METHODOLOGY: One hundred and twenty clinical isolates of S. pneumoniae were obtained from patients of University Malaya Medical Centre (UMMC). The strains were screened using a multiplex real-time PCR method for the presence of alterations in the genes encoding the penicillin binding proteins: pbp2b, macrolide resistance determinant ermB and the pneumolysin gene, ply. Dual-labelled Taqman probes were used in the real-time detection method comprising three different genes labeled with individual fluorophores at different wavelengths. One hundred and twenty isolates from bacterial cultures and isolates directly from blood cultures samples were analyzed using this assay.
RESULTS: A multiplex PCR comprising the antibiotic resistance genes, ermB and and pneumolysin gene (ply), a S. pneumoniae species specific gene, was developed to characterize strains of S. pneumoniae. Out of the 120 pneumococcal isolates, 58 strains were categorized as Penicillin Sensitive Streptococcus pneumoniae (PSSP), 36 as Penicillin Intermediate Streptococcus pneumoniae (PISP) and 26 as Penicillin Resistant Streptococcus pneumoniae (PRSP). All the 58 PSSP strains harboured the pbp2b gene while the 36 PISP and 26 PRSP strains did not harbour this gene, thus suggesting reduced susceptibility to penicillin. Resistance to erythromycin was observed in 47 of the pneumococcal strains while 15 and 58 were intermediate and sensitive to this drug respectively. Susceptibility testing to other beta-lactams (CTX and CRO) also showed reduced susceptibility among the strains within the PISP and PRSP groups but most PSSP strains were sensitive to other antibiotics.
CONCLUSION: The characterization of pneumococcal isolates for penicillin and erythromycin resistance genes could be useful to predict the susceptibility of these isolates to other antibiotics, especially beta-lactams drugs. We have developed an assay with a shorter turnaround time to determine the species and resistance profile of Streptococcus pneumoniae with respect to penicillin and macrolides using the Real Time PCR format with fluorescent labeled Taqman probes, hence facilitating earlier and more definitive antimicrobial therapy which may lead to better patient management.
MATERIALS AND METHODS: Febrile neutropenic patients treated between January 1996 and December 1997 at the pediatric oncology unit of University Hospital, Kuala Lumpur, were prospectively studied. Empirical antibiotic therapy consisted of ceftazidime and amikacin. Those who developed K. pneumoniae bacteremia were identified, and clinical features analyzed. Ceftazidime-resistance was documented via disk-diffusion testing. Production of extended-spectrum beta-lactamase (ESBL) was inferred on the basis of synergy between ceftazidime and amoxicillin-clavulanic acid. The different features between the two groups and variables associated with the development of CRKP bacteremia were analyzed using chi-square and t-tests and calculation of odds ratios. A multivariate analysis was used to identify independent factors for CRKP development.
RESULTS: Ceftazidime-resistance was seen in 51.6% of all K. pneumoniae isolates, and all these isolates were inferred to be ESBL producers. All isolates were sensitive to imipenem. Susceptibility to gentamicin was 90.5%. The mean continuous hospital stay prior to the detection of bacteremia was 13.7 days overall, but significantly longer in the CRKP group (21.9 d) compared to the CSKP group (4.3 d) (P = 0.003). Children with CRKP were more likely to have received antibiotics in the 2 weeks prior to detection of bacteremia (87.5% of cases) than the CSKP group (20.0% of cases) (P = 0.0008). Sepsis-related mortality was higher in those with CRKP (50.0%) than in the CSKP group (13.3%) (P = 0.02). Patients who did not receive CRKP-directed antibiotics within 48 hours of admission were more likely to have a fatal outcome than those who did (P = 0.009). Logistic regression analysis identified use of third-generation cephalosporins 2 weeks prior to presentation and a hospital stay of 2 weeks or more as independent risk factors for development of CRKP.
CONCLUSIONS: More than half of total K. pneumoniae isolated from blood cultures in the unit were ceftazidime-resistant. Children with febrile neutropenia with prolonged hospital stay and recent prior antibiotic exposure are at high risk of developing CRKP bacteremia. Mortality was significantly higher in this group. Early commencement of appropriate antibiotics (e.g., imipenem with or without gentamicin), according to susceptibility study results, may be beneficial in such circumstances.
DESIGN: Prospective study.
PATIENTS AND METHODS: Patients were followed up endoscopically at 3, 6, 12 and 24 months after successful H. pylori eradication and duodenal ulcer healing. H. pylori status was determined by culture, rapid urease test, Gram's stain of a fresh tissue smear and histological examination of antral biopsies and rapid urease test and histological examination of corpus biopsies.
MAIN OUTCOME MEASURES: Duodenal ulcer healing, H. pylori reinfection.
RESULTS: Thirty-eight patients with duodenal ulcer disease (35 active, 3 healed) had successfully eradicated H. pylori following treatment with omeprazole/amoxycillin (n = 11), omeprazole/amoxycillin/metronidazole (n = 16) and colloidal bismuth subcitrate/ amoxycillin/metronidazole (n = 11). All patients with active duodenal ulcer had healed ulcers at the end of therapy. Thirty-five of 38 patients were seen according to schedule up to 2 years; two patients were seen up to 12 months and one up to 6 months only. Reinfection with H. pylori was not recorded in any of our patients. Shallow duodenal ulcers were noted in three patients at 1-year follow-up, two of whom admitted to taking non-steroidal anti-inflammatory drugs (NSAIDs); H. pylori status was negative in all three. Subsequent follow-up revealed spontaneous healing of the ulcers in all three patients. At 2 years, one patient whose H. pylori status was negative had recurrence of duodenal ulcer. All of the three patients who defaulted subsequent to follow-up were negative for H. pylori and had healed ulcers on follow-up endoscopy at 6 and 12 months.
CONCLUSION: Reinfection rate with H. pylori was zero in a group of South-East Asian patients who had successfully eradicated the infection. Duodenal ulcer relapse was also low (2.9%) in this group of patients at 2 years.