Anginosus Group Research Articles

A Reference Broth Microdilution Method for Dalbavancin In Vitro Susceptibility Testing of Bacteria that Grow Aerobically.

Antimicrobial susceptibility testing (AST) is performed to assess the in vitro activity of antimicrobial agents against various bacteria. The AST results, which are expressed as minimum inhibitory concentrations (MICs) are used in research for antimicrobial development and monitoring of resistance development and in the clinical setting for antimicrobial therapy guidance. Dalbavancin is a semi-synthetic lipoglycopeptide antimicrobial agent that was approved in May 2014 by the Food and Drug Administration (FDA) for the treatment of acute bacterial skin and skin structure infections caused by Gram-positive organisms. The advantage of dalbavancin over current anti-staphylococcal therapies is its long half-life, which allows for once-weekly dosing. Dalbavancin has activity against Staphylococcus aureus (including both methicillin-susceptible S. aureus [MSSA] and methicillin-resistant S. aureus [MRSA]), coagulase-negative staphylococci, Streptococcus pneumoniae, Streptococcus anginosus group, β-hemolytic streptococci and vancomycin susceptible enterococci. Similar to other recent lipoglycopeptide agents, optimization of CLSI and ISO broth susceptibility test methods includes the use of dimethyl sulfoxide (DMSO) as a solvent when preparing stock solutions and polysorbate 80 (P80) to alleviate adherence of the agent to plastic. Prior to the clinical studies and during the initial development of dalbavancin, susceptibility studies were not performed with the use of P-80 and MIC results tended to be 2-4 fold higher and similarly higher MIC results were obtained with the agar dilution susceptibility method. Dalbavancin was first included in CLSI broth microdilution methodology tables in 2005 and amended in 2006 to clarify use of DMSO and P-80. The broth microdilution (BMD) procedure shown here is specific to dalbavancin and is in accordance with the CLSI and ISO methods, with step-by-step detail and focus on the critical steps added for clarity.

A Reference Broth Microdilution Method for Dalbavancin <em>In Vitro</em> Susceptibility Testing of Bacteria that Grow Aerobically

Antimicrobial susceptibility testing (AST) is performed to assess the in vitro activity of antimicrobial agents against various bacteria. The AST results, which are expressed as minimum inhibitory concentrations (MICs) are used in research for antimicrobial development and monitoring of resistance development and in the clinical setting for antimicrobial therapy guidance. Dalbavancin is a semi-synthetic lipoglycopeptide antimicrobial agent that was approved in May 2014 by the Food and Drug Administration (FDA) for the treatment of acute bacterial skin and skin structure infections caused by Gram-positive organisms. The advantage of dalbavancin over current anti-staphylococcal therapies is its long half-life, which allows for once-weekly dosing. Dalbavancin has activity against Staphylococcus aureus (including both methicillin-susceptible S. aureus [MSSA] and methicillin-resistant S. aureus [MRSA]), coagulase-negative staphylococci, Streptococcus pneumoniae, Streptococcus anginosus group, β-hemolytic streptococci and vancomycin susceptible enterococci. Similar to other recent lipoglycopeptide agents, optimization of CLSI and ISO broth susceptibility test methods includes the use of dimethyl sulfoxide (DMSO) as a solvent when preparing stock solutions and polysorbate 80 (P80) to alleviate adherence of the agent to plastic. Prior to the clinical studies and during the initial development of dalbavancin, susceptibility studies were not performed with the use of P-80 and MIC results tended to be 2-4 fold higher and similarly higher MIC results were obtained with the agar dilution susceptibility method. Dalbavancin was first included in CLSI broth microdilution methodology tables in 2005 and amended in 2006 to clarify use of DMSO and P-80. The broth microdilution (BMD) procedure shown here is specific to dalbavancin and is in accordance with the CLSI and ISO methods, with step-by-step detail and focus on the critical steps added for clarity.

Telavancin: mechanisms of action, in vitro activity, and mechanisms of resistance.

