Low risk of transmission of pathogenic bacteria between children and the assistance dog during animal-assisted therapy if strict rules are followed.

This study explored the bacterial transmission between patients and dogs during dog-assisted therapy (DAT). Twenty children (55% girls) with a median age of 7 years (range 3-17 years) were included. Two dogs assisted and the conditions were more restricted hygienically with dog 2. Samples from child and dog were collected and cultured before and after each DAT visit. The results showed that dog 1 transmitted bacteria repeatedly to the children. No bacteria were transmitted with dog 2. In conclusion, exchange of bacteria can occur between dog and child during DAT, but it can be reduced by simple infection control measures.

Prevalence of ß-lactamase genes in domestic washing machines and dishwashers and the impact of laundering processes on antibiotic-resistant bacteria.

AIMS: To investigate the prevalence of ß-lactamase genes in domestic washing machines and dishwashers, and the decontamination efficacy of laundering. METHODS AND RESULTS: For the first investigation, swab samples from washing machines (n = 29) and dishwashers (n = 24) were analysed by real-time quantitative PCR to detect genes encoding ß-lactamases. To test the impact of laundering on resistant bacteria, cotton test swatches were artificially contaminated with susceptible and resistant strains of Pseudomonas aeruginosa, Klebsiella pneumoniae and Staphylococcus aureus within a second investigation. They were washed in a domestic washing machine with or without activated oxygen bleach (AOB)-containing detergent at 20-50°C. ß-Lactamase genes (most commonly of the AmpC- and OXA-type) were detected in 79% of the washing machines and in 96% of the dishwashers and Pseudomonadaceae dominated the microbiota. The level of bacterial reduction after laundering was ≥80% for all Ps. aeruginosa and Kl. pneumoniae strains, while it was only 37-61% for the methicillin-resistant Staph. aureus outbreak strain. In general, the reduction was tendentially higher for susceptible bacteria than for the resistant outbreak strains, especially for Staph. aureus. CONCLUSIONS: ß-Lactamase genes seem to be frequently present in domestic appliances and may pose a potential risk for cross-contamination and horizontal transfer of genes encoding resistance against clinically important ß-lactams. In general, higher temperatures and the use of AOB can improve the reduction of antibiotic-resistant bacteria, including Staph. aureus which appears to be less susceptible to the decontamination effect of laundering. SIGNIFICANCE AND IMPACT OF THIS STUDY: Data on the presence of antibiotic-resistant bacteria in the domestic environment are limited. This study suggests that ß-lactamase genes in washing machines and dishwashers are frequent, and that antibiotic-resistant strains are generally more resistant to the used washing conditions.

High frequency of silver resistance genes in invasive isolates of Enterobacter and Klebsiella species.

BACKGROUND: Silver-based products have been marketed as an alternative to antibiotics, and their consumption has increased. Bacteria may, however, develop resistance to silver. AIM: To study the presence of genes encoding silver resistance (silE, silP, silS) over time in three clinically important Enterobacteriaceae genera. METHODS: Using polymerase chain reaction (PCR), 752 bloodstream isolates from the years 1990-2010 were investigated. Age, gender, and ward of patients were registered, and the susceptibility to antibiotics and silver nitrate was tested. Clonality and single nucleotide polymorphism were assessed with repetitive element sequence-based PCR, multi-locus sequence typing, and whole-genome sequencing. FINDINGS: Genes encoding silver resistance were detected most frequently in Enterobacter spp. (48%), followed by Klebsiella spp. (41%) and Escherichia coli 4%. Phenotypical resistance to silver nitrate was found in Enterobacter (13%) and Klebsiella (3%) isolates. The lowest carriage rate of sil genes was observed in blood isolates from the neonatology ward (24%), and the highest in blood isolates from the oncology/haematology wards (66%). Presence of sil genes was observed in international high-risk clones. Sequences of the sil and pco clusters indicated that a single mutational event in the silS gene could have caused the phenotypic resistance. CONCLUSION: Despite a restricted consumption of silver-based products in Swedish health care, silver resistance genes are widely represented in clinical isolates of Enterobacter and Klebsiella species. To avoid further selection and spread of silver-resistant bacteria with a high potential for healthcare-associated infections, the use of silver-based products needs to be controlled and the silver resistance monitored.

Dissemination of the multidrug-resistant extended-spectrum ß-lactamase-producing Escherichia coli O25b-ST131 clone and the role of house crow (Corvus splendens) foraging on hospital waste in Bangladesh.

