Beta-haemolytic streptococci isolated from acute sore-throat patients: cause or coincidence? A case-control study in general practice

Is Streptococcus pyogenes a pathogen or passenger in uncomplicated acute sore throat? A systematic review and meta-analysis

OBJECTIVES

The objective was to estimate the probability that finding a Streptococcus pyogenes (Group A Streptococcus) in a throat swab in a patient with a sore throat reflects the aetiology. We also investigated to what extent this is influenced by age, carrier rates of S. pyogenes and climate zone.

METHODS

We conducted a comprehensive search of Medline and Scopus up until October 2023 for case-control studies reporting the prevalence of S. pyogenes in patients with a sore throat and healthy controls. We only included studies with separate data for children and adults. We used the positive and negative etiologic predictive value (P-EPV and N-EPV) to estimate the probability of a link between a sore throat and a finding of S. pyogenes.

RESULTS

We included 15 studies in our meta-analysis. The overall P-EPV for children and adults were 63% (49-74%) and 92% (87-95%), respectively. The P-EPV rose to 83% (64-93%) for children and 94% (90-97%) for adults when only patients with 3-4 Centor criteria were included. The overall N-EPV was 97% (96-98%) for children and 96% (95-97%) for adults.

CONCLUSIONS

Detecting S. pyogenes in adult patients with an uncomplicated acute sore throat is useful to rule in S. pyogenes as the likely aetiologic agent. The P-EPV significantly increased for children when those with 3-4 Centor criteria were selected. A negative throat swab is always useful for both children and adults to rule out S. pyogenes as the cause of the sore throat.

Similar Mortality among United States Veterans with Invasive and Non-Invasive Pneumonia due to Group B Streptococcus

Background

The nosology of non-invasive pneumonia due to Group B Streptococcus (GBS) is not well defined. This study compared clinical characteristics and outcomes of patients with invasive pneumonia and non-invasive pneumonia caused by GBS.

Methods

We conducted a retrospective cohort study among Veterans Affairs (VA) healthcare users between 2008 and 2017. Using data from electronic health records, we identified patients who had blood or respiratory cultures that grew GBS and had invasive pneumonia or non-invasive pneumonia. We analyzed patient and infection characteristics associated with all-cause mortality, including among the subset of patients with cultures that were monomicrobial for GBS.

Results

Among 1791 patients with GBS pneumonia, 646 (36%) cases were invasive and 1145 (64%) were non-invasive. Among those, 535 and 424 cases of invasive and non-invasive pneumonia, respectively, had cultures that were monomicrobial for GBS. All-cause 30-day mortality among those with monomicrobial GBS pneumonia was 15% for both those with invasive and non-invasive disease, respectively. Increasing age, severity of illness, healthcare exposure in the previous 90 days, and polymicrobial infection with Staphylococcus aureus were independently associated with all-cause mortality at 30 days.

Conclusions

In this large cohort, even when considering cases for which GBS was the only pathogen recovered, more than 40% of GBS pneumonia cases were non-invasive. All cause-mortality was comparable for invasive and non-invasive pneumonia. These findings suggests that the burden of GBS pneumonia may be greater than previously recognized by surveillance of invasive GBS disease and may inform treatment and prevention efforts.

Bacterial agents in vulvovaginitis and vaginal discharge: a 10-year retrospective study in the Netherlands

