Indwelling device-related and recurrent infections due to Aeromonas species

Multidrug-resistant aeromonas caviae causing cystitis in a renal failure patient

A 49-year-old female with multiple myeloma complicated by renal failure had dysuria. The urine culture revealed multidrug-resistant aeromonas caviae during her hospital stay. Her symptoms and signs significantly improved after receiving a seven-day course of piperacillin-tazobactam treatment. She had no history of urinary tract infections(UTIs). On follow-up, she felt clinically well. Aeromonas caviae is a rare cause of UTI. We review previous cases of aeromonas caviae UTIs. The purpose of this case report is to assist in the diagnosis and management of aeromonas caviae cystitis.

Plasmid-Mediated Fluoroquinolone Resistance Genes in Quinolone-Susceptible Aeromonas spp. Phenotypes Isolated From Recreational Surface Freshwater Reservoir

Aeromonas spp. are recognized as opportunistic pathogens causing diseases. Infections in humans can result mainly in gastrointestinal and wound diseases with or without progression to septicemia. Although Aeromonas spp. are not known uropathogens and they rarely cause urinary tract infection, we hypothesize that the presence of these bacteria in the water and the contact during, e.g., recreational and bathing activity can create the conditions for the colonization of the human body and may result to diseases in various locations, including the urinary tract. Our study presents the occurrence of aeromonad fluoroquinolone-susceptible phenotypes with the presence of plasmid-mediated fluoroquinolone resistance (PMQR) genes in a natural freshwater reservoir occasionally used for recreational activities. Sixty-nine isolates collected during the bathing period were identified by mass spectrometry and screened for the presence of fluoroquinolone-resistant phenotypes and genotypes. Fluoroquinolone susceptibility was determined as minimal inhibitory concentration values. PMQR qnr genes were detected by PCR. Isolates comprising eight species, namely, mainly Aeromonas veronii (50.7% isolates) and Aeromonas media (24.6% isolates) and rarely Aeromonas eucrenophila, Aeromonas caviae, Aeromonas bestiarum, Aeromonas ichthiosmia, and Aeromonas hydrophila, were selected. All isolates were phenotypically susceptible either to ciprofloxacin or levofloxacin. Unexpectedly, at least one to three of the PMQR genes were detected in 42.0% of the fluoroquinolone-susceptible Aeromonas spp. phenotypes. Mainly the qnrS (34.8% isolates) and qnrA (14.5% isolates) determinants were detected. In conclusion, the freshwater reservoir occasionally used for bathing was tainted with aeromonads, with a high occurrence of opportunistic pathogens such as A. veronii and A. media. MALDI‐TOF MS is a powerful technique for aeromonad identification. Our data reveals the mismatch phenomenon between fluoroquinolone-susceptible aeromonad phenotypes and the presence of plasmid-mediated qnr resistance genes. It suggests that phenotypically susceptible bacteria might be a potential source for the storage and transmission of these genes. The exposure during, e.g., a recreational activity may create the potential risk for causing infections, both diagnostically and therapeutically difficult, after expressing the resistance genes and quinolone-resistant strain selection.

Urinary tract infection due to Aeromonas species: An uncommon causative agent

BACKGROUND

Members of the genus Aeromonas are Gram-negative bacilli, belonging to family Aeromonadaceae, and are widely found in various aquatic environments. The most common species associated with human infections are A. hydrophila, A. caviae, and A. veronii biovar sobria. Aeromonas species are recognized as emerging opportunistic pathogens in humans mainly causing gastrointestinal infections and wound infections with or without progression to septicaemia. Aeromonas organisms rarely cause urinary tract infection (UTI) and are not known uropathogens.

CASE

We report a series of UTI due to Aeromonas species in three adult patients, specifically identified as A. veronii biovar sobria in two patients and A. hydrophila in one patient. Two patients had history of occupational exposure to aquatic environment.

