Morganella sp.

Morganella sp.In the late 1930s, M morganii was identified as a cause of urinary tract infections. In 1984, McDermott reported 19 episodes of M morganii bacteremia in 18 patients during a 5.5-year period at a Veterans Administration hospital.[2] Eleven of the episodes occurred in surgical patients. The most common source of bacteremia was postoperative wound infection, and most infections occurred in patients who had received recent therapy with a beta-lactam antibiotic. In 2011, Kwon et al reported a case of a 65-year-old man with an infected aortic aneurysm in which the pathogen was M morganiiSnakebites: M morganii is commonly found in the mouths of snakes. As a result, it is one of the organisms recovered most often from snakebite infections. small oxidase-negative catalase and indole-positive gram-negative rodsFerments: - glucose - mannose

M morganii is motile, facultative anaerobic, and non-capsulated, and it hydrolyzes urease and reduces nitrates.Unlike Proteus species, swarming does not occur. Currently, Morganella contains only a single species, M morganii, with 2 subspecies, morganii and sibonii. M morganii was previously classified under the genus Proteus as Proteus morganii.Morganella morganii is a gram-negative rod commonly found in the environment and in the intestinal tracts of humans, mammals, and reptiles as normal floraDespite its wide distribution, it is an uncommon cause of community-acquired infection and is most often encountered in postoperative and other nosocomial settings. M morganii infections respond well to appropriate antibiotic therapy; however, its natural resistance to many beta-lactam antibiotics may lead to delays in proper treatment.6PATHOPHYSIOLOGYUTISepsisPneumoniaWound infectionsMusculoskeletal infectionsCNS infectionsPericarditis

Spontaneous bacterial peritonitisEndophthalmitisEmpyemaChorioamnionitisNeonatal infections

Like Proteus species, M morganii has properties that enhance its ability to infect the urinary tract; these include motility and the ability to produce ureaseUTIs due to Morganella should be treated with oral quinolones like ciprofloxacin.

Nosocomial wound infections can often be due to Morganella species (22, 37). These infections can be polymicrobial or monobacterial in origin.

Neonates-It is thought that the neonate acquires the infection probably from overt or subtle chorioamnionitis in the mother. The other risk factor of acquisition of these bacteria in a neonate may be use of ampicillin as prophylactic therapy during pregnancy. 7

FrequencyUnited States

M morganii is a rare cause of severe invasive disease. It accounts for less than 1% of nosocomial infections. M morganii is usually opportunistic pathogen in hospitalized patients, particularly those on antibiotic therapy.EPIDEMIOLOGYLaboratory Studies

Positive:-Urease-Methyl Red-Ornithine Decarboxylase-Phenylalanine deaminase-Gas from D-glucoseKCN growthresistant to:penicillin, ampicillin, ampicillin/sulbactam, oxacillin, first-generation and second-generation cephalosporins, erythromycin, tigecycline, colistin, and polymyxin B.RESISTANCE AND SUSCEPTIBILITYnaturally susceptible to:piperacillin, ticarcillin, mezlocillin, third-generation and fourth-generation cephalosporins, carbapenems, aztreonam, fluoroquinolones, aminoglycosides, and chloramphenicol.These -lactamases are typically inducible in the presence of -lactam antibiotics (10), with only trace amounts being produced in the absence of antibiotics. In the presence of enzyme-inducing antibiotics these enzymes may lead to expression of high-level resistanceA second mechanism of -lactam resistance in Morganella is the chromosomally mediated hyperproduction of -lactamases. These strains have mutations at the ampD locus leading to stable derepression of the -lactamase gene and permanent production of excessive enzyme levels. 14Initiate treatment with an extended-spectrum antipseudomonal cephalosporin orpenicillin combined with an aminoglycoside. Preferred beta-lactam antibiotics include: cefepime, ceftazidime, aztreonam, piperacillin, and piperacillin-tazobactam. Carbapenems (ie, imipenem, meropenem) and intravenous fluoroquinolones are reserved for resistant cases.TREATMENT