Evaluation of bacterial interference and beta-lactamase production in management of experimental infection with group A beta-hemolytic streptococci

Molecular Cloning and Docking of speB Gene Encoding Cysteine Protease With Antibiotic Interaction in Streptococcus pyogenes NBMKU12 From the Clinical Isolates

Streptococcus pyogenes causes a variety of diseases ranging from mild diseases to severe invasive infections which result in significant morbidity and mortality. This study focuses on the antibiotic resistance of S. pyogenes and their interaction with cysteine protease. Around 36 beta-hemolytic isolates were collected from the clinical lab, of which seven isolates (19.4%) were identified as Streptococcus pyogenes. One of the seven isolates was collected from a urinary tract infection, which was identified by antibody agglutination and MALTI-TOF-MS, and it is designated as S. pyogenes NBMKU12. Around 8.3 to 66.6 % of the isolates were found to be resistant to one or more antimicrobial agents, especially, penicillin-G resistance was exhibited by 29.1% of the isolates. In the NBMKU12 isolate, the beta lactem (TEM) gene was detected among the 13 antibiotic genes for which it was tested. Furthermore, when analysis for presence of 13 virulence genes were carried out in NBMKU12 isolate, only speJ and speB were detected. The speB (streptococcal pyrogenic exotoxin B) encoding cysteine protease gene was cloned. This was followed by performing DNA sequencing to understand the putative cysteine protease interaction with antibiotics, inhibitors, and substrate. The speB gene consists of 1197 nucleotides and encodes a protein with multiple domains, including a signal peptide (aa 1-22), an inhibitor region (aa 27-156), and a catalytic cysteine domain (aa 160-367). The signal peptide cleavage site is predicted between Ala22 and Asn23. The putative 398 amino acid residues were found to have a theoretical pI of 8.76 and a molecular mass of 43,204.36 Da. The tested culture supernatants of NBMKU12 isolate exhibited the proteolytic activity against casein, papaya and pineapple used as substrates. The proteolytic activity suggests the expression of speB gene. Molecular docking analysis of cysteine protease showed that erythromycin (bond length 2.41 Å), followed by chloramphenicol (2.51 Å), exhibited a strong interaction; while penicillin-G (3.24 Å) exhibited a weak interaction, and this factor could be considered as a cause for penicillin-G resistance. The present study contributes to a better understanding of speB gene encoding cysteine protease, antibiotic resistance, and their interaction in the isolate, S. pyogenes NBMKU12. The antibiotics and cysteine protease interaction study confirms the resistance or sensitivity of S. pyogenes. Hence, it could be hypothesized that the isolate NBMKU12 is resistant to most of the tested antibiotics, and this resistance might be a cause for mutation.

Alloiococcus otitidis Forms Multispecies Biofilm with Haemophilus influenzae: Effects on Antibiotic Susceptibility and Growth in Adverse Conditions

Otitis media with effusion (OME) is a biofilm driven disease and commonly accepted otopathogens, such as Haemophilus influenzae, Streptococcus pneumonia, and Moraxella catarrhalis, have been demonstrated to form polymicrobial biofilms within the middle ear cleft. However, Alloiococcus otitidis (A. otitidis), which is one of the most commonly found bacteria within middle ear aspirates of children with OME, has not been described to form biofilms. The aim of this study was to investigate whether A. otitidis can form biofilms and investigate the impact on antibiotic susceptibility and survivability in polymicrobial biofilms with H. influenzae in vitro. The ability of A. otitidis to form single-species and polymicrobial biofilms with H. influenzae was explored. Clinical and commercial strains of A. otitidis and H. influenzae were incubated in brain heart infusion with and without supplementation. Biofilm was imaged using confocal laser scanning microscopy and scanning electron microscopy. Quantification of biofilm biomass and viable bacterial number was assessed using crystal violet assays and viable cell counting in both optimal growth conditions and in adverse growth conditions (depleted media and sub-optimal growth temperature). Antimicrobial susceptibility and changes in antibiotic resistance of single-species and multi-species co-culture were assessed using a microdilution method to assess minimal bactericidal concentration and E-test for amoxicillin and ciprofloxacin. A. otitidis formed single-species and polymicrobial biofilms with H. influenzae. Additionally, whilst strain dependent, combinations of polymicrobial biofilms decreased antimicrobial susceptibility, albeit a small magnitude, in both planktonic and polymicrobial biofilms. Moreover, A. otitidis promoted H. influenzae survival by increasing biofilm production in depleted media and at suboptimal growth temperature. Our findings suggest that A. otitidis may play an indirect pathogenic role in otitis media by altering H. influenzae antibiotic susceptibility and enhancing growth under adverse conditions.

