Showing papers on "Penicillin published in 1991"

Extremely High Incidence of Antibiotic Resistance in Clinical Isolates of Streptococcus pneumoniae in Hungary

Abstract: An epidemiologic survey of antibiotic resistance among pneumococcal isolates collected during 1988 and 1989 in Hungary indicated that as many as 58% of all isolates and 70% of isolates from children were resistant to penicillin. These figures surpass even the highest values reported thus far for Spain and South Africa for the same period. Almost or more than 70% of the penicillin-resistant isolates were also resistant to tetracycline, erythromycin, and cotrimoxazole and approximately 30% to chloramphenicol. Intravenous administration of ampicillin (30 mg/kg) did not interfere with the growth in the cerebrospinal fluid of three resistant strains introduced into the rabbit model of experimental meningitis. No resistant strain showed beta-lactamase activity. A representative highly resistant strain contained altered penicillin-binding proteins (low penicillin affinities and abnormal molecular sizes) and was also resistant to the lytic and killing effects of penicillin.

Antimicrobial Resistance of Streptococcus pneumoniae in the United States, 1979–1987

Abstract: The increasing number of Streptococcus pneumoniae isolates identified as relatively or fully resistant to penicillin or fully resistant to other antimicrobials in the United States supports the need to monitor for this resistance. Thus, 5459 S. pneumoniae isolates submitted to the Centers for Disease Control in 1979-1987 by 35 hospitals in a hospital-based pneumococcal surveillance system were evaluated. The MIC to penicillin or ampicillin was greater than or equal to 0.1 micrograms/ml for 274 (5%) isolates; 1 had an MIC of 4.0 micrograms/ml to penicillin. Seventeen (0.3%) were resistant to erythromycin (MIC, greater than or equal to 8 micrograms/ml), 157 (2.9%) were resistant to tetracycline (MIC, greater than or equal to 16 micrograms/ml), and 34 (0.6%) were resistant to sulfamethoxazole/trimethoprim (MIC, greater than or equal to 76 and 4 micrograms/ml). Isolates relatively resistant to penicillin represented 1.8% of isolates in 1979, 8% in 1982, and 3.6% in 1987. Sixty-five multiply resistant isolates were identified. Pneumococci from the southwestern United States (region 4) were more likely to be relatively resistant to penicillin. Using logistic regression analysis, serotypes 14 and 19A, isolates from region 4, and isolates from middle ear fluid were associated with penicillin resistance (P less than or equal to .008, chi 2. These data confirm that antimicrobial resistance among pneumococcal isolates remained at low levels in the United States through 1987.

A review of antibiotic resistance patterns of Streptococcus pneumoniae in Europe.

Abstract: Streptococcus pneumoniae no longer has predictable antibiotic susceptibility There are two areas of high prevalence of resistance (over 25%) to beta-lactam antibiotics in the South-West and North-East of Europe In Spain, a close relationship has been found between the yearly rate of aminopenicillin consumption and penicillin resistance High level resistance (MIC greater than or equal to 1 mg/L) has developed against a previous background of low level resistance The serotypes involved in penicillin resistance in Spain are widespread in other countries Macrolide resistance is high in France (over 15%) and is also increasing in other countries All these resistant isolates remain susceptible to the most recent fluoroquinolones, such as temafloxacin Prospective surveillance, more rational use of antibiotics and a diversification of antibiotic use in respiratory tract infections may serve to limit the threat of antibiotic resistance in S pneumoniae

Increasing resistance to beta-lactam antibiotics among clinical isolates of Enterococcus faecium: a 22-year review at one institution.

