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- Lindqvist, Maria, 1983-
(author)
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Epidemiological and molecular biological studies of multi-resistant methicillin-susceptible Staphylococcus aureus
- 2014
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Doctoral thesis (other academic/artistic)abstract
- Antibiotic resistance is increasingly recognised as a major problem and threat. During the last decades Gram-positive bacteria in general, and methicillin-resistant Staphylococcus aureus (MRSA) in particular, have been in focus both concerning matters of antibiotic resistance and as pathogens causing health care-associated (nosocomial) infections. In contrast to MRSA, studies on clonal distribution of methicillin-susceptible S. aureus (MSSA) are scarce. However, interest in MSSA has increased since it was shown that MRSA emerges from susceptible backgrounds by acquisition of a staphylococcal cassette chromosome element, carrying the mecA gene encoding methicillin-resistance (SCCmec).In an outbreak investigation of MRSA in Östergötland County, Sweden, in 2005, a high incidence of MSSA isolates with concomitant resistance to erythromycin, clindamycin and tobramycin (ECT-R) was detected. Analysis showed that 91 % of the investigated isolates were genetically related (clonal). The ECT-R clone was divided into four different but closely related patterns with pulsed-field gel electrophoresis (PFGE), and was designated spa type t002. Whole genome sequencing revealed that the ECT-R clone carried a pseudo-SCC element estimated to be 12 kb in size, showing a resemblance of more than 99 % with the SCCmec type II element of MRSA strain N315 (New York/Japan clone). This suggested a probable derivation from a highly successful MRSA strain, which had partially excised its SCCmec. The clonal outbreak was concentrated in eight hospital departments and two primary care centres, all located in the city of Linköping. Despite a high exchange of patients with the hospitals in the neighbouring counties in southeast Sweden (Jönköping- and Kalmar County), the ECT-R clone seemed to be limited to Östergötland County. However, a tobramycin-resistant clone predominated by isolates of spa type t084 was found in all three counties in southeast Sweden, and in particular among newborns, suggesting inter-hospital transmission.The ECT-R clone has survived as an abundant MSSA clone for a decade in Östergötland County, which indicates an insufficiency in the maintenance of basic hygiene guidelines, and that the clone probably possesses mechanisms of virulence and transmission that are yet to be discovered.
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| 2. |
- Lindqvist, Maria, et al.
(author)
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Genetic relatedness of multi-resistant methicillin-susceptible Staphylococcus aureus in southeast Sweden
- 2014
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Other publication (other academic/artistic)abstract
- Background: A high exchange of patients occurs between the hospitals in southeast Sweden, resulting in a possible transmission of nosocomial pathogens. The objective of this study was to investigate the incidence and possible genetic relatedness of multi-resistant methicillinsusceptible Staphylococcus aureus (MSSA) in the region in general, and in particular the possible persistence and transmission of the ECT-R clone (t002) showing resistance to erythromycin, clindamycin and tobramycin previously found in Östergötland County.Methods: Three groups of S. aureus isolates with different antibiotic resistance profiles, including the ECT-R profile, were collected from the three County Councils in southeast Sweden and investigated with spa typing, real-time PCR targeting the staphylococcal cassette chromosome (SCC) mec right extremity junction (MREJ), and microarray.Results: All isolates with the ECT-R resistance profile (n = 12) from Östergötland County and two additional isolates with another antibiotic resistance profile were designated spa type t002, MREJ type ii, and were clustered in the same clonal cluster (CC) (i.e. CC5) by the microarray result, indicating the persistence of the ECT-R clone. In addition, 60 % of the isolates belonged to CC15 from newborns, with 94 % sharing spa type t084, indicating interhospital transmission.Conclusions: The persistence of the ECT-R clone and the possible transmission of the t084 strain indicate that there is still an insufficiency in the maintenance of basic hygiene guidelines. The ECT-R clone probably possesses mechanisms of virulence and transmission that make it so successful.
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| 3. |
- Samuelsson, Annika, 1964-, et al.
(author)
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Late onset neonatal sepsis, risk factors and interventions: an analysis of recurrent outbreaks of Serratia marcescens 2006-2011
- 2014
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In: Journal of Hospital Infection. - : Elsevier. - 0195-6701 .- 1532-2939. ; 86:1, s. 57-63
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Journal article (peer-reviewed)abstract
- Background: during the period 2006 to 2011 we observed 11 patients with Serratia marcescens sepsis, a total of 47 patients were colonised due to spread of different clones. These recurrent clusters brought about interventions to reduce spread between patients.Aim: to evaluate the effect of stepwise introduced interventions to prevent S marcescens colonisation/sepsis and to analyse risk factors for late onset sepsis (LOS).Methods: to evaluate the interventions an open retrospective observational study was performed. A retrospective case-control study was performed to analyse risk factors for LOS.Findings: main findings of this study were the decrease in S marcescens sepsis and colonisation after the stepwise adoption of hygiene interventions, as well as identifying low gestational age, low birth weight, indwelling central venous or umbilical catheter and ventilator treatment as risk factors for LOS. Compliance to basic hygiene guidelines was the only intervention continuously monitored from late 2007. Compliance increased gradually to a steady high level early 2009. There was a decrease in LOS with S marcescens (LOS-Ser) clustering after the second quarter of 2008. After the first quarter of 2009 we saw a decrease in S marcescens colonisation.Conclusion: We were not able to isolate specific effects of each intervention, but an update of our antibiotic policy probably had effect on the occurrence of LOS-ser. The delayed effect of interventions on S marcescens colonisation was probably due to the time it takes for new routines to have impact, illustrated by the gradual increase in compliance to basic hygiene guidelines.
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