Treatment failure in streptococcal pharyngotonsillitis. An attempt to identify penicillin tolerant Streptococcus pyogenes

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 Group A Streptococcal Carrier State Reviewed: Still an Enigma

Despite the common nature of group A streptococcal (GAS) infections, the carrier state of this organism is not well understood. In this article, we review the historical and recent research on the definition, epidemiology, and pathogenesis of the GAS carrier state. In addition, we outline trials of antimicrobial agents in the eradication of the carrier state and discuss indications for providing treatment to patients in the clinical setting.

New antimicrobial cystatin C-based peptide active against gram-positive bacterial pathogens, including methicillin-resistant Staphylococcus aureus and multiresistant coagulase-negative staphylococci

We describe the synthesis and antibacterial properties of a novel antimicrobial peptidyl derivative, (2S)-2-(Nalpha-benzyloxycarbonyl-arginyl-leucylamido-1-[(E)-cinnamoylamido]-3-methylbutane, structurally based upon the inhibitory centre of the human cysteine protease inhibitor, cystatin C. The derivative, here called Cystapep 1, displayed antibacterial activity against several clinically important gram-positive bacteria. It displayed minimal inhibitory and bactericidal concentrations of about 16 microg/ml for both Staphylococcus aureus and Streptococcus pyogenes. In radial agar diffusion assays, groups A, B, C and G streptococci as well as staphylococci were generally susceptible to the action of Cystapep 1, whereas pneumococci and enterococci were less susceptible. No activity against gram-negative bacteria was observed. Cystapep 1 also showed high activity against methicillin-resistant S. aureus (MRSA) and multiantibiotic-resistant coagulase-negative staphylococci (CNS), suggesting that its mechanism of action differs from those of most currently used antibiotics.

Penicillin V, loracarbef and clindamycin in tonsillar surface fluid during acute group A streptococcal pharyngotonsillitis

A previously healthy 37-y-old male presented with community-acquired pneumonia and extensive upper limb deep vein thrombosis. The diagnosis of Legionella pneumonia was made based on a positive direct immunofluorescence of the bronchial wash. An extensive investigation for hypercoagulable states was negative. The possible association between Legionella infection and deep vein thrombosis is highlighted.

Antimicrobial susceptibility patterns and genomic diversity in strains of Streptococcus pyogenes isolated in 1978-1997 in different Brazilian cities

Penicillin has been the antimicrobial of choice for the treatment of Streptococcus pyogenes infections for almost six decades. Although penicillin-resistant isolates have not been described to date, clinical failures have been reported after treatment with beta-lactams. In this study, we analysed the antimicrobial susceptibility and genetic diversity of S. pyogenes isolates obtained from healthy carriers or patients in different cities in the south and south east of Brazil. The MICs were determined for penicillin and seven other antimicrobials. Penicillin tolerance was also investigated. Genetic diversity was analysed by PFGE after SmaI fragmentation of the genomic DNA. All 211 isolates tested were susceptible to penicillin (MIC 0.0025-0.02 mg l(-1)). Four isolates were moderately penicillin-tolerant (MBC/MIC = 16 mg l(-1)). Most of the other drugs tested were very active against the strains examined, except for tetracycline, to which 50 % of strains were resistant. We also found extensive genetic diversity, in that 60 different patterns were recognized in the 96 strains studied. Indeed, we found no correlation between tetracycline resistance and clonality. Despite this diversity, some PFGE patterns persisted for up to 18 years and specific clone types were spread over different geographical locations

Penicillin treatment failure in group A streptococcal tonsillopharyngitis: no genetic difference found between strains isolated from failures and nonfailures

