-sulfamethonazole (1 strain). Intermediate resistance was detected for trimethoprim-sulfamethoxazole (10 strains) and clindamycin (3 strains).

Seventy-nine isolates of oral streptococci and Aerococcus obtained from blood specimens between December 1997 and January 2000 were tested for high-level gentamicin resistance. Three isolates with minimum inhibitory concentrations (MICs) of > or =1024 microg/ml were selected as potential high-level gentamicin-resistant isolates. The DNA sequence of the structural gene encoding 6'-acetyltransferase-2"-phosphotransferase in the three high-level gentamicin-resistant isolates was investigated according to the method used for Enterococcus faecalis. The results of this gene analysis showed that all the DNA sequence of Aerococcus viridans no. 70, which had the highest MIC (2048 microg/ml), matched that of E. faecalis, whereas no polymerase chain reaction (PCR) products were obtained in the other two isolates that were tested. The mechanism of gentamicin resistance in these two isolates is unknown.

Aerococcus urinae is an uncommon urinary tract pathogen which causes infections predominantly in elderly persons with local and general predisposing conditions. There are few case reports of severe infections caused by Aerococcus urinae among which only 14 cases of endocarditis caused by Aerococcus urinae have been reported. We report the first case of Aerococcus urinae spondylodiscitis. The patient responded to 4 weeks of amoxicillin and clindamycin, and to 5 months of amoxicillin alone.

A new class of acyclic nucleoside phosphonates PMAMG, PMAMA, PMAMC, and PMAMT (compounds 1, 2, 3 and 4) have been synthesized and tested in vitro against a wide variety of viruses, fungi and bacteria. PMAMG (1) was synthesized by the alkylation reaction of acetylguanine with the phosphonate side-chain, diisopropyl [[2-(bromomethyl)aziridin-1-yl]]methylphosphonate (9), followed by deesterification reaction in the presence of TMSBr. In similar way, PMAMA, PMAMC, and PMAMT were prepared.

Aerococcus viridans, a catalase-negative gram-positive coccus rarely causing bacteremia, was isolated from blood cultures of a 52-yr-old man under the granulocytopenic condition. The isolate showed the typical characteristics of A. viridans, i.e., tetrad arrangements in gram stain, positive pyrrolidonyl aminopeptidase (PYR) and negative leucine aminopeptidase (LAP) reactions, and no growth at 45 degrees C. The isolate was revealed to be highly resistant to penicillin, erythromycin, clindamycin, and ceftriaxone, although most strains of A. viridans isolated from the previously reported patients were susceptible to penicillin and other commonly used antibiotics. Even though A. viridans is rarely associated with human infections, it could be a potential causative agent of bacteremia, especially in immunocompromised patients.

Aerococcus urinae is a newcomer in clinical and microbiological practice, causing urinary tract infections, bacteraemia/septicaemia and/or endocarditis. This study presents for the first time an evaluation of the activity of a representative panel of antibiotics against a large number of A. urinae isolates. The in vitro susceptibilities (MICs) of 56 isolates of A. urinae to 14 antibiotics were determined by agar dilution. In general, A. urinae isolates showed little inter-isolate variability, and had low MICs of penicillin, amoxicillin, piperacillin, cefepime, vancomycin and rifampicin. High-level aminoglycoside resistance was not found for any of the isolates. Moderate to good activity was seen with quinolones, erythromycin and tetracycline. Isolates from two patients with endocarditis were studied with time-kill curves for penicillin, gentamicin and vancomycin. Penicillin and vancomycin alone exhibited slow or no bactericidal activity against the two strains. When combining either penicillin or vancomycin with gentamicin, rapid bactericidal activity was obtained for both strains with both combinations. The treatment options for A. urinae seem to include penicillins for less severe cases. In severe cases, i.e. endocarditis, the time-kill investigations suggest a beneficial effect of combination with gentamicin. In the penicillin-allergic patient vancomycin in combination with gentamicin represents the most obvious alternative.

