One-Pot Biocatalytic Synthesis of Primary, Secondary, and Tertiary Amines with Two Stereocenters from α,β-Unsaturated Ketones Using Alkyl-Ammonium Formate

The efficient asymmetric catalytic synthesis of amines containing more than one stereogenic center is a current challenge. Here, we present a biocatalytic cascade that combines ene-reductases (EReds) with imine reductases/reductive aminases (IReds/RedAms) to enable the conversion of α,β-unsaturated ketones into primary, secondary, and tertiary amines containing two stereogenic centers in very high chemical purity (up to >99%), a diastereomeric ratio, and an enantiomeric ratio (up to >99.8:<0.2). Compared with previously reported strategies, our strategy could synthesize two, three, or even all four of the possible stereoisomers of the amine products while precluding the formation of side-products. Furthermore, ammonium or alkylammonium formate buffer could be used as the only additional reagent since it acted both as an amine donor and as a source of reducing equivalents. This was achieved through the implementation of an NADP-dependent formate dehydrogenase (FDH) for the in situ recycling of the NADPH coenzyme, thus leading to increased atom economy for this biocatalytic transformation. Finally, this dual-enzyme ERed/IRed cascade also exhibits a complementarity with the recently reported EneIRED enzymes for the synthesis of cyclic six-membered ring amines. The ERed/IRed method yielded trans-1,2 and cis-1,3 substituted cyclohexylamines in high optical purities, whereas the EneIRED method was reported to yield one cis-1,2 and one trans-1,3 enantiomer. As a proof of concept, when 3-methylcyclohex-2-en-1-one was converted into secondary and tertiary chiral amines with different amine donors, we could obtain all the four possible stereoisomer products. This result exemplifies the versatility of this method and its potential for future wider utilization in asymmetric synthesis by expanding the toolbox of currently available dehydrogenases via enzyme engineering and discovery.

High-Yield Synthesis of Enantiopure 1,2-Amino Alcohols from l-Phenylalanine via Linear and Divergent Enzymatic Cascades

Enantiomerically pure 1,2-amino alcohols are important compounds due to their biological activities and wide applications in chemical synthesis. In this work, we present two multienzyme pathways for the conversion of l-phenylalanine into either 2-phenylglycinol or phenylethanolamine in the enantiomerically pure form. Both pathways start with the two-pot sequential four-step conversion of l-phenylalanine into styrene via subsequent deamination, decarboxylation, enantioselective epoxidation, and enantioselective hydrolysis. For instance, after optimization, the multienzyme process could convert 507 mg of l-phenylalanine into (R)-1-phenyl-1,2-diol in an overall isolated yield of 75% and >99% ee. The opposite enantiomer, (S)-1-phenyl-1,2-diol, was also obtained in a 70% yield and 98–99% ee following the same approach. At this stage, two divergent routes were developed to convert the chiral diols into either 2-phenylglycinol or phenylethanolamine. The former route consisted of a one-pot concurrent interconnected two-step cascade in which the diol intermediate was oxidized to 2-hydroxy-acetophenone by an alcohol dehydrogenase and then aminated by a transaminase to give enantiomerically pure 2-phenylglycinol. Notably, the addition of an alanine dehydrogenase enabled the connection of the two steps and made the overall process redox-self-sufficient. Thus, (S)-phenylglycinol was isolated in an 81% yield and >99.4% ee starting from ca. 100 mg of the diol intermediate. The second route consisted of a one-pot concurrent two-step cascade in which the oxidative and reductive steps were not interconnected. In this case, the diol intermediate was oxidized to either (S)- or (R)-2-hydroxy-2-phenylacetaldehyde by an alcohol oxidase and then aminated by an amine dehydrogenase to give the enantiomerically pure phenylethanolamine. The addition of a formate dehydrogenase and sodium formate was required to provide the reducing equivalents for the reductive amination step. Thus, (R)-phenylethanolamine was isolated in a 92% yield and >99.9% ee starting from ca. 100 mg of the diol intermediate. In summary, l-phenylalanine was converted into enantiomerically pure 2-phenylglycinol and phenylethanolamine in overall yields of 61% and 69%, respectively. This work exemplifies how linear and divergent enzyme cascades can enable the synthesis of high-value chiral molecules such as amino alcohols from a renewable material such as l-phenylalanine with high atom economy and improved sustainability.

High Regio- and Stereoselective Multi-enzymatic Synthesis of All Phenylpropanolamine Stereoisomers from β-Methylstyrene

We present a one‐pot cascade for the synthesis of phenylpropanolamines (PPAs) in high optical purities (er and dr up to >99.5 %) and analytical yields (up to 95 %) by using 1‐phenylpropane‐1,2‐diols as key intermediates. This bioamination entails the combination of an alcohol dehydrogenase (ADH), an ω‐transaminase (ωTA) and an alanine dehydrogenase to create a redox‐neutral network, which harnesses the exquisite and complementary regio‐ and stereo‐selectivities of the selected ADHs and ωTAs. The requisite 1‐phenylpropane‐1,2‐diol intermediates were obtained from trans‐ or cis‐β‐methylstyrene by combining a styrene monooxygenase with epoxide hydrolases. Furthermore, in selected cases, the envisioned cascade enabled to obtain the structural isomer (1S,2R)‐1‐amino‐1‐phenylpropan‐2‐ol in high optical purity (er and dr >99.5 %). This is the first report on an enzymatic method that enables to obtain all of the four possible PPA stereoisomers in great enantio‐ and diastereo‐selectivity.