Two hundred and thirty-eight faecal samples from crows foraging on hospital wastes were analysed for extended-spectrum ß-lactamase (ESBL)-producing Enterobacteriaceae. ESBL-producing crow isolates were characterized and compared with 31 patient isolates. Among the crows, 59% carried ESBL producers. These included Escherichia coli, Klebsiella pneumoniae, Raoultella terrigena and Enterobacter cloacae harbouring the genes for CTX-M-1, CTX-M-15, CTX-M-55, CTX-M-79, and CTX-M-14. Human isolates carried only the CTX-M-15 gene. Two-thirds of crow E. coli isolates and all human E. coli isolates were multidrug resistant. Crows and patients shared E. coli sequence types, including the epidemic E. coli O25b-ST131 clone. The scavenging behaviour of crows at poorly managed hospital waste dumps made them potential reservoirs of antibiotic resistance, including ESBLs.

Minor outbreak of extended-spectrum ß-lactamase-producing Klebsiella pneumoniae in an intensive care unit due to a contaminated sink.

During a period of seven months four patients on the neurosurgical intensive care unit at a tertiary care hospital in Sweden became infected or colonized by an extended-spectrum ß-lactamase-producing Klebsiella pneumoniae strain. The investigation revealed that the source of the outbreak was a contaminated sink. By replacing the sink and its plumbing and improving routines regarding sink practices, the outbreak was successfully controlled.

Alarming spread of vancomycin resistant enterococci in Sweden since 2007.

The total number of persons infected or colonised with vancomycin-resistant enterococci mandatorily reported to the Swedish Institute for Infectious Disease Control increased dramatically during 2007 and 2008. During a period of twenty months from 1 July 2007 to 28 February 2009, a total of 760 cases were reported compared with 194 cases reported during the entire period from 2000 to 2006. This rise was mainly attributed to a wide dissemination of vancomycin resistant enterococci which started in a number of hospitals in Stockholm in the autumn of 2007 and was followed by dissemination in various healthcare facilities (hospitals and homes for the elderly) in a further two Swedish counties in 2008. The majority of the cases (97%) were acquired in Sweden and among these, healthcare-acquired E. faecium vanB dominated (n=634). The majority of these isolates had identical or closely related pulsed-field gel electrophoresis patterns indicating clonal dissemination in the affected counties. The median minimum inhibitory concentration of vancomycin was 32 mg/L (ranging from 4 to >128 mg/L) and of teichoplanin 0.12 mg/L (ranging from 0.06 to 0.25 mg/L). Particular emphasis was placed on countermeasures such as screening, contact tracing, cleaning procedures, education in accurate use of infection control practices as well as increasing awareness of hygiene among patients and visitors. With these measures the dissemination rate decreased substantially, but new infections with the E. faecium vanB strain were still detected.

Characterization, and comparison, of human clinical and black-headed gull (Larus ridibundus) extended-spectrum beta-lactamase-producing bacterial isolates from Kalmar, on the southeast coast of Sweden.

BACKGROUND: Antibiotic resistance is one of the great challenges for modern healthcare. In Gram-negative bacteria, CTX-M-type extended-spectrum beta-lactamases (ESBLs) have been rapidly spreading through Europe since the early 2000s. In Sweden, ESBL-producing Escherichia coli are still rare, but a 3-fold increase has been seen from 2004 to 2007. Enterobacteria and normal flora of wild animals, with or without antibiotic resistance traits, constitute a potential source of human infection and colonization. We studied wild birds with the aim to understand the environmental dissemination of antibiotic resistance and, focusing on clinically relevant resistance types, we made comparisons with human clinical samples. METHODS: In this study, ESBL-producing human clinical isolates and isolates from juvenile black-headed gulls from Kalmar County hospital and the city of Kalmar, respectively, on the southeast coast of Sweden, were characterized and compared. RESULTS: Despite a low frequency of antibiotic resistance among the isolates from gulls, ESBL-producing E. coli isolates were found, two with bla(CTX-M-14) and one with bla(CTX-M-15). The same CTX-M types were dominant among human ESBL isolates. In addition, gull isolates were dispersed among the human samples in the PhenePlate clustering system, indicating that they neither differ from the human isolates nor form any separate clonal clustering. CONCLUSIONS: The finding of CTX-M-type ESBLs in E. coli isolated from black-headed gulls in Sweden, where 'background resistance' is low, is consistent with an ongoing environmental spread of these plasmid-borne resistance genes. The results indicate that a potential for transfer between the human population and environment exists even in countries with a low level of antibiotic resistance.