Treatment Challenges of Group A Beta-hemolytic Streptococcal Pharyngo-Tonsillitis

Introduction  Despite its in vitro efficacy, penicillin often fails to eradicate Group A β-hemolytic streptococci (GABHS) from patients with acute and relapsing pharyngo-tonsillitis (PT). Objective  This review of the literature details the causes of penicillin failure to eradicate GABHS PT and the therapeutic modalities to reduce and overcome antimicrobial failure. Data Synthesis  The causes of penicillin failure in eradicating GABHS PT include the presence of β lactamase producing bacteria (BLPB) that "protect" GABHS from any penicillin; the absence of bacteria that interfere with the growth of GABHS; co-aggregation between GABHS and Moraxella catarrhalis; and the poor penetration of penicillin into the tonsillar tissues and the tonsillo-pharyngeal cells, which allows intracellular GABHS and Staphylococcus aureus to survive. The inadequate intracellular penetration of penicillin can allow intracellular GABHS and S. aureus to persist. In the treatment of acute tonsillitis, the use of cephalosporin can overcome these interactions by eradicating aerobic BLPB (including M. catarrhalis), while preserving the potentially interfering organisms and eliminating GABHS. Conclusion  In treatment of recurrent and chronic PT, the administration of clindamycin, or amoxicillin-clavulanic acid, can eradicate both aerobic and anaerobic BLPB, as well as GABHS. The superior intracellular penetration of cephalosporin and clindamycin also enhances their efficacy against intracellular GABHS and S. aureus.

Systematic review of factors contributing to penicillin treatment failure in Streptococcus pyogenes pharyngitis

Objective

Review the evidence for various explanations for microbiologic treatment failure following use of penicillin in group A streptococcal (GAS) tonsillopharyngitis.

DATA SOURCE

Systematic review of the literature based on Medline and EMBASE searches, and review of reference lists of included studies.

RESULTS

The explanations for penicillin treatment failure in GAS tonsillopharyngitis include 1) carrier state, 2) lack of compliance, 3) recurrent exposure, 4) in vivo copathogenicity of β-lactamase–producing normal pharyngeal flora, 5) in vivo bacterial coaggregation, 6) poor antibiotic penetration to tonsillopharyngeal tissue, 7) in vivo eradication of normal protective flora, 8) early initiation of antibiotic therapy resulting in suppression of an adequate host immune response, 9) intracellular localization of GAS, 10) GAS tolerance to penicillin, 11) contaminated toothbrushes or orthodontic appliances, and 12) transmission from the family pet. There is very little type I or II evidence to support any of the above-cited explanations for treatment failure in GAS tonsillopharyngitis; available studies are mostly observational (in patients) or laboratory-based without clinical confirmation.

CONCLUSION

Multiple explanations have been offered by investigators to explain penicillin treatment failures in GAS tonsillopharyngitis, but the evidence base to support the proposed explanations is generally weak by current standards. Further research is needed to better understand the mechanism(s) of penicillin treatment failure in GAS tonsillopharyngitis.

The effects of antimicrobials and exposure to smoking on bacterial interference in the upper respiratory tract of children

Interactions between micro-organisms that include antagonism (interference) and synergism maintain balance between members of the normal endogenous flora, and play a role in preventing colonization by potential pathogens. Bacteria with interference capability of potential respiratory tract pathogens include alpha-hemolytic streptococci, non-hemolytic streptococci, Prevotella spp. and Peptostreptococcus spp. The role of bacterial interference in the occurrence of upper respiratory tract infections and its effect on their eradication is discussed. The infections include otitis media, sinusitis and pharyngo-tonsillitis. Treatment with antimicrobial agents and direct and indirect exposure to smoking, can affect the balance between the interfering organisms and potential pathogens. Introduction into the indigenous microflora of low virulence bacterial strains that are capable of interfering with colonization and infection with virulent organisms has been used to prevent the failure of antimicrobials in the treatment of pharyngo-tonsillitis and otitis media.

Evaluation of potential factors contributing to microbiological treatment failure in Streptococcus pyogenes pharyngitis

BACKGROUND

A cohort study of children with pharyngitis aged two to 16 years was conducted to assess the role of microbial and host factors in group A beta-hemolytic streptococcus (GABHS) microbiological treatment failure.