Regio- and stereoselective multi-enzymatic aminohydroxylation of β-methylstyrene using dioxygen, ammonia and formate

We report an enzymatic route for the formal regio- and stereoselective aminohydroxylation of β-methylstyrene that consumes only dioxygen, ammonia and formate; carbonate is the by-product. The biocascade entails highly selective epoxidation, hydrolysis and hydrogen-borrowing alcohol amination. Thus, β-methylstyrene was converted into 1R,2R and 1S,2R-phenylpropanolamine in 59-63% isolated yields, and up to >99.5: <0.5 dr and er.

Generation of amine dehydrogenases with increased catalytic performance and substrate scope from ε-deaminating L-Lysine dehydrogenase

Amine dehydrogenases (AmDHs) catalyse the conversion of ketones into enantiomerically pure amines at the sole expense of ammonia and hydride source. Guided by structural information from computational models, we create AmDHs that can convert pharmaceutically relevant aromatic ketones with conversions up to quantitative and perfect chemical and optical purities. These AmDHs are created from an unconventional enzyme scaffold that apparently does not operate any asymmetric transformation in its natural reaction. Additionally, the best variant (LE-AmDH-v1) displays a unique substrate-dependent switch of enantioselectivity, affording S- or R-configured amine products with up to >99.9% enantiomeric excess. These findings are explained by in silico studies. LE-AmDH-v1 is highly thermostable (Tm of 69 °C), retains almost entirely its catalytic activity upon incubation up to 50 °C for several days, and operates preferentially at 50 °C and pH 9.0. This study also demonstrates that product inhibition can be a critical factor in AmDH-catalysed reductive amination.

A Chimeric Styrene Monooxygenase with Increased Efficiency in Asymmetric Biocatalytic Epoxidation

The styrene monooxygenase (SMO) system from Pseudomonas sp. consists of two enzymes (StyA and StyB). StyB catalyses the reduction of FAD at the expense of NADH. After the transfer of FADH2 from StyB to StyA, reaction with O2 generates FAD-OOH, which is the epoxidising agent. The wastage of redox equivalents due to partial diffusive transfer of FADH2 , the insolubility of recombinant StyB and the impossibility of expressing StyA and StyB in a 1:1 molar ratio reduce the catalytic efficiency of the natural system. Herein we present a chimeric SMO (Fus-SMO) that was obtained by genetic fusion of StyA and StyB through a flexible linker. Thanks to a combination of: 1) balanced and improved expression levels of reductase and epoxidase units, and 2) intrinsically higher specific epoxidation activity of Fus-SMO in some cases, Escherichia coli cells expressing Fus-SMO possess about 50 % higher activity for the epoxidation of styrene derivatives than E. coli cells coexpressing StyA and StyB as discrete enzymes. The epoxidation activity of purified Fus-SMO was up to three times higher than that of the two-component StyA/StyB (1:1, molar ratio) system and up to 110 times higher than that of the natural fused SMO. Determination of coupling efficiency and study of the influence of O2 pressure were also performed. Finally, Fus-SMO and formate dehydrogenase were coexpressed in E. coli and applied as a self-sufficient biocatalytic system for epoxidation on greater than 500 mg scale.

Evaluation of new anti-infective drugs for the treatment of antibiotic-associated colitis. Infectious Diseases Society of America and the Food and Drug Administration

Colitis due to Clostridium difficile is diagnosed in 10%-15% of hospitalized patients who develop diarrhea after treatment with antimicrobial drugs. Diagnosis is based on the concurrence of diarrhea, one or more signs or symptoms of enteric intoxication, and stool from which toxigenic C. difficile is isolated or from which its toxins are identified. Clinical trials evaluating therapy may be placebo controlled (for mild disease) or concurrently controlled with an active drug. A randomized, double-blind study design is preferred. Outcome should be assessed by monitoring of the degree of inflammation of the bowel mucosa, the intensity and severity of diarrhea, the duration of illness, changes in stool form, and the eradication of C. difficile or its toxins from stool. Because C. difficile can be a component of the normal gastrointestinal flora, assessment of clinical outcome is paramount.

Evaluation of new anti-infective drugs for the treatment of acute infectious diarrhea. Infectious Diseases Society of America and the Food and Drug Administration

This guideline includes diarrhea causing infantile mortality in which a bacterial pathogen is recovered and for which oral rehydration therapy is an important component of care as well as traveler's diarrhea (with or without recovery of a pathogen). Diarrhea is defined as the passage of three or more unformed stools per day plus--in all patients except infants--one or more signs or symptoms of enteric infection. The preferred study design is prospective and randomized, with an active concurrent control and (when possible) blinding. Placebo-controlled trials may be performed if the severity of disease is judged by the investigator to be mild or moderate. It is desirable that both clinical and microbiological outcome be determined. Microbiological eradication is paramount.

Evaluation of new anti-infective drugs for the treatment of diarrhea caused by Cryptosporidium. Infectious Diseases Society of America and the Food and Drug Administration

Cryptosporidium is a coccidian protozoan that produces symptoms by infesting the small bowel. The illness is characterized by watery stools, anorexia, weight loss, and abdominal pain. Diagnosis is made by visualization of the organisms on microscopic examination of stool. There currently is no approved therapy for this infection. A randomized, double-blind, placebo-controlled study design is recommended. Stratification of patients by age and immune status should be considered. Two stool samples obtained 48 hours to 7 days after completion of therapy should be negative for Cryptosporidium oocysts. Assessment of microbiological outcome is paramount.

