Autophagy vs. Group A Streptococcus

We have identified several mammalian protein components of the autophagy pathway. By using them as powerful tools to examine the functional significance of this degradation pathway, we recently showed that autophagy efficiently kills a pathogenic bacterium, Group A Streptococcus, after it invades host cells. However, the autophagosomes induced by these bacteria have features distinct from those of the canonical pathway.

Brain abscess associated with cerebral amyloid angiopathy and hemorrhage

PURPOSE

We want to report an extremely rare condition, brain abscess associated with cerebral amylid angiopathy and hemorrhage.

CASE REPORT

We report on a 64-year-old woman who presented initially with moderate fever and headache. She was initially misdiagnosed with a bleeding tumor or arteriovenous malformation rupture and treated without antibiotic therapy. The mass was surgically drained due to neurological deterioration on day 14 after admission. Streptococcus virdians was isolated from the pus culture. The pathology evaluation showed cerebral amyloid angiopathy. She received intravenous antibiotic therapy for 4 weeks. She was eventually discharged home with left quadrantanopia.

CONCLUSION

This case reminds us early recognition of brain abscess formation at the site of intracerebral hemorrhage is very important for prompt and appropriate treatment to improve the overall prognosis.

Cloning of a crustin-like, single whey-acidic-domain, antibacterial peptide from the haemocytes of the European lobster, Homarus gammarus, and its response to infection with bacteria

Degenerate PCR was used to isolate a 221-base pair nucleotide sequence of a new crustin-like antibacterial peptide from the haemocytes of the European lobster, Homarus gammarus. Rapid amplification of cDNA ends was used to extend the sequence to determine the complete open reading frame and un-translated regions. The inferred amino acid sequence of this peptide was found to be similar to crustin-like peptides isolated for several species of shrimp as well as the shore crab, Carcinus maenas. The sequence also contains a single-whey-acidic protein (WAP) domain, similar to novel antibacterial single-whey-acidic domain (SWD) peptides that have been recently described in the tiger shrimp, Penaeus monodon, and the Pacific white shrimp, Litopenaeus vannamei. Real-time PCR was used to analyse the expression of the gene coding for this peptide. The gene is up regulated after inoculation with the Gram-positive lobster pathogen Aerococcus viridans var. homari but down regulated after inoculation with the Gram-negative bacteria Listonella anguillarum. Phylogenetic analysis of this new peptide shows that it is most related to other antimicrobial crustin peptides and that the crustins are only distantly related to the antibacterial SWD peptides recently described.

Evaluation of pathogenic indicator bacteria in structural best management practices

This study evaluated the bacteria removal efficiency, re-suspension and survivability within two structural Best Management Practices (BMPs) called Vortechs installed at two different sites in Providence, Rhode Island. Twelve rain storms were sampled during years 2004 and 2005. Five pathogenic indicator bacteria, E. coli, enterococci, fecal streptococci, total coliform, fecal coliform, were analyzed. Results showed that Vortechs was effective in partial removal of pathogenic indicator bacteria (PIB, 39-86%), however, the PIB concentrations after Vortechs treatment were still significantly high, which could limit the use of receiving waters and raise concerns for public health. The indicator bacteria concentrations in the sump water were 1.2-2.6 times higher than that contributed by the incoming stormwater. This result suggests some bacteria were re-suspended from the sediments within the Vortechs. Low bacterial survivability of bacteria was found in the sump water at both sampling sites; however, much lower bacteria concentrations were detected at Site 2, suggesting a higher bacteria contamination from highway runoff.

Prospective study of the long term change of the oral flora after radiation therapy

OBJECTIVES

The aim of this prospective study was to evaluate the long term change in oral pathogens following radiation therapy.

METHODS

Twenty-two patients with planned radiation therapy (>30 Gy) of head and neck squamous cell carcinoma were included. Before radiation therapy, after 3, 6, and 12 months samples from the deepest periodontal pocket were drawn. Five major periodontal pathogens were studied using DNA probes (Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, Bacteriodes forsythus, Treponema denticola). Stimulated saliva was sampled for the microbiologic study of caries pathogens (streptococci and lactobacilli). Plaque index and decayed, missing, filled tooth surfaces (DMF-S) were recorded.

RESULTS

A normalisation of the caries bacteria is not found correlating to a significant increase in the number of affected teeth (DMF-S) from 80.7 to 88.5 after 12 months. The plaque index remained unchanged. The incidence of periodontal pathogens did not significantly change during the follow up.

