bluuebunny/crossref_metadata_2025 huggingface dataset:
Pharmacodynamics of (−)-β-2′,3′-Dideoxy-3′-Thiacytidine in Chronically Virus-Infected Woodchucks Compared to Its Pharmacodynamics in Humans
Authors: Hurwitz Selwyn J. , Tennant Bud C. , Korba Brent E. , Gerin John L. , Schinazi Raymond F.
Published: October 2018

The pharmacodynamics of (−)-β-2′,3′-dideoxy-3′-thiacytidine (3TC) was studied in chronically woodchuck hepatitis virus-infected woodchucks and compared to that in previous studies in hepatitis B virus (HBV)-infected humans. Net depletion rates of serum virus DNA in woodchucks receiving 3TC were modeled as a sum of an exponentially declining virus input and a first-order elimination. Preceding shoulders and pseudo-first-order virus half-lives in serum ranged from 1 to 7 days and were dose dependent. Higher plasma 3TC concentrations were needed in woodchucks for virus depletion similar to that attained in humans. Human HBV depletion curves from a previous clinical study with 3TC (≥100 mg per day) were described by a biexponential relationship. The average half-life value in humans, normalized to fraction of area under the serum virus load-time curve, was similar to the average half-life value observed in woodchucks given the highest 3TC dose (2.4 and 2.0 days, respectively). On cessation of therapy, virus load rebounds in woodchucks were dose dependent and resembled posttherapy virus “flares” reported to occur in humans. The estimates of drug exposures that could lead to optimal antiviral effects presented indicate that 3TC should not be underdosed and compliance should be monitored. The study of chronically infected woodchucks may prove useful for optimizing drug regimens for hepadnavirus infections.
Effects of Subinhibitory Concentrations of Antibiotics on Alpha-Toxin (
hla
) Gene Expression of Methicillin-Sensitive and Methicillin-Resistant
Staphylococcus aureus
Isolates
Authors: Ohlsen Knut , Ziebuhr Wilma , Koller Klaus-Peter , Hell Wolfgang , Wichelhaus Thomas A. , Hacker Jörg
Published: October 2018

Concentrations of antibiotics below the MIC are able to modulate the expression of virulence-associated genes. In this study, the influence of subinhibitory doses of 31 antibiotics on the expression of the gene encoding the staphylococcal alpha-toxin (
hla
), a major virulence factor of
Staphylococcus aureus
, was investigated with a novel gene fusion protocol. The most striking observation was a strong induction of
hla
expression by subinhibitory concentrations of β-lactams and an almost complete inhibition of alpha-toxin expression by clindamycin. Whereas glycopeptide antibiotics had no effect, the macrolide erythromycin and several aminoglycosides reduced and fluoroquinolones slightly stimulated
hla
expression. Furthermore, Northern blot analysis of
hla
mRNA and Western blot (immunoblot) analysis of culture supernatants of both methicillin-sensitive and methicillin-resistant
S. aureus
strains revealed that methicillin-induced alpha-toxin expression is a common phenomenon of alpha-toxin-producing strains. Some methicillin-resistant
S. aureus
isolates produced up to 30-fold more alpha-toxin in the presence of 10 μg of methicillin per ml than in its absence. The results indicate that the novel gene fusion technique is a useful tool for studying the modulation of virulence gene expression by antibiotics. Moreover, the results suggest that the effects of certain antibiotics on virulence properties may be relevant for the management of
S. aureus
infections.
Suppression of Murine Endotoxin Response by E5531, a Novel Synthetic Lipid A Antagonist
Authors: Kobayashi Seiichi , Kawata Tsutomu , Kimura Akifumi , Miyamoto Kaname , Katayama Koichi , Yamatsu Isao , Rossignol Daniel P. , Christ William J. , Kishi Yoshito
Published: October 2018

As a consequence of blood-borne bacterial sepsis, endotoxin or lipopolysaccharide (LPS) from the cell walls of gram-negative bacteria can trigger an acute inflammatory response, leading to a series of pathological events and often resulting in death. To block this inflammatory response to endotoxin, a novel lipid A analogue, E5531, was designed and synthesized as an LPS antagonist, and its biological properties were examined in vitro and in vivo. In murine peritoneal macrophages, E5531 inhibited the release of tumor necrosis factor alpha (TNF-α) byEscherichia coliLPS with a 50% inhibitory concentration (IC50) of 2.2 nM, while E5531 elicited no significant increases in TNF-α on its own. In support of a mechanism consistent with antagonism of binding to a cell surface receptor for LPS, E5531 inhibited equilibrium binding of radioiodinated LPS ([125I]2-(r-azidosalicylamido)-1, 3′-dithiopropionate-LPS) to mouse macrophages with an IC50of 0.50 μM. E5531 inhibited LPS-induced increases in TNF-α in vivo when it was coinjected with LPS into C57BL/6 mice primed withMycobacterium bovisbacillus Calmette-Guérin (BCG). In this model, the efficacy of E5531 was inversely correlated to the LPS challenge dose, consistent with a competitive antagonist-like mechanism of action. Blockade of the inflammatory response by E5531 could further be demonstrated in other in vivo models: E5531 protected BCG-primed mice from LPS-induced lethality in a dose-dependent manner and suppressed LPS-induced hepatic injury inPropionibacterium acnes-primed or galactosamine-sensitized mice. These results argue that the novel synthetic lipid A analogue E5531 can antagonize the action of LPS in in vitro and suppress the pathological effects of LPS in vivo in mice.
In Vitro and In Vivo Activities of Trybizine Hydrochloride against Various Pathogenic Trypanosome Species
Authors: Kaminsky Ronald , Brun Reto
Published: October 2018

