Serotype distribution and antimicrobial susceptibility of Streptococcus pneumoniae strains isolated in Japan after introduction of the routine immunization program.

Pneumococcal vaccines have reduced the incidences of Streptococcus pneumoniae infections among children and adults, but a relative increase in the prevalence of non-vaccine serotypes has been reported. To follow the changing epidemiology of pneumococcal diseases, capsular serotyping and antimicrobial susceptibility testing was performed on 534 pneumococcal isolates obtained from a hospital in Japan after routine immunization was launched, between October 2014 and May 2016. Serotype distributions and antimicrobial susceptibilities were evaluated among the total patient population, and were compared by age and sample groups and by serotype group, respectively. Serotypes targeted by the 13-valent pneumococcal conjugate vaccine (PCV13) were identified in 14.6%, 44.5%, and 40.2% of the samples from the <5, 5-64, and ≥65 year age groups, respectively. The 23-valent pneumococcal polysaccharide vaccine serotypes (PPSV23) were identified in 42.4%, 68.2%, and 63.1% of the samples, respectively; whereas non-PCV13 serotypes or non-PPSV serotypes (NVT) comprised 46.8% of all isolates. Among NVT, strain 35B was the most frequently isolated, followed by 15A, particularly in sputum samples collected from children <5 years old. Meanwhile, serotype 3, which is targeted by the PCV13 and PPSV23, was the most prevalent among patients aged ≥65 and 5-64 years. Antimicrobial susceptibility testing revealed that 88.9% and 81.0% of serotype 35B was non-susceptible to penicillin and meropenem, respectively, and 89.4% of 15A was non-susceptible to penicillin. Our data suggest rapid effects of pneumococcal vaccines and progression of serotype replacement. Besides invasive potential, the increased prevalence of non-vaccine serotypes with highly non-susceptible to penicillin was a concern. Continuous monitoring of pneumococcal serotypes and antimicrobial susceptibility is necessary for developing optimal preventive strategies.

Antimicrobial resistance patterns of Pseudomonas aeruginosa in tertiary care hospitals of Makkah and Jeddah.

BACKGROUND: The clinical significance of Pseudomonas aeruginosa has greatly increased due to its ability to rapidly develop resistance to major groups of antibiotics. OBJECTIVES: Our objective was to determine the pattern of antimicrobial resistance of P aeruginosa. DESIGN: Prospective, descriptive study. SETTING: Four tertiary care hospitals in Makkah and Jeddah. METHODS: Clinical isolates of P aeruginosa were processed following standard microbiological procedures. A Microscan Walk Away system was used for the identification and antibiotic susceptibility of P aeruginosa isolates. MAIN OUTCOME MEASURES: Percentage of resistance of P aeruginosa to antibiotics. RESULTS: The overall drug resistance among 121 strains of P aeruginosa was low to moderate to commonly used anti-pseudomonal drugs (4.9% to 30.6%). Significantly less resistance was exhibited by piperacillin tazobactam (4.9%; P < .05) and meropenem showed significantly high resistance (30.6%; P < .05) as compared to other antibiotics, followed by ticarcillin (22.3%) and imipenem (19%), irrespective of the site of infection. The antibiotics with < 10% resistance were cefepime (8.3%), amikacin (7.4%) and piperacillin-tazobactam, which showed lowest resistance (4.9%). Although, data varied between hospitals, meropenem and ticarcillin had the highest drug resistance in all hospitals. Multidrug resistance was 10.7%. CONCLUSION: Low-to-moderate rates of drug resistance among P aeruginosa isolates were observed. Meropenem resistance was high irrespective of the site of infection. This pattern of resistance indicates probable overuse of broad-spectrum antibiotics like carbapenems. Overuse needs to be addressed by each institution, and consideration given to regulating use of broad-spectrum antibiotics. LIMITATIONS: Results cannot be generalized as the study did not include all tertiary hospitals in these cities.

An unusual case of delayed-type hypersensitivity to ceftriaxone and meropenem.

Recent studies have demonstrated a low cross-reactivity between ß-lactam antibiotics and carbapenems in IgE-mediated reactions. There are no studies on cross-reactivity of meropenem in patients with non-immediate hypersensitivity to cephalosporins. We describe a case of a 13-year-old male, admitted in Neurosurgery with a severe extradural empyema complicating frontal sinusitis, submitted to an emergent bifrontal craniotomy. A generalized maculopapular exanthema, fever and malaise, appeared by the 7th day of meningeal doses of ceftriaxone, clindamycin and vancomycin. Those were replaced by meropenem, with posterior worsening of the reaction and mucosal involvement. A new scheme with amikacin, metronidazole and linezolid was done with improvement. Skin prick, intradermal and patch tests to penicillins, ceftriaxone and meropenem were negative. Lymphocyte transformation test was positive to ceftriaxone and negative to meropenem.Non-immediate T cell mechanism seems to be involved. Diagnosis work-up couldn't exclude cross-reactivity between ceftriaxone and meropenem.