CONCLUSION

In contrast to radiation caries there seems to be no microbiological evidence for "radiation periodontitis". Despite of the intensive oral hygiene no reduction of the high number of caries pathogens is found, which leads to a high risk of tooth decay even 12 months after radiation.

[Interaction of bacteria and red blood cells]

The interaction of staphylococci, streptococci, meningococci, enterobacteria, leptospires and other microorganisms with red blood cells is considered. Three forms of the interaction of bacteria and red blood cells are discussed: adhesion, the influence of secretory factors on red blood cells, the action of pathogenic bacteria on hemoglobin. The applied aspects of the interaction of bacteria and red blood cells in the human body are presented in accordance with the results of clinical and laboratory studies.

Studies on the virulence of Aerococcus viridans (var.) homari, the causative agent of gaffkemia, a fatal disease of homarid lobsters

Virulent and avirulent strains of Aerococcus viridans (var.) homari were used to extend previous studies to determine and confirm differences between the 2 types. Virulent strains possessed polysaccharide capsules and were not agglutinated by lobster hemolymph serum; avirulent strains did not have capsules, were agglutinated by the lobster hemolymph serum, and most did not grow well in lobster hemolymph serum. Growth of the avirulent strains in sterile lobster hemolymph serum induced the production of capsules (which reached a maximum after 5 to 7 d incubation), eliminated susceptibility of the strains to the lobster serum agglutinin, and restored their virulence against lobsters. The factor(s) in lobster hemolymph serum inducing the long-lasting phenotypic response of virulence was (were) heat labile.

Total knee arthroplasty infection due to Abiotrophia defectiva

The first documented case of knee alloarthroplasty infection due to Abiotrophia defectiva, formerly known as nutritionally variant streptococci (NVS) and Streptococcus defectivus, is presented. The microbiology of this bacterium is discussed and clinical features of previously reported cases of infections by NVS are reviewed briefly.

[Aerococcus urinae and urinary tract infection]

BACKGROUND

Bacteriological investigation of urine often shows the presence of alpha-haemolytic streptococci, but the clinical significance of this finding may be unclear. Among the alpha-haemolytic streptococci found in urine is Aerococcus urinae, which is pathogenic.

MATERIAL AND METHODS

We present a prospective study of the prevalence and antibiotic susceptibility of A urinae in urine samples sent to a microbiology laboratory in Norway.

RESULTS

Seven out of 27 alpha-haemolytic streptococcal isolates were A urinae. This represents 0.3% of all urine isolates from our laboratory. Appropriate methods for identification and resistance determination are described.

INTERPRETATION

Microbiological laboratories should include identification of A urinae in their diagnostic repertoire. Recommended treatment against A urinae is ampicillin or nitrofurantoin.

Estimated prevalence of Aerococcus viridans and Anophryoides haemophila in American lobsters Homarus americanus freshly captured in the waters of Prince Edward Island, Canada

The Canadian lobster industry holds lobsters Homarus americanus in captivity for various periods to supply markets with live product year-round. Mortality during holding results in considerable losses, estimated at 10 to 15 % yr(-1) by the industry. This study examined the prevalence of Anophryoides haemophila and Aerococcus viridans, causative agents of 'bumper car' disease and gaffkemia, respectively, in lobsters freshly captured in the waters of Prince Edward Island during the spring and fall fishing seasons of 1997. A total of 116 lobsters were sampled in the spring, and 138 in the fall. A. haemophila was not detected in the spring, while the prevalence was 0.72 % in the fall with a 95% confidence interval (CI) of 0.02 to 3.97% and an overall prevalence of 0.39% (95% CI: 0.01 to 2.17%). The prevalence of A. viridans was estimated at 6.9% (95% CI: 3.0 to 13.14%) in the spring, 5.8% in the fall (95% CI: 2.54 to 11.10%), and 6.30% overall (95% CI: 3.64 to 10.03%). Because of the reduced interest in food of diseased lobsters, and compromised metabolism in the case of gaffkemia, these prevalence estimates are likely underestimates of the true prevalence of gaffkemia and 'bumper car' disease in the wild populations of lobster around Prince Edward Island.