Evaluation of new anti-infective drugs for the treatment of typhoid fever. Infectious Diseases Society of America and the Food and Drug Administration

Typhoid fever is an acute febrile illness caused by Salmonella typhi. The evidence of blood-borne infection required for study entry includes clinical signs and symptoms plus confirmation of the presence of S. typhi in blood or other tissues or body fluids. The preferred study design is prospective and randomized with an active concurrent control. It is preferred that the investigator or an evaluator be blinded to therapy. In general, treatment should be administered for 2 weeks until it is demonstrated that a shorter course is as efficacious and as safe. Follow-up cultures of specimens from sites originally shown to be infected with S. typhi should be performed unless the diagnostic procedure places the patient at unnecessary risk.

Evaluation of new anti-infective drugs for the treatment of chronic carriage of Salmonella. Infectious Diseases Society of America and the Food and Drug Administration

The chronic carriage of salmonellae is defined as the shedding of a Salmonella species for > or = 1 year, as documented by an initial positive culture of a stool sample obtained at least 1 month after resolution of the acute illness and repeated positive cultures for at least 1 year. Clinical trials of investigational anti-infective drugs for the treatment of the salmonella carrier state may be conducted with a placebo control or an active concurrent control. A crossover design also may be employed for establishing efficacy. Patients should generally receive therapy for at least 6 weeks. Outcome will be assessed only by microbiological criteria. Determination of the interval required for the suppression of salmonellae and follow-up for 6 months after completion of therapy are recommended.

Evaluation of new anti-infective drugs for the treatment of diarrhea caused by Entamoeba histolytica. Infectious Diseases Society of America and the Food and Drug Administration

Entamoeba histolytica causes colonic infection that ranges from asymptomatic carriage to invasive disease with infection of extraintestinal organs, particularly the liver. The disease occurs in both sporadic and epidemic forms. Diagnosis requires visualization of trophozoites or cysts by microscopic examination of stool, colonic scrapings, or biopsy specimens. Patients with either asymptomatic or symptomatic disease may be eligible for clinical trials. A prospective, randomized, double-blind, placebo-controlled study design is recommended for asymptomatic carriers and an active-concurrent-control study design for symptomatic patients. Final outcome should be assessed 48 hours to 7 days after completion of therapy. Assessment of microbiological outcome is paramount.

Evaluation of new anti-infective drugs for the treatment of gastritis and peptic ulcer disease associated with infection by Helicobacter pylori. Infectious Diseases Society of America and the Food and Drug Administration

Helicobacter pylori is a gram-negative, microaerophilic, spiral bacillus. Infection by this organism is currently believed to be the major cause of type B gastritis. Inflammation and infection may persist for years in the absence of therapeutic intervention. There is currently no approved antimicrobial therapy for gastritis. Clinical investigations have shown that combination regimens including bismuth salts and antimicrobial drugs result in the relief of symptoms, the resolution of histologic evidence of gastritis, the eradication of H. pylori, high rates of ulcer healing, and lower rates of ulcer relapse than have been found with other therapies (antacids and H2 antagonists). A randomized, double-blind, placebo-controlled study design is recommended for evaluation of new therapies. Study participants should have their progress monitored by endoscopy performed at enrollment, at completion of therapy, and 3 months thereafter. Assessment of microbiological outcome is paramount for final evaluation of the patient.

Evaluation of new anti-infective drugs for the treatment of cholera. Infectious Diseases Society of America and the Food and Drug Administration

Cholera is an acute gastrointestinal infection caused by Vibrio cholerae. It is characterized by watery diarrhea that may lead to massive fluid loss, which in turn may result in hypotension, shock, and death within hours. Key to the treatment of cholera is fluid replacement. Anti-infective therapy decreases the severity and duration of diarrhea and the duration of shedding of V. cholerae. Enrolled patients should have diarrhea that is moderate to severe and a culture that ultimately yields V. cholerae. A prospective, randomized, active-controlled clinical trial is preferred. Studies should be double-blinded or evaluator-blinded. The rapidity with which the organism is eliminated from stool may be assessed. Both clinical and microbiological outcome should be determined. Assessment of microbiological eradication is paramount, since fluid replacement may suffice for treatment of signs and symptoms.

Evaluation of new anti-infective drugs for the treatment of diarrhea caused by Giardia lamblia. Infectious Diseases Society of America and the Food and Drug Administration

Giardia lamblia is a flagellate protozoan that produces symptoms by infecting the small bowel and biliary tract in the trophozoite form. Diagnosis is currently established by microscopic visualization of the organism in appropriate intestinal contents (stool, small-bowel contents, or biopsy specimen). Adult patients with diarrhea and one or more enteric symptoms may be enrolled in clinical trials of new drugs for the treatment of giardial disease. A randomized, double-blind, active-concurrent-control design is recommended. Post hoc stratification by age, immune status, chronicity of disease, and ease of establishing diagnosis (organism load) may be performed. Microbiological assessment 48 hours to 7 days after the completion of therapy is paramount for determining final outcome.

