Cell Based Drug Delivery: Micrococcus luteus Loaded Neutrophils as Chlorhexidine Delivery Vehicles in a Mouse Model of Liver Abscesses in Cattle

The recent WHO report on antibiotic resistances shows a dramatic increase of microbial resistance against antibiotics. With only a few new antibiotics in the pipeline, a different drug delivery approach is urgently needed. We have obtained evidence demonstrating the effectiveness of a cell based drug delivery system that utilizes the innate immune system as targeting carrier for antibacterial drugs. In this study we show the efficient loading of neutrophil granulocytes with chlorhexidine and the complete killing of E. coli as well as Fusobacterium necrophorum in in-vitro studies. Fusobacterium necrophorum causes hepatic abscesses in cattle fed high grain diets. We also show in a mouse model that this delivery system targets infections of F. necrophorum in the liver and reduces the bacterial burden by an order of magnitude from approximately 2•106 to 1•105.

Importance of blood cultures to aid the diagnosis of Lemierre's syndrome

This is a case report of Lemierre's syndrome, a septic thrombophlebitis of the internal jugular vein (IJV) usually preceded by pharyngitis and bacteraemia with an anaerobic organism. Fusobacterium necrophorum is ananaerobic Gram-negative bacillus and is the most common organism reported to cause Lemierre's syndrome which usually occurs one to three weeks post pharyngitis or oropharyngeal surgery. A 21-year-old patient presented with signs of sepsis and a history of sore throat, fever, and tender cervical lymph nodes. Blood cultures grew F. necrophorum and Computed Tomography (CT) showed a filling defect in the left retromandibular vein and thrombosis in the left internal jugular vein (IJV) consistent with Lemierre's syndrome. This is an uncommon condition which normally occurs in young individuals and diagnosis is often delayed.

Lemierre's syndrome: Still an important clinical entity

We report a case of Lemierre's syndrome caused by Fusobacterium necrophorum and discuss characteristics of this potentially fatal condition which, though rare, may have a rising frequency. Familiarity with the signs and symptoms of Lemierre's syndrome is therefore of great importance.

An unusual case of Lemierre's syndrome presenting as pyomyositis

Fusobacteria are most often associated with the classic presentation of Lemierre's syndrome consisting of a sore throat, internal jugular vein thrombophlebitis, and septic emboli to the lungs. Unusual presentations due to the causative organism, F. necrophorum, may occur. We present such a case involving a 17-year-old male patient with pyomyositis and fasciitis due to necrobacillosis. Fusobacterium spp. should be considered in the differential diagnosis of cases involving sepsis syndrome and pyomyositis.

Human infection with Fusobacterium necrophorum (Necrobacillosis), with a focus on Lemierre's syndrome

Human infection with Fusobacterium necrophorum usually involves F. necrophorum subsp. funduliforme rather than F. necrophorum subsp. necrophorum, which is a common pathogen in animals. Lemierre's syndrome, or postanginal sepsis, is the most common life-threatening manifestation. Tonsillitis is followed by septic thrombophlebitis of the internal jugular vein and then a septicemia with septic emboli in lungs and other sites. Recent evidence suggests that F. necrophorum can be limited to the throat and cause persistent or recurrent tonsillitis. F. necrophorum is unique among non-spore-forming anaerobes, first for its virulence and association with Lemierre's syndrome as a monomicrobial infection and second because it seems probable that it is an exogenously acquired infection. The source of infection is unclear; suggestions include acquisition from animals or human-to-human transmission. Approximately 10% of published cases are associated with infectious mononucleosis, which may facilitate invasion. Recent work suggests that underlying thrombophilia may predispose to internal jugular vein thrombophlebitis. Lemierre's syndrome was relatively common in the preantibiotic era but seemed to virtually disappear with widespread use of antibiotics for upper respiratory tract infection. In the last 15 years there has been a rise in incidence, possibly related to restriction in antibiotic use for sore throat.