Trybizine hydrochloride [O,O′-bis(4,6-diamino-1,2-dihydro-2,2-tetramethylene-s-triazine-1-yl)-1,6-hexanediol dihydrochloride] was active in vitro against the sleeping sickness-causing agentsTrypanosoma bruceisubsp.rhodesienseandT. bruceisubsp.gambiense; against a multidrug-resistant organism,T. bruceisubsp.brucei; and against animal-pathogenic organismsTrypanosoma evansi,Trypanosoma equiperdum, andTrypanosoma congolense; but not against the intracellular parasitesTrypanosoma cruziandLeishmania donovani. Cytotoxic effects against mammalian cells were observed at approximately 106-fold higher concentrations than those necessary to inhibitT. bruceisubsp.rhodesiense. Trybizine hydrochloride was able to eliminateT. bruceisubsp.rhodesienseandT. bruceisubsp.gambiensein an acute rodent model with four intraperitoneal doses of 0.25 mg kg of body weight−1or four doses of 1 mg kg−1, respectively, or with four oral doses of 20 mg kg−1. The compound expressed activity against suramin-resistantT. evansistrains in mice. However, these concentrations were not sufficient to cure mice infected with multidrug-resistantT. bruceisubsp.brucei. A late-stage rodent model with central nervous system involvement could not be cured, indicating that trybizine may not pass the blood-brain barrier in sufficient quantities.
Sordarins: In Vitro Activities of New Antifungal Derivatives against Pathogenic Yeasts,
Pneumocystis carinii
, and Filamentous Fungi
Authors: Herreros E. , Martinez C. M. , Almela M. J. , Marriott M. S. , De Las Heras F. Gomez , Gargallo-Viola D.
Published: October 2018

GM 193663, GM 211676, GM 222712, and GM 237354 are new semisynthetic derivatives of the sordarin class. The in vitro antifungal activities of GM 193663, GM 211676, GM 222712, and GM 237354 against 111 clinical yeast isolates of
Candida albicans
,
Candida kefyr
,
Candida glabrata
,
Candida parapsilosis
,
Candida krusei
, and
Cryptococcus neoformans
were compared. The in vitro activities of some of these compounds against
Pneumocystis carinii
, 20 isolates each of
Aspergillus fumigatus
and
Aspergillus flavus
, and 30 isolates of emerging less-common mold pathogens and dermatophytes were also compared. The MICs of GM 193663, GM 211676, GM 222712, and GM 237354 at which 90% of the isolates were inhibited (MIC
90
s) were 0.03, 0.03, 0.004, and 0.015 μg/ml, respectively, for
C. albicans
, including strains with decreased susceptibility to fluconazole; 0.5, 0.5, 0.06, and 0.12 μg/ml, respectively, for
C. tropicalis
; and 0.004, 0.015, 0.008, and 0.03 μg/ml, respectively, for
C. kefyr
. GM 222712 and GM 237354 were the most active compounds against
C. glabrata
,
C. parapsilosis
, and
Cryptococcus neoformans
. Against
C. glabrata
and
C. parapsilosis
, the MIC
90
s of GM 222712 and GM 237354 were 0.5 and 4 μg/ml and 1 and 16 μg/ml, respectively. The MIC
90
s of GM 222712 and GM 237354 against
Cryptococcus neoformans
were 0.5 and 0.25 μg/ml, respectively. GM 193663, GM 211676, GM 222712, and GM 237354 were extremely active against
P. carinii
. The efficacies of sordarin derivatives against this organism were determined by measuring the inhibition of the uptake and incorporation of radiolabelled methionine into newly synthesized proteins. All compounds tested showed 50% inhibitory concentrations of <0.008 μg/ml. Against
A. flavus
and
A. fumigatus
, the MIC
90
s of GM 222712 and GM 237354 were 1 and 32 μg/ml and 32 and >64 μg/ml, respectively. In addition, GM 237354 was tested against the most important emerging fungal pathogens which affect immunocompromised patients.
Cladosporium carrioni
,
Pseudallescheria boydii
, and the yeast-like fungi
Blastoschizomyces capitatus
and
Geotrichum clavatum
were the most susceptible of the fungi to GM 237354, with MICs ranging from ≤0.25 to 2 μg/ml. The MICs of GM 237354 against
Trichosporon beigelii
and the zygomycetes
Absidia corymbifera
,
Cunninghamella bertholletiae
, and
Rhizopus arrhizus
ranged from ≤0.25 to 8 μg/ml. Against dermatophytes, GM 237354 MICs were ≥2 μg/ml. In summary, we concluded that some sordarin derivatives, such as GM 222712 and GM 237354, showed excellent in vitro activities against a wide range of pathogenic fungi, including
Candida
spp.,
Cryptococcus neoformans
,
P. carinii
, and some filamentous fungi and emerging invasive fungal pathogens.
Display of Functional β-Lactamase Inhibitory Protein on the Surface of M13 Bacteriophage
Authors: Huang Wanzhi , Petrosino Joseph , Palzkill Timothy
Published: October 2018

The display of proteins on the surface of filamentous phage has been shown to be a powerful method to select variants of a protein with altered binding properties from large combinatorial libraries of mutants. The β-lactamase inhibitory protein (BLIP) is a 165-amino-acid protein that binds and inhibits TEM-1 β-lactamase-catalyzed hydrolysis of the penicillin and cephalosporin antibiotics. Here we describe the construction of a new phagemid vector and the use of this vector to display BLIP on the surface of filamentous phage. It is shown that BLIP-displaying phage bind to immobilized β-lactamase and that the binding can be competed off by the addition of soluble β-lactamase. In addition, a two-step phage enzyme-linked immunosorbent assay procedure was used to demonstrate that the BLIP-displaying phage bind β-lactamase with a 50% inhibitory concentration of 1 nM, which compares favorably with a previously published

K
i

of 0.6 nM. A system has therefore been established for protein engineering of BLIP to expand its range of binding to other β-lactamases and penicillin-binding proteins.
Drift in Susceptibility of
Neisseria gonorrhoeae
to Ciprofloxacin and Emergence of Therapeutic Failure
Authors: Ison Catherine A. , Woodford Patricia J. , Madders Helen , Claydon Elizabeth
Published: October 2018