Vulvovaginitis is a common problem in the GP's practice. Causes are bacterial vaginosis (BV), Candida infection and sexually transmitted infections (STIs). Only if empirical treatment fails, a vaginal swab is sent in for culture and BV detection. However, without culture essential, bacterial pathogens may escape diagnosis. Many molecular BV assays have recently appeared on the marketplace, all quite differing in price and targets. However, for years, the Nugent score has been the gold standard for BV detection. We analysed retrospectively 10 years of microbiology results of vulvovaginal swabs, focusing on less frequently reported bacterial pathogens, and assessed the characteristics of BV diagnostics. Vulvovaginal swabs sent in between 2010 and 2020 from > 11,000 GP patients with vulvovaginitis associated symptoms, but negative STI tests, were analysed. First cultures and repeat cultures after at least 6 months were included in four age groups: < 12, 12-17, 18-51 and > 51 years. Candida species and BV were most frequently found, with the highest prevalence in premenopausal women. Haemophilus influenzae, beta-haemolytic streptococci, Streptococcus pneumoniae and Staphylococcus aureus were isolated in 5.6% of all cultures, with the highest percentages in children and postmenopausal women. If empirical treatment of vulvovaginitis fails, bacterial culture should be performed to detect all potentially pathogenic microorganisms to obtain a higher rate of successful diagnosis and treatment, avoiding unnecessary antimicrobial use and costs. For BV detection, molecular testing may seem attractive, but Nugent scoring still remains the low-cost gold standard. We recommend incorporating the above in the appropriate guidelines.

Group C beta hemolytic Streptococci as a potential pathogen in patients presenting with an uncomplicated acute sore throat - a systematic literature review and meta-analysis

Objective: The pathogenicity of beta-hemolytic Streptococcus group C (GCS) in patients attending for an uncomplicated acute sore throat is unknown and it was the objective to clarify this.Design: Systematic literature review with meta-analysis. Setting Medline and Scopus were searched from inception to February 2019, with searches of reference lists, Subjects case-control studies stating prevalence of GCS in patients as well as healthy controls presented for children and adults separately. Studies including patients already treated with antibiotics and studies focused on patients with HIV, malignancy or immunosuppression were not included. Main outcome measures Pooled prevalence of GCS was compared between patients and controls using chi-square and was further explored by calculating the positive etiologic predictive value (P-EPV) showing the post-test probability of a link between a sore throat and the bacterial finding. P-EPV for GCS was compared with that for group A Streptococci (GAS) using figures from the same publications and patients.Results: Eleven studies were included. The prevalence of GCS among patients versus controls was similar in children (3.15 versus 2.87%, p = .44) but for adults higher in patients (11%) than in controls (5.6%) (p < .0001). The P-EPV for finding GCS in children with a sore throat was 9.3% (0.0-41%). The corresponding P-EPV for GCS in adults with a sore throat was 53% (36-67%) while the corresponding P-EPV for GAS in adults was 94% (90-96%).Conclusions: GCS do not seem associated with the uncomplicated acute sore throat in children but there is support for an association in adults being weaker than for GAS. A possible consequence is to ignore GCS in otherwise healthy patients at their first visit for an uncomplicated sore throat. This would enable a stronger focus on the use of modern point of care tests (POCTs) to detect GAS.Key pointsThere is no current consensus on the pathogenicity of group C beta-hemolytic Streptococcus (GCS) in patients attending for an uncomplicated acute sore throat.This systematic literature review concludes it is unlikely that GCS is involved in the uncomplicated sore throat in otherwise healthy children.This meta-analysis found a moderate link between GCS and the uncomplicated sore throat in adults.The link in adults between GCS and the sore throat is much weaker than the corresponding link for group A beta-hemolytic Streptococcus.

Influence of a probiotic Lactobacillus casei strain on the colonisation with potential pathogenic streptococci and Staphylococcus aureus in the nasopharyngeal space of healthy men with a low baseline NK cell activity