The clinical experience with ofloxacin in the treatment of sexually transmitted diseases

Sexually transmitted diseases are an important cause of morbidity in women. Some of the common causes of sexually transmitted disease include Neisseria gonorrhoeae, Chlamydia trachomatis, and in some patients Ureaplasma urealyticum. N. gonorrhoeae has become more resistant to traditional therapies including penicillin. Resistance to penicillin is mediated by the elaboration of beta-lactamase for most organisms and by chromosomal resistance in others. Resistance to tetracycline and spectinomycin has been clearly identified, as has an increase in the minimum inhibitory concentrations to some cephalosporins. Because of the potential for concomitant infection with N. gonorrhoeae and C. trachomatis, many patients are currently treated with a combination of a single dose of ceftriaxone plus a tetracycline for 7 days. Therefore it is significant that a single agent, ofloxacin, has been introduced recently for the treatment of such mixed infections. It also has the potential for treating N. gonorrhoeae resistant to other drugs.

Worldwide clinical experience with ofloxacin in urologic cases

Ofloxacin is a quinolone carboxylic acid with a broad spectrum of activity for gram-negative pathogens that are common causes of urologic infections including cystitis, pyelonephritis, and prostatitis. The data in this publication will review clinical trials in urologic infections as well as the literature which dates from January 1983 through February 1989. The database includes over four hundred reports from nineteen foreign countries and involves data from more than 21,000 patients. The data from the United States were accumulated in clinical trials conducted between 1984 and 1988. Ofloxacin has certain attributes that make it a potentially useful drug in the treatment of urologic infections. These include the high bioavailability from oral administration and the fact that the product is excreted almost entirely by the kidney, primarily as the active parent compound. Urinary levels of ofloxacin two to four hours postadministration can achieve concentrations above 600 micrograms/mL after a single 400-mg dose. Urinary levels twenty-four hours after a single dose are noted to be typically around 50 micrograms/mL. Both of these concentrations are well above the minimum inhibitory concentration (MIC90) for uropathogens, which might be below 1 microgram/mL for many uropathogens. With respect to the prostate, ofloxacin penetrates prostatic tissues well and can achieve concentrations of approximately 4.5 micrograms per gram of prostate tissue as a mean peak level. Prostate levels ten hours postdose will typically be approximately 2.7 micrograms per gram of prostatic tissue. These levels exceed the MIC90 for the majority of prostatic pathogens as well.

Review of the efficacy of oral norfloxacin in pyelonephritis and nosocomial urinary tract infection

One hundred thirty-eight patients with pyelonephritis were treated with norfloxacin, 400 mg twice daily. Women accounted for 74% of cases, and Escherichia coli was the predominant pathogen, accounting for 51% of organisms. Tests for antibody-coated bacteria (ACB) were performed in 48% of patients, and 72% (48 of 67) were positive. Forty percent of the patients had temperatures greater than 37.6 degrees C at the time of study entry. Patients who had both fevers and positive ACB tests had cure rates similar to those of afebrile, ACB-negative patients. Norfloxacin was also highly effective in the treatment of multiply resistant, nosocomial urinary tract infections (UTIs), in which Pseudomonas aeruginosa and E. coli predominated. It is concluded that, when used appropriately, i.e., in nonbacteremic patients who are able to absorb oral drugs, norfloxacin is a highly effective alternative modality in the therapy of certain UTIs that historically have been treated with parenteral antibiotics.

Norfloxacin versus trimethoprim-sulfamethoxazole in the treatment of urinary tract infections

In a controlled, randomized trial of 133 patients with proven urinary tract infections (UTIs), significantly more pathogens were found to be susceptible to norfloxacin than to trimethoprim-sulfamethoxazole (TMP-SMZ) (p less than 0.01). Among patients with pathogens susceptible to both drugs, more of those treated with norfloxacin were cured or improved (p = 0.06). When at least one patient variable, i.e., prior history of therapy, was corrected for, this difference became significant (p = 0.03). Norfloxacin eradicated 11 of 13 infections due to Pseudomonas aeruginosa and 6 of 7 due to enterococci. Five patients treated with norfloxacin and two treated with TMP-SMZ had relapses within 6 weeks. Significantly fewer adverse experiences occurred in patients receiving norfloxacin (p less than 0.01).

Treatment of urinary tract infection with norfloxacin. Analysis of cost

Twenty-five patients with urinary tract infection were treated with norfloxacin, a fluoroquinolone antibacterial with a wide spectrum of activity for an oral agent. Of 22 patients who were evaluable, 20 had complicated urinary tract infection; infection was cured in 19 patients at one week after treatment. Optimal alternative treatments were also selected in norfloxacin's stead, based on each patient's characteristics and the results of susceptibility testing for each isolated pathogen. Direct costs for alternative treatment ranged from $7 to $970. The results indicated that for those patients with suspected or proven urinary tract infection caused by multiresistant bacteria, therapy with norfloxacin may represent a cost-effective choice.

Use of norfloxacin in the treatment of acute diarrheal disease

In studies conducted in seven countries, 392 persons with acute diarrhea were enrolled and randomly assigned to one of three regimens. In order to compare the effectiveness of various therapies for acute gastroenteritis, patients were treated for five days with either norfloxacin, 400 mg twice daily, norfloxacin, 400 mg three times a day, or trimethoprim/sulfamethoxazole, (160 mg/800 mg) twice daily. Clinical cure occurred in 89 percent (lower dose) and 91 percent (higher dose) of those treated with norfloxacin, compared with 78 percent of those receiving trimethoprim/sulfamethoxazole; cure rates in each treatment group were greater when the patient's stool contained fecal leukocytes. In 105 of 106 (99 percent) patients treated with either dose of norfloxacin and in 49 of 52 (94 percent) trimethoprim/sulfamethoxazole-treated subjects, the bacterial enteropathogen identified in the pretreatment stool was eradicated on the posttreatment specimen. Two percent (two patients) of those receiving the lower dose of norfloxacin, 3 percent (two patients) of those receiving trimethoprim/sulfamethoxazole, and 4 percent (three patients) of those receiving the higher dose of norfloxacin experienced minor and transient adverse hematologic or blood chemistry reactions. In addition, mild cutaneous reactions that were attributed to the study medications developed in two patients receiving the higher dose of norfloxacin and in three patients who received trimethoprim/sulfamethoxazole. These studies indicate that norfloxacin is safe and effective therapy for bacterial diarrhea.

