Activity of caspofungin and voriconazole against clinical isolates of Candida and other medically important yeasts by the CLSI M-44A disk diffusion method with Neo-Sensitabs tablets

In vitro activity of caspofungin and voriconazole against 184 clinical isolates of Candida and other medically important yeasts in comparison with that of fluconazole, ketoconazole, itraconazole and amphotericin B was determined by using a disk diffusion method (Neo-Sensitabs) standardized according to the recommendations of the CLSI documents M44-A and M44-S1 (same medium: Mueller-Hinton plus methylene blue; inoculum and minimal inhibitory concentration/zone breakpoints). Seventy-two percent of clinical isolates were susceptible to caspofungin, 23.6% showed an intermediate susceptibility (most of them were Candida parapsilosis) and 4.3% were resistant (values for Candida spp. were 71.2, 23.8 and 5%, respectively). For voriconazole, 96.7% of clinical isolates were susceptible and 3.3% were resistant (Candida spp.: 96 and 3.8%, respectively). Both caspofungin and voriconazole showed high activity against a wide variety of clinically important yeasts.

In vitro activity of voriconazole against dermatophytes, Scopulariopsis brevicaulis and other opportunistic fungi as agents of onychomycosis

Using a reference microdilution method, we studied the antifungal susceptibility to voriconazole and fluconazole of 304 clinical isolates from four species of onychomycosis-causing dermatophytes, 196 isolates of dermatophytes not related to nail infection as well as Scopulariopsis brevicaulis, Fusarium spp. and Scytalidium dimidiatum. Results showed a high antifungal activity of voriconazole against dermatophytes (geometric mean minimal inhibitory concentration (MIC)=1.14 microg/mL; MIC for 50% of the organisms (MIC(50))=0.062 miccrog/mL; MIC for 90% of the organisms (MIC(90))=0.25 microg/mL). For S. brevicaulis, the in vitro activity of voriconazole was considerably lower (geometric mean MIC=8.52 microg/mL; MIC(50) and MIC(90)=16 microg/mL). Although voriconazole is not among the drugs recommended for the management of onychomycosis, it can be a useful alternative for recalcitrant infections.

In vitro antifungal susceptibility testing of filamentous fungi with Sensititre Yeast OneTM

Sensititre is a colorimetric microdilution method for in vitro antifungal susceptibility testing based on the M27-A document (National Committee for Clinical Laboratory Standards) for yeasts. Difference between both methods is the presence of Alamar-blue and RPMI 1640 (glucose 2%) as culture medium. Antifungal susceptibility to amphotericin B, fluconazole, itraconazole, ketoconazole and flucytosine, 100 opportunistic filamentous fungi (Aspergillus spp., Fusarium spp., Scedosporium spp.) obtained from pathological samples was determined by the Sensititre method. Induction to conidium and sporangiospore formation at 35 degrees C was used to get inoculum and plates were covered by 1 ml of saline and suspensions were made by gently probing by a sterile loop. Optical densities of the conidial suspensions were adjusted to 80-82% transmittance for Aspergillus spp. and 68-70% for the rest of strains tested. Final inoculum concentration size was 0.4 x 10(4)-5 x 10(4) CFU ml(-1). Readings were made at 72 h of incubation at 35 degrees C; amphotericin B and itraconazole was active against Aspergillus fumigatus with CMI90 1 and 0.5 microg ml(-1), respectively, opposite to Scedosporium prolificans and Scedosporium apiospermum. As it was expected, a CMI90 of 256 microg ml(-1) for fluconazole and CMI90 for flucytosine amounting to 64 g ml(-1) were obtained. Sensititre Yeast One is a useful method and an alternative to reference methods to determine antifungal susceptibility of filamentous fungi for clinical laboratory routine. Correlation with microdilution results is studied. New triazole derivatives should be included as soon as their clinical use will be feasible.

