Drug-resistant Streptococcus pneumoniae in the Lebanon: implications for presumptive therapy.

A total of 50 consecutive clinical isolates of Streptococcus pneumoniae, collected between 1996 and 1998, were tested against six antimicrobial agents using the E-test. The percentages of fully resistant (R) and intermediately-R strains, respectively, were: benzyl penicillin 18 and 38%, amoxycillin-clavulanate 6 and 12%, cefuroxime 22 and 16%, ceftriaxone 2 and 16%, and clarithromycin 10%. Fully and or intermediately multidrug-resistance (two or more drugs) was seen in 44% of the isolates, 18% being fully resistant. The MIC breakpoint for cefaclor is not defined by the National Committee for Clinical Laboratory Standards (NCCLS) but MICs showed that: 76% of the isolates had an MIC of ≤8 mg/l, 4% had an MIC of 16 mg/l and 20% had an MIC of ≥32 mg/l. There was agreement between the E-test Pen MIC results and the 1 μg oxacillin (oxa) disk diffusion screen test for the 22 susceptible and the nine fully R strains but not for the 19 strains with Pen MICs between 0.1 and 1 mg/l; this shows the importance of MIC determination in such isolates. Penicillin and multiply antibiotic-resistant pneumococci are spreading in Lebanon, emphasizing the necessity to reconsider current treatment regimens in this country.     

High incidence of antifungal drug resistance in Candida tropicalis

Drug resistance among yeasts is an increasing problem. Isolates of Candida krusei and Candida glabrata are recognized as having reduced susceptibility to fluconazole and resistance to this drug has also arisen in Candida albicans isolated from AIDS patients on long term azole therapy. Candida tropicalis (CT) is being increasingly isolated from human disease and is associated with invasive infection, however, data regarding this organism's drug susceptibility is limited. We report our findings on 60 isolates of CT isolated from patients with serious infection in the North West of England. Over 60% of isolates were from adult Intensive Care Unit (ICU) patients, and almost half were from the respiratory tract. Susceptibility to fluconazole, flucytosine, itraconazole and ketoconazole were tested by standardised methods - 48% of the isolates were resistant to fluconazole (MIC > 12.5 mg/l), and 10% had intermediate susceptibility (MIC 6.25–12.5 mg/l). For flucytosine 17% of isolates were resistant (MIC > 8 mg/l) and 22% had intermediate susceptibility (MIC 2–8 mg/l). Three isolates were resistant to both drugs. For itraconazole 17% of isolates were resistant (MIC > 1 mg/l), and 12% showed intermediate susceptibility (MIC 0.5–1 mg/l). Resistance to ketoconazole was seen in 33% of isolates (MIC > 1 mg/l) and 10% showed intermediate susceptibility (MIC 0.5–1 mg/l). Differences in the degree of cross resistance between the azole drugs was observed. Candida tropicalis should be added to the list of yeasts in which drug resistance is commonly found. Given the high invasiveness of Candida tropicalis, its affinity for patients on ICU and the high incidence of drug resistance in this species, identification and susceptibility tests should be performed on all yeast isolates from patients on ICU.     

Comparative activity of ceftizoxime against aminoglycoside-resistant aerobic gram-negative bacilli

The in vitro activity of ceftizoxime was compared with that of other beta-lactam antibiotics against 331 aminoglycoside (AG)-resistant clinical isolates. Two hundred and six AG-resistant, beta-lactamase producing, R-plasmid harbouring Enterobacteriaceae strains had MICs ranging from 0.0125 to 0.063 mg/l. AG-resistant Escherichia coli (36 strains) and Klebsiella pneumoniae (19) had MIC 90 values of 8 mg/l. Proteus rettgeri and P. vulgaris as well as Morganella morganii, resistant to several AGs, had MICs ranging from 0.5 to 4 mg/ml. Against all six isolates of AG-resistant Salmonella enteritidis the MIC90 was 0.5 mg/l. Twenty-seven strains of Serratia marcescens, most of which were resistant to beta-lactam and AG antibiotics, had MICs ranging from 0.5 to 8 mg/l. The AG-resistant strains of Enterobacteriaceae producing several AG-modifying enzymes (AAC(3); AAC(2'); AAC(6'); APH(3')) showed MICs ranging from 0.6 to 4 mg/l. Against 10 AG-resistant strains of Pseudomonas aeruginosa producing AAC(3), AAC(6') and APH(3') enzymes, the MICs ranged from 16 to 64 mg/l. In conclusion, ceftizoxime was equally or more active than cefotaxime, cefoperazone, ceftazidime and moxalactam against AG-resistant E. coli, Klebsiella, Morganella, Proteus, Serratia, Salmonella and R-plasmid harbouring Enterobacteriaceae. Ceftizoxime was less active than cefotaxime, moxalactam and ceftazidime against P. aeruginosa.     

