Clinical and laboratory characteristics of Achromobacter xylosoxidans infection

Urinary tract infection due toAchromobacter xylosoxidans: Report of 9 cases

Urinary tract infection (UTI) due to Achromobacter xylosoxidans is rare. The aims were to know the frequency and clinical characteristics of this infection in our area. We performed a retrospective analysis of 9 patients with UTI caused by this organism diagnosed over a period of 13 y. The mean age was 63.1 y. All patients had underlying diseases or urological abnormalities. The most frequent underlying diseases were solid or hematological malignancies (3 cases). Seven patients (77.7%) had urological abnormalities. Eight patients had symptoms of cystitis and 1 remained asymptomatic. Seven patients had community acquired UTIs. Clinical outcome was favourable in 5 patients after antibiotic treatment and recurrence occurred in 3 patients who had urological abnormalities. All isolates were susceptible to imipenem and piperacillin-tazobactam, 88.8% were susceptible to ceftazidime and 77.7% were susceptible to trimethoprim-sulfamethoxazole. High frequencies of resistance to ampicillin (100%), amoxicillin/clavulanic acid (78%), cefuroxime (100%), cefotaxime (67%), norfloxacin (89%), ciprofloxacin (78%), nitrofurantoin (89%) and gentamicin (67%) were observed. UTI due to A. xylosoxidans was predominantly observed in elderly patients with predisposing factors, especially urological abnormalities, malignancies and immunosuppression. Treatment can be difficult due to the high level of antibiotic resistance. Trimethoprim-sulfamethoxazole may be useful for treatment, particularly in outpatients with community acquired infections.

Diversity of bacteria that nodulate Prosopis juliflora in the eastern area of Morocco

A total of 274 bacterial strains were isolated from the root nodules of Prosopis juliflora, growing in two arid soils of the eastern area of Morocco. A physiological plate screening allowed the selection of 15 strains that could tolerate NaCl concentrations between 175 and 500 mM. These were compared with 15 strains chosen from among the ones which did not tolerate high salinity. The diversity of strains was first assessed by rep-PCR amplification fingerprinting using BOXA1R and ERIC primers. An analysis of the PCR-amplified 16S rDNA gene digestion profiles using five endonucleases indicated the presence of different lineages among the taxa associated with P. juliflora nodules in the soils studied. Nucleotide sequencing of the small subunit rRNA gene and BLAST analysis showed that P. juliflora could host at least six bacterial species in this region and that the identity of those associated with high salt tolerance was clearly distinct from that of the salt-sensitive ones. Among the former, the first type displayed 99% similarity with different members of the genus Sinorhizobium, the second 97% similarity with species within the genus Rhizobium, while the third ribosomal type had 100% homology to Achromobacter xylosoxidans. Within the salt-sensitive isolates the prevailing type observed showed 98% similarity with Rhizobium multihospitium and R. tropici, a second type had 98% similarity to R. giardinii, and a further case displayed 97% colinearity with the Ensifer group including E. maghrebium and E. xericitae. All of the thirty strains encompassing these types re-nodulated P. juliflora in microbiologically controlled conditions and all of them were shown to possess a copy of the nodC gene. This is the first report detecting the betaproteobacterial genus Achromobacter as nodule-forming species for legumes. The observed variability in symbiont species and the abundance of nodulation-proficient strains is in line with the observation that the plant always appears to be nodulated and efficiently fixing nitrogen in spite of a wide range of soil and environmental conditions.

Inherent antibacterial activity of a peptide-based beta-hairpin hydrogel

Among several important considerations for implantation of a biomaterial, a main concern is the introduction of infection. We have designed a hydrogel scaffold from the self-assembling peptide, MAX1, for tissue regeneration applications whose surface exhibits inherent antibacterial activity. In experiments where MAX1 gels are challenged with bacterial solutions ranging in concentrations from 2 x 10(3) colony forming units (CFUs)/dm2 to 2 x 10(9) CFUs/dm2, gel surfaces exhibit broad-spectrum antibacterial activity. Results show that the hydrogel surface is active against Gram-positive (Staphylococcus epidermidis, Staphylococcus aureus, and Streptococcus pyogenes) and Gram-negative (Klebsiella pneumoniae and Escherichia coli) bacteria, all prevalent in hospital settings. Live-dead assays employing laser scanning confocal microscopy show that bacteria are killed when they engage the surface. In addition, the surface of MAX1 hydrogels was shown to cause inner and outer membrane disruption in experiments that monitor the release of beta-galactosidase from the cytoplasm of lactose permease-deficient E. coli ML-35. These data suggest a mechanism of antibacterial action that involves membrane disruption that leads to cell death upon cellular contact with the gel surface. Although the hydrogel surface exhibits bactericidal activity, co-culture experiments indicate hydrogel surfaces show selective toxicity to bacterial versus mammalian cells. Additionally, gel surfaces are nonhemolytic toward human erythrocytes, which maintain healthy morphologies when in contact with the surface. These material attributes make MAX1 gels attractive candidates for use in tissue regeneration, even in nonsterile environments.