Effect of inoculum size on in vitro activity of norfloxacin against fecal anaerobic bacteria. Rationale for selective decontamination of the digestive tract

Previous studies have shown that anaerobic bacteria are susceptible to norfloxacin at the levels attained in the feces. Conversely, studies in laboratory animals and neutropenic humans using norfloxacin for selective decontamination of the digestive tract have shown that norfloxacin markedly reduces the aerobic enteric flora without reducing fecal anaerobic flora. In an effort to resolve this paradox, the effect of a 10(9) colony-forming units (cfu)/ml inoculum, which is more reflective of actual fecal counts than the standard 10(5) cfu/ml inoculum, on the activity of norfloxacin against two fecal Escherichia coli isolates and 16 fecal anaerobic isolates was studied. The results showed a marked inoculum effect at 10(9) cfu/ml for most anaerobic isolates but not for the E. coli strains tested. At 256 micrograms/ml, all E. coli were killed while the anaerobic bacteria maintained colony counts greater than or equal to 10(9) cfu/ml. Hence, the lack of anaerobic activity (minimal inhibitory concentration greater than or equal to 512 micrograms/ml) at higher fecal inocula might explain the utility of norfloxacin in selective decontamination of the bowel.

Norfloxacin: review of safety studies

The tolerability profile of norfloxacin, the first of a new generation of fluoroquinolone carboxylic acid antibacterials, has been defined in numerous laboratory animal and human trials. Whether administered for moderate or protracted periods, norfloxacin has been relatively safe in animals over a wide range of doses. There has been no evidence of a teratogenic effect in any of the animal species tested (rat, rabbit, mouse, monkey) at six to 50 times the human dose (400 mg twice daily). However, norfloxacin has been shown to produce embryonic loss in monkeys when given in doses 10 times the maximal human dose, resulting in peak plasma levels that are two to three times those obtained in humans. Although there are no adequate and well-controlled studies in pregnant women, norfloxacin is not recommended for use in this population because it, like other drugs in this class, causes arthropathy in immature animals. In animals, norfloxacin is neither mutagenic nor carcinogenic, and, in clinical trials, norfloxacin-related adverse experiences have been uncommon. Those that have occurred have been generally mild, requiring discontinuation of therapy in less than 1 percent of patients. The most frequently reported side effects have been nausea, dyspepsia, headache, and dizziness. Administration of 400 mg of norfloxacin at two or three times a day has been associated with reasonably good gastrointestinal tolerance.

Compassionate use of norfloxacin

Norfloxacin, a new oral fluoroquinolone, has a spectrum of activity and pharmacology that suggest it may be useful in certain infections in which other agents are inactive or have anticipated toxicity. This report is an analysis of 61 "compassionate" requests for norfloxacin that resulted in 42 treatment courses. The reasons for use included multiresistant pathogens susceptible only to norfloxacin in 42 percent, failure of prior use of a marketed antibiotic in 34 percent, and preferred use of norfloxacin due to anticipated toxicity from an aminoglycoside in 32 percent or from other agents in 9 percent. Infections treated included 29 complicated urinary tract infections, 23 involving multiresistant Pseudomonas species, and 10 gastrointestinal infections, seven involving Salmonella species. Prophylaxis of infection was initiated in three neutropenic patients with leukemia. The duration of norfloxacin therapy ranged from eight to 28 days at a daily dose of 800 mg (400 mg twice daily). Norfloxacin treatment resulted in clinical cure or improvement in 84 percent of patients and eradicated the etiologic pathogen(s) 52 percent of the time. In Pseudomonas species infections, cure was achieved in 29 percent of patients and 57 percent showed improvement; the pathogen was eradicated in 43 percent of these infections. Resistance developed in four of the eight Pseudomonas species infections that persisted. Based on a review of compassionate therapy cases, it appears that norfloxacin is effective oral therapy for many complicated urinary and gastrointestinal infections for which other agents cannot be used because of bacterial resistance or anticipated toxicity.

Norfloxacin in the treatment of urinary tract infections in men with and without identifiable urologic complications

A retrospective analysis of data from the treatment of 95 men with nonbacteremic urinary tract infections (UTIs) (clean-catch urinary bacterial count greater than or equal to 10(5) colony-forming units/ml) who received norfloxacin (400 mg orally twice daily) was performed. Treatment duration ranged from a required minimum of seven days to a maximum of 30 days. If an underlying anatomic or functional condition existed that might decrease the likelihood of a favorable medical response and/or require prolonged treatment, the patient's UTI was considered "complicated." In addition to eight patients with polymicrobic UTIs (usually involving enterococci or Pseudomonas aeruginosa), 48 men (i.e., 51 percent of the total population) had an identifiable complication. Complications included benign prostatic hypertrophy in 13 patients; prostatic cancer in four; urethral stricture in four; quadriplegia/paraplegia with indwelling urinary catheter in four; prostatism in three; and other conditions commonly recognized as altering the response to antibiotic treatment. Among the 95 patients treated, 76 (80 percent) were considered to have had a cure and five (5 percent) showed improvement. Fourteen patients (15 percent) failed to show a response to treatment. Of the 48 patients with UTI and defined complications, 36 (75 percent) had a cure, three (6 percent) showed improvement, and therapy failed in nine (19 percent). Ninety-seven percent (105 of 108) of the pretreatment bacterial isolates were susceptible to norfloxacin. In addition to the three resistant organisms that were present prior to therapy, three organisms (two P. aeruginosa and one Enterobacter) persisted and acquired resistance during therapy. Five adverse clinical experiences and six adverse laboratory experiences were noted. Only one of the former (mild heartburn) was thought to be drug related, and no adverse experience was considered serious or required discontinuation of treatment. Gastrointestinal tolerability of oral norfloxacin was good.

