Resistance transfer in mixed cultures of Staphylococcus aureus

Transfer of resistance markers was regularly observed in mixed cultures of pairs of constructed strains of Staphylococcus aureus. This transfer was shown to be due to general transduction and required a lysogenic donor strain, carrying a transducing phage of serotype B and a transducible plasmid, and an acceptor strain without either strong restriction or an incompatible plasmid. Transfer was sometimes bidirectional when both strains carried a transducing phage. Unidirectional transfer occurred when the acceptor strain was immune. When the acceptor was sensitive to the donor phage, reversed transfer of a marker from the acceptor to the donor could take place. The kinetics of transfer are governed by the rate of phage production, the rate of phage adsorption and the frequency of transduction. A mathematical model has been developed to describe the interplay of these factors. The numbers of transductants observed in mixed cultures agreed with those expected from the model. Transfer was also observed in mixed cultures of constructed strains and wild-type strains. Transfer between wild-type strains is also possible, but was not observed in many combinations because of lack of transducing phage, strong restriction or other factors. Transfer was also observed in local lesions in mice infected with two strains and in mixtures inoculated on to human skin.     

Induction of chromosomal beta-lactamases by different concentrations of clavulanic acid in combination with ticarcillin

The effect of different concentrations of clavulanic acid (CA) in combination with ticarcillin on beta-lactamase production and ticarcillin MIC was studied in four clinical isolates of Pseudomonas aeruginosa, Enterobacter cloacae, Serratia marcescens, Citrobacter freundii and indole positive Proteus strains. Ticarcillin alone showed a low inducing effect for all species tested, Ser. marcescens excepted. The increase in beta-lactamase activity after addition of CA (2-10 mg/l) was strain and species dependent. No synergy or antagonism was observed on the ticarcillin MIC for the micro-organisms producing only a chromosomally mediated beta-lactamase, though the susceptibility to ticarcillin strongly increased if the strains also produced a plasmid-mediated beta-lactamase. Addition of 50 or 100 mg/l CA resulted in all strains. C. freundii excepted, in a strong increase in beta-lactamase activity and in a strong synergistic effect on the ticarcillin MIC. However, these concentrations are unlikely to be achieved at clinical doses. Thus, irrespective of the inducing effect of ticarcillin and CA (2-10 mg/l) combinations, induction of the chromosomal beta-lactamase did not result in a decrease in ticarcillin susceptibility.     

A study of non-antibiotic versus antibiotic prophylaxis for recurrent urinary-tract infections in women (the NAPRUTI study)

Patient enrolment in the 'Non-antibiotic versus antibiotic prophylaxis for recurrent urinary-tract infections' (NAPRUTI) study was started in September 2005. In this study of women with recurrent urinary-tract infections we aim to investigate the effect of 12 months of non-antibiotic prophylaxis in comparison with antibiotic prophylaxis on the rate of recurrence of urinary-tract infections and the development of antibiotic resistance. The study consists of two interlinked, randomised, clinical non-inferiority trials. In one trial, 280 premenopausal women will receive either cranberry capsules (twice daily 500 mg) or standardised antibiotic therapy (once daily 480 mg trimethoprim-sulfamethoxazole). In the other trial, 280 postmenopausal women will receive either oral lactobacilli (twice daily a capsule with > 10(9) colony-forming units of Lactobacillus rhamnosus GR-1 and Lactobacillus reuteri RC-14) or standardised antibiotic therapy. Non-inferiority of non-antibiotic prophylaxis would be attractive given its potential to reduce the prevalence of microbial resistance to antibiotics significantly.     

Intraoperative ultrasound examination of the brain

In a preliminary demonstration of cranial intraoperative real-time ultrasound, both supratentorial and posterior fossa scans displayed the pertinent anatomy. A grade III astrocytoma was visualized on the supratentorial scan as well. Ultrasound may be valuable for surgical planning and biopsy procedures because of its reliable depiction of intracranial anatomy and ease of use.     