Abstract: To identify any change in the antibiotic resistance of Enterococcus faecium, we examined the antibiotic susceptibilities of clinical strains (n = 84) isolated at one institution during the 22 years since 1968. A significant increase in resistance to penicillin was observed during the study period: the MICs of penicillin for 50 and 90% of isolates tested were 16 and 64 micrograms/ml, respectively, from 1969 to 1988 (n = 48; geometric mean MIC, 14 micrograms/ml) , whereas they were 256 and 512 micrograms/ml, respectively, from 1989 to 1990 (n = 36; geometric mean MIC, 123 micrograms/ml) (P less than 0.001). A comparable increase in resistance to ampicillin was also noted (P less than 0.001). No strains produced detectable beta-lactamase. In contrast, susceptibilities to vancomycin, teicoplanin, and ciprofloxacin remained stable. High-level resistance to gentamicin was observed in none of 48 isolates from 1969 to 1988, but was present in 22 of 36 strains (61%) from 1989 to 1990 (P less than 0.001) and was significantly associated with resistance (MIC, greater than or equal to 128 micrograms/ml) to penicillin (P less than 0.001). To assess the potential evolution of antibiotic resistance in this species, clinical isolates (n = 24) were compared with strains isolated in 1968 from a human population in the Solomon Islands that was never exposed to antibiotics. Solomon Island isolates were significantly more susceptible than all clinical strains to penicillin, ampicillin, and vancomycin (P less than 0.001 for each), but they exhibited no differences in susceptibility to teicoplanin or ciprofloxacin. The penicillin-binding affinity of penicillin-binding protein 5 (PBP 5) in penicillin-resistant clinical strains (MIC, 512 micrograms/ml) was notably lower than that in strains with more typical susceptibilities, suggesting an alteration in this PBP as a possible mechanism for increased penicillin resistance. Solomon Island strains most susceptible to penicillin demonstrated a prominent PBP 5* and the absence of PBP 5. These changes in the antibiotic resistance of E. faecium emphasize the importance of identifying this species in patients with serious enterococcal infections and the necessity of assessing its susceptibility to both beta-lactams and aminoglycosides if effective therapy is to be identified.

A comparison of cephalosporins and penicillins in the treatment of group A beta-hemolytic streptococcal pharyngitis: a meta-analysis supporting the concept of microbial copathogenicity.

Abstract: Although penicillin has been the antibiotic of choice for therapy of Group A beta-hemolytic streptococcal pharyngitis for more than four decades, reports of bacteriologic and clinical treatment failures with penicillin have increased in recent years. We conducted a meta-analysis of 19 studies to examine whether oral cephalosporins were associated with lower failure rates than oral penicillin in the treatment of Group A beta-hemolytic streptococcal pharyngitis. The overall bacteriologic cure rate for penicillin was 84% (95% confidence interval (CI), 82%, 86%) compared with 92% (95% CI, 91%, 94%) among patients treated with cephalosporins (P less than 0.0001). The overall clinical cure rate in the penicillin groups was 89% (95% CI, 87%, 91%) compared with 95% (95% CI, 94%, 96%) in the cephalosporin group (P less than 0.001). There was no significant difference between the cephalosporins and the penicillins with respect to adverse events. There may be clinical circumstances in which treatment of Group A beta-hemolytic streptococcal pharyngitis with cephalosporins is indicated.

Localization of the pathway of the penicillin biosynthesis in Penicillium chrysogenum.

Abstract: The localization of the enzymes involved in penicillin biosynthesis in Penicillium chrysogenum hyphae has been studied by immunological detection methods in combination with electron microscopy and cell fractionation. The results suggest a complicated pathway involving different intracellular locations. The enzyme delta-(L-alpha-aminoadipyl)-L-cysteinyl-D-valine synthetase was found to be associated with membranes or small organelles. The next enzyme isopenicillin N-synthetase appeared to be a cytosolic enzyme. The enzyme which is involved in the last step of penicillin biosynthesis, acyltransferase, was located in organelles with a diameter of 200-800 nm. These organelles, most probably, are microbodies. A positive correlation was found between the capacity for penicillin production and the number of organelles per cell when comparing different P. chrysogenum strains.

Effects of combinations of beta-lactams, daptomycin, gentamicin, and glycopeptides against glycopeptide-resistant enterococci.

