Overcoming penicillin failures in the treatment of Group A streptococcal pharyngo-tonsillitis

Streptococcal Serology in Children With Stuttering

Introduction: Stuttering is a pronunciation disorder represented by repetitive perpetuations, duplications, or freezes of spoken words or syllables, as well as nervousness and cognitive shunning. Group A beta-hemolytic Streptococcus (GABHS) can lead to pediatric autoimmune neuropsychiatric disorders associated with streptococcal infection (PANDAS). Many case reports have proposed that stuttering is the result of a PANDAS, and that it can be identified together with Tourette syndrome, which shares many clinical characteristics with stuttering. Aim: The purpose of this study was to examine the association between streptococcal serology and stuttering in children. Method: The participants in this study are 26 children who stutter (CWS; mean age = 8.3 + 3.1 years) and 25 children who do not stutter (CWNS; mean age = 9.2 + 2.9 years). Participants were matched in terms of age (±3 months) and gender. We analyzed serum antistreptococcal antibodies [antistreptolysin O (ASO), anti-deoxyribonuclease B (anti-DNase B), and antistreptokinase] in both groups. Results: In the CWS group, ASO, anti-DNase B, and antistreptokinase were significantly higher than in the CWNS group (P < .0001, P < .0001, P < .0001). Conclusion: The higher serum antistreptococcal antibody amounts in CWS suggest that an increased autoimmune response against GAHBS may be the etiology of childhood stuttering. It has been suggested that CWS should be examined for autoimmune reactions, especially to GAHBS.

In Vivo Secretion of β-Lactamase-Carrying Outer Membrane Vesicles as a Mechanism of β-Lactam Therapy Failure

Outer membrane vesicles carrying β-lactamase (βLOMVs) protect bacteria against β-lactam antibiotics under experimental conditions, but their protective role during a patient’s treatment leading to the therapy failure is unknown. We investigated the role of βLOMVs in amoxicillin therapy failure in a patient with group A Streptococcus pyogenes (GAS) pharyngotonsillitis. The patient’s throat culture was examined by standard microbiological procedures. Bacterial vesicles were analyzed for β-lactamase by immunoblot and the nitrocefin assay, and in vivo secretion of βLOMVs was detected by electron microscopy. These analyses demonstrated that the patient’s throat culture grew, besides amoxicillin-susceptible GAS, an amoxicillin-resistant nontypeable Haemophilus influenzae (NTHi), which secreted βLOMVs. Secretion and β-lactamase activity of NTHi βLOMVs were induced by amoxicillin concentrations reached in the tonsils during therapy. The presence of NTHi βLOMVs significantly increased the minimal inhibitory concentration of amoxicillin for GAS and thereby protected GAS against bactericidal concentrations of amoxicillin. NTHi βLOMVs were identified in the patient’s pharyngotonsillar swabs and saliva, demonstrating their secretion in vivo at the site of infection. We conclude that the pathogen protection via βLOMVs secreted by the flora colonizing the infection site represents a yet underestimated mechanism of β-lactam therapy failure that warrants attention in clinical studies.

Reduced In Vitro Susceptibility of Streptococcus pyogenes to β-Lactam Antibiotics Associated with Mutations in the pbp2x Gene Is Geographically Widespread

Recently, two related Streptococcus pyogenes strains with reduced susceptibility to ampicillin, amoxicillin, and cefotaxime, antibiotics commonly used to treat S. pyogenes infections, were reported. The two strains had the same nonsynonymous (amino acid-substituting) mutation in the pbp2x gene, encoding penicillin-binding protein 2X (PBP2X). This concerning report led us to investigate our library of 7,025 genome sequences of type emm1, emm28, and emm89 S. pyogenes clinical strains recovered from intercontinental sources for mutations in pbp2x We identified 137 strains that, combined, had 37 nonsynonymous mutations in 36 codons in pbp2x Although to a lesser magnitude than the two previously published isolates, many of our strains had decreased susceptibility in vitro to multiple beta-lactam antibiotics. Many pbp2x mutations were found only in single strains, but 16 groups of two or more isolates of the same emm type had an identical amino acid replacement. Phylogenetic analysis showed that, with one exception, strains of the same emm type with the same amino acid replacement were clonally related by descent. This finding indicates that strains with some amino acid changes in PBP2X can successfully spread to new human hosts and cause invasive infections. Mapping of the amino acid changes onto a three-dimensional structure of the related Streptococcus pneumoniae PBP2X suggests that some substitutions are located in regions functionally important in related pathogenic bacterial species. Decreased beta-lactam susceptibility is geographically widespread in strains of numerically common emm gene subtypes. Enhanced surveillance and further epidemiological and molecular genetic study of this potential emergent antimicrobial problem are warranted.

