CONSEQUENCES OF THE INOCULUM EFFECT AGAINST Β-LACTAMS IN METHICILLIN-SUSCEPTIBLE STAPHYLOCOCCUS AUREUS (MSSA) STRAINS

Moumperra Chral Oglou; Serap Şimşek Yavuz; Gülşen Günel; Zerrin Aktaş; Elif Nurtop; Füsun Can; Haluk Eraksoy

Makale detayları

CONSEQUENCES OF THE INOCULUM EFFECT AGAINST Β-LACTAMS IN METHICILLIN-SUSCEPTIBLE STAPHYLOCOCCUS AUREUS (MSSA) STRAINS

Yazarlar:

Moumperra Chral Oglou | Serap Şimşek Yavuz | Gülşen Günel | Zerrin Aktaş | Elif Nurtop | Füsun Can | Haluk Eraksoy

Yayıncı:

Istanbul University

Ana Başlıklar:

Bulaşıcı Hastalıklar

Dergi:

İstanbul Tıp Fakültesi Dergisi Vol.88 Issue 3, pp.216-226

Belge Tipi:

Makale

Yayın Tarihi:

7/2025

Belge Dili:

İngilizce

Document ID (Org No.):

2001356762

pISSN:

1305-6441

Anahtar kelimeler:

Özet:

 Objective: Some staphylococcal β-lactamases could destroy β lactams other than penicillin, including cefazolin Cz and ampi cillin-sulbactam SAM, especially in the presence of higher inocu lum, which is called the inoculum effect InE. We investigated the incidence and clinical implications of InE against different β-lac tams including in S.aureus MSSA strains isolated from bacteremic patients. Material and Methods: Patients with MSSA bacteraemia were included. MSSA strains were tested with the disk diffusion and broth microdilution method at standard and high inoculum. The presence and type of β-lactamases were confirmed by PCR plus DNA sequencing. InE was defined as a 4-fold or greater increase in minimal inhibitor concentration MIC values at high inoculum. Patient data were obtained retrospectively. Results: 85 of the 52 MSSA strains were Type A β-lactamase positive. 25, 38.5, and 3.8 of the strains showed InE against Cz, SAM, and ceftriaxone, respectively. The mortality rate in patients infected with MSSA strains showing SAMInE and treated with SAM was significantly higher than in those not treated with SAM p0.044, OR 7.8, 95. Conclusion: SAM was the most affected β-lactam by type A β lactamase of MSSA strains, followed by Cz, and this effect became more prominent with higher inoculum. SAM treatment of the patients infected with the MSSA strains showing SAMInE may increase mortality.

 Objective: Some staphylococcal β-lactamases could destroy β lactams other than penicillin, including cefazolin Cz and ampi cillin-sulbactam SAM, especially in the presence of higher inocu lum, which is called the inoculum effect InE. We investigated the incidence and clinical implications of InE against different β-lac tams including in S.aureus MSSA strains isolated from bacteremic patients. Material and Methods: Patients with MSSA bacteraemia were included. MSSA strains were tested with the disk diffusion and broth microdilution method at standard and high inoculum. The presence and type of β-lactamases were confirmed by PCR plus DNA sequencing. InE was defined as a 4-fold or greater increase in minimal inhibitor concentration MIC values at high inoculum. Patient data were obtained retrospectively. Results: 85 of the 52 MSSA strains were Type A β-lactamase positive. 25, 38.5, and 3.8 of the strains showed InE against Cz, SAM, and ceftriaxone, respectively. The mortality rate in patients infected with MSSA strains showing SAMInE and treated with SAM was significantly higher than in those not treated with SAM p0.044, OR 7.8, 95. Conclusion: SAM was the most affected β-lactam by type A β lactamase of MSSA strains, followed by Cz, and this effect became more prominent with higher inoculum. SAM treatment of the patients infected with the MSSA strains showing SAMInE may increase mortality.

 Objective: Some staphylococcal β-lactamases could destroy β lactams other than penicillin, including cefazolin Cz and ampi cillin-sulbactam SAM, especially in the presence of higher inocu lum, which is called the inoculum effect InE. We investigated the incidence and clinical implications of InE against different β-lac tams including in S.aureus MSSA strains isolated from bacteremic patients. Material and Methods: Patients with MSSA bacteraemia were included. MSSA strains were tested with the disk diffusion and broth microdilution method at standard and high inoculum. The presence and type of β-lactamases were confirmed by PCR plus DNA sequencing. InE was defined as a 4-fold or greater increase in minimal inhibitor concentration MIC values at high inoculum. Patient data were obtained retrospectively. Results: 85 of the 52 MSSA strains were Type A β-lactamase positive. 25, 38.5, and 3.8 of the strains showed InE against Cz, SAM, and ceftriaxone, respectively. The mortality rate in patients infected with MSSA strains showing SAMInE and treated with SAM was significantly higher than in those not treated with SAM p0.044, OR 7.8, 95. Conclusion: SAM was the most affected β-lactam by type A β lactamase of MSSA strains, followed by Cz, and this effect became more prominent with higher inoculum. SAM treatment of the patients infected with the MSSA strains showing SAMInE may increase mortality.