Ciprofloxacin, 500 mg, was introduced as the first-line therapy for gonorrhea at St. Mary’s Hospital, London, in 1989, when a surveillance program was initiated to detect the emergence of resistance. Isolates of
Neisseria gonorrhoeae
from consecutive patients attending the Jefferiss Wing, Genitourinary Medicine Clinic at St. Mary’s Hospital, between 1989 and 1997 have been tested for susceptibility to ciprofloxacin by using an agar dilution breakpoint technique. Isolates considered potentially resistant (MIC, >0.12 μg/ml) were further characterized by determination of the MICs of ciprofloxacin, nalidixic acid, and penicillin, auxotyped and serotyped, and screened for mutations in the DNA gyrase gene,
gyrA
, and the topoisomerase IV gene,
parC
. A total of 4,875 isolates were tested. While the majority of isolates were highly susceptible (MIC, ≤0.008 μg of ciprofloxacin/ml), there was a drift toward reduced susceptibility in
N. gonorrhoeae
isolated between 1993 and 1996 (
P
< 0.001). In 1997 this drift was reduced but remained above pre-1993 levels. Isolates from 18 patients were classed as potentially resistant (MIC, >0.12 μg/ml); all of these belonged to serogroup B, and NR/IB-1 was the most common auxotype/serovar class. The infections in 14 of the 18 patients were known to be acquired abroad, and 5 were known to result in therapeutic failure. The surveillance program has established that ciprofloxacin is still a highly effective antibiotic against
N. gonorrhoeae
in this population. However, it has identified a drift in susceptibility which may have resulted from increased usage of ciprofloxacin. High-level resistance has now emerged, although treatment failure is still uncommon.
The Epstein-Barr Virus Thymidine Kinase Does Not Phosphorylate Ganciclovir or Acyclovir and Demonstrates a Narrow Substrate Specificity Compared to the Herpes Simplex Virus Type 1 Thymidine Kinase
Authors: Gustafson Erik A. , Chillemi Antoinette C. , Sage David R. , Fingeroth Joyce D.
Published: October 2018

The Epstein-Barr virus (EBV) thymidine kinase (TK) was expressed in mammalian 143B TK
−
cells to investigate its substrate specificity. The herpes simplex virus type 1 (HSV-1) TK was similarly expressed for comparison. Both viral TKs conferred a TK
+
phenotype on 143B TK
−
cells. The nucleoside analog ganciclovir (GCV) did not affect the growth of 143B EBV TK or 143B TK
−
cells but effectively killed 143B HSV-1 TK cells. Furthermore, lysates of 143B EBV TK cells could not phosphorylate GCV, which was confirmed by high-performance liquid chromatography. EBV TK, HSV-1 TK, and EBV TK N
−
, a truncated EBV TK missing 243 N-terminal amino acids, were purified as fusion proteins expressed in bacteria, and all had TK activity. In addition, EBV TK was observed to have a thymidylate kinase activity but could not phosphorylate GCV, acyclovir, or 2′-deoxycytidine. In competition assays, only nucleoside analogs of thymidine significantly inhibited thymidine phosphorylation by EBV TK, with the following rank order: 5-bromodeoxyuridine > zidovudine > stavudine > sorivudine. These results demonstrate that EBV TK substrate specificity is narrower than those of alphaherpesvirus TKs and that thymidine analogs may be the most suitable nucleoside antivirals to target the enzyme. Clinical implications for gammaherpesviruses are discussed.
Fluconazole versus
Candida albicans
: A Complex Relationship
Authors: Graybill John R. , Montalbo Eleanor , Kirkpatrick William R. , Luther Michael F. , Revankar Sanjay G. , Patterson Thomas F.
Published: October 2018

A murine model of systemic candidiasis was used to assess the virulence of serial
Candida albicans
strains for which fluconazole MICs were increasing. Serial isolates from five patients with 17 episodes of oropharyngeal candidiasis were evaluated. The MICs for these isolates exhibited at least an eightfold progressive increase from susceptible (MIC < 8 μg/ml; range, 0.25 to 4 μg/ml) to resistant (MIC ≥ 16 μg/ml; range, 16 to ≥128 μg/ml). Virulence of the serial isolates from three of five patients showed a more than fivefold progressive decrease in the dose accounting for 50% mortality and was associated with development of fluconazole resistance. Low doses of fluconazole prolonged survival of mice infected with susceptible yeasts but failed to prolong survival following challenge with a resistant strain. In addition, a decreased burden of renal infection was noted in mice challenged with two of the three resistant strains. This was consistent with reduced virulence. Fluconazole did not further decrease the level of infection. In the isolates with a decrease in virulence, two exhibited overexpression of
CDR
, which encodes an ABC drug efflux pump. In contrast, serial isolates from the remaining two patients with the development of resistance did not demonstrate a change in virulence and fluconazole remained effective in prolonging survival, although significantly higher doses of fluconazole were required for efficacy. Resistant isolates from both of these patients exhibited overexpression of
MDR
. This study demonstrates that decreased virulence of serial
C. albicans
isolates is associated with increasing fluconazole MICs in some cases but not in others and shows that these low-virulence strains may not consistently cause infection.
Activities of New Fluoroquinolones against Fluoroquinolone-Resistant Pathogens of the Lower Respiratory Tract
Authors: Piddock Laura J. V. , Johnson M. , Ricci V. , Hill S. L.
Published: October 2018