Telavancin is a semisynthetic lipoglycopeptide derivative of vancomycin. Telavancin has a dual mechanism of antibacterial action, disrupting peptidoglycan synthesis and cell membrane function. In 2014, the Clinical and Laboratory Standards Institute (CLSI) revised the antimicrobial susceptibility testing method for telavancin, resulting in minimum inhibitory concentration (MIC) determinations that are more accurate and reproducible and demonstrate greater in vitro potency than shown with the previous testing method. The CLSI testing method changes coincided with revised telavancin MIC interpretive break point criteria for susceptibility approved by the US Food and Drug Administration for Staphylococcus aureus (≤0.12 µg/mL), Streptococcus pyogenes (≤0.12 µg/mL), Streptococcus agalactiae (≤0.12 µg/mL), Streptococcus anginosus group (≤0.06 µg/mL), and Enterococcus faecalis (vancomycin susceptible, ≤0.25 µg/mL). Telavancin is equally potent against methicillin-susceptible S. aureus (MSSA) and methicillin-resistant S. aureus (MRSA). It demonstrates activity against isolates of heterogeneous vancomycin-intermediate S. aureus and vancomycin-intermediate S. aureus but is poorly active against vancomycin-resistant S. aureus. It also demonstrates potent activity against Staphylococcus epidermidis and Streptococcus spp. (MIC90 ≤0.03 µg/mL). Thus far, it has not been possible to select for high-level telavancin resistance in the laboratory using serially passaged clinical isolates of MRSA and MSSA.

Pediatric sinogenic epidural and subdural empyema: The role of endoscopic sinus surgery

AimTo analyze the indications and outcomes of open neurosurgical approaches (ONA) and endoscopic transnasal approaches (ETA) in the surgical management of pediatric sinogenic subdural and epidural empyema. Material and methodsRetrospective single-center study design within a tertiary care referral center setting. Children less than 18 years of age consecutively operated on between January 2012 and February 2014 for drainage of a sinogenic subdural empyema (SE) or epidural (EE) empyema were included. Main outcome measures: success of first surgical procedure, persistent symptoms and sequelae at the end of the follow-up period. ResultsNine SE (53%) and 8 EE (47%) were observed. Neurological symptoms, especially seizures, were more frequent in the SE group. Perioperative pus samples were positive in 67% of the SE group and in 75% of the EE group. The most frequently isolated bacteria belonged to the Streptococcus anginosus group. CT or MR imaging showed that most empyema probably originated from the frontal sinus. However, two cases resulted from an ethmoiditis and one case from a Pott's puffy tumor, without any direct contact with the paranasal sinus. In cases of SE, the most effective surgical technique was ONA with craniotomy. Associated endoscopic sinus drainage was useful for the purpose of bacteriological diagnosis. In cases of EE, effectiveness was noted in both ONA and ETA techniques. In two cases of EE, the ETA procedure encompassed direct drainage of the empyema through the posterior wall of the frontal sinus (Draf III approach). The number of patients successfully treated after a single surgical procedure was higher in the EE group (p=0.05). Regarding outcomes, no mortalities were observed. Persistent disorders at the end of the follow-up period, especially headaches, cognitive, concentration or schooling problems, tended to be more frequent in the SE group than in the EE group (67% vs 29%), and were more commonly observed in cases requiring several surgical procedures (75% vs 12.5%) (p=0.05). DiscussionEndoscopic sinus surgery plays a critical role in the surgical management of pediatric sinogenic SE and EE. In cases of small volume EE, the endoscopic approach associated with antibiotherapy may be sufficient to treat the infectious process.

Liver abscess and respiratory disease caused by anginosus group streptococci

Anginosus group streptococci (previously known as Streptococcus milleri group) comprise three subspecies known to cause endogenous pyogenic infections. The majority of cases reported are in adults. We report a liver abscess occurring in a 3-year-old child without known preceding factors. He presented with clinical signs and X-ray findings compatible with a lower respiratory tract infection and was treated with oral amoxicillin. A blood culture grew Streptococcus constellatus and an abdominal ultra sound scan revealed a liver abscess confirmed by computerized tomography scan. Conservative management with a prolonged course of antibiotics led to complete resolution. Anginosus group streptococci can cause liver abscesses in healthy children and the presence of bacteremia due to this group of organisms should prompt investigation for occult abscesses.