CONCLUSIONS

The cases highlight another expanded range of infections caused by Aeromonas spp. that can be encountered in a community setting and indicate that infections with Aeromonas spp. should be kept in mind while investigating for the etiology of UTI, especially in adult patients with occupational exposure to aquatic ecosystems.

Bacteriological, Clinical and Virulence Aspects of Aeromonas-associated Diseases in Humans

Aeromonads have been isolated from varied environmental sources such as polluted and drinking water, as well as from tissues and body fluids of cold and warm-blooded animals. A phenotypically and genotypically heterogenous bacteria, aeromonads can be successfully identified by ribotyping and/or by analysing gyrB gene sequence, apart from classical biochemical characterization. Aeromonads are known to cause scepticemia in aquatic organisms, gastroenteritis and extraintestinal diseases such as scepticemia, skin, eye, wound and respiratory tract infections in humans. Several virulence and antibiotic resistance genes have been identified and isolated from this group, which if present in their mobile genetic elements, may be horizontally transferred to other naive environmental bacteria posing threat to the society. The extensive and indiscriminate use of antibiotics has given rise to many resistant varieties of bacteria. Multidrug resistance genes, such as NDM1, have been identified in this group of bacteria which is of serious health concern. Therefore, it is important to understand how antibiotic resistance develops and spreads in order to undertake preventive measures. It is also necessary to search and map putative virulence genes of Aeromonas for fighting the diseases caused by them. This review encompasses current knowledge of bacteriological, environmental, clinical and virulence aspects of the Aeromonas group and related diseases in humans and other animals of human concern.

Aeromonas veronii biovar veronii and sepsis-infrequent complication of biliary drainage placement: A case report

BACKGROUND

Aeromonas species are uncommon pathogens in biliary sepsis and cause substantial mortality in patients with impaired hepatobiliary function. Asia has the highest incidence of infection from Aeromonas, whereas cases in the west are rare.

CASE SUMMARY

We report the case of a 64-year-old woman with advanced pancreatic cancer and jaundice who manifested fever, abdominal pain, severe thrombocytopenia, anemia and kidney failure following the insertion of a percutaneous transhepatic biliary drainage. Blood culture results revealed the presence of Aeromonas veronii biovar veronii (A. veronii biovar veronii). After antibiotic therapy and transfusions, the life-threatening clinical conditions of the patient improved and she was discharged.

CONCLUSION

This was a rare case of infection, probably the first to be reported in West countries, caused by A. veronii biovar veronii following biliary drainage. A finding of Aeromonas must alert clinician to the possibility of severe sepsis.

Bone graft donor site infection with a rare organism, Aeromonas Hydrophila. A typical location, presentation and organism with 2 years follow-up. Case report

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A. Hydrophila found in immunocompromised patients, burns or aquatic trauma patients.

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Aeromonas produce β-lactamase making it resistant to usual prophylactic antibiotics.

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Early surgical and antibiotic treatment is essential.

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Following a multidisciplinary approach, these patients avoid catastrophic results.

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Combined case report with detailed review of A. Hydrophila from recent literature.

Introduction

Aeromonas are Gram-negative bacilli often causing necrotizing fasciitis or sepsis in immunocompromised patients. Aeromonas Hydrophila is most often found in immunocompromised patients or those with burns or aquatic trauma. When patients present with a discharge and infection on bone graft donor site and progressive sepsis, an Aeromonas hydrophila infection should be considered in the differential diagnosis.

Presentation of case

We report here a rare case of Aeromonas hydrophila with surgical site sepsis/infection in an immunocompromised 69 years old female, with several comorbids. Here we are reporting infection on donor surgical graft site, sparing major surgical site with the implant. After getting culture report of exudates from the wound that grew A. hydrophila, immediate wound debridement and antibiotic beads insertion was performed with appropriate antimicrobial therapy and regular wound dressing. She was followed for around 2 years.