The activities of six new fluoroquinolones (moxifloxacin, grepafloxacin, gatifloxacin, trovafloxacin, clinafloxacin, and levofloxacin) compared with those of sparfloxacin and ciprofloxacin with or without reserpine (20 μg/ml) were determined for 19
Streptococcus pneumoniae
isolates, 5
Haemophilus
sp. isolates, and 10
Pseudomonas aeruginosa
isolates with decreased susceptibility to ciprofloxacin from patients with clinically confirmed lower respiratory tract infections. Based upon the MICs at which 50% of isolates were inhibited (MIC
50
s) and MIC
90
s, the most active agent was clinafloxacin, followed by (in order of decreasing activity) trovafloxacin, moxifloxacin, gatifloxacin, sparfloxacin, and grepafloxacin. Except for clinafloxacin (and gatifloxacin and trovafloxacin for
H. influenzae
), none of the new agents had improved activities compared with that of ciprofloxacin for
P. aeruginosa
and
H. influenzae
. A variable reserpine effect was observed for ciprofloxacin and
S. pneumoniae
; however, for 9 of 19 (47%) isolates the MIC of ciprofloxacin was decreased by at least fourfold, suggesting the presence of an efflux pump contributing to the resistance phenotype. The laboratory
parC
(Ser79) mutant strain of
S. pneumoniae
required eightfold more ciprofloxacin for inhibition than the wild-type strain, but there was no change in the MIC of sparfloxacin and only a 1-dilution increase in the MICs of the other agents. For efflux pump mutant
S. pneumoniae
the activities of all the newer agents, except for levofloxacin, were reduced. Except for clinafloxacin, all second-step laboratory mutants required at least 2 μg of all fluoroquinolones per ml for inhibition.
Prospective Randomized Comparison of Imipenem-Cilastatin and Piperacillin-Tazobactam in Nosocomial Pneumonia or Peritonitis
Authors: Jaccard C. , Troillet N. , Harbarth S. , Zanetti G. , Aymon D. , Schneider R. , Chiolero R. , Ricou B. , Romand J. , Huber O. , Ambrosetti P. , Praz G. , Lew D. , Bille J. , Glauser M. P. , Cometta A.
Published: October 2018

Nosocomial pneumonia and acute peritonitis may be caused by a wide array of pathogens, and combination therapy is often recommended. We have previously shown that imipenem-cilastatin monotherapy was as efficacious as the combination of imipenem-cilastatin plus netilmicin in these two settings. The efficacy of imipenem-cilastatin is now compared to that of piperacillin-tazobactam as monotherapy in patients with nosocomial pneumonia or acute peritonitis. Three hundred seventy one patients with nosocomial pneumonia or peritonitis were randomly assigned to receive either imipenem-cilastatin (0.5 g four times a day) or piperacillin-tazobactam (4.5 g three times a day). Three hundred thirteen were assessable (154 with nosocomial pneumonia and 159 with peritonitis). For nosocomial pneumonia, clinical-failure rates in the piperacillin-tazobactam group (13 of 75 [17%]) and in the imipenem-cilastatin group (23 of 79 [29%]) were similar (
P
= 0.09), as were the numbers of deaths due to infection (6 in the imipenem-cilastatin group [8%], 7 in the piperacillin-tazobactam group [9%]) (
P
= 0.78). For acute peritonitis, clinical success rates were comparable (piperacillin-tazobactam, 72 of 76 [95%]; imipenem-cilastatin, 77 of 83 [93%]). For infections due to
Pseudomonas aeruginosa
, 45 patients had nosocomial pneumonia (21 in the piperacillin-tazobactam group and 24 in the imipenem-cilastatin group) and 10 had peritonitis (5 in each group). In the patients with nosocomial pneumonia, clinical failure was less frequent in the piperacillin-tazobactam group (2 of 21 [10%]) than in the piperacillin-cilastatin group (12 of 24 [50%]) (
P
= 0.004). Bacterial resistance to allocated regimen was the main cause of clinical failure (1 in the piperacillin-tazobactam group and 12 in the imipenem-cilastatin group). For the patients with peritonitis, no difference in clinical outcome was observed (five of five cured in each group). The overall frequencies of adverse events related to treatment in the two groups were similar (24 in the piperacillin-tazobactam group, 22 in the imipenem-cilastatin group). Diarrhea was significantly more frequent in the piperacillin-tazobactam group (10 of 24) than in the imipenem-cilastatin group (2 of 22). This study suggests that piperacillin-tazobactam monotherapy is at least as effective and safe as imipenem-cilastatin monotherapy in the treatment of nosocomial pneumonia or peritonitis. In
P. aeruginosa
pneumonia, piperacillin-tazobactam achieved a better clinical efficacy than imipenem-cilastatin, due to reduced development of microbiological resistance. Tolerance was comparable, with the exception of diarrhea, which was more frequent with piperacillin-tazobactam.
Antimicrobial Susceptibilities of
Porphyromonas gingivalis
,
Prevotella intermedia
, and
Prevotella nigrescens
spp. Isolated in Spain
Authors: Andrés María T. , Chung Whasun O. , Roberts Marilyn C. , Fierro José F.
Published: October 2018

The susceptibilities of 143
Porphyromonas gingivalis
,
Prevotella intermedia
, and
Prevotella nigrescens
isolates to 18 antimicrobial agents were tested. All
P. gingivalis
isolates were susceptible. In contrast, some
Prevotella
spp. (17%) were resistant to β-lactams, erythromycin, clindamycin, or tetracycline and carried resistance genes,
ermF
or
tetQ
, or β-lactamases.
Activity of HMR 3647 Compared to Those of Five Agents against
Haemophilus influenzae
and
Moraxella catarrhalis
by MIC Determination and Time-Kill Assay
Authors: Pankuch Glenn A. , Hoellman Dianne B. , Lin Gengrong , Bajaksouzian Saralee , Jacobs Michael R. , Appelbaum Peter C.
Published: October 2018

The microdilution MICs of HMR 3647, erythromycin A, azithromycin, clarithromycin, roxithromycin, and pristinamycin against 50/90% of 249
Haemophilus influenzae
and 50
Moraxella catarrhalis
isolates were 2/4, 0.06/0.125; 8/16, 0.25/0.25; 2/4, 0.06/0.125; 16/16, 0.25/0.25; 32/>32, 1/2; and 2/4, 0.5/0.5 μg/ml. Azithromycin was bactericidal against all 10
H. influenzae
and 3 of 5
M. catarrhalis
isolates and HMR 3647, erythromycin A, clarithromycin, roxithromycin, and pristinamycin were bacteriostatic, against all 15 strains after 24 h at the MIC.
Evaluation of Once-Weekly Therapy for Tuberculosis Using Isoniazid plus Rifamycins in the Mouse Aerosol Infection Model
Authors: Brooks Jason V. , Orme Ian M.
Published: October 2018