Cross-resistance and multi-resistance to selected antibiotics was determined for Escherichia coli, Klebsiella pneumoniae, Enterobacter cloacae, Pseudomonas aeruginosa, Staphylococcus aureus, Staphylococcus epidermidis, Enterococcus faecalis, Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis. Amikacin-resistant Enterobacteriaceae often showed cross-resistance to ss-lactam antibiotics. Only 1% of the Escherichia coli isolates showed resistance to more than four antibiotics from a set of seven. This rate was higher for other Enterobacteriaceae and there were high levels of cross-resistance for P. aeruginosa. The cross-resistance of oxacillin with other antibiotics is well known in staphylococci. Penicillin-resistant pneumococcal isolates were cross-resistant to macrolides. Cross-resistance was only a minor problem in H. influenzae and M. catarrhalis. Cross- and multi-resistance are important problems for Gram-negative and Gram-positive bacteria but not for fastidious bacteria with the exception of penicillin-resistant S. pneumoniae.

We report a case of bacteremia due to Abiotrophia species in a patient with neutropenic fever and cancer who was receiving levofloxacin prophylaxis, followed by empirical therapy with cefepime; the organism was resistant to both antibiotics. We provide susceptibility data on 20 additional bloodstream isolates of Abiotrophia species.

The susceptibilities of 27 Abiotrophia adiacens (proposed reclassification Granulicatella adiacens comb.nov., Collins & Lawson, 2000) and 12 Abiotrophia defectiva isolates were tested by microdilution in pyridoxal hydrochloride and lysed horse blood supplemented Mueller-Hinton broth. According to NCCLS interpretative criteria for Streptococcus spp. not Streptococcus pneumoniae, the susceptibilities of A. adiacens and A. defectiva were, respectively: penicillin, 55% and 8%; amoxicillin, 81% and 92%; ceftriaxone, 63% and 83%; meropenem, 96% and 100%; and 100% for both species with clindamycin, rifampin, levofloxacin, ofloxacin, quinupristin/dalfopristin, and vancomycin.

Three cases of serious infection caused by Aerococcus urinae are presented: a patient with endocarditis and two patients with soft-tissue infection (phlegmon and balanitis respectively). The literature on Aerococcus urinae infections is reviewed and the antibiotic therapy discussed. Aerococcus urinae is a pathogen isolated primarily from urine specimens of elderly patients with local or systemic predisposing conditions. Most infections are mild, but serious infections such as endocarditis and septicemia/urosepsis have been described. Penicillin or ampicillin in combination with an aminoglycoside and close monitoring of the patient's clinical status and laboratory results would seem to be the best strategy for management of cases of serious infection.

Two cases of Aerococcus urinae endocarditis are reported. The organism is not included in any database of commercial identification systems at this time. Formation of tetrades and positive reactions for leucine arylamidase and beta-glucuronidase pointed strongly to A. urinae. The cellular fatty acid pattern was similar to that of Aerococcus viridans, with predominantly C16:0, C18:1 omega 9c and C18:0; the presence of C18:1 omega 7t differentiated our isolates from A. viridans and can support the diagnosis of A. urinae. Furthermore, susceptibility to penicillin but resistance to cotrimoxazole represents a pattern opposite to that of A. viridans. Minimal inhibition concentrations of gentamicin and netilmicin were < or = 64 mg/l but those of tobramycin were > or = 256 mg/l. Penicillin combined with either gentamicin or netilmicin showed distinct synergy in killing kinetics. These combinations seem to be the appropriate regimen to treat A. urinae endocarditis.

