Chemotherapy for enterohemorrhagic Escherichia coli O157:H infection in a mouse model

The aim of this study is to evaluate the therapeutic effect of the antimicrobial agents, fosfomycin (FOM), minocycline (MINO), kanamycin (KM) and norfloxacin (NFLX) in the enterohemorrhagic Escherichia coli (EHEC) infected mouse model which we established previously (Infect. Immun. 62 (1994) 3447-3453). Each of the antimicrobial agents, 1/16 LD(50), was given to the mice per os (p.o. ) or intraperitoneally (i.p.) for 3 days after bacterial inoculation and then we observed their mortality rate for 2 weeks. The mortality rates of mice administered with MINO (p.o./i.p.), KM (p.o.), NFLX (p. o./i.p.) were significantly lower than those of the control group. Both the bacterial number and VT2c level in the feces of the FOM group were lower than those of the NFLX group on day 1, but reversed on day 3. In an in vitro experiment, each of the four drugs in combination with mitomycin C (MMC) caused a more significant decrease in the bacterial number than sole MMC, and they consequently indicated the suppressive effect on the release of VT2c.

[Therapeutic effects of antibiotics against enterohemorrhagic Escherichia coli (EHEC) O157:H7 (O157) infection: in vivo analysis using germfree mice]

Though O157 can cause a life-threatening diseases, the therapeutic protocol using antibiotics for the infection is still controversial. Main reasons for hesitating the uses of antibiotics for the infection is their possibility to enhance the release of verotoxins (VT). We have recently established the mouse model of O157 infection using germfree mice. Using this animal model of O157 infection, we examined therapeutic efficacy of antibiotics. Fosfomycin (FOM) and norfloxacin (NFLX) were selected for in vivo examination, because of their lower MIC under anaerobic condition (MIC:FOM = 0.78; NFLX = 0.10 microgram/ml) than those of the other antibiotics including kanamycin, doxycycline, minocycline, choramphenicol, cefaclor and ampicilin. When germfree BALB/c mice were orally infected with 1 x 10(5)CFU of O157 (clinically-isolated strain, TI001) at day 0, all mice died at 8 to 9 d after the infection. Oral treatment of the mice with FOM (500 mg/kg/d, twice a day) or NFLX (50 mg/kg/d, twice a day) everyday for 5 days starting at 3 hr after the infection significantly improved the survival rate from 0% to 83.3%, and 100%, respectively. VT could not be detected in the feces of the mice in either groups, suggesting that neither of these antibiotics enhanced the release of VT. Interestingly, when FOM treatment was started at 3, 6, 12 or 24 hr after the infection, the survival rate was 100%, 100%, 0% and 0%, respectively. Thus, in conclusion, FOM and NFLX are both useful as the therapeutic agents for O157 infection. However, the treatment should be started in the early phase after the infection.

Fosfomycin tromethamine: single-dose treatment of acute cystitis

Fosfomycin tromethamine is an oral antimicrobial indicated for the treatment of uncomplicated lower urinary tract infections (UTIs). This agent is active in the urine against common uropathogens that are associated with cystitis in women, including organisms resistant to other antibiotics. A single dose of fosfomycin tromethamine is well absorbed and produces a therapeutic concentration in the urine for one to three days. Comparative clinical trials suggest that a single 3.0-g dose of fosfomycin tromethamine is as clinically effective as 7- to 10-day treatment regimens of standard agents such as nitrofurantoin, norfloxacin, and trimethoprim/sulfamethoxazole used to treat UTIs. Fosfomycin tromethamine is well tolerated and appears safe for use during pregnancy. Quality-of-life advantages, such as enhanced compliance and convenience, are also important aspects of fosfomycin tromethamine therapy.