Abstract: Activities of combinations of beta-lactams, daptomycin, gentamicin, teicoplanin, and vancomycin against 11 clinical isolates of Enterococcus faecium highly resistant to glycopeptides, three plasmid-cured derivatives, eight E. faecalis and E. faecium transconjugants, and two susceptible recipient strains were tested. A marked synergy between penicillins or imipenem and glycopeptides against the glycopeptide-resistant strains but not against the glycopeptide-susceptible strains was observed by the double-disk agar diffusion assay. The synergy of combinations of amoxicillin, imipenem, penicillin G, or piperacillin with vancomycin or teicoplanin against resistant strains was confirmed by the checkerboard technique. The fractional inhibitory concentration indexes were generally below 0.25, except for one strain of E. faecium resistant to high levels of penicillin G. However, the combinations were not bactericidal as tested by time-killing experiments, and high concentrations (64 micrograms/ml) of amoxicillin, penicillin G, or piperacillin combined with 8 micrograms of vancomycin or teicoplanin per ml tended to be antagonistic. Addition of 4 micrograms of gentamicin per ml to these combinations enhanced their bactericidal effect, but they occasionally remained slightly less effective than beta-lactams associated with gentamicin. The combination of 10 micrograms of daptomycin per ml with gentamicin was bactericidal after 6 h against 11 glycopeptide-resistant strains.

Syphilis, neurosyphilis, penicillin, and AIDS.

Abstract: Early neurosyphilis, characterized by meningitis, cranial nerve abnormalities, and cerebrospinal accidents, was first described in patients with syphilis who received inadequate courses of arsphenamine. Although more effective, penicillin at conventional doses does not yield treponemacidal levels in the central nervous system and probably does not eradicate the infecting organisms, suggesting that it works synergistically with the host's immune response in preventing neurosyphilis. Neurosyphilis after penicillin therapy was almost unheard of in the United States until it began to appear in human immunodeficiency virus (HIV)-infected patients. Numerous cases of syphilitic meningitis, cranial nerve abnormalities, and strokes have been reported in the past decade; about one-half of reported patients had received penicillin therapy, often within the previous 6 months. Thus, more intensive diagnostic evaluation, perhaps including routine cerebrospinal fluid analysis, more intensive therapy, for example with at least three doses of benzathine penicillin, and far more rigorous follow-up are indicated in HIV-infected subjects with syphilis. Since the efficacy of conventional therapy is now uncertain, novel approaches to treatment deserve systematic evaluation.

Antibiotic management of outpatients with endocarditis due to penicillin-susceptible streptococci.

Abstract: Thirty patients with endocarditis caused by penicillin-susceptible streptococci were enrolled in one of two groups in this study. Fifteen patients received ceftriaxone (2 g once daily) for 4 weeks; the other 15 received the same dosage of ceftriaxone for 2 weeks and then received oral amoxicillin (1 g four times a day) for 2 weeks. For the 27 patients treated predominantly as outpatients, 380 days of hospitalization were avoided. Clinical cure was achieved for all patients in both groups. We conclude that ceftriaxone, alone or followed by a course of amoxicillin, is an efficacious mode of treatment for infective endocarditis caused by penicillin-susceptible streptococci. Treatment with these agents can be administered predominantly on an outpatient basis.

Synergistic killing of vancomycin-resistant enterococci of classes A, B, and C by combinations of vancomycin, penicillin, and gentamicin.

Abstract: Using both high and low inocula for time-kill curves, we examined the antibiotic killing of clinical isolates of glycopeptide-resistant enterococci (Enterococcus faecium, E. faecalis, and E. gallinarum) belonging to phenotypic resistance classes A, B, and C. None were resistant to high levels (greater than 500 mg/liter) of gentamicin. Vancomycin-penicillin-gentamicin resulted in 2 or more logs of killing above that of the most effective two-antibiotic combination for all strains except two of three E. gallinarum (VanC) strains and a constitutive mutant of a VanB strain. This strategy may be useful clinically.

pH regulation of penicillin production in Aspergillus nidulans.

Abstract: As shown by both bioassay and high-performance liquid chromatographic (HPLC) analysis, penicillin G production by Aspergillus nidulans is subject to regulation by the pH of the growth medium. Penicillin titres were highest at alkaline pH and in strains carrying mutations in the regulatory gene pacC which mimics the effects of growth at alkaline pH. They were lowest at acid pH and in strains carrying mutations in the palA, palB, palC, palE or palF genes which mimic the effects of growth at acid pH.

