[Significance of normal oropharyngeal flora in the development of streptococcal pharyngitis and outcome of penicillin therapy]. / Znacaj normalne orofaringealne flore u nastanku streptokoknog faringitisa i ishodu terapije penicilinom.

Pharyngitis is one of the most frequent diseases in children. The most important of the bacterial infections is due to Streptococcus pyogenes. For many years, penicillin is considered to be the drug of choice for streptococcal pharyngitis, although failure rates of up to 20% have been reported. One of possible explanations for penicillin treatment failure is presence of other species of bacteria in the normal oropharyngeal flora that can interfere with colonization and growth of Streptococcus pyogenes and influence the development of pharyngitis. A wide variety of microorganisms, including alpha-haemolytic streptococci and anaerobic bacteria, are present within the oropharynx (table 1). The strain of alpha-haemolytic streptococci is in interference with Streptococcus pyogenes. By producing bacteriocins, they inhibit colonization and growth of Streptococcus pyogenes and assist in its eradication. Anaerobic bacteria may play a direct or indirect role in development of pharyngitis. They may be directly responsible for specific forms of pharyngitis or contribute indirectly with possibility of synergy between them and Streptococcus pyogenes. Beta-lactamase-producing aerobic and anaerobic organisms may contribute to penicillin treatment failure. By producing beta-lactamase within the tonsillar tissue, they destroy penicillin and protect streptococci from the antibacterial effect of penicillin. Pharyngeal bacterial flora may vary according to the state of the patient (Figure 1). During an acute infection and in the cases of treatment failure and recurrent pharyngitis the number of alpha-haemolytic streptococci declines, while there is an increase in the number of anaerobic and beta-lactamase-producing organisms. After successful treatment the number and type of bacteria is similar to those found within normal tissue. Knowing the distribution and changes in pharyngeal bacterial flora is important for choosing the optimal drug for treatment of streptococcal pharyngitis. Although penicillin reduces the number of interfering beta-haemolytic streptococci, because of its advantages, if remains the drug of choice for the treatment of streptococcal pharyngitis. In cases of treatment failure and recurrent infections cephalosporins and macrolides may be a useful alternative to penicillin because they possess relatively poor activity against alpha-haemolytic streptococci, resistance to beta-lactamase and because of better penetration into tonsilar tissue.

[Sensitivity of Streptococcus pneumoniae to antimicrobial drugs]. / Osetljivost sojeva streptokokus pneumonije na antimikrobne lekove.

INTRODUCTION: Streptococcus pneumoniae is the leading cause of community acquired pneumonia and a frequent cause of otitis media, sinusitis and meningitis. Although most pneumococci remain susceptible to penicillin, relatively less susceptible and resistant strains have been recognized with increasing frequency throughout the world (1). The aim of this study was to determine whether and to what degree pneumococci isolated in our laboratory were resistant to penicillin and other frequently used antimicrobial agents. MATERIAL AND METHODS: During the period from 1991 to 1995 1139 Streptococcus pneumoniae strains isolated from patients with different pneumococcal infections were tested for their susceptibility to antimicrobial agents at the Department of Bacteriology and Parasitology of the Institute of Public Health in Novi Sad. Antimicrobial agents tested included: penicillin, ampicillin, cephalexin, erythromycin, sulfamethoxazole-trimethoprim and clindamycin. Susceptibility test was performed by using Kirby-Bauer disc diffusion technique on Mueller-Hinton agar supplemented with 5% defibrinated bovine blood (5). RESULTS: Susceptibility of Streptococcus pneumoniae to seven antimicrobial agents used in the study is shown in Table 2. There was a resistance to all antimicrobial agents tested. It was the lowest to erythromycin (1.6%) and the highest to sulfamethoxazole+ trimethoprim (67.3%). The rate of resistance of penicillin was 3.3%. In Table 3 and 4 we can also see that the lowest resistance was to erythromycin, and the highest to sulfamethoxazole+trimethoprim, both for isolates from nose and other sources. Strains of Streptococcus pneumoniae isolated from nasal swabs were more susceptible to penicillin than those isolated from blood, sputum and cerebrospinal fluid. DISCUSSION: For many years penicillin has been the mainstay of therapy for pneumococcal diseases. Clinical resistance to penicillin was first reported in 1960's. Since this early reported, penicillin resistance has been encountered with increasing frequency in strains of Streptococcus pneumoniae from around the world. In our study resistance to penicillin was low (3.3%). This is in accordance with the authors from Italy, Great Britain, USA and Germany (7, 8, 9, 10). Much higher prevalence of resistant pneumococci we found in the reports from Spain, France and Hungary (13, 14, 15, 17). Many of these strains have been resistant to multiple drugs and have been isolated from patients with invasive infections (meningitis, pneumonia, bacteremia). Percentage of penicillin resistant pneumococci isolated from blood, sputum and cerebrospinal fluid in our study was relatively low (7.7%), but it was higher than the percentage of resistant isolates from nasal swabs (2.0%). These findings are in accordance with other reports (20, 21). CONCLUSION: The increasing number of Streptococcus pneumoniae isolates resistant to penicillin and other antimicrobial agents indicates the need to perform susceptibility testing for every isolated strain in order to avoid possible therapeutic failure.

[Evaluation of the Respiralex test for rapid isolation of Streptococcus pyogenes directly from throat swabs]. / Evaluacija Respiralex testa za brzo dokazivanje Streptococcus pyogenesa direktno u brisu guse.

Results obtained by fast Respiraplex test were compared with findings of classical method of cultivation in order to assess possibilities of this test in isolation of Streptococcus pyogenes directly in the throat swab. The sensitivity of the fast test was 79.4%; specificity 100%. On the basis of gathered results, the following can be concluded: the fast test cannot completely substitute the classic method of cultivation although high specificity occurs, because of low sensitivity especially in patients with small number of colonies in the culture.