[Pneumoperitoneum with systemic sclerosis]

We report a case of systemic sclerosis (SSc) complicated with benign pneumoperitoneum without apparent pneumatosis cystoides intestinalis (PCI). A 43-year-old woman was admitted to our hospital because of prominent abdominal distension in April 1997. Raynaud's phenomenon has been detected since 1991. She was suffering from recurrent diarrhea, constipation, and subileus. The diagnosis of SSc was made in 1996 based on the sclerosis in her face, forearms, and chest, and hypomotility of the esophagus. On admission, she presented no signs of peritoneal irritation. The laboratory data revealed that white blood cell count was 7,400/mm3 and C-reactive protein was 0.1 mg/dl. Chest and abdominal roentgenograms showed massive free air under the diaphragm, dilatation of small and large intestine, and air-fluid level. PCI was not apparent. Pneumoperitoneum was improved after four weeks with intravenous hyperalimentation. But she presented recurrent severe diarrhea and high fever whenever she tried to take food orally. Klebsiella pneumoniae was proved in her jejunal juice by bacteriologic examination. Intravenous prostaglandin F2 alpha and oral fosfomycin calcium intake made her condition better. Benign pneumoperitoneum without PCI is rarely reported in the patients with SSc. In her condition, weakness of intestinal wall, hypomotility of intestine, unusual bacterial overgrowth, and elevated intraluminal pressure made intraluminal gas go through the wall of the fragile intestine of SSc. As operation of intestine of SSc usually cause miserable outcome, pneumoperitoneum accompanied with SSc even if PCI is apparent or not must be treated with conventional manner while there is no signs of peritoneal irritation.

Efficacy of phosphomycin in the control of Escherichia coli infection of broiler chickens

Seventy-five 25-day-old broilers were divided into three groups: group I unmedicated and challenged with E. coli O78:K80; group F infected and treated with 150 ppm of phosphomycin in their drinking water, and group C acted as a control. Their weights, feed intake, clinical signs, macroscopic lesions, E. coli reisolation, and serum biochemistry were compared. Group F showed fewer symptoms and gross lesions than those from group I while the average daily gain, bodyweight, and feed intake were similar to the control group. E. coli was reisolated in 32 per cent of the livers and spleens from group I, compared with 4 per cent of liver and 8 per cent of spleens from group F. There was an increase in the levels of total protein and globulins in group I but not in group F. These results provide evidence of the therapeutic efficacy of phosphomycin in the control of an experimental E. coli infection in broiler chickens.

How do the newer oral antimicrobials stack up against traditional agents?

As the antibiotic arsenal expands with the development of new oral agents, selecting appropriate therapy is becoming more difficult. What are the therapeutic indications for the newer antimicrobials, and what advantages do they have over traditional agents? Drs Gleckman and De La Rosa discuss current issues related to antibiotic treatment and offer specific recommendations for the best use of the newer agents.

[Severe streptococcal group A infection complicating varicella]

Varicella is a common viral infection which is generally benign in infancy and has a good outcome. It may sometimes be complicated by severe group A streptococcal superinfection.

CASE REPORT

Three days after the beginning of varicella, a previously healthy 2-year-old girl presented with left leg pain, lameness and edema of all four limbs. Toxic shock syndrome occurred, due to beta-hemolytic group A Streptococcus grown from blood culture. Computerized tomography (CT) scan showed a mild effusion involving both hips. Cefotaxim was administered, but the week after magnetic resonance imaging (MRI) showed a necrotizing fasciitis and a lesion of the left leg leading to a patchy femoral diaphysis consistent with osteomyelitis. Joint aspirate culture did not grow. The left leg was immobilized in plaster for 6 weeks and the child was given cefotaxim and fosfomycin parenterally during 30 days, then followed by 45 days of oral amoxicillin. She recovered without sequelae.

CONCLUSION

Group A Streptococcus infection is a dangerous complication of varicella. It must be considered in case of any joint pain occurring during or just after this disease. The choice of the best treatment needs full collaboration between surgeons, radiologists and pediatricians.

