Azithromycin (AZM) has been recommended by the American Academy of Pediatrics for the treatment of shigellosis in children. In this study, 502 Shigella species isolated between 2004 and 2014 were tested for AZM epidemiological cutoff values (ECV) by disk diffusion. AZM MICs and the presence of the macrolide resistance genes [erm(A), erm(B), erm(C), ere(A), ere(B), mph(A), mph(B), mph(D), mef(A), and msr(A)] were determined for all 56 (11.1%) isolates with an AZM disk diffusion zone diameter of Յ15 mm. The distribution of AZM ECV MICs was also determined for 186 Shigella isolates with a disk zone diameter of Ն16 mm. Finally, pulsed-field gel electrophoresis (PFGE) was performed on 15 Shigella flexneri isolates with an AZM disk zone diameter of Ͻ16 mm from different years and geographic locations. Serotyping the 502 Shigella species isolates revealed that 373 (74%) were S. sonnei, 119 (24%) were S. flexneri, and 10 (2%) were S. boydii. Of the 119 Shigella flexneri isolates, 48 (42%) isolates had an AZM disk diffusion zone diameter of Յ15 mm and a MIC of Ն16 g/ml. With the exception of one isolate, all were positive for the macrolide resistance gene mph(A). S. flexneri PFGE showed four distinct patterns, with patterns I and II presenting with 92.3% genetic similarity. On the other hand, 2 (0.5%) of the 373 S. sonnei isolates had the AZM non-wild-type (NWT) ECV phenotype (those with acquired or mutational resistance), as the AZM MICs were Ն32 g/ml and the isolates were positive for the mph(A) gene. Overall, our S. flexneri results are in concordance with the CLSI AZM ECV, but isolates with an AZM disk diffusion zone diameter between 14 and 15 mm should be carefully evaluated, as the S. flexneri AZM MIC for NWT isolates may need adjustment to 32 g/ml. Our data on S. sonnei support that the AZM NWT ECV should be 11 mm for the disk diffusion zone diameter and Ն32 g/ml for the MICs.

Infections of Streptococcus pneumoniae in children can be prevented by vaccination; left untreated, they cause high morbidity and fatalities. This study aimed at determining the nasopharyngeal carrier rates, serotype distribution and antimicrobial resistance patterns of S. pneumoniae in healthy Palestinian children under age two prior to the full introduction of the pneumococcal 7-valent conjugate vaccine (PCV7), which was originally introduced into Palestine in a pilot trial in September, 2010. In a cross sectional study, nasopharyngeal specimens were collected from 397 healthy children from different Palestinian districts between the beginning of November 2012 to the end of January 2013. Samples were inoculated into blood agar and suspected colonies were examined by amplifying the pneumococcal-specific autolysin gene using a real-time PCR. Serotypes were identified by a PCR that incorporated different sets of specific primers. Antimicrobial susceptibility was measured by disk diffusion and MIC methods. The resulting carrier rate of Streptococcus pneumoniae was 55.7% (221/397). The main serotypes were PCV7 serotypes 19F (12.2%), 23F (9.0%), 6B (8.6%) and 14 (4%) and PCV13 serotypes 6A (13.6%) and 19A (4.1%). Notably, serotype 6A, not included in the pilot trial (PCV7) vaccine, was the most prevalent. Resistance to more than two drugs was observed for bacteria from 34.1% of the children (72/211) while 22.3% (47/211) carried bacteria were susceptible to all tested antibiotics. All the isolates were sensitive to cefotaxime and vancomycin.Any or all of these might impinge on the type and efficacy of the pneumococcal conjugate vaccines and antibiotics to be used for prevention and treatment of pneumococcal disease in the country.

This work was presented as a master's thesis and defended by author ABO under the supervision of author SAB at Al-Quds University in collaboration with author MA who provided several bacterial strains and helped in their morphological and cultural identification. Author IW suggested several ideas on media formulation. Author IS performed the real time PCR using his resources. All authors read and approved the final manuscript.