In vitro activity of ABT-773, telithromycin and eight other antimicrobials against erythromycin-resistant Streptococcus pneumoniae respiratory isolates of children

The activity of the ketolide ABT-773 against 180 erythromycin-resistant Streptococcus pneumoniae obtained from children was compared with telithromycin, azithromycin, clarithromyin, roxithromycin, clindamycin, penicillin, levofloxacin and gatifloxacin. Ketolide MICs were all ≤1 mg/l, with ABT-773 being the most potent of all drugs tested. MIC₉₀s for macrolides and azithromycin in mefE+ isolates were 16–32 compared with >128 mg/l for ermB+ isolates. ABT-773 and telithromycin MIC₉₀s for mefE+ isolates were 0.125 and 0.5, compared with 0.032 and 0.016 mg/l for ermB+ isolates and 0.5 and 1 mg/l, respectively, for isolates containing both genes. Clindamycin was active against mefE+ but not ermB+ isolates. 155 isolates were resistant to penicillin. All fluoroquinolone MICs were <1 mg/l. Further studies of ketolides for treatment of paediatric S. pneumoniae infections are warranted.     

Investigation of the prevalence of tetQ, tetX and tetX1 genes in Bacteroides strains with elevated tigecycline minimum inhibitory concentrations

In this study, the antibiotic susceptibilities to tigecycline and tetracycline of 35 selected Bacteroides fragilis group strains were determined by Etest, and the presence of tetQ, tetX, tetX1 and ermF genes was investigated by polymerase chain reaction (PCR). tetQ was detected in all 12 B. fragilis group isolates (100%) exhibiting elevated tigecycline minimum inhibitory concentrations (MICs) (≥8 μg/mL) as well as the 8 strains (100%) with a tigecycline MIC of 4 μg/mL, whilst tetX and tetX1 were present in 15% and 75% of these strains, respectively. All of these strains were fully resistant to tetracycline (MIC ≥ 16 μg/mL). On the other hand, amongst the group of strains with tigecycline MICs < 4 μg/mL (15 isolates), tetQ, tetX and tetX1 were found less frequently (73.3%, 13.3% and 46.7%, respectively). All but two strains harbouring the tetQ gene in this group were non-susceptible to tetracycline, with a MIC > 4 μg/mL. These data suggest that in most cases tigecycline overcomes the tetracycline resistance mechanisms frequently observed in Bacteroides strains. However, the presence of tetX and tetX1 genes in some of the strains exhibiting elevated MICs for tigecycline draws attention to the possible development and spread of resistance to this antibiotic agent amongst Bacteroides strains. The common occurrence of ermF, tetX, tetX1 and tetQ genes together predicted the presence of the CTnDOT-like Bacteroides conjugative transposon in this collection of Bacteroides strains.     

Activity of moxifloxacin and other quinolones against pneumococci resistant to first-line agents, or with high-level ciprofloxacin resistance

The activity of moxifloxacin and other quinolones was assessed against 288 epidemiologically diverse isolates of Streptococcus pneumoniae, many of them resistant to one or more first-line agents and/or with increased ciprofloxacin resistance (minimum inhibitory concentrations, MICs 16- > 64 mg/l compared with 1-2 mg/l for most isolates). Moxifloxacin and grepafloxacin were the most active quinolone analogues, inhibiting about 90% of the isolates at < or = 1 mg/l, whereas levofloxacin inhibited 64% of isolates at < = 1 mg/l and ciprofloxacin inhibited 42%. Moxifloxacin also was the most active agent against isolates with elevated ciprofloxacin resistance (MIC 16- > 64 mg/l): moxifloxacin MICs of around 4 mg/l were seen for most such isolates, compared with 16-32 mg for levofloxacin and grepafloxacin. The activity of moxifloxacin against pneumococci resistant to one or more first-line agent suggests it will have a useful therapeutic role, although its activity against highly ciprofloxacin resistant isolates seems marginal.     