Effects of feeding polyclonal antibody preparations on ruminal bacterial populations and ruminal pH of steers fed high-grain diets

Three experiments with factorial arrangements of treatments were designed to test the efficacy of avian-derived polyclonal antibody preparations (PAP) against Streptococcus bovis (PAP-Sb) or Fusobacterium necrophorum (PAP-Fn) in reducing ruminal counts of target bacteria in beef steers supplemented or not with feed additives (300 mg of monensin/d and 90 mg of tylosin/d; MT). Feeding increasing doses of PAP-Sb in Exp. 1 or a single dose in Exp. 2 reduced S. bovis counts in a cubic fashion (P = 0.014). In Exp. 1 and 2, inclusion of MT in the diet had no effect (P > 0.05) on ruminal S. bovis counts. In Exp. 2, ruminal pH was increased (P < 0.05) by feeding PAP-Sb, MT, and PAP-Sb plus MT. Ruminal F. necrophorum counts were reduced by feeding PAP-Fn (P = 0.002) and MT (P < 0.001). Reduction in ruminal F. necrophorum counts was greater (P = 0.008) when feeding MT alone than when feeding PAP-Fn and MT together. In Exp. 3, ruminal S. bovis counts were not affected (P = 0.64) by PAP-Fn. Ruminal pH was not affected (P = 0.61) by feeding PAP-Fn, and the total anaerobic bacterial count was not affected (P > 0.05) by either PAP-Sb or PAP-Fn in Exp. 1 or Exp. 3. In conclusion, PAP of avian origin and against S. bovis or F. necrophorum were effective in reducing target ruminal bacterial populations. These PAP could be effective in preventing the deleterious effects associated with these bacteria, and possibly in enhancing animal performance.

[Inhibition of extracts from 17 Chinese herbs on periodontal pathogenic microbes]

PURPOSE

To evaluate the efficiency of 17 Chinese herbs on periodontal pathogenic microbes.

METHODS

17 efficient substances from Chinese herbs were purchased from Chinese Drug Identification Bureau, including magnesium lithospermate B, magnolol, tetramethyl pyrazine, matrine, dycyrrhizin, gentiopicrin, aloperin, baicalin, oleanolic acid, ginkgo seed, total glucosides of paeony capsules, anisldehyde, archin, cablin patchouli, hydrochloric acid Berberine, forsythin, and kakonein. Antimicrobial sensitivity tests of broth microdilution methods on 96-microwell plate were carried out for identification of the antimicrobial activity of extracts against six species of microorganisms: Actinobacillus actinomycete mitans(Aa) Y4, Actinomycetes viscosus(Av) 19246, Porphyromonas gingivalis(Pg) 33277, Fusobacterium necrophorum(Fn) 25286, Actinomyces naeslundii(An) wvl 45 and Prevotella nigrescens(Pn).

RESULTS

It was found that magnesium lithospermate B and magnolol showed the most efficient inhibition on microorganism of Pn and Fn, with the MIC being 0.053 and 0.313 mg/ml for Pn and Fn, respectively. Tetramethyl pyrazine, matrine, dycyrrhizin, gentiopicrin, aloperin, baicalin, and oleanolic acid had better inhibition than total glucosides of paeony capsules, anisldehyde, archin, cablin patchouli, hydrochloric acid berberine, forsythin, and kakonein.

CONCLUSION

The Chinese herbs, magnesium lithospermate B and magnolol are efficient agents for inhibition against periodontal pathogenic microbes.

Influence of flavomycin on ruminal fermentation and microbial populations in sheep

Flavomycin is a phosphoglycolipid antibiotic that promotes growth in ruminants. The aim of this study was to characterize the effects of flavomycin on ruminal micro-organisms and their metabolic consequences. In sheep receiving a mixed grass hay/concentrate diet, inclusion of 20 mg flavomycin day(-1) decreased ruminal ammonia and total volatile fatty acid concentrations (P<0.001), but the acetate : propionate ratio was unchanged. Ruminal pH tended to be lower with flavomycin, and ammonia-production rates of ruminal digesta from control animals measured in vitro tended to be inhibited by flavomycin. Pure-culture studies indicated that anaerobic fungi, protozoa and most bacterial species were insensitive to flavomycin. Fusobacterium necrophorum was the most sensitive species tested, along with some high-activity ammonia-producing (HAP) species. Effects on F. necrophorum in vivo were inconsistent due to large inter-animal variation. HAP numbers appeared to be decreased. Changes in the rumen bacterial-community structure were assessed by using denaturing-gradient gel electrophoresis (DGGE) analysis of rumen digesta 16S rRNA. DGGE profiles differed from animal to animal, but remained consistent from day to day. The community structure changed when flavomycin was introduced. The roles of F. necrophorum and HAP species in ammonia formation and of F. necrophorum in the invasion of wall tissue are consistent with the observed effects of flavomycin on ruminal ammonia formation and, in other studies, on decreasing tissue-turnover rates.