In vitro Antifungal Activity of Sertaconazole Compared with Nine Other Drugs against 250 Clinical Isolates of Dermatophytes and Scopulariopsis brevicaulis

We have tested 250 strains belonging to 15 species of clinically important dermatophytes and Scopulariopsis against ten antifungal drugs using an agar diffusion method (NeoSensitabstrade mark, Rosco, Taastrup, Denmark). Some of the experimental factors were adapted to dermatophyte development, such as temperature (28 vs. 35 degrees C) and time of incubation (2-5 days vs. 21-74 h). The antifungals used are itraconazole, ketoconazole, miconazole, clotrimazole, sertaconazole, terbinafine, tioconazole, fluconazole, isoconazole and econazole. Except for fluconazole, all the drugs tested have shown to be highly effective, especially sertaconazole and terbinafine. Percentages of susceptibility ranged between 94% for terbinafine, 87.6% for sertaconazole and 86.4% clotrimazole; 81.6% econazole; 42.8% fluconazole; 57.2% isoconazole; 78.4% itraconazole; 74.4% ketoconazole; 73.3% miconazole, and 85.2% for tioconazole. Percentages of resistance were similar between sertaconazole and terbinafine (4%) but in contrast to the 48% obtained for fluconazole.

[Is amphotericin B active against dermatophytes and Scopulariopsis brevicaulis?]

The in vitro antifungal activity of amphotericin B was compared with that of griseofulvin, ketoconazole, clotrimazole and terbinafine in 193 clinical isolates of dermatophytes and Scopulariopsis brevicaulis. An agar diffusion method was used (NeoSensitabs) to categorize the susceptibility of the isolates as susceptible, intermediate or resistant to the antifungal agents. Using this method and following a standardized protocol adapted to the growth conditions of the dermatophytes and the opportunistic mold S. brevicaulis (inoculum size, temperature and time period of incubation), it was found that the in vitro susceptibility rates were 72%, 94.3%, 81.9%, 72% and 86% for amphotericin B, terbinafine, griseofulvin, ketoconazole and clotrimazole, respectively. Resistance percentages were 12.4%, 3.6%, 18.1%, 10.4% and 4.1% for the same antifungal agents. Amphotericin B showed no antifungal activity against S. brevicaulis; its activity against dermatophytes was similar to that of ketoconazole, and lower than that for clotrimazole and terbinafine.

Ciclopiroxolamine: in vitro antifungal activity against clinical yeast isolates

The in vitro susceptibility of 225 clinical isolates of yeasts to ciclopiroxolamine (CPO) was compared with that of clotrimazole, econazole, ketoconazole, miconazole, tioconazole, fluconazole, itraconazole and nystatin using a standardized agar diffusion method (NeoSensitabs). Two hundred and eight strains of yeasts comprising 16 species of Candida and 22 strains belonging to other yeast genera were tested. One strain (0.4%) was resistant, four strains (1.8%) of intermediate susceptibility and 220 strains (97.3%) susceptible to CPO. More strains were susceptible to CPO than to the other antifungals studied. Susceptibility patterns of antifungal agents were not linked to species. The in vitro antifungal susceptibility profile of CPO was better than topical azole derivatives or fluconazole and itraconazole against a wide variety of clinically important yeasts.

[Activity of itraconazole against clinical isolates of Aspergillus spp. and Fusarium spp. determined by the M38-P NCCLS method]

The antifungal activity of itraconazole was studied in 101 clinical isolates of Aspergillus fumigatus, A. flavus, A. niger, A. terreus, A. nidulans, A. candidus, A. glaucus, A. clavatus, Fusarium solani, F. oxysporum and F. semitectum. The minimum inhibitory concentrations (MIC) were determined according to the protocol of the M38-P National Committee for Laboratory Standards (NCCLS) document using a microdilution method in 1640 RPMI liquid medium (visual reading at 48 and 72 h incubation). In general, the MIC did not vary with time of incubation, except in a Z. fumigatus strain in which the MIC went from 2 to 16 mg/l. The geometric mean of the MIC and MIC(90) of itraconazole for Aspergillus spp. was 0.44 mg/l and 0.5 mg/l, respectively; and for Fusarium spp. it was 14.1 mg/l and 16 mg/l, respectively. With 0.5 mg/l 75% of the Aspergillus spp. strains were inhibited, and 100% of these strains were inhibited with 2 mg/l. A. niger and A. fumigatus were the most resistant species (MIC(90) 2 mg/l). The MIC of all the Fusarium strains essayed was between 4 and 16 mg/l.