The effect of a daily intake of the probiotic strain Lactobacillus casei Shirota (LcS) on the colonisation of pathogens, specifically streptococci and Staphylococcus aureus, in the nose and throat of healthy human volunteers with low natural killer cell activity, was investigated in a randomised and controlled intervention study. The study consisted of a 2-week run-in phase, followed by a 4-week intervention phase. The probiotic treatment group received a fermented milk drink with LcS, while the placebo group received an equally composed milk drink without the probiotic additive. To isolate potential pathogenic streptococci and Staph. aureus, samples from the pharynx, as well as of both middle nasal meati, were taken, once after the run-in phase and once at the end of the intervention phase. Isolated bacteria were identified as either Staph. aureus and α- or β-haemolytic streptococci in a polyphasic taxonomical approach based on phenotypic tests, amplified ribosomal DNA restriction analysis genotyping, and 16S rRNA gene sequencing of representative strains. Salivary secretory immunoglobulin A (SIgA) was used as marker of protective mucosal immunity to evaluate whether LcS treatment influenced SIgA production. No statistically significant effect could be determined for intervention with LcS on the incidence of Staph. aureus in the nasal space, Staph. aureus in the pharyngeal space or for β-haemolytic streptococci and Streptococcus pneumoniae in the pharyngeal space. Thus, the intervention did not influence the nasopharyngeal colonisation with Gram-positive potential pathogens. Production of salivary SIgA as a potential means of microbiota modulation was also not affected.

Guideline for the management of acute sore throat

The European Society for Clinical Microbiology and Infectious Diseases established the Sore Throat Guideline Group to write an updated guideline to diagnose and treat patients with acute sore throat. In diagnosis, Centor clinical scoring system or rapid antigen test can be helpful in targeting antibiotic use. The Centor scoring system can help to identify those patients who have higher likelihood of group A streptococcal infection. In patients with high likelihood of streptococcal infections (e.g. 3-4 Centor criteria) physicians can consider the use of rapid antigen test (RAT). If RAT is performed, throat culture is not necessary after a negative RAT for the diagnosis of group A streptococci. To treat sore throat, either ibuprofen or paracetamol are recommended for relief of acute sore throat symptoms. Zinc gluconate is not recommended to be used in sore throat. There is inconsistent evidence of herbal treatments and acupuncture as treatments for sore throat. Antibiotics should not be used in patients with less severe presentation of sore throat, e.g. 0-2 Centor criteria to relieve symptoms. Modest benefits of antibiotics, which have been observed in patients with 3-4 Centor criteria, have to be weighed against side effects, the effect of antibiotics on microbiota, increased antibacterial resistance, medicalisation and costs. The prevention of suppurative complications is not a specific indication for antibiotic therapy in sore throat. If antibiotics are indicated, penicillin V, twice or three times daily for 10 days is recommended. At the present, there is no evidence enough that indicates shorter treatment length.

Prospective surveillance of streptococcal sore throat in a tropical country

BACKGROUND

Acute rheumatic fever and rheumatic heart disease cause a high burden of disease in Fiji and surrounding Pacific Island countries, but little is known about the epidemiology of group A streptococcal (GAS) pharyngitis in the region. We designed a study to estimate the prevalence of carriage of beta-hemolytic streptococci (BHS) and the incidence of BHS culture-positive sore throat in school aged children in Fiji.

METHODS

We conducted twice-weekly prospective surveillance of school children aged 5 to 14 years in 4 schools in Fiji during a 9-month period in 2006, after an initial phase of pharyngeal swabbing to determine the prevalence of BHS carriage.

RESULTS

We enrolled 685 children. The prevalence of GAS carriage was 6.0%, while the prevalence of group C streptococcal (GCS) and group G streptococcal (GGS) carriage was 6.9% and 12%, respectively. There were 61 episodes of GAS culture-positive sore throat during the study period equating to an incidence of 14.7 cases per 100 child-years (95% CI, 11.2-18.8). The incidence of GCS/GGS culture-positive sore throat was 28.8 cases per 100 child-years (95% CI, 23.9-34.5). The clinical nature of GAS culture-positive sore throat was more severe than culture-negative sore throat, but overall was mild compared with that found in previous studies. Of the 101 GAS isolates that emm sequence typed there were 45 emm types with no dominant types. There were very few emm types commonly encountered in industrialized nations and only 9 of the 45 emm types found in this study are emm types included in the 26-valent GAS vaccine undergoing clinical trials.