Discussion

This is the first report to our knowledge of A. Hydrophila infection in bone graft donor site. Aeromonas most often cause gastrointestinal and soft tissue infections, and bacteremia in immunocompromised patients. Early surgical intervention is essential to reducing mortality in deep soft tissue infections caused by this organism. Aeromonas have shown resistance to penicillin but are sensitive to other broad-spectrum antibiotics.

Conclusion

Early suspicion, diagnosis, and treatment with potent antibiotics are needed to prevent any further complications resulting from infection by this emerging aggressive pathogen.

Clinical significance and outcome of Aeromonas spp. infections among 204 adult patients

The objectives of this investigation were to analyze the clinical patterns, risk groups, prognostic factors, and mortality of infections caused by Aeromonas spp. This was a retrospective study of adult patients with Aeromonas spp. isolates attended at the Hospital del Mar in Barcelona, Spain, between January 2006 and December 2012. Epidemiological data, antimicrobial susceptibility, clinical patterns, underlying illnesses, type of infection, admission to the intensive care unit (ICU), number of episodes, coinfection, antimicrobial therapy, and evolution were analyzed. A total of 221 clinical samples from 204 patients were positive for Aeromonas spp. The mean age of the patients was 67.6 years. The main clinical form of presentation was gastrointestinal (78.4%). Malignancy was the main risk group in 69 (33.8%) patients, and 48 (23.5%) were previously healthy. Twenty-one patients (10.3%) were admitted to the ICU. Infections were acquired in the hospital in 52.5% of the patients, and 28.9% were polymicrobial. The overall mortality (after 1 year of follow-up from the first positive culture) was 26.5%. Univariate analysis identified an association between increased mortality and the following variables: age ≥80 years, hospitalization, admission to the ICU, malignancy, extraintestinal infection, and appropriate antimicrobial therapy. In the multivariate analysis, age ≥80 years [odds ratio (OR), 4.37 [95% confidence interval (CI), 1.68-11.35; p = 0.002]], admission to the ICU (OR, 6.59 [95% CI, 2.17-19.99; p = 0.001]), and malignancy (OR, 3.62 [95% CI, 1.32-9.90; p = 0.012]) were significantly associated with mortality. Aeromonas infections are mainly gastrointestinal. The 1-year follow-up mortality rate was high. Old age (age ≥80 years), admission to the ICU, and malignancy were identified as independent risk factors for mortality.

Unusual microorganisms and antimicrobial resistances in a group of Syrian migrants: Sentinel surveillance data from an asylum seekers centre in Italy

BACKGROUND

Three years of civil war in Syria have caused death and increase of communicable diseases. The suffering population has been forced to migrate creating a fertile condition for epidemic spread of infection within the refugee camps.

METHODS

Forty-eight Syrian migrants, upon their arrival in Italy, were accommodated at the asylum seekers centre of Castelnuovo di Porto. They received a physical examination and were subjected to microbiological surveillance by blood, rectal, pharyngeal and nasal swabs collection and delivering to the Clinical Pathology and Microbiology Laboratory of the University Campus Bio-Medico of Rome.

RESULTS

All refugees resulted negative for HBV, HCV and HIV infections. In swabs a large number of unusual gram-negative bacteria species were isolated, such as Pseudomonas putida, Pseudomonas monteilii, Pseudomonas fulva, Pseudomonas moselii, Aeromonas veronii, Aeromonas caviae, Aeromonas hydrophila, Acinteobacter guilloviae, Acinteobacter lowffii; Acinetobacter johnsonii; Acinteobacter tjernbergae; Pantoea agglomerans; Pantoea calida. Among isolates, strains resistant to carbapenems, ESBL producers and methicillin resistant were found.

CONCLUSIONS

The microbiological surveillance performed represents a useful action to understand refugees health status and to trace unusual microorganisms movement even carriers of antimicrobial resistance during migrants traveling.

