PurposeColistin is a drug of last resort for treating multidrug-resistant Acinetobacter baumannii infections. Unfortunately, colistin-resistant A. baumannii (CoR-AB) has been reported. Here, we examined the in vitro effect of mono- and combined antimicrobials against CoR-AB strains and their resistance mechanism, and evaluated the clinical outcomes of CoR-AB-infected patients.Patients and methodsSeventeen clinical CoR-AB strains were isolated from patients at Phramongkutklao hospital, 2011–2015. The mono- and synergistic activities of colistin, tigecycline, sulbactam, imipenem, meropenem, amikacin, fosfomycin, and cotrimoxazole were examined by minimum inhibitory concentration (MIC) and fractional inhibitory concentration index. Clonal relationship and resistance genes were determined by repetitive extragenic palindromic polymerase chain reaction with specific primers. The effect of carbonyl cyanide 3-chlorophenylhydrazone combined with colistin was used to test efflux pump involvement. Patient treatment outcomes were also reported.ResultsThe most prevalent infection in CoR-AB patients was pneumonia (35.3%), and all patients were administered colistin combined with another agent. The 30-day mortality was 70.6%, and the colistin MIC range and MIC50 was 16–512 μg/mL and 64 μg/mL, respectively. All CoR-AB strains were sensitive to tigecycline. Sporadic isolates were susceptible to sulbactam, imipenem, meropenem, and cotrimoxazole. A synergistic or additive effect was observed for colistin plus imipenem or meropenem (16.7%), sulbactam (66.7%), or tigecycline (66.7%). The CoR-AB isolates could be divided into four different clones (A–D) with a high prevalence of group B (47.1%). Eight isolates harbored blaOXA23, blaIMP, blaKPC, and blaNDM, and one contained blaOXA23, blaIMP, and blaKPC, while the eight remaining isolates carried only blaOXA23. The MIC values of all strains were greatly reduced for colistin plus carbonyl cyanide 3-chlorophenylhydrazone.ConclusionCoR-AB clinical isolates exhibited very high colistin resistance and a high frequency of resistance genes. The mechanism of colistin resistance appears to be mediated via an efflux pump. Thus, certain antimicrobials could be used as salvage therapy for CoR-AB infection.

Global infections with colistin-resistant Pseudomonas aeruginosa (CoR-PA) are increasing; there are currently very few studies focused on the antimicrobial susceptibility of CoR-PA isolates, and none from Thailand. Here, we investigated the impact of various antimicrobials, alone and in combination, via the in vitro testing of CoR-PA clinical isolates. Eighteen CoR-PA isolates were obtained from patients treated at Phramongkutklao Hospital from January 2010 through June 2019; these were classified into six different clonal types by using the enterobacterial repetitive intergenic consensus (ERIC)-PCR method, with a high prevalence of Group A (27.8%). The antimicrobial susceptibility was determined as the minimal inhibitory concentrations (MICs) using the epsilometer-test (E-test) method. The synergistic activities of six antimicrobial combinations were reported via the fractional-inhibitory-concentration index. All CoR-PA isolates were susceptible to amikacin, meropenem, and ceftolozane/tazobactam, but only 5.56% were susceptible to imipenem. In vitro synergistic activities were detected for amikacin with aztreonam, piperacillin/tazobactam, meropenem, and ceftazidime for 16.67%, 11.11%, 11.11%, and 5.55%, respectively. One CoR-PA isolate carried the blaVIM metallo-β-lactamase gene; none carried mcr-1 genes or detected plasmid-mediated AmpC β-lactamase or an overproduction of chromosomal AmpC β-lactamase. Seven CoR-PA isolates (38.89%) were capable of biofilm formation. In conclusion, CoR-PA isolates are highly susceptible to antimicrobials; the synergy observed in response to the various agents should be examined in a clinical setting.

Background: Streptococcus gallolyticus, formerly known as one of the Streptococcus bovis group, is frequently associated with endocarditis. Current guidelines recommended diagnostic work-up for endocarditis among patients with S. gallolyticus bacteremia. However, S. gallolyticus subsp. pasteurianus, was found to be associated with neonatal sepsis and liver diseases and is less commonly associated with endocarditis compared with S. gallolyticus subsp. gallolyticus. Our study aimed to identify the risk factors for S. gallolyticus subsp. pasteurianus endocarditis to help select the patients for echocardiography. Methods: In this retrospective cohort study, medical records from all adult patients with S. gallolyticus subsp. pasteurianus isolated from blood cultures at Phramongkutklao Hospital from 2009 to 2015 were reviewed. Patients who had mixed bacteremia or missing records were excluded from the study. Results: During the study period, S. gallolyticus subsp. pasteurianus was isolated among 106 individuals. Mean age was 66.9±15.6 years. Most patients (61.3%) were male, with cirrhosis as the most common underlying diseases (46.2%), followed by malignancy and chronic kidney disease. Most common manifestations included primary bacteremia (44.3%), followed by spontaneous bacterial peritonitis (23.6%). Infective endocarditis was found among 9 patients. No patients with cirrhosis or single blood specimen of bacteremia had endocarditis (RR 0; p-value 0.003, and RR 1.35; p-value 0.079). The common complications associated with endocarditis were acute respiratory failure (RR 4.32; p-value 0.05), whereas acute kidney injury was a protective factor (RR 0; p-value 0.01). Among 76 patients who had records of 2-year follow-up, no new diagnosis of endocarditis or malignancy was observed. Conclusion: Among patients with S. gallolyticus subsp. pasteurianus bacteremia, echocardiography might not be needed among patients with cirrhosis and without sustained bacteremia.