Hospital outbreak control requires joint efforts from hospital management, microbiology and infection control.

An outbreak of multidrug-resistant Klebsiella pneumoniae producing the extended-spectrum beta-lactamase CTX-M15 affected 247 mainly elderly patients in more than 30 wards in a 1000-bedded swedish teaching hospital between May 2005 and August 2007. A manual search of the hospital administrative records for possible contacts between cases in wards and outpatient settings revealed a complex chain of transmission. Faecal screening identified twice as many cases as cultures from clinical samples. Transmission occurred by direct and indirect patient-to-patient contact, facilitated by patient overcrowding. Interventions included formation of a steering group with economic power, increased bed numbers, better compliance with alcohol hand disinfection and hospital dress code, better hand hygiene for patients and improved cleaning. The cost of the interventions was estimated to be euro3 million. Special infection control policies were not necessary, but resources were needed to make existing policies possible to follow, and for educational efforts to improve compliance.

Effects of amoxicillin on the expression of cytokines during experimental acute otitis media caused by non-typeable Haemophilus influenzae.

Antibiotics are frequently prescribed when a diagnosis of acute otitis media (AOM) is made in childhood, but the effects of antibiotics on host-parasite interactions in the middle ear are not well defined. A rat model and PCR techniques were used to explore host responses during amoxicillin treatment of AOM caused by non-typeable Haemophilus influenzae (NTHi). The 5 day course of amoxicillin initiated at the otomicroscopic peak of the infection eradicated the bacteria and induced significant changes in the expression of cytokines. Interleukin (IL)-6, tumour necrosis factor-alpha and IL-10 were upregulated by the treatment, and the downregulation was slower than during the natural course. Amoxicillin inhibited the upregulation of transforming growth factor-beta, whereas IL-1alpha expression remained unaffected by the treatment. By comparing inflammatory host responses during treated and untreated NTHi AOM, new targets for modification of the course, or more specified and individualized treatments, may evolve.

[Vibrio vulnificus. A marine bacterium with lethal potential]. / Vibrio vulnificus. Havsbakterie med dödlig potential.

Vibrio vulnificus is a halophilic gram-negative rod widespread in the aquatic environment and associated with primary septicemia and severe wound infections. The first Swedish case was reported in 1994. Ever since, sporadic cases have occurred in the south of Sweden whenever the coastal water temperature has exceeded 20 degrees C. Critical for a successful outcome in these infections has been early diagnosis with appropriate antibiotic and surgical treatment. A review of this subject was prompted by two cases of fulminant septicemia, which both presented themselves as atypical erysipelas.

Penicillin treatment failure in group A streptococcal tonsillopharyngitis: no genetic difference found between strains isolated from failures and nonfailures.

Despite penicillin (pcV) treatment, tonsillopharyngitis caused by group A streptococci (GAS) is associated with bacterial failure rates as high as 25%. The reason for this rate of failure is not fully understood. One explanation might be that certain DNA profiles of GAS strains are responsible for treatment failures. Using arbitrarily primed polymerase chain reaction (AP-PCR), we compared the DNA profiles of GAS strains from 4 patients with several treatment failures following pcV treatment of tonsillopharyngitis with the profiles of strains of the same T type from patients who were clinically and bacteriologically cured after a single course of pcV. The isolates were obtained during the same time period and from the same geographic area. Thirty-seven strains of T types 4, 12, and R28 were investigated. Eleven different DNA profiles could be detected with the AP-PCR technique. Five DNA profiles were identified as T type 12, 3 as T type 4, and 3 as T type R28. The DNA profiles of the strains from the 4 patients with several treatment failures differed, but all isolates from each one of these patients exhibited the same or a very similar profile. The DNA profiles of the failure strains were also represented in nonfailure strains. Treatment failure in these 4 patients therefore seems to be due to insufficient eradication of GAS, rather than to reinfection with a new strain. The finding that the same DNA profile can be present in both failure and nonfailure strains suggests that the treatment failure may be to some extent host-related and not only due to bacterial factors.

Detection and localization of interleukin-6 in the rat middle ear during experimental acute otitis media, using mRNA in situ hybridization and immunohistochemistry.

