Staphylococcal Infection

Bacteriology

Gm +ve cocci Cluster Facultative Nonfastidious

Classification

Staph. Aureus; Coagulase positive Staph. Epidermidis; Coagulase negative

Staph. Aureus Infections Mechanism of pathogenesis; 1-coenzymes local destruction 2-Secretion of Toxins 3-Superantigens activating T cell receptors 4-Interfer with opsonophagocytosis

Epidemiology Normal human flora; nose& moist areas Transmission; Hands/nose sec/contact/rarely air. Colonize; skin, newborn nasoph& umb. Invasion; Skin breaks, I/V access, immune defect, steroids and neutropenea.

Clinical conditions

Suppurative. Toxic related;

Clinical conditions Suppurative. Toxic related; Scalded Skin Syndrome SSS Toxic Shock Syndrome ??Kawasaki’ Disease Food poisoning

Skin Foliculitis Furaculosis (Boils)/Carbunkles Emptigo contagoesa Bullous Emptigo SSS (Ritter disease)

Respiratory Infections Sinusitis Parotitis Cervical adenitis Tracheitis compared to croup Pnumonia;

Sepsis Start as focal lesion e.g. a boil Yield to septicemia Localize to organs e.g. lung, bone, heart, brain etc

Muscles/Bone/Joints Tropical pyomyositis; Localized abscesses and high CPK Osteomylitis; Trauma/Sx, pain, fever Septic arthritis; Usually hematogenous

CNS Meningitis; Bacteremea, O.M, skull osteo., neural canal defects. Neurosurgical procedures and VP shunt

Heart Bacterial endocarditis; -Perforated heart valve -myocardial abscess -purulent pericarditis -Sudden death

Kidney Perinephric abscess UTI; Staph. saprophyticus (CONS) Sexually active adolescent girls

G.I. Food poisoning; Meat, mayonnase, creamed foods Short incubation period of 1 to 7 HRs Perfuse vomiting, no fever Test susp. food for staph bacteria/ toxins

Diagnosis Isolate staph. bacteria Gram stain Identify Toxins

Treatment Penicillinase resistant antibiotics; Oxacillin (Cloxacillin, Flucloxacillin) methicillin Nafcillin 1 st generation cephalosporine, cefazolin (Ultracef)

Treatment cont. Betalacamase hyperprodcer staph.; Amoxicillin/Clavulenic acid(Augumentin) Ampicillin/Salbactam Imipenem Fluoroquinilones 1 st generation cephalosporin Vancomycin

Coagulase negative Staph. (CONS) Common Skin Flora Ubiquitous organism Has affinity to plastic (surface hydophobicity & production of slim) Neonates, I/V access and shunt devices infections (nosocomial infections)

Clinical Conditions Premature neonatal sepsis/NEC. Older children sepsis is rare (minimal signs of sepsis) Persistent pactreamia usual with indwelling devices (I/V cath, VP shunt, cardiac grafts and prosthesis etc.)

Clinical Cond. Cont. Single positive blood culture is a contaminant UTI in adolescent girls Staphylococcus Saprophyticus (CONS)

Treatment Remove the access devices/shunts. May externalize the VP shunt. Vancomycin or Rifampin. Amoxicillin or Quinolones for the Staph Saprophyticus UTI.

Nosocomial Infections

Definition Infections not present or incubating at the time of admission that develop during admission or less than one incubation period after discharge

Definition cont. Infections 48 HRs or more after admission is assumed to be nosocomial unless the infection is clearly community acquired

Clean Surgery

Incision through prepared normal skin and the operative field dose not include infected tissue, abscess, or entry into normally unsterile areas such as the bowel, the upper respiratory tract, or the lower female genital tract.

Rate of Nosocomial Infections Number of nosocomial infections divided by the number of patients at risk multiplied by 100

Epidemiology 1/3 hospital infections are nosocomial (estimate in the USA) i.e. 2 million patients i.e. 4 million patient days of hospitalization i.e. 4.5 Billion USD i.e. 17 Billion SAR

Epidemiology cont. In USA (1978) nosocomial inf. rate; -All services 3.37% -Pediatric services 1.2%

Epidemiology cont. Common sites of ped. nosocomial infections (as per the NNIS);  Blood stream  Surgical sites  Lower respiratory tract  Urinary tract

Epidemiology cont. In adults;  Urinary tract  Surgical sites  Lower respiratory tract  Blood stream

Epidemiology cont. Common PEDIATRIC nosocomial bacteria;  Staphylococcus aureus  Escherichia coli  CONS  Klebsiella

Epidemiology cont. Common NEONATAL nosocomial bacteria;  CONS  Staphylococcus aureus  Escherichia coli  Group B sterptococci  Klebsiella

Epidemiology cont. Areas of high nosocomial infection rates;  NICU  PICU  Burn Units

Risk Factors of Nosocomial Inf. General risk factors;  Prior colonization with nosocomially acquired bacteria  Catheters  Exposure to antibiotics Specific risk factors  Inhalation equipments  Specific monitoring cath’s e.g. arterial cath etc.  Viral infections

General risk factors Prior colonization;  Klebsiella colonization after admission gave 50% incidence of infection  Inhalation therapy, N/G suction and antibiotics are behind the colonization

General risk factors Catheters;  Increase risk of septicemia with method of insertion, type of solution and duration of placement (I/V catheter)  Major risk of septicemia in neonates  Urine catheter is a risk for UTI in females, elderly and critical pt.’s  Risk increase with method of insertion, length of tube and break of the system

General risk factors Exposure to Antibiotics;  Prior use of broad spectrum antibiotics  Normal flora protect the host through blocking the surface receptor/attachment sites

Specific risk facors Special catheters  Pressure trasducers  Arterial catheters  Swan-Ganz catheters

Specific risk facors Viral infections  RSV close contact with infants at risk  Varicella ( 8-21 days incubation) and risk for nonimmune and immune suppressed. Screen hospital personnel  Rota virus

Prevention and control of nosocomial infections General measures;  A team of infection control team  Enforce surveillance of equipments, disinfection and isolation techniques

Specific risk factors Inhalation equipments  Nebulizers and humidifiers  Risk of necrotizing pneumonia  Decontamination with.25% acetic acid and ethylene oxide

Prevention and control of nosocomial infections Universal precautions;  Barrier precautions prevent exposure  Hand wash  Proper handling of sharp instruments  Resuscitation equipments  Personnel with exudative lesions  Pregnant health workers

Prevention and control of nosocomial infections Isolation techniques; Apply specific isolation to specific diseases

Prevention and control of nosocomial infections Hand wash practice;  Most effective and least expensive practice to prevent transmission of pathogens  Educate personnel of the method of hand wash (15 seconds with warm water and soap then dry and turn faucet with towel)

Prevention and control of nosocomial infections Intravenous therapy;  Hand wash  Clean site with 70% alcohol and 10% providone- iodine  Preferred locations in pediatrics are scalp, hands and foot  Minimize duration if possible  Prophylactic antibiotics are not recommended  Remove catheter if sign of inflammation