Despite penicillin (pcV) treatment, tonsillopharyngitis caused by group A streptococci (GAS) is associated with bacterial failure rates as high as 25%. The reason for this rate of failure is not fully understood. One explanation might be that certain DNA profiles of GAS strains are responsible for treatment failures. Using arbitrarily primed polymerase chain reaction (AP-PCR), we compared the DNA profiles of GAS strains from 4 patients with several treatment failures following pcV treatment of tonsillopharyngitis with the profiles of strains of the same T type from patients who were clinically and bacteriologically cured after a single course of pcV. The isolates were obtained during the same time period and from the same geographic area. Thirty-seven strains of T types 4, 12, and R28 were investigated. Eleven different DNA profiles could be detected with the AP-PCR technique. Five DNA profiles were identified as T type 12, 3 as T type 4, and 3 as T type R28. The DNA profiles of the strains from the 4 patients with several treatment failures differed, but all isolates from each one of these patients exhibited the same or a very similar profile. The DNA profiles of the failure strains were also represented in nonfailure strains. Treatment failure in these 4 patients therefore seems to be due to insufficient eradication of GAS, rather than to reinfection with a new strain. The finding that the same DNA profile can be present in both failure and nonfailure strains suggests that the treatment failure may be to some extent host-related and not only due to bacterial factors.

Unusual occurrence of M type 77, antibiotic-resistant group A streptococci in southern Sweden

For many years group A streptococci of T type 28 (T28) have been common in southern Sweden; however, since 1995 resistance to both macrolide-lincosamide-streptogramin B (MLS) antibiotics and tetracycline was observed among T28 isolates, which prompted the present studies on clonal relatedness of antibiotic-resistant T28 strains. By extended T typing, 95 of 100 examined tetracycline-resistant strains showed the combination T9-T13-T28; of these, 94 belonged to M type 77 (M77) and one belonged to M73. Three strains were T28-M28 and two were T28-M nontypeable. The serological M77 was confirmed by PCR capture enzyme-linked immunosorbent assay, emm amplicon restriction profiling, and emm sequence typing. Fifty strains were examined for superantigen genes: speA was detected in three blood isolates only, whereas all isolates harbored speB, and only two of the strains were negative for speC. Eighty-nine of the 100 strains were also macrolide resistant, of which 59 were inducibly MLS resistant (IR) and 21 were constitutively MLS resistant (CR), 6 were noninducibly resistant (NI), and 3 had novel subphenotypes recently reported by our group. Resistance genes were determined by PCR and hybridization methods. Eighty-four of the 100 strains harbored tetM. ermB was detected in all CR and IR strains, and mefA was found in all NI strains; both ermB and mefA were identified in two strains with novel subphenotypes. Pulsed-field gel electrophoresis showed that these antibiotic-resistant M77 strains belonged to at least five different clones.

Penicillin failure in streptococcal tonsillopharyngitis: causes and remedies

Penicillin administered for 10 days has been the treatment of choice for group A beta-hemolytic streptococcal tonsillopharyngitis since the 1950s. The bacteriologic failure rate of 10 days of penicillin therapy ranged from approximately 2 to 10% until the early 1970s. Beginning in the late 1970s bacteriologic and clinical failure rates with penicillin therapy began to increase steadily over time and are now reported to be approximately 30%. The primary cause of penicillin treatment failure in streptococcal tonsillopharyngitis may be lack of compliance with the 10-day therapeutic regimen. Other causes of penicillin treatment failure include reexposure to Streptococcus-infected family members or peers; copathogenicity, in which bacteria susceptible to a class of drugs are protected by other, colocalized bacterial strains that lack the same susceptibility; antibiotic-associated eradication of normal protective pharyngeal flora; and penicillin tolerance, whereby streptococcal bacteria repeatedly or continuously exposed to sublethal concentrations of antibiotic become increasingly resistant to eradication. Although 10 days of penicillin therapy is effective in the management of tonsillopharyngitis for many patients, multiple factors may, singly or together, cause treatment failure. A number of antibiotics, particularly the cephalosporins, have been demonstrated to be superior to penicillin at eradicating group A beta-hemolytic Streptococcus, and several are effective when administered for 4 to 5 days.

CONCLUSIONS

Ten days of penicillin therapy may not be the best therapeutic choice for all pediatric patients. Other antibiotics, shortened courses of the cephalosporins in particular, may be preferable in some cases.

