Roland Möllby - Academia.edu (original) (raw)

Papers by Roland Möllby

Fems Microbiology Letters, Aug 1, 2007

Aeromonas is a ubiquitous gram-negative bacterium that persists in the environment. It is shown t... more Aeromonas is a ubiquitous gram-negative bacterium that persists in the environment. It is shown that all isolates of persistent Aeromonas clones show strong biofilm formation ability. C-di-GMP regulates biofilm formation in many bacteria. To investigate the impact of c-di-GMP signaling, we introduced heterologous GGDEF and EAL domain proteins from Salmonella Typhimurium to an Aeromonas veronii biovar sobria strain. Overexpression of the GGDEF domain protein AdrA increased c-di-GMP concentration and biofilm formation and reduced motility. Production of the quorum-sensing signaling molecule C4-homoserine lactone and adhesion to aquatic plant duckweed and amoeba surfaces were enhanced. On the other hand, overexpression of the EAL domain protein YhjH decreased biofilm formation and increased motility.

Fems Microbiology Letters, Apr 1, 1979

Infection and Immunity, 1971

Staphylococcus aureus strain Smith 5R was found to produce a hemolysin with an isoelectric point ... more Staphylococcus aureus strain Smith 5R was found to produce a hemolysin with an isoelectric point of 9.5 and with a hemolytic spectrum different from alpha, beta, and delta hemolysins.

Infection and Immunity, 1989

A persistent vaginal colonization with a pyelonephritogenic strain of Escherichia coli, induced b... more A persistent vaginal colonization with a pyelonephritogenic strain of Escherichia coli, induced by administration of amoxicillin, was established in four adult cynomolgus monkeys. This colonization mimicked the one seen in urinary tract infection-prone human females. Attempts to eliminate the E. coli colonization and restore normal conditions were made. Either suspensions of lactobacilli or vaginal fluid from a healthy unmanipulated monkey was administered as repeated vaginal flushes for 5 to 9 days. A total elimination of vaginal E. coli was observed in two of six experiments with lactobacilli, and a decrease was observed in the other four. A better result was obtained with flushes of vaginal fluid, which eliminated the E. coli colonization in eight of eight experiments. In two of these, a single flush was sufficient to obtain a decolonization. The ability of fresh vaginal fluid to eliminate E. coli from the vagina could be transferred from one monkey to another. This study demonst...

Journal of Clinical Microbiology, 1988

Serum antibodies to purified pneumolysin were determined by enzyme-linked immunosorbent assay (EL... more Serum antibodies to purified pneumolysin were determined by enzyme-linked immunosorbent assay (ELISA) in paired samples from 406 adult patients with community-acquired pneumonia and in samples from 184 healthy controls. A high sensitivity (83%) was obtained in patients with blood culture-confirmed pneumococcal pneumonia. In patients with a tentative pneumococcal diagnosis based on culture of samples from the sputum or the nasopharynx, 45% were positive by ELISA. The difference likely reflected the different relevance of cultural findings for the diagnosis of pneumococcal pneumonia. A significant rise in ELISA titer was found in 17% of the patients. When the diagnosis was also based on high titers, 25% were positive. Pneumococcal pneumonia diagnosed by the pneumolysin ELISA was significantly more common in the patients with a more severe disease and who required hospitalization (21 versus 5% for outpatients). Younger patients were more often positive for pneumococci as determined by ...

Antimicrobial Agents and Chemotherapy, 2019

Antibiotic resistance in bacteria is an emerging problem globally. Resistant bacteria are found i... more Antibiotic resistance in bacteria is an emerging problem globally. Resistant bacteria are found in human and animal microbiota, as well as in the environment. Wastewater receives bacteria from all these sources and thus can provide a measurement of abundance and diversity of antibiotic-resistant bacteria circulating in communities. In this study, water samples were collected from a wastewater pump station in a Norwegian suburban community over a period of 15 months.