Comparative in vitro antifungal activity of amphotericin B lipid complex, amphotericin B and fluconazole

Amphotericin B (AMB) is considered the gold standard in the treatment of serious systemic mycoses in spite of its nephrotoxicity and adverse effects. Association with lipids enables larger doses of AMB to be given with a longer t((1/2)) and C(max), without the toxic effects at lower concentrations. Liposome-encapsulated AMB shows a lower affinity for mammalian cells and improves V(d), thus decreasing toxicity. Amphotericin B lipid complex (ABLC) is an AMB formulation associated with a biodegradable phospholipid matrix (5% molar) from which the drug is released by cell phospholipases. ABLC is recommended for serious mycoses refractory to conventional antifungal therapy or when AMB is contraindicated. We compared the in vitro antifungal activity of ABLC, AMB and fluconazole (FLZ) against 328 strains of clinically significant opportunistic fungi using a microdilution method (NCCLS, M-27A). 64.9% of the yeasts were inhibited by MIC of ABLC </= AMB resulting in a similar or slightly superior efficacy compared to AMB when tested against Candida albicans, C. glabrata, C. guilliermondii, C. parapsilosis and C. tropicalis. Effectiveness against C. krusei was lower for ABLC (5.99 microg/ml for ABLC, 1.58 microg/ml for AMB). However, for Aspergillus fumigatus, the activities of AMB and ABLC were 1.62 and 2.46 microg/ml, respectively; A. niger 0.72 microg/ml, 0.76 microg/ml (ABLC and AMB, respectively); A. clavatus, A. candidus, A. tenuissima, A. corymbifera and Exophiala jeanselmei, Scedosporium spp. and Miceliophtora spp. showed a low susceptibility to both AMB formulations. ABLC is a useful alternative to AMB or FLZ for the treatment of severe fungal infections, due to the broad spectrum of antifungal actions observed in this study.

[The prevalence of methicillin-resistant Staphylococcus aureus phagotype 95 in the Hospitales Vall d'Hebron of Barcelona]

BACKGROUND

In our hospital endemic methicillin resistant Staphylococcus aureus (MRSA) has been documented since 1971, with epidemic and interepidemic periods. During these years phage groups I, I-III, and non-typable were found by the international set of phages Phage group 95 (F95) was unusual between 1986 (when phage typing was first available) and 1991, with prevalence of 5.2% (mean), and 100% of sensibility to methicillin. In November 1991 appeared the first MRSA F95 strain, and its prevalence has been increasing until 1997.

MATERIAL AND METHODS

We have studied 133 strains of MRSA F95 isolated from 87 patients, 39 of them hospitalized in the General Hospital (HG), 38 in Traumatology Hospital (HT) and 8 in the Children's Hospital (HI). Two of these patients had successive stancies in HG and HT. Antimicrobial susceptibility was determined by the disk diffusion method and microdilution to check oxacillin resistance. Moreover these method we have maked: detection of mecA, phage typing with the international set of phages and study of the PGFE patterns by digestion of chromosomic DNA with Smal.

RESULTS

The percentage of methicillin resistance in F95 strains was increased since the appear of the first strain between 8.3% in 1991 to a maximum of 76.9% in 1995, we had a descens to 13.7% in 1996 but 1997 can back to augment it to 72.5%. MICs for oxacillin of these strains were low (< or = 64 mg/l to 87.4% of strains), and all of them were mecA positive, 78.1% of them were resistant to macrolides, 96.5% to tobramycin and 84.9% to quinolones, but only 10.5% to gentamicin, 4.7% were resistant to cotrimoxazol, 1.2% to fosfomycin and 2.5% to rifampin. All of them were sensible to doxycycline, and vancomycin. The pulse field gel electrophoresis showed 7 restriction patterns in MRSA F95, 73.8% of strains correspond to one of them (B), spreading from the spinal cord injury unit and prevalent in HT; and 10.8% to another (C), the first that appear, spreading from the neurosurgical unit and with high prevalence in HG. 6.9% has pattern J a B subtype that appear in broth HG and HT. Pattern E is prevalent in HI it was spread from neonatology unit.

CONCLUSIONS

The emergence in a Center with endemic resistance of new strains of MRSA, not all of them of the same clone, with characteristic resistance pattern to antibiotics and in convivence with other phage groups is one demonstration of genetic variability of SAMR in our entorn.

