TRENDS IN ANTIBIOTIC SUSCEPTIBILITY PATTERNS OF STREPTOCOCCUS PNEUMONIAE AND HAEMOPHILUS INFLUENZAE ISOLATES: FOUR YEARS FOLLOW UP

This study was aimed to follow up the antibiotic resistance trends in Streptococcus pneumoniae and Haemophilus influenzae isolated from clinical specimens between 2003-2006 at Marmara University Hospital, Istanbul, Turkey Antibiotic susceptibilities were performed by disk diffusion method, and penicillin susceptibility was determined by E-test (AB Biodisk, Sweden) Results were evaluated by CLSI standards During this period a total of 258 S pneumoniae and 548 H influenzae were isolated in our laboratory According to the 2006 CLSI penicillin breakpoints, overall resistance of S pneumoniae isolates to penicillin was 39 9% and intermediate and high level penicillin resistance rates were 30 2% and 9 7%, respectively The rates of high level penicillin resistant pneumococci by years were 11 1% in 2003, 10.9% in 2004, 6% in 2005, 12 1% in 2006 and except for 2005 no significant change in resistance rates was detected However, according to the 2008 CLSI penicillin breakpoints, resistance was found to be 3.5%, intermediate and high level penicillin resistance being 3.1% and 0.4%, respectively. While penicillin resistance rates by years were as 4 4% in 2003, 5.5% in 2004, 0% in 2005 and 4 4% in 2006, high level penicillin resistance was detected only in 2003 as 2 2%. Resistance rates of chloramphenicol, erythromycin, tetracyline and trimethoprim-sulphametoxazole (TMP-SMX) were detected as 10.1%, 19%, 26.8% and 49 2%, respectively while erythromycin, tetracycline and TMP-SMX multi-drug resistance was detected in 12 4% of the isolates. No resistance was detected to vancomycin. Beta-lactamase production rate in H influenzae isolates was 3 3%, being 1 6% in 2003 with a raise up to 4% in 2006 No beta-lactamase negative ampicillin-resistant isolate was detected. Although chloramphenicol and cefaclor resistance were in low levels (2 2% and 0 7%, respectively), TMP-SMX resistance was detected as 25.5% TMP-SMX resistance was two fold more in beta-lactamase producers compared with the non-producers, whereas chloramphenicol resistance revealed a significant increase in beta-lactamase producers (1% versus 44 5%) In conclusion, doubling of beta-lactamase production rate in H.influenzae within years indicates the importance of continuous follow-up of antibiotic resistance in specific pathogens The evaluation of penicillin results obtained for pneumococci according to modified 2008 CLSI criteria revealed that penicillin can still be used effectively in the treatment of pneumococcal respiratory tract infections. Continuous active surveillance of resistance rates provides important data for the determination of the empirical therapy protocols for S pneumoniae and H influenzae infections

Delftia acidovorans: A rare pathogen in immunocompetent and immunocompromised patients

Delftia acidovorans is an aerobic, nonfermenting Gram-negative bacillus. It is usually a nonpathogenic environmental organism and is rarely clinically significant. Although D acidovorans infection most commonly occurs in hospitalized or immunocompromised patients, there are also several reports documenting the infection in immunocompetent patients. The present article describes a B cell lymphoblastic leukemia patient with D acidovorans pneumonia who was successfully treated with antibiotic therapy. The present report indicates that unusual pathogens may be clinically significant in both immunocompromised and immunocompetent patients. D acidovorans is often resistant to aminoglycosides; therefore, rapid detection of this microorganism is important

Antimicrobial Susceptibility Profiles of Prevotella Species Determined by Gradient Test Method in Two Centers in Istanbul

Prevotella species, being members of the human microbiota, are obligate anaerobic gram-negative bacteria. These organisms may cause opportunistic infections, including specific oral infections, local or systemic infections. A significant increase of resistance to some antimicrobials has been detected among Prevotella species. The frequency of resistance vary among isolates from different infection sources and between geographic locations. The knowledge about the antimicrobial susceptibility patterns of different Prevotella species is limited in Turkey. Providing the antimicrobial susceptibility data of these bacteria is very important for effective empirical treatment. In this study, we aimed to determine susceptibility data for 12 antimicrobial agents against Prevotella strains originating from human infections, collected in two centers in Turkey. A total of 118 Prevotella strains, isolated from different clinical samples in Marmara University Faculty of Medicine Medical Microbiology and Istanbul University Faculty of Dentistry Oral Microbiology Laboratories between January 2014-December 2017, were tested. Organisms were identified by using MALDI-TOF MS and by 16S rRNA gene sequencing. Minimal inhibitor concentrations of ampicillin, ampicillin-sulbactam, piperacillin-tazobactam, cefoxitin, meropenem, imipenem, clindamycin, tetracycline, tigecycline, moxifloxacin and metronidazole were determined using gradiyent test methodology (E-test; bioMerieux, France) and the European Committee on Antimicrobial Susceptibility Testing, Clinical and Laboratory Standards Institute and Food and Drug Administration guidelines were used for interpretation. Thirteen different Prevotella species were identified, Prevotella bivia and Prevotella nigrescens were the most prevalent species (n=21) followed by Prevotella buccae (n=19). All Prevotella strains were susceptible to piperacillin-tazobactam, cefoxitin, meropenem, imipenem and tigecycline. A total of 2 (1.7%) isolates were resistant to metronidazole and 1 (0.8%) isolate was intermediately resistant to ampicillin/sulbactam. The frequency of resistant isolates against ampicillin, clindamycin, tetracycline and moxifloxacin were 57.6%, 36.4%, 18% and 16.3%, respectively. In conclusion, piperacillin/tazobactam, cefoxitin, and tigecycline displayed high in vitro activity against Prevotella spp. and they all remained good candidates for empiric therapy. Imipenem and meropenem were also found to be very active, but the usage of carbapenems should be reserved for serious mixed infections, potentially accompanied by other resistant organisms. Intermediate resistance to ampicillin-sulbactam and the resistance against metronidazole emphasized the need of periodic monitoring of their susceptibility patterns. The high rates of non-susceptibility to ampicillin, clindamycin, tetracycline and moxifloxacin indicated that these antimicrobials should not be used for treatment of infections without prior antimicrobial susceptibility testing