Mortality of therapeutic fish Garra rufa caused by Aeromonas sobria

OBJECTIVE

To investigate a case of mass mortality of Garra rufa (G. rufa) from a fish hatchery farm in Slovakia.

METHODS

Causative bacterial agent was swabbing out of affected fish skin area and subsequently identified using commercial test system. Antibiotic susceptibility was determined by the disk diffusion method.

RESULTS

Infected G. rufa was characterized by abnormal swimming behaviour, bleeding of skin lesions and local haemorrhages. Despite of using recommended aquatic antibiotic treatment no improvement was achieved and Aeromonas sobria (A. sobria) was identified as a causative agent of fish mortality. Due to massive fish mortality, antibiotic susceptibility of pure isolated culture of A. sobria was evaluated employing eight antibiotics against human infections. A. sobria was resistant only against one antibiotic, namely ampicilin.

CONCLUSIONS

These results indicate that A. sobria can act as a primary pathogen of G. rufa and may be a potential risk factor for immunodeficient or immunoincompetent patients during the ichthyotherapy.

Bacterial Strain Diversity Within Wounds

Significance: Rare bacterial taxa (taxa of low relative frequency) are numerous and ubiquitous in virtually any sample-including wound samples. In addition, even the high-frequency genera and species contain multiple strains. These strains, individually, are each only a small fraction of the total bacterial population. Against the view that wounds contain relatively few kinds of bacteria, this newly recognized diversity implies a relatively high rate of migration into the wound and the potential for diversification during infection. Understanding the biological and medical importance of these numerous taxa is an important new element of wound microbiology. Recent Advances: Only recently have these numerous strains been discovered; the technology to detect, identify, and characterize them is still in its infancy. Multiple strains of both gram-negative and gram-positive bacteria have been found in a single wound. In the few cases studied, the distribution of the bacteria suggests microhabitats and biological interactions. Critical Issues: The distribution of the strains, their phenotypic diversity, and their interactions are still largely uncharacterized. The technologies to investigate this level of genomic detail are still developing and have not been largely deployed to investigate wounds. Future Directions: As advanced metagenomics, single-cell genomics, and advanced microscopy develop, the study of wound microbiology will better address the complex interplay of numerous individually rare strains with both the host and each other.

Fatal Necrotizing Soft Tissue Infection by Aeromonas hydrophila

Aeromonas infections in healthy individuals are self limiting, but those in patients with immuno-compromised conditions are frequently associated with significant morbidity and mortality. The current case report describes a fatal case of necrotizing soft tissue infection by Aeromonas hydrophila in an immuno-competent patient.

Fulminant necrotizing fasciitis caused by Aeromonas sobria in neutropenic patients

Infection with Aeromonas species has been reported to occur in neutropenic patients. Necrotizing fasciitis caused by Aeromonas species is uncommon but potentially life-threatening. We herein describe three cases of fulminant necrotizing fasciitis caused by Aeromonas sobria in neutropenic patients. These cases shared many clinical characteristics, including shock, coagulopathy, multiple organ failure and rapidly deteriorating and eventually fatal clinical courses. In all cases, Aeromonas sobria was resistant to most antibiotics, except quinolones. Our experience suggests that necrotizing fasciitis caused by Aeromonas sobria is a distinctive and fatal entity. As the use of quinolones is not usually considered in cases of febrile neutropenia, it is important to adjust the antibiotics in time when culture results become available. In some cases, early treatment with quinolones and surgical intervention should be considered, especially when this complication occurs in patients with profound neutropenia.