Penicillin resensitization among hospitalized patients

Abstract: The purpose of this study was to determine the frequency of resensitization to penicillin after oral or intravenous treatment with β-lactam antibiotics in hospitalized patients with histories of penicillin allergy. Seventeen adults (aged 24 to 76 years) and one child (aged 10 years) were treated intravenously and/or orally with β-lactam antibiotics after negative skin tests were obtained with benzylpenicilloyl polylysine, potassium penicillin G, and alkaline hydrolysis products of penicillin G as minor determinant mixture. Repeat skin testing was performed 1 to 12 months after the therapy. Three patients (16%) became skin test positive after the treatment. Two patients reacted to potassium penicillin G alone, and the other patient reacted to benzylpenicilloyl polylysine and minor determinant mixture. These three patients were among the 15 patients who were treated with intravenous antibiotics. This study reveals a high percentage of skin test conversion after intravenously administered penicillin therapy and confirms the present practice of advising patients with a history of penicillin allergy who have successfully completed penicillin treatment to have a repeat skin test before future exposure to β-lactam antibiotics.

Distribution, antibiotic susceptibility and tolerance of bacterial isolates in culture-positive cases of endocarditis in The Netherlands.

Abstract: During a two-year period data were collected nationwide in The Netherlands on 438 episodes of bacterial endocarditis (BE) in 432 patients. Of the strains isolated in these patients 419 were available for analysis. Of these, 326 were isolated in native valve endocarditis (NVE) and 93 in prosthetic valve endocarditis (PVE). Viridans streptococci, staphylococci and enterococci together constituted 87 % of the isolates. More than 46 % of the viridans streptococci consisted ofStreptococcus sanguis. Enterococus faecalis andStaphylococcus aureus were the predominant species in the late form of PVE. The majority of the viridans streptococci and haemolytic streptococci were highly susceptible to penicillin. Five of 35 strains of coagulase negative staphylococci were resistant to methicillin. Eleven percent of a random sample of the streptococci collected were tolerant to penicillin. After repeated exposure to a concentration gradient of an appropriate β-lactam antibiotic, this figure increased to 49 %. Of the staphylococci, 5–6 % of the strains were tolerant before induction and 16–20 % after induction. Of theEnterococcus strains (n=40), 12.5 % showed high-level resistance to one or more aminoglycoside.

Allergy to penicillin: fable or fact?

Abstract: OBJECTIVE--To assess whether, on the basis of one blood test, penicillin allergy might be excluded sufficiently for general practitioners to give oral penicillin to patients claiming a history of penicillin allergy. DESIGN--Prospective study of patients referred by general practitioners. SETTING--Outpatient allergy clinic in a district general hospital. PATIENTS--175 referred patients who gave a history of immediate type reaction to penicillin, of whom 144 attended as requested and 132 completed the investigations. MAIN OUTCOME MEASURES--History and examination, serum radioallergosorbent test to phenoxymethylpenicillin and benzylpenicillin, and oral challenge with penicillin. RESULTS--Of 132 patients, four were confirmed to have penicillin allergy by the radioallergosorbent test and 128 had an oral penicillin challenge without ill effect. CONCLUSIONS--Most patients who gave a history of penicillin allergy are not so allergic, and their actual allergic state should be substantiated whenever feasible. For patients reporting minor or vague reactions negative findings with a radioallergosorbent test to phenoxymethylpenicillin and benzylpenicillin provide sufficient evidence to give oral penicillin safely.

Role of the beta-lactamase of Campylobacter jejuni in resistance to beta-lactam agents.

