Sulphonamide resistant commensal Neisseria with alterations in the dihydropteroate synthase can be isolated from carriers not exposed to sulphonamides

BACKGROUND: Development of sulphonamide resistance in Neisseria meningitidis has been suggested to involve horizontal DNA-transfer from a commensal Neisseria species. In this study, we isolated commensal Neisseria from throat specimens and examined the isolates with respect to sulphonamide resistance. RESULTS: Three resistant clones were identified and the resistance phenotype could be explained by amino acid variations in their dihydropteroate synthase, the target molecule for sulphonamides. Some of these variations occurred in positions corresponding to previously detected variations in resistant N. meningitidis. CONCLUSIONS: Sulphonamide resistant commensal Neisseria were isolated from an environment not exposed to sulphonamides, suggesting that resistant Neisseria has become a natural part of the commensal throat flora

Cotrimoxazole Prophylaxis Specifically Selects for Cotrimoxazole Resistance in Streptococcus mutans and Streptococcus sobrinus with Varied Polymorphisms in the Target Genes folA and folP

The selection of antibiotic resistance by cotrimoxazole prophylaxis was evaluated, and we characterized the mechanism of cotrimoxazole resistance in Streptococcus mutans and Streptococcus sobrinus. In vitro susceptibility to six antibiotics was evaluated on 64 mutans streptococci group (MSG) isolates from a cotrimoxazole prophylaxis group and compared to 84 MSG isolates from a nonprophylaxis group. The folA and folP genes were sequenced and compared with reference sequences at NCBI. Only resistance to cotrimoxazole was significantly higher in the prophylaxis group (54.7% versus 15.5%, OR = 6.59, 95% CI: 2.89–15.3, P < 0.05). Resistance to amoxicillin, ceftriaxone, chloramphenicol, erythromycin, and tetracycline was 1.4%, 25.5%, 6.2%, 6.5%, and 29.6% of the isolates, respectively. Considerable polymorphisms were found in the folP gene in S. mutans, but this could not be linked to sulfonamide drug resistance. No variation was seen in folP or folA genes of S. sobrinus. Genetic transfer of folate pathway genes seems unlikely in these isolates

Molecular and genetic characterization of emerging carbapenemase-producing Acinetobacter baumannii strains from patients and hospital environments in Bangladesh

Background Carbapenemase-producing multidrug-resistant (MDR) Acinetobacter baumannii is a global health care problem. MDR A. baumannii has emerged as an important nosocomial pathogen, costing many lives worldwide including Bangladesh. Aim To investigate the detailed molecular epidemiology of carbapenem-resistant A. baumannii (CRAB) both from patients and the hospital environment, to shed light on genetic characteristics and transmission dynamics. Methods A set of 49 clinical A. baumannii strains collected during early 2015 was received from the clinical microbiology laboratory of Dhaka Medical College Hospital (DMCH) in Bangladesh. Additionaly, 100 environmental samples were also collected from the hospital surfaces of Dhaka Medical College Hospital and analyzed for carbapenamase-producing A. baumannii. CRAB were identified by culture on selective plates, biochemical testing and MALDI-TOF. All isolates were characterized by susceptibility testing, realtime-PCRs, conventional PCR, MLST and sequencing. Findings Clinical A. baumannii were resistant to ciprofloxacin (100%), imipenem (91.8%), meropenem (91.8%), gentamicin (91.8%), amikacin (87.7%), and trimethoprim-sulfamethoxazole (61.2%). The majority (59%) of the isolates were MDR. All environmental A. baumannii (n=10) were resistant to imipenem, meropenem, gentamicin, amikacin, and ciprofloxacin. Strains carried the following antibiotic resistant genes; blaOXA-23, blaOXA-58, blaPER-7, qnrB1, qnrC1, aac(6′)1b-cr and armA. A total of 36 different clones were identified by rep-PCR and common clonal clusters were found both in patients and hospital environments. MLST analysis revealed different sequence types (ST2, ST10, ST149, ST575, ST1063 and ST1065). In clinical and environmental settings. A. baumannii ST2 dominated in both clinical and environmental settings. Both clinical and environmental A. baumannii strains with known STs carried several biofilm-related genes; bap, csuE, and pgaB. Conclusion Widespread dissemination of MDR A. baumannii in the DMC hospital of Bangladesh is a serious problem

Efficacy of artemether-lumefantrine in treatment of malaria among under-fives and prevalence of drug resistance markers in Igombe-Mwanza, north-western Tanzania

