Context:The morbidity potentially associated with unverified penicillin allergy in pregnant women, with and without group B streptococcus (GBS) infections, is unknown. Penicillin allergy testing is safe during pregnancy but is done infrequently.Objective: To determine morbidity associated with antibiotic use in a large cohort of pregnant women, with and without an unverified history of penicillin allergy, and with and without GBS.Design: Retrospective. All pregnant women who delivered live infants in Kaiser Permanente Southern California between January 1, 2009, and December 31, 2014, were identified.Main Outcome Measures: Penicillin allergy status at delivery, delivery method, maternal and infant hospital utilization, peripartum antibiotic exposures, new antibioticassociated adverse drug reactions, and new Clostridium difficile infections.Results: There were 170,379 unique women who had 201,316 pregnancies during the study period. There were 16,084 pregnancies in women with an active, but unverified, penicillin allergy at delivery. There were 42,524 pregnancies in GBS-positive women, and 3500 also had a penicillin allergy. Women with a penicillin allergy, with or without GBS, had significantly (about 10%) higher cesarean section rates and spent significantly more (about 0.1) days in the hospital after delivery. Among GBS-positive women, those with an unverified penicillin allergy were exposed to significantly more cefazolin, clindamycin, vancomycin, and gentamicin and had significantly higher rates of adverse drug reactions associated with all antibiotic use.Conclusions: Unverified penicillin allergy is associated with more hospital utilization and additional morbidity. Penicillin allergy testing of pregnant women with a history of penicillin allergy may help reduce these unwanted outcomes.

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Introduction: Irritable bowel syndrome (IBS) and diverticulitis share clinical features. Misdiagnosed diverticulitis can cause unnecessary antibiotic therapy. Among IBS and non-IBS patients, we compared outpatient, clinically diagnosed (no computed tomography) diverticulitis rates. Among primary-care, diverticulitis-diagnosed IBS patients, we assessed imaged diverticulosis and probable misdiagnosed diverticulitis. Methods: Among 3836-patient IBS and 67,827-patient non-IBS cohorts identified from 2000 to 2002, we retrospectively compared the frequency of outpatient, clinically diagnosed, antibiotic-treated diverticulitis from 2003 to endpoints of December 31, 2017, disenrollment, or death. In IBS patients, we reviewed records of initial, primary care-managed episodes for misdiagnosis. Results: In 3836 clinically diagnosed IBS and 63,991 non-IBS cohorts, followup (median [interquartile range]) was 12.4 (3.9 to 15.0) years versus 10.2 (3.0 to 15.0) years, respectively (P < .001). The incidence rate/1000 patient-years (95% CI) of diagnosed diverticulitis was 14.0 (12.1 to 16.3) and 4.2 (4.0 to 4.5), respectively, (crude incidence rate ratio, 3.3 [2.8-3.9]; P <. 001). Of examined features, the diagnosis of IBS was most strongly associated with clinically diagnosed diverticulitis (adjusted incidence rate ratio [95% CI]; 2.64 [2.21-3.15], P < .001). Of initial diverticulitis diagnoses in 189 IBS patients, objective evidence-based diagnosis revision or exclusion occurred in 12 (6.3%), including 6 hospitalized; 29 (15.3%) had colon imaging before and/or afterward without diverticulosis reported; 143 (75.1%) had image-documented diverticulosis; and 6 (3.2%) had no imaging. Conclusions: Outpatient, clinically diagnosed, antibiotic-treated diverticulitis was increased 3-fold in IBS patients. Primary care clinical misdiagnosis of initial episodes occurred in 1 of 5 patients, but additional misdiagnosis due to misattribution of IBS pain to diverticulitis is suggested.

RATIONALE: Betalactam antibiotics are the most frequent cause of hypersensitivity reactions to drugs mediated by a specific immune mechanism. Amoxicillin (AX) is the most often elicitor, which was originally prescribed alone, and is now often prescribed alongside clavulanic acid (CLV). After the administration of AX-CLV, there are subjects who develop AX allergy whilst tolerating CLV, whilst for others the opposite occurs. To our knowledge, there are no clinical reports of patients with IgE-mediated allergy to both AX and CLV. METHODS: Skin testing was performed by skin prick test and if negative followed by intradermal test. Serum specific IgE determination was performed by ImmunoCAP and basophil activation test (BAT) was performed by flow cytometry. Single blind placebo controlled drug provocation test was performed to assess tolerance to other penicillins. RESULTS: Case 1: 48 year-old woman who developed urticaria and angioedema 45 min after the oral administration of AX-CLV. Case 2: 43 year-old woman who developed systemic pruritus with generalised urticaria and facial and tongue angioedema 15 min after the oral administration of AX-CLV. The allergological work-up indicated that the two patients were allergic to both AX and CLV with good tolerance to BP and penicillin V. Both patients gave positive skin test results to AX and CLV, showed specific anti-AX IgE and gave positive BAT results to AX and CLV. CONCLUSIONS: Our study provides evidence that sensitization to both AX and CLV can appear in the same patient. To our knowledge this is the first study showing this sensitization pattern.