Safety and efficacy of imipenem/cilastatin in treatment of complicated urinary tract infections

Forty-three patients were treated with imipenem/cilastatin for urinary tract infections. The patients were predominantly men (77 percent), 60 years of age or older (81 percent), and had infections caused by Pseudomonas aeruginosa (58 percent). Forty of 43 cases were complicated (including tumor, stone, obstruction, and renal insufficiency). Approximately 33 percent of patients were febrile (temperature greater than 100.4 degrees). All patients received 500 mg of imipenem/cilastatin intravenously every eight hours. Microbiologic eradication was defined as a sterile urine culture sample obtained from two consecutive urine cultures, one during therapy and one five to nine days after therapy. All patients experienced clinical improvement with microbiologic eradication. No patients experienced drug-related clinical adverse effects.

Pulmonary cryptococcosis and Cushing's syndrome

Pulmonary cryptococcosis occurred in two patients with Cushing's syndrome, both of whom were successfully treated with amphotericin B and flucytosine. Excessive endogenous production of corticosteroids may have predisposed these patients to the development of opportunistic infection. Persons with Cushing's syndrome and a pulmonary infiltrate should be examined for infection with Cryptococcus neoformans in addition to an examination for ectopic adrenocorticotropic hormone production.

The comparative activity of norfloxacin with other antimicrobial agents against Gram-positive and Gram-negative bacteria

Norfloxacin (MK0366) displayed appreciable activity against the great majority of Gram-negative and Gram-positive bacteria. The minimum inhibitory concentration for 90% of isolates (MIC90) of the Enterobacteriaceae was 0.5 mg/l or less while for Campylobacter, Neisseria, Haemophilus MIC90s were 0.25 mg/l or less. Norfloxacin was also among the most active drugs tested against methicillin susceptible and resistant Staphylococcus aureus, Staph. epidermidis, enterococci and Pseudomonas aeruginosa with MIC90s between 0.5 and 4 mg/l.

Treatment of gram-negative bacillary meningitis: role of the new cephalosporin antibiotics

Results of the treatment of gram-negative bacillary meningitis have been disappointing: mortality is extremely high, and treatment with chloramphenicol has shown a high failure rate. This failure rate for chloramphenicol is consistent with the wide gap between minimal inhibitory concentration and minimal bactericidal concentration of this drug for Escherichia coli, Klebsiella, and other Enterobacteriaceae. Cefotaxime, a new cephalosporin, is cidal for most gram-negative bacteria at concentrations of less than 0.25 microgram/ml. By late 1981, 137 patients with meningitis due to a variety of bacteria had been treated with this agent. Bacteriologic cure rates were 93% for meningitis due to Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae and 88% for meningitis due to gram-negative bacteria (94.4% for meningitis due to E. coli and Klebsiella). This new antibiotic shows considerable promise in the treatment of these forms of meningitis.

Comparative susceptibility of Yersinia enterocolitica, Eikenella corrodens, and penicillin-resistant and penicillin-susceptible Streptococcus pneumoniae to beta-lactam and alternative antimicrobial agents

The antimicrobial susceptibilities were determined for 14 strains of Yersinia enterocolitica, 28 strains of Eikenella corrodens, 10 strains of penicillin-resistant Streptococcus pneumoniae, and 10 strains of penicillin-susceptible S. pneumoniae. Y. enterocolitica was found to be susceptible to the aminoglycosides tested and to chloramphenicol, moxalactam, cefoperazone, and cefotaxime but resistant to ampicillin and variably susceptible to carbenicillin, cefoxitin, and cefazolin. On a weight basis, cefotaxime and moxalactam were the most active agents against E. corrodens. Most strains of E. corrodens were resistant to the aminoglycosides tested: gentamicin, tobramycin, kanamycin, and amikacin. Penicillin-resistant S. pneumoniae was most susceptible to cefotaxime and moxalactam. Cefotaxime was consistently active against all tested strains of Y. enterocolitica, E. corrodens, and penicillin-resistant S. pneumoniae, three unusual but clinically significant pathogens.

Designing appropriate therapy in the treatment of gram-negative bacillary meningitis

Gram-negative bacillary meningitis is being diagnosed more frequently, and the introduction of newer beta-lactam antibiotics has contributed significantly to successful therapy. These new agents--became of their ease of administration and relative safety--also allow nonspecialists to treat the disease. There are, however, pitfalls in therapy of infections due to this heterogenous group of organisms. Extremely susceptible organisms, such as Escherichia coli and Klebsiella pneumoniae, most often respond to cephalosporin monotherapy, whereas relatively resistant organisms such as Acinetobacter and some Enterobacter may not. In these cases, combination therapy with an aminoglycoside is warranted. Testing the infecting organism for antibiotic susceptibility at the appropriate inoculum and pH may be useful in predicting therapeutic outcome.