Journal of Water and Health, 2014

We describe a simple and standardised screening system (AREB) for surveillance of antibiotic resi... more We describe a simple and standardised screening system (AREB) for surveillance of antibiotic resistant bacteria in the environment. The system consists of 96 well microplates containing eight sets of breakpoint amounts of 10 different antibiotics. The incubated microplates are read by a desktop scanner and the plate images are analysed by special software that automatically presents the resistance data. The AREB method is combined with a rapid typing method, the PhenePlate system, which yields information on the diversity of the bacteria in the studied samples, and on the possible prevalence of resistant clones. In order to demonstrate the usage of AREB, a comparative study on the resistance situation among 970 Escherichia coli isolates from sewage and recipient water in Sweden, Norway and Chile, was performed. Resistance rates to all antibiotics were markedly higher in hospital sewage than in other samples. Our data indicate that the AREB system is useful for comparing resistance r...

The Lancet, 1982

severe, interstitial pneumonitis of undetermined cause. The remaining animals were anaesthetised,... more severe, interstitial pneumonitis of undetermined cause. The remaining animals were anaesthetised, systemically perfused with buffered solutions of paraformaldehyde followed by glutaraldehyde, and tissue prepared for examination in 1 m epoxy cross-sections stained with toluidine-blue. Examination of cortex, cerebellum, spinal cord, sciatic-nerve complex, and gastrocnemius muscle revealed no toxin-related pathological changes. Thus authentic samples of contaminated oil did not induce neuromuscular disease in a species that is sensitive to most neurotoxins. The relative doses were much larger than the amounts ingested by victims of the Spanish oil syndrome and the exposure was longer. These negative data, coupled with the absence of identified neurotoxic agents in the adulterated oil sample studied, strengthen the view that the neuromuscular sequelae of this disease are attributable to factors other than a direct-acting neurotoxin.

Journal of Infectious Diseases, 1985

The carrier rate of Clostridium difficile in an adult Swedish population was found to be 11 (1.9%... more The carrier rate of Clostridium difficile in an adult Swedish population was found to be 11 (1.9%) of 594. All isolates were toxigenic in vitro, but no healthy individual harbored free cytotoxin in stool. Of 398 patients with acute diarrhea not associated with antibiotic use, cytotoxin was found in stool filtrates of four (1%). In 4,793 patients with antibiotic-associated diarrhea from all parts of Sweden during 1980-1982, C. difficile cytotoxin was demonstrated in 873 (1807o). The tissue culture assay was found to be more specific than cultivation for the bacterium. By weighted analysis, in the age group >70 years more women than men were infected. In the age group 21-50 years there was an even greater preponderance of infection in women than in men. Cephalosporins and lincosamides were 10-70 times more often implicated in C. difficile colitis than were narrow-spectrum penicillins. Toxin-producing Clostridium difficile is a common bacterial isolate from patients with antibioticassociated diarrhea (AAD) and colitis (AAC). The bacterium seems to overgrow the normal bowel flora because of changes in the intestinal tract caused by antibiotics or other agents influencing the intestinal ecology. It is still uncertain whether the organism is endogenous or acquired mainly from exogenous sources before disease [1]. In children less than two years old C. difficile and its cytotoxin are commonly found without association to intestinal disease [2, 3], and both bacterium and cytotoxin have been demonstrated in adults with no signs of diarrhea or colitis [4]. Colitis due to C. difficile has been associated with most antimicrobial agentsin particular, aminopenicillins, cephalosporins, and lincosamides [5]. However, data are scarce regarding the actual risks related to the consumption of various antibiotics in a population.

Journal of Clinical Investigation, 1997

Clinical observations suggest that immune mechanisms affect etiology and course of recurrent cyst... more Clinical observations suggest that immune mechanisms affect etiology and course of recurrent cystitis. A primate infection model was used to show that primary bladder infection with a uropathogenic P-fimbriated strain (binding to globoside present in the bladder wall) protects against rechallenge with homologous as well as heterologous Escherichia coli strains for up to 5-6 mo. In contrast, mutant derivatives producing P-fimbriae either lacking the tip adhesin protein or carrying an adhesin for which no bladder receptor was present, were unable to induce protection, even though they generated bladder infections of similar duration as the wild type. Therefore, the protective effect mediated by the adhesin seemed to depend upon the presence of its cognate receptor. Since the wild strain also mediated protection against mutants that lacked the adhesin, our data suggest that the globoside-binding PapG adhesin acts as an adjuvant during infection to enhance a specific response against other bacterial antigens. In fact, the globoside-binding strain DS17, but not the mutant DS17-1, unable to bind to membrane-bound globoside, elicited a secretory IgA response to LPS in urine. These in vivo findings suggest that bacterial adhesin-ligand interactions may have signaling functions of importance for the immune response.