In vitro activity of moxifloxacin against recent community-acquired respiratory tract pathogens isolated in France: a national survey

Between February and June 2000, 2345 consecutive strains of Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, Staphylococcus aureus and Klebsiella pneumoniae were isolated from 2088 adult patients suffering from community-acquired respiratory tract infections, in 97 hospital laboratories. Of the 1037 S. pneumoniae isolates, 48.3% were intermediately or highly penicillin resistant. For invasive isolates, the MIC90s of penicillin G, amoxycillin, cefuroxime, ceftriaxone, erythromycin, ofloxacin, ciprofloxacin and moxifloxacin were 2, 2, 4, 0.5, 1024, 2, 2 and 0.25 mg/l, respectively. All but one invasive strain were susceptible to moxifloxacin whereas 97.5% were susceptible to levofloxacin. The MIC90s of clinical isolates with intermediate susceptibility or high resistance to penicillin G, were 2, 2, 4, 1, 1024, 2, 2 and 0.25 mg/l. About 98.1, 97.0, and 83.1% of strains were inhibited by concentrations < or = 1 mg/l of moxifloxacin, levofloxacin and ciprofloxacin, respectively (E-test). Eight of the 1037 S. pneumoniae strains were not susceptible to moxifloxacin and had mutations in gyrA (eight strains), parC (four strains) or parE (three strains). Against H. influenzae (32.7% were beta-lactamase producers) and M. catarrhalis (96.3% were beta-lactamase producers), the MIC90s of moxifloxacin, amoxycillin and co-amoxiclav were 0.094 and 0.125 mg/l, 64 and 8 mg/l, and 1.5 and 0.25 mg/l, respectively. Against oxacillin-susceptible S. aureus and K. pneumoniae, the MIC90s of moxifloxacin were 0.125 and 0.84 mg/l respectively. Moxifloxacin had the highest in vitro activity of all antibiotics tested.     

Antimicrobial susceptibility and serogroups of Salmonella isolates from Riyadh, Saudi Arabia

The antimicrobial susceptibility and serogroups of 153 Salmonella strains isolated during a period of 22 months from both children and adults at a major teaching hospital in Riyadh, Saudi Arabia were studied. Antimicrobial susceptibility testing by comparative disc method and MIC determination by E-test method were performed on selected antimicrobial agents. For nalidixic acid and trimethoprim only the comparative disc method was used. Discrepancy between the two methods were noticed only in 1.3% of isolates. The majority of isolates from children (41%) were serogroup B, while those from adults (43%) were serogroup C1. The overall resistance was 16% to ampicillin and ampicillin/sulbactam, 13% to nalidixic acid, and 11% to chloramphenicol and trimethoprim/sulphamethoxazole. The resistance of Salmonella isolates to the so-called first line anti-Salmonella agents, i.e. ampicillin, chloramphenicol and trimethoprim/sulphamethoxazole, has increased compared to that reported 4 years ago from this Institution. Almost all isolates were susceptible to the second, and third generation cephalosporins, fluoroquinolones, aztreonam, mecillinam and gentamicin. Multiple drug resistance to two or more drugs was noticed in 16% of isolates, most of which were serogroup B. The majority of these multiple drug resistant isolates (96%) were ampicillin resistant and β-lactamase producers. Although these isolates showed reduced MICs to ampicillin/sulbactam, their MICs were still higher than the susceptibility breakpoint for this combination. The nalidixic acid-resistant isolates showed higher MICs to the fluoroquinolones compared to the nalidixic acid-sensitive isolates. Isolates from children showed higher resistance to some of the antimicrobial agents compared to those from adults.     

In vitro activity of voriconazole against Candida species isolated in Taiwan

The activity of voriconazole was determined against 285 Candida species consisting of 53 resistant isolates, 43 susceptible-dose dependent and 189 isolates susceptible to fluconazole. The MIC(50) and MIC(90) to fluconazole were 8 and 64 mg/l, respectively. The range of minimum inhibitory concentrations (MICs) to voriconazole was from 0.0325 to 2 mg/l and the MIC(50) and MIC(90) were 0.125 and 0.5 mg/l, respectively. Only 3 of 285 tested isolates had MICs to voriconazole equal to 2 mg/l. A total of 38 isolates, consisted of 3 Candida albicans, 5 Candida krusei, 7 Candida tropicalis and 21 Candida glabrata, had >/= 0.5 mg/l to voriconazole. There was correlation between the susceptibility to fluconazole and voriconazole.     