OBJECTIVE: Otitis media is one of the most common diseases among children. A well-known sequela of acute, chronic, and secretory otitis media is tympanosclerosis. With the exception of surgery, there is no causal treatment available for this condition, which may cause hearing disabilities. This study aimed to describe the localization of interleukin (IL)-6 mRNA and its gene product in the rat middle ear during pneumococcal otitis media. IL-6 is known to be involved in inflammatory and bone remodeling processes. METHODS: Using an experimental model of pneumococcal acute otitis media, the expression of interleukin IL-6, was analyzed. Sprague-Dawley rats were sacrificed at different time points varying from 1 h to 6 days intervals after inoculation. The middle ears were analyzed by messenger RNA in situ hybridization, and by immunohistochemistry with cell-type specific antibodies directed against IL-6. RESULTS: Transcripts of IL-6 were observed only on day 1 post-inoculation, whereas the final gene product was observed at all intervals after inoculation. IL-6 was localized in the bony part of the bulla nearest to the mucosa, around mucosal vessels, and in the ciliae of the mucosal epithelium. The results demonstrated that IL-6 was synthesized locally as early as 1 h after bacterial middle ear challenge, and that although transcription could not be detected after 24 h, the cytokine product persisted for at least 5 days after the infection was introduced. CONCLUSIONS: IL-6 was shown to be produced early in the inflammatory process during induced pneumococcal otitis media in the rat. No production was seen after 24 h although the protein remained in the tissue for at least 5 days. IL-6 could initiate a differentiation of macrophages to osteoclasts and thereby participate in a bone remodeling process leading to tympanosclerosis development.

Blood culture bottles for transportation and recovery of anaerobic bacteria from non-blood samples.

Using bacterial suspensions as simulated non-blood specimens, the capacity of three different BacT/ Alert blood culture bottles for the transportation and recovery of anaerobic bacteria with different sensitivity to air was evaluated. To better assess the performance of the BacT/Alert bottles, three other liquid media specially designed for anaerobes were included in the study. Attention was paid to recovery rates in relation to species, initial bacterial concentration, and time needed for detection. Of the BacT/Alert blood culture bottles, the anaerobic FAN bottle yielded the highest recovery rates, but its performance was limited compared with chopped meat broth in tubes. This broth allowed detection of all the tested species within 48 h. Since collection and transportation of anaerobic bacteria are of major importance for a reliable culture result, improvements are necessary.

Experimental study of the virulence of Streptococcus pneumoniae with reduced susceptibility to penicillin.

Streptococcus pneumoniae is a major cause of morbidity and mortality in all age groups. In a few years, penicillin non-susceptible pneumococci (PNSP) have emerged worldwide as a new threat. In order to better understand the mechanisms behind the rapid expansion of these strains, the virulence of 10 clinical and two transformed PNSP strains were compared with the virulence of three fully susceptible strains in a mouse model of bacteremia and a rat model of acute otitis media. Serotype, antibiotic susceptibility, and to some extent also genetic profile and growth rate of the strains were investigated before inoculation. The animals were monitored for up to 7 days after challenge by clinical examinations/otomicroscopy and cultures from middle ears and blood. The results of the study demonstrated that the PNSP strains had a significantly reduced ability to persist at the infectious site, and to some extent also to induce infections, compared with fully susceptible strains. The reduction was most evident for strains isolated from sources other than blood. It is therefore possible that other factors than virulence factors are of importance for the ability of PNSP strains to expand.

Expression of cytokine genes during pneumococcal and nontypeable Haemophilus influenzae acute otitis media in the rat.

Acute otitis media (AOM) elicits potent inflammatory responses from the cells of the middle ear mucosa as well as from infiltrating leukocytes. To explore host responses during experimental AOM induced by Streptococcus pneumoniae type 3 and nontypeable Haemophilus influenzae (NTHi), otomicroscopy findings and expression of cytokine genes in the middle ear were monitored up to 1 month postinoculation. The mucosa and infiltrating cells responded rapidly to the bacterial challenge. Otomicroscopically, AOM appeared 1 day after NTHi inoculation and 3 days after pneumococcus inoculation. Pneumococcal AOM was more severe than NTHi otitis, but in general, lower transcript levels were detected in pneumococcus-infected than in NTHi-infected animals. Interleukin-6 (IL-6) mRNA levels peaked at 3 to 6 h for both pneumococcus-infected and NTHi-infected animals. IL-1alpha, tumor necrosis factor alpha, and IL-10 mRNA levels peaked at 6 h for NTHi otitis and 1 to 3 days for pneumococcal otitis. Comparing otomicroscopy with expression profiles, it would appear that the majority of cytokine mRNAs had passed their peak before the AOM diagnosis could be made clinically. Only transforming growth factor beta mRNA followed a slower time course, peaking very late and continuing expression even after the AOM was otomicroscopically resolved. IL-2 and IL-4 mRNAs were not detected in any animal at any time. Most of the investigated cytokines are very early markers for AOM and may be involved in initiation of inflammation, but they would be poor targets for pharmacological manipulation since their levels decline before clinical signs appear.