In-vitro antifungal activity of liposomal nystatin in comparison with nystatin, amphotericin B cholesteryl sulphate, liposomal amphotericin B, amphotericin B lipid complex, amphotericin B desoxycholate, fluconazole and itraconazole

The in-vitro susceptibilities of 120 clinical isolates of yeasts to liposomal nystatin were compared with those to amphotericin B lipid complex (ABLC), liposomal amphotericin B (LAB), amphotericin B cholesteryl sulphate (ABCD), amphotericin B desoxycholate, nystatin, fluconazole and itraconazole. Yeast isolates examined included strains of Candida albicans, Candida parapsilosis, Candida glabrata, Candida krusei, Candida guilliermondii, Candida tropicalis, Candida kefyr, Candida viswanathii, Candida famata, Candida rugosa, Rhodotorula rubra, Trichosporon spp., Cryptococcus laurentii and Cryptococcus neoformans. The mean MICs for all strains examined were: liposomal nystatin 0.96 mg/L; nystatin 0.54 mg/L; ABLC 0.65 mg/L; LAB 1.07 mg/L; ABCD 0.75 mg/L; amphotericin B 0.43 mg/L; fluconazole 5.53 mg/L; and itraconazole 0.33 mg/L. No significant differences were seen between the activity of liposomal nystatin and the polyene drugs or itraconazole, but liposomal nystatin was more active than fluconazole. MICs were lower than the reported blood concentrations following therapeutic doses of this drug, indicating the potential for a therapeutic use of liposomal nystatin in humans. These results indicate good activity in vitro against medically important yeasts, which compares favourably with the activities of other currently available antifungal drugs. Liposomal nystatin may have a role in the treatment of disseminated and systemic mycoses.

[Determination of the in vitro antifungal susceptibility of clinically important yeasts using the Sensititre system]

Using Sensititre (AccuMed, USA) we studied the in vitro antifungal activity of amphotericin B, fluconazole, itraconazole, ketoconazole and 5-fluorocytosine against 250 clinical yeast isolates taken from different hospitals, including Candida (151 C. albicans, 15 C. krusei, 14 C. parapsilosis, 11 C. tropicalis, 10 C. glabrata, 4 C. guilliermondii, 3 C. rugosa, 2 C. viswanathii, 2 C. famata and 2 C. kefyr), Cryptococcus (32 C. neoformans and 1 C. laurentii), Trichosporon (2 isolates) and Rhodotorula rubra (1 isolate). All the strains were susceptible to amphotericin B and showed an MIC <1 mg/l. The susceptibility of C. albicans (MIC(90) <256 mg/l), C. krusei (MIC(90) <64 mg/l), C. glabrata (MIC(90) <64 mg/l) and C. neoformans (MIC(90) 32 mg/l) to fluconazole was lower (14% isolates being resistant and 16.8% susceptible depending on the dose). The largest number of strains resistant to itraconazole was observed in C. albicans and C. glabrata (17.2% resistant and 24% susceptible and susceptible depending on the dose, respectively). Ketoconazole and 5-fluorocytosine were not effective in vitro against 12.8% and 2%, respectively, of all the isolates studied. Nine C. krusei and seven C. neoformans (12.9%) showed dose-dependent susceptibility to 5-fluorocytosine.

[Epidemiology of Serratia marcescens between 1987 and 1995 at Vall d'Hebron Hospital]

BACKGROUND

Nosocomial infection have a relative high prevalence, which is necessary to reduce in order to improve the quality of patient care. The aims of this work is to study the behaviour of Serratia marcescens in our hospital as between 1987 and 1995.

METHODS

Between February 1987 and March 1995 we detected 679 isolates of Serratia marcescens in 504 patients. We used serotype as first marker and phagotype as second, and evaluation of PGFE as a discriminator of doubtful strains was done.

RESULTS

35.8% of the strains were from the respiratory tract, 37.2% from urinary tract; and 11.7% were isolated in blood culture, among them 23.3% came form children younger than 7 years. We noticed a tendency to decrease the number of isolates along the studied period. The most frequent serotypes were O:6, O:3 and O:2; representing the 36.0% of the total. Serotypes O:6;14, O:4, O:5, O:11 and polyagglutinables accounted for 37% of the total. The frequency was variable from year to year, and the predominant serotypes were different in every one of the hospitals in which the center is divided. A 60% of the patients were hospitalized in the General Hospital Vall d'Hebron building, in ICU (20%) and in chirurgical services (25%). Ninety-six patients had more than one isolate, 91 of them (94.8%) can be classified by phenotypic test. The PFGE is discriminatory in three of the five unclassificable isolates. In more than 35% of the patients the strains isolated along the time are different. The 66.7% of the patients acquired Serratia strains in the same admission, and in some cases with few days of difference. We detected 17 cross infections, predominantly in ICUs. With PFGE we could discriminate isolates which produced cross infections between patient who are not in the same hospital.