A comparison between single-dose fosfomycin trometamol (Monuril) and a 5-day course of trimethoprim in the treatment of uncomplicated lower urinary tract infection in women

This study is a comparison of the microbiological and clinical efficacy of single-dose fosfomycin trometamol therapy and a 5 day course of trimethoprim in the treatment of uncomplicated urinary tract infection in female patients. Urine dip-slide samples were obtained from 547 female patients aged 18-65 by 22 General Practitioners (GPs) participating in the study from 21 centres in the UK. All patients were diagnosed as having a urinary tract infection by their GP on the basis of history and clinical examination. Patients were randomised to receive either single dose fosfomycin trometamol or a 5 day course of trimethoprim in a 2:1 ratio. Patients who had significant bacteriuria (> or = 10(5) c.f.u/ml) at the first visit (300) were included in the microbiological analysis. The two commonest urinary pathogens isolated were Escherichia coli and Staphylococcus saprophyticus. Trimethoprim resistance was more frequent amongst E. coli isolates whereas fosfomycin trometamol resistance was more common amongst S. saprophyticus isolates. Microbiological cure was demonstrated in 83.3% of the trimethoprim treated group and 83% of the fosfomycin trometamol treated group. Persistence of the infecting bacteria was seen in 17% of each treatment arm.

Single-dose treatment of acute cystitis with fosfomycin tromethamine

OBJECTIVE

To review the clinical pharmacology of fosfomycin tromethamine, a new antimicrobial agent for the treatment of uncomplicated lower urinary tract infections (UTIs).

DATA SOURCE

Publications in English on fosfomycin, fosfomycin tromethamine, and fosfomycin trometamol (MEDLINE, 1970-1997), as well as unpublished studies submitted to the Food and Drug Administration (FDA), were reviewed.

STUDY SELECTION

Comparative, randomized, controlled studies were used to analyze the efficacy and safety of fosfomycin tromethamine.

DATA SYNTHESIS

Fosfomycin tromethamine is an oral antimicrobial indicated for the treatment of uncomplicated lower UTIs. This agent is active in the urine against common uropathogens that are associated with cystitis in women, including organisms resistant to other antibiotics. A single dose of fosfomycin tromethamine is well absorbed and produces therapeutic concentrations in the urine for 2-4 days. Comparative clinical trials suggest that a single dose of fosfomycin tromethamine 3.0 g is as clinically effective as 7- to 10-day treatment regimens of standard agents used to treat UTIs, such as nitrofurantoin, norfloxacin, and trimethoprim/sulfamethoxazole. Fosfomycin tromethamine is well tolerated and appears safe to use during pregnancy.

CONCLUSIONS

Fosfomycin tromethamine is the only antimicrobial to be approved by the FDA for single-dose therapy in women with acute cystitis. It is as effective and safe as multidose comparators and appears safe to use during pregnancy. The acquisition cost of this new drug will need to be weighed against the improved compliance and convenience associated with its use in the treatment of uncomplicated UTIs.

[Result of antibiotic therapy for children with Escherichia coli O26:H11 infection]

Between the end of November 1996 and the beginning of March 1997, there was an outbreak of Escherichia coli O26:H11 infection in Asahikawa. The strain produced only verotoxin type 1. The minimal inhibitory concentrations (microgram/ml) of the strain under aerobic condition and those of anaerobic were as follows: chloramphenicol (1.56, 0.78), minocycline (12.5, 3.13), kanamycin (3.13, 25), ampicillin (> 100, > 100), fosfomycin (12.5, 1.56), norfloxacin (0.1, 0.1), and cefaclor (6.25, 3.13). Forty-one episodes of antibiotic therapy to 32 children, who were treated in Asahikawa Kosei Hospital, Asahikawa Municipal Hospital, and Asahikawa Red Cross Hospital, were evaluated bacteriologically. In 26 episodes treated with fosfomycin, the pathogen from stools of 19 were eradicated, 4 were not eradicated, and 3 were isolated again within 2 weeks after the cessation of therapy. Eight episodes treated with norfloxacin and 5 episodes in kanamycin were all eradicated.

