B. Gordts

Third Belgian multicentre survey of antibiotic susceptibility of anaerobic bacteria.

OBJECTIVES To collect recent data on the susceptibility of anaerobes and to compare them with results from previous studies. METHODS Four hundred and forty-three anaerobic clinical isolates from various body sites were prospectively collected from October 2003 to February 2005 in nine Belgian hospitals. MICs were determined for nine anti-anaerobic and three recently developed antibiotics. RESULTS Most gram-negative bacilli except Fusobacterium spp. were resistant to penicillin. Piperacillin/tazobactam, metronidazole, chloramphenicol, meropenem and amoxicillin/clavulanic acid were very active against all groups, but only 86% of Bacteroides fragilis group strains were susceptible to the latter. Cefoxitin, cefotetan and clindamycin were less active. In particular, only 62%, 52% and 48% of B. fragilis group strains were susceptible, respectively. Clindamycin shows a continuing decrease in activity, as 83% were still susceptible in 1987 and 66% in 1993-94. Anti-anaerobic activity of the new antibiotics is interesting, with MIC50 and MIC90 of 1 and >32 mg/L for moxifloxacin, 2 and 4 mg/L for linezolid and 0.5 and 8 mg/L for tigecycline. CONCLUSIONS The susceptibility of anaerobic bacteria remains stable in Belgium, except for clindamycin, which shows a continuous decrease in activity. However, for each of the tested antibiotics, at least a few resistant organisms were detected. Consequently, for severe infections involving anaerobic bacteria, it could be advisable to perform microbiological testing instead of relying on known susceptibility profiles. Periodically monitoring background susceptibility remains necessary to guide empirical therapy.

Methicillin-resistant Staphylococcus aureus ST398 in swine farm personnel, Belgium

We assessed methicillin-resistant Staphylococcus aureus (MRSA) in persons on 49 swine farms in Belgium. Surveys showed that 48 (37.8%) persons carried MRSA ST398 and 1 (0.8%) had concurrent skin infection. Risk factors for carriage were MRSA carriage by pigs, regular contact with pigs and companion animals, and use of protective clothing.

Differentiation and identification of Enterococcus durans, E. hirae and E. villorum

Aims: To compare different tests in the identification of Enterococcus durans, E. hirae and E. villorum strains. These bacteria belong to the E. faecium species group and are phylogenetically closely related, as evidenced by 16S rRNA sequence homologies of over 98·8%.

Prevalence and Antimicrobial Susceptibility of Methicillin-Resistant Staphylococcus aureus Among Pigs in Belgium

The prevalence, distribution, and antimicrobial susceptibility of methicillin-resistant Staphylococcus aureus (MRSA) in Belgian pig farms has been investigated. To that end, nasal samples were collected from 1,500 pigs on 50 farms randomly selected over Belgium. Both closed (breeding or farrow-to-finish) and open (fattening) farms were included. Within closed farms different age groups were investigated. A total number of 663 (44%) pigs belonging to 34 (68%) farms carried MRSA. According to their management practice, MRSA was detected on 94% of the open farms and 56% of the closed farms. Focusing on the in-herd prevalence among fattening pigs for both management systems, a significantly higher rate was found in open farms (72%) compared to closed farms (26%). Within the closed farms, piglets (41%) showed a higher MRSA prevalence than sows (26%) and fattening pigs (26%). All strains tested were ST398 and showed mainly spa-type t011, as commonly found on pig herds in Europe. Less dominating spa-types were t034, t567, and t2970. The MRSA strains carried two SCCmec-types, type IVa or V. All 643 MRSA strains were resistant to tetracycline and additional resistances to trimethoprim (97%), lincosamides (73%), macrolides (56%), aminoglycosides (48%), and fluoroquinolones (32%) were found. Multiresistance (defined as resistance to four or more non-β-lactam antimicrobial classes) was found in 63% of the tested strains. In conclusion, a high prevalence of MRSA was found in Belgian pig farms, with the highest prevalence in open farms. In accordance with other European countries, age-related and management-related differences in MRSA prevalence were observed that should be considered when control strategies are outlined.

Susceptibility of clinical isolates of Fusarium to antifungal drugs

Summary. The inhibitory activities of amphotericin B, fluconazole, itraconazole, miconazole, ketoconazole and terbinafine against nine isolates from clinically apparent infections of Fusarium solani, four isolates of Fusarium moniliforme and 10 isolates of Fusarium oxysporum were determined with an agar diffusion method (Neo‐sensitabs) and an agar dilution method. The inhibition zones obtained with antifungal Neo‐sensitabs need very careful interpretation. We did not find a good correlation between the agar diffusion method using Neo‐sensitabs preloaded with azoles and amphotericin B and the agar dilution method. Amphotericin B (12/23) and terbinafine (18/23) showed good activity. Miconazole (7/23) and ketoconazole (3/23) had poor inhibitory activity. Fluconazole and itraconazole (0/23) had no in vitro activity against any of the isolates tested.