METHODS

GABHS-infected children had pharyngeal swabs repeated two to five days after completing a 10-day course of penicillin V. M and T typing, and pulsed field gel electrophoresis were performed on the isolates, and the isolates were evaluated for tolerance. Patient characteristics and clinical features were noted and nasopharyngeal swabs for respiratory viruses were taken at enrolment.

RESULTS AND CONCLUSIONS

Of 286 patients enrolled, 248 (87%) could be evaluated. GABHS was cultured from 104 patients (41.9%), of whom 33 (33.7%) had microbiological treatment failures on follow-up. Although there was a trend toward failure for younger children (mean 6.5+/-2.4 years versus 7.3+/-2.4 years, P=0.07) and M type 12 (24% versus 10%, P=0.08), no factors were associated with treatment failure.

Rate of eradication of group A beta-hemolytic streptococci in children with pharyngo-tonsillitis by amoxicillin and cefdinir

BACKGROUND

Cephalosporins were found to be more effective than penicillins in the eradication of group A beta-hemolytic streptococcal (GABHS) from tonsillar tissues. This study investigated the effect of amoxicillin and cefdinir therapies on the rate of eradication of GABHS from the tonsils of children with acute pharyngo-tonsillitis (PT).

PATIENTS AND METHODS

Of 50 children suffering from PT 25 were treated with amoxicillin (40 mg/(kg d) or 250 mg every 8 h) and 25 with cefdinir (14 mg/(kg d) or 600 mg once a day) for 10 days. Pharyngo-tonsillar cultures were obtained from all children before treatment and on the 1st, 2nd, 3rd, 4th, 7th, and 12th days.

RESULTS

GABHS was eradicated more rapidly from children treated with cefdinir as compared to those receiving amoxicillin. A smaller number of patients with GABHS were found in those treated with cefdinir as compared to amoxicillin throughout the treatment period. Eradication of GABHS from 68% (8 of 25 patients) was noted in those treated with cefdinir after 2 days and those treated with amoxicillin after 4 days. The differences between the number of patients who had a bacteriological cure between those receiving cefdinir to those getting amoxicillin was statistical significant at day 4 (32% vs. 8%). At the end of therapy GABHS was recovered from 5 (20%) and 2 (8%) of the patients. The group that received cefdinir, had a more rapid reduction in fever on the first after initiation of therapy as compared to those receiving amoxicillin. The fever reduction in those receiving cefdinir occurred a day earlier than in those getting amoxicillin.

CONCLUSIONS

Fever was reduced and GABHS was eradicated more rapidly from children treated with cefdinir as compared to amoxicillin.

Frequency of symptomatic relapses of group A beta-hemolytic streptococcal tonsillopharyngitis in children from 4 pediatric practices following penicillin, amoxicillin, and cephalosporin antibiotic treatment

The objective was to determine the frequency of early symptomatic relapses following antibiotic treatment for group A beta-hemolytic streptococcal (GABHS) tonsillopharyngitis in children from Rochester, New York; Houston, Texas; Spokane, Washington; and Los Angeles, California (2004--2006). The study included 4278 patients. The proportion with a bacteriologic relapse of GABHS tonsillopharyngitis within 1 to 5 days of completing a 10-day treatment course was 8% (penicillin and bicillin), 6% (amoxicillin), 2% (first-generation cephalosporin), and 1% (second-generation and third-generation cephalosporin; P = .0001); symptomatic relapses occurred within 6 to 20 days after completion of therapy in 16%, 14%, 9%, and 7% of cases (P = .0001). Cases from New York and Washington had higher penicillin or amoxicillin failure rates than cases from Texas and California. The frequency of symptomatic relapses of GABHS tonsillopharyngitis, therefore, differs according to the antibiotic treatment selected; the trend for such relapses being penicillin or amoxicillin > cephalosporins although geographic differences may occur.

Cephalosporins in overcoming beta-lactamase-producing bacteria and preservation of the interfering bacteria in the treatment of otitis, sinusitis and tonsillitis

The treatment of upper respiratory tract infections (URTIs) is complicated by the resurgence of beta-lactamase-producing bacteria (BLPB) and the absence of interfering bacteria. BLPB can have a direct pathogenic impact in causing the infection as well as an indirect impact through their ability to produce the enzyme beta-lactamase. BLPB may not only survive penicillin therapy but can also protect other penicillin-susceptible bacteria from penicillin. In this review, the clinical in vitro and in vivo evidence supporting the role of these organisms in the increased failure rate of penicillin in eradication of otitis, sinusitis and pharyngo-tonsillitis is outlined and the implication of that increased rate on the management of infections is discussed. Bacteria with interference capability of potential respiratory pathogens can prevent colonization and subsequent invasion by these organisms. These include alpha-hemolytic streptococci, nonhemolytic streptococci and Prevotella and Peptostreptococcus spp. Treatment with antimicrobials can affect the balance between the interfering organisms and potential pathogens. The role of bacterial interference in URTIs and its effect on their treatment is discussed. The use of some of the cephalosporins that are able to overcome the effect of BLPB and preserve the beneficial interfering bacteria can overcome and modulate these phenomena and achieve better cure of URTIs.

