Clinical spectrum of bacteraemic Fusobacterium infections: from septic shock to nosocomial bacteraemia.

BACKGROUND: Fusobacterium species are anaerobic bacteria that relatively rarely cause sepsis with a variable clinical presentation. METHODS: We reviewed the records of 52 consecutive patients who had Fusobacterium bacteraemia over a 10-y period. RESULTS: The clinical pictures could be classified into 4 groups: (1) patients who had Lemierre's syndrome with Fusobacterium necrophorum sepsis and internal jugular vein thrombosis, n = 5 (10%); (2) previously healthy patients who had F. necrophorum sepsis without any signs of macroscopic vascular thrombosis (but 5 of them had abscesses), n = 14 (27%); (3) women who had puerperal infections, n = 6 (12%); and (4) patients who were on average older than the patients in the previous groups, who had cardiovascular, pulmonary, neoplastic, or other underlying diseases, n = 27 (52%). Of these latter 27 patients, 23 had nosocomial Fusobacterium nucleatum bacteraemia presenting as a febrile illness associated with chemotherapy or instrumentation. CONCLUSIONS: Patients with chronic underlying diseases are more likely to be infected with F. nucleatum than F. necrophorum. F. nucleatum bacteraemia may present as a febrile illness without severe symptoms. F. necrophorum caused sepsis mainly in previously healthy individuals. These infections may be accompanied with a jugular vein thrombosis characteristic of Lemierre's syndrome and septic shock. However, F. necrophorum infections present more frequently without any apparent venous thrombosis and may be accompanied by abscesses.

Phospholipase D promotes Arcanobacterium haemolyticum adhesion via lipid raft remodeling and host cell death following bacterial invasion.

BACKGROUND: Arcanobacterium haemolyticum is an emerging bacterial pathogen, causing pharyngitis and more invasive infections. This organism expresses an unusual phospholipase D (PLD), which we propose promotes bacterial pathogenesis through its action on host cell membranes. The pld gene is found on a genomic region of reduced %G + C, suggesting recent horizontal acquisition. RESULTS: Recombinant PLD rearranged HeLa cell lipid rafts in a dose-dependent manner and this was inhibited by cholesterol sequestration. PLD also promoted host cell adhesion, as a pld mutant had a 60.3% reduction in its ability to adhere to HeLa cells as compared to the wild type. Conversely, the pld mutant appeared to invade HeLa cells approximately two-fold more efficiently as the wild type. This finding was attributable to a significant loss of host cell viability following secretion of PLD from intracellular bacteria. As determined by viability assay, only 15.6% and 82.3% of HeLa cells remained viable following invasion by the wild type or pld mutant, respectively, as compared to untreated HeLa cells. Transmission electron microscopy of HeLa cells inoculated with A. haemolyticum strains revealed that the pld mutant was contained within intracellular vacuoles, as compared to the wild type, which escaped the vacuole. Wild type-infected HeLa cells also displayed the hallmarks of necrosis. Similarly inoculated HeLa cells displayed no signs of apoptosis, as measured by induction of caspase 3/7, 8 or 9 activities. CONCLUSIONS: These data indicate that PLD enhances bacterial adhesion and promotes host cell necrosis following invasion, and therefore, may be important in the disease pathogenesis of A. haemolyticum infections.

Dysgonomonas hofstadii sp. nov., isolated from a human clinical source.

