Our library of drug research abstracts drawn from the medical literature is updated on a regular schedule, and you can be assured that new penicillin research articles will be listed here shortly after becoming available to us.
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Medical research on penicillin
Curr Microbiol. 2008 Sep 25;
Miyazaki H, Horii T, Nagura O, Suda T, Chida K, Nakamura H
A higher inoculum size of beta-lactamase-positive Haemophilus influenzae is reported to increase minimum inhibitory concentrations (MICs) for beta-lactams. However, the effect of inoculum size of beta-lactamase-negative, ampicillin-resistant H. influenzae (BLNAR) on MICs for carbapenems has not been investigated. This study evaluated the effect of inoculum size on MICs for carbapenems and other beta-lactams in nine clinical isolates of BLNAR. The MICs were determined by both the standard method described by the Clinical and Laboratory Standards Institute (final inoculum size of 5 x 10(5) colony-forming units [CFU]/ml) and a modified method (final inoculum size of 5 x 10(6) CFU/ml) using viable cell counts. The findings showed that the higher inoculum size increased MICs for imipenem, meropenem, panipenem, biapenem, ampicillin, ceftazidime, and ceftriaxone. The inoculum effect (4 log(2) dilution or a greater increase in the MIC) with imipenem, meropenem, panipenem, and biapenem was found in three, five, two, and two isolates, respectively. The magnitude of the inoculum effect for panipenem significantly increased with the levels of MICs, but correlation between them for the others was not statistically significant. The mutations of penicillin-binding protein genes had little relevance to the reduced susceptibility to carbapenems or to the magnitude of the inoculum effect. These results suggest that MIC determination using turbidity can produce interpretive errors in the antimicrobial susceptibility testing of BLNAR for carbapenems because of their inoculum effect. Thus, accurate adjustment of inoculum size, such as viable cell count, is helpful for confirming the true MICs when the isolates are interpreted as "resistant" by turbidity-based MIC determination.
[Syphilis in 2008: practical aspects and controversies]
Rev Med Suisse. 2008 Aug 27; 4(168): 1823-7
Frippiat F, Giot JB, Chandrikakumari K, Léonard P, Meuris C, Moutschen M
Rising incidence rate of syphilis is observed in economically advanced countries, particularly among homosexual men and subpopulation with low socioeconomic status. The various clinical presentations are divided into early and late stages, including neurosyphilis. The latter can occur during any stage of the disease, leading to the question "when to perform lumbar puncture", particularly in HIV positive patients. Penicillin continues to be the first-line therapy for all stages of syphilis. An alternative treatment should be considered as an exemption, after advice from a specialist. All patients require prolonged clinical and serological follow-up after treatment to rule out relapse or re-infection. The diagnosis of syphilis is an opportunity to search and treat other sexually transmitted diseases in patients and their sexual partner(s).
Rev Inst Med Trop Sao Paulo. 2008 Aug; 50(4): 203-207
Araújo AM, Oliveira IC, Mattos MC, Benchetrit LC
The minimum inhibitory concentration and post-antibiotic effects of an antimicrobial agent are parameters to be taken into consideration when determining its dosage schedules. The in vitro post-antibiotic effects on cell surface hydrophobicity and bacterial adherence were examined in one strain of group B streptococci. Exposure of the microorganism for 2 h at 37 degrees C to 1 x MIC of penicillin induced a PAE of 1.1 h. The cell surface charge of the Streptococcus was altered significantly during the post-antibiotic phase as shown by its ability to bind to xylene: hydrophobicity was decreased. Bacterial adherence to human buccal epithelial cells was also reduced. The results of the present investigation indicate that studies designed to determine therapeutic regimens should evaluate the clinical significance of aspects of bacterial physiology during the post-antibiotic period.