A novel bacterium Achromobacter xylosoxidans as a cause of liver abscess: three case reports

Achromobacter xylosoxidans is a microorganism that may cause opportunistic infections. We detected A. xylosoxidans in three of 46 patients with liver abscess. The clinicopathologic findings of the three patients were uniform with respect to a prior history of cholecystectomy, multi-lobulated 'coral-like' abscess under CT and epithelioid granulomas in the periphery of the abscess. Achromobacter xylosoxidans is an unrecognized cause of liver abscess in humans.

Bacteremia caused by Achromobacter and Alcaligenes species in 46 patients with cancer (1989-2003)

BACKGROUND

Achromobacter and Alcaligenes are emerging infectious gram-negative bacterial species that can affect immunosuppressed patients. The authors sought to determine the incidence and characteristics of bloodstream infections caused by these organisms in patients with underlying malignancies.

METHODS

All consecutive episodes of hematogenous Achromobacter and Alcaligenes infections recorded from December 26, 1989, to July 27, 2003, were studied retrospectively.

RESULTS

Fifty-two episodes occurred in 46 patients; 31 patients (67%) had hematologic malignancies, and 24 (52%) experienced neutropenia (< 500 cells/microL). Diabetes mellitus was present in 12 patients (26%), and high-dose corticosteroids were administered to 12 patients (26%). Seventeen of the 52 infectious episodes (33%) were nosocomial in origin, and 10 patients (22%) had sepsis syndrome. Achromobacter xylosoxidans was the most common cause of infection (47 of 52 episodes [94%]), followed by Ach. denitrificans (2 of 52 episodes [4%]) and Alcaligenes faecalis (1 of 52 episodes [2%]). Twenty-seven episodes (52%) were polymicrobial, and 3 patients (7%) had concurrent fungemia. Infected intravascular catheters were present in 13 of 52 cases (25%), pneumonia was encountered in 6 of 52 cases (12%), and urinary tract infections were present in 5 of 52 cases (10%). Most isolates exhibited in vitro susceptibility to carbapenems, antipseudomonal penicillins, and trimethoprim-sulfamethoxazole. Resistance to ciprofloxacin, levofloxacin, aminoglycosides, and monobactam was common. Seven deaths (15%) were attributable to Achromobacter species. Incidence rates for sepsis syndrome, multiorgan dysfunction (Acute Physiology and Chronic Health Evaluation [APACHE] II score > 16), and use of mechanical ventilation and pressor support were significantly higher in patients who died (P < 0.001). Logistic regression analysis revealed that sepsis syndrome and high APACHE II scores were predictors of increased 30-day mortality.

CONCLUSIONS

Most infections caused by this group of nonfermentative gram-negative bacteria were attributable to Ach. xylosoxidans, and only one-third were acquired during hospitalization. The presence of sepsis syndrome has evolved as an independent predictor of poor outcome in patients with high-risk malignancies accompanied by Achromobacter bloodstream infections.

Epidemiological typing of Alcaligenes xylosoxidans subsp. xylosoxidans by antibacterial susceptibility testing, fatty acid analysis, PAGE of whole-cell protein and pulsed-field gel electrophoresis

Antibacterial susceptibility testing, fatty acid analysis, protein analysis and DNA analysis of Alcaligenes xylosoxidans subsp. xylosoxidans were compared to determine the efficiency of the methods available for strain typing. Thirty isolates were investigated: 20 clinical isolates from a nonsocomial outbreak in Essen (Germany), 9 clinical isolates from sporadic nosocomial cases in Paris (France) and reference strain ATCC 2402. The highest microbiological discriminative power was exhibited by pulsed-field gel electrophoresis (PFGE) yielding nine types, followed by fatty acid methyl ester (FAME) analysis with six types, and antibacterial susceptibility testing and polyacrylamide gel electrophoresis with five types each. By combining the results of the four typing methods, 14 varieties could be differentiated. Protein analysis and fatty acid analysis failed to discriminate between isolates from Essen and Paris and the reference strain, while antibacterial susceptibility testing and DNA analysis clearly discriminated them. It is concluded that a combination of antibacterial susceptibility testing and PFGE typing is most suitable for epidemiological typing of Alcaligenes xylosoxidans subsp. xylosoxidans strains.