The genus Aeromonas: taxonomy, pathogenicity, and infection

Over the past decade, the genus Aeromonas has undergone a number of significant changes of practical importance to clinical microbiologists and scientists alike. In parallel with the molecular revolution in microbiology, several new species have been identified on a phylogenetic basis, and the genome of the type species, A. hydrophila ATCC 7966, has been sequenced. In addition to established disease associations, Aeromonas has been shown to be a significant cause of infections associated with natural disasters (hurricanes, tsunamis, and earthquakes) and has been linked to emerging or new illnesses, including near-drowning events, prostatitis, and hemolytic-uremic syndrome. Despite these achievements, issues still remain regarding the role that Aeromonas plays in bacterial gastroenteritis, the extent to which species identification should be attempted in the clinical laboratory, and laboratory reporting of test results from contaminated body sites containing aeromonads. This article provides an extensive review of these topics, in addition to others, such as taxonomic issues, microbial pathogenicity, and antimicrobial resistance markers.

Case reports: fatal necrotizing fasciitis caused by Aeromonas sobria in two diabetic patients

We report two rare cases of Aeromonas sobria necrotizing fasciitis with sepsis in patients with diabetes. In both cases, immediate fasciotomy was performed and appropriate empiric antimicrobial therapy and intensive care were administered. However, the two patients died on Day 2 and Day 11, respectively, after admission as a result of multiple organ failure. When patients present with a rapid onset of skin necrosis and progressive sepsis, an Aeromonas sobria infection or Vibrio infection should be considered in the differential diagnosis.

Cystitis caused by Aeromonas caviae

Aeromonas sp. organisms rarely cause urinary tract infection. We report for the first time a case of urinary tract infection caused by A. caviae in an adult patient with a history of increased frequency of urination, dysuria, hematuria, and weight loss.

Clinical significance and distribution of putative virulence markers of 116 consecutive clinical Aeromonas isolates in southern Taiwan

OBJECTIVES

The objectives of this study were to elucidate the clinical manifestations of Aeromonas infections and the association of putative virulence genes with clinical invasiveness.

METHODS

116 consecutive clinical Aeromonas isolates collected from July 1999 to June 2001 in a medical center in southern Taiwan were included. All isolates were identified by biochemical phenotyping and their genomic sequences encoding eight putative virulence factors, including cytolytic enterotoxin (AHCYTOEN), aerolysin (aerA), hemolysin (hlyA), heat-labile enterotoxin (alt), heat-stable enterotoxin (ast), and components of type III secretion system (ascV, aexT and ascF-ascG) were analyzed using polymerase chain reaction and colony blot hybridization. The association of clinical diseases of the patients with the putative virulence genes in the isolates was analyzed.

RESULTS

Sixty-two percent of Aeromonas isolates caused clinically evident infections, of which the major clinical manifestations were primary bacteremia (40%), followed by soft tissue infections (27%), and hepatobiliary tract infections (15%). Liver cirrhosis (36%), malignancy (25%), and hepatobiliary diseases (13%) were the major underlying diseases in patients with Aeromonas bacteremia. The majority (64%) of patients with Aeromonas hepatobiliary infections had underlying hepatobiliary diseases, whereas 71% of those with soft tissue infections had antecedent water- or soil-related injuries. The crude fatality rate for Aeromonas infections was 26%. Aeromonas hydrophila complex was the most common (52%) of the three major complex groups investigated, followed by Aeromonas sobria complex (24%) and Aeromonas caviae complex (23%). None of the eight putative virulence factors was associated with invasiveness or bacteremia.

CONCLUSIONS

Primary bacteremia, soft tissue infections, and hepatobiliary tract infections are the three major clinical manifestations of invasive Aeromonas infections in southern Taiwan. This study found no association between the presence of AHCYTOEN, aerA, hlyA, alt, ast, ascV, aexT or ascF-ascG genes in Aeromonas isolates and the development of extra-intestinal infections or bacteremia.

Aeromonas popoffii urinary tract infection

Aeromonas popoffii is a recently described species isolated mainly from freshwater. An isolate of Aeromonas popoffii was found to be responsible for a urinary tract infection in a 13-year-old boy suffering from spina bifida with enterocystoplasty. This is the first reported case of human infection attributed to this species.

Adhesive properties of a LamB-like outer-membrane protein and its contribution to Aeromonas veronii adhesion

AIMS

To identify and characterize nonfimbrial proteins from Aeromonas veronii involved in the attachment to epithelial cells in vitro.