Abstract: We studied the role of the beta-lactamase of Campylobacter jejuni in resistance to beta-lactam agents. beta-Lactamase-positive strains were more resistant than beta-lactamase-negative strains to amoxicillin, ampicillin, and ticarcillin (P less than 0.05). With penicillin G, piperacillin, imipenem, and six cephalosporins, the susceptibility levels were similar for both beta-lactamase-positive and -negative strains. By using spectrophotometric and microbiological assays, the beta-lactamase from three strains hydrolyzed ampicillin, amoxicillin, penicillin G, cloxacillin, and, partially, cephalothin. Ticarcillin and piperacillin were partially hydrolyzed in the microbiological assay. There was no activity against five other cephalosporins or imipenem. Isoelectric focusing of the enzyme showed a pI of 8.8. Tazobactam was the best inhibitor of the enzyme, followed by clavulanic acid, sulbactam, and cefoxitin, while EDTA and p-chloromercuribenzoate had no activity. All beta-lactamase-positive strains became susceptible to amoxicillin and ampicillin with 1 micrograms of clavulanic acid per ml. With the same inhibitor, there was a reduced but significant effect for ticarcillin but no effect for penicillin G or piperacillin. Sulbactam had no effect and tazobactam was effective only at 2 micrograms/ml on amoxicillin and ampicillin. The beta-lactamase of C. jejuni seems to be a penicillinase with a role in resistance for only amoxicillin, ampicillin, and ticarcillin.

β-Lactam Resistance Mechanisms of Methicillin-Resistant Staphylococcus aureus

Abstract: In vitro and in vivo activity of amoxicillin and penicillin G alone or combined with a penicillinase inhibitor (clavulanate) were tested against five isogenic pairs of methicillin-resistant Staphylococcus aureus (MRSA) producing or not producing penicillinase. Loss of the penicillinase plasmid caused an eight times or greater reduction in the MICs of amoxicillin and penicillin G (from greater than or equal to 64 to 8 micrograms/ml), but not of the penicillinase-resistant drugs methicillin and cloxacillin (greater than or equal to 64 micrograms/ml). This difference in antibacterial effectiveness correlated with a more than 10 times greater penicillin-binding protein 2a affinity of amoxicillin and penicillin G than of methicillin and a greater than or equal to 90% successful amoxicillin treatment of experimental endocarditis due to penicillinase-negative MRSA compared with cloxacillin, which was totally ineffective (P less than .001). Amoxicillin was also effective against penicillinase-producing parent MRSA, provided it was combined with clavulanate. Penicillinase-sensitive beta-lactam antibiotics plus penicillinase inhibitors might offer a rational alternative treatment for MRSA infections.

Triple combination penicillin-vancomycin-gentamicin for experimental endocarditis caused by a highly penicillin-and glycopeptide-resistant isolate of Enterococcus faecium.

Abstract: An in vitro bacteriostatic synergy between beta-lactam and glycopeptide antibiotics has been recently described against isolates of Enterococcus faecium moderately resistant to penicillin and highly resistant to vancomycin. The relevance of this synergy in a rabbit endocarditis model was evaluated. Penicillin was tested at low- (LoD) and high-dose (HiD) regimens, alone or combined with vancomycin and/or gentamicin. Compared with controls, after a 5-day treatment: LoD penicillin, vancomycin, gentamicin, LoD penicillin plus gentamicin or vancomycin, and vancomycin-gentamicin were not effective; LoD penicillin-vancomycin caused a small reduction of bacterial titers in vegetations that was strongly enhanced by adding gentamicin; HiD penicillin-gentamicin, the most effective regimen, was not significantly better than LoD penicillin-vancomycin-gentamicin. These results suggest that the relative in vivo inefficacy of penicillin-vancomycin might be related to the fact that this combination was poorly bactericidal, and the triple combination of LoD penicillin-vancomycin-gentamicin or the combination of HiD penicillin-gentamicin should be considered in the treatment of serious infections due to beta-lactam- and glycopeptide-resistant enterococci.

