Erwinia species: an emerging human pathogen

Study of antibiotic resistance in freshwater ecosystems with low anthropogenic impact

This study aimed to investigate the bacterial diversity and the background level of antibiotic resistance in two freshwater ecosystems with low anthropogenic impact in order to evaluate the presence of natural antimicrobial resistance in these areas and its potential to spread downstream. Water samples from a pre-Alpine and an Apennine river (Variola and Tiber, respectively) were collected in three different sampling campaigns and bacterial diversity was assessed by 16S sequencing, while the presence of bacteria resistant to five antibiotics was screened using a culturable approach. Overall bacterial load was higher in the Tiber River compared with the Variola River. Furthermore, the study revealed the presence of resistant bacteria, especially the Tiber River showed, for each sampling, the presence of resistance to all antibiotics tested, while for the Variola River, the detected resistance was variable, comprising two or more antibiotics. Screening of two resistance genes on a total of one hundred eighteen bacterial isolates from the two rivers showed that bla_TEM, conferring resistance to β-lactam antibiotics, was dominant and present in ~58 % of isolates compared to only ~9 % for mefA/E conferring resistance to macrolides. Moreover, β-lactam resistance was detected in various isolates showing also resistance to additional antibiotics such as macrolides, aminoglycosides and tetracyclines. These observations would suggest the presence of co-resistant bacteria even in non-anthropogenic environments and this resistance may spread from the environment to humans and/or animals.

Pantoea in Peritoneal Dialysis: A Rare Cause of Peritonitis

Peritonitis is the most common complication of peritoneal dialysis (PD) and an important cause of PD failure. There are numerous etiological agents, mostly bacteria. Pantoea spp is a rare cause of peritonitis.

We describe three cases of Pantoea peritonitis in three PD patients. Previous reports have identified risk factors such as close contact with plants and animals. We review the typical clinical presentation and prognosis. It is fulcral to teach patients about the risks regarding proximity to plants and animals to prevent this type of infection.

Subchronic (90-day) toxicity assessment of Somacy-FP100, a lipopolysaccharide-containing fermented wheat flour extract from Pantoea agglomerans

Pantoea agglomerans is a Gram-negative bacterium that is ubiquitous in the environment, colonizing animals, humans, and numerous plants, including cotton and wheat. A lipopolysaccharide-containing fermented wheat flour extract from P. agglomerans (Somacy-FP100) is proposed for use as a food ingredient for individuals seeking foods for healthy aging. Previously published genotoxicity studies with Somacy-FP100 reported its lack of genotoxicity in vitro, but a subchronic toxicity study has not yet been performed. Therefore, to demonstrate the safety of Somacy-FP100 for use as a food ingredient, a 90-day oral (gavage) toxicity study in rats was conducted. Male and female Han Wistar rats were administered vehicle (control) or Somacy-FP100 at 500, 1500, or 4500 mg/kg body weight/day at a dose volume of 10 mL/kg body weight, for at least 90 days. No test article-related adverse clinical signs or effects on body weight, food consumption, or clinical pathology were observed, and there were no macroscopic or microscopic findings related to the test article. Therefore, 4500 mg/kg body weight/day (the highest dose tested and highest feasible dose) was established as the no-observed-adverse-effect level. This absence of subchronic toxicity, in addition to the previously reported lack of genotoxicity, demonstrates the safety of Somacy-FP100 for use as a food ingredient.

Pantoea peritonitis in a patient receiving chronic ambulatory peritoneal dialysis

Pantoea agglomerans is usually the most common organism transmitted through plant thorn injuries. This report is of a female patient maintained on chronic ambulatory peritoneal dialysis (CAPD) who developed peritonitis attributed to P. agglomerans. Peritonitis is an uncommon complication of P. agglomerans and there is no previous report of peritonitis associated with this organism in a CAPD patient. The source of infection was thought to be due to rose-thorn injury. Antibiotic therapy with ceftazidime and amikacin i.p. led to a clinical improvement, with disappearance of the organism in the peritoneal fluid.

Cross-species infections and their analysis

The ability of certain pathogens to infect multiple hosts has led to the development of genetically tractable nonvertebrate hosts to elucidate the molecular mechanisms of interactions between these pathogens and their hosts. The use of plant, insect, nematode, and protozoan hosts to study human pathogens has facilitated the elucidation of molecular nature of pathogenesis and host responses. Analyses of virulence of multihost pathogens on their respective hosts revealed that pathogens utilize many universal offensive strategies to overcome host defenses, irrespective of the evolutionary lineage of the host. Likewise, genetic dissections of the defense response of the nonvertebrate hosts have also shown that key features underlying host defense responses are highly conserved. This review summarizes how the information gained from the analysis of cross-species infections contributes to our understanding of host-pathogen interactions.