Arq Neuropsiquiatr. 2008 Sep; 66(3A): 509-15
de Oliveira Rossoni AM, Dalla Costa LM, Berto DB, Farah SS, Gelain M, de Cunto Brandileone MC, Ramos VH, de Almeida SM
The main objectives of this study are to evaluate the resistance rates of Streptococcus pneumonia to penicillin G, ceftriaxone and vancomycin in patients with meningitis; to analyze possible risk factors to the antimicrobian resistance; to describe the serotypes detected and to suggest an initial empirical treatment for meningitis. The sensitiveness and serotypes of all isolated S. pneumoniae of patients with acute bacterial meningitis received by the Paraná State Central Laboratory from April 2001 to august 2002 have been evaluated. One hundred S. pneumoniae have been isolated, of which 15% were resistant to penicillin, 1% to cephalosporin and 0% to vancomycin. The serotypes most found were 14 (19%), 3 and 23F (10% each). When only the resistant serotypes were analyzed, the most prevalent was the 14 with 44%. The risk factors found in relation to the S. pneumoniae resistance were: age under one year old (p=0.01) and previous use of antibiotic (p=0.046). The resistance rates found, which were moderate to penicillin, low to cephalosporin and neutral to vancomycin, suggest the isolated use of a 3rd generation cephalosporin as an initial empirical therapy for the treatment of acute bacterial meningitis with a communitarian background.
Ann Pharmacother. 2008 Sep 23;
Therriault BL, Daniels LM, Carter YL, Raasch RH
OBJECTIVE: To describe a case of severe sepsis, cavitary pneumonia, and pyomyositis caused by Arcanobacterium haemolyticum. CASE SUMMARY: An 18-year-old male with a medical history significant for mild asthma presented to the emergency department complaining of a 7-day history of fever, diffuse myalgias, nausea, vomiting, diarrhea, and pain in his right upper quadrant, right shoulder, and left thigh. Cultures of blood, bronchoalveolar fluid, and surface and surgical swabs from the patient's left lower extremity grew A. haemolyticum. The patient was successfully treated with intravenous penicillin G 4 million units every 4 hours and azithromycin 500 mg once daily for 14 days. Within 36 hours after initiation of focused therapy, he became afebrile, pain decreased, and pulmonary symptoms abated. Oral azithromycin 500 mg/day for an additional 3 weeks was prescribed on discharge, and the patient showed no relapse at 2-month follow-up. DISCUSSION: A. haemolyticum is a weakly acid-fast, branching gram-positive bacillus most commonly implicated in pharyngitis in healthy adolescents and skin and soft-tissue infections in older, immunocompromised patients. Systemic infections are rarely reported in the literature. This organism remains susceptible to most classes of antimicrobials, including penicillins, cephalosporins, carbapenems, macrolides, tetracyclines, clindamycin, and vancomycin. Routine resistance has been reported only with trimethoprim/sulfamethoxazole. CONCLUSIONS: To our knowledge, there are no published case reports of severe sepsis caused by A. haemolyticum. While treatment options are numerous, we recommend the use of intravenous penicillin or a cephalosporin as first-line pharmacologic management of deep-seated infections caused by this rare organism.
Zoonoses Public Health. 2008 Oct; 55(8-10): 507-13
Freshwater A
Approximately four to five million animal bite wounds are reported in the USA each year. Domestic companion animals inflict the majority of these wounds. Although canine bites far outnumber feline bites, unlike the dog, the cat's bite is worse than its bark; 20-80% of all cat bites will become infected, compared with only 3-18% of dog bite wounds. Pasteurella multocida is the most commonly cultured bacterium from infected cat bite wounds. Anyone seeking medical attention for a cat-inflicted bite wound is given prophylactic/empiric penicillin or a derivative to prevent Pasteurella infection (provided they are not allergic to penicillins). In an effort to establish a carriage rate of P. multocida in the domestic feline, bacterial samples from the gingival margins of domestic northern Ohio cats (n = 409) were cultured. Isolates were tested for antibiotic sensitivity as prophylactic/empiric use of penicillin and its derivatives could potentially give rise to antibiotic resistance in P. multocida. The high carriage rate ( approximately 90%) of P. multocida observed was found to be independent of physiological and behavioural variables including age, breed, food type, gingival scale, lifestyle and sex. High antibiotic susceptibility percentages were observed for benzylpenicillin, amoxicillin-clavulanate, cefazolin, and azithromycin (100%, 100%, 98.37% and 94.02%, respectively) in P. multocida isolates. The high prevalence of P. multocida in the feline oral cavity indicates that prophylactic/empiric antibiotic therapy is still an appropriate response to cat bite wounds. Additionally, the susceptibility of P. multocida to penicillin and its derivatives indicates that they remain reliable choices for preventing and treating P. multocida infections.