CONCLUSIONS

Although the prevalence of Serratia marcescens is diminishing, it is able to produce crossed infections that, in general, affected few patients. The serotype and phagotype discriminate 94.8% of isolates. The PFGE is high discriminatory and reproducible, only 6.8% of the 44 strains tested by this method can not be typed.

Effectiveness of cloxacillin with and without gentamicin in short-term therapy for right-sided Staphylococcus aureus endocarditis. A randomized, controlled trial

BACKGROUND

It is often difficult to administer extended antibiotic therapy in the hospital for right-sided Staphylococcus aureus endocarditis. Although the effectiveness of single-drug therapy given for 4 to 6 weeks and that of two-drug therapy given for 2 weeks have been shown, no data are available on the effectiveness of short-course single-drug therapy.

OBJECTIVE

To compare the efficacy of cloxacillin alone with that of cloxacillin plus gentamicin for the 2-week treatment of right-sided S. aureus endocarditis in intravenous drug users.

DESIGN

Open, randomized study.

SETTING

An academic tertiary care hospital in Barcelona, Spain.

PATIENTS

90 consecutive intravenous drug users who had isolated tricuspid valve endocarditis caused by methicillin-susceptible S. aureus, had no allergy to study medications, and had no systemic infectious complications that required prolonged therapy. An efficacy subset consisted of 74 of these patients who did not meet an exclusion criterion.

INTERVENTION

Cloxacillin (2 g intravenously every 4 hours for 14 days) alone or combined with gentamicin (1 mg/kg of body weight intravenously every 8 hours for 7 days).

MEASUREMENTS

Clinical or microbiological evidence of active infection after 2 weeks of therapy, relapse of staphylococcal infection, or death.

RESULTS

In an analysis of the efficacy subset, treatment was successful in 34 of the 38 patients who received cloxacillin alone (89% [95% CI, 75% to 97%]) and 31 of the 36 patients who received cloxacillin plus gentamicin (86% [CI, 71% to 95%]). Three patients died: one in the cloxacillin group and two in the combination therapy group. Of the 37 patients who completed 2-week treatment with cloxacillin, 34 (92%) were cured, and 3 (8%) needed prolonged treatment to cure the infection. Of the 34 patients who completed 2-week treatment with cloxacillin plus gentamicin, 32 (94%) were cured and 2 (6%) required treatment for 4 weeks. One patient in the combination group had relapse.

CONCLUSIONS

A penicillinase-resistant penicillin used as single-agent therapy for 2 weeks was effective for most patients with isolated tricuspid endocarditis caused by methicillin-susceptible S. aureus. Adding gentamicin did not appear to provide any therapeutic advantages. Additional studies to confirm the therapeutic equivalence of short-course therapy with penicillinase-resistant penicillin alone and therapy with combined regimens are warranted.

[Treatment and outcome of pneumococcal meningitis in adults. Study of a recent series of 70 episodes]

BACKGROUND

Pneumococcal meningitis (PM) is an infection with high morbidity and mortality. The aim of this study was to evaluate the most relevant clinical, epidemiologic and evolutive characteristics of a recent series of adult patients with this disease.

METHODS

Over a period of 10 years all the patients with PM diagnosed by isolation of this microorganism in the cerebrospinal fluid (CSF) were evaluated from a clinical, therapeutic and evolutive points of view. The impact of the new therapies in the disease and the variables associated with mortality were analyzed.

RESULTS

Seventy episodes of PM were diagnosed, 60% being found in patients over the age of 50 years. The male/female relationship was 2/1. Fifty-three percent of the patients had other underlying diseases. Acute otitis media (AOM) was the source in 34% of the cases, in 11% the patients had a fistula of CSF and in 9% a pneumonia. At the time of diagnosis 74% of the patients had some degree of reduction in the level of consciousness and in 40% of the episodes the presence of neurologic local manifestations were observed. A decrease in sensitivity to penicillin was observed in 33% of the microorganisms isolated. Third generation cephalosporins were used as initial treatment in 57 episodes and penicillin in other 11 episodes. Adjuvant treatment with dexamethasone, mannitol and/or diphenylhydantoin was administered in 54% of the patients. Overall mortality was 23%: the factors associated with an unfavourable evolution were the existence of underlying disease, deep alteration in the level of consciousness at the time of diagnosis, the coexistence of pneumonia and the absence of adjuvant therapy.