Two bacteriocinogenic strains of Pediococcus parvulus and one bacteriocinogenic Enterococcus mundtii strain were evaluated for their potential to control the growth of Listeria monocytogenes on refrigerated, modified atmosphere (MA) stored mungbean sprouts. These three strains, which were isolated from minimally-processed vegetables, were shown to grow in culture broth at 4, 8, 15 and 30 degrees C. However, only Ent. mundtii was capable of bacteriocin production at 4-8 degrees C. Examination of the growth of these strains on agar under 1.5% O2 in combination with 0, 5, 20 or 50% CO2 revealed significantly higher maximum specific growth rates for Ent. mundtii than for Pediococcus parvulus at CO2 concentrations below 20%, which are relevant for MA-storage of vegetables. Enterococcus mundtii was subsequently evaluated for its ability to control the growth of L. monocytogenes on vegetable agar and fresh mungbean sprouts under 1.5% O2/20% CO2/78.5% N2 at 8 degrees C. The growth of L. monocytogenes was inhibited by bacteriocinogenic Ent. mundtii on sterile vegetable-medium but not on fresh produce. However, mundticin, the bacteriocin produced by Ent. mundtii, was found to have potential as a biopreservative agent for MA-stored mungbean sprouts when used in a washing step or a coating procedure.

We characterized the regulated activity of the lactococcal nisA promoter in strains of the gram-positive species Streptococcus pyogenes, Streptococcus agalactiae, Streptococcus pneumoniae, Enterococcus faecalis, and Bacillus subtilis. nisA promoter activity was dependent on the proteins NisR and NisK, which constitute a two-component signal transduction system that responds to the extracellular inducer nisin. The nisin sensitivity and inducer concentration required for maximal induction varied among the strains. Significant induction of the nisA promoter (10- to 60-fold induction) was obtained in all of the species studied at a nisin concentration just below the concentration at which growth is inhibited. The efficiency of the nisA promoter was compared to the efficiencies of the Spac, xylA, and lacA promoters in B. subtilis and in S. pyogenes. Because nisA promoter-driven expression is regulated in many gram-positive bacteria, we expect it to be useful for genetic studies, especially studies with pathogenic streptococci in which no other regulated promoters have been described.

Helcococcus kunzii, a nonvirulent member of the human skin flora, has recently been implicated in causing infections in immunosuppressed patients. We report a case of breast abscess associated with H. kunzii in an immunocompetant patient and discuss the criteria used in its identification and our observations of susceptibility testing for this species.

Antimicrobial susceptibility of common bacterial species occurring on human skin appears to be falling. Data for the antimicrobial susceptibility of major groups of bacteria isolated from human skin during routine cultures were complied and analysed over a period of 9 months. Routine diagnostics of specimens from skin lesions and normal human skin were analysed for the presence of specified groups of bacteria. The species were identified using standard methods. Anti-microbial susceptibility was determined using a broth microdilution system giving breakpoints, the Sensititre system. Of the 333 Staphylococcus aureus, 129 Streptococcaceae, 180 Enterobacteriaceae and 120 Pseudomonadaceae strains investigated more than 5% of Staphylococcus aureus strains were resistant to flucloxacillin and thus methicillin (MRSA). More than 25% of Staphylococcus aureus strains were resistant to tetracycline and erythromycin. Many MRSA strains were found multi-resistant. Gentamicin was active against a large majority of Enterobacteriaceae strains but many Pseudomonadaceae strains were resistant. Compared with previous corresponding surveys methicillin-resistant Staphylococcus aureus strains are clearly on the increase. To prevent a further increase of resistant strains a defined strategy for antibiotic use is needed in dermatology.