Journal of Biological Chemistry, 1996

Journal of Biological Chemistry, 1997

Journal of Bacteriology, 2003

The Escherichia coli BarA and UvrY proteins were recently demonstrated to constitute a novel two-... more The Escherichia coli BarA and UvrY proteins were recently demonstrated to constitute a novel two-component system, although its function has remained largely elusive. Here we show that mutations in the sensor kinase gene, barA , or the response regulator gene, uvrY , in uropathogenic E. coli drastically affect survival in long-term competition cultures. Using media with gluconeogenic carbon sources, the mutants have a clear growth advantage when competing with the wild type, but using media with carbon sources feeding into the glycolysis leads to a clear growth advantage for the wild type. Results from competitions with mutants in the carbon storage regulation system, CsrA/B, known to be a master switch between glycolysis and gluconeogenesis, led us to propose that the BarA-UvrY two-component system controls the Csr system. Taking these results together, we propose the BarA-UvrY two-component system is crucial for efficient adaptation between different metabolic pathways, an essenti...

Food & Nutrition Research, 2004

FEMS Microbiology Letters, 1981

FEMS Microbiology Letters, 1979

Applied and Environmental Microbiology, 2002

In Europe the use of the growth promoter avoparcin is considered to have selected for vancomycin-... more In Europe the use of the growth promoter avoparcin is considered to have selected for vancomycin-resistant enterococci (VRE). Sweden ceased using avoparcin in 1986, and only occasional cases of VRE from hospitals have been reported since 1995. Within the framework of a European study, samples from urban raw sewage, treated sewage, surface water, and hospital sewage in Sweden ( n = 118) were screened for VRE. Surprisingly, VRE were isolated from 21 of 35 untreated sewage samples (60%), from 5 of 14 hospital sewage samples (36%), from 6 of 32 treated sewage samples (19%), and from 1 of 37 surface water samples. Thirty-five isolates from 33 samples were further characterized by geno- and phenotyping, MIC determination, and PCR analysis. Most isolates (30 of 35) carried the vanA gene, and the majority (24 of 35) of the isolates were Enterococcus faecium . Most of the VRE were multiresistant. The typing revealed high diversity of the isolates. However, one major cluster with seven identi...

Applied and Environmental Microbiology, 2004

We describe the ScanMIC method, a colorimetric MIC method for susceptibility testing of gram-nega... more We describe the ScanMIC method, a colorimetric MIC method for susceptibility testing of gram-negative fermentative bacteria. The method is a slight modification of the National Committee for Clinical Laboratory Standards (NCCLS) recommended broth microdilution method that uses a redox indicator 2,3,5-triphenyltetrazolium chloride (TTC) to enhance the estimate of bacterial growth inhibition in a microplate and a flatbed scanner to capture the microplate image. In-house software was developed to transform the microplate image into numerical values based on the amount of bacterial growth and to generate the MICs automatically. The choice of indicator was based on its low toxicity and ease of reading by scanner. We compared the ScanMIC method to the NCCLS recommended broth microdilution method with 197 coliform strains against seven antibacterial agents. The interpretative categorical agreement was obtained in 92.4% of the assays, and the agreement for MIC differences (within ±1 log 2 d...

Analytica Chimica Acta, 2003

We have developed a multi-species microbial assay, MARA, for assessing the (eco)toxic risks of ch... more We have developed a multi-species microbial assay, MARA, for assessing the (eco)toxic risks of chemical compounds and for the determination of their toxic fingerprints. The main advantages with MARA are (1) the simultaneous testing on several microbial strains; (2) the concept of toxic fingerprinting; (3) the simple and inexpensive handling and reading of the test. The toxic activity is measured in parallel on 11 different microorganisms lyophilised in a microplate. A concentration gradient of the chemical to be tested is added and growth is indicated through the reduction of tetrazolium red (TTC). The microplates are read by a common flatbed scanner or a microplate spectrophotometer. The array of the 11 different inhibition values constitute a toxic fingerprint, characteristic for each type of chemical compound, and it is shown that the assay can distinguish between 12 standard chemicals. Both the reproducibility (CV ≈ 20%) and the sensitivity are similar to other toxicity tests based on microorganisms .