Viridians Group Streptococci in Patients Undergoing Tooth Extraction

The aerobic microflora of the oral cavity consists of viridians group of streptococci (VGS). The present study was carried out with an objective to evaluate the prevalence of VGS in patients undergoing tooth extraction and to study their antibiotic susceptibility pattern. Samples of subgingival dental plaques for microbiological studies were collected from 80 patients undergoing tooth extraction. The isolated streptococci were identified along with their antibacterial susceptibilities by automated Vitek 2 (bioMerieux) system in accordance with CLSI standards. A total of 260 VGS strains belonging to 05 phenotypic groups, namely mutans, salivarius, anginosus, sanguinus and mitis groups; along with few strains of Granulicatella like G. adiacens and G. elegans. Altogether a total of 15 species were isolated from the subgingival plaque of 80 patients undergoing tooth extraction. Among the 15 antibiotics tested, highest resistance was observed to lincosamides (36.2%) followed by macrolides (29.7%), tetracyclines (17.7%), cephems (15.1%), fluoroquinolones (14.4%), oxazolidinones (13.5%), streptogramins (12.7 %) and penicillins (7.9%). However, all the 260 VGS strains were found susceptible to vancomycin and linezolid. In the subgingival plaque of patients undergoing tooth extraction, approximately 70% of streptococci belonged to three VGS groups, i.e. mitis, sanguinis and mutans groups. Streptococci of salivarus and anginosus groups were isolated sporadically (5%). Highest resistance was observed to lincosamides and macrolides (29.7%). Multiple antibiotic resistance was observed in mitis and salivarius group.

MLVF analysis of anginosus (milleri) group streptococci

We developed a new method of typing for anginosus group streptococci (SAG). It is the first SAG-dedicated, PCR-based method, which allows to determine the relationship between strains. The method is based on the detection of tandem repeats among 9 genomic loci and is classified as multilocus variable number tandem repeats fingerprint (MLVF) type of analysis. Using the described method, it is possible to detect over half million MLVF patterns, which correlate with pulsed-field gel electrophoresis profiles. The other advantage of the method is relatively short time from “cell to data”, low costs, and easy application for epidemiological and evolutionary studies.

Direct molecular versus culture-based assessment of Gram-positive cocci in biopsies of patients with major abscesses and diabetic foot infections.

Major abscesses and diabetic foot infections (DFIs) are predominant subtypes of complicated skin and skin structure infections (cSSSIs), and are mainly caused by Staphylococcus aureus and β-hemolytic streptococci. This study evaluates the potential benefit of direct pathogen-specific real-time polymerase chain reaction (PCR) assays in the identification of causative organisms of cSSSIs. One-hundred and fifty major abscess and 128 DFI biopsy samples were collected and microbial DNA was extracted by using the Universal Microbe Detection kit for tissue samples. Pathogen-specific PCRs were developed for S. aureus and its virulence factor Panton–Valentine leukocidin (PVL), Streptococcus pyogenes, S. agalactiae, S. dysgalactiae, and the S. anginosus group. Identification by pathogen-specific PCRs was compared to routine culture and both methods were considered as the gold standard for determination of the sensitivity and specificity of each assay. Direct real-time PCR assays of biopsy samples resulted in a 34 % higher detection of S. aureus, 37 % higher detection of S. pyogenes, 18 % higher detection of S. agalactiae, 4 % higher detection of S. dysgalactiae subspecies equisimilis, and 7 % higher detection of the S. anginosus group, compared to routine bacterial culture. The presence of PVL was mainly confined to S. aureus isolated from major abscess but not DFI biopsy samples. In conclusion, our pathogen-specific real-time PCR assays had a higher yield than culture methods and could be an additional method for the detection of relevant causative pathogens in biopsies.

Species-specific difference in antimicrobial susceptibility among viridans group streptococci.

BackgroundViridans group streptococci (VGS) are both commensal microbes and potential pathogens. Increasing resistance to penicillin in VGS is an ongoing issue in the clinical environment. We investigated the difference in susceptibility and resistance to penicillin among various VGS species.MethodsIn total 1,448 VGS isolated from various clinical specimens were analyzed over a two-yr period. Identification and antimicrobial susceptibility test was performed by the automated VITEK 2 system (bioMerieux, France) or the MicroScan MICroSTREP system (Siemens, Germany).ResultsAmong the 1,448 isolates, 412 were isolated from blood (28.4%). Streptococcus mitis group was the most frequently isolated (589 isolates, 40.7%), followed by the S. anginosus group (290 isolates, 20.0%), S. sanguinis group (179 isolates, 12.4%) and S. salivarius group (57 isolates, 3.9%). In total, 314 isolates could not be identified up to the species level. The overall non-susceptibility to penicillin was observed to be 40.0% (resistant, 11.2% and intermediately resistant, 28.8%) with uneven distribution among groups; 40.2% in S. sanguinis group (resistant, 5.0% and intermediately resistant, 35.2%), 60.3% in S. mitis group (resistant, 20.9% and intermediately resistant, 39.4%), 78.9% in S. salivarius group (resistant, 8.8% and intermediately resistant, 70.1%), and 6.2% in S. anginosus group (resistant, 1.7% and intermediately resistant, 4.5%).ConclusionsAntimicrobial resistance patterns towards penicillin show differences among various VGS; this should be considered while devising an effective antimicrobial treatment against VGS.