CONCLUSIONS

GAS culture-positive sore throat was more common than expected. Group C and group G streptococci were frequently isolated in throat cultures, although their contribution to pharyngeal infection is not clear. The molecular epidemiology of pharyngeal GAS in our study differed greatly from that in industrialized nations and this has implications for GAS vaccine clinical research in Fiji and other tropical developing countries.

Emergence of respiratory Streptococcus agalactiae isolates in cystic fibrosis patients

Streptococcus agalactiae is a well-known pathogen for neonates and immunocompromized adults. Beyond the neonatal period, S. agalactiae is rarely found in the respiratory tract. During 2002-2008 we noticed S. agalactiae in respiratory secretions of 30/185 (16%) of cystic fibrosis (CF) patients. The median age of these patients was 3-6 years older than the median age CF patients not harboring S. agalactiae. To analyze, if the S. agalactiae isolates from CF patients were clonal, further characterization of the strains was achieved by capsular serotyping, surface protein determination and multilocus sequence typing (MLST). We found a variety of sequence types (ST) among the isolates, which did not substantially differ from the MLST patterns of colonizing strains from Germany. However serotype III, which is often seen in colonizing strains and invasive infections was rare among CF patients. The emergence of S. agalactiae in the respiratory tract of CF patients may represent the adaptation to a novel host environment, supported by the altered surfactant composition in older CF patients.

Long-term surveillance of invasive group A streptococcal disease in The Netherlands, 1994-2003

A nationwide laboratory-based surveillance study of invasive group A streptococcal (GAS) infections was conducted in The Netherlands from May 1994 until December 2003 (average population during this period was 15 729 704). Microbiologically invasive isolates were obtained from 1504 patients, with most (70%) isolates cultured from blood. There was a clear seasonal pattern in invasive streptococcal infections, with an estimated annual incidence that peaked in 1996 (4.0 cases/100 000 individuals/year) and was at its lowest in 1999 (2.0 cases/100 000 individuals/year). Twenty-eight different M-types were identified, of which the most frequent were M1 (339/1504, 23%), M3 (187/1504, 12%), M89 (174/1504, 12%), M28 (164/1504, 11%), M12 (109/1504, 7%) and M6 (55/1504, 4%). There was a high degree of variation in the relative annual contributions of the predominant M-types, but variations in M1 and M3 combined correlated with overall changes in the annual incidence. The contribution of the patient group aged > or = 56 years to all cases of invasive GAS disease increased during the study period, whereas that of the group aged 0-20 years decreased. A peak in the incidence of invasive GAS disease among the patient group aged 30-34 years did not vary during the study period, indicating that the high incidence of invasive GAS disease in this age group was age-specific rather than cohort-related.

Epidemiological features of invasive and noninvasive group A streptococcal disease in the Netherlands, 1992-1996

A prospective, nationwide, laboratory-based surveillance of invasive group A streptococcal infections was conducted in the Netherlands from 1992 through 1996. Clinical and demographic data were obtained and all isolates were T/M typed. All noninvasive group A streptococcal isolates were registered from 1994 through 1996. A total of 880 patients with invasive streptococcal disease were identified. The annual incidence was found to be 2.2 per 100,000. Predominant M types were M1 (21%), M3 (11%), M6 (5%), M12 (5%), and M28 (8%). Particular age and M-type distributions were observed in different clinical entities. The case-fatality rate was 18% overall, but it reached 59% among cases of toxic shock-like syndrome. Older age, necrotizing fasciitis, sepsis without focus, pneumonia, infection with type M1 or M3 strains, and underlying cardiopulmonary disease were associated with fatality. A total of 10,105 patients with noninvasive group A streptococcal disease were registered. These patients differed significantly from patients with invasive disease with regard to age distribution and primary foci of infection.

Penicillin for acute sore throat in children: randomised, double blind trial

OBJECTIVE

To assess the effectiveness of penicillin for three days and treatment for seven days compared with placebo in resolving symptoms in children with sore throat.