[Predictive factors for development of hemolytic uremic syndrome (HUS) and early intensive treatments for prevention of HUS enterohemorrhagic Escherichia coli infection]

Predictive factors for the development of hemolytic uremic syndrome (HUS) were evaluated in 88 inpatients who suffered from enterohemorrhagic E. coli infections in the outbreak in Sakai, 1996. All in- and outpatients received oral or intravenous fosfomycin within acute phase of hemorrhagic colitis, and HUS complicated 1.4% of them. Persistence of bloody stools and diarrhea were longer in HUS patients than in non-HUS patients, but persistence of abdominal pain was not different in either group. Leukocytosis with leukocyte counts over 15,000/microliters and/or elevated CRP level over 2.0 mg/dl at admission, and fever and/or vomiting in the course of hemorrhagic colitis were more frequent in HUS patients than in non-HUS patients. Early intensive treatments including gammaglobulin, urinastatin, aspirin, and dipyridamole were employed in 34 high risk patients for prevention of HUS. These patients were estimated to be at risk of developing HUS because of incomplete HUS, nephropathy, elevated LDH level, thrombocytopenia, or age younger than two years old. These treatments were clinically effective.

Comparison of Five Agents in Protecting the Cochlea Against the Ototoxic Effects of Cisplatin in the Hamster

The purpose of this investigation was to study the ameliorating effects of four agents on cis-platin-induced ototoxicity. Hamsters were given a series of five cisplatin injections either alone or in combination with sodium thiosulfate (STS), diethyldihydrothiocarbamate (DDTC), and S-2(3-aminopropylamino) ethylphosphorothiolc acid (WR-2721), or fosfomycin. Ototoxicity was assessed anatomically by quantifying the extent of cochlear damage with the scanning electron microscope and physiologically with measures of the auditory brain stem response. When administered alone, cisplatin induced widespread loss of outer hair cells (OHCs) along much of the cochlea in the hamster, especially in the basal and middle turns, with an average survival of only 56% of the OHC population. In contrast, inner hair cells resisted cisplatin ototoxicity in the hamster. Thus the ameliorative effects of the different test agents were assessed by counting the number of surviving OHCs in each treatment group and comparing with cisplatin-treated controls. STS provided the most effective protection against the ototoxic effects of cisplatin, yielding 91% survival of OHCs. DDTC also reduced the ototoxic effects of cisplatin, yielding 68% survival of OHCs. Cotreatment with WR-2721 and fosfomycin yielded 45% and 52% OHC survival, respectively, and thus did not provide any chemoprotection. The results closely paralleled those based on auditory brain stem response recordings in that the magnitude of threshold shift was proportional to the amount of OHC loss; also, the amount of threshold shift at each frequency was in good agreement with the pattern of hair cell loss along the cochlear spiral. Thus both histologic and physiologic results suggest that STS and DDTC hold promise for ameliorating the ototoxic effects of cisplatin chemotherapy.

Effect of antimicrobial agents, especially fosfomycin, on the production and release of Vero toxin by enterohaemorrhagic Escherichia coli O157:H7

In 1996, Japan had several large outbreaks of enterohaemorrhagic Escherichia coli (EHEC) O157:H7 infection. We surveyed physicians who examined and treated these patients, and found that most of the patients (95.9%) received antimicrobial agents as treatments, in particular, fosfomycin comprised 84.0% of the prescribed treatment. Since the administration of antimicrobial agents for EHEC infection is under discussion, we also analyzed the effects of 7 antimicrobial agents including fosfomycin on the production and release of Vero toxins (VTs) by EHEC. The addition of fosfomycin into EHEC culture in CAYE broth at 5 h after the start of incubation caused a marked increase of VT1 release and production, as revealed by an immunological toxin assay (RPLA). However, a cytotoxicity assay of Vero cells showed a small increase of biological activity in the specimens treated with fosfomycin because the Vero cell assay reflects total cytotoxicity of VT1 and VT2. These results indicate that further study is necessary before concluding whether antimicrobial agents actually worsen an EHEC infection.

Bactericidal effect of pefloxacin and fosfomycin against Pseudomonas aeruginosa in a rabbit endocarditis model with pharmacokinetics of pefloxacin in humans simulated in vivo

The bactericidal activity of pefloxacin and fosfomycin alone and in combination against Pseudomonas aeruginosa was evaluated in an experimental rabbit endocarditis model after 24 h of treatment. Two strains with intermediate susceptibility to pefloxacin and good susceptibility to fosfomycin were tested. The serum kinetics obtained during administration of 400 mg every 12 h in humans were simulated in the animals using computer-controlled variable-flow infusion. Fosfomycin was administered as a continuous infusion at a constant flow, allowing a steady-state concentration of 47.4 +/- 11.9 mg/ml to be reached in serum. In valvular vegetations, pefloxacin was less bactericidal than fosfomycin, and in combination treatment, it reduced (but did not abolish) the bactericidal effect of fosfomycin. The duration of the pretreatment interval (12-48 h) had a negative effect on the bactericidal activity of both drugs, especially that of fosfomycin.