LY191145 is an N-alkylated glycopeptide antibiotic (the p-chlorobenzyl derivative of LY264826) with activity against vancomycin-susceptible and -resistant bacteria. Similar to vancomycin, LY191145 inhibited polymerization of peptidoglycan when muramyl pentapeptide served as a substrate but not when muramyl tetrapeptide was used, signifying a substrate-dependent mechanism of inhibition. Examination of ligand binding affinities for LY191145 and the effects of this agent on R39 D,D-carboxypeptidase action showed that, similar to vancomycin, LY191145 had an 800-fold greater affinity for N,N'-diacetyl-L-Lys-D-Ala-D-Ala than for N,N'-diacetyl-L-Lys-D-Ala-D-Lac. The antibacterial activity of LY191145 was antagonized by N,N'-diacetyl-L-Lys-D-Ala-D-Ala, but the molar excess required for complete suppression exceeded that needed to suppress inhibition by vancomycin. LY191145 is strongly dimerized and the p-chlorobenzyl side chain facilitates interactions with bacterial membranes. These findings are consistent with a mechanism of inhibition where interactions between antibiotic and D-Ala-D-Ala or D-Ala-D-Lac residues depend on intramolecular effects occurring at the subcellular target site.

The purpose of this research was to investigate the salinity and formalin sensitivity of a ciliate parasite (Anophryoides haemophila) of the American lobster (Homarus americanus), and to examine the target-animal (lobster) safety of chemical-bath treatments involving low salinity, formalin, or chloramine-T that could be used to control this parasite in lobster pounds. "Bumper car" disease, caused by An. haemophila, is an important concern to lobster pound operators in eastern North America, because of the implicated lobster mortality rate and the general lack of preventive and therapeutic intervention regimes. We determined, using an in vitro method, that formalin at 50 mg/L, or low salinity at 8.0 parts per thousand (ppt) for 1 hour killed 100% of the parasites. When healthy lobsters were exposed to formalin at 200 mg/L, there were no negative behavioral responses and no significant differences in a panel of hemolymph biochemical indices. Similar results occurred when lobsters were exposed to chloramine-T, a common finfish therapeutic agent for topical bacteria and protozoa, at 10 mg/L for 1 hour. The low salinity treatment (8.0 ppt) resulted in significant adverse changes in lobster behavior and biochemical indices; however, these changes did not persist for more than 1 week after treatment ended. Although these treatments are unlikely to kill parasites that have already invaded the lobster carapace, they should be effective in reducing parasite loads on the gill and carapace surface of the lobster and in the environment of the impoundment housing.

Changes in fecal flora were evaluated in 22 healthy volunteers administered oral vancomycin or teicoplanin in 1989-1991 in Belgium. Evaluation of 5 colonies per subject revealed no glycopeptide-resistant enterococci in the predominant flora before glycopeptide administration; however, large numbers (mostly Enterococcus faecium) emerged by the end of the study in 14 (64%) of the subjects. Pediococci and lactobacilli also increased in number. In 1992, 40 healthy volunteers and 33 cancer patients were evaluated by plating stool samples directly onto selective media containing vancomycin; low numbers of vancomycin-resistant enterococci (< 50 cfu/g) were found in 11 (28%) of the 40 and 4 (12%) of the 33 samples, respectively. DNA restriction fragment length polymorphism analysis showed that most isolates were different, but all contained vanA in Tn1546-like elements. These results indicate that vanA and Tn1546-like elements were common in Belgium as early as 1989 and that community-based individuals in that location likely form a major reservoir for glycopeptide-resistant enterococci.

The biochemical basis for the acquired or natural resistance of various gram-positive organisms to glycopeptides was studied by high-pressure liquid chromatographic analysis of their peptidoglycan UDP-MurNAc-peptide precursors. In all cases, resistance was correlated with partial or complete replacement of the C-terminal D-Ala-D-Ala-containing UDP-MurNAc-pentapeptide by a new precursor with a modified C terminus. Nuclear magnetic resonance analysis by sequential assignment showed that the new precursor encountered in Enterococcus faecium D366, a strain belonging to the VANB class, which expresses low-level resistance to vancomycin, was UDP-MurNAc-L-Ala-gamma-D-Glu-L-Lys-D-Ala-D-lactate, identical to that previously found in the VANA class, which expresses high-level resistance to vancomycin. High-pressure liquid chromatographic analyses, composition determinations, and digestion by R39 D,D-carboxypeptidase demonstrated the exclusive presence of the new precursor in Lactobacillus casei and Pediococcus pentosaceus, which are naturally highly resistant to glycopeptides. The low-level natural resistance of Enterococcus gallinarum to vancomycin was found to be associated with the synthesis of a new precursor identified as a UDP-MurNAc-pentapeptide containing a C-terminal D-serine. The distinction between low and high levels of resistance to glycopeptides appeared also to depend on the presence or absence of a substantial residual pool of a D-Ala-D-Ala-containing UDP-MurNAc-pentapeptide.

