Genotypes and prevalence of carbapenemase-producing Enterobacteriaceae and Pseudomonas aeruginosa in a hospital in Saudi Arabia.

BACKGROUND: The molecular epidemiology of resistance of carbapenem-resistant Enterobacteriaceae (CRE) and Pseudomonas aeruginosa are important in the study of multidrug-resistant bacteria. We evaluate the prevalence of the different mechanisms of CRE in a hospital in Saudi Arabia. METHODS: Carbapenem non-susceptible isolates of Enterobacteriaceae and Pseudomonas aeruginosa were tested by real-time PCR for the detection of genes responsible for beta-lactam resistance. RESULTS: There were a total of 200 isolates with carbapenem non-susceptibility and these were Klebsiella pneumoniae (n=96, 48%), Escherichia coli (n=51, 25.5%) and Pseudomonas aeruginosa (n=45, 22.5%). The detected carbapenemases were oxacillinase-48 (OXA-48) (n=83, 41.5%), New Delhi metallo-ß-lactamase (NDM) (n=19, 2.5%) and both NDM and OXA-48 (n=5, 2.5%). The other carbapenemases were imipenemase (n=1, 0.5%), Verona integrin encoded metallo-ß-lactamase (n=6, 3%) and Klebsiella pneumoniae carbapenemase (n=1, 0.5%), but none were detected in 86 isolates (43%). CONCLUSION: The most common carbapenemases were OXA-48 and a significant percentage had no detectable genes. These data will help in the selection of new antimicrobial therapies.

Antimicrobial resistance of gram-negative bacteria: A six-year longitudinal study in a hospital in Saudi Arabia.

INTRODUCTION: Increasing prevalence of antimicrobial resistance is a major concern especially in light of lack of new antimicrobial agents. Here, we present antibiotic resistance pattern of gram-negative bacteria (GNB) over six years (2013-2018) in a hospital in Saudi Arabia. MATERIALS AND METHODS: The study included a report of the cumulative antibiogram of GNB. Interpretation of the antibacterial susceptibility tests was based on the Clinical and Laboratory Standards Institute guidelines and VITEK® 2 system. RESULTS: There was a total of 32,890 GNB isolates and the most common were: Escherichia coli (69.8%), Klebsiella pneumoniae (17.2%) and Pseudomonas aeruginosa (12.8%). Antimicrobial susceptibility of P. aeruginosa and E. coli did not change overtime, however, susceptibility to ceftazidime decreased from 92% to 85% in P. aeuroginosa. Yearly antimicrobial susceptibility did not change significantly overtime for K. pneumoniae. ESBL isolates among K. peumoniae and E. coli was about 26% and 20%, respectively (p=0.0068). For ESBL E. coli, the least effective antibiotics were ciprofloxacin (26%) and trimethoprim-sulfamethoxazole (34%). For ESBL K. pneumoniae, gentamicin, ciprofloxacin, trimethoprim-sulfamethoxazole, and nitrofurantoin had poor activity. For K. pneumoniae, both ciprofloxacin (90%) and trimethoprim-sulfamethoxazole (86%) had better coverage than for E. coli. K. pneumoniae showed less susceptibility to nitrofurantoin than E. coli (20% vs. 92%). CONCLUSION: Antibiotic resistance among P. aeruginosa and E. coli did not change overtime (2013-2018) and the rate of ESBL-producing E. coli and K. pneumoniae was high. Thus, continued surveillance is needed.

Modified use of real-time PCR detection of group B Streptococcus in pregnancy.

The CDC recommends antenatal screening of vaginal/rectal samples for Streptococcus agalactiae at 35-37 weeks' gestation, with intra-partum antibiotic prophylaxis for positive cases. We tested a modified use of the Cepheid Xpert GBS real-time PCR kit on enrichment cultures from 554 vaginal/rectal swabs compared to the current subculturing gold standard method. Swabs were inoculated on polymyxin nalidixic acid agar plates, and Todd-Hewitt enrichment broth cultures were examined daily for growth. Todd-Hewitt broth culture was also used for Xpert GBS. There was 92.06 % agreement between the subculture and PCR methods. Sensitivity of Xpert GBS was 100 %, specificity was 89.40 %, positive predictive value was 75.96 % and negative predictive value was 100 %. Colonization incidence was higher with younger (≤24 years) or older (≥35 years) maternal age. Modified use of the Cepheid Xpert GBS would assist rapid diagnosis of S. agalactiae colonization and facilitate timely and appropriate assignment to intra-partum antibiotic prophylaxis.

Epidemiology and detection of acinetobacter using conventional culture and in-house developed PCR based methods.

Active surveillance cultures for multidrug-resistant (MDR) gram-negative bacteria is one strategy to control outbreaks. The objectives of the study are to evaluate the prevalence of Acinetobacter colonization and to compare conventional culture and in-house developed PCR based method. Swabs were collected from patients transferred from another organization or were admitted to the intensive care units. Swabs were cultured by conventional method and were tested using in-house LightCycler® 2.0 real-time PCR method. Of 449 tested samples, the majority came from cardiac step down unit (188, 42%), male medical floor (80; 18%), and coronary care unit (66; 13.4%). Of the total specimens, 14 (3%) were positive by PCR and 12 (2.6%) were positive by routine cultures. The positivity rates among wounds, respiratory, perineal, and nasal samples were 3.2%, 9.7%, 4.6% and 0.8% respectively. Two positive samples by PCR were negative by routine culture. The overall concordance rate was 99.5% and the positive concordance rate was 85.7%. The current study revealed a low prevalence of MDR Acinetobacter among the studied population. The LightCycler® 2.0 PCR produced comparable positive results to routine cultures.