Minimum inhibitory concentrations of some antimicrobial drugs against bacteria causing uterine infections in cattle

The minimum inhibitory concentrations (MICs) of oxytetracycline, cephapirin, cephapirin/mecillinam, cefquinome, ceftiofur and enrofloxacin, candidate antibiotics for the principal bacteria associated with uterine infections: Escherichia coli, Arcanobacterium pyogenes and the anaerobic bacteria Fusobacterium necrophorum and Prevotella melaninogenicus, were determined by the agar dilution method. The bacteria were isolated from animals with clinical metritis and/or endometritis. For E coli, cefquinome and enrofloxacin had the lowest MIC90 and MIC50 values (< 0.06 microg/ml), and oxytetracycline and cephapirin had the highest values. For A pyogenes, oxytetracycline had the highest MIC50 value (16 microg/ml), but all the cephalosporins had values below 0.06 microg/ml. For the anaerobic bacteria, enrofloxacin and oxytetracycline had the highest MIC50 values but all the cephalosporins had values of 0.06 microg/ml or below.

Bacteriological study of root canals associated with periapical abscesses

OBJECTIVE

The aim of this study was to identify microorganisms from root canals with periapical abscesses and to ascertain the susceptibility of Peptostreptococcus prevotii and Fusobacterium necrophorum to antimicrobials. Study design Thirty root canals were microbiologically sampled by using sterile paper points. The concomitant microorganisms were identified through the use of established methods. The susceptibility of P prevotii and F necrophorum to antimicrobials was evaluated by using the E test method.

RESULTS

A total of 117 different bacterial strains were recovered, including 75 strict anaerobes or microphilic species. The most frequently isolated strict anaerobes were P prevotii, Peptostreptococcus micros, and F necrophorum. Facultative bacteria such as Gemella morbillorum and Streptococcus mitis were also found, albeit less frequently. The data revealed that P prevotii and F necrophorum were susceptible to the tested antibiotics.

CONCLUSIONS

Gram-positive anaerobic bacteria predominate in the mixed microbiota of root canals with periapical abscesses. Moreover, P prevotii and F necrophorum are susceptible to the tested antibiotics.

Fusobacterium necrophorum infections in England and Wales 1990-2000

In response to a marked increase in both the number of Fusobacterium necrophorum bacteraemia reports to the PHLS Communicable Disease Surveillance Centre and the number of F. necrophorum isolates referred to the PHLS Anaerobe Reference Unit in 1999, the data from both sources on F. necrophorum infections were reviewed for the decade 1990-2000. There were 208 reports of F. necrophorum bacteraemia (average 19/year; range 14-34/year) with a peak in incidence in the late winter months; 68% were from male patients and the peak age range was 16-23 years. Of 205 referred isolates of F. necrophorum, 122 (59%) were from blood cultures and these represented 58% of the bacteraemia reports; the others were from brain and soft tissue abscesses, pleural and joint fluids, eyes, ears and lymphatic tissue. The average number of referrals was 19/year (range 9-37/year). The peak year for bacteraemia reports (34) and isolate referrals (37) was 1999; this increase was not sustained in 2000. All isolates were susceptible to metronidazole, but 2% were resistant to penicillin and 15% to erythromycin. F. necrophorum continues to be a regular but uncommon cause of bacteraemia and metastatic abscesses following an acute sore throat, especially in young, otherwise healthy adults.

Effects of tylosin on concentrations of Fusobacterium necrophorum and fermentation products in the rumen of cattle fed a high-concentrate diet

OBJECTIVE

To determine effects of tylosin on ruminal concentrations of Fusobacterium necrophorum and fermentation products in cattle during rapid adaptation to a high-concentrate diet.

ANIMALS

6 steers fitted with ruminal cannulas.