Surrogate analysis of vancomycin to predict susceptible categorization of dalbavancin

Dalbavancin (DAL) represents a recently approved addition for the treatment of acute bacterial skin and skin structure infections (ABSSSIs). Newly released antimicrobial agents are rarely found on commercial susceptibility testing devices, and surrogate testing may be an option for clinical microbiology laboratories. A total of 33,688 Staphylococcus aureus, 2800 viridans group streptococci (VGS), and 5722 β-hemolytic streptococci (BHS) were included in this cross-susceptibility (DAL versus vancomycin [VAN]) analysis as well as 4576 coagulase-negative staphylococci and 6515 enterococci (nonindicated species groups). Isolates were collected as part of the SENTRY Antimicrobial Surveillance Program for the United States (USA) and Europe (2011–2013). Susceptibility testing followed CLSI (M07-A9 and M100-S24) methods. USA Food and Drug Administration (DAL) and CLSI (VAN) breakpoint criteria were used for correlations between DAL and VAN susceptibility results. A categorical agreement (CA; susceptible) rate of 99.9% was observed between DAL and VAN when testing S. aureus. Only 48 (0.14%) very major (false-susceptible) errors were noted against VAN-susceptible isolates that displayed a DAL-nonsusceptible (MIC, 0.25 or 0.5μg/mL) phenotype. When susceptible MIC correlations were analyzed against indicated BHS species (Streptococcus agalactiae and Streptococcus pyogenes), an overall CA rate of 97.7–100.0% was obtained. Complete (100.0%) CA was documented for S. pyogenes, as well as against all VGS isolates, including the indicated Streptococcus anginosus group (758 strains). In conclusion, high susceptible CA rates between DAL and VAN were observed when testing a contemporary collection of indicated clinical isolates found in ABSSSI. VAN-susceptible isolates can be inferred to be inhibited by DAL (97.7–100.0%) at the regulatory agency–approved susceptible interpretive breakpoint of ≤0.12μg/mL.

Streptococcus constellatus Causing Septic Thrombophlebitis of the Right Ovarian Vein with Extension into the Inferior Vena Cava.

Introduction. Streptococcus constellatus collectively with Streptococcus anginosus and Streptococcus intermedius constitute the Streptococcus anginosus (formerly Streptococcus milleri) group. Though they are commonly associated with abscesses, bacteremia with subsequent septic thrombophlebitis is extremely rare, and resulting mortality is infrequent. Case Presentation. We report a case of a previously healthy 60-year-old African American female who presented with Streptococcus constellatus bacteremia associated with septic thrombophlebitis to the right ovarian vein extending into the inferior vena cava. She was urgently treated with antibiotics and anticoagulation. Conclusion. Septic thrombophlebitis has a clinical presentation that is often misleading. Therefore, a high clinical index of suspicion and the use of appropriate imaging modalities (computed tomography) are essential in recognizing and confirming this diagnosis. Prompt treatment is warranted. Surgical thrombectomies have been successfully replaced by a combination of antibiotics and anticoagulation therapy.

Streptococcus intermedius causing brain abscess in a child with acyanotic congenital heart defect

Streptococcus intermedius ( S. intermedius ) belongs to the Streptococcus anginosus group (SAG) along with Streptococcus anginosus ( S. anginosus ) and Streptococcus constellatus ( S. constellatus ) . Though all the members of SAG have a propensity to cause deep-seated abscesses at a wide range of sites, when it comes to brain abscesses, it is S. intermedius that is most often implicated. Paediatric population with congenital cyanotic heart disease are especially at risk for developing brain abscess. However, it is a rare occurrence in acyanotic congenital heart diseases. Here, we report a case of frontal brain abscess caused by S. intermedius in a child with a clinically silent atrial septal defect (ASD). However, an echocardiogram revealed a patent foramen ovale (PFO) accompanying the ASD. The child recovered, following burr hole aspiration and 21 days of antibiotic therapy. We report this case to highlight the importance of this pathogen in the aetiology of the brain abscess and due to the rarity of the case.