The Enterococcus hirae R40 penicillin-binding protein 5 and the methicillin-resistant Staphylococcus aureus penicillin-binding protein 2′ are similar

Abstract: The penicillin-resistant Enterococcus hirae R40 has a typical profile of membrane-bound penicillin-binding proteins (PBPs) except that the 71 kDa PBP5 of low penicillin affinity represents about 50% of all the PBPs present. Water-soluble tryptic-digest peptides were selectively produced from PBP5, their N-terminal regions were sequenced and synthetic oligonucleotides were used as primers to generate a 476 bp DNA fragment by polymerase chain reaction. On the basis of these data, the PBP5-encoding gene was cloned in Escherichia coli by using pBR322 as vector. The gene, included in a 7.1 kb insert, had the information for a 678-amino acid-residue protein. PBP5 shows similarity, in the primary structure, with the high-molecular-mass PBPs of class B. In particular, amino acid alignment of the enterococcal PBP5 and the methicillin-resistant staphylococcal PBP2' generates scores that are 30, for the N-terminal domains, and 53, for the C-terminal domains, standard deviations above that expected for a run of 20 randomized pairs of proteins having the same amino acid compositions as the two proteins under consideration.

The Jarisch-Herxheimer Reaction in Leptospirosis: Possible Pathogenesis and Review

Abstract: The importance of treating leptospirosis with penicillin is emphasized by two case reports and a review documenting the occurrence of the Jarisch-Herxheimer reaction (JHR) in patients with this bacterial infection. The JHR is significant both as a cause of morbidity and mortality and as an indication of the therapeutic efficacy of penicillin. The possible etiology of the JHR is discussed, and comparisons with the changes occurring in septic shock are made; a study of either condition facilitates the understanding of the other. Tumor necrosis factor is hypothesized to play a key role in both. Current treatment of the JHR consists of general clinical support. Specific measures such as oxpentifylline therapy may play a role in the future.

Immediate vs. delayed treatment of group A beta-hemolytic streptococcal pharyngitis with penicillin V.

Abstract: Three hundred six children with probable Group A beta-hemolytic streptococcal pharyngitis were enrolled in a randomized double blind trial to compare the effects of immediate vs. delayed treatment with oral penicillin V. Among the 229 culture-positive patients, 111 were randomly assigned to receive penicillin V immediately and 118 to receive a placebo for 48 to 52 hours followed by penicillin V. Patients were evaluated clinically for 48 to 52 hours following initiation of treatment. The Streptozyme test was used to measure acute to convalescent antibody titer. Both regimens resulted in a greater than 92% cure rate. Early treatment was associated with significantly fewer and milder signs and symptoms on Day 3 and a significantly lower rise in the antibody titer. On the other hand we found 8 (7%) relapses and 18 (16%) early and 14 (13%) late recurrences in this group; all were significantly higher than the corresponding numbers of 2 (2%), 6 (5%) and 4 (3%), respectively, in the late treatment group. This study shows the beneficial effect of early treatment with penicillin V on the clinical course of Group A beta-hemolytic streptococcal pharyngitis. This study also shows that delayed penicillin treatment may be associated with a lower incidence of subsequent Group A beta-hemolytic streptococcal pharyngitis.

Endocarditis Due to Corynebacterium pseudodiphtheriticum: Five Case Reports, Review, and Antibiotic Susceptibilities of Nine Strains

Abstract: Five cases of endocarditis due to Corynebacterium pseudodiphtheriticum are described. Two patients died, two patients with prosthetic valve endocarditis were successfully treated with antibiotics and valve replacement, and one patient with native valve endocarditis was successfully treated with penicillin alone. We also review 12 previously reported cases of C. pseudodiphtheriticum endocarditis. In vitro susceptibilities to 15 antibiotics were determined for nine isolates. The minimum inhibitory concentrations (MICs) of penicillin, amoxicillin, cefamandole, cephalexin, and rifampicin were all less than or equal to 0.12 mg/L. The MICs of vancomycin and ciprofloxacin for all strains were less than or equal to 0.5 mg/L. Tobramycin was the most active aminoglycoside, with MICs for all strains that were less than or equal to 0.12 mg/L. On the basis of in vitro data and the results of previous reports, penicillin alone or in combination with an aminoglycoside should achieve bacteriologic cure. Vancomycin should be used in patients who are allergic to penicillin.

The antibiotic sensitivity patterns of Bacillus anthracis isolated from the Kruger National Park.