DESIGN

Randomised, double blind, placebo controlled trial.

SETTING

43 family practices in the Netherlands.

PARTICIPANTS

156 children aged 4-15 who had a sore throat for less than seven days and at least two of the four Centor criteria (history of fever, absence of cough, swollen tender anterior cervical lymph nodes, and tonsillar exudate). Interventions Patients were randomly assigned to penicillin for seven days, penicillin for three days followed by placebo for four days, or placebo for seven days.

MAIN OUTCOME MEASURES

Duration of symptoms, mean consumption of analgesics, number of days of absence from school, occurrence of streptococcal sequelae, eradication of the initial pathogen, and recurrences of sore throat after six months.

RESULTS

Penicillin treatment was not more beneficial than placebo in resolving symptoms of sore throat, neither in the total group nor in the 96 children with group A streptococci. In the groups randomised to seven days of penicillin, three days of penicillin, or placebo, one, two, and eight children, respectively, experienced a streptococcal sequela.

CONCLUSION

Penicillin treatment had no beneficial effect in children with sore throat on the average duration of symptoms. Penicillin may, however, reduce streptococcal sequelae.

The natural history of recurrent acute tonsillitis and a clinical trial of azithromycin for antibiotic prophylaxis

The pharmacokinetics of azithromycin (Zitromax), Pfizer Inc., USA) in tonsil tissue warranted the present trial. In 110 patients eligible for tonsillectomy because of recurrent acute tonsillitis, surgery was replaced by randomized medication with azithromycin 500 mg or placebo once per week for 6 months. Subsequently, their clinical condition and microbiology was monitored for 12 months. Acute tonsillitis developed in 40% of the patients who received azithromycin and in 49% of the patients in the placebo group (P > 0.05). Accordingly, 45% of all patients developed acute tonsillitis. Resistance to azithromycin was not detected. In this trial long-term medication with azithromycin was not efficacious in recurrent acute tonsillitis. As all patients were eligible for tonsillectomy according to current criteria, it is surprising that only 45% developed acute tonsillitis during the trial period. Therefore, the criteria for tonsillectomy in recurrent acute tonsillitis must be revised.

Epidemiology and virulence gene expression of intracellular group A streptococci in tonsils of recurrently infected adults

Intracellularly persistent group A streptococci (GAS, Streptococcus pyogenes) have been associated with recurrent tonsillopharyngitis and antibiotic treatment failure. As a supplementation of the published in vitro data, conventional bacteriology and molecular epidemiology was performed on material from 29 adult patients of a German army hospital with anamnestic signs of recurrent tonsillopharyngitis. Pre-surgery tonsil swabs and the surgically removed tonsils were examined with respect to growth of aerobic bacteria in absence and presence of antibiotics with exclusively extracellular activity. Under such antibiotic selection, Staphylococcus aureus and GAS were cultured from specimens of 13 and 3 patients, respectively. In every material GAS-positive by culture methods, the intracellular location of the penicillin-susceptible GAS isolates was confirmed by immunohistologic examination of tonsillar sections using a GAS-specific IgG antibody. The three intracellular GAS isolates were typed by emm gene sequencing and could be associated to types M6 and M49 (two isolates). The bacteria were serially passaged on sheep blood agar, and semiquantitative mRNA analysis from virulence genes was performed using bacteria of the 4th and 25th passage after isolation. An M-type-specific pattern of virulence gene expression and different gene expression levels in relation to the passage number were observed.

Potentially virulent strains and high colony counts of group A beta-haemolytic streptococci in pharyngitis patients having a delayed recovery or a complication

T serotyping and M and exotoxin genotyping were performed on strains from 367 streptococcal pharyngitis patients in Dutch general practice. Potentially virulent strains of group A beta-haemolytic streptococci, such as T1M1 and T3M3 subtypes and strains expressing speA and speC, and a high number of colony counts did not occur more frequently in the 166 (45%) more seriously ill patients, defined as those who showed a delayed recovery or a complication.