Microorganism	Notable information
Urgent
Clostridium difficileA1 ,A2	Deaths related to C. difficile increased 400% between 2000 and 2007, in part because of a stronger strain
	Most infections are connected to receiving medical care
	Hand sanitizer does not kill C. difficile, and hand washing may not be sufficient
Carbapenem-resistant Enterobacteriaceae A3	Difficult to treat and, in some cases, untreatable
	Kills up to one-half of patients who get bloodstream infections
	Easily spreads antibiotic resistance to other bacteria
Drug-resistant Neisseria gonorrhoeaeA4	Cases in the United States are more prevalent in the West and among men who have sex with men
	All patients treated for gonorrhea should routinely be offered condoms, referred for risk-reduction counseling, and retested for gonorrhea three months later
Serious
Multidrug-resistant AcinetobacterA5	Increasingly common in U.S. health care facilities; hard to treat
	Noted in U.S. service members wounded in Iraq and Afghanistan
Drug-resistant CampylobacterA6	Most cases are sporadic and not part of outbreaks
	Ciprofloxacin (Cipro) resistance to Campylobacter increased from 12% in 1997 to 24% in 2011
Fluconazole- (Diflucan-) resistant Candida (fungus)A7 –A9	Antifungal resistance in mucosal candidiasis varies by species
Extended spectrum β-lactamase–producing Enterobacteriaceae A10 ,A11	Infections have become more common in recent years
	Once confined largely to hospitals, these bacteria, especially Escherichia coli, are increasingly common in community-acquired infections, particularly urinary tract infections
Vancomycin-resistant EnterococcusA12 –A14	Enterococci are the fifth most common cause of health care–associated infections
	Most likely to be found in urine and in wounds; may pose a risk for spreading in the outpatient setting
Multidrug-resistant Pseudomonas aeruginosaA15 ,A16	About 8% of all health care–associated infections are caused by P. aeruginosa; about 13% of severe P. aeruginosa health care–associated infections are multidrug resistant
	P. aeruginosa may be isolated from outpatients with otitis, skin rash, and urinary tract infections
Drug-resistant non-typhoidal SalmonellaA17 ,A18	Estimated 1.2 million cases occur each year in the United States; most go unreported
	About 100,000 cases (8%) are caused by drug-resistant Salmonella
	Outbreaks occur each year; some involve multiple states and/or national distribution
Drug-resistant Salmonella serotype Typhi A19	Estimated 5,700 cases annually in the United States
	Most (up to 75%) are acquired during international travel
	Increasing resistance to antibiotics, especially fluoroquinolones
Drug-resistant ShigellaA20	High-risk groups include children in day care centers (younger than five years) and their caregivers, men who have sex with men, international travelers, and persons in custodial institutions
	Increasing resistance to ciprofloxacin and azithromycin (Zithromax) is of particular concern
Methicillin-resistant Staphylococcus aureusA21 –A23	Although overall cases of invasive methicillin-resistant S. aureus are declining, the proportion of community-associated infections has increased
	Should be considered in the differential diagnosis of skin and soft tissue infections
Serious
Drug-resistant Streptococcus pneumoniaeA24	Increasing threat of antibiotic resistance makes vaccination according to the Advisory
	Committee on Immunization Practices recommendations for children and adults more important
Drug-resistant tuberculosis A25 ,A26	Number of tuberculosis cases is declining in the United States 63% of tuberculosis cases in the United States occur among foreign-born persons
	Proportion of primary multidrug-resistant tuberculosis cases occurring among foreign-born persons has been increasing
Concerning
Vancomycin-resistant S. aureusA27	Rare; 13 cases have been identified in the United States since 2002
	Severity of the consequences of S. aureus resistance to vancomycin require continued vigilance for this pathogen
Erythromycin-resistant group A StreptococcusA28	Penicillin remains the drug of choice, but the resistance to other drugs needed for patients allergic to penicillin is worrisome
	Of samples tested by the Centers for Disease Control and Prevention, 10% were erythromycin resistant and 3.4% were clindamycin resistant
Clindamycin-resistant group B StreptococcusA29	Neonates, pregnant women, and persons older than 65 years with underlying conditions are at highest risk
	Penicillin remains the drug of choice, but the resistance to other drugs needed for patients allergic to penicillin is worrisome