Detection and Characterization of β-Lactamase Encoding Genes in Carbapenem Non-Susceptible Gram-Negative Bacteria and Susceptibility of Isolates to Ceftazidime-Avibactam at a New York City Community Hospital

A surveillance study was undertaken to identify prominent β-lactamase encoding genes in 131 carbapenem non-susceptible gram-negative clinical isolates at a New York City community hospital. KPC carbapenemases were detected in 89% of Enterobacteriaceae as well as additional TEM, SHV, and CTX-M class A enzymes. OXA-23 and OXA-24 were the prevalent class D carbapenemases identified in Acinetobacter species. One OXA-23 in M. morganii and one OXA-48 in K. pneumoniae were also identified. Among class C β-lactamases CMY, ACT/MIR, DHA, and FOX were detected. The in vitro activity of ceftazidime-avibactam by E-test methodology was tested with minimal inhibitory concentrations (MIC) of ≤3 μg/ml for 97.8% of all Enterobacteriaceae, MIC50/90 of 16/>256 μg/ml for carbapenem non-susceptible Acinetobacter, and 3/6 μg/ml for carbapenem non-susceptible Pseudomonas aeruginosa. Periodic surveillance of isolates to characterize current and emerging β-lactamase genotypes present in local isolates may help identify outbreak situations, provide assistance to infection control and antibiotic stewardship programs, and potentially improve patient outcomes.

Origin of de novo daptomycin non susceptible enterococci

The emergence of daptomycin non-susceptible enterococci(DNSE) poses both treatment and infection control challenges.Clinicians should be vigilant that DNSE may be isolated from patients with or without(de novo DNSE) prior use of daptomycin.Recent epidemiological data suggest the presence of a community reservoir for DNSE which may be associated with environmental,foodborne and agricultural exposures.The mechanisms of nonsusceptibility to daptomycin have not been well characterized and may not parallel those for Staphylococcus aureus.The identification of daptomycin resistance genes in anaerobes,in farm animals and in an ecosystem that has been isolated for million years,suggest that the environmental reservoir for de novo DNSE may be larger than previously thought.Herein,the limited available scientific evidence regarding the possible origin of de novo DNSE is discussed.The current existing evidence is not sufficient to draw firm conclusions on the origin of DNSE.Further studies to determine the mechanisms of de novo daptomycin nonsusceptibility among enterococci are needed.

Impact of the Pneumococcal Heptavalent Conjugated Vaccine on <i>Streptococcus pneumoniae</i>Nasopharyngeal Carriage and Antimicrobial Susceptibility in Children 2-5-Year-Old in Beijing, China

Streptococcus pneumoniae is a primary cause of illness and death among children younger than 5 years in China. The heptavalent pneumococcal conjugate vaccine (PCV7) was the only conjugated vaccine (PCV) available in China from 2008 to 2013. This randomized, controlled, open-label study conducted at 46 Beijing clinics involved 3281 healthy 2-5-year-old Chinese children, randomized 1:1 to receive one dose of the S. pneumoniae heptavalent conjugated vaccine (PCV7) (n = 1643) or Haemophilus influenzae type b conjugate vaccine (Hib) (n = 1638). The main objective of this study was to investigate the impact of PCV7 against that of Hib vaccination in the nasopharyngeal S. pneumoniae colonization in healthy Chinese children. Nasopharyngeal (NP) samples for culture, serotyping and antimicrobial susceptibility testing were collected before vaccination and at Day 60 and 180 post-vaccination. A total 3281 children were enrolled in the study. Demographic characteristics were similar among both study groups: 1641 children received PCV7. Before immunization, S. pneumoniae was isolated in 338 and 360 children in the PCV7 (144 PCV7 isolates) and Hib groups (145 PCV7 isolates), respectively. At Day 180, PCV7 vaccination was more effective than Hib vaccination in reduction NP carriage (20.2% [P = 0.052]) and new acquisition (19.0% [P = 0.066]). When reductions in NP carriage and new acquisition of PCV7 VT plus 6A was analyzed, reduction in the PCV7 vaccinated group achieved statistical significance (P = 0.034 and P = 0.042 versus Hib, respectively). NP carriage of NVT increased in both groups (P = 0.305 between study groups at Day 180). PCV7 decreased NP carriage of non-susceptible VT to amoxicillin (P = 0.000), ceftriaxone (P = 0.047) and MDR (P = 0.024) versus Hib. PCV7 vaccination in Chinese children 2 to 5 years of age was more effective than vaccination with Hib in the reduction of S. pneumoniae nasopharyngeal carriage, new acquisition and non-susceptible isolates.

Prevalence of antimicrobial resistance of Streptococcus pneumoniae in Chinese children: four hospitals surveillance

Objective To investigate the nasal carriage of antibiotic-resistant pneumococci in children of < 5 years old in the following four cities, Beijing, Shanghai, Guangzhou and Xi' an.Methods A total of 647 pneumococci strains were isolated and detected. Minimal inhibition concentrations (MICs) of antibiotics were determined by E-test. Disk diffusion test was used for the measurement of antimicrobial susceptibility.Results Prevalence of penicillin non-susceptible Streptococcus pneumoniae in the four cities was 41%, with Guangzhou (60.8%) ranking first, followed by Xi' an (45%), Shanghai (37%) and Beijing (25. 9%). The majority of penicillin non-susceptibility isolates (23. 9% -53. 8%) had a low level of resistance (MIC 0. 64 -1. 5 μg/ml). The most sensitive antimicrobials in terms of percentage of susceptible organisms were amoxicillin-clavulanic acid ( 99.4%), followed by ceftriaxone (92. 1 %); cefurxime and cefaclor were slightly more sensitive than penicillin with susceptibility of 74. 8% and 77. 9%. Erythromycin, tetracycline and TMP-SMZ were highly resistant (83. 6% , 82. 1% and 76.2% respectively) . Among erythromycin resistant isolates, 100% were resistant to azithromycin, 98.6% to clarithromycin, 97.2% to roxithromycin and spiramycin, and 96.6% to clindamycin. 97.2% (141/145) were typical of the macrolides-lincosamides-streptogramons B (MLSB ) resistance phenotype, and 2. 8% (4/145) were M phenotype. The group of PRSP was with significantly higher rates of non-susceptibility for ceftriaxone (18. 4%), cefurxime (58. 6%), cefaclor (53. 4%), compared with the group of PEN-S (0. 5% , 1.8% and 0. 2% , respectively) and the rate of multi-drug resistance in the isolates of PRSP group (92. 9%) was significantly higher than that of PEN-S group (59.2%).Conclusion The rates of penicillin and multi-drug resistance among isolates of pneumococci carried nasally in are high children and the high prevalence of multi-drug resistance in the Chinese population may be becoming one of the most serious problems in this century.