Cisplatin-induced nephrotoxicity and the protective effect of fosfomycin on it as demonstrated by using a crossover study of urinary metabolite levels

BACKGROUND

Cisplatin induces nephrotoxicity and this study evaluated the protective effect of fosfomycin on it in 11 gynecological cancer patients.

METHODS

The N-acetyl-beta-D-glucosaminidase (NAG), beta 2-microglobulin (beta 2MG), creatinine (uCr) and total protein (TP) levels in a 24-hour urine specimen as well as the blood urea nitrogen (BUN) and serum creatinine (sCr) were measured before and after CAPF chemotherapy alone (control) or with fosfomycin.

RESULTS

The results were statistically analyzed by using the t-test. NAG, beta 2MG, uCr and TP levels increased significantly after chemotherapy in the control patients, but BUN and sCr levels did not change significantly. The NAG level in the control group was twice as high as in the fosfomycin group 8 days after chemotherapy (p < 0.01). The uCr and TP in control patients increased significantly after chemotherapy when compared to those in patients coad-ministered fosfomycin. There were no significant changes in beta 2MG, BUN and sCr levels.

CONCLUSIONS

Cisplatin affected the levels of NAG, beta 2MG, uCr and TP without influencing BUN and sCr levels. Fosfomycin, therefore, may be useful as a supplemental treatment for reducing cisplatin nephrotoxicity, especially proximal tubular damage.

[Severe methicillin-resistant Staphylococcus aureus infections. Emergence of resistance to fusidic acid or fosfomycin during treatment with continuous infusion of vancomycin]

OBJECTIVES

To evaluate the development of resistance to fosfomycin or fucidic acid in severe infections caused by methicillin-resistant Staphylococcus aureus (MRSA) and to assess the relationship with serum levels of vancomycin

METHODS

A retrospective study was performed in patients hospitalized in our intensive care unit during a 3-year period (1993-1995) who were treated for severe MRSA infection with continuous infusion vacomycin and fosfomycin or fucidic acid. We analyzed the development of resistance and serum levels of vancomycin.

RESULTS

During this period, only 20 patients received continuous infusion vancomycin plus fucidic acid or fosfomycin. MSRA resistant to fucidic or fosfomycin developed in 9. Vancomycin serum levels were significantly lower in patients who developed resistance to focidic acid or fosfomycin, both during the first 5 days of treatment (16.68 +/- 1.07 micrograms/ml vs. 22.64 +/- 1.05 mg/ml, p < 0.01) and throughout treatment duration (17.29 +/- 1.07 micrograms/ml vs. 21.85 +/- 0.78 microgram/ml, p < 0.01).

CONCLUSIONS

Our findings confirm that in spite of continuous vancomycin infusion at an initial rate of 2 g/24 h, Staphylococcus aureus resistance to fosfomycin or fucidic acid an develop during ongoing treatment. Vancomycin levels of at least 20 micrograms/ml should be obtained as rapidly as possible.

Fosfomycin tromethamine. A review of its antibacterial activity, pharmacokinetic properties and therapeutic efficacy as a single-dose oral treatment for acute uncomplicated lower urinary tract infections