(S)-3-(4-Methylsulfinylphenyl)-5-(acetamidomethyl)oxazolidinone (DuP 105; 1, R = CH3SO, R' = Ac), one of a new class of antibacterial agents, is shown to be devoid of inactivation and inhibitory properties toward bacterial cell wall biosynthesis and toward a beta-lactamase. This is consistent with the idea that this class of compounds acts by a route different from that of the beta-lactam antibiotics.

The formation of acceptor for the N epsilon-(D-Ala)-acceptor transpeptidase is an essential feature of nascent peptidoglycan processing. In Gaffkya homari the synthesis of cross-bridges in peptidoglycan includes a variety of penicillin-sensitive enzymes, e.g., transpeptidase, DD-carboxypeptidase, and LD-carboxypeptidase. To determine the primary target, we grew cultures in the presence of the MICs of benzylpenicillin (0.2 microgram/ml), methicillin (10 micrograms/ml), cephalothin (5 micrograms/ml), and cefoxitin (25 micrograms/ml) and examined the monomer-dimer composition of each peptidoglycan by high-performance liquid chromatography after muramidase digestion. From these studies it was recognized that of all the dimers, the synthesis of the predominant cross-bridge, diamidated octapeptide (-Ala-iso-D-Gln-Lys-D-Ala -Ala-iso-D-Gln-Lys-D-Ala), is most sensitive to the action of the beta-lactam at its MIC. The enhanced deamidation of the acceptor tetrapeptide, one of the substrates for the transpeptidase, is correlated with the inhibition of this cross-bridge. For example, at the MIC of benzylpenicillin, the ratio of amidated tetrapeptide to nonamidated tetrapeptide decreased from 2.8 in the control to 1.0 in the treated culture. From these results it would appear that a decrease in preferred acceptor for the transpeptidase results in the inhibition of synthesis of this major cross-bridge. Thus, the metabolism of the amide function of the monomer peptides may represent an additional feature of processing in the assembly of cross-bridged dimers in the peptidoglycan of this organism that is sensitive to the action of beta-lactam.

The minimum inhibitory concentration (MIC) of the new penem ALP 201 was tested against 243 recent clinical isolates of which 95 were from the family Enterobacteriaceae, 50 were from the genus Streptococcus, 50 were Staphylococcus aureus and 48 were Staphylococcus epidermidis. An agar dilution technique was used to determine the MIC50 and MIC90 of ALP 201 in comparison with cefotaxime, cefuroxime, clindamycin, imipenem, piperacillin, tobramycin and vancomycin. Overnight cultures were suspended to produce inocula of 10(5) colonies from a replicator. ALP 201 was shown to have an activity similar to imipenem against most species; ALP 201 was less active than imipenem against Serratia spp. and was more active against S. epidermidis. beta-Lactamase production did not affect the activity of ALP 201. All the other compounds tested were less active than ALP 201 and imipenem.