Lipid peroxidation, osmotic fragility and antioxidant status in children with acute post-streptococcal glomerulonephritis

Plasma and erythrocyte samples from acute post-streptococcal glomerulonephritis (APSGN) children and control children were enrolled in this study. Lipid peroxidation (LPO), measured in terms of thiobarbituric acid-reactive substances (TBARS) was found to be significantly increased in plasma and RBCs of APSGN children (P<0.05) than in control children. Osmotic fragility of erythrocytes was examined. RBCs of APSGN patients were found to be osmotically more sensitive towards hypotonic saline (50% hemolysis at 7 g/l saline) when compared to control RBCs (50% hemolysis at 4 g/l saline). The activities of antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione S-transferase (GST) were significantly lowered (P<0.05) in APSGN RBCs when compared to control RBCs. Plasma ascorbic acid, reduced glutathione (GSH), RBC ascorbic acid, GSH and RBC total sulphydryl content (TSH) were significantly depleted in APSGN children relative to controls. The susceptibility of RBCs of APSGN children to lipid peroxidation was confirmed in this study.

Urinary tract infections in adults with diabetes

Urinary tract (UTI) is a major disease burden for many patients with diabetes. Asymptomatic bacteriuria is several-fold more common among women and acute plyelonephritis is five to ten times more common in both sexes. The complications of pyelonephritis are also more common in patients with diabetes. These complications include acute papillary necrosis, emphysematous pyelonephritis, and bacteremia with metastatic localization to other sites. The management of urinary infection in patients with diabetes is essentially the same as patients without diabetes. Most infections should be managed as uncomplicated except when they occur in a milieu with obstruction or other factors that merit a diagnosis of complicated UTI. Strategies to prevent these infections and reduce morbidity should be a priority for research.

[Some features of tonsillar microflora and microbial interaction (in normal and pathological states)]

The description of a new method for the determination of interaction between bacterial strains isolated from the mucous membrane of tonsils of healthy children and patients with chronic tonsillitis. In the analysis of mutual influence of symbionts on the hemolytic, lecitovitellase, lysozyme and antilysozyme activity of microbes isolated from healthy children no changes in the expression of these pathogenicity and persistence factors have been detected in the overwhelming majority of cases (70.8-89.9%). In the microflora of sick children interactions were synergic with respect to pathogenicity factors in 35.2-46.7% of cases and antagonistic in 18.7-31.3% of cases.

Heterologous inducible expression of Enterococcus faecalis pCF10 aggregation substance asc10 in Lactococcus lactis and Streptococcus gordonii contributes to cell hydrophobicity and adhesion to fibrin

Aggregation substance proteins encoded by the sex pheromone plasmid family of Enterococcus faecalis have been shown previously to contribute to the formation of a stable mating complex between donor and recipient cells and have been implicated in the virulence of this increasingly important nosocomial pathogen. In an effort to characterize the protein further, prgB, the gene encoding the aggregation substance Asc10 on pCF10, was cloned in a vector containing the nisin-inducible nisA promoter and its two-component regulatory system. Expression of aggregation substance after nisin addition to cultures of E. faecalis and the heterologous bacteria Lactococcus lactis and Streptococcus gordonii was demonstrated. Electron microscopy revealed that Asc10 was presented on the cell surfaces of E. faecalis and L. lactis but not on that of S. gordonii. The protein was also found in the cell culture supernatants of all three species. Characterization of Asc10 on the cell surfaces of E. faecalis and L. lactis revealed a significant increase in cell surface hydrophobicity upon expression of the protein. Heterologous expression of Asc10 on L. lactis also allowed the recognition of its binding ligand (EBS) on the enterococcal cell surface, as indicated by increased transfer of a conjugative transposon. We also found that adhesion of Asc10-expressing bacterial cells to fibrin was elevated, consistent with a role for the protein in the pathogenesis of enterococcal endocarditis. The data demonstrate that Asc10 expressed under the control of the nisA promoter in heterologous species will be an useful tool in the detailed characterization of this important enterococcal conjugation protein and virulence factor.

Endocardiac infectivity and binding to extracellular matrix proteins of oral Abiotrophia species

Microorganisms of the genus Abiotrophia, formerly known as nutritionally variant streptococci, are members of the oral flora and often isolated from patients with endocarditis, but pathogenicity of oral Abiotrophia species has not been examined yet. In this study, 17 strains isolated from healthy human oral cavities and 7 reference strains (all derived from patients with endocarditis) of Abiotrophia spp. were tested for their abilities to cause infections in damaged heart tissues in catheterized rats and to adhere to extracellular matrix proteins in vitro. The reference strains of A. defectiva and A. adiacens showed high infectivities in the rats. Four oral isolates of these two species showed similarly high infectivities and three had moderate infectivities. Most of 10 oral strains of A. para-adiacens and A. elegans were found to be generally less infective. The highly infective A. adiacens strains showed markedly high fibronectin-binding capacity, suggesting a possible relationship between the fibronectin-binding capacity and damaged heart tissue infectivity of the Abiotrophia species. A. defectiva strains which were also highly infective had moderate levels of binding to fibronectin and other extracellular matrix proteins. Most of A. para-adiacens and A. elegans strains showed low or negligible binding capacities to any extracellular matrix proteins tested.