A Problem of Species Determination Using Housekeeping Genes in the Streptococcus anginosus Group

For identification of three species categorized in Streptococcus anginosus group (SAG), genotyping employing multiplex PCR for detection of species-specific genes has been widely used. We wondered whether possession of the specific genes correlated to differentiation of housekeeping genes, with an attempt to obtain more information on genetic background of clinical isolates of SAG strains and to evaluate reliability of the multiplex PCR. We therefore determined nucleotide sequences of some housekeeping genes of 52 SAG isolates from healthy volunteer to investigate whether the sequences phylogenetically corresponded to the identification by the multiplex PCR. The phylogenetic trees drawn with all of the sequences of 16S rRNA, sodA, groEL and rpoB were found to clearly correlate to species identified by the multiplex PCR. Interestingly, phylogenetic tree drawn only with single housekeeping gene often did not match with the species identified by the multiplex PCR. Our analysis implies even housekeeping genes can have their sequence varieties as independent manner from presence of species-specific genes in SAG strains, and the choice of housekeeping genes for the phylogenetic analyses may result in failure of the species identification.

Streptococcus anginosus group - brief characterization and its contribution to the brain abscess pathogenesis

Streptococcus anginosus group - brief characterization and its contribution to the brain abscess pathogenesis

Comparison of species identification of endocarditis associated viridans streptococci using rnpB genotyping and 2 MALDI-TOF systems

Streptococcus spp. are important causes of infective endocarditis but challenging in species identification. This study compared identification based on sequence determination of the rnpB gene with 2 systems of matrix-assisted laser desorption ionization–time of flight mass spectrometry, MALDI Biotyper (Bruker) and VITEK MS IVD (bioMérieux). Blood culture isolates of viridans streptococci from 63 patients with infective endocarditis were tested. The 3 methods showed full agreement for all 36 isolates identified in the Anginosus, Bovis, and Mutans groups or identified as Streptococcus cristatus, Streptococcus gordonii, or Streptococcus sanguinis. None of the methods could reliably identify the 23 isolates to the species level when designated as Streptococcus mitis, Streptococcus oralis, or Streptococcus tigurinus. In 7 isolates classified to the Mitis group, the rnpB sequences deviated strikingly from all reference sequences, and additional analysis of sodA and groEL genes indicated the occurrence of yet unidentified Streptococcus spp.

Dalbavancin, tedizolid phosphate, oritavancin diphosphate, and vedolizumab

Antibacterial agents Skin and skin structure infections are most often caused by Grampositive bacteria such as streptococci and staphylococci. The number of these infections that are caused by methicillin-resistant Staphylococcus aureus (MRSA) has rapidly increased in recent years in both the community and hospital settings. MRSA skin infections experienced in the community can usually be effectively treated with the oral use of trimethoprim-sulfamethoxazole, clindamycin, or doxycycline. Hospitalized patients with skin and skin structure infections (e.g., cellulitis, major abscess, wound infection) caused by MRSA usually require, at least initially, intravenous treatment with an antibiotic. Vancomycin continues to be highly effective for the treatment of most patients with these infections, but a number of options are available including linezolid (Zyvox), daptomycin (Cubicin), telavancin (Vibativ), and ceftaroline (Teflaro). Linezolid is available in formulations that may be administered intravenously or orally. In 2014, three new antibiotics— dalbavancin (Dalvance—Durata), tedizolid phosphate (Sivextro— Cubist), and oritavancin diphosphate (Orbactiv—The Medicines Company)—have been approved for the treatment of acute bacterial skin and skin structure infections (ABSSSI) caused by susceptible microorganisms. Based on the provisions of the Generating Antibiotic Incentives Now (GAIN) title of the Food and Drug Administration (FDA) Safety and Innovation Act, each of these antibiotics has been designated as a Qualified Infectious Disease Product (QIDP) because it is intended to treat a serious or life-threatening infection. Drugs receiving the QIDP designation are provided an expedited review of their application and qualify for an additional 5 years of marketing exclusivity. Dalbavancin, tedizolid, and oritavancin are considered on an individual basis in the following discussions. Dalbavancin (Dalvance—Durata) is a lipoglycopeptide that is a mixture of five closely related active homologs. It interferes with bacterial cell wall synthesis and exhibits a bactericidal action; and its properties are most similar to those of telavancin. Dalbavancin is administered by intravenous infusion and is specifically indicated for the treatment of adult patients with ABSSSI caused by susceptible isolates of the Gram-positive microorganisms Staphylococcus aureus (S. aureus) (including methicillin-susceptible and methicillin-resistant strains), Streptococcus pyogenes (S. pyogenes), Streptococcus agalactiae (S. agalactiae), and Streptococcus anginosus (S. anginosus) group (including S. anginosus, S. intermedius, and S. constellatus). It should only be used to treat infections that are proven or strongly suspected to be caused by susceptible bacteria. The results of in vitro studies suggest that dalbavancin is also active against vancomycin-susceptible Enterococcus faecium and Enterococcus faecalis (E. faecalis), as well as vancomycin-intermediate S. aureus. Dalbavancin, tedizolid phosphate, oritavancin diphosphate, and vedolizumab

