Subha A, Ananthan S, Alavandi S V
Department of Microbiology, Dr ALM Postgraduate Institute of Basic Medical Sciences, Chennai, India.
Indian J Med Res. 2001 May;113:181-5.
BACKGROUND & OBJECTIVES: Extended spectrum beta-lactamases (ES beta L) are enzymes produced in some Gram-negative bacilli that mediate resistance to third generation cephalosporins (3GC) and aztreonam. These are common in Klebsiella spp. and Escherichia coli and in other members of the family enterobacteriaceae. ES beta L production is accompanied by resistance to other antibiotics as these are encoded by multi drug resistance conjugative plasmids. The present study was undertaken to study the incidence of multi drug resistant and ES beta L producing Klebsiella spp. in children under five years of age suffering from intestinal and extraintestinal infections.
A total of 90 strains of Klebsiella spp. (76 isolates of K. pneumoniae and 14 of K. oxytoca) were tested for resistance to 3GC antibiotics (ceftazidime, cefotaxime, ceftriaxone), amikacin, ampicillin, erythromycin, gentamycin and streptomycin by disc diffusion method. Isolates found resistant to 3GC antibiotics were tested for the production of ES beta L by double disc diffusion synergy test. Transconjugation experiments were done to study the transfer of drug resistance and ES beta L production from Klebsiella isolates to an Esch. coli strain (K12 J62-2).
All the 90 isolates showed multi drug resistance; 87 (96.6%) isolates showed resistance or decreased susceptibility to at least one of the three 3GC. ES beta L production was detected in four strains of K. pneumoniae and two K. oxytoca. ES beta L activity could be experimentally transferred to recipient Esch. coli in all the 6 isolates. Resistance to beta-lactam antibiotics was co-transferred along with resistance to gentamycin.
INTERPRETATION & CONCLUSION: This study has shown the incidence of ES beta L producing Klebsiella strains in children in Chennai, and possibly poses a threat in the treatment and management of Klebsiella associated infections. The incidence of ES beta L producing strains of Klebsiella and other members of enterobacteriaceae should be carefully monitored in children to prevent unnecessary use of antibiotics especially 3GC and aminoglycoside antibiotics. Hence, tests for the detection of ES beta L producing Klebsiella strains should be carried out routinely for better therapeutic management.
超广谱β-内酰胺酶（ESβL）是某些革兰氏阴性杆菌产生的酶，可介导对第三代头孢菌素（3GC）和氨曲南的耐药性。这些酶在克雷伯菌属、大肠埃希菌及肠杆菌科的其他成员中很常见。产生ESβL的同时还会对其他抗生素耐药，因为这些耐药性由多重耐药接合质粒编码。本研究旨在调查5岁以下患有肠道和肠道外感染的儿童中多重耐药及产ESβL克雷伯菌属的发生率。
采用纸片扩散法对总共90株克雷伯菌属菌株（76株肺炎克雷伯菌和14株产酸克雷伯菌）进行了对3GC抗生素（头孢他啶、头孢噻肟、头孢曲松）、阿米卡星、氨苄西林、红霉素、庆大霉素和链霉素的耐药性检测。对发现对3GC抗生素耐药 的菌株，通过双纸片扩散协同试验检测ESβL的产生情况。进行了接合试验，以研究耐药性和ESβL产生从克雷伯菌分离株向大肠埃希菌菌株（K12 J62-2）的转移情况。
所有90株分离株均显示多重耐药；87株（96.6%）分离株对三种3GC中的至少一种表现出耐药或敏感性降低。在4株肺炎克雷伯菌和2株产酸克雷伯菌中检测到了ESβL的产生。在所有6株分离株中，ESβL活性均可通过实验转移至受体大肠埃希菌。对β-内酰胺类抗生素的耐药性与对庆大霉素的耐药性一起被共同转移。
本研究显示了钦奈儿童中产ESβL克雷伯菌菌株的发生率，这可能对克雷伯菌相关感染的治疗和管理构成威胁。应密切监测儿童中产ESβL克雷伯菌菌株及肠杆菌科其他成员的发生率，以防止不必要地使用抗生素，尤其是3GC和氨基糖苷类抗生素。因此，为了更好地进行治疗管理，应常规开展检测产ESβL克雷伯菌菌株的试验。