METHODS AND RESULTS

Two Aer. veronii mucin- and lactoferrin-binding proteins with molecular masses of 37 and 48 kDa were identified by Western blot analysis. According to its N-terminal amino acid sequence, the 48-kDa protein was identified as Omp48, an outer-membrane protein similar to LamB of Escherichia coli. LamB is a well-known porin involved in maltose transport across the outer membrane in E. coli. In a microtitre plate assay, Omp48 bound to the immobilized extracellular matrix proteins collagen and fibronectin, and the mucin- and lactoferrin-binding activity was confirmed. Adhesion of Omp48 to mucin, lactoferrin and collagen was diminished by preincubation with homologous glycoproteins or other carbohydrates, suggesting a putative Omp48 lectin-like binding domain. Anti-Omp48 antiserum significantly inhibited the Aer. veronii adhesion to confluent HeLa cell monolayers and pretreatment of cells with purified Omp48 elicited competitive inhibition of adhesion. Similarly, cross-inhibition of Aer. hydrophila and Aer. caviae adhesion was achieved with the same treatments, indicating the existence of a conserved surface protein among these species.

CONCLUSIONS

Taken together, these data indicate that Omp48 is involved in Aer. veronii adhesion to epithelial cells and might be an alternative adhesion factor of this micro-organism.

SIGNIFICANCE AND IMPACT OF THE STUDY

The adhesive potential of Aeromonas spp. is correlated with pathogenicity; however, the adhesion mechanism is complex and not well understood. This study provides evidence of a putative adhesion factor that might be contributing to pathogenicity of Aer. veronii and could be used for vaccine development.

Aeromonas infection of the hepatobiliary system: report of 15 cases and review of the literature

Aeromonas species cause both intestinal and extraintestinal disease. We reviewed hospital laboratory and medical records to identify patients with Aeromonas infection of the hepatobiliary or pancreatic system. Analysis of data from our hospital, as well as a review of the published literature, yielded a total of 41 episodes in 39 patients, and the features of these episodes are described. The most common manifestation of Aeromonas hepatobiliary infection among all reported cases was cholangitis (29 of 41 episodes). The majority of infections in our hospital occurred in patients with underlying immunosuppression or malignancy (13 of 15 patients), including 4 liver transplant recipients, and nosocomial infection was not infrequent (8 of 17 episodes). Infection occurred most commonly in patients with obstruction of the biliary tract due to stones, tumor, or stricture and was associated with a relatively high mortality rate (11.8%). Antibiotic susceptibility testing revealed that gentamicin, imipenem, and ciprofloxacin had the highest activity against the Aeromonas species isolated.

Aeromonas veronii biovar veronii septicaemia and acute suppurative cholangitis in a patient with hepatitis B

Gram-negative bacilli of the genus Aeromonas are widespread in aquatic environments and can be responsible for human infections. Although Aeromonas extraintestinal and systemic infections have been reported with growing frequency in recent years, Aeromonas septicaemia remains an uncommon finding, often associated with serious underlying disease and predominantly related to the species Aeromonas hydrophila, Aeromonas veronii biovar sobria and Aeromonas caviae. Here, a case of A. veronii biovar veronii septicaemia and acute suppurative cholangitis is reported in a patient with chronic hepatitis B.

Molecular cloning, sequencing and characterization of omp48, the gene encoding for an antigenic outer membrane protein from Aeromonas veronii

AIMS

To clone, sequence and characterize the gene encoding the Omp48, a major outer membrane protein from Aeromonas veronii.