Erythromycin resistance in the commensal throat flora of patients visiting the general practitioner: a reservoir for resistance genes for potential pathogenic bacteria

The prevalence and mechanism of erythromycin resistance in commensal throat streptococci was determined from October 2000 until December 2002 as part of an ongoing study of the NIVEL in general practice patients (N=678). Resistance prevalence for 1mg/L and 16 mg/L erythromycin was 57% and 20%, respectively. The percentage of total commensal flora resistant within each patient ranged from 1% to 100% (median, 1%). mefA was predominantly found among isolates on the 1mg/L plates, and ermB was found in 64% of the isolates on the 16 mg/L plates. Erythromycin resistance was transferred from a commensal isolate to Streptococcus pneumoniae with a frequency of 1 x 10(-9). Commensal streptococci of general practice patients in The Netherlands form a large reservoir of transferable erythromycin resistance (genes) for potential pathogenic microorganisms.     

Molecular characterization of Staphylococcus aureus bloodstream isolates collected in a Dutch University Hospital between 1999 and 2006

We observed that, between 1999 and 2006, up to 50% of the methicillin-susceptible Staphylococcus aureus (MSSA) bloodstream isolates in our hospital had a genetic background common to endemic methicillin-resistant S. aureus clones (clonal complex 5 [CC5], CC8, CC22, CC30, and CC45). Furthermore, several successful MSSA lineages, such as CC7 and CC15, were observed.     

Q-angle, Pelvic width, and Intercondylar notch width as predictors of knee injuries in women soccer players in South Africa

Objective

To investigate the association between the three anatomical factors of Q-angle (QA), pelvic width (PW) and Intercondylar notch width (INW) and knee injuries among the U-23 female soccer players of South Africa

Methods

The study is a case-control prospective study design. Twenty four U-23 women soccer players of the South African team were purposively chosen to participate in this study. Participants were divided into two groups: group1 (Case) was those with knee injuries, while those without injuries were in group-2 (Control). PW and INW were measured after X-rays of the hip were taken while the QA was measured manually with the goniomenter. Association between anatomical factors and knee injuries were tested with ANOVA.

Results

Q-angle ranged from 14° to 18° for both injured and non injured groups. PW was between 24 –29 cm for both injured and non injured groups. INW was between 1.3mm and 2.8mm for the right and between 1.4mm and 2.5mm for the left notch for the injured group, while INW for the right and left of the non injured group were between 1.7mm to 2.1mm and 1.8mm to 2.1mm, respectively No significant association between knee injuries and each of the anatomical factors was found QA (p= 0.74), PW (p=0.34), INW (right and left respectively) (p=0.142 & p=0.089).

Conclusion

The three anatomical factors of QA, PW and INW could not be used to predict knee injuries amongst the U-23 female players in South Africa.     

Prevalence of community-associated meticillin-resistant Staphylococcus aureus and Panton–Valentine leucocidin-positive S. aureus in general practice patients with skin and soft tissue infections in the northern and southern regions of The Netherlands

The purpose of this investigation was to determine the prevalence of community-associated meticillin-resistant Staphylococcus aureus (CA-MRSA) and Panton–Valentine leucocidin (PVL)-positive S. aureus in general practice (GP) patients with skin and soft tissue infections (SSTI) in the northern (Groningen and Drenthe) and southern (Limburg) regions of The Netherlands. Secondary objectives were to assess the possible risk factors for patients with SSTI caused by S. aureus and PVL-positive S. aureus using a questionnaire-based survey. From 2007 to 2008, wound and nose cultures were obtained from patients with SSTI in general practice. These swabs were analysed for the presence of S. aureus and the antibiotic susceptibility was determined. The presence of the PVL toxin gene was determined by polymerase chain reaction (PCR) and the genetic background with the use of spa typing. A survey was performed to detect risk factors for S. aureus infection and for the presence of PVL toxin.S. aureus was isolated from 219 out of 314 (70%) patients with SSTI, of which two (0.9%) patients were MRSA-positive. In 25 (11%) patients, the PVL toxin gene was found. A higher prevalence of PVL-positive S. aureus of patients with SSTI was found in the northern region compared to the south (p < 0.05). Regional differences were found in the spa types of PVL-positive S. aureus isolates, and for PVL-negative S. aureus isolates, the genetic background was similar in both regions. The prevalence of CA-MRSA in GP patients with SSTI in The Netherlands is low. Regional differences were found in the prevalence of PVL-positive S. aureus isolates from GP patients with SSTI. Household contacts having similar symptoms were found to be a risk factor for SSTI with S. aureus.