In this brief review of glycopeptides (teicoplanin and vancomycin) and lipoglycodepsipeptides (ramoplanin), comparison is made of their structure, general mode of action, specific target site and the mechanism by which inhibition of the sensitive enzyme is achieved. Although these two groups of antibiotics are chemically very different, they both inhibit late stages in the biosynthesis of bacterial cell wall peptidoglycan and cause the accumulation of the identical cell wall precursor, UDP-MurNAc-pentapeptide, in the cytoplasm. The specific target site is at the level of the membrane-bound enzymes which catalyse the attachment of wall precursors to a lipid carrier and subsequent polymerisation: ramoplanin inhibits transfer of one of the two precursors, whereas the glycopeptides block polymerisation. As different targets are involved, cross-resistance between glycopeptides and ramoplanin is unlikely and has not yet been reported. The actual mechanisms of action are totally different: glycopeptides inhibit the sensitive reaction by binding firmly, as a result of substantial hydrogen bonding, to acyl-D-Ala-D-Ala termini of the nascent peptidoglycan chains or lipid-linked wall subunits. The substrate is sequestered in a cleft of the antibiotic molecule and cannot interact with the polymerase enzyme. The precise mechanism of action of ramoplanin has not been elucidated, but its action is not dependent on the presence of the acyl-D-Ala-D-Ala group in the substrate and its binding characteristics are different from those of the glycopeptides. It therefore has a different mechanism of action as well as a different site, compared with the glycopeptides.

Vancomycin inhibits the synthesis of peptidoglycan in membrane preparations from Gaffkya homari with uridine diphosphate-N-acetylmuramyl (UDP-Mur-NAc)-pentapeptide as substrate, but not with either UDP-MurNAc-tetrapeptide or UDP-MurNAc-tripeptide. These results are correlated with the specificity studies described by Perkins and Nieto for complex formation between the antibiotic and the peptide subunit. It is concluded that the formation of a complex between vancomycin and a postulated cell wall acceptor or between vancomycin and the enzymes involved in peptidoglycan synthesis does not contribute to the inhibitory action of this antibiotic. The mechanism of vancomycin action on peptidoglycan synthesis is clearly different from that of moenomycin and bacitracin. In the presence of these antibiotics, peptidoglycan synthesis is inhibited with both UDP-MurNAc-pentapeptide and -tetrapeptide as substrates. In addition, these results provide additional insight into the mechanism of phospho-MurNAc-pentapeptide translocase. For example, enhancement of the transfer of phospho-MurNAc-peptide from UDP-MurNAc-peptide to undecaprenyl-phosphate at low concentrations of vancomycin is observed with UDP-MurNAc-pentapeptide and not with -tetrapeptide. Complexation of vancomycin with undecaprenyl-diphosphate-MurNAc-pentapeptide, resulting in an ineffective intermediate, would increase the rate of transfer by preventing the reassociation of undecaprenyl-diphosphate-MurNAc-pentapeptide with the enzyme.

A previous study of the aerotolerant bacterium Lactobacillus plantarum, which lacks superoxide dismutase (SOD), demonstrated that it possesses a novel substitute for this defensive enzyme. Thus, L. plantarum contains 20 to 25 mM Mn(II),m in a dialyzable form, which is able to scavenge O2- apparently as effectively as do the micromolar levels of SOD present in most other organisms. This report describes a survey of the lactic acid bacteria. The substitution of millimolar levels of Mn(II) for micromolar levels of SOD is a common occurrence in this group of microorganisms, which contained either SOD or high levels of Mn(II), but not both. Two strains were found which had neither high levels of Mn(II) nor SOD, and they were, as was expected, very oxygen intolerant. Lactic acid bacteria containing SOD grew better aerobically than anaerobically, whereas the organisms containing Mn(II) in place of SOD showed aerobic growth which was best, at best, equal to anaerobic growth. Plumbagin (5-hydroxy-2-methyl-1,4-naphthoquinone) increases the rate of O2- production in these organisms. Lactobacillus strains containing high intracellular Mn(II) were more resistant to the oxygen-dependent toxicity of plumbagin than were strains containing lower levels of Mn(II). The results support the conclusion that a high internal level of Mn(II) provides these organisms with an important defence against endogenous O2-.