A Gram-negative staining, facultative anaerobic, cocco-bacillus-shaped organism was isolated from a post-operative abdominal wound. Based on morphological and biochemical criteria, strain MX 1040 (=CCUG 54731(T)) was tentatively identified as Bacteroidaceae but did not correspond to any recognized species of this family. Comparative 16S rRNA gene sequencing analysis demonstrated the organism to be related to species of the genus Dysgonomonas, although sequence divergence values of >5% with the other members of this genus demonstrated the organism to represent a novel species. Phylogenetic analysis revealed the novel organism to be most closely related to Dysgonomonas gadei. The major long-chain cellular fatty acids of the novel species consisted of iso-C(14:0), anteiso-C(15:0), C(16:0), and iso-C(16:0). Based on the phenotypic criteria and phylogenetic considerations, it is proposed that strain MX 1040 from a human clinical source represents a new species of the genus Dysgonomonas, as Dysgonomonas hofstadii sp. nov. The type strain of D. hofstadii is CCUG 54731(T) (=CCM 7606(T)).

Factor H binding as a complement evasion mechanism for an anaerobic pathogen, Fusobacterium necrophorum.

Fusobacterium necrophorum subspecies funduliforme is an obligate anaerobic Gram-negative rod causing invasive infections such as the life-threatening Lemierre's syndrome (sore throat, septicemia, jugular vein thrombosis, and disseminated infection). The aim of our study was to understand if and how F. necrophorum avoids C activation. We studied 12 F. necrophorum subsp. funduliforme strains isolated from patients with sepsis. All strains were resistant to serum killing after a 1-h incubation in 20% serum. The bacteria bound, at different levels, the C inhibitor factor H (fH). Binding was ionic and specific in nature and occurred via sites on both the N terminus and the C terminus of fH. Bound fH remained functionally active as a cofactor for factor I in the cleavage of C3b. Interestingly, patients with the most severe symptoms carried strains with the strongest ability to bind fH. An increased C3b deposition and membrane attack complex formation on the surface of a weakly fH-binding strain was observed and its survival in serum at 3.5 h was impaired. This strain had not caused a typical Lemierre's syndrome. These data, and the fact that fH-binding correlated with the severity of disease, suggest that the binding of fH contributes to virulence and survival of F. necrophorum subsp. funduliforme in the human host. Our data show, for the first time, that an anaerobic bacterium is able to bind the C inhibitor fH to evade C attack.

Faecal antigen tests in the confirmation of the effect of Helicobacter eradication therapy.

BACKGROUND: The frequent occurrence of Helicobacter pylori infection requires significant health care resources after eradication therapy. Therefore the non-invasive testing methods are required to alleviate the increased work-load of health care personnel and to allow an easy control of eradication therapy. Conventionally, the effect of eradication therapy has been confirmed with 13C-urea breath test 4-6 weeks after a completed eradication. AIM: To assess the applicability of Helicobacter pylori stool antigen tests as alternatives to the breath test in the control of the effect of eradication therapy. METHODS: Fifty patients were diagnosed Helicobacter-positive by endoscopy and histology as well as by rapid urease test from mucosal specimen. Four weeks after an eradication therapy the patients were subjected to 13C-urea breath test as well as to faecal Helicobacter pylori antigen tests with mono- and polyclonal primary antibodies. RESULTS: The monoclonal and polyclonal stool tests had 94% and 88% sensitivity, and 100% and 97% specificity, respectively, in the detection of Helicobacter pylori infection as compared to the 13C-urea breath test. The non-invasive test results were completely parallel in patients with various grades of mucosal atrophy or intestinal metaplasia. CONCLUSIONS: Monoclonal faecal Helicobacter pylori antigen test is slightly superior to the polyclonal test regarding the sensitivity in the detection of stool Helicobacter antigens. Due to their sufficient sensitivity and specificity, and to their practicability and cost-effectiveness, they can be recommended for non-invasive testing of Helicobacter pylori infection as alternatives to the 13C-urea breath test.

Induction of CD69 expression and Th1 cytokines release from human peripheral blood lymphocytes after in vitro stimulation with Alloiococcus otitidis and three middle ear pathogens.