Once-weekly therapy with combinations of isoniazid plus a rifamycin was tested in the mouse low-dose aerosol infection model against two strains ofMycobacterium tuberculosis. Combinations of isoniazid and rifalizil and isoniazid and rifapentine were both highly effective. These animal model data thus support the evaluation of these regimens under clinical conditions.
Efficacy of Low-Dose Dopamine in Preventing Amphotericin B Nephrotoxicity in Bone Marrow Transplant Patients and Leukemia Patients
Authors: Camp Mary J. , Wingard John R. , Gilmore Claire E. , Lin Lillian S. , Dix Suzanne P. , Davidson Terry G. , Geller Robert B.
Published: October 2018

This study evaluated the efficacy of low-dose dopamine for prevention of amphotericin B-induced nephrotoxicity in autologous bone marrow transplant and leukemia patients. Seventy-one patients undergoing cytoreductive therapy who required amphotericin B were randomly assigned in an unblinded fashion to a group receiving continuous-infusion low-dose dopamine (3 μg/kg/min) or a group receiving no dopamine. Amphotericin B was dosed at 0.5 or 1.0 mg/kg/day based on computerized tomography scan results or presence of positive blood cultures. No patient received saline boluses. The rate of nephrotoxicity, severity as graded by Southwest Oncology Group toxicity criteria, and time to each grade of nephrotoxicity were compared between the two groups. Eighty percent of the no-dopamine group and 66.7% of the dopamine group developed nephrotoxicity, defined as a 1.5-fold or greater increase in baseline serum creatinine level (
P
= 0.20). No statistical difference was noted at any grade of nephrotoxicity between the two groups. Thirty-four percent of patients in the no-dopamine group versus 17.6% in the dopamine group had a 2.5-fold or greater increase in serum creatinine level, which was not statistically significant (
P
= 0.0888). Ten patients developed grade IV nephrotoxicity and were withdrawn from the study, 7 in the no-dopamine group and 3 in the dopamine group (
P
= 0.19). The time to each grade of nephrotoxicity was also not significantly different for the two groups. Eleven adverse drug reactions were reported in the dopamine group in comparison to one in the no-dopamine group. Thus, dopamine offers little in the way of prevention of nephrotoxicity associated with amphotericin B therapy. Although the significance of drug reactions in the dopamine group is not clearly established due to lack of cardiac monitoring in the no-dopamine group, dopamine therapy is not without complications.
Novel OXA-10-Derived Extended-Spectrum β-Lactamases Selected In Vivo or In Vitro
Authors: Mugnier P. , Casin I. , Bouthors A. T. , Collatz E.
Published: October 2018

A clinical isolate of
Pseudomonas aeruginosa
, PAe191, was found to be highly resistant to all anti-
Pseudomonas
β-lactam antibiotics (except imipenem) and resistant also to aminoglycosides. It produced a β-lactamase (with an apparent pI of 7.6) which was not inhibited by clavulanic acid. Cloning and characterization of the β-lactamase gene showed that it coded for a novel extended-spectrum OXA-10 variant, called OXA-19, which differed from OXA-10 by nine amino acids and from OXA-13 by two, i.e., Asn in position 73 (Asn73) instead of Ser and Asp157 instead of Gly. Asparagine in position 157 is implicated in resistance to ceftazidime, while the amino acid in position 73, in this variant, seems to condition the level of resistance to penicillins. The
oxa19
gene was found to be inserted, in a typical integron structure, immediately downstream from an
aac
(
6
′)-
Ib
gene coding for an aminoglycoside acetyltransferase variant, which was called AAC(6′)-Ib
9
.
Pharmacokinetics, Distribution in Serum Lipoproteins and Tissues, and Renal Toxicities of Amphotericin B and Amphotericin B Lipid Complex in a Hypercholesterolemic Rabbit Model: Single-Dose Studies
Authors: Wasan Kishor M. , Kennedy Allison L. , Cassidy Shawn M. , Ramaswamy Manisha , Holtorf Lorilynne , Chou Jenny Wen-Lin , Pritchard P. Haydn
Published: October 2018

The purpose of this study was to determine if a relationship exists among total serum and lipoprotein cholesterol concentration, the severity of amphotericin B (AmpB)-induced renal toxicity, and the serum pharmacokinetics of AmpB in hypercholesterolemic rabbits administered AmpB and AmpB lipid complex (ABLC). After 10 days of cholesterol-enriched diet (0.50% [wt/vol]) or regular rabbit diet (control), each rabbit was administered a single intravenous bolus of AmpB or ABLC (1.0 mg/kg of body weight). Blood samples were obtained before administration and serially thereafter for the assessment of serum pharmacokinetics, kidney toxicity, and serum lipoprotein distribution. Rabbits were humanely sacrificed after all blood samples were obtained, and tissues were harvested for drug analysis. Before drug treatment, cholesterol-fed rabbits demonstrated marked increases in total serum cholesterol and low-density lipoprotein (LDL) cholesterol levels compared with levels in rabbits on a regular diet. No significant differences in triglyceride levels were observed. A significant increase in serum creatinine levels was observed in cholesterol-fed and regular diet-fed rabbits administered AmpB. However, the magnitude of this increase was 2.5-fold greater in cholesterol-fed rabbits than in regular diet-fed rabbits. No significant differences in triglyceride levels were observed. A significant increase in serum creatinine levels was observed in cholesterol-fed and regular diet-fed rabbits administered ABLC. Whereas AmpB pharmacokinetics were significantly altered in cholesterol-fed rabbits administered free AmpB, similar AmpB pharmacokinetics were observed in both rabbit groups administered ABLC. Renal AmpB levels were significantly increased in cholesterol-fed rabbits administered AmpB compared with those in all other groups. Hepatic and lung AmpB levels were elevated in cholesterol-fed rabbits administered free AmpB compared to controls. In addition, hepatic, lung, and spleen AmpB levels were significantly decreased in cholesterol-fed rabbits administered ABLC compared to controls. An increased percentage of AmpB was recovered in LDL–very-low-density lipoprotein fraction when free AmpB was administered to cholesterol-fed rabbits compared with those in all other groups. These findings suggest that increases in cholesterol, specifically, LDL cholesterol levels, modify the disposition and renal toxicity of free AmpB. However, the pharmacokinetics and renal toxicity of ABLC were independent of elevations in total and LDL cholesterol levels.
Antibacterial Effects of Levofloxacin, Erythromycin, and Rifampin in a Human Monocyte System against
Legionella pneumophila
Authors: Baltch Aldona L. , Smith Raymond P. , Franke Mary A. , Michelsen Phyllis B.
Published: October 2018