Alcaligenes Xylosoxidans Subsp Xylosoxidans in Children with Chronic Otorrhea

Because other known pathogens are frequently isolated with AXX, its clinical significance may be overlooked. AXX should not be considered a colonizer or contaminant, particularly in the presence of clinical signs and symptoms of infection. For a pediatric patient with AXX in the ear fluid, the choice of an antibiotic regimen should be based on in vitro activity of both AXX and other concurrent pathogens. Although the sensitivity of AXX may be highly variable, a number of antibiotics appear to be clinically useful.

Bacteremia and urinary tract infection associated with CDC group Vd biovar 2

A case of urinary tract infection and bacteremia caused by CDC group Vd biovar 2 in a 23-year-old woman with Hodgkin's disease is described. This is the first report of CDC group Vd biovar 2 isolated from a clinical specimen and considered as a pathogen. Detailed antimicrobial susceptibility data are presented.

Nosocomial outbreak of Achromobacter xylosoxidans associated with a diagnostic contrast solution

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Achromobacter xylosoxidans (Alcaligenes xylosoxidans subsp. xylosoxidans) bacteremia associated with a well-water source: case report and review of the literature

A case of community-acquired Achromobacter xylosoxidans bacteremia in a patient with metastatic breast carcinoma is described. The patient's home drinking water was identified as the source of her bacteremia. The case represents the first in which a community-acquired infection due to this organism has been attributed to a documented water source.

In vitro susceptibility of Alcaligenes denitrificans subsp. xylosoxidans to 24 antimicrobial agents

The in vitro susceptibilities of 37 clinical isolates of Alcaligenes denitrificans subsp. xylosoxidans to 24 antimicrobial agents were determined. Imipenem was the only drug with consistent activity (MIC for 90% of isolates, 2 micrograms/ml). Piperacillin, ticarcillin-clavulanic acid, ceftazidime, and co-trimoxazole were active against most strains. All the isolates were resistant to ampicillin, cefazolin, cefuroxime, cefamandole, cefotetan, ceftriaxone, cefotaxime, aztreonam, amdinocillin, and temocillin. Most isolates were resistant to the aminoglycosides tested, including amikacin. Lack of activity was also observed for all new 4-quinolone antimicrobial agents.

Nosocomial Achromobacter xylosoxidans infections

A xylosoxidans is being recognized as an important nosocomial pathogen. As more patients are rendered immunosuppressed by chemotherapy, this organism's increasing role in hospital-acquired infections will be assured. Achromobacter is a water-borne organism, highly resistant to most antibiotics, and even to some disinfectant solutions, and easily establishes itself in the hospital aquatic environment. Achromobacter infections and outbreaks should be recognized and approached as serious problems requiring the institution of appropriate infection control measures. A xylosoxidans infections should be empirically treated with a combination of a third generation cephalosporin and TMP-SMX pending susceptibility testing.

Diversity of plasmids in Achromobacter xylosoxidans isolates responsible for a seemingly common-source nosocomial outbreak

Achromobacter xylosoxidans, an uncommon yet highly resistant opportunistic pathogen, was isolated from nine hospitalized patients during an 8-month period. It had been isolated from only seven patients with either nonfatal infection or colonization from 1981 to 1984. From June 1985 to January 1986, A. xylosoxidans was isolated 18 times from seven different sites (sputum, 7 times; urine, 4 times; blood, 3 times; and lung, pleural fluid, wound tissue, and tracheal aspirate, 1 time each). Four patients died, including the three with bacteremia. All but two patients had nosocomial infections and either were on the same ward or were cared for by the same staff members. Eleven A. xylosoxidans strains yielded eight distinct plasmids (8, 21, 23, 26, 38, 50, 51, and 64 megadaltons). Whole-cell peptide patterns of 10 of these strains were determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Isolates from the same patient contained the same plasmids and had identical peptide patterns but differed from other strains in both parameters. Plasmids were absent from the two community-acquired isolates. Although nosocomial strains showed similar antibiotic resistance patterns (only moxalactam and ticarcillin-clavulanic acid were uniformly active) and cross-contamination was strongly suggested epidemiologically, results of plasmid and peptide analyses did not support the possibility of a single-strain outbreak.