[Aerococcus urinae. A newcomer among pathogenic bacteria in clinical and microbiological practice]

A decade ago we discovered a hitherto unrecognized Aerococcus-like organism (ALO) in urine specimens from patients with urinary tract infection. Further microbiological and clinical investigations enabled us to classify it as a human pathogen also causing urogenic septicaemia and endocarditis, the latter often with lethal outcome. The organism is now designated Aerococcus urinae.

Three cases of serious infection caused by Aerococcus urinae

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.

The Streptococcus milleri group as a cause of pulmonary infections

Streptococci that colonize the mouth and upper respiratory tract tend to be considered harmless commensals. In 45 cases of acute pneumonia and/or pulmonary abscess and 25 cases of thoracic empyema, the predominant species recovered were anaerobic bacteria and the Streptococcus milleri group, which encompasses the oral species Streptococcus anginosus, Streptococcus constellatus, and Streptococcus intermedius. The isolation of most S. milleri organisms along with oral anaerobes indicated synergy between these groups. Studies in a mouse model of pneumonia demonstrated this synergy; mortality was higher, histopathologic abnormalities were more marked (reflecting acute pneumonia followed by pulmonary abscess or empyema), and viable bacteria were more numerous in the lungs of mice with mixed infections caused by the S. milleri group and anaerobes than in the lungs of those with monomicrobial infection. In vitro studies elucidated a possible mechanism of this synergistic effect: anaerobes may enhance the growth of the S. milleri group and/or inhibit the bactericidal activity of the host. We conclude that the S. milleri group is more important in pulmonary infections than has previously been recognized.

Microaerophilic streptococci as a significant pathogen: a twelve-year review

One hundred twenty three microaerophilic streptococci (MS) were isolated from 4,603 specimens submitted for the identification of anaerobic bacteria over the course of 12 years. The MS included 16 Streptococcus constellatus, 43 Streptococcus intermedius and 21 Gemella morbillorum. A total of 81 MS isolates (66%) identified from 75 patients were considered to cause infection. Predisposing or underlying conditions were noted in 48 (64%) patients. The most common conditions were previous surgery (15 instances), trauma (10), diabetes (9), immunodeficiency (6), malignancy, and prosthetic device (5 each). MS were the only bacterial isolates in 23 instances. Mixed infection was encountered in 52 (69%) patients, where the number of isolates varied between two and five (average 2.7). The organisms most commonly isolated with MS were anaerobic cocci, Bacteroides sp. and Enterobacteriaceae; their recovery varied at different sites. Significant infections caused by MS were associated with abscess (29 instances), sinuses (7), obstetrical and gynecological (OBG), chest and wounds (6 each), abdominal (5), and biliary infection (4). Antimicrobial therapy as administered to 71 patients; for 43 patients, in conjunction with surgical drainage or correction. Surgical drainage alone was performed in three patients. Four patients (5%) died. These data illustrate that MS can occasionally be associated with serious infection.

Interactions between bacteria and influenza A virus in the development of influenza pneumonia

Different proteases from various microorganisms present in the respiratory tract were capable of enhancing influenza virus infectivity and pathogenicity in mice by proteolytic activation of hemagglutinin (HA). Aerococcus viridans, isolated from a patient with pneumonia, secreted a protease that could activate HA directly, similarly to some Staphylococcus aureus strains. The protease of Pseudomonas aeruginosa could not activate HA directly, but combined application of P. aeruginosa protease and virus into mice enhanced virus titers and pathogenicity. Generation of trypsin-like activity in bronchoalveolar lavage fluids resulting from this combination treatment may be responsible for HA activation. A similar indirect effect on HA activation was induced by streptokinase and staphylokinase, which are known to generate plasmin by plasminogen activation. It was concluded that plasminogen-activating streptococci and staphylococci facilitate viral replication and pathogenicity of plasmin-sensitive influenza virus strains by amplification of the plasminogen/plasmin system.

[The adhesive and colonizing properties of Aerococcus viridans]

On the basis of experiments carried out in the course of this study the conclusion can be made that one of the mechanisms of the preventive effect of aerococci, the representatives of the indigenous microflora of the gastrointestinal tract, lies in their capacity for adhesion to and colonization of the mucous membrane, this enhancing the resistance of the enteric tract to infections. These properties of anterococci substantiate good prospects of using M-bacterin (live lyophilized aerococcal culture) for the control of enteric infections and dysbacteriosis.