Surveillance of aminoglycoside resistance: European data☆

The susceptibility patterns of gram-negative aerobic organisms to aminoglycosides differ widely from one European health care center to another and depend upon local antibiotic prescribing policies. Reports of the susceptibility of Pseudomonas aeruginosa to gentamicin and tobramycin have ranged from as low as 49.8 percent and 77.7 percent, respectively, in Greece, to as high as 96.6 percent and 99.2 percent, respectively, in the United Kingdom. The susceptibility of P. aeruginosa to gentamicin, tobramycin, and amikacin decreased in our hospital from 73.1 percent, 94.8 percent, and 95.6 percent, respectively, in 1982, to 43.1 percent, 70.6 percent, and 74.3 percent, respectively, in 1984. A prospective surveillance study of the susceptibility of gram-negative aerobic bacilli to four aminoglycosides (gentamicin, tobramycin, amikacin, and netilmicin) was performed over a period of 17 months. Gentamicin and tobramycin were freely used, while the use of amikacin was restricted throughout the hospital during a four-month baseline period (May through August 1984). Gentamicin and tobramycin accounted for 94 percent of the aminoglycoside use. During the following 13 months (September 1984 through September 1985), amikacin was used as the first-line aminoglycoside and accounted for more than 97 percent of the aminoglycoside usage. A total of 1,866 organisms were analyzed during the baseline period; 5,429 were analyzed during the amikacin-usage period. The overall susceptibility to gentamicin, tobramycin, amikacin, and netilmicin increased from 86.9 percent, 90.4 percent, 94.2 percent, and 88.3 percent, respectively, to 92.3 percent, 94.0 percent, 97.3 percent, and 92.3 percent, respectively. P. aeruginosa isolates had the most striking changes, with the susceptibility to gentamicin, tobramycin, amikacin, and netilmicin increasing from 43.1 percent, 70.6 percent, 74.3 percent, and 50.6 percent, respectively, during the baseline period, to 64.5 percent, 81.6 percent, 90.8 percent, and 65.1 percent, respectively, during the amikacin-usage period. The use of amikacin as a first-line aminoglycoside, while use of the other aminoglycosides was restricted, seemed to have a favorable influence on the susceptibility pattern of gram-negative aerobic isolates in our hospital.

Dual infection with polyomavirus BK and acyclovir-resistant herpes simplex virus successfully treated with cidofovir in a bone marrow transplant recipient

Abstract: A hematopoietic stem cell transplant recipient developed a mucosal herpes simplex virus‐1 (HSV‐1) infection while under acyclovir (ACV) treatment (HSV was later shown to be resistant to ACV). Concomitantly, the patient presented a hemorrhagic cystitis (HC) due to polyomavirus BK, for which intravenous cidofovir (CDV) was prescribed. The patient benefited from the broad‐spectrum anti‐DNA virus activity of CDV, and not only the HC resolved without signs of nephrotoxicity but also the HSV‐1 lesions disappeared. This is the first report describing the effect of CDV on 2 simultaneous and unrelated DNA viral infections in an immunosuppressed transplant recipient. In addition, we describe here that this HSV‐1 isolate possesses a unique phenotype and genotype.

Fatal aeromonas hydrophila bacteremia in a hemodialysis patient treated with deferoxamine

A 49-year-old woman undergoing long-term hemodialysis and treated with deferoxamine (DFO) 1.5 g twice weekly for aluminum bone disease developed fever and bilateral calf pain caused by myonecrosis with gas gangrene. She had a rapidly fatal outcome. The cultures of blood and aspirates from both calf muscles demonstrated Aeromonas hydrophila. No obvious entry point could be traced. The in vitro growth of the patients strain was found to be stimulated by the deferoxamine-iron complex in an iron-deprived medium. It is suggested that high-dose DFO therapy in this patient was responsible for promoting a bacterial infection by this microorganism.

Effect of ferrioxamine on the growth of Rhizopus

Summary. Zygomycosis, caused by Rhizopus spp., has recently been reported to occur in dialysis patients treated with desferrioxamine, suggesting a role of this drug in the pathogenesis of this infection. The hypothesis that ferrioxamine, the iron chelate of desferrioxamine, stimulates the growth of Rhizopus spp. has been brought forward. The growth rate of 2 × 105 spores of R. rhizopodiformis (isolated from a dialysis patient who died of zygomycosis while on desferrioxamine therapy) was studied in an iron‐deficient medium (1) with human serum at increasing concentrations and (2) with 40% human serum in the presence of ferrioxamine at different concentrations. After grinding the mycelium, growth was measured by absorbance density at 450 nm. The results show that a concentration of 40% human serum inhibits the growth of R. rhizopodiformis >50% and that, in the presence of serum, ferrioxamine causes a significant growth stimulation at 24 h that persists at 48 h. In conclusion, ferrioxamine stimulates the growth of R. rhizopodiformis in vitro. This probably plays a key role in the pathogenesis of desferrioxamine‐related zygomycosis.

Prosthetic valve endocarditis due to Listeria monocytogenes. A case report with review of the literature.

We report the case of a 71-year-old man with a prosthetic aortic valve endocarditis caused by Listeria monocytogenes. He was successfully treated with a combination of ampicillin and amikacin, and valve replacement surgery. This case and previously reported cases are discussed.