Fosfomycin tromethamine is a phosphonic acid bactericidal agent with in vitro activity against most urinary tract pathogens. It is particularly active against Escherichia coli, and Citrobacter, Enterobacter, Klebsiella, Serratia and Enterococcus spp. There appears to be little cross-resistance between fosfomycin and other antibacterial agents, possibly because it differs from other agents in its general chemical structure and site of action. In its new formulation as the oral tromethamine salt, fosfomycin has 34 to 41% oral bioavailability, has a mean elimination half-life of 5.7 hours, and is primarily excreted unchanged in the urine. Following a single 3 g oral dose, peak urinary concentrations occur within 4 hours and remain high (> 128 mg/L) for 24 to 48 hours, which is sufficient to inhibit most urinary tract pathogens. In clinical trials in patients with acute uncomplicated lower urinary tract infection, single-dose fosfomycin tromethamine therapy was effective, and comparable with several other antibacterial agents given either as single-dose or multiple-dose treatments [e.g. beta-lactam and fluoroquinolone agents, cotrimoxazole (trimethoprim-sulfamethoxazole), nitrofurantoin and pipemidic acid]. Bacteriological eradication rates of 75 to 90% were achieved 5 to 11 days after therapy, with eradication rates of 62 to 93% 4 to 6 weeks after therapy. In 3 large double-blind comparisons with ciprofloxacin, cotrimoxazole and nitrofurantoin, 99% of fosfomycin tromethamine recipients and 100% of patients receiving comparator agents were considered clinically cured or improved after therapy. Fosfomycin tromethamine is well tolerated, with a low incidence of adverse events. These comprise mainly gastrointestinal symptoms that are transient, mild and self-limiting. Thus, fosfomycin tromethamine achieves high clinical and bacteriological cure rates in patients with acute uncomplicated lower urinary tract infection and is well tolerated. The single-dose administration regimen and favourable US pregnancy category rating of fosfomycin tromethamine should also encourage its use in this indication.

Antimicrobial potentiality of a new beta-lactum antibiotic fosfomycin

Antimicrobial action of penicillin and some of its derivatives including fosfomycin was studied with respect to 225 strains of Gram-positive and Gram negative bacteria. Fosfomycin was found to possess somewhat less activity against Staphylococcus aureus compared with other penicillins; however, it showed powerful activity towards Escherichia coli, Klebsiella spp. and Proteus mirabilis.

In vivo activity and pharmacodynamics of amoxicillin in combination with fosfomycin in fibrin clots infected with highly penicillin-resistant Streptococcus pneumoniae

Using a clinical pneumococcal strain for which MICs were 4, 2, and 32 mg/liter for penicillin, amoxicillin, and fosfomycin, respectively, we studied the efficacies of these antibiotics alone and their combinations in the treatment of prolonged (48-h) experimental fibrin clot infection in rabbits. Treatments were as follows: amoxicillin IV at 20 mg/kg of body weight in one dose (Amo20), 50 mg/kg in one dose (Amo50), or two doses 6 h apart (Amo20 x 2 and Amo50 x 2); fosfomycin IV at a fixed dose of 50 mg/kg in one dose (Fos50) or two divided doses 6 h apart (Fos50 x 2); or the combinations of amoxicillin and fosfomycin with the same schedules. Maximum concentrations in clots were 2.03 +/- 1.02 and 2.13 +/- 0.33 mg/liter for Amo20 regimens, 3.7 +/- 1.9 and 4 +/- 1.3 mg/liter for Amo50 regimens, and 24 +/- 7 and 40 +/- 8 mg/liter for fosfomycin regimens, respectively. The mean half-lives of elimination from clots were between 2 and 3 h for amoxicillin regimens and between 5 and 7 h for fosfomycin. We observed the highest bacterial reductions (log10 CFU/gram) for Amo50 in two divided doses with or without fosfomycin. A significantly higher bacterial reduction than that with each monotherapy was observed when Amo20 was combined with fosfomycin in either one dose or two doses 6 h apart (0.16 +/- 0.8 and 1.64 +/- 1.6 log10 CFU/g for Amo20 in one and two doses, respectively, and 0.93 +/- 0.81 and 0.61 +/- 0.56 log10 CFU/g for fosfomycin in one and two doses, respectively, versus 3.46 +/- 1.26 and 3.16 +/- 1.31 log10 CFU/g for Amo20 plus fosfomycin in one and two doses, respectively [P < 0.001]). A time-dependent effect was observed with amoxicillin regimens. The time of regrowth was significantly delayed when amoxicillin was combined with fosfomycin. By using a multivariate analysis, we demonstrated that the most important parameter correlated to efficacy of the combination amoxicillin-fosfomycin was the length of the period during which the concentration of amoxicillin remained above the MIC. We demonstrated that the in vivo efficacy of the combination of amoxicillin and fosfomycin gave higher antibacterial effect than each monotherapy.