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

The causes of penicillin failure in eradicating Group A beta-hemolytic streptococcal pharyngo-tonsillitis (GABHS PT) are described. These include the presence of beta-lactamase producing bacteria that "protect" Group A beta-hemolytic streptococci (GABHS) from penicillins; the absence of bacteria that interfere with the growth of GABHS; co-aggregation between GABHS and Moraxella catarrhalis; and the poor penetration of penicillin into the tonsillar tissues and the tonsillo-pharyngeal cells. The use of antimicrobials that can overcome and modulate these phenomena and achieve better cure of the infection is described.

Comparison of European and U.S. results for cephalosporin versus penicillin treatment of group A streptococcal tonsillopharyngitis

The outcome of cephalosporin versus penicillin treatment of group A streptococcal tonsillopharyngitis may differ between Europe and the USA. In the present study, Medline, Embase, reference lists, and abstract searches were used to identify randomized, controlled trials of cephalosporin versus penicillin treatment of group A streptococcal (GAS) tonsillopharyngitis. The outcomes of interest were bacteriologic and clinical cure rates from investigations conducted in Europe versus those conducted in the USA. Forty-seven trials involving 11,426 patients were included in the meta-analyses. For the comparison of 10 days of treatment with cephalosporins versus 10 days of treatment with penicillin, there were ten European and 25 U.S. trials, all involving pediatric subjects. The overall odds ratio (OR) favored cephalosporins more strongly in bacteriologic cure rate in Europe (OR=4.27, p<0.00001) than in the USA (OR=2.70, p<0.00001). Studies of 4-5 days of cephalosporin treatment versus 10 days of penicillin treatment were also analyzed. For nine European trials, the OR significantly favored cephalosporins (OR=1.30, p=0.03) in bacteriologic cure rates, but not as strongly as in the USA, (OR=2.41, p<0.00001). When results for 4-5 days of cephalosporin treatment were divided into pediatric versus adult populations, the differences in bacteriologic eradication rates obtained with cephalosporins were more pronounced in children. The likelihood of bacteriologic and clinical failure of GAS tonsillopharyngitis treatment in both European and U.S. patients is significantly less if a 10-day course of oral cephalosporin is prescribed, and is at least similar, if not significantly less, with a 4- to 5-day course of oral cephalosporin compared with a 10-day course of oral penicillin.

Efficacy of penicillin versus cefdinir in eradication of group A streptococci and tonsillar flora

Core tonsillar cultures were obtained from 40 children with recurrent tonsillitis treated with either penicillin or cefdinir. Group A beta-hemolytic streptococci were isolated from 11 penicillin- and 3 cefdinir-treated (P < 0.001) patients. beta-Lactamase producers were recovered from 17 penicillin- and 3 cefdinir-treated (P < 0.01) patients. Inhibiting alpha-hemolytic streptococci were isolated less often from penicillin-treated patients than from cefdinir-treated patients.

The role of bacterial interference in otitis, sinusitis and tonsillitis

Bacterial interactions that include antagonism (interference) and synergism help maintain balance between the members of the normal endogenous flora. Alpha-streptococci that predominate in the normal respiratory tract flora attracted most attention in studies of bacterial interference. Other organisms that possess interfering characteristics in upper respiratory tract infections (URTIs) are nonhemolytic streptococci, and Prevotella and Peptostreptococcus spp. The production of bacteriocins by some microorganisms is one of the important mechanisms of interference. The role of bacterial interference in the development of URTI and its effect on the eradication of these infections is discussed. These infections include pharyngo-tonsillitis, otitis media, and sinusitis. Treatment with various antimicrobial agents can affect the balance between members of the oro-pharyngeal bacterial flora and interfering organisms. Implantation into the indigenous microflora of low virulence bacterial strains that are potentially capable of interfering with colonization and infection with other more virulent organisms has been used in preliminary studies as a means of coping with the failure of antimicrobials in the treatment of several URTI.

