Bacteriologic Failure Rate Research Articles

Managing sore throat: a literature review I. Making the diagnosis

To assess the justification for the routine use of investigations in the diagnosis of bacterial causes of sore throat. The literature from 1945 to 1990 was systematically screened to identify studies that addressed diagnosis of bacterial infection and the efficacy of antibiotics in sore throat, using the key-words "pharyngitis" and "tonsillitis". Difficulties were identified with clinical methods and investigations that identify streptococcal infections. The practice of throat-swab culture--the "gold standard"--appears to have developed as a strategy to protect patients from acute rheumatic fever. However, this method may be limited in its usefulness for protection against acute rheumatic fever because: (i) in many cases in which the streptococcus is isolated from symptomatic patients there is no serological evidence of infection; (ii) there are very high asymptomatic carrier rates of the streptococcus; (iii) even after adequate treatment with penicillin there are high bacteriological failure rates; and (iv) those organisms that can be isolated from the mucosal surface are a poor representation of organisms lying deep in the tissues. Evaluation of other diagnostic techniques such as Gram's stain and rapid antigen testing, as well as decision analysis, has also been hampered by the difficulties encountered with use of this inadequate gold standard. There is little indication from the literature that any routine system of identifying bacterial causes of sore throat is helpful to the clinician.

Time kill curve analysis of vancomycin and rifampin alone and in combination against nine strains of nutritionally deficient streptococci.

Endocarditis caused by nutritionally deficient streptococci has a high bacteriologic and clinical failure rate, despite appropriate antimicrobial therapy. We investigated by time kill curve methodology nine clinical endocarditis isolates of nutritionally deficient streptococci to determine the in vitro efficacies of vancomycin and rifampin alone and in combination. The combination of vancomycin and rifampin demonstrated synergy and bactericidal activity in five of the strains. In one strain, this combination inhibited growth by greater than 2 log10 CFU/ml when compared to the growth control or either antibiotic alone, but it failed to be bactericidal. Indifference, defined as less than or equal to 2 log10 CFU per milliliter increase in killing of the combination compared to the next most active single agent, was demonstrated with the remaining three isolates. Changing the antibiotic concentrations in the time kill curve studies for these latter strains failed to demonstrate synergistic activity of the antibiotic combination. The vancomycin and rifampin combination may be a promising therapeutic modality for which in vivo correlation is indicated.

Once daily therapy for streptococcal pharyngitis with cefadroxil

To determine if a single daily dose of cefadroxil would be effective in the treatment of group A beta-hemolytic streptococcal (GABHS) pharyngitis, 196 patients with GABHS pharyngitis were randomly assigned to receive either penicillin V 250 mg three times daily or cefadroxil 30 mg/kg once daily, for 10 days. Outcome was measured by the ability to isolate GABHS from the upper respiratory tract 18 to 24 hours after the onset of therapy, the impact on the clinical course, and the bacteriologic treatment failure rate. There was no significant difference in the number of patients in the cefadroxil and penicillin V treatment groups with throat cultures positive for GABHS at the 18 to 24-hour follow-up visit (0% and 2%, respectively), and the clinical responses of the patients in the two treatment groups were similar. Of the 99 patients in the three times daily penicillin V group, six (6%) had strains of GABHS isolated on one of the follow-up cultures that were identical to the strains isolated from their initial throat cultures and were considered to have bacteriologic treatment failures. Of the 96 patients in the once daily cefadroxil group, two (2%) were considered to have bacteriologic treatment failures. A single daily dose of cefadroxil appears to be as effective in the treatment of GABHS pharyngitis in this population as penicillin V given three times daily.

468 TREATMENT (Rx) OF GROUP A STREPTOCOCCAL (GAS) PHARYNGITIS. RESULTS OF A PROSPECTIVE, RANDOMIZED STUDY OF 4 ANTIBIOTICS

Penicillin V (P), benzathine/procaine penicillin (BP), cefadroxil (C), and erythromycin estolate (EE) were used for Rx of 198 children with GAS pharyngitis. Patients ranged in age from 2-15 years and all were symptomatic when Rx was started. Rx groups were similar with regard to age, sex, weight and duration of illness before Rx. All pts improved within 24 hours of initiation of Rx. At 5 days GAS were present in the throat cultures of 3 pts (2P, 1C); the serotypes of 2 organisms were identical to those isolated from pre-Rx cultures. Four days after Rx GAS were cultured from 3(6%) P-Rx'd pts, 1(2%) C pt, 1(2%) E pt, and 2(4%) BP pts. All were serotypically identical to the pre-Rx organisms. Two (21%) of these pts were symptomatic. GAS were isolated from 19 pts at 7-21 days after Rx; 12 of 19 had new serotypes and 11(91%) of these 12 were symptomatic. Excluding pts with new infections, the bacteriologic failure rates (relapse) during the 31-day study period were: 2%(EE), 6%(C), 12%(P) and 12%(BP). Eleven of 16(69%) children with relapse were asymptomatic at the time of recurrence. There were no significant differences in the rates of serologic conversion between symptomatic (82%) and asymptomatic (54%) children or between those with reinfection (77%) and those with relapse (63%). Antibiotic resistance of GAS, presence of penicillinase-producing staphylococci and lack of compliance were not related to relapse. These four antibiotics were equally effective in Rx of GAS pharyngitis.

Changes and Changing Concepts in the Biology of Group A Streptococci and in the Epidemiology of Streptococcal Infections

Concepts of the cellular structure of group A streptococci have been modified by the recognition of surface fimbriae and by problems with the older view of a layered arrangement of cell wall components. Evidence of genetic drift of serologic types and of some increase in the prevalence of erythromycin-resistant strains has appeared. A curiois bimodal age distribution for streptococcal pharyngitis and an increase in the prevalence of non-group A strains has been detected. Despite repeated challenges, the value of throat cultures for confirming the possibility of streptococcal pharyngitis remains firmly established; throat cultures are superior to saliva cultures, which more frequently detect non-group A streptococci. Difficulties in detecting subclinical steptococcal infections and in defining streptococcal infection in children in endemic situations (particularly in separating true streptococcal infection from carriage of streptococci in individuals whose illness is due to some other agent) continue to present problems to clinicians and epidemiologists. The value of school culture surveys and of treatment of asymptomatic family contacts of cases remains uncertain. A 20% bacteriologic failure rate has been reported after intramuscular treatment with benzathine penicillin, but no in vitro evidence of resistance to penicillin has appeared. No adequate explanations are available for the decline in the problem of rheumatic fever in industrialized countries, for its increased recognition in tropical countries, for the failure of rheumatic fever to occur after streptococcal pyoderma, or for the emergence of group B Streptococcus as a predominant bacterial pathogen in newborn infants.

Double-blind treatment study of shigellosis comparing ampicillin, sulfadiazine, and placebo

A double-blind treatment study comparing ampicillin, sulfadiazine, and placebo was performed in 52 infants and children hospitalized for shigellosis. Bacteriological failure rates in patients treated with placebo and sulfadiazine were 75 per cent and 39 per cent, respectively, compared with 6 per cent in ampicillin-treated patients. Clinical failure occurred in 56 per cent of patients treated with placebo, 39 per cent in sulfadiazine-treated patients and in none of the patients who received ampicillin. Ampicillin is a safe and highly effective drug for the treatment of shigellosis.