\ud \ud Drug resistance to anti-malarials is a major public health problem worldwide. This study aimed at establishing the efficacy of artemether-lumefantrine (ACT) in Igombe-Mwanza, north-western Tanzania after a few years of ACT use, and establish the prevalence of mutations in key targets for artemisinin, chloroquine and sulphadoxine/pyrimetamine (SP) drugs. A prospective single cohort study was conducted at Igombe health centre using artemether-lumefantrine combination therapy between February 2010 and March 2011. The follow-up period was 28 days and outcome measures were according to WHO guidelines. Blood was collected on Whatman filter paper for DNA analysis. DNA extraction was done using TRIS-EDTA method, and mutations in Pfcrt, Pfmdr1, Pfdhfr, Pfdhps and Pfatp6 were detected using PCR-RFLP methods established previously. A total of 103 patients completed the 28 days follow-up. The mean haemoglobin was 8.9 g/dl (range 5.0 to 14.5 g/dl) and mean parasite density was 5,608 parasites/μl. Average parasite clearance time was 34.7 hours and all patients cleared the parasites by day 3. There was no early treatment failure in this study. Late clinical failure was seen in three (2.9%) patients and late parasitological failure (LPF) was seen in two (1.9%). PCR-corrected LPF was 1% and adequate clinical and parasitological response was 96%. The majority of parasites have wild type alleles on pfcrt 76 and pfmdr1 86 positions being 87.8% and 93.7% respectively. Mutant parasites predominated at pfdhfr gene at the main three positions 108, 51 and 59 with prevalence of 94.8%, 75.3% and 82.5% respectively. Post-treatment parasites had more wild types of pfdhps at position 437 and 540 than pre-treatment parasites. No mutation was seen in pfatp6 769 in re-infecting or recrudescing parasites. The efficacy of artemether-lumefantrine for treatment of uncomplicated malaria is still high in the study area although the rate of re-infection is higher than previously reported. Parasite clearance after 48 hours was lower compared to previous studies. The prevalence of wild type allele pfcrt 76 K and pfmdr1 86 N was high in the study area while markers for SP resistance is still high. Artemether-lumefantrine may be selecting for wild type alleles on both positions (437 and 540) of pfdhps

Haptoglobin gene diversity and incidence of uncomplicated malaria among children in Iganga, Uganda

Background Haptoglobin (Hp) is an acute phase protein that takes part in systemic regulation of haem during Plasmodium falciparum infections. Numerous genotypes of haptoglobin have been reported in malaria endemic populations. In this study, the relationship between haptoglobin genotypes and incidence of uncomplicated malaria in a cohort of children living in a malaria-endemic area of Uganda was determined. Methods This is an extension of a longitudinal study comprising of 423 children aged between six months and nine years, who were actively followed up for one year. Malaria episodes occurring in the cohort children were detected and the affected children treated with national policy drug regimen. Haptoglobin genotypes were determined by an allele-specific PCR method and their frequencies were calculated. A multivariate negative binomial regression model was used to estimate the impact of haptoglobin genotypes on incidence of uncomplicated malaria in the children’s cohort. In all statistical tests, a P–value of &lt; 0.05 was considered as significant. Results The prevalence of the Hp 1–1, Hp 2–1 and Hp 2–2 genotypes in the children’s cohort was 41%, 36.2% and 22.9%, respectively. The overall frequency for the Hp 1 allele was 59%, while Hp 2 allele occurred at a frequency of 41%. After adjustment of incidence rates for age, insecticide treated bed net (ITN) use and malaria history, the incidence of uncomplicated malaria for children carrying the Hp 2–2 genotype and those with the Hp 2–1 genotype was statistically similar (P = 0.41). Also, no difference in the incidence of uncomplicated malaria was observed between children carrying the Hp 1–1 genotype and those having the Hp 2–1 genotype (P = 0.84) or between Hp 2–2 Vs Hp 1–1 genotypes (P = 0.50). Conclusions This study showed that the Hp 1–1 and Hp 2–1 genotypes each occur in nearly 4 in 10 children and the Hp 2–2 genotype occurs in 2 of every 10 children. No association with incidence of uncomplicated malaria was found. Additional studies of influence of haptoglobin genotypes on P. falciparum malaria severity are needed to understand the role of these genotypes in malarial protection.De två sista författarna delar sistaförfattarskapet</p

Prevalence of polymorphisms in glucose-6-phosphate dehydrogenase, sickle haemoglobin and nitric oxide synthase genes and their relationship with incidence of uncomplicated malaria in Iganga, Uganda

Background: Host genetics play an important role in Plasmodium falciparum malaria susceptibility. However, information on host genetic factors and their relationships with malaria in the vaccine trial site of Iganga, Uganda is limited. The main objective of this study was to determine the prevalence of selected host genetic markers and their relationship to malaria incidence in the vaccine trial site of Iganga, Uganda. In a 1-year longitudinal cohort study, 423 children aged below 9 years were recruited and their malaria episodes were investigated. Host genetic polymorphisms were assessed by PCR-RFLP, haemoglobin electrophoresis and DNA sequencing. Using a multivariate negative binomial regression model, estimates of the impact of human genetic polymorphisms on malaria incidence were performed. In all statistical tests, a P value of &lt; 0.05 was considered as significant. Results: The prevalences of sickle cell haemoglobin trait, G6PD c. 202 G &gt; A (rs 1050828) and NOS2 -954 G &gt; C (rs 1800482) variants were 26.6, 22.7 and 17.3%, respectively. Inducible nitric oxide synthase 2 (NOS2 -954 G&gt;C; rs 1800482) heterozygosity was associated with lower incidence of malaria in all age groups {Adjusted incident rates ratio (aIRR) 0.59; 95% CI [0.386-0.887]; P = 0.012)}. About 4% of study subjects had co-existence of sickle cell Hb trait and G6PD deficiency. Sickle cell Hb heterozygotes (Hb AS) aged less than 1 year experienced significantly more malaria episodes annually than children with normal haemoglobin (Hb AA) {aIRR = 1.98; 95% CI [1.240-3.175]; P = 0.004}. There was no significant influence of the sickle cell trait on malaria incidence among older children of 1-9 years. Conclusions: Mutation (NOS2 -954 G &gt; C; rs 1800482) of nitric oxide synthase 2 gene promoter was associated with a lower incidence of acute malaria. The normal haemoglobin (wild genotype; HbAA) was associated with reduced malaria incidence rates during the first year of life. More understanding of the interplay between host genetics and malaria susceptibility is required