Aerococcus-like organism, a newly recognized potential urinary tract pathogen

During the last 10 to 15 years, Aerococcus-like organisms have been isolated from urinary tract specimens from hospitalized patients at Bispebjerg Hospital, Copenhagen, Denmark, with signs of urinary tract infection, and a single strain has been deposited at the National Collection of Type Cultures (NCTC 12142). An additional 63 isolates from the urine specimens of as many patients with suspected urinary tract infection have been identified from seven departments of clinical microbiology in Denmark. Clinical information indicates that this organism may be involved in urinary tract infection. These strains and ten previously collected strains, two of which were from blood cultures, were characterized phenotypically. By comparing the results with data on other gram-positive, catalase-negative cocci or coccobacillary organisms, the identified organisms seem to represent a separate taxon.

Aerococcus-like organism--an unnoticed urinary tract pathogen

Aerococci are only occasionally isolated from urinary tract specimens. A 4-month' survey revealed 29 patients suspected of urinary tract infection (UTI), from whom an Aerococcus-like organism (ALO) was isolated in significant numbers from urinary tract specimens and singly in 11 cases. Approximately 0.8% of all urinary tract specimens examined during the period yielded growth of ALO. The median age of patients was 75 years. Half of the patients were found to have conditions predisposing to UTI. 9 of 11 patients without indwelling catheter, having ALO isolated in pure culture from the urine, showed one or more typical signs of UTI (fever, dysuria and/or pollakisuria and pyuria). A phenotypic comparison was made between 29 strains of ALO and 6 related organisms, including Aerococcus viridans, Streptococcus faecium, Streptococcus sanguis, Streptococcus bovis, Streptococcus Group Q and Streptococcus Group R. ALO and A. viridans showed many similarities, but, owing to characteristic differences with regard to colony morphology, biochemical reactions and antibiotic susceptibility pattern, the strains were easily separated.

Serological grouping of virulent and avirulent strains of the lobster pathogen Aerococcus viridans

Virulent strains of Aerococcus viridans (formerly Gaffkya homari) are the aetiologic agents of gaffkemia, a septicaemic disease of the American lobster (Homarus americanus). The virulent and avirulent forms of this bacterium, previously thought to be taxonomically indistinguishable, have been differentiated by serological studies. Antisera were produced in rabbits using autoclaved bacteria as antigens. Reactions were measured by agglutination tests using microtitre techniques and an antigenic scheme was determined. Specific antisera were prepared by absorption and used to determine antigens of strains of A. viridans and other Gram-positive cocci. In general, only virulent strains of A. viridans have antigen b. Both virulent and avirulent strains possess other antigens also detected in strains of the genus Staphylococcus.

Effects of Gaffkya homari on glucose, total carbohydrates, and lactic acid of the hemolymph of the lobster (Homarus americanus)

The lobster pathogen, Gaffkya homari, in vitro and in vivo caused the virtual disappearance of glucose and lactic acid from the hemolymph of the lobster, Homarus americanus. In vitro results suggested that almost half of the non-glucose components of the hemolymph could be used by G. homari.

Association of toxic capsule and cell wall mucopeptide with virulence in Gaffkya tetragena

Nine strains of organisms morphologically and physiologically identified as Gaffkya tetragena were obtained from various sources to study their pathogenicity. Initial virulence analysis of all strains by mouse intraperitoneal injection of viable cells revealed that only three strains, recently isolated from and associated with respiratory infections in hospitalized patients, caused death of mice within 48 hr. The ld(50) for these virulent, encapsulated strains was 1 x 10(7) to 6 x 10(7) viable organisms. To associate virulence with a toxic component, the following fractions were purified from all strains: capsular material, cell walls, mucopeptide preparations from cell walls and whole cells, grouplike material, cytoplasmic material, and culture filtrate with and without added reducing agent. Rabbit and mouse dermal toxicity testing of these fractions revealed that the capsular material, cell walls, and mucopeptide preparations of the virulent strains were toxic. None of the nonvirulent strains contained toxic components, with the exception of one strain which yielded capsular material equal in toxicity to that of the virulent strains. The capsular material induced a soft pustular lesion persisting for approximately 22 days. Cell walls and mucopeptide preparations produced a hard nodular lesion, identical to that produced by autoclaved whole cells, that persisted for 25 to 30 days. One strain may represent a virulence intermediate between the virulent and nonvirulent strains, since it contains toxic capsular material but nontoxic cell wall mucopeptide. The results indicate that the virulence of this organism is associated with toxic capsular material and cell wall mucopeptide.