Hospital infestation by the cluster fly, Pollenia rudis sensu stricto Fabricius 1794 (Diptera: Calliphoridae), and its possible role in transmission of bacterial pathogens in Germany

The potential of the cluster fly, Pollenia rudis sensu stricto, to transmit bacterial pathogens was investigated during a mass infestation that took place in a German hospital. Cluster flies were individually examined for mesophilic bacteria carried on the exoskeleton. Bacterial growth could only be detected by using the enrichment culture technique to increase sensitivity, but not by direct intoculation of fly samples to agar plates. All 50 cluster fly samples that were tested carried opportunistic aerobic mesophilic Bacillus spp., whereas 41 fly samples were positive for Erwinia spp., 16 samples for Erwinia amylovara, 24 samples for Stenotrophomonas maltophilia, and 4 samples for Flavobacterium odoratum. Staphylococcus lugdunensis and Pseudomonas aeruginosa were found in 5 samples. No bacteriologically sterile cluster fly samples were obtained. The whole bacterial pattern found on P. rudis s. s. is known for its potential to cause opportunistic and/or nosocomial infections in humans. The results obtained led to the assumption that mass infestations of cluster flies occurring in sensitive areas, especially in hospitals, may cause a low, but not neglectable health threat due to mechanical transmission of bacterial pathogens.

Common mechanisms for pathogens of plants and animals

The vast evolutionary gulf between plants and animals--in terms of structure, composition, and many environmental factors--would seem to preclude the possibility that these organisms could act as receptive hosts to the same microorganism. However, some pathogens are capable of establishing themselves and thriving in members of both the plant and animal kingdoms. The identification of functionally conserved virulence mechanisms required to infect hosts of divergent evolutionary origins demonstrates the remarkable conservation in some of the underlying virulence mechanisms of pathogenesis and is changing researchers' thinking about the evolution of microbial pathogenesis.

Transfusion associated bacteremia and septic shock due to Erwinia herbicola

We report a case of severe septicemia after blood transfusion to a 61-year-old man. The patient developed septic shock with signs of disseminated intravascular coagulation already during the blood transfusion. Blood culture from the patient showed growth of Erwinia herbicola and culture from the blood bag massive growth of the same microorganism. The bag had been stored in a refrigerator for 3 weeks after tapping. It is likely that contamination occurred during the tapping procedure.

Exposure to dust-borne bacteria in agriculture. I. Environmental studies

In order to evaluate the exposure of agricultural workers to dust-borne bacteria, microbiological examinations of the air were performed in grain storing and processing plants and in animal houses. Large concentrations of viable microorganisms, ranging from 129.2 to 1289.9 thousands/m3 of air, were found in the rooms contaminated with grain dust and much lower in those contaminated with flour dust (22.6 thousands/m3). Bacteria predominated in the air of grain plants, whereas actinomycetes and fungi were less numerous. The most abundant bacteria were Gram negative rods of the species Erwinia herbicola. Large concentrations of air-borne microorganisms were also found in different animal farms, reaching 225.5 to 595.4 thousands/m3 in hatcheries and 7751.5 thousands/m3 in a broiler house. Staphylococci were most frequently isolated and other common organisms were Corynebacteria and Streptococci. It was concluded that high exposure to dust-borne bacteria creates a hazard to agricultural workers.

Traumatic endophthalmitis caused by an Erwinia species

A previously healthy 70-year-old white man sustained a plant injury to his left eye while gardening and was admitted here because of an ensuing perforated cornea and endophthalmitis. The lens was opaque and its anterior capsule was ruptured. Culture of fluid obtained by anterior chamber paracentesis yielded a species of the Erwinia herbicolalathyri group (Enterobacter agglomerans). Thirty-seven days after a course of cefazolin and gentamicin therapy, corneal edema necessitated a planned extracapsular cataract extraction. The aqueous humor and lens again revealed the identical Erwinia species in pure culture. The patient received another course of cefazolin and showed improvement after the lens aspiration.

Transmission of lac by the sex factor E in Erwinia strains from human clinical sources

Lactose-utilizing (Lac(+)) strains of Erwinia spp. from human clinical material transfer lac by conjugation to plant strains of Erwinia herbicola and Erwinia amylovora, to other Erwinia strains from human clinical sources, and also to Escherichia coli, Paracolobactrum arizonae, Salmonella typhimurium, and Shigella dysenteriae. The frequency of this transfer varies with the donor and recipient strains employed. The lac genes appear stable in these exconjugants, and they are not cured by acridine orange. The Lac(+) exconjugants transfer lac to an Escherichia coli F(-) Lac(-) strain; the frequency of this transfer is high with E. herbicola and S. typhimurium exconjugants and relatively low with other exconjugants. The most studied Erwinia donor strain from human clinical material (EH133) and its Lac(+) exconjugants are insensitive to the F-specific phage, M13. P1-mediated transduction of lac, by using a Lac(+) exconjugant of E. coli as the donor and an E. coli F(-) Lac(-) strain as the recipient, revealed that all 50 Lac(+) transduced clones tested also inherited donor ability, suggesting a close linkage between the Erwinia sex factor (designated as E) and the lac genes. The E. coli culture harboring E-lac (E and the lac genes linked to it) does not restrict phages T1, T7, and lambdavir. E-lac is compatible with F'his, R100 drd-56 (F-like), and R64 drd-11 (I-like); cells harboring F'his or one of the R factors do not show super-infection immunity to the incoming E-lac, and E-lac plus one of the other plasmids can coexist stably in the same cell. The fertility of cells harboring F'his or R100 drd-56-as determined by the frequency of conjugal transfer of his or of the resistance determinant (Tet(r) in case of R100 drd-56) and also by sensitivity to F-specific phage (M13)-is not altered by the presence of E-lac, and this suggests that the sex factor E might belong to the fi(-) class.