Activity of oritavancin against Gram-positive clinical isolates responsible for documented skin and soft-tissue infections in European and US hospitals (2010-13).

To assess oritavancin activity in vitro against clinically relevant Gram-positive pathogens causing skin and soft-tissue infections (SSTIs) in European and US hospitals. 13 262 consecutive and unique isolates deemed to be responsible for SSTIs were included. Isolates originated from 36 and 27 institutions in Europe (Israel included) and the USA, respectively, between 2010 and 2013. Oritavancin (98.8% susceptible) showed modal MIC, MIC50 and MIC90 results of 0.03, 0.03 and 0.06 mg/L, respectively, for Staphylococcus aureus. CoNS from the USA (MIC50, 0.015 mg/L) demonstrated an MIC50 value of oritavancin slightly lower than those from Europe (MIC50, 0.03 mg/L). Overall, vancomycin-resistant (VanA-phenotype) Enterococcus faecalis had oritavancin MICs (MIC50/90, 0.25/0.5 mg/L) that were 16-fold higher than those obtained for vancomycin-susceptible isolates (MIC50/90, 0.015/0.03 mg/L; 99.2%-99.8% susceptible); nevertheless, oritavancin inhibited all VanA E. faecalis at ≤0.5 mg/L. Equivalent oritavancin MICs (MIC50/90, 0.004/0.008 mg/L) were noted for all VanB and vancomycin-susceptible Enterococcus faecium, while higher MICs (MIC50/90, 0.03/0.12 mg/L) were obtained for VanA strains. Oritavancin had low MICs against the overall populations of Streptococcus pyogenes (MIC50/90, 0.03/0.12 mg/L; 98.4%-98.6% susceptible), Streptococcus agalactiae (MIC50/90, 0.03/0.06 mg/L; 97.9%-98.0% susceptible) and the Streptococcus anginosus group (MIC50/90, 0.008/0.015 mg/L; 100.0% susceptible), with slightly higher MICs for Streptococcus dysgalactiae (MIC50/90, 0.06/0.25 mg/L; ≥98.3% susceptible). Oritavancin had potent activity in vitro against this contemporary collection of European and US isolates causing SSTIs. These results describe oritavancin activity against Gram-positive pathogens collected shortly prior to its regulatory approval in the USA.

Subperiosteal Abscess of the Orbit: Evolving Pathogens and the Therapeutic Protocol