Abstract: Forty-four isolates of Bacillus anthracis made from carcasses and soil in different localities of an endemic anthrax area in the Kruger National Park, South Africa, were tested by standard disc diffusion for their susceptibility to 18 different antibiotics. These were ampicillin, penicillin G, sulphatriad, streptomycin, clindamycin, gentamicin, fusidic acid, trimethoprim, sulphamethoxazole, chloramphenicol, erythromycin, methicillin, tetracycline (2 different concentrations), novobiocin, cefotaxime, netilmicin, cefamandole and cefoxitin. All the isolates were susceptible to ampicillin, streptomycin, chloramphenicol, erythromycin, tetracycline, methicillin and netilmicin. More than 90% of the isolates were sensitive to clindamycin, gentamicin and cefoxitin, whereas only 84.1% of the isolates were sensitive to penicillin G, 86.4% to novobiocin and 68.18% to cefamandole. Complete resistance in 100% of the isolates was encountered with trimethoprim and sulphamethoxazole, with 95.45% for sulphatriad. Moderate sensitivity occurred with penicillin G (15.9% of the isolates), clindamycin (6.8%), novobiocin (13.6%), fusidic acid (84.1%), cefotaxime (100%), cefamandole (31.8%) and cefoxitin (6.8%). The relevance of the findings to the therapeutic uses of different types of antibiotic in human clinical cases referred to in the literature is discussed.

Sensitization to aztreonam and cross-reactivity with other beta-lactam antibiotics in high-risk patients with cystic fibrosis.

Abstract: The immunogenicity, allergenicity, and cross-reactivity of aztreonam were investigated in 21 patients with cystic fibrosis (CF) (aged 5 to 39 years) with well-documented histories of allergic systemic reactions (SRs) to penicillin and/or cephalosporin antipseudomonal beta-lactam antibiotics (BLAs) Skin tests (STs) with penicilloyl-polylysine (PPL), penicillin minor determinant mixture, and antipseudomonal BLA were positive in 19 patients (90%) The BLA causing the most recent allergic reaction, minor determinant mixture, or PPL, was positive in 89%, 53%, and 32% of ST-positive patients, respectively Serum PPL-specific IgE antibodies were not detectable, although PPL-specific IgG antibodies were found in 64% of patients tested STs to aztreonam reagents were performed and were initially negative in 20 patients One patient was ST positive to the polylysine conjugate of hydrolyzed aztreonam (SQ 27629), despite no prior exposure to aztreonam, and was not treated Of 20 patients treated with aztreonam, four were demonstrated to be sensitized by exposure (one had an SR during initial treatment course, two had SRs on reexposure, and one patient was asymptomatic after intravenous desensitization) by positive aztreonam reagent skin responses on repeat testing Aztreonyl-specific IgE and IgG serum antibodies were not detected in any patients, including patients with allergic reactions to aztreonam Thus, aztreonam is generally well tolerated in high-risk patients with CF allergic to other BLAs and appears to have reduced immunogenicity by serologic testing However, caution should be exercised with aztreonam in BLA-allergic patients with CF in light of 5% preexisting ST cross-reactivity and 20% sensitization rates found in this study

The microbiology of peritonsillar sepsis.

Abstract: Pus obtained by needle aspiration of 91 peritonsillar abscesses was examined microbiologically. A positive culture was obtained in 55 patients (60 per cent). Sixty-four bacteriological isolates were grown. Forty patients had a pure growth of a single organism, of which 21 (53 per cent) were beta Haemolytic streptococci. Pure growths of Staphylococcus aureus were found in only three patients. Fifteen patients had mixed organisms, including anaerobes, in their pus and the resistance to penicillin was low. Only the bacteroides species were generally penicillin resistant. The vast majority of patients made a good recovery following needle drainage of the abscess and treatment with parenteral penicillin. The patients with a mixture of penicillin sensitive and penicillin resistant organisms also made a good clinical recovery following needle drainage and administration of parenteral penicillin. The relevance of these findings in the pathogenesis and management of peritonsillar sepsis is discussed.