Synergy and Mode of Action of Ceftazidime plus Quercetin or Luteolin on Streptococcus pyogenes

Streptococcus pyogenes causes streptococcal toxic shock syndrome. The recommended therapy has been often failure through the interfering of beta-lactamase-producing bacteria (BLPB). The present study was to investigate antibacterial activity, synergy, and modes of action of luteolin and quercetin using alone and plus ceftazidime against S. pyogenes. The MICs of ceftazidime, luteolin, and quercetin against all S. pyogenes were 0.50, 128, and 128 µg mL⁻¹, respectively. A synergistic effect was exhibited on luteolin and quercetin plus ceftazidime against these strains at fractional inhibitory concentration indices 0.37 and 0.27, respectively, and was confirmed by the viable count. These combinations increased cytoplasmic membrane (CM) permeability, caused irregular cell shape, peptidoglycan, and CM damage, and decreased nucleic acid but increased proteins in bacterial cells. Enzyme assay demonstrated that these flavonoids had an inhibitory activity against β-lactamase. In summary, this study provides evidence that the inhibitory mode of action of luteolin and quercetin may be mediated via three mechanisms: (1) inhibiting of peptidoglycan synthesis, (2) increasing CM permeability, and (3) decreasing nucleic acid but increasing the protein contents of bacterial cells. So, luteolin and quercetin propose the high potential to develop adjunct to ceftazidime for the treatment of coexistence of the BLPB and S. pyogenes infections.

Group A streptococci are protected from amoxicillin-mediated killing by vesicles containing β-lactamase derived from Haemophilus influenzae

OBJECTIVES

Group A streptococci (GAS) cause, among other infections, pharyngotonsillitis in children. The species is frequently localized with the Gram-negative respiratory pathogens non-typeable Haemophilus influenzae (NTHi) and Moraxella catarrhalis, which both produce outer membrane vesicles (OMVs). The aim of this study was to investigate whether OMVs isolated from NTHi contain functional β-lactamase and whether the OMVs hydrolyse amoxicillin and thus protect GAS from killing by the antibiotic.

METHODS

The antibiotic susceptibility of isolates was determined using the Etest. The resistance genes blaTEM-1 (encoding NTHi β-lactamase), bro-1 (encoding M. catarrhalis β-lactamase) and ftsI (encoding NTHi penicillin-binding protein 3) were searched for by PCR, followed by sequencing. OMVs were isolated by ultracentrifugation and the presence of β-lactamase was detected by western blots including specific rabbit polyclonal antibodies. The chromogenic substrate nitrocefin was used to quantify and compare the β-lactamase enzyme activity in the OMVs. The hydrolysis of amoxicillin by β-lactamase was estimated by an agar diffusion method.

RESULTS

We showed that OMVs released from β-lactam-resistant M. catarrhalis and NTHi contain functional β-lactamase that hydrolyses amoxicillin and protects GAS from killing by amoxicillin.

CONCLUSIONS

This is the first report of the presence of β-lactamase in NTHi OMVs. We suggest that OMV-derived β-lactamase from coinfecting pathogens such as NTHi and M. catarrhalis may contribute to the occasional treatment failures seen in GAS tonsillitis.

In Vitro Antibacterial Activity of Essential Oils against Streptococcus pyogenes

Streptococcus pyogenes plays an important role in the pathogenesis of tonsillitis. The present study was conducted to evaluate the in vitro antibacterial activities of 18 essential oils chemotypes from aromatic medicinal plants against S. pyogenes. Antibacterial activity of essential oils was investigated using disc diffusion method. Minimum Inhibitory Concentration of essential oils showing an important antibacterial activity was measured using broth dilution method. Out of 18 essential oils tested, 14 showed antibacterial activity against S. pyogenes. Among them Cinnamomum verum, Cymbopogon citratus, Thymus vulgaris CT thymol, Origanum compactum, and Satureja montana essential oils exhibited significant antibacterial activity. The in vitro results reported here suggest that, for patients suffering from bacterial throat infections, if aromatherapy is used, these essential oils, considered as potential antimicrobial agents, should be preferred.