[A case of toxic shock syndrome induced by MRSA after sinus surgery]

We present a case of toxic shock syndrome (TSS) induced by MRSA after sinus surgery. The patient was a 64-year-old woman who had undergone sinus surgery because of chronic sinusitis. Nine days after the surgery, she began to have sore throat, fever, and diffuse erythroderma followed by severe hypotension and renal dysfunction. Culture of sputum, nasal discharge and stool showed MRSA. Blood culture was negative. She was treated with intravenous fluids, catecholamines and antibiotics (vancomycin and fosfomycin). Continuous hemodiafiltration was started because of oliguria. Her condition improved gradually and she was discharged about a month after the onset of her illness. We should recognize that TSS can occur as a fatal complication after nasal surgery.

In vivo activity and pharmacodynamics of cefotaxime or ceftriaxone in combination with fosfomycin in fibrin clots infected with highly penicillin-resistant Streptococcus pneumoniae

Using a clinical pneumococcal strain for which MICs were 2, 0.5, 0.5, and 16 mg/liter for penicillin, cefotaxime, ceftriaxone, and fosfomycin, respectively, we studied the efficacies of these antibiotics alone and in combination in one or two doses or in continuous infusion over 6 h in the treatment of the prolonged (48-h) experimental fibrin clot infections in rabbits. Doses were chosen to obtain low antibiotic concentrations. We observed the highest bacterial reductions (change in log10 CFU per gram) with the following five regimens: combination of cefotaxime plus fosfomycin given in two divided doses 6 h apart (each at 50 mg/kg of body weight given intravenously (4.2 +/- 0.7 CFU/g), ceftriaxone (8 mg/kg given once intravenously) along with one or two doses of fosfomycin (3.79 +/- 0.6 and 3.95 +/- 0.5 CFU/g), cefotaxime alone administered in two divided doses (3.6 +/- 0.4 CFU/g), and a 6-h continuous infusion of cefotaxime (100 mg/kg) with fosfomycin (100 mg/kg) (3.5 +/- 0.4 CFU/g). The bacterial reductions obtained with these five regimens were all higher than those obtained with the other regimens tested (P < 0.05). The time of bacterial regrowth was significantly delayed with the two doses of the cefotaxime-fosfomycin regimens (23.2 +/- 11 h) compared with those with the other combinations (P < 0.05). The rate of bacterial regrowth with this regimen was even lower than that observed with cefotaxime alone given in two doses (P < 0.05). By a multivariate analysis, the most important independent parameters for efficacy were the maximal concentrations of beta-lactam antibiotics and the residual concentration of fosfomycin and, for the combinations, the log of the area under the concentration-time curve/MIC ratio for beta-lactam antibiotics. From these findings, the combinations cefotaxime or ceftriaxone plus fosfomycin could be proposed for the treatment of infections caused by highly penicillin-resistant pneumococci.

[A case report of pyomyositis--early diagnosis and follow-up by MRI]

We report a rare case of pyomyositis in a 28-year-old Japanese woman who was not immunocompromised. She was admitted because of high fever, sore throat, and severe tenderness and swelling of the right calf. Redness, swelling, and tenderness indicated presence of acute inflammation in the calf. CT of the lower extremities demonstrated low density areas in the right soleus muscle and surrounding fascia with marked swelling, which were of high signal on T2 weighted images of MRI. There was no finding of abscess formation. A tentative clinical diagnosis of acute pyomyositis was made, and antibiotics therapy with a combination of fosfomycin and sulbactam/cefoperazone was started although the arterial blood culture was negative for bacteria. Associated acute tonsilitis was the most probable focus of pyomyositis. Antibiotics relieved her symptoms, and the inflammation subsided in several weeks. No surgical procedure was necessary. MRI taken tree weeks after the onset demonstrated abscess formation between the soleus and gastrocnemius muscles. Slight high intensity indicating scar formation remained in the area of the former abscess six weeks after the onset. MRI was very useful not only in making the early diagnosis but also in the follow-up of pyomyositis.