ß-Lactam antibiotics form distinct haptenic structures on albumin and activate drug-specific T-lymphocyte responses in multiallergic patients with cystic fibrosis.

ß-Lactam antibiotics provide the cornerstone of treatment for respiratory exacerbations in patients with cystic fibrosis. Unfortunately, approximately 20% of patients develop multiple nonimmediate allergic reactions that restrict therapeutic options. The purpose of this study was to explore the chemical and immunological basis of multiple ß-lactam allergy through the analysis of human serum albumin (HSA) covalent binding profiles and T-cell responses against 3 commonly prescribed drugs; piperacillin, meropenem, and aztreonam. The chemical structures of the drug haptens were defined by mass spectrometry. Peripheral blood mononuclear cells (PBMC) were isolated from 4 patients with multiple allergic reactions and cultured with piperacillin, meropenem, and aztreonam. PBMC responses were characterized using the lymphocyte transformation test and IFN-γ /IL-13 ELIspot. T-cell clones were generated from drug-stimulated T-cell lines and characterized in terms of phenotype, function, and cross-reactivity. Piperacillin, meropenem, and aztreonam formed complex and structurally distinct haptenic structures with lysine residues on HSA. Each drug modified Lys190 and at least 6 additional lysine residues in a time- and concentration-dependent manner. PBMC proliferative responses and cytokine release were detected with cells from the allergic patients, but not tolerant controls, following exposure to the drugs. 122 CD4+, CD8+, or CD4+CD8+ T-cell clones isolated from the allergic patients were found to proliferate and release cytokines following stimulation with piperacillin, meropenem, or aztreonam. Cross-reactivity with the different drugs was not observed. In conclusion, our data show that piperacillin-, meropenem-, and aztreonam-specific T-cell responses are readily detectable in allergic patients with cystic fibrosis, which indicates that multiple ß-lactam allergies are instigated through priming of naïve T-cells against the different drug antigens. Characterization of complex haptenic structures on distinct HSA lysine residues provides a chemical basis for the drug-specific T-cell response.

Tolerability of meropenem in children with IgE-mediated hypersensitivity to penicillins.

BACKGROUND: Administration of meropenem to penicillin-allergic patients who might benefit from this treatment is usually avoided because of a 47.4% rate of cross-reactivity to imipenem, the prototype of the carbapenem class of beta-lactam antibiotics, demonstrated in a single study on the basis of positive responses to skin tests with imipenem reagents. However, recent studies of ours have demonstrated a very low rate of cross-reactivity between penicillins and both meropenem and imipenem in adults. OBJECTIVE: To assess cross-reactivity and tolerability of meropenem in children with documented penicillin allergy. METHODS: One hundred and eight consecutive children who had suffered a total of 129 immediate reactions (120 urticarial and/or angioedematous manifestations and 9 anaphylactic shocks) to penicillins and had positive results to skin tests for at least one of the penicillin reagents tested underwent skin tests with meropenem and negative subjects were challenged with it. RESULTS: One subject (0.9%) displayed a positive intradermal test to meropenem. The remaining 107 subjects with negative skin tests to meropenem tolerated challenges. Challenges were not followed by full therapeutic courses. CONCLUSIONS: Our results demonstrate a low rate of cross-reactivity between penicillins and meropenem. Therefore, the practice of avoiding meropenem in children with immunoglobulin E-mediated hypersensitivity could be abandoned; in those who especially require meropenem treatment, prophylactic skin tests are advisable, because negative results indicate tolerability.

Brief communication: tolerability of meropenem in patients with IgE-mediated hypersensitivity to penicillins.

BACKGROUND: Although clinicians avoid giving meropenem to patients with penicillin allergy because of potential cross-reactivity, the rate of cross-reactivity between penicillins and meropenem has not been prospectively determined. OBJECTIVE: To assess the tolerability of meropenem in patients with documented penicillin allergy. DESIGN: Prospective skin testing and antibiotic challenge. SETTING: Allergy units of 2 Italian medical centers. PATIENTS: 104 consecutive participants with immediate hypersensitivity reactions to penicillins and positive skin test results to at least 1 penicillin reagent. MEASUREMENTS: Skin tests to meropenem and, if results were negative, challenges with escalating doses of meropenem. RESULTS: One participant (0.9% [95% CI, 0.02% to 5.2%]) had a positive intradermal test result to meropenem. The remaining 103 participants with negative skin test results to meropenem tolerated escalating dose challenges. LIMITATION: Challenges were not followed by therapeutic courses. CONCLUSIONS: These data indicate a low rate of cross-reactivity between penicillins and meropenem. Therefore, the practice of avoiding meropenem therapy in penicillin-allergic patients should be reconsidered. In patients who especially require meropenem treatment, the authors recommend pretreatment skin tests because negative results indicate tolerability.