The antibacterial activities of levofloxacin, erythromycin, and rifampin against intracellular
Legionella pneumophila
L-1033, serogroup 1, were studied. In an in vitro system utilizing adherent human monocytes,
L. pneumophila
L-1033, a phagocytosis time period of 1 h, and antibiotic (levofloxacin, erythromycin, and/or rifampin) at 1 to 10 times the MIC, the CFU/ml values for the monocyte lysate were determined during 0- to 4-day time periods. The decrease in CFU/ml with levofloxacin at pH 7.4 was rapid, occurring within 24 h, and was drug concentration dependent (
P
< 0.01). The decrease in CFU with rifampin was first observed at 48 h (
P
< 0.01), while only a minimal decrease in CFU/ml was observed with erythromycin. Combination of levofloxacin and rifampin and of levofloxacin and erythromycin at ten times their MICs significantly decreased the CFU/ml value (
P
< 0.01), to the value attained by levofloxacin alone, while combination of rifampin and erythromycin did not. Removal of levofloxacin after 24 h of incubation resulted in regrowth of
L. pneumophila
L-1033, while a continued slow decrease in CFU/ml was seen following rifampin removal; CFU/ml values were unaffected by the removal of erythromycin. At 4 days, and even in assays performed following antibiotic removal, the CFU/ml value continued to be lower in the levofloxacin and rifampin assays than in the assays with erythromycin. Levofloxacin had a significantly higher bactericidal activity against
L. pneumophila
L-1033 than erythromycin or rifampin. In these assays, the addition of erythromycin or rifampin did not affect the antibacterial activity of levofloxacin.
Characterization of a Chromosomal Gene Encoding Type B β-Lactamase in Phage Group II Isolates of
Staphylococcus aureus
Authors: Voladri Rama Kishan R. , Kernodle Douglas S.
Published: October 2018

In contrast to most
Staphylococcus aureus
isolates in which the gene for staphylococcal β-lactamase (
blaZ
) is plasmid borne, isolates typeable by group II bacteriophages frequently carry
blaZ
on the chromosome. Furthermore, the chromosomal gene encodes the type B variant of staphylococcal β-lactamase for which the nucleotide and deduced amino acid sequences have not yet been reported. To better understand β-lactamase production among phage group II staphylococci and the nature of the type B β-lactamase, we determined the type and amount of enzyme produced by 24 phage group II isolates. Of these isolates, 1 did not produce β-lactamase, 8 produced the type B enzyme, and 15 produced the type C enzyme. In all eight type B β-lactamase-producing isolates,
blaZ
was located on the chromosome. This was in contrast to the type C β-lactamase-producing isolates, in which
blaZ
was located on a 21-kb plasmid. The nucleotide sequence corresponding to the leader peptide and the N-terminal 85% of the mature exoenzyme form of type B
S. aureus
was determined. The deduced amino acid sequence revealed 3 residues in the leader peptide and 12 residues in the exoenzyme portion of the β-lactamase that differ from the prototypic type A β-lactamase sequence. These include the serine-to-asparagine change at residue 216 found in the kinetically similar type C enzyme, a threonine-to-lysine change at residue 128 close to the SDN loop (residues 130 to 132), and several substitutions not found in any of the other staphylococcal β-lactamases. In summary, modern isolates of
S. aureus
typeable by group II phages produce type B or type C staphylococcal β-lactamase. The type B gene resides on the chromosome and has a sequence that, when compared to the sequences of the other staphylococcal β-lactamases, corresponds well with its kinetic properties.
The Antiherpesvirus Activity of H2G [(
R
)-9-[4-Hydroxy-2-(Hydroxymethyl)Butyl]Guanine] Is Markedly Enhanced by the Novel Immunosuppressive Agent Mycophenolate Mofetil
Authors: Neyts Johan , Andrei Graciela , De Clercq Erik
Published: October 2018

Mycophenolate mofetil (MMF) has been approved as an immunosuppressive agent in kidney transplant recipients and may thus be used concomitantly with antiherpetic agents, which are used for the treatment of intercurrent herpesvirus infections. We have recently demonstrated that MMF and its parent compound mycophenolic acid (MPA), which is a potent inhibitor of IMP dehydrogenase, potentiate the antiherpesvirus activity of acyclovir, ganciclovir, and penciclovir. We have now evaluated the antiviral efficacy of the combination of MPA and the novel antiherpesvirus agent H2G [(
R
)-9-[4-hydroxy-2-(hydroxymethyl)butyl]guanine]. When combined with H2G, MPA (at concentrations ranging from 0.25 to 10 μg/ml, which are readily attainable in human plasma) markedly potentiated the antiviral efficacy of H2G against herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2), as reflected by a 10- to 150-fold decrease in the 50% effective concentration. Moreover, the activity of H2G against a thymidine kinase-deficient strain of HSV-1 (TK
−
HSV-1) was increased more than 2,500-fold when combined with MPA. MPA by itself had little or no effect on the replication of these viruses. Similar observations were made for varicella-zoster virus. Also, ribavirin (another inhibitor of IMP dehydrogenase) caused a marked enhancement of the activity of H2G against HSV-1 (10-fold), HSV-2 (10-fold), and TK
−
HSV-1 (>185-fold). Exogenously added guanosine reversed the potentiating effects of MPA on the antiviral activity of H2G, indicating that this potentiating effect resulted from a depletion of the endogenous dGTP pools, thus favoring the inhibitory action of the H2G triphosphate on the viral DNA polymerase.
An
ampD
Gene in
Pseudomonas aeruginosa
Encodes a Negative Regulator of AmpC β-Lactamase Expression
Authors: Langaee Taimour Yousef , Dargis Michèle , Huletsky Ann
Published: October 2018

