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-β-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-β-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.
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.
Coccidioidomycosis is usually acquired by inhalation of spores of Coccidioides immitis and C. posadasii. The disease ranges from a self-limited acute pneumonia (Valley Fever) to a disseminated disease. We present a 44-year-old healthy male who had patchy hair loss of several months duration resembling discoid lupus. He developed a firm non-scaly red plaque on the right forehead. Initial biopsy showed spongiotic dermatitis, and he was treated with systemic steroids. He then developed forehead and periorbital cellulitis and was treated with systemic antibiotics. A second biopsy showed fungal hyphae, and he was treated with itraconazole 200mg bid for 4months beyond clinical resolution. A year later, he presented with intermittent swelling of the right forehead lesion and worsening of the scalp lesions. A forehead biopsy showed interface dermatitis and negative PAS stain for fungi. Scalp biopsy was highly suggestive of discoid lupus and he was started on plaquenil. Many months later, a third biopsy showed fungal infection, and the culture grew C. immitis. He was treated with itraconazole. Retrospectively, the patient gave a history of Valley fever 6 years back when he was in Arizona, USA.
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.
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