Susceptibility of dermatiaceous fungi to amphotericin B, miconazole, ketoconazole, flucytosine and rifampin alone and in combination

The dematiaceous fungi comprise a group of organisms that are deeply pigmented and found in soil or on decaying organic material, such as wood. The majority of infections with these fungi presumably results from traumatic inoculation. Although various forms of infection have been appreciated for some time, none of the presently available antifungal drugs have been shown to have predictable activity against these organisms. We report on the activity in vitro of various antifungal agents alone and in combination against various dematiaceous fungi.

Chronic mycotic meningitis with spinal involvement (arachnoiditis): a report of five cases

Five patients developed mycotic spinal arachnoiditis-meningitis causing signs and symptoms of spinal cord neoplasm. Four had cryptococcal infection, the fifth had aspergillosis. In three patients, diagnosis was made at surgery; all three developed acute fungal meningitis postoperatively and two died. The diagnosis was made nonsurgically in two patients and was followed by medical cure. These five and twelve other reported patients with mycotic spinal arachnoiditis shared features that suggested the diagnosis. In contrast to most patients with spinal tumors, those reported here tended to be young (mean age, 32 years), to lack evidence for a primary tumor, and to have a fluctuating history of spinal symptoms for several months. Frequent associated findings were recent pregnancy; the abuse of alcohol, narcotics, or both; and the presence of headache and fever. Plain roentgenograms of the spine were normal. No single finding was diagnostic, but the combination of several would be rare with spinal tumor.

Gram-negative bacillary meningitis. New therapy and changing concepts

Because the CSF is deficient in opsonic and phagocytic activity, optimal therapy for meningitis mandates the use of antibiotics that are bactericidal at achievable CSF concentrations. This therapeutic principles is satisfied for the common meningeal pathogens (Streptococcus pneumoniae, Haemophilus influenzae, Neisseria meningitidis) but is not readily achieved for the pathogens causing Gram-negative bacillary meningitis (GNBM), such as Klebsiella and Escherichia coli. The antibiotics used to treat GNBM, chloramphenicol and aminoglycosides, are not bactericidal against enteric pathogens at achievable CSF levels. Two new beta-lactam antibiotics, moxalactam disodium and cefotaxime sodium, are suitable agents for the treatment of GNBM. These antibiotics possess potent bactericidal activity against most enteric pathogens and achieve high levels in the CSF (15 to 35 micrograms/mL for moxalactam disodium and 2 to 10 micrograms/mL for cefotaxime sodium). Recent clinical studies document an 85% cure rate when these agents are used to treat GNBM.

Mycobacterium thermoresistibile: a new pathogen for humans

The first evidence of the potential pathogenicity of Mycobacterium thermoresistibile is presented. This mycobacterium, initially identified as Mycobacterium gordonae, was isolated repeatedly from sputum, a bronchoscopy specimen. and later, an open lung biopsy. The distinctive characteristics are described, including the unique ability of the organism to grow at 52 degrees C.

Susceptibility of gram-positive cocci to various antibiotics, including cefotaxime, moxalactam, and N-formimidoyl thienamycin

The activities of cefotaxime, moxalactam, MK 0787 (N-formimidoyl thienamycin), ampicillin, oxacillin, vancomycin, and clindamycin were compared against gram-positive cocci. MK 0787 was the most active and moxalactam was the least active of these drugs, except against methicillin-resistant Staphylococcus aureus, where vancomycin was most active, and penicillin-resistant pneumococci, where cefotaxime was more active.

Past and current roles for cephalosporin antibiotics in treatment of meningitis. Emphasis on use in gram-negative bacillary meningitis

The therapy of gram-negative bacillary meningitis is less than adequate to date; the agents recommended do not achieve bactericidal levels in purulent cerebrospinal fluid. Because optimal antibiotic therapy of meningitis occurs when the cerebrospinal fluid level of an antibiotic is above the concentration needed to kill the offending pathogen, another group of agents needs to be considered. The newer cephalosporins or cehalosporin-type antibiotics (cefotaxime, moxalactam), by virtue of their marked activity against gram-negative bacilli and their ability to achieve significant CSF levels, merit serious consideration as therapy for gram-negative bacillary meningitis. Investigators in Europe and the United States have developed preliminary data demonstrating the efficacy of these agents in a growing number of cases. In the group presented herein, of the 35 cases in which gram-negative bacillary meningitis was treated with the newer cephalosporins, there were only four failures.

Vancomycin and rifampin therapy for Staphylococcus epidermidis meningitis associated with CSF shunts: report of three cases

Three patients with Staphylococcus epidermis meningitis associated with cerebrospinal fluid (CSF) shunt devices were treated with a combination of intravenous vancomycin and oral rifampin. Two of the isolates were methicillin-resistant. All patients had a favorable clinical response. Time-kill curves showed that the addition of rifampin to vancomycin resulted in enhanced bactericidal activity against all isolates when compared to either antibiotic alone. This finding suggests that the combination of oral rifampin and intravenous vancomycin may be useful in the treatment of methicillin-resistant and recalcitrant methicillin-sensitive S. epidermis meningitis associated with CSF shunts. In vitro susceptibility testing should be performed.