Clinical pharmacokinetics of penicillins in the neonate: a review of the literature.
Eur J Clin Pharmacol. 2008 Sep 23;
Pacifici GM, Labatia J, Mulla H, Choonara I
BACKGROUND: Sepsis is common in neonates and a major cause of morbidity and mortality. Sixty percent of preterm neonates receive at least one antibiotic during the first week of life, with penicillins being the most frequently administered antibiotics. The clearance (Cl), serum half-life (t((1/2))) and volume of distribution (Vd) of penicillins are different in the neonate than in the adult. As such, the pharmacokinetics of penicillins need be studied in neonates in order to optimise therapy in this age class with these drugs. OBJECTIVES: The aim of this study was to review the published data on the pharmacokinetics of penicillins in the neonate in order to provide a critical analysis of the literature and, consequently, a useful tool in the hands of the physician. METHODS: The bibliographic search was performed electronically using the PubMed and EMBASE databases as search engines. An initial search was performed with the keywords "pharmacokinetics", "penicillins" and "neonates". Secondly, other searches were performed using the keywords "pharmacokinetics" and "neonates", followed by the name of a single antibiotic. The search included articles up to 2007. RESULTS: There have been few pharmacokinetic studies on the use of penicillins in neonates. The results from those few studies that have been carried out suggest that the Cl is reduced and t((1/2)) prolonged in the neonate as compared with the more mature infant. There is little variation in Vd during the first week of life. In the premature neonate, Cl is reduced compared to the full-term infant. As postnatal age proceeds, the Cl of penicillins increases. CONCLUSIONS: More pharmacokinetic studies are required to provide a sound scientific basis for planning a dosage regimen with penicillins in the neonate.
Antimicrob Agents Chemother. 2008 Sep 22;
Nagano N, Nagano Y, Kimura K, Tamai K, Yanagisawa H, Arakawa Y
Recent emergence of group B streptococcal isolates exhibiting increased MICs of penicillins at our medical center and other hospitals in Japan prompted a comparative analysis of their PBPs with those from penicillin-susceptible strains comprising four neonatal invasive strains isolated during 1976 to 1988 and two recent isolates. The PBP sequences of penicillin-susceptible strains were highly conserved irrespective of their isolation dates. Of six strains with reduced susceptibility to penicillin (penicillin MICs, 0.25-0.5 microg/ml), strains R1, R2, R5 and R6 shared a unique set of five amino acid substitutions including V405A adjacent to the 402SSN404 motif in PBP2X, and one in PBP2B. The remaining two strains, R3 and R4, shared several substitutions including Q557E adjacent to the 552KSG554 motif in the PBP2X in addition to the substitutions in PBP2B, which are commonly found among penicillin-insusceptible strains. Strains R7 and R8 with a penicillin MIC of 1 microg/ml shared a unique set of eight amino acid substitutions, two in PBP2X, two in PBP2B including G613R adjacent to 614KTG616 motif, three in PBP1A, and one in PBP2A, and the substitution Q557E in PBP2X was common to R3 and R4. Binding of BOCILLIN FL was reduced or not detected in some PBPs including PBP2X of penicillin-insusceptible strains, but no significant reduction of pbp2x transcription was found in such strains. Phylogenic comparative analyses imply the absence of epidemic penicillin-insusceptible strains, and several genetic lineages of penicillin-insusceptible strains have been independently emerging through accumulating mutations in their pbp genes, especially in pbp2x.
Community infections caused by extended-spectrum beta-lactamase-producing Escherichia coli.
