Background Stenotrophomonas maltophilia is associated with respiratory tract infections in immunocompromised patients, and it has emerged as an important nosocomial pathogen, with admission to intensive care units (ICUs) and ventilators as recognized risk factors. Aim To describe the investigation of a sudden increase in patients with pneumonia caused by S. maltophilia at a Swedish ICU and the control measures taken. Methods Lower respiratory tract cultures from patients admitted to the ICU were obtained, and environmental cultures were collected from sink drains and medical equipment. Isolates identified as S. maltophilia were subjected to antibiotic susceptibility testing and whole genome sequencing (WGS). Findings A total of 17 S. maltophilia isolates were found (four from patients and 13 from the environment). The WGS identified two outbreak clones, sequence type (ST) 361 and ST138, and seven unique ones. Most likely, the outbreak clones originated from two sinks, and transmission was enhanced by a calorimeter. After changing the sink and calorimeter routines, no more cases were registered. Conclusion Acquisition of S. maltophilia from the hospital environment appears to be easy, especially if water is involved. To control this bacterium, better knowledge of its transmission routes in hospital environments is required.

Several retrospective studies have identified hospital sinks as reservoirs of Gram-negative bacteria. The aim of this study was to prospectively investigate the bacterial transmission from sinks to patients and if self-disinfecting sinks could reduce this risk. Samples were collected weekly from sinks (self-disinfecting, treated with boiling water, not treated) and patients in the Burn Centre at Linköping University Hospital, Sweden. The antibiotic susceptibility of Gram-negative isolates was tested, and eight randomly chosen patient isolates and their connected sink isolates were subjected to whole genome sequencing (WGS). Of 489 sink samples, 232 (47%) showed growth. The most frequent findings were Stenotrophomonas maltophilia (n = 130), Pseudomonas aeruginosa (n = 128), and Acinetobacter spp. (n = 55). Bacterial growth was observed in 20% of the samplings from the self-disinfecting sinks and in 57% from the sinks treated with boiling water (p = 0.0029). WGS recognized one transmission of Escherichia coli sampled from an untreated sink to a patient admitted to the same room. In conclusion, the results showed that sinks can serve as reservoirs of Gram-negative bacteria and that self-disinfecting sinks can reduce the transmission risk. Installing self-disinfecting sinks in intensive care units is an important measure in preventing nosocomial infection among critically ill patients.

The objective of this study was to investigate a sudden increase in methicillin-resistant Staphylococcus aureus (MRSA) cases primarily in one maternity ward at the Center for Children's and Women's Health at Link€ oping University Hospital, Sweden. Approximately 300 individuals including patients, their family members, and healthcare workers were screened for MRSA. The antibiotic susceptibility was tested and isolates polymerase chain reaction (PCR)-positive for the mecA gene were spa typed. Isolates with the same antibiogram and spa type were further whole genome sequenced. Compliance to current cleaning and hygiene routines was also controlled, and environmental samples collected. The results showed that a total of 13 individuals were involved in the outbreak. It was caused by a t386 MRSA strain (ST-1, NCBI-accession AB505628) with additional resistance to erythromycin and clindamycin. All cases were epidemiologically connected to the index patient, who had recently emigrated from a high-endemic area for MRSA. With improved cleaning and better compliance to basic hygiene routines, no further cases were reported. This study demonstrates how rapid an MRSA strain can disseminate in a ward with susceptible patients and insufficient cleaning and hygiene. For a better control of MRSA, clinical cultures and screening samples need to be obtained early and more extensively than according to the current recommendations.

Background Vancomycin-resistant Enterococcus faecium (VRE) is a nosocomial pathogen that causes infection mainly in patients with critical illnesses in intensive care units, severe underlying diseases or weakened immune systems. Intensive pretreatment with antibiotics and the use of urinary catheters also constitute a risk. Due to its hardy nature, the bacterium can survive for long periods in a hospital environment. The aim of this study was to describe the investigation of a sudden increase in VRE cases admitted to the surgical unit at Vrinnevi Hospital in Norrköping, Sweden, and the control measures taken. Methods Faecal cultures from patients admitted to the surgical unit were obtained, and environmental cultures were collected from different locations in patient rooms and medical devices. In addition, screening samples were obtained from units with high-risk patients in Östergötland County. Isolates identified as E. faecium were subjected to antibiotic susceptibility testing. Vancomycin-resistant isolates PCR-positive for the vanA/vanB gene were further analysed with whole-genome sequencing (WGS). Results A total of 35 VRE isolates were found (22 from patients and 13 from the environment). The WGS identified three outbreak clusters, sequence type (ST) 203, ST 1839 and ST 80, and one unique clone (ST 612). The ST 203 clone predominated among VRE cases admitted to the surgical unit. Conclusions With prompt infection control measures, the VRE outbreak was over after approximately four months. To prevent further outbreaks of VRE, active screening, antibiotic stewardship, improved cleaning and hand hygiene, and restriction of multiple-bed rooms is essential.