StreptInCor: a candidate vaccine epitope against S. pyogenes infections induces protection in outbred mice

Infection with Streptococcus pyogenes (S. pyogenes) can result in several diseases, particularly in children. S. pyogenes M protein is the major virulence factor, and certain regions of its N-terminus can trigger autoimmune sequelae such as rheumatic fever in susceptible individuals with untreated group A streptococcal pharyngitis. In a previous study, we utilized a large panel of human peripheral blood cells to define the C-terminal protective epitope StreptInCor (medical identity), which does not induce autoimmune reactions. We recently confirmed the results in HLA-transgenic mice. In the present study, we extended the experimental assays to outbred animals (Swiss mice). Herein, we demonstrate high titers of StreptInCor-specific antibodies, as well as appropriate T-cell immune responses. No cross-reaction to cardiac myosin was detected. Additionally, immunized Swiss mice exhibited 87% survival one month after challenge with S. pyogenes. In conclusion, the data presented herein reinforce previous results in humans and animals and further emphasize that StreptInCor could be an effective and safe vaccine for the prevention of S. pyogenes infections.

Group a streptococcal vaccine candidates: potential for the development of a human vaccine

Currently there is no commercial Group A Streptococcus (GAS; S. pyogenes) vaccine available. The development of safe GAS vaccines is challenging, researchers are confronted with obstacles such as the occurrence of many unique serotypes (there are greater than 150 M types), antigenic variation within the same serotype, large variations in the geographical distribution of serotypes, and the production of antibodies cross-reactive with human tissue which can lead to host auto-immune disease. Cell wall anchored, cell membrane associated, secreted and anchorless proteins have all been targeted as GAS vaccine candidates. As GAS is an exclusively human pathogen, the quest for an efficacious vaccine is further complicated by the lack of an animal model which mimics human disease and can be consistently and reproducibly colonized by multiple GAS strains.

Sulphurous water inhalations in the prophylaxis of recurrent upper respiratory tract infections

OBJECTIVE

The aim of this study was to evaluate the efficacy and the effect of sulphurous thermal water inhalations in the treatment of the recurrent upper respiratory tract (RURT) infections in children.

METHODS

A total of 100 children with RURT infections were included. All children underwent a 12-day course warm vapour inhalations. For the inhalations, we used sulphurous thermal water in the group A, while physiological solution in the group B. At the beginning, at the end and 3 months after start, all children underwent medical history, ENT examination, plasma levels of immunoglobulins class E, G, A, M (IgE, IgG, IgA, IgM), subjective assessment of symptoms (VAS), nasal mucociliar transport time (NMTT) determination, and evaluation of frequency, duration, severity and social impact of RURT episodes.

RESULTS

Compared with group B, after the treatment and at the end of the study, in children treated with sulphurous thermal water, the serum concentration of IgE was significantly (p<0.05) lower (75.13+/-27.1mg/dl vs 96.87+/-41.3mg/dl; 74.23+/-26.2mg/dl vs 98.24+/-42.7 mg/dl), IgA titers were higher (238.14+/-122.1mg/dl vs 218.62+/-115.8 mg/dl; 239.72+/-119.7 mg/dl vs 210.46+/-107.3mg/dl), serum concentrations of IgG and IgM unchanged, VAS scores presented a significant (p<0.05) improvement (1.8+/-0.19 vs 6.8+/-0.54; 1.9+/-0.21 vs 6.9+/-0.61), NMTT was normal (11.15+/-1.59 min vs 17.63+/-2.17; 11.25+/-2.10 min vs 17.77+/-2.19 min) and frequency, duration, severity and social impact of RURT episodes were significantly (p<0.05) lower.

CONCLUSIONS

Our findings indicate that, in addition to their known effects, the sulphurous water also have an immunomodulant activity that contributes to their therapeutic effects.