METHODS AND RESULTS

A genomic library of Aer. veronii was constructed and screened to detect omp48 gene sequences, but no positive clones were identified, even under low stringency conditions. The cloned gene probably was toxic to the host Escherichia coli strain, so the cloning of omp48 was achieved by inverse PCR. The nucleotide sequence of omp48 consisted of an open reading frame of 1278 base pairs. The predicted primary protein is composed of 426 amino acids, with a 25-amino-acid signal peptide and common Ala-X-Ala cleavage site. The mature protein is composed of 401 amino acids with a molecular mass of 44,256 Da.

CONCLUSIONS

The omp48 gene from Aer. veronii was cloned, sequenced and characterized in detail. BLAST analysis of Omp48 protein showed sequence similarity (over 50%) to the LamB porin family from other pathogenic Gram-negative bacteria.

SIGNIFICANCE AND IMPACT OF THE STUDY

Bacterial diseases are a major economic problem for the fish farming industry. Outer membrane proteins are potentially important vaccine components. The characterization of omp48 gene will allow further investigation of the potential of Omp48 as recombinant or DNA vaccine component to prevent Aer. veronii and related species infections in reared fish.

Polyclonal bacteremia due to gram-negative rods

The frequency of, risk factors for, and outcome of polyclonal gram-negative bacteremia are still unknown. We investigated them in a prospective cohort study of patients for whom a blood culture yielded >/=1 species of gram-negative aerobic rod. For each patient, pulsed field gel electrophoresis (PFGE) was performed on 4 colonies of each morphologic type. Episodes of bacteremia were considered polyclonal if caused by >1 PFGE type of the same species. Ten (6.5%) of 153 investigated patients had polyclonal bacteremia. Bacteremia due to nonfermenting rods was the single significant risk factor for polyclonal bacteremia. Complications were equally frequent in all patient groups. However, patients with polyclonal bacteremia received more extensive antibiotic therapy than did patients with monoclonal bacteremia. Nearly 20% of episodes of bacteremia due to nonfermenting rods were polyclonal, but it remains unclear why nonfermenting rods were more likely to cause polyclonal bacteremia than were other gram-negative rods.

Production and secretion of collagen-binding proteins from Aeromonas veronii

Collagen-binding protein (CNBP) synthesized by Aeromonas veronii is located conserved within the subcellular fraction. The results of this study show that 98% of the total CNBP produced by Aer. veronii is present in the extracellular medium, and that the remaining CNBP is distributed either on the cell surface, within the periplasm or anchored on the outer membrane. CNBP is specifically secreted from Aer. veronii into the culture medium, because all the beta-lactamase activity was located in the cells and could be released by polymixin B extraction of periplasmic proteins. CNBP was produced at growth temperatures from 12 degrees C to 42 degrees C, but not at 4 degrees C. The findings indicate that the level of CNBP in the medium increases during the exponential growth phase and reaches a maximum during the early stationary phase. There was less CNBP production in poor nutrient MMB medium than in the rich LB nutrient medium. CNBP secretion, in contrast to aerolysin secretion, was unaffected by the exeA mutation of Aer. hydrophila. It is concluded that CNBP secretion from Aer. veronii must be achieved by a mechanism different from that reported for aerolysin secretion.

Spontaneous bacterial empyema caused by Aeromonas veronii biotype sobria

Spontaneous bacterial empyema is a complication of hepatic hydrothorax in cirrhotic patients. The pathogen, clinical course and treatment strategy are different to the empyema secondary to pneumonia. A 54-year-old man, who was a cirrhotic patient with hepatic hydrothorax, was admitted to National Taiwan University Hospital for fever, dyspnea and right side pleuritic pain. The image study revealed massive right pleural effusion and no evidence of pneumonia. The culture of pleural effusion yielded Aeromonas veronii biotype sobria. The diagnosis of spontaneous bacterial empyema caused by Aeromonas veronii biotype sobria was established. To our best knowledge, Aeromonas veronii biotype sobria had never been reported in English literature as the causative pathogen of spontaneous bacterial empyema.