Puncture wound osteochondritis of the foot caused by CDC group Vd

A case of puncture wound osteochondritis of the foot caused by CDC group Vd is presented because of the unusual nature of the infecting organism. This organism may be confused with Pseudomonas aeruginosa, the usual pathogen responsible for this type of infection, but does not have a similar antimicrobial susceptibility profile. For this reason, it is important to obtain appropriate culture specimens and to identify and test the susceptibility of bacterial isolates from cases of puncture wound-associated osteochondritis so that optimal therapeutic regimens can be determined.

Peritonitis caused by Alcaligenes denitrificans subsp. xylosoxydans: case report and review of the literature

We report the third human case of peritonitis caused by Alcaligenes denitrificans subsp. xylosoxydans and review the English literature regarding community-acquired and nonsocomial infection and colonization that results from this bacterium. The biochemical and genetic characteristics supporting the pathogenic potential of A. denitrificans subsp. xylosoxydans are reviewed, and the antimicrobial susceptibility profile of the organism is summarized.

Infections due to Achromobacter xylosoxidans. Case report and review of the literature

Achromobacter xylosoxidans is an uncommon nosocomial pathogen known to cause many serious infections. A 69-year-old woman with diabetes mellitus and chronic renal failure was admitted with pulmonary edema. The patient developed fever and pulmonary infiltrate with bilateral pleural effusions while she was on a respirator in the intensive care unit. Culture of sputum, pleural fluid and blood grew A. xylosoxidans. Bilateral chest tubes were inserted and the patient was treated for one month with piperacillin and trimethoprim-sulfamethoxazole. Gradual response, both clinically and radiologically, was noted after prolonged therapy. A review of the literature on infections due to A. xylosoxidans, the unique susceptibility pattern of the organism to various antibiotics and the use of combination therapy in Achromobacter infections are discussed.

Corneal ulcer due to Achromobacter xylosoxidans

We report a case of corneal ulcer caused by the opportunistic organism Achromobacter xylosoxidans which developed during chronic topical steroid treatment of an eye with neovascular glaucoma. A. xylosoxidans has probably been underreported as a cause of ocular infection because of confusion between this organism and other Gram-negative organisms, particularly pseudomonas. A. xylosoxidans is resistant to aminoglycosides and some cephalosporins but not carbenicillin. This difference in antibiotic sensitivity patterns between A. xylosoxidans and pseudomonas makes an accurate differentiation between the 2 organisms important. This case was successfully treated after substituting topical carbenicillin for topical gentamicin and amikacin.

Bacteremia caused by Achromobacter species in an immunocompromised host

A case of bacteremia caused by Achromobacter species in an immunocompromised patient is described. The patient responded to antibiotic therapy. Detailed antibiotic susceptibility data are presented.

Nosocomial colonization and infection by Achromobacter xylosoxidans

Achromobacter xylosoxidans, a bacterial species named in 1971, is often isolated from aqueous environments, but little has been reported about its pathogenicity in humans, its epidemiological pattern, and its susceptibility to antibiotics and antiseptics. We were faced with an epidemic caused by this microorganism for 18 months in an intensive care unit. Two patients had fatal infections and 37 others were colonized. The source was the deionized water of the hemodialysis system. The 46 isolates were identified by comparison with the reference strain A. xylosoxidans ATCC 27061. The characteristic cellular fatty acids of this species were demonstrated by gas-liquid chromatography. The minimal inhibitory concentrations of 27 antibiotics were determined. The isolates were susceptible to only two: moxalactam at 4 micrograms/ml and ceftazidime at 8 micrograms/ml. The minimal bactericidal concentrations of one disinfectant and three antiseptics were: sodium hypochloride, 109 micrograms/ml; chlorhexidine digluconate in ethanol solution, 15 to 125 micrograms/ml; polyvinylpyrrolidone iodine, 750 micrograms/ml; and iodine ethanol, 312 to 625 micrograms/ml.