Arch Intern Med. 2008 Sep 22; 168(17): 1897-902
Rodríguez-Baño J, Alcalá JC, Cisneros JM, Grill F, Oliver A, Horcajada JP, Tórtola T, Mirelis B, Navarro G, Cuenca M, Esteve M, Peña C, Llanos AC, Cantón R, Pascual A
BACKGROUND: Extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli is an increasingly important group of community pathogens worldwide. These organisms are frequently resistant to many of the antimicrobial agents usually recommended for the treatment of infections caused by E coli, such as penicillins, cephalosporins, fluoroquinolones, and trimethoprim-sulfamethoxazole. Data concerning risk factors, clinical features, and therapeutic options for such infections are scarce. METHODS: A case-control study was performed to investigate the risk factors for all types of community-acquired infections caused by ESBL-producing E coli in 11 Spanish hospitals from February 2002 to May 2003. Controls were randomly chosen from among outpatients with a clinical sample not yielding ESBL-producing E coli. The clinical features of these infections were investigated in the case patients. The efficacy of fosfomycin tromethamine and amoxicillin-clavulanate potassium was observationally studied in patients with cystitis. RESULTS: A total of 122 cases were included. Risk factors selected by multivariate analysis included the following: age older than 60 years; female sex; diabetes mellitus; recurrent urinary tract infections (UTIs); previous invasive procedures of the urinary tract; follow-up in outpatient clinic; and previous receipt of aminopenicillins, cephalosporins, and fluoroquinolones. Urinary tract infections accounted for 93% of the cases; 6% of the patients were bacteremic and 10% needed hospitalization. The cure rate of patients with cystitis was 93% with fosfomycin therapy (all isolates were susceptible); among patients treated with amoxicillin-clavulanate, cure rates were 93% for those with susceptible isolates (minimum inhibitory concentration < or =8 microg/mL) and 56% for those with intermediate or resistant isolates (minimum inhibitory concentration > or =16 microg/mL) (P = .02). CONCLUSIONS: In predisposed patients, ESBL-producing E coli is a notable cause of community-acquired infection, and particularly UTI. Fosfomycin and amoxicillin-clavulanate appear to be effective for cystitis caused by susceptible isolates.
Vet Microbiol. 2008 Aug 5;
Bandara AB, Schurig GG, Sriranganathan N, Prasad R, Boyle SM
The penicillin-binding proteins (PBPs) are enzymes that regulate the assembly of the peptidoglycan layer of the bacterial cell wall. The genome of Brucella melitensis strain 16M possesses seven pbp genes: three in pbp-1 family (designated as 1A, 1B, and 1C); one in pbp-2 family; and three in pbp-6 family (designated as 6A, 6B, and 6C). We investigated the importance of pbp-1 and pbp-2 genes to viability, cell morphology and infectivity of B. melitensis. A recombinant B. melitensis strain (designated 16MDeltapbp1C) was generated by disrupting the pbp-1C of strain 16M by allelic exchange. This strain produced nearly 20% smaller colonies on trypticase soy agar plates, and grew slower in trypticase soy broth compared to the strain 16M. Electron microscopy revealed that strain 16M exhibited native cocco-bacillus morphology, while 16MDeltapbp1C possessed a spherical morphology. Strain 16MDeltapbp1C did not differ from strain 16M in terms of recovery from infected mouse macrophage cell line J774.1, or recovery from spleens of infected BALB/c mice, suggesting that pbp-1C is dispensable for intracellular persistence of B. melitensis. Expression of mRNA of fixR, the gene downstream of pbp-1C was similar between the strains 16M and 16MDeltapbp1C suggesting that disruption of pbp-1C did not induce any polar effects. Multiple attempts to mutate pbp-1A, pbp-1B, or pbp-2 genes failed, most probably because these genes are indispensable for viability of B. melitensis. Our findings suggest that pbp-1C regulates in vitro growth and cell morphology, whereas pbp-1A, pbp-1B, and pbp-2 are essential for viability of B. melitensis.