PROCEDURE

Steers were assigned randomly to 2 treatment groups and switched from a 0 to an 85% concentrate diet during a 4-day period. Cattle received this diet, with or without tylosin (90 mg/steer/d), for 4 weeks. Samples of ruminal contents were collected daily beginning 2 days before the treatment protocol and in the first week of concentrate feeding. Four subsequent samples were collected at weekly intervals. Concentration of F. necrophorum in samples was determined, using the most-probable-number technique. Ruminal pH and concentrations of volatile fatty acids (VFA), lactate, and ammonia also were determined. All steers received both treatments separated by 4 weeks (cross-over design), during which time they were fed alfalfa hay only.

RESULTS

In control steers, concentration of F. necrophorum increased in response to the high-concentrate diet. Tylosin-fed steers had lower concentrations of F. necrophorum than control steers at all times during concentrate feeding. However, ruminal pH and concentrations of lactate, VFA, and ammonia did not differ between treatment groups.

CONCLUSIONS AND CLINICAL RELEVANCE

Tylosin caused a significant reduction in ruminal concentrations of F. necrophorum during rapid adaptation to a high-concentrate diet but had no effect on fermentation products. The reduction in ruminal concentration of F. necrophorum helps explain the reduction in prevalence of hepatic abscesses reported in tylosin-fed feedlot cattle.

Isolation of Fusobacterium necrophorum from cancrum oris (noma)

A study of the predominant microflora in active sites of noma (cancrum oris) lesions was carried out in eight noma patients 3-15 years of age in Sokoto State in northwestern Nigeria. Paper point sampling and conventional anaerobic microbiologic techniques were used. Fusobacterium necrophorum was recovered from 87.5% of the noma lesions. Oral microorganisms included Prevotella intermedia, alpha-hemolytic streptococci, and Actinomyces spp. which were isolated from 75.0%, 50.0%, and 37.5% of the patients, respectively. Peptostreptococcus micros, Veillonella parvula, Staphylococcus aureus, and Pseudomonas spp. were each recovered from one lesion. The F. necrophorum and P. intermedia isolates were tested for antibiotic sensitivity to clindamycin, tetracycline, metronidazole, and penicillin using the E-test, and all strains were observed to be sensitive to all of the antibiotics tested with the exception of one strain of P. intermedia, which showed resistance to penicillin. The first reported isolation from human noma lesions of F. necrophorum, a pathogen primarily associated with animal diseases, may have important etiologic and animal transmission implications.

Antimicrobial susceptibility of Fusobacterium necrophorum isolated from bovine hepatic abscesses

OBJECTIVE

To determine the resistance and susceptibility to antimicrobial compounds of Fusobacterium necrophorum isolates from bovine hepatic abscesses.

PROCEDURE

37 isolates of F necrophorum (21 subsp necrophorum and 16 subsp funduliforme) isolated from bovine hepatic abscesses were obtained from cultures grown and maintained in anaerobic brain heart infusion broth. A broth dilution method was used as an initial screening to determine general susceptibility to 31 antimicrobial compounds. The minimal inhibitory concentrations (MIC) of 19 of the antimicrobial compounds that inhibited growth in the initial test were determined by use of the broth microdilution method.

RESULTS

Fusobacterium necrophorum isolates were generally susceptible to penicillins, tetracyclines (chlortetracycline and oxytetracycline), lincosamides (clindamycin and lincomycin), and macrolides (tylosin and erythromycin), and were resistant to aminoglycosides (kanamycin, neomycin, gentamicin, and streptomycin), ionophores (except narasin), and peptides (avoparcin, polymyxin, and thiopeptin). The 5 antimicrobials (bacitracin, chlortetracycline, oxytetracycline, tylosin, and virginiamycin) that have FDA approval for prevention of liver abscesses in feedlot cattle were inhibitory to F necrophorum. Differences in antimicrobial susceptibility patterns were observed between the 2 subspecies only for clindamycin and lincomycin. The MIC of F necrophorum isolates from antibiotic-fed cattle were similar to those for isolates from nonantibiotic-fed cattle.

CONCLUSIONS

The MIC of FDA-approved antibiotics were not reflective of the efficacy of antibiotics in preventing liver abscesses in feedlot cattle. Also, continuous feeding of tylosin did not appear to select resistant F necrophorum.