In vitro activity of oral cephalosporin BAY v 3522 compared with other oral cephalosporins

Minimal inhibitory concentrations (MICs) of the oral cephalosporin BAY v 3522, and of cephprozyl, cefaclor, cefixime, cefuroxime, cefetamet, cefpodoxime and cefotaxime were determined against Gram-positive and Gram-negative clinical isolates with the NCCLS agar dilution procedures. BAY was the most active drug against Gram-positive organisms. MICs ranged from 0.01 mg/l against group A streptococci to 16 mg/l against S. faecium. Although mean MICs of BAY against methicillin-resistant S. aureus and S. epidermidis were between 0.9-1.8 mg/l, respectively, such strains showed typical heteroresistance in population studies. In addition, the biochemical correlate of methicillin-resistance, the PBP-2', showed similar low affinity to BAY as methicillin. beta-lactamase-producing H. influenzae and B. catarrhalis were inhibited by 2-8 and 0.25-2 mg/l, respectively, whereas non-producers were inhibited by 0.25-2 and 0.12-1 mg/l of the drug. The activity of BAY against enterobacteriaceae was rather low. Ampicillin-susceptible E. coli strains were inhibited by 2-8 and resistant strains by 8-32 mg/l. The mean MIC against cephalothin-susceptible K. pneumoniae strains was 2.8, and that against resistant strains 27.4 mg/l. MICs against beta-lactamase-producing enterobacteriaceae determined in broth dilution were 4-8 times higher than those determined in agar dilution. Bactericidal activity was measured in killing-curve experiments at 4 times the MIC. BAY killed equally well as standard control drugs.     

In vitro activity of ceftiofur tested against clinical isolates of Escherichia coli and Klebsiella pneumoniae including extended spectrum beta-lactamase producing strains

In vitro activity of ceftiofur, a cephalosporin used in veterinary practice was compared using ceftriaxone-resistant (producing extended spectrum beta-lactamase (ESBL)) and -susceptible clinical isolates of Esherichia coli and Klebsiella pneumoniae. The ceftriaxone-susceptible isolates exhibited a lower range of ceftiofur MICs (MIC50, 0.5 mg/l, MIC90 1.0 mg/l). Those isolates known to produce an ESBL were also resistant to ceftiofur (MIC50, > or = 32 mg/l). The latter isolates were also less susceptible to other comparator drugs (cefquinome, gentamicin and trimethoprim/sulphamethoxazole) in contrast to the ceftriaxone-susceptible strains. The clinical isolates showed high correlation between ceftriaxone and ceftiofur MICs (y = 2.6 + 0.89x, r = 0.95). Using the current ceftiofur susceptible breakpoint (< or = 2 mg/l) used for veterinary practice (respiratory tract pathogens), the ESBL-producing strains of E. coli and K. pneumoniae could be accurately separated from susceptible strains. This ceftiofur breakpoint MIC corresponds to the National Committee for Clinical Laboratory Standards ESBL screening concentration for ceftriaxone set at < or = 1 mg/l = negative for ESBL production. Ceftiofur was also observed to be very active in vitro against ampicillin-resistant, non-ESBL producing enteric isolates. This new cephem appears to be very potent against the tested Enterobacteriaceae and of potential wide clinical veterinary utility.     

In vitro activity of four fluoroquinolones against clinical isolates of Pseudomonas aeruginosa determined by the E test

Ciprofloxacin, levofloxacin, ofloxacin, and trovafloxacin were tested by the E-test against 100 clinical isolates of Pseudomonas aeruginosa. Ciprofloxacin was the most active of the tested agents with 82% of isolates having a MIC 8). Levofloxacin and trovafloxacin had nearly identical potency: 75% and 76% of the isolates were inhibited by 8 for levofloxacin; 0.19->8 for trovafloxacin). Ofloxacin was the least active of the four quinolones, with 43% of the isolates having a MIC >2 mg/l. All isolates resistant to ciprofloxacin were also resistant to the other agents, i.e. resistance to ciprofloxacin predicted resistance to all the quinolones tested in every case. This data demonstrates that fluoroquinolones are active agents against P. aeruginosa. In vitro susceptibility testing, however, is crucial to assess the resistance pattern in any specific location and for each individual agent.     