Because of widespread antibiotic use, immunization against selective species, and the emergence of hypervirulent organisms, we sought to determine changes over time in the bacteriology of sinusitis-related subperiosteal abscess (SPA) of the orbit and their impact on patient outcomes under a uniform management protocol. Comparative case series. Patients≤18 years of age with sinusitis-related SPA treated from 2002 to 2012; comparable cohorts from earlier time frames. We analyzed culture results and outcomes in surgical cases, compared overall and age-specific results with those in a 1977 through 1992 patient series, and compared the proportion of patients<9 years old requiring surgery among 1988 through 1998, 1999 through 2008, and current cohorts. Patients requiring surgery; prevalence of pathogens; criteria prompting surgery; visual and systemic outcomes. Ninety-four patients met inclusion criteria: 53 (56%) recovered with medical therapy alone and 41 (44%) underwent surgical drainage. Compared with the 1977 through 1992 cohort, there was increased representation of Streptococcus anginosus group, S aureus, and group A β-streptococci. Methicillin-resistant S aureus (MRSA) accounted for 4 of 7 S aureus isolates. Of 94 patients, 74 (79%) were <9 years of age: 53 (72%) recovered without surgery and 21 (28%) underwent drainage. Comparable figures were 67.5% versus 32.5% and 85% versus 15% in 1988 through 1998 and 1999 through 2008 cohorts, respectively. Whereas patients≥9 years old in the 1977 through 1992 cohort had a higher proportion of positive cultures and more varied pathogens than younger patients, in the current series both groups had similar culture yields and aerobic constituencies. Anaerobes were isolated from only patients≥9 years old in both series. In cases positive for MRSA and other aggressive aerobes, initial findings prompted early drainage; outcomes were not compromised by adherence to the treatment protocol. The proportion of children<9 years requiring surgery for sinusitis-related SPA has remained a minority (15%-32.5%), without a clear upward trend over 25 years. Anaerobes continue not to factor in the younger subgroup, but more aggressive aerobic pathogens, including MRSA, have emerged. In such cases, surgical criteria that supersede age are triggered under the current treatment algorithm, and modification is not recommended.

Performance of Canadian clinical laboratories processing throat culture proficiency testing surveys

Proficiency testing results obtained from simulated throat swab cultures sent between 1999 and 2013 were analyzed to evaluate the ability of participants to process, analyze, and properly report results for these cultures. Eight percent of all pathogen-positive samples were reported as false negatives, and 11 % of the pathogen-negative ones were reported as false positives. More than 90 % of the participants achieved acceptable grades in each of the proficiency testing samples containing Streptococcus pyogenes. Laboratories were less successful in reporting other significant pathogens including group C and G streptococcus and Arcanobacterium haemolyticum, although an overall increase in performance was observed for each subsequent survey. Most laboratories recognized other respiratory pathogens as not being agents of pharyngitis; a common issue with these specimens was the suggestion of the organism’s clinical significance when their presence was reported. The presence of small colony-forming β-hemolytic streptococcus (Streptococcus anginosus group) proved to be challenging for many laboratories as 66 % of all unacceptable grades for pathogen-negative throat swabs occurred in these PT samples. Moreover, performance in this group did not improve with subsequent surveys. Results obtained in this study support the added value of clinical relevancy challenges for proficiency testing as laboratories that may not have problems with the analytical aspect of the testing process struggle with the appropriate interpretation of results.

Phylogenomic and MALDI-TOF MS analysis of Streptococcus sinensis HKU4T reveals a distinct phylogenetic clade in the genus Streptococcus.

Streptococcus sinensis is a recently discovered human pathogen isolated from blood cultures of patients with infective endocarditis. Its phylogenetic position, as well as those of its closely related species, remains inconclusive when single genes were used for phylogenetic analysis. For example, S. sinensis branched out from members of the anginosus, mitis, and sanguinis groups in the 16S ribosomal RNA gene phylogenetic tree, but it was clustered with members of the anginosus and sanguinis groups when groEL gene sequences used for analysis. In this study, we sequenced the draft genome of S. sinensis and used a polyphasic approach, including concatenated genes, whole genomes, and matrix-assisted laser desorption ionization-time of flight mass spectrometry to analyze the phylogeny of S. sinensis. The size of the S. sinensis draft genome is 2.06 Mb, with GC content of 42.2%. Phylogenetic analysis using 50 concatenated genes or whole genomes revealed that S. sinensis formed a distinct cluster with Streptococcus oligofermentans and Streptococcus cristatus, and these three streptococci were clustered with the “sanguinis group.” As for phylogenetic analysis using hierarchical cluster analysis of the mass spectra of streptococci, S. sinensis also formed a distinct cluster with S. oligofermentans and S. cristatus, but these three streptococci were clustered with the “mitis group.” On the basis of the findings, we propose a novel group, named “sinensis group,” to include S. sinensis, S. oligofermentans, and S. cristatus, in the Streptococcus genus. Our study also illustrates the power of phylogenomic analyses for resolving ambiguities in bacterial taxonomy.