CONCLUSIONS

Mortality in pneumococcal meningitis is high. The most relevant risk factor is the initial degree of consciousness. Adjuvant therapies probably determine a reduction in the rate of mortality.

Investigation of an outbreak of nosocomial infection due to a multiply drug-resistant strain of Pseudomonas aeruginosa

A nosocomial outbreak of Pseudomonas aeruginosa infections which occurred in the Urology Service of a large city hospital was studied. A case-control methodology was used to analyse patients' characteristics and the main risk factors of all cases with a positive culture during the period between March 1987 and March 1988. The usefulness of factor analysis in the definition of a case was examined. There were 74 infections of which 35 (47.3%), had a nosocomial origin. The outbreak took place in December 1987, with a peak incidence of infections of 10.5%, compared with a 2.2% frequency during the preceding months (P less than 0.005). Six of the nine infections occurring in that month, were caused by strains resistant to ticarcillin and gentamicin. The epidemic cases had longer hospital stays than the non-epidemic cases (P less than 0.038) and occurred more frequently in a specific area of the hospital (P less than 0.001). The odds ratio for resistance to gentamicin was 15 (P less than 0.018) and that of resistance to ticarcillin, 127 (P less than 0.0001). Our results suggest that inaccurate case definitions may produce misleading conclusions. Factor analysis appears to be a useful analytical tool when defining a case.

[Enterococci: high level of resistance to aminoglycosides in strains isolated by different laboratories in Catalonia]

We study 583 strains of enterococci isolates by 19 laboratories from Catalonia: 546 E. faecalis (93.5%), 34 E. faecium (6%) and 3 E. durans (0.5%). We inoculated all the strains in Müeller-Hinton agar with 2,000 mg/l of one of the following aminoglycoside: gentamicin, tobramycin, amikacin, streptomycin and kanamycin. Global incidence of high-level resistance was 9.4% to gentamicin, 7.3% to tobramycin, 0.2% to amikacin, 30.3% to streptomycin and 37.7% to kanamycin, with important changes in regard of procedence.

[Pneumococci resistant to penicillin]

Between January of 1983 and December 1984, 11 strains of pneumococci resistant to penicillin were isolated, from a total of 46 strains studied with clinical signification, thus accounting for 23.9%. In nine cases (19.5%) pneumococci showed partial resistance to penicillin and in two strains (4.3%) resistance was total. Pneumococcal disease in our 11 patients was demonstrated by blood culture in 7 cases and by culture of the CSF, in 4. Diagnosis of the patients were as follows: 4 sepsis in immunosuppressed host, 2 bacteremia without an evident focus, 1 pneumonia, 3 meningitis and 1 ventriculitis. Vancomycin and rifampin are the most active in this cases. Some of the new cephalosporins of the third generation (cefotaxime and ceftriaxone) and cefuroxime have a good activity in vitro and a good passage to the CSF.

Acute renal insufficiency in the rabbit by glycerol

The appearance of an acute renal insufficiency in the rabbit, after glycerol injection (10, 13 or 15 ml/kg of a 50% solution) is investigated. After a 24 hours of intoxication, especially in the ten following days, cylinders, erythrocytes and renal cells appear in the urine sediment. Proteinuria appears after 24 hours and practically disappears after 72 h. Glucosuria persists from 24 hours to 6 days. Haemoglobinuria is intense after 24 and 48 hours and persists slightly about 6 days. Na, K and Cl elimination in urine diminishes clearly in all animals. Plasma K increases in non-surviving animals and does not change in those surviving. Plasma Na does not change in the dying ones, and decreases in those surviving. In non-surviving animals, pH, pCO2 and CO3H minus decrease sharply. In the surviving ones pCO2 decreases clearly after 24 hours, increasing afterwards slowly to normal values. pH increases, slightly during the first 48 hours, and then neatly during approximately 6 days. Standard CO2H minus does not change during the first 48 hours, increasing afterwards during 6 to 7 days. Histologically, the chief lesion is a vacuolar degeneration of the proximal tubule. The possible mechanisms of such alterations are discussed.