The
ampD
and
ampE
genes of
Pseudomonas aeruginosa
PAO1 were cloned and characterized. These genes are transcribed in the same orientation and form an operon. The deduced polypeptide of
P. aeruginosa ampD
exhibited more than 60% similarity to the AmpD proteins of enterobacteria and
Haemophilus influenzae
. The
ampD
product transcomplemented
Escherichia coli ampD
mutants to wild-type β-lactamase expression.
Macrolide Susceptibility and β-Lactamase Production among
Haemophilus influenzae
Isolates in the United States, 1996–1997
Authors: Hogan Patricia A. , Sheehan Daniel J.
Published: October 2018

In 1996 and 1997, 68 hospital laboratories throughout the United States determined the β-lactamase production and susceptibility to macrolides of 1,998 isolates of
Haemophilus influenzae
obtained from patients with community-acquired respiratory tract infections. The MICs at which 90% of the isolates are inhibited of azithromycin, erythromycin, and clarithromycin were 4, 8, and 16 μg/ml, respectively. By National Committee for Clinical Laboratory Standards interpretive criteria, 99 and 78% of the isolates were susceptible to azithromycin and clarithromycin, respectively. The prevalence of β-lactamase production was 32%.
In Vitro Activities of Several Diaminomethylpyridopyrimidines against
Mycobacterium avium
Complex
Authors: Shoen Carolyn M. , Choromanska Olga , Reynolds Robert C. , Piper James R. , Johnson Cheryl A. , Cynamon Michael H.
Published: October 2018

Three recently synthesized dihydrofolate reductase (DHFR) inhibitors designated SoRI 8890, 8895, and 8897 were evaluated for their in vitro activities against 25 isolates of
Mycobacterium avium
complex. The MICs at which 50 and 90% of isolates were inhibited were 1 and 2, 4 and 8, and 4 and 8 μg/ml for SoRI 8890, 8895, and 8897, respectively. Although the addition of dapsone at 0.5 μg/ml did not significantly enhance the in vitro activities of these compounds, their activities alone were comparable to, if not better than, results seen with other DHFR inhibitors, such as pyrimethamine or WR99210.
Examination of Methicillin-Resistant and Methicillin-Susceptible
Staphylococcus aureus
Mutants with Low-Level Fluoroquinolone Resistance
Authors: Sulavik Mark C. , Barg Neil L.
Published: October 2018

For
Staphylococcus aureus
, stepwise mutations result in high-level quinolone resistance. Methicillin-resistant and -susceptible quinolone-resistant, first-step mutants generated in vitro were obtained and found to be no different than those recovered from murine abscesses. Approximately 10% of all first-step mutants were resistant to ethidium bromide, and selected strains had mutations that mapped to
flqB
. NorA-mediated resistance among first-step mutants may be more prevalent than previously reported.
In Vitro Activities of Cefminox against Anaerobic Bacteria Compared with Those of Nine Other Compounds
Authors: Hoellman Dianne B. , Spangler Sheila K. , Jacobs Michael R. , Appelbaum Peter C.
Published: October 2018

The agar dilution MIC method was used to test the activity of cefminox, a β-lactamase-stable cephamycin, compared with those of cefoxitin, cefotetan, moxalactam, ceftizoxime, cefotiam, cefamandole, cefoperazone, clindamycin, and metronidazole against 357 anaerobes. Overall, cefminox was the most active β-lactam, with an MIC at which 50% of isolates are inhibited (MIC
50
) of 1.0 μg/ml and an MIC
90
of 16.0 μg/ml. Other β-lactams were less active, with respective MIC
50
s and MIC
90
s of 2.0 and 64.0 μg/ml for cefoxitin, 2.0 and 128.0 μg/ml for cefotetan, 2.0 and 64.0 μg/ml for moxalactam, 4.0 and >128.0 μg/ml for ceftizoxime, 16.0 and >128.0 μg/ml for cefotiam, 8.0 and >128.0 μg/ml for cefamandole, and 4.0 and 128.0 μg/ml for cefoperazone. The clindamycin MIC
50
and MIC
90
were 0.5 and 8.0 μg/ml, respectively, and the metronidazole MIC
50
and MIC
90
were 1.0 and 4.0 μg/ml, respectively. Cefminox was especially active against
Bacteroides fragilis
(MIC
90
, 2.0 μg/ml),
Bacteroides thetaiotaomicron
(MIC
90
, 4.0 μg/ml), fusobacteria (MIC
90
, 1.0 μg/ml), peptostreptococci (MIC
90
, 2.0 μg/ml), and clostridia, including
Clostridium difficile
(MIC
90
, 2.0 μg/ml). Time-kill studies performed with six representative anaerobic species revealed that at the MIC all compounds except ceftizoxime were bactericidal (99.9% killing) against all strains after 48 h. At 24 h, only cefminox and cefoxitin at 4× the MIC and cefoperazone at 8× the MIC were bactericidal against all strains. After 12 h, at the MIC all compounds except moxalactam, ceftizoxime, cefotiam, cefamandole, clindamycin, and metronidazole gave 90% killing of all strains. After 3 h, cefminox at 2× the MIC produced the most rapid effect, with 90% killing of all strains.
Diversity of VanA Glycopeptide Resistance Elements in Enterococci from Humans and Nonhuman Sources
Authors: Woodford Neil , Adebiyi Antoinette-Mary A. , Palepou Marie-France I. , Cookson Barry D.
Published: October 2018