In vitro activity of ertapenem (MK-0826) against multi-drug resistant Streptococcus pneumoniae compared with 13 other antimicrobials

We tested ertapenem (MK-0826), a new carbapenem, and 13 other antimicrobials by microbroth dilution against 102 isolates of Streptococcus pneumoniae, selected to include organisms resistant to a variety of drug classes. Ertapenem MICs ranged from < or =0.008 to 4 mg/l, MIC(50)=0.5 mg/l, and MIC(90)=2 mg/l. Based on MIC(90), ertapenem potency was 4-fold greater than cefuroxime, 2-fold greater than amoxycillin/clavulanate, =penicillin, 2-fold less than meropenem and ceftriaxone, and 4-fold less than imipenem. Other drug classes including macrolides, tetracycline and fluoroquinolones were less potent overall than the carbapenems. Linezolid (MIC(90)=1 mg/l) was the only agent tested for which all isolates were fully susceptible. Activity of ertapenem decreased as MICs to penicillins, cephalosporins, other carbapenems and macrolides increased. Isolates resistant to clindamycin, tetracycline or fluoroquinolones showed no obvious decrease in ertapenem activity when compared with susceptible isolates with the majority of isolates resistant to these drug classes inhibited by ertapenem at concentrations less than 1 mg/l. Ertapenem may prove useful as an alternative to ceftriaxone and other agents in the treatment of community-acquired pneumonia (CAP) due to S. pneumoniae, including infections caused by organisms with reduced susceptibilities to other antimicrobial agents.     

Differential antimicrobial susceptibility between human and chicken isolates of vancomycin-resistant and sensitive Enterococcus faecium

To compare the differential antimicrobial susceptibilities of Enterococcus faecium from humans and whole chicken carcasses, MICs of 12 antimicrobial agents were determined for 54 clinical-isolates (31 vancomycin-resistant [VREF]) and 60 chicken-isolates (29 VREF). Chicken VREF were slightly but consistently more resistant to vancomycin, teicoplanin and avoparcin, compared with human VREF (P<0.01). MICs of LY333328 were 相似文献   

Mupirocin resistance among Malaysian isolates of methicillin-resistant Staphylococcus aureus

Four hundred methicillin-resistant Staphylococcus aureus strains (MRSA) from different geographical areas in Malaysia were tested for mupirocin susceptibility using minimum inhibitory concentration (MIC) determination. The majority of these strains (98.75%) were susceptible to mupirocin with MICs of < or = 4 mg/l. Fifty-percent of these strains had MICs of 0.125 mg/l or less while 90% of the strains had MICs of 1 mg/l or less. Mupirocin resistance was detected in five strains (1.25%) and one of these (0.25%) had an MIC of 64 mg/l and the other four strains (1%), high-level resistance with MICs > 512 mg/l. Even though the rate of mupirocin resistance in MRSA is still low in Malaysia, its presence calls for a strict policy on mupirocin usage in Malaysian hospitals.     

In vitro activity of newer antibiotics against Corynebacterium jeikeium, Corynebacterium amycolatum and Corynebacterium urealyticum

The in vitro activity of ciprofloxacin, erythromycin, telithromycin, teicoplanin, linezolid and quinupristin-dalfopristin was tested against human derived pathogenic corynebacteria. The MICs of these antibiotics were measured using the agar dilution method against 31 strains of Corynebacterium jeikeium, 58 Corynebacterium amycolatum (including 33 multidrug-resistant strains) and 64 Corynebacterium urealyticum clinical strains. A high resistance rate to ciprofloxacin and erythromycin was found in the three species. Telithromycin was much more active than erythromycin (MIC(90) of erythromycin >or=128 mg/l for all three species; MIC(90) of telithromycin: 4 mg/l for C. jeikeium, 64 mg/l for C. amycolatum and 1 mg/l for C. urealyticum). There were no teicoplanin-resistant (MIC(90) 1, 0.5 and 1 mg/l, respectively) or linezolid-resistant strains (MIC(90) 1, 0.2 and 0.5 mg/l, respectively). Quinupristin-dalfopristin was active against most strains with an activity similar to linezolid, but three C. jeikeium and one C. amycolatum showed MICs >or=4 mg/l. Telithromycin showed much better activity against corynebacteria than older macrolides. Synercid and linezolid were active against most isolates tested, including multidrug resistant strains.     

Activity of telithromycin against erythromycin-susceptible and -resistant Streptococcus pneumoniae isolates from adults with invasive infections

A telithromycin (TEL) kill-kinetics study was conducted with 120 clinically significant Streptococcus pneumoniae isolates (60 susceptible and 60 highly resistant to erythromycin). Time–kill curves were performed using different antibiotic concentrations. The minimum inhibitory concentrations (MICs) of TEL were low for both erythromycin-susceptible (MIC ≤ 0.016 mg/L) and erythromycin-resistant strains (MIC ≤ 0.25 mg/L). TEL showed 99.9% killing of all erythromycin resistant strains at 18–24 h of incubation. Even for strains with erythromycin MICs ≥ 64.0 mg/L, TEL was uniformly bactericidal at 0.25 mg/L.     

