METHODS: Regulators were overproduced using a pBAD expression vector. Antibiotic susceptibility was measured using disc testing. Envelope permeability was estimated using a fluorescent dye accumulation assay. Porin and efflux pump production was quantified using proteomics and validated using real-time quantitative RT-PCR.
RESULTS: Envelope permeability and antibiotic disc inhibition zone diameters both reduced during overproduction of RamA and to a lesser extent RarA or SoxS, but did not change following overproduction of MarA. These effects were associated with overproduction of the efflux pumps AcrAB (for RamA and SoxS) and OqxAB (for RamA and RarA) and the outer membrane protein TolC (for all regulators). Effects on porin production were strain specific.
CONCLUSIONS: RamA is the most potent regulator of antibiotic permeability in K. pneumoniae, followed by RarA then SoxS, with MarA having very little effect. This observed relative potency correlates well with the frequency at which these regulators are reportedly overproduced in clinical isolates.
METHODS: Data from perinatally HIV-infected, antiretroviral-naïve patients initiated on NNRTI-based ART aged 10-19 years who had ≥6 months of follow-up were analyzed. Competing risk regression was used to assess predictors of NNRTI substitution and clinical failure (World Health Organization Stage 3/4 event or death). Viral suppression was defined as a viral load <400 copies/mL.
RESULTS: Data from 534 adolescents met our inclusion criteria (56.2% female; median age at treatment initiation 11.8 years). After 5 years of treatment, median height-for-age z score increased from -2.3 to -1.6, and median CD4+ cell count increased from 131 to 580 cells/mm(3). The proportion of patients with viral suppression after 6 months was 87.6% and remained >80% up to 5 years of follow-up. NNRTI substitution and clinical failure occurred at rates of 4.9 and 1.4 events per 100 patient-years, respectively. Not using cotrimoxazole prophylaxis at ART initiation was associated with NNRTI substitution (hazard ratio [HR], 1.5 vs. using; 95% confidence interval [CI] = 1.0-2.2; p = .05). Baseline CD4+ count ≤200 cells/mm(3) (HR, 3.3 vs. >200; 95% CI = 1.2-8.9; p = .02) and not using cotrimoxazole prophylaxis at ART initiation (HR, 2.1 vs. using; 95% CI = 1.0-4.6; p = .05) were both associated with clinical failure.
CONCLUSIONS: Despite late ART initiation, adolescents achieved good rates of catch-up growth, CD4+ count recovery, and virological suppression. Earlier ART initiation and routine cotrimoxazole prophylaxis in this population may help to reduce current rates of NNRTI substitution and clinical failure.
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.
METHODS: The patients selected had unequivocal evidence of H. pylori infection based on urease test, culture and histology on antral and corpus biopsies obtained at endoscopy. Patients received pantoprazole 40 mg twice a day, clarithromycin 500 mg twice a day and amoxycillin 1 g twice a day for 1 week and were assessed for successful eradication at least 4 weeks after completion of therapy by repeat gastroscopy and gastric biopsies. Eradication was defined as absence of bacteria in both antral and corpus biopsies tested by culture, histology and urease test.
RESULTS: One hundred and six patients were recruited for the study. The mean age was 48.0 years (range: 23-74 years). Four patients defaulted follow up and five patients were not compliant (taking less than 85%) with medications. Eradication rates on per-protocol analysis were: 88/97 (90.7%; 95% CI: 83.1-95.7); and on intention-to-treat analysis they were: 88/106 (83.0%; 95% CI: 75.9-90.2). Side-effects were in general mild and tolerable: 57 of 106 (53.7%) patients complained of a bitter taste; 15 (14.1%) complained of giddiness; 10 (9.4%) complained of increased abdominal pain; 11 (11.5%) complained of lethargy and 16 (15.1%) complained of loose motions. Pre-treatment metronidazole resistance was encountered in 57/74 strains (77.0%). Clarithromycin resistance was not encountered in any of the strains.
CONCLUSIONS: The pantoprazole 1-week triple therapy with amoxycillin and clarithromycin is effective in H. pylori eradication. The treatment was well tolerated by patients. Metronidazole resistance was reported in a high percentage of strains isolated from patients. Clarithromycin resistance was, however, not detected in any of the strains.
MATERIALS AND METHODS: A prospective epidemiologic and microbiologic study was conducted of MRKP isolated from the blood and wound of a boy with necrotizing fasciitis after a 7-day course of ceftazidime and amikacin. In the following 2 weeks, phenotypically similar MRKP were isolated from the blood cultures of four other patients and rectal swabs of another three patients and two liquid soap samples located in the same ward.
RESULTS: Antimicrobial profiles demonstrated that all the isolates were resistant to ceftazidime, sensitive to imipenem and ciprofloxacin, and confirmed to be extended-spectrum beta-lactamase producers. Plasmids of varying molecular weights were present in all isolates. In eight of these isolates, which included four from blood, there were common large molecular weight plasmids ranging from 80 kb to 100 kb. Pulsed-field gel electrophoresis analysis using XbaI demonstrated six different DNA profiles, A to F. Profile A was shared by two blood culture isolates and were related by 91%. Profile B was found in one rectal swab isolate and one isolate from liquid soap and were related by 94%. Profile C was shared by one blood isolate and one liquid soap isolate and showed 100% relatedness. Profiles D, E, and F each were demonstrated by one blood isolate and two rectal swab isolates, respectively. These showed only 65% relatedness.
CONCLUSIONS: The MRKP strains in this outbreak were not clonal in origin. The decline of the outbreak after 4 weeks was attributed to the reemphasis of standard infection control procedures and the implementation of a program that addressed sites of environmental contamination.
METHODS: One hundred isolates of S. typhi in humans (50 MDR and 50 antibiotic-sensitive isolates) from sporadic cases of typhoid fever were analyzed by Vi-phage typing, antibiograms and PFGE.
RESULTS: The MDR S. typhi strains were resistant to ampicillin, chloramphenicol, and trimethoprim-sulfamethoxazole. Analysis by PFGE showed that 50 MDR isolates of S. typhi had a single, homogenous PFGE profile, which was distinctly different from that of 50 antibiotic-sensitive isolates obtained in the same time frame from the same area. This latter group of isolates showed much greater diversity of PFGE profiles, as has been observed in other endemic regions.
CONCLUSIONS: Multidrug-resistant and antibiotic-susceptible strains of S. typhi can coexist in endemic areas as epidemiologically independent pathogens and are not in competition for continued persistence and transmission.