Alloiococcus otitidis is a recently discovered pathogen of otitis media. However, only a limited number of studies are available about the pathogenic and immunological role of A. otitidis. The aim of this study was to investigate the activation and the cytokine production of human peripheral blood lymphocytes at the early immune response after stimulation with A. otitidis. After stimulation of whole human peripheral blood lymphocytes for 18 h with whole killed A. otitidis or the three major middle ear pathogens (Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis), the expression of CD69 and the production of cytokines were analyzed. The expression of CD69 on T cells and B cells was dose-dependently enhanced after stimulation with A. otitidis. The release of interleukin (IL)-12 was induced after stimulation with A. otitidis, whereas the release of IL-4 was not induced after stimulation with A. otitidis. In addition, the release of interferon (IFN)-gamma was induced after stimulation with A. otitidis. Although the release of IFN-gamma started within 18 h after stimulation with A. otitidis, intracellular production of IFN-gamma was not observed in either CD4+ T cells or CD8+ T cells within 18 h upon stimulation. The patterns of CD69 expression and T helper-type 1 (Th1)-promoting cytokines production were similarly shown when human peripheral blood lymphocytes were stimulated with the other three major pathogens. Our results suggest that A. otitidis has sufficient immunogenic potential to modulate a host immune response, like the other three major middle ear pathogens, and also suggest that the immunogenicity of A. otitidis is very similar, at the early immune response, to that of the three major middle ear pathogens.

Enzymatic/biochemical analysis of Actinomyces with commercial test kits with an emphasis on newly described species.

In clinical microbiology laboratories, the identification of Actinomyces-like bacteria can be very laborious and problematic. In the present study, we focused on reactivity patterns of 4 commercial test kits, RapID ANA II, RapID 32A, RapID CB Plus, and BBL Crystal ANR ID, that could be used for rapid preliminary identification of Actinomyces isolates belonging to newly described Actinomyces and closely related species. Out of the 54 strains tested, 25 strains (46%) were correctly identified to the genus/group level by BBL Crystal ANR ID system, 16 strains (30%) by RapID 32 A, 11 strains (20%) by RapID CB Plus, and 7 strains (13%) by RapID ANA II. The main problems with these kits were due to occasional weak enzymatic and sugar fermentation reactions. In conclusion, chromogenic substrate sensitivity and specificity need to be enhanced in order to improve the reliability of the test results of these kits, and the present database updated in order to more precisely identify newly described Actinomyces and closely related species.

Nosocomial bloodstream infections due to viridans streptococci in haematological and non-haematological patients: species distribution and antimicrobial resistance.

OBJECTIVES: We studied the species distribution and antimicrobial susceptibility of viridans streptococci (VS) isolates causing nosocomial bloodstream infections (BSIs) in Finnish hospitals. PATIENTS AND METHODS: Patients with nosocomial BSIs due to VS were identified through a hospital-wide prospective laboratory-based surveillance in two university and two regional hospitals during September 1998-August 2001. Isolates of VS were sent to the reference laboratory for species confirmation and antimicrobial susceptibility testing. RESULTS: A total of 2038 nosocomial BSIs were identified; 108 (5%) of the BSIs were caused by VS. Of the VS BSIs, 66% were in patients with a haematological malignancy, 14% in patients with a solid tumour and 18% in patients who had undergone surgery preceding the infection. The most common species group identified was Streptococcus mitis (82%). High-level penicillin resistance (> or = 4 mg/L) and cefotaxime resistance (> or = 4mg/L) were present in 5% and 4% of isolates, respectively; both were detected only in haematological patients. However, in non-haematological patients, resistance to erythromycin (17%), and reduced susceptibility to levofloxacin (14%) and penicillin (19%) were common. CONCLUSIONS: The resistance problems in VS are not limited to haematological patients. These findings may have significant clinical implications in the choice of both empirical antibiotic and antimicrobial prophylaxis regimens.

Evaluation of four commercial test systems for identification of actinomyces and some closely related species.

We evaluated four commercially available kits for rapid identification of Actinomyces and related species. The kits identified correctly 26 to 65% of "classical" Actinomyces strains to the species level and 13 to 49% of newly described Actinomyces strains to the genus level, thus indicating relatively poor applicability and a need to update these kits.