Elements mediating VanA glycopeptide resistance in 106 diverse enterococci from humans and nonhuman sources were compared with the prototype VanA transposon, Tn
1546
, in
Enterococcus faecium
BM4147. The isolates included 64 from individual patients at 15 hospitals in the United Kingdom (isolated between 1987 and 1996) and 42 from nonhuman sources in the United Kingdom (27 from raw meat, 7 from animal feces, and 8 from sewage). VanA elements were assigned to 24 groups (designated groups A to X) with primers that amplified 10 overlapping fragments of Tn
1546
. Ten groups of elements were found only in human enterococci, eight groups of elements were unique to nonhuman strains, and six groups of elements were common in enterococci from all sources. Elements indistinguishable from Tn
1546
(group A) were observed more frequently in enterococci from nonhuman sources (34 versus 9%) but were identified in enterococci that caused outbreaks in hospital patients between 1987 and 1995. The most common group found in human enterococci (group H; 33%) was rarely observed in enterococci from other sources (5%). Group H elements differed from Tn
1546
in three regions and included a novel insertion sequence, designated IS
1542
, between
orf2
and
vanR
. The VanA elements of 14 other groups had a similar insertion at this position and/or distinct insertions at other positions. We conclude that VanA elements in enterococci are heterogeneous, although all show regions of homology with Tn
1546
. Furthermore, the elements most common among the human and nonhuman enterococci studied were different. This approach may be useful for monitoring the evolution of VanA resistance and may also be applicable in local “snapshot” epidemiological studies. However, as transposition events involving insertion sequences accounted for the differences observed between several groups, the stability of the elements must be assessed before their true epidemiological significance can be determined.
In Vitro Antimalarial Activity of a New Organometallic Analog, Ferrocene-Chloroquine
Authors: Domarle O. , Blampain G. , Agnaniet H. , Nzadiyabi T. , Lebibi J. , Brocard J. , Maciejewski L. , Biot C. , Georges A. J. , Millet P.
Published: October 2018

The in vitro activities of new organometallic chloroquine analogs, based on 4-amino-quinoleine compounds bound to a molecule of ferrocene, were evaluated against chloroquine-susceptible, chloroquine-intermediate, and chloroquine-resistant, culture-adapted
Plasmodium falciparum
lineages by a proliferation test. One of the ferrocene analogs totally restored the activity of chloroquine against chloroquine-resistant parasites. This compound, associated with tartaric acid for better solubility, was highly effective. The role of the ferrocene in reversing chloroquine resistance is discussed, as is its potential use for human therapy.
Covalent Polymyxin B Conjugate with Human Immunoglobulin G as an Antiendotoxin Reagent
Authors: Drabick Joseph J. , Bhattacharjee Apurba K. , Hoover David L. , Siber George E. , Morales Vivian E. , Young Lynnette D. , Brown Scott L. , Cross Alan S.
Published: October 2018

Polymyxin B (PMB) is a cyclic decapeptide antibiotic which also binds and neutralizes endotoxin. Unfortunately, PMB can be considerably nephrotoxic at clinically utilized doses, thereby limiting its utility as a therapeutic antiendotoxin reagent. We sought to change the pharmacokinetics and toxicity profile of PMB by covalently linking it to a human immunoglobulin G (IgG) carrier. Conjugates of PMB with IgG were prepared by EDAC [1-ethyl-3-(3-dimethylaminopropyl) carbodiimide]-mediated amide formation. Analysis by dot enzyme-linked immunosorbent assay with an anti-PMB monoclonal antibody showed that the purified conjugate contained bound PMB. The IgG-PMB conjugate reacted with lipid A and J5 lipopolysaccharide in Western blot assays in a manner comparable to that of whole antiserum with anti-lipid A reactivity; unconjugated IgG had no reactivity. The PMB bound in the conjugate retained its endotoxin-neutralizing activity compared to that of unbound PMB as evidenced by its dose-dependent inhibition of tumor necrosis factor release by endotoxin-stimulated human monocytes in vitro; unconjugated IgG had no activity. By this assay, the PMB-IgG conjugate was determined to have approximately 3.0 μg of bound functional PMB per 100 μg of total protein of conjugate (five molecules of PMB per IgG molecule). The PMB-IgG conjugate was also bactericidal against clinical strains ofEscherichia coli,Pseudomonas aeruginosa, andKlebsiella pneumoniaerelative to unconjugated IgG with MBCs of <4 μg of conjugate per ml for each of the tested strains. The conjugate appeared to be nontoxic at the highest doses deliverable and provided statistically significant protection from death to galactosamine-sensitized, lipopolysaccharide-challenged mice in a dose-dependent fashion when administered prophylactically 2 h before challenge. However, neither free PMB nor the PMB-IgG conjugate could protect mice challenged with endotoxin 2 h after administration. This suggests that these reagents can play a role in prophylaxis but not in therapy of sepsis. These experiments demonstrated that the PMB-IgG conjugate retains bound yet functional PMB as evidenced by its endotoxin-neutralizing activity both in vitro and in vivo. Further work is required to define the role that this or related conjugate compounds may play in the prophylaxis of endotoxin-mediated disease.
Oxfendazole Treatment for Cystic Hydatid Disease in Naturally Infected Animals
Authors: Blanton Ronald E. , Wachira Timothy M. , Zeyhle Eberhard E. , Njoroge Ernest M. , Magambo Japheth K. , Schantz Peter M.
Published: October 2018

Few chemotherapeutic agents are available for the medical management of hydatid disease caused by the parasite
Echinococcus granulosus
. In order to test the potential of oxfendazole for the treatment of infection with this parasite, nine infected goats and four sheep were given oxfendazole twice weekly at a dose of 30 mg/kg of body weight for 4 weeks and monitored by ultrasound for an additional 4 weeks. Efficacy was finally evaluated by postmortem examination, including determination of protoscolex viability and cyst wall histology. In treated animals, protoscolices were dead or absent in 97% of cysts from oxfendazole-treated animals compared to 28% of cysts from untreated control animals. On postmortem examination, 53% of cysts from treated animals were found to be grossly degenerate. A sample of those cysts that appeared potentially viable all demonstrated evidence of severe damage to the cyst wall. By light microscopy, cysts showed severe disorganization of the adventitial layer with invasion of inflammatory cells and in some cases frank necrosis with no apparent adventitial layer. The follow-up period for assessment of the drug’s ability to cause complete degeneration and resorption of cysts was relatively short. This study, however, indicates that oxfendazole is at least as effective as and is easier to administer than albendazole for the treatment of hydatid disease.