Group B streptococcal pharyngitis in the compromised adult: therapeutic considerations

Group B streptococci (GBS) have been infrequently recognized as a cause of pharyngitis. We report three cases of GBS pharyngitis in patients with underlying diseases, two of whom were treated with and responded incompletely to oral beta-lactam antibiotics. The susceptibility of 20 clinical isolates of GBS was tested by a broth dilution method to six antibiotics which could conceivably be used in the therapy of GBS pharyngitis. Penicillin G, clindamycin, and erythromycin were most active with mean minimal inhibitory concentrations (MIC) of 0.06 μg/ml or less. Rifampin and cefaclor were least active with mean MICs of 0.71 ug/ml or more. Ampicillin was intermediate in its activity. Therapy traditionally used for Group A streptococcal (GAS) pharyngitis may, at times, be suboptimal for GBS pharyngitis in compromised patients. This may be due to higher minimal bactericidal concentrations (MBC) of GBS than GAS, to inadequate penetration of penicillins into pharyngeal tissues or to host factors. It is suggested that GBS can cause pharyngitis in adults, particularly the compromised patient, and that in cases where there is a poor response to penicillin or ampicillin therapy, alternative drugs (erythromycin or clindamycin) may be used.

Blunt trauma and liver abscess

Three cases of pyogenic liver abscess following blunt trauma to the torso are described. The association between blunt trauma with liver contusion and the development of bacterial pyogenic liver abscess is explored. Reported series of liver abscess are reviewed. It is suggested that physicians look for the development of liver abscess in patients who have had major blunt trauma to the torso. Physicians should also inquire about blunt trauma in patients with documented pyogenic liver abscesses.

Activity of moxalactam and cefotaxime alone and in combination with ampicillin or penicillin against group B streptococci

The activities of moxalactam and cefotaxime, alone and combined with ampicillin or penicillin, against 40 isolates of group B streptococci were assessed by using the microtiter broth dilution, checkerboard, and time-kill techniques. Penicillin and cefotaxime were bactericidal for all isolates at concentrations of 0.06 micrograms/ml or less. Ampicillin was slightly less active. Moxalactam was bactericidal for all strains at concentrations of 4 to 8 micrograms/ml. The ampicillin- moxalactam combination was partially synergistic for 60% of the isolates tested; the ampicillin-cefotaxime combination was partially synergistic for 35% of these isolates. No instances of antagonism were observed. In time-kill evaluations, ampicillin (3.0 micrograms/ml) and penicillin (0.75 micrograms/ml) effected 2.5 to 3.5 log10 reductions in numbers of colony-forming units. The addition of 4 micrograms of cefotaxime per ml or 8 to 16 micrograms of moxalactam per ml to penicillin or ampicillin did not alter killing kinetics. Moxalactam and cefotaxime neither enhanced nor decreased the activity of ampicillin or penicillin against group B streptococci.

Infections caused by Actinomyces viscosus

Two cases of Actinomyces viscosus infection of the lungs were seen in nonimmunosuppressed patients. One patient had a peripheral actinomycotic lung mass resembling a tumor. Both patients responded to a long course of penicillin therapy. Reports of A. viscosus infections are rare, although the organism colonizes the mouths of most adult humans. Only ten cases have previously been described. There is no characteristic of A. viscosus infection that can distinguish it from Actinomyces israelii or Actinomyces bovis infections. The illness usually manifests as a chronic disease weeks to months before the diagnosis, which can only be made by identification of the organism from a clinical specimen uncontaminated by sputum or mouth flora. Ignorance of the biochemical reactions and growth characteristics of this organism have in the past hindered its isolation and identification. At least three weeks of antibiotic therapy using agents to which A. viscosus is sensitive in vitro are required for cure.

Influence of inoculum size on activity of cefoperazone, cefotaxime, moxalactam, piperacillin, and N-formimidoyl thienamycin (MK0787) against Pseudomonas aeruginosa

Forty clinical isolates of Pseudomonas aeruginosa were tested for their susceptibility to cefoperazone, cefotaxime, moxalactam, piperacillin, N-formimidoyl thienamycin (MK0787), and gentamicin at three different inocula. At an inoculum of 5 x 10(3) colony-forming units (CFU) per ml, the minimum inhibitory concentrations (in micrograms per milliliter) for 90% of isolates (MIC90) were as follows: gentamicin, 1; N-formimidoyl thienamycin, 2; cefoperazone, 4; piperacillin, 8; moxalactam, 16; and cefotaxime, 16. When the inoculum was increased to 5 x 10(5) CFU/ml, the MIC90 for all drugs tested increased. Among the beta-lactam antibiotics, N-formimidoyl thienamycin and cefoperazone had the lowest MIC90 (8 micrograms/ml) at this inoculum. When the inoculum was increased further to 5 x 10(7) CFU/ml, an MIC90 could be determined only for gentamicin and N-formimidoyl thienamycin (4 and 8 micrograms/ml, respectively). Indeed, the MIC50 for moxalactam, cefotaxime, cefoperazone, and piperacillin was 128 micrograms/ml or more at this inoculum. The minimum bactericidal concentration for 90% of isolates (MBC90) at an inoculum of 5 x 10(5) CFU/ml ranged from 8 micrograms/ml for gentamicin and N-formimidoyl thienamycin to 128 micrograms/ml for cefotaxime. At the highest inoculum, however, whereas the MBC90 for gentamicin and N-formimidoyl thienamycin remained at 8 micrograms/ml, the MBC90 for each of the other drugs was greater than 128 micrograms/ml. N-Formimidoyl thienamycin was the only drug tested for which an MIC100 and MBC100 (MIC and MBC for 100% of isolates) could be determined, and these were not significantly different from the MIC90 and MCB90.