Actinobacillus actinomycetemcomitans and Haemophilus aphrophilus in systemic and nonoral infections in Finland.

The oral cavity is the ecological niche for Actinobacillus actinomycetemcomitans and Haemophilus aphrophilus, but occasionally they cause severe nonoral infections. In this study we present 20 systemic or nonoral infections due to A. actinomycetemcomitans and H. aphrophilus, comprising all isolates of these species forwarded to and stored in Finnish reference laboratories during the years 1988-2000. The time from specimen collection to correct species identification was 9.3 days for A. actinomycetemcomitans and 10.7 days for H. aphrophilus. A. actinomycetemcomitans strains represented serotypes a, b, c, and d. Arbitrarily primed PCR distinguished four A. actinomycetemcomitans and six H. aphrophilus genotypes. Antimicrobial susceptibility testing with benzylpenicillin, amoxicillin, tetracycline, metronidazole, azithromycin, and trovafloxacin showed generally good activities against the present strains, and the susceptibility patterns closely resembled those of oral strains. The prolonged time to recover and identify A. actinomycetemcomitans and H. aphrophilus from systemic and nonoral infections may delay the correct diagnosis of the patient, but the good antimicrobial efficacies of antimicrobial agents against these pathogens give a good prognosis for the patients and advance the treatment of severe infections caused by these fastidious organisms of oral origin.

Incidence, treatment and outcome of peripartum sepsis.

BACKGROUND AND METHODS: Clinical and microbiological features of maternal sepsis in the peripartum period (7 days before to 7 days after delivery) were analyzed to determine possible risk factors, optimal treatment and outcome. In 43 483 deliveries during 1990-98, laboratory-confirmed bacteremia was found in 41 (5.1%) out of 798 clinically suspected septic infections. RESULTS: Preterm deliveries were associated with a crude 2.7-fold risk for peripartum sepsis as compared to term deliveries. Antepartum sepsis was associated with a crude 2.6-fold risk for cesarean section, while postpartum sepsis was 3.2 times more likely to occur after cesarean section than after vaginal delivery. A combination of cefuroxime and metronidazole was used in 80% (33/41) of all treatments. All mothers recovered well, and only one suffered from septic shock. In total, 42 bacterial strains, representing 18 different bacterial species, were isolated from the blood cultures; 37 strains (88%, 37/42) were aerobic and five (12%, 5/42) were anaerobic. The most common species were betahemolytic streptococci, Escherichia coli and Staphylococcus aureus. Most microbes (81%, 34/42) were found to be susceptible to first- or second-generation cephalosporins. CONCLUSION: Our analysis shows that peripartum sepsis is associated with preterm pregnancies and cesarean sections. Treatment of peripartum sepsis with second-generation cephalosporin is usually effective, and the outcome is good.

Invasive group B streptococcal infections in Finland: a population-based study.

We analyzed surveillance data on group B streptococcus (GBS) infection in Finland from 1995 to 2000 and reviewed neonatal cases of early-onset GBS infection in selected hospitals in 1999 to 2000. From 1995 to 2000, 853 cases were reported (annual incidence 2.2-3.0/100,000 population). We found 32-38 neonatal cases of early-onset GBS disease per year (annual incidence 0.6-0.7/1,000 live births). In five hospitals, 35% of 26 neonatal cases of early-onset GBS infection had at least one risk factor: prolonged rupture of membranes, preterm delivery, or intrapartum fever. Five of eight mothers screened for GBS were colonized. In one case, disease developed despite intrapartum chemoprophylaxis. Although the incidence of early-onset GBS disease in Finland is relatively low, some geographic variation exists, and current prevention practices are suboptimal. Establishing national guidelines to prevent perinatal GBS is likely to reduce the incidence of the disease.