Minimum inhibitory concentrations for selected antimicrobial agents against Fusobacterium necrophorum isolated from hepatic abscesses in cattle and sheep

Minimum inhibitory concentrations for 35 antimicrobial agents against 100 Fusobacterium necrophorum isolates from hepatic abscesses in sheep and cattle were determined. Twelve of the thirteen beta-lactam antibiotics tested inhibited growth of 100% of strains tested. Of the remaining antimicrobial agents, extensive susceptibility was found for: spiramycin, josamycin, lincomycin, tylosin, oxytetracycline, chlortetracycline, rufloxacin, metronidazole, cotrimoxazole, sulfadimethoxine, virginiamycin and fosfomycin.

The effect of cyclosporin-A on the oral microflora at gingival sulcus of the ferret

The effect of cyclosporin-A (CyA) on the dentogingival flora of ferrets with healthy and experimentally induced periodontal breakdown was studied. Five animals were given 10 mg/kg/d CyA. At the start of the experiments (day 0), ligatures were placed around 4 teeth in the right upper and lower jaws; corresponding contralateral teeth on the left side served as control. On days 0 and 28 (end of the experiment), microbiological samples were collected from the gingival sulcus of the experimental and the control teeth and from closely located gingival mucosa membrane. The samples were subjected to viable counts and to darkfield microscopic analyses. On day 0, facultative anaerobic rods, mainly Pasteurella spp, Alcaligenes spp, Corynebacterium spp. and Rothia spp dominated in the viable counts. No anaerobic bacteria were detected in the viable counts. On day 28 spirochetes increased in the experimental gingival sulcus samples and anaerobic bacteria appeared in most of the samples and constituted 40-60% of the total cultivable flora; Fusobacterium necrophorum and Eubacterium spp. predominated in the samples from the experimental sites. The results of the present study were compared with those of our previous investigation of ferrets not medicated with cyclosporin but also subject to experimental ligature periodontitis. Eubacterium spp. were absent in the animals not treated with cyclosporin, while this species was frequently present in the immunosuppressed ferrets. The results indicate that the presence of the large numbers of gram negative rods and of anaerobic bacteria may have enhanced the inflammatory process and further provoked the gingival overgrowth observed.

Biochemical and biological characterization of ruminal Fusobacterium necrophorum

Biochemical characteristics, biological activities, and antimicrobial susceptibilities of ruminal Fusobacterium necrophorum (eight subsp. necrophorum and eight subsp. funduliforme) and of isolates (three of each subsp.) obtained from bovine hepatic abscesses were determined. F. necrophorum subsp. necrophorum strains had higher phosphatase and DNase activities, produced more leukotoxin, and were more pathogenic to mice than subsp. funduliforme strains. The leukotoxin titer for culture supernatants of ruminal subsp. necrophorum strains was approximately 15 times lower than that of hepatic subsp. necrophorum strains. Hemagglutination activity was present in all hepatic, but only in some ruminal, strains of subsp. necrophorum. The antimicrobial sensitivity profile of the ruminal isolates was similar to that of hepatic isolates.

Effect of disturbance of the gastrointestinal microflora on the faecal excretion of Fusobacterium necrophorum biovar A

Oral pretreatment of mice with either a mixture of kanamycin and erythromycin or metronidazole to modify the gut microflora greatly enhanced the faecal excretion of Fusobacterium necrophorum biovar A given by mouth. This lends support to the suggestion that disturbance of the gastrointestinal microflora in animals such as cattle, which often carry the organism in the rumen, may lead to intestinal multiplication and faecal excretion, thereby providing a source of infection that may lead to necrobacillosis of the body surface.