Successful meropenem desensitization in a patient with cystic fibrosis.

OBJECTIVE: To report a case of successful meropenem desensitization in a patient with cystic fibrosis (CF) with documented hypersensitivity to multiple antibiotics including carbapenems. CASE SUMMARY: A 20-year-old white man with CF was admitted to the hospital for treatment of an acute pulmonary exacerbation caused by multidrug-resistant Burkholderia cepacia complex and methicillin-resistant Staphylococcus aureus (MRSA). Past treatments of his CF exacerbations were complicated by urticarial eruptions following administration of beta-lactams, including meropenem, and ototoxicity from aminoglycosides. Skin testing revealed hypersensitivity reactions to beta-lactam antibiotics including penicillin, piperacillin/tazobactam, ceftazidime, and imipenem. A literature review (MEDLINE, January 3, 2002) and communication with the manufacturer of meropenem revealed no specific information on desensitizing patients to this agent. Because of meropenem's activity against B. cepacia complex alone and in combination with other antimicrobials, a desensitization protocol was adapted and applied to meropenem in an effort to provide the most beneficial treatment available. A 12-dose escalation protocol was successfully employed without incident. DISCUSSION: Antimicrobial therapy is limited in CF patients by susceptibility profiles of common infecting organisms (e.g., Pseudomonas spp., B. cepacia complex, MRSA). Unfortunately, host responses may further reduce the utility of many effective antibiotic classes due to hypersensitivity and/or adverse reactions. Desensitization is a useful alternative that allows the administration of beneficial medications to patients with documented allergy histories. CONCLUSIONS: Meropenem is an important treatment option in the CF population, particularly due to its activity against B. cepacia complex. Successful desensitization using a dose-escalation protocol in patients with a documented carbapenem allergy will allow the most beneficial therapy to continue.

Serum sickness-like reaction possibly associated with meropenem use.

Serum sickness-like reactions most commonly occur secondary to drug administration. We describe a serum sickness-like reaction that was possibly associated with meropenem therapy.

Immune response in patients with intra-abdominal infections treated with carbapenems.

The immune responses against isolated microorganisms in patients with intraabdominal infections treated with meropenem or imipenem/cilastatin were investigated. Fifty-nine patients received meropenem 500 mg t.i.d. intravenously for 3-21 days (mean 5.4 days) and 50 patients imipenem/cilastatin 500 mg/500 mg t.i.d. intravenously for 3-17 days (mean 5.1 days). Three serum samples were taken from each patient, the first sample at admission, the second sample between three and seven days after start of antibiotic treatment, and the third sample between 14 and 28 days later. Ninety-eight per cent of the patients in the meropenem group and 95% of the patients in the imipenem/cilastatin group were cured. There was no difference in the clinical outcome between the two treatment groups. Escherichia coli, Bacteroides fragilis group, anaerobic cocci, Staphylococcus epidermidis, and Klebsiella spp. predominated among the isolated microorganisms. Thirty-nine patients in the meropenem group had significant immune responses against one or more of the isolated microorganisms while 31 patients in the imipenem/group had significant responses. E. coli and B. fragilis gave rise in antibody titres in most patients indicating that these species are the most important pathogens in intraabdominal infections.

Imipenem cross-reactivity with penicillin in humans.

We examined the potential for IgE-mediated cross-reactivity between the carbepenems, a new class of beta-lactam antibiotics, represented by imipenem, and penicillins. In vivo skin testing with the relevant imipenem and penicillin determinants was undertaken. Having determined the concentrations of imipenem materials that did not induce false positive skin tests in nonpenicillin-allergic control subjects, we tested 40 subjects with a history of penicillin-allergic reactions. Twenty of these subjects were found to be nonallergic to penicillin on skin testing, and none of these subjects reacted to the imipendem determinants. In contrast, half the 20 subjects who were positive to one or more penicillin determinants also reacted to imipenem reagents. There was a good correlation between the penicillin and imipenem reagents to which the patients reacted. Imipenem should only be administered to penicillin-allergic subjects with similar precautions of penicillin administration to such patients.

Immunogenicity and allergenicity studies on two beta-lactam structures, a clavam, clavulanic acid, and a carbapenem: structure-activity relationships.

Two newer beta-lactam-containing structures, a clavam, clavulanic acid, and a carbapenem, MM22383, have been studied for their intrinsic immunogenicity and allergenicity. Clavulanic acid has a very low immunogenic and allergenic potential, in contrast to MM22383 which is a contact sensitiser in guinea pigs and an immunogen in rabbits. Evidence for the allergenic potential of MM22383 in man through occupational exposure is also presented. Consideration of the chemistry of these two compounds with respect to their reactivity with protein provides a rationale for the marked difference in their behaviour. The importance of stable hapten-protein conjugates and epitope density is discussed in relation to immunogenicity.