Long-term effects on the nasopharyngeal flora of children following antimicrobial therapy of acute otitis media with cefdinir or amoxycillin-clavulanate

The effect on the nasopharyngeal bacterial flora of 10 days of amoxycillin-clavulanate or cefdinir antimicrobial therapy was studied in 50 children with acute otitis media. Before therapy, 17 potential pathogens (Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis) were isolated from the nasopharynx of 14 (56%) of those treated with amoxycillin-clavulanate, and 20 potential pathogens were recovered from 15 (60%) of those treated with cefdinir. Following therapy, at days 12-15, the number of potential pathogens was reduced to a similar extent with both therapies, to three in those treated with amoxycillin-clavulanate and two in those treated with cefdinir. However, the number of potential pathogens rebounded faster in those treated with amoxycillin-clavulanate as compared with cefdinir in the two subsequent specimens taken at days 30-35 and 60-65 (12 and 18 in the amoxycillin-clavulanate group, and six and nine in the cefdinir group, P < 0.01 and P < 0.001, respectively). Differences between the groups were also noted in the recovery of organisms with interfering capability. Immediately following amoxycillin-clavulanate therapy, the number of interfering organisms declined from 54 to 13, while following cefdinir treatment their number was reduced from 59 to 39 (P < 0.001). The differences between the two therapy groups persisted in the two later specimens taken at days 30-35 and 60-65 (25 and 38 in the amoxycillin-clavulanate group, and 52 and 51 in the cefdinir group, P < 0.001 and P < 0.05, respectively). This study illustrates the potential beneficial effect of using a narrow-spectrum antimicrobial that selectively spares the interfering organisms while eliminating pathogens. The benefit of such therapy is the prevention of reacquisition of pathogenic bacteria in the nasopharynx. In contrast, utilization of a broad-spectrum antimicrobial is associated with prolonged absence of inhibitory organisms and rapid recolonization with pathogens.

Effect of antimicrobial therapy with amoxicillin and cefprozil on bacterial interference and beta-lactamase production in the adenoids

To compare the effects on the bacterial flora of the adenoids of antimicrobial therapy with amoxicillin or cefprozil, we enrolled in a prospective randomized study 60 children scheduled for elective adenoidectomy because of recurrent otitis media. They were randomized before surgery into 3 groups of 20 patients each: a no-therapy group, and groups with 10 days of either amoxicillin or cefprozil therapy. Core adenoid materials were quantitatively cultured for aerobic and facultative bacteria. The in vitro ability of alpha-hemolytic streptococci (AHS) to inhibit the growth of non-type B Haemophilus influenzae and Streptococcus pneumoniae was determined. The number of organisms in adenoids obtained from patients treated with either antibiotic was reduced as compared to that in adenoids from controls. However, in patients treated with amoxicillin, a significant decline in the number of AHS, and an increase (in Staphylococcus aureus) or no change in the number of other beta-lactamase-producing bacteria (BLPB) was noted. In contrast, in those treated with cefprozil, no change was noted in the frequency of recovery of AHS, and the number of BLPB decreased. Interfering AHS were more often recovered in patients treated with cefprozil. We conclude that the adenoids contain more interfering AHS after therapy with a second-generation oral cephalosporin (cefprozil) than after amoxicillin therapy. This study suggests a potential beneficial effect of using an antimicrobial that selectively spares interfering AHS while inhibiting BLPB.

Beta-lactamase-producing nontypeable Haemophilus influenzae fails to protect Streptococcus pneumoniae from amoxicillin during experimental acute otitis media

Acute otitis media (AOM) is the most common reason for outpatient antimicrobial therapy. Mixed infections pose a potential problem, since the first-line drug used for the treatment of AOM, amoxicillin, can be neutralized by beta-lactamase-producing pathogens of the upper respiratory tract. To study the effects of a 5-day course of amoxicillin on a mixed middle ear infection, rats were challenged with Streptococcus pneumoniae alone or in combination with beta-lactamase-producing nontypeable Haemophilus influenzae. Amoxicillin was introduced at the clinical peak of the infection. Local and systemic changes were monitored by otomicroscopy, bacterial culture, and analysis of histological changes and the expression of the transforming growth factor beta (TGF-beta) gene. beta-Lactamase-producing H. influenzae did not demonstrate an ability to protect S. pneumoniae. Amoxicillin eradicated the pneumococci in all treated animals but increased to some degree the ability of H. influenzae to persist at the site of infection. Thus, only an insignificant acceleration of the resolution of the AOM caused by a mixture of pathogens was observed during treatment. Moderate to major morphological changes could not be avoided by treatment of the mixed infections, but a slight downregulation of TGF-beta expression was observed. In contrast to infections caused by a single pathogen, the mixed infections induced white plaques in the tympanic membrane at a remarkably high frequency independent of treatment. These experimental findings constitute support for further studies of antimicrobial drugs and AOM caused by bacteria with and without mechanisms of antibiotic resistance.