Moraxella catarrhalis-induced purulent otitis media in the rat middle ear. Structure, protection, and serum antibodies.

To study the effects of viable and heat-killed Moraxella catarrhalis bacteria on the middle ear mucosa and to evaluate the protection after whole-cell immunizations, Sprague-Dawley rats were challenged and rechallenged with four different M. catarrhalis strains. The animals were monitored by clinical observations, bacterial and histological samples from middle ears, and serum IgG levels. Only viable bacteria at a high concentration induced purulent otitis media, which was culture positive in 58% of the cases on day 4. The infection was characterized by a mild acute reaction lasting otomicroscopically about 8 days, together with quantitative and qualitative changes of the goblet cells. Structurally the mucosal effects of the heat-killed bacteria were less pronounced in the early phase compared to the viable bacteria, but similar at the end of the experiment at 6 months. The intrabullar and subcutaneous immunizations evoked an IgG antibody response in all animals, and the protection rate after immunization was 50% or more. The induced protection was not strain-specific. The study showed the rat to be a possible alternative for the study of different aspects of M. catarrhalis otitis media, an infection that is clinically and structurally different from that elicited by Streptococcus pneumoniae and Haemophilus influenzae in the rat.

Immunization and protection in pneumococcal otitis media studied in a rat model.

The recent and growing problem of bacterial resistance to common antibiotics has generated great interest in different methods for prevention of infections. The treatment of the pathogens causing upper airway infections and especially acute otitis media (AOM) is especially interesting in this context because these infections are a common cause of prescription of antibiotics all over the world. Both in AOM and recurrent AOM, Streptococcus pneumoniae, the most frequently occurring bacterium is isolated in 30-50% of all AOM attacks. In the last decade, multiresistant S. pneumoniae have emerged as a major problem. Thus, it is important to explore possibilities that immunization may protect against pneumococcal OM. In a well-defined animal model using Sprague-Dawley rats, we have investigated the effects of different routes of immunization with different antigens and whole cells. Together with otomicroscopical evaluation of middle ear (ME) status, samples for bacterial cultivation as well as for studies of histopathological changes have been collected. Antibody titers have been followed during and after pneumococcal AOM by an enzyme-linked immunosorbent assay (ELISA) method.

[Aminoglycoside-resistant enterococci a new bacterial hazard]. / Enterokocker resistenta mot aminoglykosider, nytt bakteriellt hot.

Enterococci are common causative agents in a broad range of human infections. Although formerly considered to be of low virulence, in recent years they have emerged as important pathogens, particularly in the hospital environment. Enterococci are not only intrinsically resistant to several antibiotics, but are also characterised by a potent and unique ability to exchange genetic material. With the increasing prevalence of strains resistant to ampicillin, aminoglycosides and glycopeptides, serious therapeutic difficulties have become more common. Epidemiological aspects, the mechanisms of action, the detection of antibiotic resistance, and the situation of enterococci in Sweden are discussed in the article.

[Infections and treatment of chronic leg ulcers: the use of antibiotics is too excessive, restrictive prescription is recommended]. / Infektioner och behandling vid kroniska bensår: antibiotikaförbrukningen alltför hög, restriktivitet förordas.

Chronic venous leg ulcers are contaminated or colonised with bacteria that seldom affects ulcer healing. Signs of clinical infection appear in only a minority of chronic ulcers. In spite of this, data show a high consumption of antibiotics in this group of patients. Treatment with antibiotics is indicated only when clinical signs of infection or obvious risk factors are present or when Streptococcus pyogenes is isolated from the ulcer. In these cases an oral antistaphylococcal agent (semisynthetic penicillinase-resistant penicillin or first generation oral cephalosporin) is recommended as the first choice. Enterococci, anaerobic bacteria and gram-negative bacteria including pseudomonas spp. often colonise chronic ulcers, but do not usually cause antibiotic requiring infection.