High rate of tetracycline resistance in Streptococcus pyogenes in Iran: an epidemiological study

Streptococcus pyogenes, a major human pathogen, is still considered susceptible to beta-lactams, but for other relevant antibiotics, highly variable resistance rates have been reported. Since no data were available from Iran, we tested 1,335 throat isolates from two different regions of the country for their antibiotic susceptibilities and, for comparison, a collection of 80 strains isolated from 1989 to 1991. Erythromycin resistance was uncommon (0.6%), whereas an overall high rate of tetracycline resistance was found, increasing between 1989-1991 and 1995-1997 from 23 to 42%. The tetracycline-resistant strains belonged to more than 10 different T types, the majority being types 4, 11, and B3264. By conventional M typing of 406 tetracycline-resistant isolates, more than 20 different M types were found. Approximately 50% of the strains were nontypeable by T agglutination as well as serological M typing; however, by genotyping by a combined PCR-capture-enzyme-linked immunosorbent assay, many of these strains were successfully emm typed. We conclude that the high rate of tetracycline resistance among Iranian S. pyogenes isolates is due to multiclonal dissemination of resistance within the streptococcal population rather than epidemic spread of single clones.

[Streptococcus pyogenes: in vitro susceptibility and role of beta-lactamase producing bacteria in the persistence of streptococcal pharyngotonsillitis]

OBJECTIVE

To assess the frequency of association between Streptococcus pyogenes and beta-lactamase-producing-bacteria in the pharyngotonsillitis and the evaluate the in vitro susceptibility.

DESIGN

Prospective, descriptive, transverse study.

SETTING

The present study was carried out in the Health Center Dr. José Castro Villagrana, in Tlalpan, México, D.F., from Juanary, 1996 to February 1999.

PARTICIPANTS

In three hundred and ninety four patients with pharyngotonsillitis diagnosis we isolated the same number of Streptococcus pyogenes, and possible beta-lactamase-producing-bacteria.

RESULTS

In 180 patients (45.7%) we isolated at least one possible beta-lactamase-producing-bacteria. Of these, in 138 patients (35%) were confirmed the enzyme presence. In total, we isolated 218 possible beta-lactamase-producing bacteria, and 152 (69.7%) were beta-lactamase positive. We found no significant change in the in vitro susceptibility of group A Streptococcus to penicillin, but erythromycin resistance is relatively common, approximately 10% in this study.

CONCLUSIONS

Streptococcus pyogenes was uniformly susceptible to all penicillins and cephalosporins in vitro. Erythromycin treatment should not be promoted as first-line therapy because the consequent increase of bacterial resistance could create difficulty in treating penicillin-allergic patients. Because of the poor activity of trimetoprimsulfametoxazol, this drug no longer can be considered the drug of choice for the management of group A Streptococcal infections.

Amoxycillin tolerance in Helicobacter pylori

Resistance to amoxycillin in Helicobacter pylori has only recently been reported. To demonstrate the existence of resistance, and to test for the presence of tolerance, 17 amoxycillin-resistant strains of H. pylori, first isolated in Sardinia (Italy) and the USA, were studied. Four amoxycillin-sensitive strains were used as controls. Primary isolates of all test strains exhibited amoxycillin resistance; beta-lactamase activity was not detected. Amoxycillin resistance was lost after storage of strains at -80 degrees C but could be rescued by plating these strains on to amoxycillin gradient plates. MICs and MBCs from rescued isolates ranged from 0.5 to 32 mg/L and from 32 to > 1024 mg/L, respectively. MBC/MIC ratios > or = 32 are characteristic of antibiotic tolerance. The ratios of MBC/MIC of amoxycillin ranged from 32 to > 1024 for the test strains, indicating that these strains were tolerant to the antibiotic. Amoxycillin resistance does occur in H. pylori. Amoxycillin susceptibility testing of H. pylori isolates in patients who fail therapy should include determination of the MBC to detect tolerance.