Meta-analysis of Cephalosporins versus Penicillin for Treatment of Group A Streptococcal Tonsillopharyngitis in Adults

We conducted a meta-analysis of 9 randomized controlled trials (involving 2113 patients) comparing cephalosporins with penicillin for treatment of group A beta -hemolytic streptococcal (GABHS) tonsillopharyngitis in adults. The summary odds ratio (OR) for bacteriologic cure rate significantly favored cephalosporins, compared with penicillin (OR,1.83; 95% confidence interval [CI], 1.37-2.44); the bacteriologic failure rate was nearly 2 times higher for penicillin therapy than it was for cephalosporin therapy (P=.00004). The summary OR for clinical cure rate was 2.29 (95% CI, 1.61-3.28), significantly favoring cephalosporins (P<.00001). Sensitivity analyses for bacterial cure significantly favored cephalosporins over penicillin in trials that were double-blinded and of high quality, trials that had a well-defined clinical status, trials that performed GABHS serotyping, trials that eliminated carriers from analysis, and trials that had a test-of-cure culture performed 3-14 days after treatment. This meta-analysis indicates that the likelihood of bacteriologic and clinical failure in the treatment of GABHS tonsillopharyngitis is 2 times higher for oral penicillin than for oral cephalosporins.

Meta-analysis of cephalosporin versus penicillin treatment of group A streptococcal tonsillopharyngitis in children

OBJECTIVE

To conduct a meta-analysis of randomized, controlled trials of cephalosporin versus penicillin treatment of group A beta-hemolytic streptococcal (GABHS) tonsillopharyngitis in children.

METHODOLOGY

Medline, Embase, reference lists, and abstract searches were conducted to identify randomized, controlled trials of cephalosporin versus penicillin treatment of GABHS tonsillopharyngitis in children. Trials were included if they met the following criteria: patients <18 years old, bacteriologic confirmation of GABHS tonsillopharyngitis, random assignment to antibiotic therapy of an orally administered cephalosporin or penicillin for 10 days of treatment, and assessment of bacteriologic outcome using a throat culture after therapy. Primary outcomes of interest were bacteriologic and clinical cure rates. Sensitivity analyses were performed to assess the impact of careful clinical illness descriptions, compliance monitoring, GABHS serotyping, exclusion of GABHS carriers, and timing of the test-of-cure visit.

RESULTS

Thirty-five trials involving 7125 patients were included in the meta-analysis. The overall summary odds ratio (OR) for the bacteriologic cure rate significantly favored cephalosporins compared with penicillin (OR: 3.02; 95% confidence interval [CI]: 2.49-3.67, with the individual cephalosporins [cephalexin, cefadroxil, cefuroxime, cefpodoxime, cefprozil, cefixime, ceftibuten, and cefdinir] showing superior bacteriologic cure rates). The overall summary OR for clinical cure rate was 2.33 (95% CI: 1.84-2.97), significantly favoring the same individual cephalosporins. There was a trend for diminishing bacterial cure with penicillin over time, comparing the trials published in the 1970s, 1980s, and 1990s. Sensitivity analyses for bacterial cure significantly favored cephalosporin treatment over penicillin treatment when trials were grouped as double-blind (OR: 2.31; 95% CI: 1.39-3.85), high-quality (OR: 2.50; 95% CI: 1.85-3.36) trials with well-defined clinical status (OR: 2.12; 95% CI: 1.54-2.90), with detailed compliance monitoring (OR: 2.85; 95% CI: 2.33-3.47), with GABHS serotyping (OR: 3.10; 95% CI: 2.42-3.98), with carriers eliminated (OR: 2.51; 95% CI: 1.55-4.08), and with test of cure 3 to 14 days posttreatment (OR: 3.53; 95% CI: 2.75-4.54). Analysis of comparative bacteriologic cure rates for the 3 generations of cephalosporins did not show a difference.

CONCLUSIONS

This meta-analysis indicates that the likelihood of bacteriologic and clinical failure of GABHS tonsillopharyngitis is significantly less if an oral cephalosporin is prescribed, compared with oral penicillin.