The relationship between Fusobacterium species and other flora in mixed infection

Mixed infections with three Fusobacterium species and seven other bacterial species were studied in a subcutaneous abscess model in mice. Fifteen Fusobacterium isolates (eight F. nucleatum, four F. necrophorum, and three F. varium) and one isolate each of Bacteroides fragilis, B. asaccharolyticus, Staphylococcus aureus, Group A beta-haemolytic streptococcus, Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa were studied. Electronmicrographs showed the presence of a thin mucopolysaccharide wall before and after inoculation into mice in 12 isolates which included all of 11 Fusobacterium isolates that induced subcutaneous abscesses. After co-inoculation of Fusobacterium isolates with other species and selective therapy with antimicrobial agents, S. aureus and K. pneumoniae were found to be of equal or greater importance in abscess induction than were Fusobacterium isolates, while Fusobacterium isolates were found to be more important than Group A streptococci and E. coli. Mutual enhancement of the numbers of organisms in mixed infections was observed with Fusobacterium spp. and K. pneumoniae, P. aeruginosa or Bacteroides spp. Suppression of Fusobacterium spp. was noticed only when they were co-inoculated with Group A streptococci. The additive or synergistic capabilities of Fusobacterium species highlighted their potential pathogenicity in infection.

Studies of Fusobacterium necrophorum from bovine hepatic abscesses: biotypes, quantitation, virulence, and antibiotic susceptibility

Isolates of Fusobacterium necrophorum were obtained from 124 bovine hepatic abscesses (in 119 cattle) and from the ruminal contents of 12 cattle. Three biotypes (A, AB, and B) were found. Type A isolates were most common in hepatic abscesses, and type B isolates were most common in ruminal contents. Virulence studies in mice indicated that type A isolates were more pathogenic than types AB or B isolates. The difference in virulences between types A and B isolates was not related to the toxicity of the endotoxin. Results of serotesting (passive hemagglutination) showed that a wide heterogeneity existed between isolates. Minimal inhibitory concentrations of antibiotics for 12 of the isolates (7 type A, 1 type AB, and 4 type B) were as follows: less than or equal to 0.06 IU of penicillin G/ml; less than or equal to 0.5 micrograms of cephaloridine/ml; less than or equal to 2 micrograms of chloramphenicol/ml; less than or equal to 0.06 micrograms of clindamycin/ml; less than or equal to 8 micrograms of erythromycin/ml; less than or equal to 128 micrograms of gentamicin/ml; less than or equal to 0.25 micrograms of oxytetracycline/ml; and less than or equal to 4 micrograms of tylosin/ml.

[Fusobacterium necrophorum associated with Actinomyces odontolyticus septicemia ]

The authors have observed a case of Fusobacterium necrophorum associate with Actinomyces odontolyticus septicemia, which appears to be the first case reported. In a 19 year old man, 15 blood cultures allowed to isolate both germs. Clinical manifestations were: acute-like abdomen, encephalitis, myocarditis and pleural effusion. Treatment with amoxicillin and metronidazole was successful.

Gram-negative anaerobic bacilli: Their role in infection and patterns of susceptibility to antimicrobial agents. II. Little-known Fusobacterium species and miscellaneous genera

Twenty infrequently reported species of gram-negative anaerobic bacilli other than Fusobacterium nucleatum, Fusobacterium necrophorum, and members of the genus Bacteroides were studied with regard to their role in infection and their susceptibility to antimicrobial agents. In addition, the literature regarding the recovery of these organisms from both the normal flora and infections of humans was reviewed. During a six-year period at the Wadsworth Clinical Anaerobic Bacteriology Research Laboratory (Veterans Administration Wadsworth Medical Center, Los Angeles, Calif.), 39 (6%) of 679 specimens obtained from anaerobic infections yielded "other gram-negative anaerobic bacilli" (OGNAB). Fusobacterium naviforme, Fusobacterium gonidiaformans, Fusobacterium varium, Fusobacterium mortiferum, and Fusobacterium russii were the most commonly isolated OGNAB. Most of the OGNAB tested were resistant to erythromycin, and most strains, except for F. varium, were susceptible to beta-lactam antibiotics and clindamycin. Chloramphenicol and metronidazole were active against all strains of OGNAB tested. Certain Fusobacterium species are undoubtedly previously unrecognized members of the normal flora of the oropharynx, upper respiratory tract, or urogenital tract and may be present in infections derived from these floras.

Susceptibility of Fusobacterium necrophorum to antimicrobials. Part I: as determined by the disc method

The susceptibility of 25 isolates of Fusobacterium necrophorum to 37 antimicrobials was tested using the disc method. F. necrophorum was susceptible to 15 antimicrobials, resistant to 12. To the remaining ten antimicrobials some isolates were completely resistant whereas others showed partial resistance.