Recurrent infections and chronic colonization by an Escherichia coli clone in the respiratory tract of a patient with severe cystic bronchiectasis

A 39-year-old woman with cystic bronchiectasis had repeated pulmonary infections from 1996 to 1999, and 6 of a total of 28 isolates of Escherichia coli from sputum specimens were studied. Their identical antibiotype and randomly amplified polymorphic DNA patterns indicated a single clone of E. coli, which persistently colonized the respiratory tract, causing recurrent infections.

The microbiology of necrotizing soft tissue infections

OBJECTIVE

A large number of necrotizing soft tissue infections (NSTI) treated at a single institution over an 8-year period were analyzed with respect to microbial pathogens recovered, treatment administered, and outcome. Based on this analysis, optimal empiric antibiotic coverage is proposed.

METHODS

A retrospective chart review of all patients with documented NSTI was conducted. Microbiologic variables were tested for impact on outcome using Fisher's exact test and multivariate analysis by logistic regression.

RESULTS

Review of the charts of 198 patients with documented NSTI revealed 182 patients with sufficient microbiologic information for analysis. These 182 patients grew an average of 4.4 microbes from original wound cultures, although a single pathogen was responsible in 28 patients. Eighty-five patients had combined aerobic and anaerobic growth, the most common organisms being, in order, Bacteroides species, aerobic streptococci, staphylococci, enterococci, Escherichia coli, and other gram-negative rods. Clostridial growth was common but did not affect mortality unless associated with pure clostridial myonecrosis. Mortality was affected by the presence of bacteremia, delayed or inadequate surgery, and degree of organ system dysfunction on admission.

CONCLUSIONS

NSTI are frequently polymicrobial and initial antibiotic coverage with a broad-spectrum regimen is warranted. The initial regimen should include agents effective against aerobic gram-positive cocci, gram-negative rods, and a variety of anaerobes. The most common organisms not covered by initial therapy were enterococci. All wounds should be cultured at initial debridement, as changes in antibiotic coverage are frequent once isolates are recovered.

Emergence of vancomycin-resistant enterococci at a university hospital in Taiwan: persistence of multiple species and multiple clones

OBJECTIVES

To describe the epidemiology of vancomycin-resistant enterococci (VRE) in a university hospital in Taipei, Taiwan.

DESIGN

Retrospective review over a 27-month period, from March 1996 to May 1998.

SETTING

A tertiary-care teaching hospital in Taiwan.

PARTICIPANTS

Patients with VRE isolated from any body site.

METHODS

Patients were identified through hospital microbiology and infection control records. Patient charts were reviewed for clinical and epidemiology data, including age, gender, previous hospital admissions, underlying diseases, types of infection, and recent antibiotic use. VRE isolates were characterized by their typical biochemical reactions, cellular fatty acid profiles, and the presence of van genes. Antibiotypes using the E-test and randomly amplified polymorphic DNA (RAPD) patterns of these isolates were used to determine the clonality.

RESULTS

Twenty-five isolates of VRE recovered from 12 patients were identified. One patient with a perianal abscess had 12 isolates of VRE (4 Enterococcus faecalis, 7 Enterococcus faecium, and 1 Enterococcus casseliflavus) recovered from perianal lesions. Among 3 patients who were hospitalized in the same room, 1 had a community-acquired cellulitis over the left leg caused by E. faecalis, and the other 2 patients both had anal colonization with 2 isolates of E. faecalis. The other 8 patients had 1 E. faecalis isolate each from various clinical specimens. All isolates possessed vanA resistance phenotype and vanA genes. Different antibiotypes and RAPD patterns of the isolates from different patients excluded the possibility of nosocomial spread at the hospital.

CONCLUSIONS

Multiple species of VRE (E. faecalis, E. faecium, and E. casseliflavus) and multiple clones of E. faecium could colonize or infect hospitalized patients. In addition, clones of VRE can persist long-term in patients' lower gastrointestinal tracts. These results extend our knowledge of the coexistence and the persistence of multiple species and multiple clones of VRE in hospitalized patients.