GEP is a severe cutaneous reactions to drugs, 1 approximately 90% of cases are caused by medications and other particular cases are induced by viral infections or mercury hypersensitivity. 2 Typically, patients with AGEP present with rapid onset of many non-follicular, sterile pustules on an erythematous base. The most common sites are intertriginous zones, trunk, and upper extremities, conversely mucous membrane is rarely involved. Fever and leukocytosis are often accompanied with skin manifestation. Histology is a confirmation test. Discontinuation of the causative drug and symptomatic treatment is the best management. All skin lesions resolved spontaneously within 15 days. 3,4 Imipenem, a broad spectrum carbapenem antibiotic, has potent activity against Gram positive, Gram negative and obligate anaerobic bacteria. Imipenem is widely used to treat nosocomial infections, especially Pseudomonas aeruginosa, extended beta lactamase producing and Amp-C producing pathogens. Imipenem is well tolerated, and has a low incidence of adverse drug reaction. The most common adverse effects are gastrointestinal disturbance, cutaneous hypersensitivity reaction and seizures in patients with cerebral cortical lesions, a history of seizure, or renal insufficiency. [5][6][7] This report describes AGEP caused selectively by imipenem in the patient, who was able to tolerate ertapenem. Case ReportA 65-year-woman with systemic sclerosis and CREST syndrome (calcinosis, Raynaud phenomenon, esophageal dysmotility, sclerodactyly, and telangiectasia) was re-admitted due to relapsing Salmonellosis. At the last admission, she presented with fever, abdominal pain, and acute diarrhea. Salmonella group B was isolated from blood culture. She was diagnosed with Salmonella group B septicemia and treated with intravenous ertapenem for 2 weeks. Around 3 weeks after being discharged from hospital, she had fever, malaise, anorexia and back pain for one week. Plain thoracic spine radiograph revealed a fracture of the 7 th and 9 th thoracic spine. She had a declined renal function, T1W with Gadolinium was not performed. Blood and urine cultures were positive as Salmonella group B being resistant to third

Background: Streptococcus gallolyticus, formerly known as one of the Streptococcus bovis group, is frequently associated with endocarditis. Current guidelines recommended diagnostic work-up for endocarditis among patients with S. gallolyticus bacteremia. However, S. gallolyticus subsp. pasteurianus, was found to be associated with neonatal sepsis and liver diseases and is less commonly associated with endocarditis compared with S. gallolyticus subsp. gallolyticus. Our study aimed to identify the risk factors for S. gallolyticus subsp. pasteurianus endocarditis to help select the patients for echocardiography . Methods: In this retrospective cohort study, medical records from all adult patients with S. gallolyticus subsp. pasteurianus isolated from blood cultures at Phramongkutklao Hospital from 2009 to 2015 were reviewed. Patients who had mixed bacteremia or missing records were excluded from the study. Result: During the study period, S. gallolyticus subsp. pasteurianus were isolated among 106 individuals. Mean age was 66.9±15.6 years. Most patients (61.3%) were male, with cirrhosis as the most common underlying diseases (46.2%), followed by malignancy and chronic kidney disease. Most common manifestations included primary bacteremia (44.3%), followed by spontaneous bacterial peritonitis (23.6%). Infective endocarditis was found among 9 patients. No patients with cirrhosis or single blood specimen of bacteremia had endocarditis (RR 0; p-value 0.003, and RR 1.35; p-value 0.079). The common complications associated with endocarditis were acute respiratory failure (RR 4.32; p-value 0.05), whereas acute kidney injury was a protective factor (RR 0; p-value 0.01). Among 76 patients who had records of 2-year follow-up, no new diagnosis of endocarditis or malignancy was observed. Conclusion: Among patients with S. gallolyticus subsp. pasteurianus bacteremia, echocardiography might not be needed among patients with cirrhosis or transient bacteremia. Key word: Streptococcus gallolyticus subspecies pasteurianus , endocarditis