 Amaç: Bazı stafilokoksik β-laktamazlar, özellikle daha yüksek inokulum varlığında, sefazolin Cz ve ampisilin-sulbaktam SAM dahil olmak üzere penisilin dışındaki β-laktamları parçayalabilir ki buna inokulum etkisi InE denir. Bu çalışmada bakteriyemik hastalardan izole edilen S.aureusMSSA suşlarında farklı β-laktamlara karşı InEnin insidansı ve klinik etkileri araştırılmıştır. Gereç ve Yöntemler: Çalışmaya MSSA bakteriyemisi olan hastalar dahil edildi. MSSA suşları, standart ve yüksek inokulumda disk difüzyon ve sıvı mikrodilüsyon yöntemi ile test edildi. β-laktama zların varlığı ve tipi PCR artı DNA dizilemesi ile doğrulandı. InE, yüksek inokulumda minimal inhibtör konsantrasyon MİK değerlerinde 4 kat veya daha fazla artış olarak tanımlandı. Hasta verileri retrospektif olarak elde edildi. Bulgular: 52 MSSA suşunun 85i Tip A β-laktamaz pozitifti. Suşların 25i, 38,5i ve 3,8i sırasıyla Cz, SAM ve seftriaksona karşı InE gösterdi. SAMInE gösteren MSSA suşlarıyla infekte olmuş ve SAM ile tedavi edilen hastalardaki ölüm oranı, SAM ile tedavi edilmeyenlere göre önemli ölçüde daha yüksekti p0,044, OR 7,8. Sonuç: MSSA suşlarının tip A β-laktamazı tarafından en çok etkile nen β-laktamın SAM olduğu, bunu Cznin takip ettiği ve bu etkinin daha yüksek inokulumla daha belirgin hale geldiği görülmüştür. SAMInE gösteren MSSA suşlarıyla infekte olmuş bakteriyemili hastaların SAMla tedavisi ölüm oranını artırabilir.

Makale detayları

CONSEQUENCES OF THE INOCULUM EFFECT AGAINST Β-LACTAMS IN METHICILLIN-SUSCEPTIBLE STAPHYLOCOCCUS AUREUS (MSSA) STRAINS

Yazarlar:

Moumperra Chral Oglou | Serap Şimşek Yavuz | Gülşen Günel | Zerrin Aktaş | Elif Nurtop | Füsun Can | Haluk Eraksoy

Yayıncı:

Istanbul University

Ana Başlıklar:

Bulaşıcı Hastalıklar

Dergi:

İstanbul Tıp Fakültesi Dergisi Vol.88 Issue 3, pp.216-226

Belge Tipi:

Makale

Yayın Tarihi:

7/2025

Belge Dili:

İngilizce

Document ID (Org No.):

2001356762

pISSN:

1305-6441

Ampicillin-sulbactam

bacteraemia

cefazolin

inoculum effect

MSSA

Staphylococcus aureusAmpisilin-sulbaktam

bakteriyemi

sefazolin

inokulum etkisi

MSSA

Staphylococcus aureus

Sayı

Makale detayları

Yazarlar: Moumperra Chral Oglou | Serap Şimşek Yavuz | Gülşen Günel | Zerrin Aktaş | Elif Nurtop | Füsun Can | Haluk Eraksoy

Yayıncı: Istanbul University

Ana Başlıklar: Bulaşıcı Hastalıklar

Dergi: İstanbul Tıp Fakültesi Dergisi Vol.88 Issue 3, pp.216-226

Belge Tipi: Makale

Yayın Tarihi: 7/2025

Belge Dili: İngilizce

Document ID (Org No.): 2001356762

pISSN: 1305-6441

Sayı

Yazarlar:

Moumperra Chral Oglou | Serap Şimşek Yavuz | Gülşen Günel | Zerrin Aktaş | Elif Nurtop | Füsun Can | Haluk Eraksoy

Yayıncı:

Istanbul University

Ana Başlıklar:

Bulaşıcı Hastalıklar

Dergi:

İstanbul Tıp Fakültesi Dergisi Vol.88 Issue 3, pp.216-226

Belge Tipi:

Makale

Yayın Tarihi:

7/2025

Belge Dili:

İngilizce

Document ID (Org No.):

2001356762

pISSN:

1305-6441