Antibacterial therapy for acute group a streptococcal pharyngotonsillitis: short-course versus traditional 10-day oral regimens

The objective of this review is to examine the use of short-course antibacterial therapy of group A beta-hemolytic streptococcal (GABHS) pharyngotonsillitis, compared with traditional 10-day therapy. In preparing this paper we reviewed the medical literature of studies comparing 10 days of penicillin with shorter courses of antibacterial therapy. Short-course therapy of 6 days of amoxicillin, 4 to 5 days of cephalosporins, and 5 days of azithromycin was found to be as, or more effective than traditional 10-day penicillin therapy. The benefits of short-course therapy include superior compliance and adherence, lower incidence of adverse effects, less effect on the bacterial flora, improved patient and parent satisfaction, and lower drug costs. In conclusion, short courses of amoxicillin, cephalosporins, and macrolides provide superior or equal efficacy to a 10-day course of penicillin therapy in the treatment of GABHS pharyngotonsillitis.

Efficacy of penicillin vs. amoxicillin in children with group A beta hemolytic streptococcal tonsillopharyngitis

The purpose of this study was to compare the bacteriologic and clinical efficacy of oral penicillin versus amoxicillin as first-line therapy for group A beta-hemolytic streptococcal (GABHS) tonsillopharyngitis. The prospective observational study was conducted over 18 months (January 2000-June 2001). Children enrolled had acute onset of symptoms and signs and a laboratory-documented GABHS tonsillopharyngitis illness. Follow-up examination and laboratory testing occurred 10 +/- 4 days following completion of treatment. In total, 389 patients were enrolled (intent-to-treat group): 195 received penicillin V and 194 received amoxicillin. Fifty-six of the penicillin-treated and 57 amoxicillin-treated patients refused to take the drug, or were noncompliant, or did not return for the follow-up visit, leaving 276 patients in the per-protocol group: 139 penicillin-treated and 137 amoxicillin-treated. Bacteriologic cure for amoxicillin-treated children occurred in 76% versus 64% in the penicillin-treated children (p = 0.04). The clinical cure rate for amoxicillin-treated children was 84% compared to 73% in the penicillin-treated children (p = 0.03). Since treatment allocation was not randomized, logistic regression analysis was used to adjust for treatment group differences. The odds ratio (OR) estimate for cure for patients in the amoxicillin versus penicillin V treatment group remained significant (OR = 1.84, 95% confidence interval 1.02-3.29); the same was true for dinical cure (OR = 1.99, 95% CI = 1.02-3.87). Amoxicillin may be superior to penicillin for bacteriologic and clinical cure of GABHS tonsillopharyngitis.

Neutrophils are hyperactive in recurrent tonsillitis

The pathogenesis of recurrent tonsillitis has not been fully explored. Most studies in this field have focused on pathogenic bacteria whereas less research has been done concerning the host defense. In earlier studies it was shown that there is an active cellular defense in the tonsillar surface secretion, consisting of phagocytes, and therefore in this study the possibility that this defense is altered in patients with recurrent tonsillitis was explored. Neutrophils were obtained from tonsillar surface secretions in eight patients with recurrent tonsillitis and eight healthy volunteers and the capacity of the neutrophils to respond to chemotactic stimuli was examined in an in vitro system. A significantly higher fraction of the neutrophils obtained from the patients with recurrent tonsillitis responded to chemotactic stimuli compared to those obtained from the healthy volunteers. It is concluded that there is a hyperactive cellular defense in the tonsillar surface secretion in patients with recurrent tonsillitis. This finding and its significance in the pathogenesis of recurrent tonsillitis are discussed.

The role of beta-lactamase producing bacteria and bacterial interference in streptococcal tonsillitis

The causes of penicillin failure in eradicating group A beta-haemolytic streptococcal pharyngo-tonsillitis are described. The mechanisms accounting for the failure include the presence in the tonsils of beta-lactamase producing bacteria and the absence of bacterial interference. The use of antimicrobials that can overcome and modulate these two phenomena and achieve better cure of the infection is described.