E-test试条对异质性耐万古霉素葡萄球菌的检测

目的 探讨E—test对异质性耐万古霉素葡萄球菌的检测价值。方法 从连续接触万古霉素的脑心浸液琼脂(BHIA)平板上挑取万古霉素异质性耐药葡萄球菌苗株，应用万古霉素E—test试条、药敏纸片和琼脂平板对倍稀释法测定药敏结果。结果 E—test检测的对万古霉素异质性耐药葡萄球菌MRSHl09，MRSH2，MRSH13，MRSH31，MRSH60，MRSHl08，MRSH73，MRSH97，MRSH102的MIC依次为：16、24、48、48、16、32、24、24mg/L，其中耐药7株占77．8％(7/9)，中介2株占22．2％(2/9)；琼脂对倍稀释法的MIC为：16、32、64、32、16、32、32、16、32mg/L，耐药6株占66．7％(6/9)，中介3株占33．3％(3/9）；药敏纸片直径依次为：14、12、10、11、10、15、13、10，13mm，敏感率为11．1％(1/9)。结论 E—test可以便捷直观地鉴定对万古霉素异质性耐药葡萄球菌的药敏结果，与琼脂平板对倍稀释法接近，优于纸片法。     

In vitro activity of 15 antimicrobial agents against clinical isolates of Clostridium difficile in Kuwait

A total of 73 clinical isolates of Clostridium difficile isolated from stool/rectal swabs of patients admitted to the intensive care units at Mubarak Hospital, Ibn Sina Hospital Burn unit and Haematology wards at the Kuwait Cancer Control Centre, were investigated for their susceptibility to 15 antibiotics using the Etest. Amoxycillin-clavulanic acid, ampicillin, meropenem, metronidazole, penicillin, piperacillin, piperacillin/tazobactam, teicoplanin and vancomycin had excellent activities with MIC(90)s of 0.38, 0.5, 1, 0.19, 1.5, 2, 3, 0.25 and 0.75 mg/l, respectively. Of the 73 C. difficile isolates, 86% were resistant to imipenem (MIC(90) >32 mg/l) and almost 97% were resistant to trovafloxacin (MIC(90)>256 mg/l). Forty eight percent of the isolates were resistant to clindamycin. A total of 18 isolates were highly clindamycin-resistant with an MIC of >256 mg/l; 10 of these were toxin producers. Multiple antibiotic resistance (two or more antibiotics) was noted in 63 isolates. These were more common among the toxigenic strains than the non-toxigenic strains by a ratio of 2.5:1.     

High incidence of antifungal drug resistance in Candida tropicalis

Drug resistance among yeasts is an increasing problem. Isolates of Candida krusei and Candida glabrata are recognized as having reduced susceptibility to fluconazole and resistance to this drug has also arisen in Candida albicans isolated from AIDS patients on long term azole therapy. Candida tropicalis (CT) is being increasingly isolated from human disease and is associated with invasive infection, however, data regarding this organism's drug susceptibility is limited. We report our findings on 60 isolates of CT isolated from patients with serious infection in the North West of England. Over 60% of isolates were from adult Intensive Care Unit (ICU) patients, and almost half were from the respiratory tract. Susceptibility to fluconazole, flucytosine, itraconazole and ketoconazole were tested by standardised methods - 48% of the isolates were resistant to fluconazole (MIC > 12.5 mg/l), and 10% had intermediate susceptibility (MIC 6.25–12.5 mg/l). For flucytosine 17% of isolates were resistant (MIC > 8 mg/l) and 22% had intermediate susceptibility (MIC 2–8 mg/l). Three isolates were resistant to both drugs. For itraconazole 17% of isolates were resistant (MIC > 1 mg/l), and 12% showed intermediate susceptibility (MIC 0.5–1 mg/l). Resistance to ketoconazole was seen in 33% of isolates (MIC > 1 mg/l) and 10% showed intermediate susceptibility (MIC 0.5–1 mg/l). Differences in the degree of cross resistance between the azole drugs was observed. Candida tropicalis should be added to the list of yeasts in which drug resistance is commonly found. Given the high invasiveness of Candida tropicalis, its affinity for patients on ICU and the high incidence of drug resistance in this species, identification and susceptibility tests should be performed on all yeast isolates from patients on ICU.