Microbial factors leading to recurrent upper respiratory tract infections

The treatment or prophylaxis of upper respiratory tract infections such as otitis media, sinusitis and tonsillitis with penicillins can generate bacterial resistance caused by production of beta-lactamase or changes in the penicillin-binding proteins. This resistance can spread in the community even to untreated individuals. The prevalence of resistant organisms tends to increase in the winter months. Beta-lactamase-producing bacteria may interfere with the eradication of penicillin-susceptible organisms and may account for substantial numbers of therapeutic failures among cases of otitis media, sinusitis and tonsillitis. The presence of normal flora that possess interfering capabilities against potential pathogens is beneficial to the host. Such flora may enhance recovery and prevent infections of the tonsils by group A beta-hemolytic streptococci. Therapeutic use of antimicrobial agents that preserve the normal flora but overcome penicillin-susceptible or -resistant pathogens may enhance recovery from upper respiratory tract infections.

Intracellular reservoir of Streptococcus pyogenes in vivo: a possible explanation for recurrent pharyngotonsillitis

Numerous theories have been presented that attempt to explain the frequent recurrences of pharyngotonsillitis caused by Streptococcus pyogenes; these recurrences occur after seemingly adequate antibiotic treatment. We previously have demonstrated that Spyogenes can survive for up to 7 days intracellularly in immortalized human respiratory epithelial cells grown in an antibiotic supplemented medium. Viable S pyogenes were externalized and established an extracellular infection, whenever the extracellular antibiotic was removed. We have investigated the presence of intracellular S pyogenes in two in vivo studies using respiratory epithelial cells collected from patients with tonsillitis and the tonsils of asymptomatic carriers. Electron microscopy and immunohistochemistry demonstrated intracellular S pyogenes in pharyngeal epithelial cells in 13 of 14 patients with tonsillitis (93%). Furthermore, intracellular S pyogenes were found in macrophage-like cells in eight (73%) and in epithelial cells in four (36%) tonsils from 11 asymptomatic S pyogenes carriers. These in vivo data strongly support the hypothesis that intracellular S pyogenes can constitute a reservoir of bacteria with the potential to cause reinfections.

Group A streptococcal tonsillopharyngitis: cost-effective diagnosis and treatment

Most patients who seek medical attention for sore throat are concerned about streptococcal tonsillopharyngitis, but fewer than 10% of adults and 30% of children actually have a streptococcal infection. Group A beta-hemolytic streptococci (GAS) are most often responsible for bacterial tonsillopharyngitis, although Neisseria gonorrhea, Arcanobacterium haemolyticum (formerly Corynebacterium haemolyticum), Chlamydia pneumoniae (TWAR agent), and Mycoplasma pneumoniae have also been suggested as possible, infrequent, sporadic pathogens. Viruses or idiopathic causes account for the remainder of sore throat complaints. Reliance on clinical impression to diagnose GAS tonsillopharyngitis is problematic; an overestimation of 80% to 95% by experienced clinicians typically occurs for adult patients. Overtreatment promotes bacterial resistance, disturbs natural microbial ecology, and may produce unnecessary side effects. Existing data suggest that rapid GAS antigen testing as an aid to clinical diagnosis can be very useful. When used appropriately, it is sensitive (79% to 88%) in detecting GAS-infected patients and is specific (90% to 96%) and cost-effective. Penicillin has been the treatment of choice for GAS tonsillopharyngitis since the 1950s; 10 days of treatment are necessary for bacterial eradication. A single IM injection of benzathine penicillin is effective and obviates compliance issues. Until the early 1970s, the bacteriologic failure rate for the treatment of GAS tonsillopharyngitis ranged from 2% to 10% and was attributed to chronic GAS carriers. Since the late 1970s, the penicillin failure rate has frequently exceeded 20% in published reports. Explanations for recurrent GAS tonsillopharyngitis include poor patient compliance; reacquisition from a family member or peer, copathogenic colonization by Staphylococcus aureus, Haemophilus influenzae, Moraxella catarrhalis, anaerobes that inactivate penicillin with beta-lactamase, or all these organisms; suppression of natural immune response by too-early administration of antibiotics; GAS tolerance to penicillin; antibiotic eradication of normal pharyngeal flora that normally act as natural host defenses; and establishment of a true carrier state. When therapy fails, milder symptoms may occur during the relapse. Several antimicrobials have demonstrated superior efficacy compared with penicillin in eradicating GAS and are administered less frequently to enhance patient compliance. In previously untreated GAS throat infections, cephalosporins produce a 5% to 22% higher bacteriologic cure rate; after a penicillin treatment failure, these differences are greater. Amoxicillin/clavulanate and the extended-spectrum macrolides clarithromycin and azithromycin may also produce enhanced bacteriologic eradication in comparison to penicillin.(ABSTRACT TRUNCATED AT 400 WORDS)